Learn Podcasting

Using Peer-to-Peer Distribution

2009-05-01T05:17:00.000-07:00

The last method of distribution you may want to consider is peer-to-peer. Peer-to-peer (P2P) distribution uses other people on the network to distribute files, instead of sending everything from a single centralized server. P2P distribution came to notoriety with the arrival of Napster, which was originally used to share music files across the Internet. Since then, it has gone mainstream, with many different types of data distributed in this fashion. Skype, the Internet telephony start-up, is actually a P2P application.

There are a number of different P2P approaches, but basically the way it works is that if you request a file and the P2P network knows that someone near you already has a copy of the file, you are directed to that person's computer to get a copy, instead of sending another copy all the way across the network. Sometimes, downloads are distributed across multiple computers, so you're downloading parts of a file from many different participants on the P2P network.

The advantage of P2P distribution is that is uses the audience's bandwidth, so you don't have to pay for the throughput. Instead, people are being directed to other people on the network, and they're using their bandwidth, not yours. However, P2P distribution really works only if your content is very popular.

How P2P works

To explore how peer-to-peer distribution works, we'll look at BitTorrent. BitTorrent is perhaps the best-known P2P system. There is a vast amount of BitTorrent traffic on the Internet, by some estimates as much as 35 percent of the traffic at any given time. It's anyone's guess what all this traffic is and whether or not it's legal. Regardless, it's a proven system that works well.

BitTorrent is a protocol that defines how files can be shared between two or more hosts. It's also the name of one of the programs that distributes files using the BitTorrent protocol. Essentially, BitTorrent works by breaking large files into many small pieces. BitTorrent downloads are not done sequentially, like regular FTP or HTTP downloads. Instead, BitTorrent clients download files in pieces, from as many different clients as possible. BitTorrent clients find out about the different locations they can download files from by checking in with a BitTorrent tracker, which keeps track of everyone who is participating in the distribution of a particular file. It may seem a bit confusing, but it's actually pretty simple. Here's an example of how it works:

You create a "torrent" for the file you want to distribute. This is a small file that contains all the information people need to know about the file to download it. The torrent is created in your BitTorrent application.
After the torrent is created, it is placed on a Web server and registered with what is known as a tracker. The tracker keeps track of everyone who is participating in the distribution of the file.
Next, you have to seed the file. This means getting the initial copy of the file into distribution. Usually this is done from the user's desktop. You click the link to the torrent on the Web site and indicate in your BitTorrent client that you're seeding for this file.
When the first audience member clicks the torrent link, the torrent file opens by their BitTorrent client. The BitTorrent client finds out from the tracker who is participating in the distribution. Because no one else is, the BitTorrent client begins downloading the file from the original seed file, which in this case is your computer.
When the next person clicks the torrent link and then checks in with the tracker, he finds that there are now two machines participating in the distribution: the original and the first audience member. Their BitTorrent client requests pieces of the file from both clients.
As more clients joint the torrent, the distribution becomes more and more distributed, allowing clients to download the file from many different clients. Files that are very popular have many people participating in the torrent, so the distribution process scales accordingly.
BitTorrent "etiquette" dictates that it's nice to leave your BitTorrent client on for a while after you've downloaded the file, so that you can help distribute the file to other people.

This is a simplified picture of how P2P distribution occurs, but essentially it's correct. For P2P distribution to be efficient, it requires lots of clients participating in the distribution. So when you're first starting out, P2P distribution offers very little benefit, because your audience most likely will be downloading at different times and won't be able to take advantage of the distributed download. When your podcast audience is in the thousands, then you can make an argument for P2P distribution.

Is P2P for you?

One thing that we've conveniently ignored up to this point is that P2P software is not built in to any podcatching software. Podcatchers can download MP3 files using HTTP, but they cannot participate in a P2P distribution scheme. So if you want to use P2P as a distribution scheme, your audience has to download and install P2P distribution software. Considering the antipathy some folks have to installing software, this may not be the easiest sell.

P2P distribution is used widely by the gaming community to distribute new releases and software fixes. It's a proven distribution technology that can potentially save you lots of money in bandwidth costs. The problem, however, is that it isn't yet integrated into podcasting in any meaningful way. Although P2P may be an effective way to scale podcasting distribution in the near future, for the time being you're probably better off sticking to other methods of distribution.

Using a Content Distribution Network

2009-04-27T06:42:00.000-07:00

Content distribution networks (CDNs) are designed to deliver large volumes of traffic quickly and efficiently. Whereas a Web host may have hundreds of servers in a single location, a CDN has multiple data centers, and generally the data is replicated across each data center. This is done both for data integrity, so that if there's a power failure somewhere your files are still available, and also for speed. Most CDNs also rely on caching to make downloads happen faster.

Caching is a technique where the most popular files are stored at multiple locations so that when they are requested, the request doesn't have to go all the way back to the origin server. For example, let's say http://CNN.com has an extremely popular story on its home page. The origin servers are most likely in Atlanta, where CNN is based. The first time someone in Los Angeles requests the CNN home page, a copy, along with all the images, is sent from Atlanta to Los Angeles. Then a copy is stored in a cache somewhere on the west coast, so that the next time someone requests that page, it can be served directly from the local cache and not re-requested from the origin server in Atlanta.

CDNs offer premium delivery services, so you won't find pricing like you can with the Web hosting services. CDNs also like to deal in very large numbers, so if you're not expecting to spend hundreds of dollars a month, you shouldn't waste your time calling CDNs. However, when your podcast is at a stage where you have a large audience that demands quality service, a CDN is your best bet.

The CDN marketplace

The CDN market is often divided into the "tier 1" providers, who have the largest and fastest networks, and the "tier 2" providers, who may have slightly more aggressive pricing but may not offer the same service. CDNs are often graded in terms of their availability, which some brag about in terms of "five nines." This means that their network is available 99.999 percent of the time. Another metric used to grade CDNs is the response time, which is the average amount of time it takes for a CDN to respond to a request. A number of services grade CDNs from time to time on their performance. The CDN market has seen lots of consolidation in the last few years, and prices have dropped considerably. The performance of the tier 2 CDNs has come so close the tier 1 providers that the tier 1 providers have had to drop their prices to remain competitive. Some even question whether there is enough distinction between providers to classify them into separate tiers anymore. Be that as it may, these are some of the better-known CDNs:

Akamai (http://www.akamai.com)
Mirror Image (http://www.mirror-image.com)
Limelight (http://www.limelightnetworks.com)
Savvis (http://www.savvis.net)

CDN pricing

CDNs use two basic models for pricing. Traditionally, they have billed using what is known as the 95th percentile model; recently many are moving to a per megabyte/gigabyte model. One of the frustrating things about CDNs is that it is almost impossible to translate between these two pricing models, making it difficult for CDN customers to figure out their cost of delivery.

Using the 95th percentile model, your price is quoted as a dollar amount per megabit of concurrent throughput. For example, a CDN may offer you a price of $50 per megabit. The tricky part is how your concurrent traffic figure is arrived at over the course of a month. The CDN measures exactly how much throughput you are using many times over the course of each day. At the end of the month, the CDN tabulates all the measurements, discards the top 5 percent of the measurements, and uses the 95th percentile measurement as your billable amount.

Note

Billing at the 95th percentile is measured in terms of megabits, not Megabytes. Be careful when you're doing your calculations!

Here's another way of looking at it. There are 720 hours in a 30-day month, so 5 percent of a month translates to 36 hours. So when you're billed at the 95th percentile, the busiest 36 hours of the month are discarded, and you're billed for the throughput your site used during the 37th busiest hour. Still confused? Don't worry, you're not alone. This model is frustrating to customers, because it is hard to understand and hard to budget for. In some ways, it's good because you don't pay for momentary spikes in your traffic. On the other hand, it's very hard to calculate your cost of delivery on a per-file basis because that varies depending on your traffic patterns.

For example, let's say you've got 1,000 subscribers, and you put up a new podcast each day. Over the course of that day, all 1,000 of them check the RSS feed and download the podcast. Assuming the same 5-minute, 5-MB file we talked about earlier in the chapter, and assuming folks are on an average broadband connection of about 300 Kbps, it's going to take the average listener about 2 minutes to download your file:

5 MB * 1024 MB/KB * 8 bits/byte = 40,960 Kbits
40,960 Kbits / 300 Kbps = roughly 136 seconds (fudging the
difference between K and k)

Given an ideal distribution, over the course of a day, just over 700 people could download your file, one at a time, and you'd never have more than one person at a time downloading. But given that most of your listeners probably will be from a limited number of time zones, and most folks will check their favorite feeds either at lunch time or early in the evening, you'll probably get the bulk of your downloads during three or four hours a day. That means you'll have around 5 to 10 people downloading at any given time. Let's say 10 for a liberal estimate. This means your concurrent throughput during these hours will be:

10 * 300 Kbps = 3 Mbps

This should end up being your 95th percentile number, because you're hitting this peak for 3 to 4 hours each day. If you're paying $50 per megabit, you can then do some math to figure out what your cost per delivery is per file:

3 Mbps * $50 = $150
1,000 subscribers * 20 podcasts/month = 20,000 podcasts
$150 / 20,000 podcasts = under a penny a podcast

So it's not impossible to get your cost of delivery, but it involves some calculation. And the calculations are highly dependent on your traffic patterns. Your bill depends on when people download the file, not how many. So it's very hard to figure out what your incremental cost per subscriber is, because it depends on when they download the file!

For this reason, some CDNs are now offering pricing on a per gigabyte basis. Using this model, customers are billed for the total amount of throughput they use. It doesn't matter when the throughput is used. This model is much simpler for customers to understand, because the math is straightforward. Using the previous example, let's calculate what the cost would be, assuming a cost of $1 a gigabyte:

20,000 podcasts * 5 MB/podcast = 100,000 MB = 100 GB
100 GB * $1 = $100
$100 / 20,000 podcasts = half a penny a podcast

Using this model, it appears that it's cheaper, and we know it's a hard cost that we can use in our calculations. Each podcast costs a half a penny to deliver. Contrast this with the 95th percentile where we know the cost is under a penny, but that could change depending on traffic patterns. However, don't let these numbers fool you. It's not quite this simple.

Let's say your podcast audience doubles in size. Using the cost-per-gig model, we know our costs would double. However, with the 95th percentile model, they may not. An audience that's twice as large quite probably would come from a much more dispersed geographical area and may distribute the load over more hours in the day. It's quite possible that you could double your audience size and not pay any more at all! That's the tricky part. If you make efficient use of your bandwidth, the 95th percentile model can be substantially cheaper.

Some companies put caps on bandwidth usage, so for example they're never using more than one megabit per second. This slows down file delivery for people if they're all trying to download at the same time, but keeps costs low. In fact, this is a tool that some hosting companies use to make sure they keep their costs low. (How else do you think they can offer so much bandwidth for free?) You may be able to do the same if you work with your CDN. This compromises performance for your listeners, but it can be a good cost-savings mechanism.

Using a Podcast Hosting Service

2009-04-24T09:39:00.000-07:00

Podcast hosting services are very similar to Web hosting services, but with product offerings geared towards podcasters. You generally get a certain amount of storage space and throughput, and depending on the service, you may get a Web site or a blog, tools to author your RSS feed, and statistics regarding your podcast.

The tools that podcast hosting services offer make them a great bet for folks who are not technically savvy. Also, many of the podcast hosting services are using an interesting model where they charge for the amount of storage you use, but don't charge for throughput. This is an interesting approach and a great deal if your podcast becomes extremely popular. However, as mentioned in the preceding chapter, using a podcast hosting service means giving up some of your ownership, because you won't be able to use your own URL for the site.

However, you could use a hybrid approach where you host your Web site at a Web host and your media file at a podcast hosting service. You'd still have access to the RSS tools, and you could either host the RSS feed from your Web site or point to the RSS feed on the podcast hosting service. It's a little awkward in that you're using two separate services instead of one, but you may be able to get the best of both worlds this way.

Tip

Another benefit to some hosting services is that they may offer the possibility of advertising or sponsorship to help pay for your podcast. For example, Liberated Syndication is partnered with Kiptronic to offer ad placement and sponsorship opportunities. Granted, you don't have to be a LibSyn user to take advantage of Kiptronic's offering, but if you are, the integration is seamless and taken care of for you.

Distributing Your Own Podcast Using Box Populi
Box Populi offers an interesting solution for folks who plan on creating a large number of podcasts. It's a two-part solution that takes care of the production and encoding of podcasts as well as the distribution.

To start off with, they have a product called Podcast In A Box that you use to create your podcasts. Plug a microphone into the 1/8″ mic input, and then plug in the USB key that comes with the system. Recording begins automatically. When you're done, remove the USB key, and your podcast is automatically encoded into MP3 format and uploaded to a Web server.

Box Populi's Podcast In A Box automates podcast production, encoding, and distribution.

Box Populi can host your podcast for you, or if you prefer they sell a rack-mountable media server that is tightly integrated with Podcast In A Box. The server auto-publishes your podcasts to a Web page and enables management through a simple browser-based interface. You can host audio or video files using the media server, and you can create multiple user accounts so many folks can contribute to your podcast. If you decide to start using a CDN, the media server can be configured to automatically upload your podcast media files to your CDN.

The entire system is built on open-source software, and Box Populi will do custom development for you if their tools don't already do exactly what you want them to do. If you're looking for an end-toend podcasting solution, check out Box Populi.

Using Your Web Server

2009-04-20T05:37:00.000-07:00

The simplest case is to host your podcast media files right on your Web server. When you're starting out, this is probably the way to go. Most Web hosting agreements usually include a fair amount of bandwidth these days, which cover a fair amount of downloads. For example, here are a few of the better-known Web hosting companies and the deals they're currently offering:

IX Web Hosting (http://www.ixwebhosting.com): $3.95 a month, 100 GB storage, 1,000 GB throughput
Host Excellence (http://www.hostexcellence.com): $2.95 a month, 5 GB storage, 50 GB throughput
iPower Web (http://www.iPowerweb.com): $7.95 a month, 50 GB storage, 750 GB throughput
Dreamhost (http://www.dreamhost.com): $7.95 a month, 200GB storage, 2TB throughput
1 and 1 (http://1and1.com): $2.99 a month, 5 GB storage, 250 GB throughput

As you can see, killer deals for cheap Web hosting abound. However, as the saying goes, there's no such thing as a free lunch. The only way they can offer these kinds of prices is by putting hundreds if not thousands of Web sites on each server. You'll be sharing resources with lots of other folks. In some cases, this may not be a problem. However, sometimes it can be problematic. Your listeners may have to wait longer for your pages and your podcast files to download.

When you're first starting off, prices like these with the amount of storage and throughput they're giving away are pretty hard to pass up. Many of these services also offer fairly comprehensive tool sets that allow you to build Web sites and create e-commerce pages, blogs, and forums, and they'll even host your e-mail.

If you're thinking of going this way, it's really important to comb the comparison sites and the forums of your potential partners. See what people are saying about them and whether their existing customers are happy. Don't just go by the testimonials they put on their home page; dig into their message boards if you can, and search them to death. It's not that the couple of dollars a month is going to break your budget; it's more that after you're settled into a Web host, changing can be a painful experience.

Tip

A number of sites out there regularly update the ratings for Web hosting services. Just search for "best web hosting" and you'll have a number to choose from.

Distributing Your Media File

2009-04-17T09:30:00.000-07:00

Although the discussion was couched in somewhat general terms and assumed that your podcast and the Web site hosting your podcast were the same thing, they don't have to be. You can host your Web site using one solution and host your podcast media files somewhere completely different.

You may want to do this for several reasons, but they all generally boil down to the fact that MP3 files are much larger than Web pages, so you're going to use lots of bandwidth and lots of storage. This places unique demands on the server infrastructure, which may be a job handled by a trusted partner.

Understanding Distribution

One of the best things about podcasting is that it doesn't require any special serving software, like streaming media does. You just place the file on your Web server and update your RSS feed, and you're done. That's all fine and good when you're starting out and have a handful of faithful subscribers. But what happens when your podcast becomes wildly popular?

Several things happen. First, instead of downloading a handful of MP3 files to your listeners, you're suddenly sending out thousands of copies of your MP3 file. If your podcast is 5 minutes long and encoded at 128 Kbps, you're looking at a 5 MB file. A thousand downloads means you're talking about 5 GB of throughput. If you have a daily show, you're talking about over 150 GB per month. That's a pretty serious amount of traffic.

At this scale, things change significantly. Instead of sending out a few files when your friends check to see if you've updated your blog, your Web server is now running all day long. That means the disc drives are spinning, and much more wear and tear is being put on the machines. Servers have a much shorter shelf life than desktop computers for this reason. Most hosting companies plan on servers lasting approximately three years before they have to be replaced.

Of course, this is assuming that your podcast becomes popular enough to attract a large audience. That may not be your case. Your podcast may be niche content that is devoutly followed by a faithful few. Disregarding the size of your audience for the time being, your choices for hosting your media files break down as follows:

Host it on your Web server.
Host it on a content distribution network (CDN).
Host it on a podcast hosting service.
Use peer-to-peer distribution.

In the following sections, we talk about each of these possibilities in a little more detail.

Using Feed Icons to Publicize Your Feed

2009-04-14T11:24:00.000-07:00

Chances are good that you'll get most of your subscribers from the larger directory services if you're diligent about listing your podcast. However, that's not the only way to get subscribers. Quite a few may find your Web page via a search engine, particularly if your topic is unique. In this case, it's important to showcase your podcast on your Web page. You want visitors to know in a split second that your Web page is more than just a blog. You want them to see that you have a podcast and that they can subscribe with a single, easy-to-find button.

Until recently, the problem was that there was no single universally accepted icon to indicate that a podcast was available. Different sites used different icons and different colors. Some folks took the original RSS icon, which was a small orange box with the letters "RSS" in white, and substituted the letters "POD." The good people at the Mozilla Foundation decided it would be best if a standardized icon were developed. The logic behind the development was that the icon should not include any abbreviations or acronyms, because people wouldn't necessarily understand what XML or RSS stood for, nor should they have to. They came up with the orange icon shown in Figure 1 (shown here in grayscale, obviously).

Figure 1: The "standardized" RSS icon

As with most things in the world of podcasting, the icon was loved by some and hated by others. There was plenty of lively discussion, which was pretty much brought to a halt when Microsoft decided to use the same icon for its upcoming Internet Explorer 7.0 release. Although you'll probably still see mavericks out there using their own iconography, most people will gravitate toward the Firefox/IE icon, and it will become the de facto standard.

Note

The Mozilla Foundation has publicized usage guidelines for feed icons here:

www.mozilla.org/foundation/feed-icon-guidelines/

In most cases, you'll want the RSS icon to link to your RSS feed. However, for those folks who subscribe to podcasts using iTunes, you can make their subscription easier by posting a link to your feed via the iTunes store. For example, the link to subscribe to the Dawn and Drew Show on iTunes looks like this:

phobos.apple.com/WebObjects/MZStore.woa/wa/viewPodcast?id=73331700

When you click this link, it automatically opens iTunes and subscribes you to the Dawn and Drew show, with just one click. To find out what the direct link to your podcast in iTunes is, just Ctrl+click (right-click in Windows) the image you uploaded for your show. This opens a little window that lets you copy the URL for your show for linking purposes.

Now that you have the iTunes direct link, the question is what icon should you use to link to it? You don't want to use the standard RSS icon, because it doesn't work for folks who don't use iTunes to listen to podcasts. You want some way of letting people know that the link is specifically for iTunes users. Unfortunately, there's no right answer here. Folks have designed their own icons for this purpose, and there is no Apple-approved version.

Of course, if you're offering a special button for iTunes listeners, you may also want to offer a button for folks who use Yahoo! Podcasts, Odeo, Google, or any other number of podcast subscription services. And if you're offering your podcast in a number of different formats, you need to have an RSS feed for each format and ideally some sort of icon for each one. Again, there are no standards here. Peter Forret has created a nice set of icons that use a miniaturized version of the RSS feed icon along with wording indicating what the buttons specifically do. You can see his icons here:

web.forret.com/tools/podicons.asp

Note

If you want to tweak what Peter has done, he's kind and modest enough to admit that he used a cool online tool to create his buttons, and you can too — the Brilliant Button Maker:

www.lucazappa.com/brilliantMaker/buttonImage.php

Dedicated Podcast Hosting Services

2009-04-04T09:13:00.000-07:00

Dedicated podcast services host your podcast files, provide statistics, and automatically generate your RSS. Some also include a Web site, which is usually a blog. Quite a few of these services are available at various price points and offering different services. For example, most offer some sort of Web site with your account. Some offer a free service, but place ads before your podcast. Many offer a trial period, which is a great way to see how well their tools work. Following are a few examples of podcast hosting services.

PodOMatic

PodOMatic(http://www.podomatic.com), shown in Figure 1, is a complete podcast hosting solution, complete with a Web site for each member. PodOMatic offers both free and paid accounts. The free service gives you up to 15 GB of data transfer and 500 MB of storage per month. They also have two levels of paid service called Pro and Pro+. The Pro service upgrades your storage to 2 GB and upgrades the bandwidth to 100 GB per month, which they say is equivalent to 4,000 downloads per month for a 15-minute show. The Pro+ service upgrades the transfer to 200 GB per month or 8,000 downloads. PodOMatic Pro is $9.99 per month; PodOMatic Pro+ is $14.99 per month. The Pro services also offer enhanced statistics including what they call geo-ip maps showing where your listeners are on a map of the world.

Figure 1: PodOMatic is a dedicated podcast hosting solution.

Liberated Syndication (Libsyn)

Liberated Syndication, or as it's commonly called, Libsyn (http://www.libsyn.com), is another complete podcast hosting service, offering service at rates based on the amount of storage you use, with no limit on the number of downloads. Libsyn, shown in Figure 2, charges by the month for its services, which come in $5, $10, $20, and $30 levels with 100MB, 250MB, 525MB, and 800MB storage capacities respectively.

Figure 2: LibSyn charges only for storage, not for bandwidth used.

One of the nice things about Libsyn is that it gives you advanced statistics, shown in Figure 3 even with the lowest cost service.

Figure 3: LibSyn offers detailed statistics to all members.

Radio Userland

Userland (http://radio.userland.com), shown in Figure 4, was founded by Dave Winer, the inventor of RSS and co-inventor, along with Adam Curry, of podcasting. Radio Userland is the oldest blogging service and has had podcasting support built in since the very beginning. Radio Userland has both a Web and a desktop-based component to its service. A basic subscription is $40 per year. Radio Userland does not provide hosting support for your podcast files, but it does have one of the all-time best set of blogging features.

Figure 4: Radio Userland is the granddaddy of all podcast hosting services.

Blogging services with podcasting support

Many blogging services are starting to offer podcasting support. Some have integrated podcasting support, some have add-ins you can use to enable podcasting support, and some require the use of services such as Feedburner or can be used with a manually created RSS feed.

Here is a short list of some blogging services with different degrees of podcast support:

WordPress + PodPress: Wordpress (http://www.wordpress.com) is a popular blogging service, and PodPress (http://www.mightyseek.com/podpress/) offers a Wordpress plug-in that supports podcasting.
Moveable Type: Moveable Type (http://www.sixapart.com/movabletype/) is a free blogging service that can be used with Feedburner.
MSN Spaces: MSN Spaces(http://spaces.live.com)is the largest free blogging service and can support podcasting by using Feedburner's SmartCast feature.
TypePad: TypePad (http://www.typepad.com) offers built-in podcasting support.

Retaining Ownership

2009-03-24T09:13:00.000-07:00

Ownership is another thing to bear in mind when you're making the decision about where to host your podcast and what software you're going to use. Another way to think about this is using the concept of brand. If you're spending lots of time and effort to create a successful podcast, your podcast, Web site, URL, and everything to do with your production are part of your brand. Building a successful podcast goes hand in hand with building a successful brand.

Successful companies have what's known as brand equity. That's why soft drink companies are extremely protective of their brands. They know their brands have intrinsic value, and they don't want anyone else to be profiting from them. You should be thinking the same way as you build your podcasting empire. If your podcast becomes wildly successful, you want the rewards from that success to come back to you — not your podcast hosting partner or your Web hosting partner. These people may play an important part in your success, but without your success, they're just hosting companies. You're the one bringing the programming to the table.

For this reason, it's important that you seriously consider retaining ownership of everything related to your podcast. Earlier in this chapter, we mentioned that you should register a URL for your podcast, and this is a prime reason why. If you're hosting your site on someone else's service, you're surrendering some of your brand equity. As your brand builds, you're also building someone else's brand, because everyone coming to your site sees your hosting partner's branding. This isn't necessarily a bad thing; you may, in fact, be building your brand on the strength of an existing podcast directory's brand. In the long term, however, you want to be able to focus on building your own brand, not someone else's.

Similar to registering your own URL, you should also retain ownership of your RSS feed. It's great that many podcast hosting solutions offer tools that automatically generate valid RSS feeds. However, these feeds live on their servers, so the URL to your feed ends up being:

www.podcastpoodle.com/feeds/mypikepodcast.xml

Part of that URL has your branding, but the other part has your podcasting host's branding. The problem here is deeper than just the URL. After all, the URL may be hidden beneath a large "Subscribe to my podcast!" button that you put on your home page, so folks may not even notice the branding attribution. The problem is what do you do when you decide to part ways with Podcast Poodle? Everyone who has subscribed to your podcast has done so via the hosting service URL. You have to wean your audience off the old URL of your RSS feed to the new URL, which may not be a simple task, particularly if you have thousands of listeners.

A better approach is to keep control of your RSS feed, so that all your subscribers are coming in through your Web site, subscribing via your RSS feed. That way, you can change hosts at will, Web or podcast, and your audience won't notice a thing. If you change Web hosting partners, people will still find your Web site through the magic of the Internet's Domain Name System (DNS). They just type http://mypikepodcast.com, and presto, your site pops up. Similarly, if you change hosts for your media files, you just have to change the contents of your enclosure tags in your RSS feed, and no one will ever notice.

Granted, managing your own Web site and maintaining your own RSS feeds may not be for everyone. It requires a significant amount of responsibility and technical know-how. There's a reason that podcast hosting companies are popular: The convenience is hard to pass up. If you decide to go the hosted route, just remember that you may be faced with a difficult decision later if your podcast is as successful as you hope it will be.

Finding a Home for Your Podcast

2009-03-12T09:09:00.000-07:00

Now that you have an understanding of what RSS is and how to create an RSS file, it's time to figure out how the RSS feed fits into your Web site, where to put it so that people can find it, and how to keep it current. It's not that difficult, but there are a number of different ways to do it, so you should do some long-term thinking about how you want to manage your podcast and your Web site.

You have to make a number of decisions revolving around the two main aspects of your podcast, your Web site and your media. The decisions you make now have a direct effect on your production chain and also affect your long-term planning. After you launch your podcast and crank up your Web site, it can be difficult to change your approach mid-stream.

Let's start with an overview of the different ways that you can bring your Web site and podcast to market, along with some of the basic benefits and drawbacks of each option.

What Are the Options?

Up to now, all we've really discussed is how to create your podcast media file, and we talked a little bit about authoring your RSS feed. There's another aspect that can be just as critical to your success: your Web site. Podcasting began as a way to add audio to blogs, and to have this audio automatically transferred to an iPod. However, the concept of podcasting has grown since then. Informal studies have shown that up to 50 percent of all podcasts are watched while sitting in front of a computer. Many of these may be played on iTunes running in the background, but a significant number are also watched on Web sites as embedded presentations.

Podcasting purists are quick to say that these aren't really podcasts. (Some, in fact, say that anything other than an MP3 file is not a podcast.) Call it what you want: A ton of programming is being produced and distributed on the Internet using RSS feeds. This programming can be experienced in many different ways. The question is what sort of experience do you want your audience to have?

In an effort to try to impose some sort of order on this chaos, we can divide the different options into three main categories of ways to host your podcast:

On a Web site or blog that you manage and maintain yourself
On a managed Web site or blogging service
On a dedicated podcast hosting service

Each of these has advantages and disadvantages. In a nutshell, if you're willing to take on the burden of managing and maintaining your site, you'll have the most flexibility and freedom. This flexibility comes at a price, though. If you're managing your own site, you have to worry about lots of things, such as software updates, hackers, spammers, and hardware problems. If you use managed or dedicated systems, you have much less to worry about, but this ease of use comes at the price of flexibility. You may not be able to install some new gadget on your site that you found on an opensource forum, or you may not be able to embed the latest video technology due to support issues. Let's talk about the options in a little more detail.

Managing your own Web site

Managing your own Web site can be lots of fun, but it can also be lots of work. First, you have to either build a server or buy space on a shared server from a Web hosting provider. Some Web hosting providers allow full access to the operating system so that you can tinker to your heart's desire, while others place fairly serious restrictions on what you can and cannot do.

The nice thing about managing your own site is the complete freedom to do what you want, when you want. Assuming that you're running on your own server and have full access to the operating system, you can add forums, install a wiki (a shared space where people can add and edit content at will), change the look of your home page, or do anything else that strikes your fancy. You don't have to wait until a host adds new features; you just add them yourself.

Of course, this assumes that you're very comfortable running a server and installing software. Many blog and content management system (CMS) software packages install fairly painlessly these days. At the end of the day, however, if something breaks, you have no one to call. Everything is just fine until something breaks, at which point running your own server can become a nightmare, particularly if your podcast becomes popular and your audience is baying for more.

Scalability is another issue. If your podcast becomes wildly popular or if for some reason iTunes decides to put you on the podcast directory home page, the traffic to your Web site will spike. Web servers are not that complicated, but they can break down, and if they do, it's almost invariably due to a large increase in traffic — precisely the most inconvenient time for them to do so.

As the saying goes in the world of start-ups, having capacity issues is "a good problem to have." If your podcast is so popular that you're frying the small server at the end of your home DSL line, chances are good that you'll be able to afford a new server or afford to move to a managed hosting service. You should try to run your own server only if you're a seasoned Internet veteran with access to some reasonable server hardware and some free time. If you're just starting out, you should consider a managed hosting service or a dedicated podcasting hosting service.

Using a managed hosting service

The next step up in the hosting world is to use a managed hosting service. There are literally hundreds of different hosting options out there. When you register the URL for your podcast, chances are good that the company you use to register your URL will offer some sort of hosting package for your site. Hosting packages generally offer a certain amount of free storage and throughput each month, and you pay overage charges when you exceed either of these.

Some hosting packages come with pre-packaged software that allows you to create a Web site from pre-existing templates or a content management system that allows you to easily manage your Web site. If you're thinking about including e-commerce on your site, you'll need e-commerce capabilities. Many hosting service providers offer "shopping cart" functionality and may even be able to process credit card transactions for you.

One thing you'll want to make sure the service offers is statistics about your Web site traffic. If you're serious about turning your podcast into a business, you'll need accurate traffic statistics to gauge the success of your programming and to lure potential sponsors and advertisers. You should look for as much statistical information as you can find. A number of standardized Web stats packages are satisfactory, but the best hosting companies will offer incredibly detailed stats.

Perhaps the greatest thing about using a managed hosting service is that a significant amount of responsibility is taken off your plate. You no longer have to worry about hardware, and spammers and hackers are the hosting partner's problem. Also, if your statistics are showing a strong upward trend, you should be able to predict when you're going to run out of capacity and work with the hosting partner to add more capacity.

The only drawback to using a managed hosting service is that you may be limited in the software you can install. It depends on the type of service you purchase. You can purchase a shared server, in which case you're usually fairly limited, because the server must be a reliable hosting environment not just for you, but the other clients on the same server. There may be hundreds of other Web sites running off the same shared server.

Hosting services generally also offer dedicated servers, where you essentially lease hardware from them and they keep it up and running. Different hosting services allow different levels of access. Some let you do anything you want to do, while others limit what you can do so that the machine conforms to their standard, which makes it easier for them to maintain. The service you choose depends largely on how much freedom you want to install and modify software.

Using a dedicated podcast hosting service

Dedicated podcast hosting services are managed hosting services that are highly customized for a podcaster's needs. For example, these services usually offer tools to create and update your RSS feed. They may even be automated through some sort of wizard so that when you upload a new media file, your RSS feed is automatically updated. Many dedicated podcast hosting services also offer some sort of Web site for their clients, typically in the form of a blog. The blogs often come with their own URL, so that you can have a somewhat custom Web address. For example, let's pretend that you've decided to host your podcast about pike fishing with a company called Podcast Poodle. You'd probably be given the option to register your own URL like this:

mypikepodcast.podcastpoodle.com

As good as this may seem, it's not as good as having your own URL, such as:

www.mypikepodcast.com

In the first example, your Web site is what's known as a subdomain of the master domain, which in this case is http://podcastpoodle.com (please don't register this and sue us). Essentially, you're piggybacking on the master domain. This isn't much of an issue if you're a tiny podcaster, but if you make it big, you really want everyone coming to your Web site, not a page on someone else's site. When you use one of these services to host your site, you are giving up a degree of control, which you may not be happy about later.

That being said, it's hard to argue with the convenience these services offer. They make it extremely easy to get a simple Web site up and running, to keep your RSS feed updated, and to monitor how popular your site and podcast are, because they usually run top ten lists and feature different podcasts from time to time. Many also offer automated tools to list your podcast in a number of other directories, which is especially important when you're first starting out.

Some podcasting hosting services have become destinations themselves, either because they host other popular podcasts or have been around long enough that folks know it's a good place to find podcasts. This can be another compelling reason to go with a dedicated podcast hosting service. They already have an audience looking for podcasts, and there's a good chance that they'll check out your podcast if you're the new kid on the block.

You probably won't have lots of freedom to modify your Web site on these services, because they're so highly specialized to begin with. You also may not own all the real estate on your Web page. For example, the hosting service may reserve the right to advertise on your Web page in order to recoup some of their costs. They may also want to put an ad in your podcast. Seeing as how many of these podcast hosting services give away a serious amount of bandwidth and storage, it's not surprising that they want to try to earn a bit of money from your podcast. It comes with the territory.

Caution

Be very careful when signing up for a podcasting hosting service. Some incredibly bad contracts have been floating around that would make any respectable lawyer blush. One host in particular had language in its contract that specified that any podcast placed on its service immediately became the property of the host. In another case, a host was found to be modifying all the RSS feeds hosted on its service, crediting the podcasts to, you guessed it, the hosting service. It may seem like common-sense advice, but read everything put in front of you, preferably with a lawyer present.

What solution is best for you?

With all these options available, how do you choose what is going to work best for you? We can try to summarize your options here:

Managing and hosting your own Web site is really only an option if you're very savvy or if you already have an existing site to which you're adding a podcast. You may run into scaling issues, but because you're savvy, you'll be able to solve them, right?
Using a managed Web hosting solution is a great option for your Web site if you're experienced. The more Web savvy you are, the more you can get out of a managed solution. You'll have your own URL and the freedom to do what you like to your site.
Using a dedicated podcast hosting service is a great idea if you're just starting out and don't know much about Web sites. You can't beat the convenience, and they allow you to focus on the programming, which is what you should be doing anyway. If you outgrow the service, you can cross that bridge when you come to it.

One thing to mention is that this doesn't have to be an either/or situation. For example, you could host your Web site with a managed hosting solution and then use the dedicated podcast hosting service just to host the podcast file! Just because a podcast hosting solution offers you a simple Web site doesn't mean that you have to use it. In fact, this is probably the best option for the savvier user. Use a podcasting hosting service to host your podcast media files, and you'll be able to take advantage of its RSS tools, its statistics, and any other special tools it may offer. Then, host your site, complete with your personalized URL, with a Web hosting service, so you can have more flexibility with your site.

Filling a Niche by Focusing on a Specific Area of Interest

2009-03-03T14:55:00.000-08:00

Deciding what topics you can talk about is an important step, but it’s time for the application of what we like to call Jurassic Park logic. JP logic requires you to ask yourself this question: You’ve spent a lot of time thinking about whether you could, but have you figured out whether you should?

While we’re not trying to put you into tidy boxes or for an instant suggest that adding your voice to a busy conversation is a waste of time, we are suggesting that you strive to introduce a new topic to the podosphere, or find an underserved audience. Yes, you could create yet another music podcast featuring an eclectic mix of podsafe music artists. But realize that you will be competing with the dozens — perhaps hundreds — of shows out there doing basically the same thing.

You’ll best serve the current and future audience of podcast listeners by selecting a niche topic. This stands in stark contrast to traditional broadcast media, where the idea is to select broad-reaching topics to maximize the coverage area. That’s fine in a world where only so many stations fit on a radio dial, but that’s not where we live. Go for the small and focused. It’s where you’ll find the most loyal audience just waiting for you to start talking.

Determining whether you’ll have enough to talk about

One of the perils of going niche is making sure you have enough material with which you can create new episodes. A show centered around the intricacies of reattaching lost buttons to ladies’ blouses might limit your options in the future. However, that might make an excellent episode of a podcast about tailoring or seamstressing (is that a word?).

Our advice is to write down the topics and subtopics that come to mind. Don’t worry — you’re not planning out your show production schedule for the next six months. If you can list ten items of interest with only a few minutes of thought, you’ll probably be fine.

Helpful Hint

You never know when show topics will hit you, so figure out a system for jotting down the inspirations when they strike. One of your authors uses a portable Moleskine notebook (overpriced notebook, claims the second); the other keeps an outliner application at the ready (though the first wonders why inspiration only strikes at the keyboard). Figure out what system works best for you. Heck, sticky notes are a great way to start. Anything that allows you to collect ideas as they come is good to have.

Considering whether anyone will listen

Once you know you have enough to get started on your first five to ten episodes, you’ll want to do a final sanity check: Is there anybody out there waiting to listen? We hesitated before putting this section out there and remain torn as of this writing. But in the end, practicality won out. You can have exceptional diction, excellent production values, and extraordinary content — but someone other than you and your mom needs to care.

Luckily, this shouldn’t be a problem for you; more (sometimes way more) than one person always seems to be interested in the most obscure things out there. Keep in mind, however, that audience size and podcast topic are intimately related. If a large audience is your goal (and we’re not saying it should be), then select a topic that appeals to many.

Taking Inventory of Your Interests

2009-03-01T08:51:00.000-08:00

Let’s start this off with the most important person in the equation: you. No, it’s not your audience. It’s not the community you aim to serve. It’s not even the person who might have paid you to pick up the mic and start cranking out episodes. We’ll even tell you that it isn’t your spouse, though as we say this we cast a wary eye over our shoulders, burning through even more SPUs (which we explain later).

The host of the show is the lifeblood of the show. We’re not trying to put undue pressure on you, but your show won’t get very far if the topic isn’t something that you (a) want to talk about and (b) can talk about while (c) demonstrating that you know what you’re talking about. So what can you talk about? What do you want to talk about?

To be fair, you may have had the idea of doing a podcast thrust upon you as part of your job. That’s fine. Unless your boss has arranged for someone to hand you a completed script to read in front of the microphone (in which case, you probably aren’t reading this anyhow), you’ll still benefit from the suggestions in this section.

List what aspects of your job interest you

Like it or not, we spend a lot of time at our jobs, developing skills and competencies we use in our personal lives as well. While there is no question that some of your daily tasks at a job might fall into the mind-numbing category, examine those parts of your job that you do find interesting.

Notice we didn’t say day job. The reality is that for many people with the drive and ambition to even consider becoming podcasters, the wearing of two hats is commonplace. It’s not uncommon to take off the Accountant hat at 5:30 and assume the mantle of Community Organizer, Sports Memorabilia Collector, or Classic Car Restorer. These are every bit as much of a profession as that which provides the majority of your household income. The pay just stinks.

We recommend making a list of the things you do in your profession that most interest you, keeping the following points in mind:

You can get very specific or very broad — you can always refine or group tasks together later.
Be sure to include the aspects of professional affiliations, groups, or associations to which you may belong. Within all of these are hidden gems that may very well lead you to the right topic.

Jot down what you like to do for fun

What else turns your crank that you enjoy doing in your leisure time? All work and no play makes Jack a very boring podcaster whom no one much wants to listen to or talk with. And let’s face it, the possibilities for entertainment-focused podcasts are endless.

Look — you don’t have to be in this for the money. Some of the best-produced and most rewarding shows are created by people for the sheer fun of it. Perhaps you are an avid bowler and would like to share your passion with others. Maybe you know a ridiculous amount about beer. Perhaps your friends all turn to you for information when it comes to obscure knots and stitches, and everyone knows it takes you half as long to knit a sweater than anyone else on the block.

The idea is to find out what you are passionate about. Jot down a few ideas and see if you can come up with five or six subtopics worthy of further discussion. And remember that you don’t have to be the most knowledgeable person on the planet on a given topic. If you have the passion, it might be fun to take your listeners on the journey as you learn more

RSS: Podcasting's Secret Sauce

2009-02-28T20:39:00.000-08:00

The RSS file really is the secret behind podcasting. RSS is an acronym for Really Simple Syndication.

In the late 1990s, during the first Internet "boom," companies such as Marimba, PointCast, and DataChannel offered news distribution based on a technology known as "push." Push technology delivered information to client PCs when the server was ready to push the content. This turned out to be technologically impractical because the server tried to push the information out all at once, which consumed huge amounts of bandwidth and clogged personal and corporate networks.

A new model called "poll then pull" evolved. In this model, the server did not send out updated information until it was asked for by individual clients. RSS, inspired by the various content syndication formats used in push technology, was originally proposed by Dave Winer in 1997 while he was running a company called Userland. RSS was designed to enable a particular form of news syndication known today as blogging. Other companies such as Netscape and Microsoft developed versions of their own known as RDF and CDF.

Winer attempted to work with Netscape and Microsoft until Netscape abandoned the effort in 1999, and in late 2000 Userland released version 0.92 of the standard. Optional elements including the crucial tag were added in 2002, and RSS was eventually standardized in its current form in July 2003. Several versions of the RSS story exist; you can read them at these sites:

http://blogs.law.harvard.edu/tech/rssVersionHistory
http://goatee.net/2003/rss-history.html
http://www.rss-specifications.com/history-rss.htm

As interesting as the RSS story is, all you really need to know at this point is that your RSS feed is a critical ingredient in the success of your podcast. It's the mechanism by which folks subscribe to and automatically receive your new episodes.

Adding a Logo to an MP3 Podcast

2009-02-24T08:32:00.000-08:00

If you're at all serious about podcasting, you're going to want a logo. Adding a logo gives your podcast that extra bit of polish and recognition. And after you have a logo, you should embed it in every podcast you produce. However, it takes a few additional steps. Embedding images in MP3 files is a relatively recent phenomenon.

The original MP3 file specification did not include a way to attach metadata, such as the title, author, or copyright information. It wasn't until 1996 and the introduction of ID3 tags that metadata could be included in MP3 files. The original ID3 specification was fairly simple, including fields for title, album, year, genre, and comment. Over the years, the ID3 specification has grown to include much more, such as the track number on a CD, the composer, lyrics, and most important to this discussion, an embedded image, designed to contain album cover art. You can use this ability to embed a logo into your podcasts.

To add a logo to your podcast, you have to use an ID3 tag editor. Many are available, as a quick Internet search will reveal. As luck would have it, you probably already have one installed: iTunes. All you have to do is import your MP3-encoded podcast into iTunes and edit the ID3 tags via the Info window:

Open iTunes, and import your podcast by choosing Import from the File menu.
Find your podcast. If you're in library mode, you can sort by Date Added. This brings your podcast to the top of the list if you're in descending order.

Highlight your podcast, and choose Get Info from the File menu. This opens the Info window.

Note

If you're not seeing the Artwork tab, then your podcast isn't yet in a format that supports embedded artwork, for example an unencoded WAV file. This is why it's a twostep process: First encode your file to MP3, and then open it and add your logo.

Click the Artwork tab, and then click the Add button to browse for your logo graphic.

Select your logo graphic, and click the Open button. You should see your graphic displayed in the Info window. Your graphic can be in BMP, GIF, JPG, or PNG format and any size up to 300×300 pixels. You should make sure that it looks good at different resolutions, because it will be displayed at different sizes on different players. iTunes provides a handy slider bar that lets you preview what your logo looks like at various resolutions. If it doesn't look good when it is scaled, you should consider revising it until it does.

Caution

The 300 × 300 image size is not a strict limitation. However, using a larger resolution is not recommended because it may not be supported on portable media players, and it adds unnecessary payload to your podcast file.

Click the OK button to save your changes.

Your logo is now embedded in your MP3 file and will be displayed in iTunes, Windows Media Player, and on portable media player screens that display graphics.

Encoding H.264 video using QuickTime Pro

2009-02-02T08:32:00.000-08:00

You can export H.264 vide from QuickTime Pro in a number of ways. The simplest way is to use the iPod preset. This is perfect for creating iPod compatible files, but it gives you no control over any of the settings. You may want to tweak the settings a bit to suit your podcast, in which case you'll have to create your own encoding setting.

Using the iPod preset
Using the iPod preset is simple:

1. Open QuickTime Pro, and open the video to be encoded.

2. Choose Export from the File menu. This opens the Export window, shown in Figure 1

Figure 1: Export an iPod compatible video from QuickTime Pro using this preset.

3. From the drop-down menu, choose Movie to iPod (320×240).

4. Click Save. QuickTime Pro exports an iPod compatible H.264 video.

The only problem with using this preset is that it doesn't give you any control over any of the encoding options. You can't select a bit rate, a resolution, or anything else. Of course, it's guaranteed to work on an iPod, which is pretty handy. But the default bit rate is rather high, clocking in at over 800 kbps. This is fine for a short podcast, but if your podcast is longer than, say, 5 minutes, you're looking at a pretty serious download. You may want to dial the bit rate down to reduce the file size. To do this, you have to set your encoding settings by hand.

Encoding using custom H.264 settings
QuickTime also makes it easy to customize the encoding settings. There are a few more steps than using the iPod preset, but you have far more control over the output. Follow these steps:

1. Open QuickTime Pro, and open the video to be encoded.

2. Choose Export from the File menu. Again, this opens the Export window, as shown in Figure 2.

Figure 2: Here's how to get to the MPEG-4 video export settings.

3. Choose Movie to MPEG-4 from the Export drop-down menu.

4. Click the Options button to get to the video export settings. To begin with, this opens the MPEG-4 video settings, as shown in Figure 3.

Figure 3: Configure QuickTime MPEG-4 export video settings with this dialog box.

5. Select MP4 from the File Format drop-down menu.

Note QuickTime Pro defaults to MP4 (ISMA) for MPEG-4 output. ISMA stands for the Internet Streaming Media Alliance. Unfortunately the H.264 codec is not yet considered ISMA compliant (as of Fall 2006). This really doesn't mean anything. The H.264 codec is part of the MPEG-4 standard and will play back in any modern QuickTime player or iPod. For best quality, you should choose the MP4 option, not MP4(ISMA), so you can use the H.264 codec.

6. Choose H.264 from the Video Format drop-down menu.

7. Enter a bit rate for your file. Remember that the total bit rate is the video bit rate plus the audio bit rate.

8. Enter your screen resolution in the Image Size field. If you want iPod compatible files, choose 320×240.

9. Click the Video Options button to access the advanced encoding options. This opens the Advanced Video Settings window, shown in Figure 4.

Figure 4: Be sure to select Multi-pass encoding for the highest-quality results.

10. Choose Best Quality (Multi-pass) encoding mode, and click OK.

Note You may be wondering about the profiles restriction (Main versus Baseline) on this screen. In MPEG-4 encoding profiles define the "tools" that can be used to encode the video. Consequently these profiles also define the tools required to play back the encoded video. In this example, the Main profile provides more encoding tools than the Base profile. Since our goal is the highest quality video, we chose the Main profile.

The MPEG-4 standard is incredibly broad and frankly, not written in a way that a layman can understand. For a fantastic, concise, and fun-to-read explanation of the MPEG-4 standard, we recommend Damian Stolarz' Mastering Internet Video.

11. Now it's time to configure the settings for your audio. Select Audio from the second dropdown menu in the MPEG-4 Export Settings window. This changes the information displayed in the bottom half of the window from video settings to audio settings, as shown in Figure 5.

Figure 5: Configuring QuickTime MPEG-4 export audio settings

12. The first thing to choose is the audio codec you want to use from the Audio Format dropdown menu. In fact, the only codec offered for MPEG-4 encoding is AAC, which is just fine, because it offers great quality.

13. Next, select the desired bit rate from the Data Rate drop-down menu. A rate of 32 kbps should provide good quality.

14. If you're encoding spoken word content or want slightly higher fidelity, choose mono from the Channels drop-down menu.

15. The next available setting is the Output Sample Rate. This determines how much highfrequency information is contained in the final encoding. In general, the default setting works just fine. However, you can experiment with lowering the setting to get increased fidelity.

16. Finally, set your Encoding Quality to Best. This makes the encoding process take a little longer, but hey, your podcast is worth it.

17. Click OK to return to the Export menu, and then click Save to start the export/encoding process. You'll see the QuickTime Export progress window, shown in Figure 6, which gives you an idea how long the process will take. Depending on the length of your podcast, you may have time to grab a cup of coffee.

Figure 6: The QuickTime export progress window lets you know how long it's going to take.

Exporting MP3 audio from Audacity | Step by Step

2009-01-17T14:28:00.000-08:00

Exporting MP3 files from Audacity is simple, if somewhat limited. You have to set your desired bit rate in the Preferences window before you export, because you aren't given an option to adjust settings when you export. Here's how to set your preferred bit rate:

1. Open Audacity, and open your podcast audio file.

2. From the Edit menu, choose Preferences, as shown in Figure 1. This opens the Audacity Preferences window.

Figure 1: Use this dialog box to configure Audacity's MP3 export settings.

3. Click the File Formats tab.

4. Select your desired bit rate from the bit rate drop-down menu in the MP3 Export Setup section.

5. Click OK.

After you set your bit rate in the Preferences window, choose the Export as MP3 option from the File menu. That's all there is to it. Audacity doesn't offer the ability to do mono MP3 encoding or VBR-based encoding. As long as you don't want to do anything fancy, Audacity is a perfectly good encoding option.

Step-by-Step Encoding Examples | Podcast

2009-01-03T14:22:00.000-08:00

Now it's time to actually encode some files. This section demonstrates audio and video encoding using stand-alone encoders, editing platforms, and even iTunes. If your editing application isn't demonstrated, don't worry: It probably works much the same way. Let's start with iTunes, which really isn't an encoder, but it can do the job.

Tip You should always archive the high-quality version of your file so that you can re-edit or re-encode it later.

Encoding MP3 audio using iTunes
iTunes automatically encodes all imported audio. When you insert a CD and iTunes offers to import it, the audio bits are pulled straight off the CD and encoded into whatever format has been specified. The default setting is to encode using AAC. However, iTunes will also convert music in MP3 if you prefer, and will convert any file into an MP3 file. All you have to do is import the file into iTunes, and then convert it to MP3.

Setting MP3 encoding defaults
To use iTunes as an MP3 encoder, you have to set the default encoding to MP3. Follow these steps to set iTunes to import using the MP3 codec:

1. Open iTunes, and open the Preferences window by choosing Preferences from the iTunes menu (the Edit menu on a PC). You also can open this window using the keyboard shortcut Command+, (Ctrl+, on a PC).

2. Click the Advanced icon/tab, and select the Importing tab.

3. Select MP3 encoder from the Import Using drop-down menu.

4. Select your bit rate from the Setting menu. By default, the lowest setting offered is 128 kbps stereo. For most podcasts, this is a perfectly fine setting. If, however, you want to economize on your bit rate, you can adjust the settings by selecting Custom from the Setting drop-down menu.

5. Select a bit rate from the Stereo Bit Rate drop-down menu.

6. You can select a sample rate or leave this set to Auto. If your podcast ends up sounding a little crunchy or distorted, you can try lowering the sample rate to get better fidelity.

7. If you want a mono podcast, select Mono from the Channels drop-down menu.

Note If you select Mono encoding, the bit rate will be half of what you specified in the Stereo Bit Rate drop-down menu.

8. Click OK to close the Custom Settings menu, and then click OK to close the Preferences window. iTunes will now import files using the MP3 settings specified.

Importing and Encoding
To encode using iTunes, you must first import the file, and then convert the imported file. Importing couldn't be simpler:

1. From the File menu, choose Import.

2. Browse to find the file you want to encode, and click Choose (Open on PCs). The file is imported and is listed in your music library.

3. Find the file in your music library. Click it to select it, and then from the Advanced menu, choose Convert to MP3.

That's all there is to it! iTunes encodes it using the settings specified on the Importing tab of the Advanced menu. The iTunes music folder is easy enough to find, but if you want to encode to a specific location, you can change this setting in the General tab of the Advanced settings window.

Caution Be careful when you change your iTunes music folder; otherwise, you'll end up with your music library in two different folders. It's probably a good idea to change the music folder back to the default after you've finished your encoding.

Video Encoding | Learn Podcasting

2008-12-21T02:13:00.000-08:00

Video encoding is more involved than audio encoding. Raw video files are much larger than raw audio, so a much greater degree of compression is required. Modern video codecs also have benefited from fierce competition between the leading streaming media platforms, as well as the MPEG organization. Most encoding software packages include a number of presets that produce acceptable video quality. If you want to try to improve your quality by tweaking the encoding parameters, this section explains the basic options available to you and how they affect video quality.

Screen resolution
The most important decision you're going to make about your video podcast is what resolution (or screen size) you're targeting. This is largely determined by the bit rates you're targeting, which in turn are determined by your audience. The higher the bit rate, the larger your resolution can be.

Most encoding software programs let you specify any screen resolution you want. You can specify that you want the full 640×480 frame encoded at 100 kbps, and the encoder does the best job it can. What you end up with is a large screen full of blurry blocks moving around, because 100 kbps simply isn't enough to encode a resolution that large.

Table 1 lists some common video bit rates and suggested screen resolutions. Note that the resolution is largely dependent on the content of your video. If you have lots of motion in your podcast, you have to use either a higher bit rate or a smaller resolution to achieve acceptable video quality. If your podcast is relatively static and you filmed using a tripod, you may be able to try slightly larger screen sizes.

Frame rate
Another parameter you can adjust is the frame rate. NTSC video is shot at 30 frames (actually 60 fields) per second. However, for low action content, you may be able to get away with a lower frame rate. For example, interview footage often looks just fine at 15 frames per second. Higher action content requires the full frame rate for smooth motion.

Adjusting the frame rate affects the overall clarity of the video, because no matter how many frames per second you're encoding, you always have a fixed bit rate at which to encode. If you're encoding at 300 kbps, you can spread those 300 kilobits over 30 frames or 15 frames. Obviously, if you're only encoding 15 frames instead of 30, you can dedicate more bits per frame, and the result is a higher-quality frame. However, this may be a false economy for high action content.

Remember how video encoding is done. First, a key frame is encoded, which is followed by a number of difference frames. High action content has lots of motion and, therefore, lots of difference from frame to frame. If you drop the frame rate to try to economize, the encoder drops frames and doesn't encode them. There are certainly fewer frames to encode, but the differences between them are greater! This is illustrated in Figure 1.

Figure 1: When encoding at a reduced frame rate, the increased differences between frames may negate the gains of encoding fewer frames.

If your programming has very little motion in it, such as talking head content, you may see an improvement in quality by dropping the frame rate. However, if you have lots of action in your podcast, leave the frame rate as is. To get higher video quality, you'll have to either encode at a higher bit rate or reduce your screen resolution.

Note The frame rate of NTSC video is actually 29.97 frames per second, although 30fps is often used as shorthand.

Bit rate
Along with the screen resolution, the other important choice you have to make is the bit rate of your podcast. The bit rate determines the quality and the file size, and it's the gating factor for the resolution. The bit rate you choose is determined to some extent by your audience, and the length of your podcast. The idea is that you don't want your audience to have to wait forever to watch your podcast. If the podcast is being downloaded in the background by an aggregator, then this isn't an issue. But many video podcasts are watched on Web pages. The user clicks a link and expects to see something in a reasonable amount of time.

Because most podcasters host their podcasts on a Web server, most video podcasts are progressively downloaded. Progressively downloaded videos have to preload a bit before they start playing back. The amount of preload is determined by the embedded player. The player knows how big the video file is and calculates how long the video will take to download. The player also knows how long the video is and tries to figure out how soon it can start playing the video so that by the time the playback reaches the end, all the video will have downloaded.

Let's say you've encoded your video at 300 kbps, which is a pretty standard bit rate. Most broadband connections can sustain this bit rate consistently, so as the video starts downloading, the player realizes in a few seconds that the data is being downloaded fast enough to begin playback. The total wait time for your audience is minimal.

Now let's take the same podcast and encode it at 500 kbps. Let's say it's a 1-minute podcast. The total file size is going to be approximately 30,000 kilobits (we'll stay in the world of bits because the math is easier). If the user's connection can sustain 300 kbps, it takes 100 seconds to download the entire file. If the file is 60 seconds long, that means the user has to wait 40 seconds before playback can begin. This is probably a little excessive, unless your audience is very dedicated. And this is if your podcast is only a minute long. For each additional minute, the audience is forced to wait an additional 40 seconds. This can get out of hand quickly.

If you're doing longer form content, longer than 5 minutes, then you should choose a bit rate that your users can receive in more or less real time. We can take a hint from streaming media sites here, who commonly target 300 to 450 kbps. If you're worried about bandwidth costs, you can choose a lower bit rate. Your video quality might suffer a bit, but if you can't afford your bandwidth bill, you won't be able to continue podcasting!

Audio bit rate
Of course, the bit rate we have been talking about up to this point has been the total bit rate of your podcast. After you choose your target bit rate, you have to decide how much of that bit rate you're going to allot to the audio stream. There are audio codecs at bit rates from 5 kbps up to hundreds of kilobits per second. How much should you give your audio stream?

One thing to remember is that audio tells the story. Audio is what draws the audience in and keeps them attentive. Think about it: When you're watching television at night with friends and a commercial comes on, what happens? If you're like most people these days, someone punches the mute button on the remote, the room immediately comes to life with conversation, and people take the opportunity to grab something from the refrigerator. When the commercial break is over, the audio is un-muted, and everyone pays attention to the program again.

The same holds true for your podcast. It's worth making sure that your audio quality is good, because people will watch low quality video if the audio sounds good. They won't watch good quality video if the audio sounds bad.

A fairly safe rule is to use about 10 to 20 percent of your total bit rate for audio. At higher bit rates, you can stay toward the bottom of that scale; at lower bit rates, stay toward the top. Another suggestion is to avoid the lowest audio bit rate settings. The difference between a 5 kbps audio feed and an 8 kbps audio feed is huge; those extra 3 kbps won't add much to your video quality.

Multi-format encoding

2008-12-11T05:23:00.000-08:00

In the beginning, podcasts were audio only and always encoded using the MP3 codec. But as people have started to realize the potential for video podcasting and portable media player displays have improved, the possibilities for podcasting have multiplied. The problem is that most of these enhanced opportunities come at a price, and that price is compatibility. Enhanced podcasts designed for the iPod do not play on other portable media players. Podcasts encoded using the Windows Media format for compatibility with the "Plays For Sure" portable players do not play on the iPod. And if you want to offer a video image larger than 320×240, it may or may not play back on portable media players.

So what can a podcaster who wants to push the envelope do? The best approach is to offer a number of formats and let your audience choose which version they'd like to subscribe to. Of course, if you're offering multiple formats, you're no longer encoding a single version of your podcast; you may be encoding three or four. For example, if you really want to offer every possible choice, you might offer the following:

An MP3 version for older media players

An enhanced iPod version with images

A 320×240 video version encoded in Windows Media

A 320×240 video version encoded in QuickTime H.264

A 640×480 video version encoded in Flash format for Web viewing

Granted, this example may seem excessive, and the chances that someone would encode into so many different formats are pretty slim. However, it's not out of the realms of possibility. Rocketboom, one of the most popular video podcasts, is encoded into four different formats. If you want the largest possible audience and want to stay at the cutting edge of podcasting technology, you're going to have to encode multiple versions. This is where a multi-format encoder comes in handy.

Tip If you're offering more than one format, offer separate RSS feeds for each so people can subscribe to their favorite format.

Multi-format encoders enable you to choose a single source file and output to multiple formats. These encoders usually allow you to set up encoding presets, so you don't have to re-enter the encoding settings every time you encode. Many multi-format encoders also allow you to preprocess your original master, so if you want to do color correction or resizing, it can be done at the encoding stage.

Some multi-format encoders offer automatic batch processing, where files placed into a specific directory are automatically processed and encoded. You can streamline your production chain if you're using a multi-format encoder with batch processing. This allows you to concentrate on your programming and let the batch processing take care of the rest.

A number of multi-format encoding solutions are available, including these popular ones:

Sorenson Squeeze: The Sorenson Squeeze Compression Suite offers MP3, AAC, QuickTime, Windows Media, and Real formats (Mac users must have the Flip4Mac plugin installed to get Windows Media capabilities). You can add Flash encoding with an additional plug-in (see Figure 1), or by purchasing the Squeeze Power Pack.

Figure 1: Sorenson Squeeze

Canopus Procoder: The Express version offers QuickTime, Windows Media, and Real support. The full 2.0 version also offers MP3 encoding, and Flash encoding if you have Flash MX installed.

Telestream FlipFactory: This offers MP3, QuickTime, Windows Media, Real, and Flash support. It also supports 3GPP (mobile phone format) with an additional plug-in.

Digital Rapids Stream: The basic version offers QuickTime, Windows Media, and Real support. The Pro version adds MP3 and Flash support. All Digital Rapids software requires Digital Rapids capture cards.

Encoding Via Your Editing Platform

2008-11-30T17:17:00.000-08:00

If you've invested in a decent audio-editing or video-editing platform, chances are good that you'll use your editing platform to do your encoding. Most include a variety of export options. (You'll also want to export a broadcast-quality master for archival purposes, of course.) If your master includes lots of processing and complicated editing, you may want to render the broadcast-quality master and then encode using an encoding application or multi-format encoder, instead of doing all the processing twice. For most podcasts, exporting an encoded master directly from your timeline is probably easiest.

Audio
Most audio-editing platforms offer MP3 encoding. Many also offer encoding in a number of other formats:

Audacity (Windows, Mac, Linux): Offers MP3 and Ogg Vorbis export

Peak (Mac): Offers MP3 and AAC export

Garage Band (Mac): Offers AAC export, which is fine for iPods, but does not support MP3 export

Sound Forge (Windows): Offers a number of export options, including MP3, Ogg Vorbis, Windows Media, and RealAudio (see Figure 1)

Figure 1: Sound Forge offers a large number of export options.

Audition (Windows): Also offers a wide variety of support, including MP3, Windows Media, and RealAudio

Video
Video-editing platforms also offer fairly rich export options:

Final Cut Pro (Mac): Offers QuickTime H.264 support

iMovie (Mac): Offers QuickTime H.264 support, including a preset for iPods

Adobe Premiere (PC): Offers Flash, QuickTime, Windows Media, and RealVideo support

Sony Vegas (PC): Offers QuickTime, Windows Media, and RealVideo support

Ulead Video Studio (PC): Offers QuickTime, Windows Media, and RealVideo support, and includes output templates for iPods and SmartPhones

Making Format Choices | Podcast

2008-11-23T17:15:00.000-08:00

Because this is a technical manual that includes business advice concerning podcasting, you might expect that we would tell you which format is best for your podcast. Unfortunately, that's not something we can do. Things were much simpler when a podcast meant an MP3 file that was automatically downloaded to a desktop and transferred to an iPod. Now that the term podcasting has expanded to include a variety of portable media players and video, the podcasting format wars have begun.

The territory that is being fought over is very valuable. As podcasting continues to grow in popularity and people continue to time-shift their media consumption habits, the large media conglomerates are scrambling to catch up to the thousands of already-successful podcast brands that have been established. Similarly, the portable media player manufacturers are fighting tooth and nail for control of the player market. Control the player, and you control access to the millions of people who are discovering podcasting.

To some extent, we can learn from streaming media. The industry that RealNetworks pioneered quickly became a three-horse race when QuickTime and Windows Media entered the field. Flash was a late entry to the field and is making a dent in everyone's market share numbers. Experts have talked about the imminent demise of MPEG4 or RealNetworks, but the reality is that there seems to be room for all the streaming formats, and none of them is going away anytime soon.

The same probably holds true for podcasting. The iPod has a massive share of the portable media player market, but with Microsoft coming out with a portable media player as this book is being written, that is sure to change. As the term podcasting has broadened, so has the way people listen to and watch podcasts. Studies have shown that half of all podcasts are actually watched on a desktop or laptop computer, not a portable media player.

Because the podcasting industry is still in its infancy, the situation is likely to continue to change. There is no easy answer to the format question, nor one likely in the short term. However, in the interest of helping you make a decision, we can point out a few things to help you cut through the media hype:

If you're producing an audio podcast, MP3 gets you the widest compatibility.

If you're producing a video podcast, QuickTime is a good choice because it's compatible with the iPod and anyone who has iTunes installed.

If you don't care about portable media players and are offering video playback via your site, Flash is a good option because it has good cross-platform support.

Windows Media has better video quality than QuickTime and Flash, and there are a heck of a lot of PCs out there.

RealNetworks are making huge inroads into the mobile market, particularly in Europe.

The best way to figure out what format is best for your podcast is to start off simple, possibly offering only a single stream option. Monitor your e-mail and your blog comments. After you've developed a bit of an audience, ask them what they prefer. Podcasting is still a relatively intimate broadcast medium, and the way to make loyal audience members is to give them what they want.

Basic Encoding Techniques

2008-11-17T05:29:00.000-08:00

Whether you encode your podcast by exporting directly from your editing platform or by using a stand-alone encoder, you can specify a number of parameters. You may have only a few choices if you're using encoding presets, or you may have the opportunity to specify exactly how you want your podcast encoded.

In the early days of low bit-rate encoding, back when people were connected to the Internet via slow modems, encoding technology was limited and required lots of tweaking to extract the best quality. Now, ten years later, codec technology and Internet connection speeds have improved so much that encoding high-quality podcasts should be within everyone's reach.

This is particularly true of audio podcasts. Modern codecs such as RealAudio and Windows Media Audio are capable of attaining FM-mono quality at a mere 32 kbps. The MP3 codec lags behind in quality, but because you can safely encode your podcast at 128 kbps, you should not have any quality issues.

Video is a little trickier. Assuming the majority of your audience is on a broadband connection, your video quality is limited by available bandwidth. Although you can't expect DVD quality at these bit rates, there's no reason why you can't create a perfectly acceptable video experience. This chapter helps you choose settings that should do the job. Let's start off with the easy stuff — audio encoding.

Audio Encoding

Audio encoding is easy, for a number of reasons. Raw audio files are large, but nowhere near as huge as video files. Therefore, the amount of compression that is needed to reduce them to a size that is suitable for Internet distribution is not excessive. Audio codec technology has progressed to a point where low bit rate encoding produces very good results. Podcasting reaps the benefits of ten years of cutthroat competition between RealNetworks and Microsoft, and the progress made by the MPEG organization with AAC encoding.

Because modern codecs sound so good, you really don't need to do much tweaking when you're encoding audio. You really have to decide only three things: whether to encode in stereo or mono, whether to use a speech or a music codec, and what bit rate to use.

Mono versus stereo
The first thing to decide is whether to encode your podcast in stereo or mono. If your program is predominantly interviews or spoken word, encode in mono. Mono encodings are always higher fidelity at a given bit rate, because only a single channel is encoded instead of two. If you're encoding in mono, you can use a lower bit rate and get the same quality or you can get better quality than a stereo encoding at the same bit rate.

If your content is predominantly music, you should encode in stereo, although it isn't strictly necessary. Even though music is recorded in stereo, most of the content is right in the center of the mix. The lead vocal, the snare drum, the bass drum, all will be right in the center of the speakers. And watch where you place your speakers. If you aren't sitting directly between the speakers, you aren't experiencing the full stereo effect anyway. However, one good reason to target stereo if you're playing music is that half your audience may be listening on headphones, which exaggerates the stereo effect.

Speech versus music
The next thing to decide is whether to use a speech codec or a music codec. If you're encoding an MP3 file, you don't have a choice. MP3 is a music codec. The good news is that MP3 is perfectly suitable as a speech codec as well, provided the bit rate is high enough.

Speech codecs can take special shortcuts during the encoding process due to the nature of speech content. With speech, the dynamic range tends to be very limited, as is the frequency range. After you start talking, the chances are good that you'll continue to speak at roughly the same volume and in the same register. Knowing this, a speech codec can make intelligent decisions about how to encode the audio.

Music content, on the other hand, has a wide dynamic and frequency range. There are bass drums and bass guitars, as well as crashing cymbals and violins. The shortcuts that a speech codec takes are completely unsuitable for encoding music content.

So the choice is fairly obvious: If you're encoding content that is speech only, you can encode at very low bit rates and still achieve high quality using a speech codec. However, for most applications, a music codec is perfectly appropriate.

Bit rates, sample rates, and quality equivalents
The most important decision to make about your audio podcast encoding is what bit rate to use. The bit rate determines the eventual file size of your podcast, which in turn determines how long it takes to download. The bit rate also determines the fidelity of your podcast. The higher the bit rate, the higher fidelity your podcast is.

The listed audio bit rates range from 20 kbps to 256 kbps. If you're producing audio-only podcasts, you should target somewhere between 64 kbps and 128 kbps. If you're encoding predominantly speech, you can safely stay at the low end of that; if you're encoding music, you may want to stick to the higher end of the spectrum.

Note At the end of the day, you know best how you want the podcast to sound. Try encoding at a couple of different bit rates, and see which one sounds best to you.

The other thing you may be able to set is the sampling rate. The sampling rate determines how much high-frequency information is encoded. For example, CD-quality audio uses a sample rate of 44.1 KHz, to capture the full 20–20,000 Hz frequency range. The sampling rate has to be at least double the highest frequency you're trying to capture. Depending on what bit rate you're targeting, you may be offered a few different sampling rates.

The interesting thing about sampling rates is that a higher sampling rate isn't necessarily better. The sampling rate determines how often the incoming audio signal is sampled, so it determines how much audio the encoder has to try to encode. If you set a higher sampling rate, you're telling the encoder to try to encode more high-frequency information, but the encoder may have to sacrifice the overall quality of the encoding. Essentially, the sampling rate determines the trade-off between the frequency range and the fidelity of the encoding. At a given bit rate, an encoder can offer higher fidelity with a reduced frequency range or reduced fidelity with a higher frequency range.

We suggest that you choose a lower sampling rate, thereby allowing the encoder to create a higher fidelity version of your podcast. There is very little information above 16 KHz in most audio programming, and most people don't have speakers that reproduce it faithfully anyway. Therefore, choosing a 32 KHz or 22 KHz sampling rate should provide more than enough high-frequency information.

Other Encoding Formats | Podcast

2008-11-11T17:09:00.000-08:00

MP3 is perfect for audio podcasts, but you may want to work in other formats for a number of reasons. Many portable media players now include color displays. Enhanced podcasts are appearing to take advantage of these color displays that include graphics along with the audio. Enhanced podcasts can also include links for people who are watching the podcast on a browser. Enhanced podcasts also feature chapters, so people can quickly skip to the next or previous section of your podcast.

You can create enhanced podcasts using the QuickTime and Windows Media formats. Of course, enhanced QuickTime podcasts play back only on iPods or in iTunes, and enhanced Windows Media podcasts play back only in Windows Media player and Windows Media compatible portable media players. Another enhanced podcast format is the Audible format, which was developed for audio books. The Audible format includes the chapters feature, as well as the ability to store a bookmark, so that if you stop listening in the middle of a podcast, the next time you listen the podcast starts where you left off. Because the Audible format has been around for so long, it is widely supported by almost every portable media player, as well as in iTunes, Windows Media Player, and RealPlayer.

If you're creating a video podcast, a number of different formats are available, including QuickTime, Windows Media, Real, and Flash. Video podcasts have the same compatibility issues as enhanced podcasts, which means limited compatibility across portable players, and they require that the appropriate player software is installed on the audience's computer.

Caution People are weird. Talk to one person and he'll tell you why he would never install media player A on his machine, while the next person swears by player A and is convinced media player B is the devil's spawn. To some extent, these people split across platform lines (Mac users swear by QuickTime, Windows users Windows Media, and Flash users hate everything else), but not always. Each media format has its strengths and weaknesses. If you're planning on a video podcast, you should support at least two formats. Regardless of which formats you choose, plan on getting disgruntled e-mails and blog comments from crazed audience members. You can't please everyone.

Another reason to consider alternative formats is if you want to protect your podcast files using Digital Rights Management (DRM). DRM lets you place restrictions on your podcast, for example letting only paid subscribers listen to it. Not all formats support DRM. Because most podcasts are free and most podcasters want as many listeners as they can get, very few podcasts use DRM. This may change as people begin charging for their podcasts.

If you're going to offer your podcast in an alternative format, you may need to download and install encoding software (see Figure 1). Many of these formats will be included in your audio or video editing platforms, but if not, the software is generally available for free from the manufacturers.

QuickTime: iTunes will encode in the AAC and MP3 formats and exports videos to an iPod compatible format, but if you want to tinker with the encoding settings, get QuickTime Pro. You can upgrade any copy of QuickTime to the Pro version for a mere $29.

http://www.apple.com/quicktime

Windows Media: The Windows Media Encoder is available as a free download from the Microsoft site.

http://www.microsoft.com/windowsmedia

Note Microsoft has recently dropped support for Windows Media encoding on the Mac. However, Mac users can encode in Windows Media using products from Flip4Mac:

http://www.flip4mac.com/wmv.htm

Helix RealProducer: If you're considering the Real format, you need the RealProducer.

http://www.flip4mac.com/wmv.htm

Unfortunately, if you're targeting mobile phones (where the Real format is strongest), you need Helix Producer Mobile, which is incredibly expensive. If it's any consolation, you can download a trial version that's good for 30 days.

Flash: To encode into Shockwave Flash (.swf) or streaming flash (.flv), purchase the Flash authoring tool. Several multi-format encoders also offer Flash support.

http://www.adobe.com/ flashpro/

Audible: Audible doesn't make their encoding software publicly available. Instead, you have to upload your original MP3 file to their Wordcast service, and they do the encoding for you.

http://wordcast.audible.com/

Figure 1: The Windows Media Encoder is available for free from Microsoft for the PC platform (Mac users must use Flip4mac).

MP3 Encoding Tools

2008-11-03T05:05:00.000-08:00

If you're producing an audio podcast, you're probably best producing it in the MP3 format. Although it isn't the best audio codec available, it is by far the most compatible and plays on virtually any computer or portable media device. It may not have all the bells and whistles of other formats, but your audience is far less likely to have technical issues, which means you'll get fewer negative comments on your blog.

Virtually any editing platform you're working on should have built-in MP3 encoding capabilities, but on the off chance that it doesn't, a number of standalone MP3 encoding applications can get the job done; one such application is shown in Figure 1.

iTunes: iTunes isn't really an encoding application, but it converts audio files to mp3 on import if you choose to do so in your preferences.

LAME-based encoders: Despite the ironic origin of the name (Lame Ain't an MP3 Encoder), LAME is an open source MP3 encoding library that is used in almost all free MP3 encoding applications. There are probably hundreds of these available; google "MP3 encoder" and see for yourself.

Figure 1: WinLAME is one of many free MP3 encoders available.

Encoding Tools

2008-10-27T05:04:00.000-07:00

You should understand clearly by now that your podcast must be encoded in a format that is suitable for Web distribution. To do this, either you must use a standalone encoding application or export directly from your audio-editing or video-editing software. If you want to be a real podcasting hot shot, you may want to encode an enhanced podcast or offer video podcasts for various portable media players. If so, you'll probably want to invest in a multi-format encoding solution. In addition to enabling you to encode a single file into a number of different formats, they let you tweak all the encoding settings so you can get the highest possible quality encoding.

Your decision about which encoding software to use will be based on a number of factors:

Are you encoding audio or video podcasts (or both)?

If you're producing audio podcasts, do you want maximum compatibility across media players, or would you rather produce a cutting edge podcast with features that may not work on all players?

If you're producing video podcasts, how many formats do you want to produce?

Podcasting purists consider podcasts to be MP3 files. But video podcasts are becoming increasingly popular, and there are serious cross-compatibility issues with video podcasts. Portable media players support different codecs, and some people may not have the required player software installed to watch your video podcast on their computer.

We'll talk about these issues a little later in the chapter. To begin with, let's start with the simplest case. We'll assume that you're producing an audio podcast, and for maximum compatibility you're using the granddaddy of all podcast formats, the MP3 file.

File Formats : MP3, QuickTime, Windows Media, RealMedia, Audible

2008-10-07T04:07:00.000-07:00

Knowing about codecs is important, because the codec determines the final quality of the podcast. However, you also have the problem of file formats. The file format dictates how the audio and video information is packaged. Some codecs can fit into a number of different file formats. The problem is that most proprietary systems such as QuickTime, Windows Media, and Real use proprietary file formats to hold the encoded audio and/or video information. File formats are highly guarded trade secrets and the main cause why files are not interoperable between players. However, the file formats also enable the proprietary systems to offer additional functionality. These are the most common file formats you'll encounter:

MP3: MP3 is actually a codec, not a file format. The file format is actually MPEG. (MP3 stands for MPEG II, Layer 3.) MPEG files are almost universally playable and the reason most folks use MP3 to encode and distribute their podcasts.

QuickTime: The QuickTime file format is the earliest multimedia file format and the basis of the MPEG 4 file format. QuickTime files also are almost universally playable, though the codecs inside may not be.

Windows Media: The Microsoft standard, Windows Media obviously plays back on any PC and a large number of portable media devices, but not the iPod.

RealMedia: RealNetworks' file format, this requires the RealPlayer. It is supported on many cell phones.

Audible: The Audible file format was designed specifically for audio books, and consequently supports saved playback position, chapter marks, book marks, and other desirable features. Because it has been around for quite some time, it has lots of support in proprietary players and portable media players.

As mentioned earlier, your choice of codec and file format depend on what audience you're trying to reach and what features you want to use. For most folks, MP3 works well for audio because it plays on virtually every computer system and portable audio player. It doesn't support book marks or chapters, but most podcasts are short enough that they don't require that functionality.

For video, most folks are using QuickTime, again because of the near-universal support and because of the iPod, of course. However, some people are starting to experiment with other formats to see what they can do with the advanced functionalities they offer. Always offer the MP3 and QuickTime versions. If you want to play around with the advanced formats, offer them in addition to your standard podcast versions.

Video Codecs

2008-09-25T04:05:00.000-07:00

Video codecs are much easier to distinguish from each other than audio codecs. Video quality is still on the rise, with each new codec release improving quality. However, most video codecs are proprietary, meaning they won't play back on other players. If you're embedding your podcast in a Web page, then you can do all sorts of checking via JavaScript to see whether people have a certain plug-in installed. If you're targeting portable media players, then you'll have to be careful about which video codec you choose.

H.264: Part of the MPEG4 standard, H.264 is quite an improvement and, what's more important, is the video standard supported by the iPod.

Windows Media Video (WMV): Currently at version 11, the WMV codec provides outstanding quality, along with lots of advanced functionality. It is also supported by the "Plays for Sure" family of portable media players.

RealVideo (RV): Recently voted the best video codec by http://StreamingMedia.com author Jan Ozer. RV provides lots of advanced functionality, but is not supported on the iPod or the "Plays for Sure" devices. However, RV is supported on a number of cell phones.

OGG Theora: The sister project to the Ogg Vorbis audio codec project. Theora videos play back in a number of open source players, as well as the RealPlayer and QuickTime, though they require the installation of an additional component.

Audio Codecs : Speech optimized codecs & Music optimized codecs

2008-09-19T15:35:00.000-07:00

Now that you know how codecs work, it's time to see what codecs are available to podcasters, how they differ, and why you might want to use them. The first thing to consider is whether you're planning on using music in your podcast. If you are, then you definitely want to use a codec that is suited for music. If your podcast is just speech, then you may want to consider using a speech codec, because you'll be able to get very good quality at ridiculously low bit rates, thereby saving you money on bandwidth.

Choosing a codec is a tricky business. Newer codecs offer better quality, and some offer advanced functionality such as book marking and embedding images. However, many of the newer codecs play back only on a limited number of portable devices. If you want the latest and greatest features, but also want to cater to the widest possible audience, you may want to consider encoding to multiple formats.

Music-optimized codecs
As mentioned previously, if you're going to include any music at all in your podcast, you must use a music codec. Luckily, you're spoiled for choice. Here's a list of possible candidates:

MP3: The granddaddy of them all. MP3 wasn't initially designed as a low bit rate codec, so other codecs sound much better at low bit rates. It also does not support book marking. But just about every computer and portable media device in the world will play back an MP3 file.

Advanced Audio Coding (AAC): The new and improved MPEG audio codec, meant to replace MP3. The only problem is that it isn't supported on some portable players. AAC enables advanced features such as book marking and embedded images.

Windows Media Audio (WMA): The standard on Microsoft PCs. It has many advanced features such as markers, script commands, and embedded links. WMA is not supported on iPods, though it is supported on the "Plays for Sure" family of portable media devices.

RealAudio (RA): The default audio codec of the RealPlayer, which offers embedded links and script commands. It is supported on a number of cell phones.

OGG Vorbis: An open source audio codec offering excellent quality. Unfortunately, Vorbis isn't supported by many of the proprietary players, nor by the iPod.

Speech-optimized codecs
If your podcast doesn't include music, you should consider using a speech codec. They provide better quality at the same bit rate as a music codec, or the same quality at a reduced bit rate.

Audible Audio (AA): Developed for the first portable digital media player, which was released by Audible and designed to play back audio books. AA supports a number of advanced features such as book marking. Unfortunately, Audible doesn't make an AA encoder publicly available.

ACELP.net: The granddaddy of voice codecs. In fact, the AA format is based on the ACELP.net codec. ACELP.net is supported by both the Windows Media and Real players.

OGG Speex: Another branch of the OGG open source project, specializing in low bit rate speech compression.

Windows Media Audio Voice Codec: During Windows Media encoding you can specify that you're encoding voice content, and the Windows Media encoder will use a voiceoptimized codec.

How video codecs work

2008-09-13T15:31:00.000-07:00

Video codecs also have improved dramatically. The challenge of encoding video, however, is orders of magnitude more difficult than encoding audio. We found that a minute of CD-quality audio is about 10 MB before it is encoded. That's nothing compared to video. If the video is being digitized in the RGB color space, each pixel uses 24 bits (8 for red, 8 for green, and 8 for blue). So that means a frame of video uses:

720 lines * 486 pixels * 24 bits/pixel = 8,398,080 bits =
1,049,760 bytes
= 1MB per frame of video

To get the file size for a 20-minute podcast, we remember that there are 30 frames per second, so:

1MB * 30 frames * 60 seconds * 20 minutes = 36000MB = 35.15 GB

Yes, you read that right. A 20-minute podcast can chew up an entire hard drive, or at least a good chunk of one. Of course, the preceding calculations assumed uncompressed RGB video, and most podcasts are done using a DV camera. Because DV video is compressed at a 5:1 ratio, you're only looking at around 7 GB for your 20-minute podcast. But imagine downloading a 7 GB file! That's not going to happen in a flash. It's going to take a good long time.

So the first thing we have to consider is reducing the resolution of the video so there are fewer pixels to encode in each frame. If you resize down to 320×240, you've reduced the file size by 75 percent. You also can cut the frame rate in half for further data reduction. But it turns out that this is still nowhere near the amount of reduction required to be able to deliver this video reliably and in an acceptable amount of time (and without breaking your bandwidth budget). To do this, video codecs rely on perceptual coding, using inter-frame and intra-frame encoding.

Intra-frame encoding is encoding each frame individually, just as you would when you shrink an image using a JPEG codec. Inter-frame encoding is a more sophisticated approach that looks at the difference between frames and encodes only what has changed from one frame to the next. This is illustrated in Figure 1.

Figure 1: Inter-frame compression encodes only the differences between frames.

To be able to encode the difference between frames, the codec starts off by encoding a full frame of video. This full frame is known as a key frame. After the key frame, a number of difference frames are encoded. Difference frames, unsurprisingly, encode only what has changed from the previous frame to the current frame. The codec encodes a number of difference frames either until a scene change or when the amount of change in the frame crosses a predetermined threshold. The sequence of key frames and difference frames is illustrated in Figure 2.

Figure 2: Inter-frame compression uses a sequence of key frames and difference frames.

The combination of reduced screen resolutions, frame rates, intra-frame compression, and interframe compression is sufficient to create satisfactory video experiences at amazingly low bit rates. Although no one would want to pay to watch it, you can create video files at bit rates as low as 32 Kbps. Of course, we recommend using ten times that much for your video podcast. At 300 Kbps and above, you can deliver an entirely satisfactory video experience. It won't be perfect, but it should be more than adequate.

Codec side effects
No codecs are perfect. Even when codecs claim to be transparent, an expert somewhere can tell the difference. At higher bit rates, the differences between the original and the encoded version are minimal. As the bit rate decreases, however, the differences become easy to spot. Perceptual codecs attempt to remove things that we won't notice, but unfortunately they're not always successful.

Because so much information must be removed from files, you get less of everything in the encoded version of your file. The frequency range is reduced, as well as the dynamic range. If you're encoding video, you have a smaller screen resolution and possibly a decreased frame rate. If that's not enough, you also see or hear artifacts in your podcast.

Artifacts are things that weren't in the original file. In encoded audio files, artifacts can be heard as low rumbling noises, pops, clicks, and what is known as "pre-echo," which gives speech content a lisping quality. For video files, you may notice blocking artifacts, where the video is broken up into blocks that move around the screen. You also may see smearing, where the video image looks muddy and lacks detail.

If your podcast has audible or visible artifacts, you should check your encoding settings. Audio podcasts in particular should not have artifacts; you should be more than capable of producing a high quality audio podcast. Video, however, is a different matter. If you're delivering a 320×240 video podcast encoded at 300 Kbps, chances are good that you'll encounter a few artifacts. They shouldn't interfere with the ability to enjoy your podcast. If they do, you'll need to revisit your equipment or your shooting and editing style, or simply encode your video podcast at a higher bit rate.

How perceptual codecs & audio codecs work

2008-09-05T15:29:00.000-07:00

Perceptual codecs take advantage of how we actually perceive audio and video, and use this information to make intelligent decisions about what information can safely be discarded. Perceptual codecs are by definition lossy because of this. The original cannot be recreated from the encoded file. Instead, an approximation that attempts to retain as much fidelity as possible is constructed. The idea is that we won't notice what has been discarded.

Our ears are extremely sensitive. We can hear from 20Hz to 20,000Hz and sounds over a wide dynamic range, from a whisper to a scream. We can pick out a conversation at the next table in a crowded restaurant if the topic happens to catch our ear. We can do this because our brains filter out the information that is not of interest and focus on the rest. Our brains effectively prioritize incoming sound information.

For example, even a quiet classroom has plenty of sounds, such as the hum of air conditioning, people shuffling papers, and the teacher lecturing at the front. If someone sneezes in the room, for that split second, everyone notices the sneeze and nothing else. The sneeze is the loudest thing in the room and takes precedence over everything else.

Similarly, our eyes can take in a wide range of visual information, the entire color spectrum from red all the way through purple, and from very dim environments to very bright environments. Our field of vision is approximately 180 degrees from left to right. What we actually pay attention to, though, is much more focused. In general, we pay more attention to things that are brightly colored and things that are moving.

Perceptual codecs use this information to make better decisions about what information in audio and video files can be discarded or encoded with less detail. Perceptual codecs prioritize the loudest frequencies in an audio file, knowing that's what our ears pay most attention to. When encoding video, perceptual codecs prioritize bright colors and any motion in the frame.

At higher bit rates, perceptual codecs are extremely effective. A 128 kbps MP3 file is considered to be the same apparent quality as a CD and is only one-tenth the size of the original, which is pretty incredible if you think about it. Some of the savings is encoding efficiency, but the majority of it is perceptual encoding. As the bit rate is lowered and the codec is forced to discard more and more of the original information, the fidelity is reduced and the effects of perceptual encoding are more audible. Still, you should always balance the required fidelity of your podcast with the realities of bandwidth and throughput.

How audio codecs work
Audio codec technology has made spectacular advances in the last few years. It's now possible for FM quality to be encoded in as little as 32 kbps (in mono, that is). Modern codecs such as Windows Media, Real, and QuickTime AAC can achieve CD quality in approximately 64 Kbps. How do they do it?

The idea is to capture as much of the frequency and dynamic range as possible and to capture the entire stereo image. However, given the target bit rate, the codec usually determines what a reasonable frequency range is. Files that are encoded in mono are always slightly higher fidelity, because the encoder worries about only one channel, not two.

Another economy can be made if the codec knows that it will be encoding speech. Speech tends to stay in a very limited frequency and dynamic range. If someone is talking, it's unlikely that her voice will suddenly drop down an octave, or that she'll start screaming for no reason. Knowing this, a codec can take shortcuts when encoding the frequency and dynamics information.

Caution Don't try to encode music using a speech codec. The shortcuts a speech codec uses are totally unsuitable for music, because music uses a very wide frequency range and is generally very dynamic. If you encode using a speech codec, it sounds awful. So don't do it.

After the frequency range has been determined, the codec must somehow squeeze as much information as possible into the encoded file and decide what can be discarded. Perceptual audio codecs use the concept of masking to help make that decision. If one frequency is very loud, it masks other frequencies, so the codec can safely discard them because we wouldn't perceive them.

This is why all background noise must be minimized in your original recordings and your programming must be nice and loud. This ensures that the codec doesn't discard any of the programming information.

Codecs Overview : How codecs work

2008-08-28T17:27:00.000-07:00

We know that encoded files are much smaller than raw media files; the question is how do encoders achieve this file size reduction, and why does the quality suffer?

At the heart of all encoding software lies the codec. Codec is a contraction of coder-decoder (or compressor-decompressor), and is the software algorithm that determines how to shrink a file to a usable size. You're probably already familiar with a number of codecs, though you may not be aware of it. For example, most digital cameras take pictures that are compressed with the JPEG codec. If you've ever used a photo-editing program to reduce the size or quality of your photos before you put them online, you've been adjusting the parameters of the JPEG codec. StuffIt and WinZip use codecs to compress files before they're sent across the Internet or put on installation CDs.

There's a key difference, however, between the JPEG codec used to compress photos and the codecs used to compress documents. Codecs used to compress documents must be lossless. If someone sends you a spreadsheet that has been compressed, when it de-compresses the data must be exactly the same as it was before the compression. Codecs such as JPEG, however, are known as lossy codecs, because some of the original information is lost during the compression. The original cannot be recreated from the compressed version of the file. Lossy codecs operate under the assumption that the quality lost either is not noticed by the end user or is an acceptable compromise required for the situation.

Web sites are a perfect example. Having lots of imagery on a Web site is great, but if the images were all 5 MB originals, each page would take forever to load. Because browsing the Internet should be a rapid, seamless experience, and because we sit so close to our monitors, the amount of detail required in a Web site image is much less than what is required for a printed page, so the image can be compressed heavily using the JPEG codec, and our experience isn't overly compromised.

The same holds true for podcasts. While it might be nice to have 256 kbps CD-quality podcasts, the reality is 128 kbps offers more than enough quality, and in fact 64 kbps might be plenty, particularly if you're not using the MP3 codec. As you reduce the bit rate of your podcast, the quality is also reduced, because the codec must delete lots more information.

Codecs try to maintain as much fidelity as possible during the encoding process, but at low bit rates something has to give. There simply isn't enough data to reproduce the original high fidelity. Given the complexity of the task, they actually do an amazing job. They're able to do as well as they do because they make use of perceptual models that help them determine what we perceive as opposed to what we hear. The difference is subtle, but key to modern codec efficiency. Before we talk about perceptual encoding techniques, let's talk a bit about basic codec technologies.

How codecs work
Codecs reduce file sizes by taking advantage of the repeated information in digital files. Lots of information is repeated. For example, a video that has been letterboxed (black stripes on the top and bottom) has lots and lots of black pixels. This results in lots and lots of zeros, all in a row. Instead of storing thousands of zeros, you could store "1000 × 0," which is only six characters. That's a significant savings. Also, you can reconstruct an exact copy of the original based on the information that you have stored.

Another way of encoding is to substitute for commonly occurring combinations of characters. For example, you could make this book smaller by replacing every instance of the word "podcasting" with "p." This wouldn't save that much space, though, and that's the problem with lossless encoding. You can achieve some file size reduction, but typically not enough for our needs. For this, you need perceptual encoding.

Encoding : Throughput & Quality equivalents

2008-08-22T03:20:00.000-07:00

Throughput
As mentioned in the previous section, throughput is the measure of the amount of bandwidth you use over time. You'll encounter throughput when you use a service to distribute your podcast, because most offer a certain amount of throughput for free and bill you for any used in excess of that. Obviously, you want to keep your monthly bill as low as possible, so you want to try to limit the amount of throughput you use.

When you encode your podcast, you want to balance the desire to provide the highest quality possible with the reality of your throughput bill at the end of the month. Many podcast distribution services offer generous amounts of free throughput each month, so this may not be an issue when you first start out. If your podcast becomes wildly popular, though, you may be faced with a need to cut your operating costs (until that first sponsor or advertiser comes around, of course). If so, you may want to consider reducing the bit rate of your podcast, which reduces the quality of your podcast, but that may not be noticeable to your audience. Remember, most people listen to podcasts while sitting in front of their computers, and multimedia speakers aren't renowned for their quality. What you want to deliver is a podcast quality that is equivalent to other broadcast media, which in the case of AM and FM radio isn't that high to begin with.

Quality equivalents
The concept of broadcast quality to mean really, really good. However, anyone who has listened to AM radio knows that it doesn't sound anywhere near as good as FM, and for that matter FM radio doesn't sound as good as CDs. Yet they're both broadcast standards, and we still listen to radio, even AM. Different types of programming do not need as much fidelity as others.

The idea, then, is to figure out how much fidelity your programming requires and produce content to that standard. When recording the content, you should always record at a very high standard, because that gives you the most flexibility later on. But when it comes time to encode your content for Internet distribution, you may want to sacrifice a bit of quality for the cost savings it provides.

Table 1 lists some common bit rates offered by encoding software and brief descriptions of what quality you can expect using different encoding technologies.

Note In Table 1, you should notice that MP3 audio quality is always slightly worse than Windows Media, Real, and QuickTime AAC, particularly at low bit rates. This is because the MP3 codec is older and wasn't really designed for low bit rate encoding. At higher bit rates (128 Kbps and above), the quality differential is less apparent.

Why Encoding Is Necessary - Bandwidth

2008-08-12T03:09:00.000-07:00

You've spent countless hours and quite possibly a sizeable sum of money to produce a broadcast-quality podcast. Now you're being asked to take the polished result and convert it to a different format, which may compromise the quality of the original. Why?

The simple answer is because the raw audio and video files are too large to deliver practically via the Internet. There's no technical reason you can't deliver the original files — but it would take an incredibly long time for the files to download, and your monthly delivery bill would be sky high. To better understand the practical limitations involved, you must understand the concepts of bandwidth and throughput.

Bandwidth
Bandwidth, in the networking sense of the word, is a measurement of the amount of data that is being transmitted at any given point. Throughput is the aggregate amount of bandwidth that has been used over a given time period. Think about water coming out of a faucet: The water can come out slowly or quickly depending on how much you open the tap. A gallon jug fills slowly or quickly depending on how fast the water is coming out. The "bandwidth" of the faucet is the speed of the water coming out; the "throughput" is the total amount of water that comes out.

In podcasting, we come across bandwidth and throughput in a number of different areas. First, each of your potential audience members is connected to the Internet in some way, and that connection has an advertised bandwidth. If they're on DSL or cable modem, they may have a download bandwidth somewhere between 256 kilobits per second (kbps) to several megabits per second (mbps). Similarly, when you upload your podcast to a server or distribution service, you're using bandwidth, but you're uploading, not downloading. The upload or upstream speed of DSL and cable modems is usually far less than the download speed. Regardless of which direction the data is traveling, the bandwidth available determines the speed at which the transfer takes place.

Let's say you've recorded a 20-minute audio podcast. If you've recorded at CD quality, you recorded in stereo, sampling at 44.1kHz, using 16 bits per sample. We can determine how large this file is using some simple math:

44,100 samples/sec * 16 bits/sample * 2 channels = 1,411,200
bits/second
1,411,200 bits/sec / 8 bits/byte = 176,400 bytes/second
176,400 bytes/second / 1024 = 172.3 kilobytes per second (KBps)
172.3 KB/sec * 60 secs/min * 20 min = 206,718.75 KB
206,718.75 / 1024 = Approximately 202 megabytes (MB)

So the raw file is over 200 megabytes. (In fact, you can do this math much more quickly: One minute of stereo CD audio is approximately 10 MB, so 20 * 10 = ∼200 MB.) Let's assume one of your audience members is on a fairly standard DSL line, with a download speed of approximately 500 Kbps. You can calculate the download time with a bit of math. All you have to do is convert the file size from megabytes into kilobits, and then divide by the download speed:

200MB * 8 bits/byte = 1600 megabits
1,600 megabits * 1024 = 1,638,400 kilobits
1,638,400 kilobits / 500 kbps = 3,266 seconds
3,266 seconds / 60 seconds/minute = 54.6 minutes

So your podcast would take just under an hour to download. If the person is downloading in the background, this might not be too much of a problem, but chances are he's checking e-mail, surfing the Web, and doing other things on his computer that might further constrict the available bandwidth, which in turn makes the download take even longer. Additionally, he may not be getting the full bandwidth that he's paying for (see the "Why Does My Broadband Connection Seem Slow?" sidebar). Overall, this is not an optimal experience.

What we want to do is deliver a high-quality podcast that doesn't take hours to download. Encoding software enables us to do precisely this. For example, if we encode the file using an MP3 codec, we can achieve CD quality using only 128 kbps. In this case, our file would be:

128 kbits/sec * 60 seconds/minute * 20 minutes = 153,600 kilobits
153,600 kbits / 8 bits/byte = 19,200 kbytes
19,200 kbytes / 1024 = 18.75 MB

Our file size is less than ten percent of what it was before, and the download time is therefore reduced to about five minutes, which is much more like it. And because each of your listeners is downloading a smaller file, you use much less throughput.

Advanced Video Production Techniques - Adding Titles

2008-08-05T14:58:00.000-07:00

Most professional video programming has some sort of opening sequence that usually includes lots of candid footage mixed with shots of the star(s) and some sort of graphic rendition of the title of the program. You should take the same approach. If your show has a name, let folks know about it! If they download it to their iPod and forget about it until it magically appears on their screen one day when they're browsing through their clips library, you want them to know the name of the program and who you are. So you'll probably want to use titles.

However, the problem is that what looks good (and is legible) on a television screen in general ends up way too small to be read on a small 320×240 screen. Titles at the bottom of the screen (called lower thirds) can be very hard to read if they're not done with large enough fonts. PowerPoint slides are particularly tough, because most people try to pack far too much information into a single slide, which makes it difficult for people to absorb, and the small fonts become very hard to read when reduced. To top it all off, video codecs have a tough time with text, because they don't treat it as being distinct from the video. So when your podcast is encoded, you're going to lose even more quality, as depicted in Figure 10.9.

Figure 1: PowerPoint slides are a good example of why text is tough: (a) Scaled to 320×240 and (b) after encoding at 300 Kbps.

The PowerPoint slide in Figure 1 isn't too bad to start off with; it has only five main points on the slide. By the time the slide is reduced to 320×240, the sub-points are too hard to read, and after the encoding process, even the main points are starting to look a little ragged.

If you're going to use text in your podcast, think big. Try not to have more than three or four points per slide if you're using PowerPoint, and if you're adding titles to your show and/or your guests, make sure to use a font large enough so that it is legible after the encoding process.

Advanced Video Production Techniques : Inserting Virtual Backgrounds Using Chroma Key

2008-07-30T02:54:00.000-07:00

If you've ever wondered how your local weatherman manages to stand in front of huge swirling weather maps, the answer is using a technology known as chroma key (also called green screen or blue screen). The weatherman isn't actually standing in front of those pictures. He's standing in front of a blank wall painted a very bright, unnatural green. Then, using what until recently was incredibly expensive technology, the green background is removed from the video image and replaced with the graphics that you see on television. When the weatherman is looking off to the side, he's actually looking at a small television monitor to figure out where to point.

Nowadays, chroma key is built into many video-editing platforms. Some require an additional plugin, but others include it as part of the basic functionality. To use this feature, however, you have to film yourself (or whoever your subject is) in front of a green (or bright blue) wall. The trick is to make sure the wall color is very uniform and is lit in such a way that there are no shadows on the wall. You can buy custom paint that the professionals use to paint their chroma key walls, or if you're budget constrained, you can buy a roll of bright green butcher paper at your local art supply store.

You need a large area to film against, because you have to stand far enough away from the green screen so that you don't cast any shadows on it. Lighting for a green screen shoot is an art form in itself. This is a good example of where calling in a professional to help you out is a great idea. After you've got a lighting setup established, you can reuse it for future shoots.

After you've shot your video against the green screen, the process for substituting the background depends on your video-editing software. Figure 1 illustrates the chroma key effect from Vegas. After you've specified what color to use as the key for the chroma key effect, that color is removed from the frame and another image or video is substituted where the key was.

Figure 1: Vegas chroma key effect

Tip One good reason to use chroma key is that the backgrounds are generally static, and as we'll find out later, static backgrounds encode best. Conversely, don't use backgrounds with motion in them if they can be avoided.

Most video-editing programs deal with video in terms of tracks, so when the chroma key effect is used, the video track beneath the main track is revealed. This is how the weatherman appears to be standing in front of the weather maps. In actuality, the weather maps are just showing through where the original chroma key color was.

Cropping and Resizing

2008-07-18T13:30:00.000-07:00

At some point, you may want to cut out part of your video image. For example, the original video may not have been framed well, and you may want a tighter shot. Or there may be something objectionable in the shot that you want to remove. Cutting out this unwanted video is called cropping. If you're targeting video iPods, you also have to resize your video to 320×240, which is the resolution of the iPod video screen. Video-editing platforms allow you to do this, but in order to do it correctly without introducing any visual distortion, you must understand what an aspect ratio is.

Aspect ratios
The aspect ratio is the ratio of the width to the height of a video image. Standard definition television has an aspect ratio of 4:3 (or 1.33:1). High definition TV has an aspect ratio of 16:9 (1.78:1). You've no doubt noticed that all the new HDTV-compatible screens are wider than standard TVs. When you're cropping and resizing video, it's critical to maintain your aspect ratio; otherwise, you'll stretch the video in one direction or another.

To better understand this, let's look at how NTSC video is digitized. The original signal is displayed on 486 lines. Each one of these lines, or rasters, is a "stripe" of continuous video information. When it is digitized, it is divided up into 720 discrete slices, each one of these slices is assigned a value, and the values are stored digitally.

However, when you display the digitized 720×486 video on a computer monitor, the video appears slightly wider than on a television, or looked at another way, the video seems a bit squished. People look a little shorter and stickier than usual, which in general is not a good thing. Why is this?

If you do the math, 720×486 is not a 4:3 aspect ratio. If you could zoom in and look really closely at the tiny slices of NTSC video that were digitized, they would be slightly taller than they are wide. But computer monitor pixels are square. So when 720×486 video is displayed on a computer monitor, it appears stretched horizontally. To make the video look right, you must resize the video to a 4:3 aspect ratio such as 640×480 or 320×240. This restores the original aspect ratio, and the image looks right.

Note Those of you paying attention may be wondering about standard definition television displayed on the new widescreen models. The simple answer is that most widescreen TVs stretch standard television out to fill the entire 16:9 screen, introducing ridiculous amounts of distortion. Why that is considered an improvement is anyone's guess.

With the availability of HDV cameras, some of you may be fortunate enough to be working in HDV, which offers a native widescreen format. If so, you'll be working with a 16:9 aspect ratio such as 1080×720 or 1920×1080. Regardless of the format you're working in, the key is to maintain your aspect ratio.

Cropping
If you decide you need to do some cropping, the key is to crop a little off each side to maintain your aspect ratio (see Figure 1). Some video-editing platforms offer to maintain the aspect ratio automatically when you're performing a crop, which is very handy. However, many of the encoding tools require that you manually specify the number of pixels you want shaved from the top, bottom, right, and left of your screen. If that's the case, then you have to do the math yourself and be sure to crop the right amounts from each side.

Figure 1: Be careful with your aspect ratio when you crop.

As an example, let's say that you needed to shave off the bottom edge of your video. You could estimate that you wanted to crop off the bottom 5 percent of your screen, which would mean 24 lines of video. Assuming you were working with broadcast video, to maintain your aspect ratio, you'd need to crop a total of:

24 * 720 / 486 = 35.5 or 36 pixels

So you'd need to cut 36 pixels off the width to maintain your aspect ratio. You could do this by taking 18 pixels off either side, or 36 pixels off one side. It doesn't matter; where you crop is dependent on what is in your video frame. Of course, this is assuming that you're working with NTSC video. The math varies slightly if you've already resized the video to a 4:3 aspect ratio such as 640×480.

One thing to bear in mind is that some codecs have limitations on the dimensions they can encode. Codecs divide the video frame into small boxes known as macroblocks. In some cases, the smallest macroblock allowed is 16×16 pixels, which means that your video dimensions must be divisible by 16. Most modern codecs allow macroblocks to be 8×8 pixels, or even 4×4 pixels. The great thing about 320×240 is that it works for even the largest macroblocks.

Resizing
Resizing is pretty easy; just make sure you're resizing to the correct aspect ratio.

Video Signal Processing : Using deinterlacing filters

2008-07-08T12:05:00.000-07:00

You should have an understanding about why you'd want to do some video signal processing. Even if you've done a great job producing and capturing your video, there are still fundamental differences between television and computer monitor displays that should be compensated for. To do this, you need to de-interlace your video and adjust your color for RGB monitors.

Using de-interlacing filters
Most editing platforms have de-interlacing filters built into them. As we saw in Figure 10.1, the problem is dealing with the artifacts that arise when two fields of interlaced video are combined to make a single frame of progressive video. Three methods are commonly used to deal with interlaced video:

Blending: This approach combines the two fields, but it's vulnerable to interlacing artifacts, as shown in Figure 10.1.

Interpolation: This approach attempts to shift parts of one field left or right to compensate for the artifacts. This is very computationally complex, because only parts of the field should be interpolated. For example, in Figure 10.1, we want to interpolate the parts of the frame that include the moving minivan, but not those that contain static elements such as the trees in the background.

Discarding: This approach discards one field and uses a single field twice in a single frame of progressive video. The resulting frame therefore has half the vertical resolution of the original frame, but without the interlacing artifacts.

Editing and encoding platforms distinguish themselves by how they deal with interlacing artifacts. De-interlacing video on two different platforms generally yields different quality results. Where you choose to do your de-interlacing depends on where you can get the best quality. If you're staying in the broadcast world for your editing phase, it makes more sense to de-interlace during the encoding phase. This is demonstrated for you in the next section.

However, we have to come clean about de-interlacing. For the most part, it isn't necessary for most podcasts. If you're encoding your podcasts for viewing on a video iPod (or other portable media device), chances are good that you're targeting a resolution of 320×240. At this resolution, most encoding software drops the second field by default! If you've got only 320 lines of resolution, it doesn't make sense to process the second field, so you don't have any interlacing artifacts to deal with. This is a very good reason to target 320×240 for your podcasts: The de-interlacing problem goes away.

If, however, you're targeting browser-based playback for your podcast and decide to use a resolution larger than 320×240 — such as 400×300, 480×360, or 640×480 — you need to de-interlace your video during the encoding phase. So, for you mavericks, the next section shows where to find the de-interlacing filter in a number of software applications.

Where to find de-interlacing filters
If you're hoping to de-interlace your video (assuming that your final video podcast resolution is larger than 320×240), you need to make sure your encoding application has de-interlacing filters. Most, but not all, do. If you're targeting the QuickTime format, use an encoding application such as Sorenson Squeeze, because QuickTime Pro doesn't include a de-interlacing filter.

Sorenson Squeeze includes a de-interlacing filter in the filter settings window, shown in Figure 1. Double-click any filter to open the filter settings window. The de-interlacing filter is on by default in the preset filters.

Figure 1: Sorenson Squeeze offers de-interlacing in the filter settings window.

If you're targeting the Windows Media Format, you can use the de-interlacing filter included in the Windows Media Encoder. The de-interlacing filter is on the Processing tab of the Session Properties window, shown in Figure 2.

Figure 2: The Windows Media Encoder offers a de-interlacing filter in the processing settings.

If your encoding application doesn't have a de-interlacing filter, chances are good that your editing platform will. Vegas includes the de-interlace setting in the Project Properties window, shown in Figure 3. Select Project Properties from the File menu or type Alt+Enter, and then select the deinterlacing method you want from the drop-down menu.

Figure 3: Vegas offers a de-interlacing filter in the project properties window.

Display Technology Differences

2008-07-05T11:59:00.000-07:00

Television screens display images using a completely different technology than computer monitors. This is unfortunate because it leads to problems when trying to display video on a computer screen. However, it also can be a blessing, because television technology is nearly 100 years old, and much better technology is now available. The problem is that for the foreseeable future, we're caught between the two, shooting with cameras that are designed to record video in the NTSC/PAL (television) standard, and distributing our video on the Internet to be viewed on modern displays.

Interlaced versus progressive displays
Each frame of video is divided into two fields, one consisting of the odd lines of the image and the other the even lines. These two fields are scanned and displayed in series. So television actually is 60 fields per second, which we see as continual motion.

Computer monitors, whether they're cathode ray tube (CRT) or liquid crystal display (LCD), are progressive monitors. Each frame of video is drawn from left to right, top to bottom. There are no fields. The problems appear when we try to create a single frame of progressive video from two fields of interlaced video (see Figure 1).

Figure 1: Converting two fields of interlaced video with significant horizontal motion to a single frame of progressive video can be problematic.

In Figure 1, a minivan is driving past the camera. During the split second between the first and second field scans, the minivan has moved across the frame. When this video is displayed on an interlaced display, it appears normal, because the second field is displayed a split second after the first. However, if we try to combine these two fields of interlaced video into a single progressive frame, interlacing artifacts appear because of the horizontal motion. The front edge of the minivan is "feathered," and both tires are a blur. At either the editing or the encoding phase, something must be done to deal with this problem.

Color spaces
Television and computer monitors encode color information differently. Television signals are encoded in terms of luminance and chrominance (YUV encoding); computer monitor signals are encoded in terms of the amount of red, blue, and green in each pixel (RGB encoding). We also watch them in different environments. Televisions are generally viewed in somewhat dim surroundings, whereas computer monitors are generally in bright areas. The combination of these factors means that content created for one environment doesn't look right when displayed on the other.

Digitized NTSC video looks dull and washed out when displayed on a computer monitor. Video that has been processed to look right on a computer monitor looks too bright and saturated (colorful) when displayed on an NTSC monitor. The non-compatibility between the two display technologies makes it problematic to create high-quality video, particularly if you want to display your content on both. If you're producing content for both broadcast and the Internet, at some point your project must split into two separate projects. After you start processing a video signal for display on a computer monitor, you won't be able to display it on a TV monitor.

Tip The best way to manage this issue is to work exclusively in the broadcast space during your digitizing and editing phases. Archive your masters in a broadcast format. Don't do your post-processing for Internet viewing until the encoding phase, or at least after all your editing has been done and you have a broadcast-quality master. That way, you always have a version of your video that can be broadcast or burned to DVD. Create a special version that is intended for Internet-only consumption. As new formats evolve, you can always re-encode from your broadcast-quality master.

Advanced Video Production Techniques

2008-07-02T11:57:00.000-07:00

So you've figured out how to shoot some video and managed to load it into your computer. It looks good, but something's not quite right. The video just isn't quite as bright and colorful as you remember. That's because there are fundamental differences between televisions and computer monitors.

Before we dive into the technical minutiae of display technologies, let's talk briefly about some simple tools you can use to improve your video image before it hits tape. Lens filters can be a very cost-effective way of improving your video quality.

Understanding Lens Filters

Many of you may have at one time or another played around with photography. If you ever progressed beyond "point-and-shoot" cameras, one of the first accessories you probably purchased was an ultraviolet (UV) filter for your lens. UV filters are useful because they prevent UV light from entering your lens, which can make your pictures look slightly blurry, and because they protect your lens. Mistakenly scratching a $25 filter is far preferable to scratching a fancy zoom lens that cost you hundreds of dollars.

The same applies for your DV camera. Protecting your investment by buying a cheap and replaceable filter is a good idea, and as with photography, filtering out UV light gives you a cleaner video image. If you're wondering how a UV filter works, chances are good that you've experienced it many times. Every time you put on a pair of sunglasses, you're filtering out UV light (among other things). The immediate effect is a clearer, crisper image. Even though we can't see UV light, it interferes with our ability to perceive visible light. DV cameras have the same problem, so a UV filter is always a good idea.

A number of other lens filters can be used to improve the quality of your podcast. The next few sections discuss them generally. To learn more about exactly which filter you should use with your model of camera, you should consult online discussion boards and digital video camera review sites.

Diffusion
Diffusion filters soften your video image. We've all seen diffusion at work in the movies, particularly in the film noir genre. The camera cuts to a shot of the gorgeous female actress, and she's practically luminous. This is achieved using a fairly heavy diffusion filter. Although this would be overkill for most podcasting applications, using a light diffusion filter gives your podcast a distinctive look. It also can help your encoding quality.

Many DV cameras default to shooting a very high contrast image, and some even use special processing to exaggerate the edges between objects. This can be okay in situations where there isn't much contrast to begin with, but if your scene is lit properly, you should have plenty of contrast. Video that has too much contrast looks amateurish. Using a diffusion filter can mitigate this by softening the entire image ever so slightly. Diffusion filters can make your podcast look more "filmlike," which is generally desirable.

Video with too much contrast also is more difficult to encode, because it has lots of extra detail in the frame. This makes the encoder's job harder, because it tries to maintain as much detail as possible. Using a diffusion filter helps soften the image slightly, which reduces the amount of detail, thereby making the image easier to encode.

Color correction
The UV filter described at the beginning of this section is essentially a color filter, designed to filter out colors beyond our range of vision. There are many more color filters that you can buy for other situations. One of the most useful for many podcasters is the fluorescent light filter. Fluorescent lights emit a very particular type of light, with a lot of extra green in it. Because of the large amount of green content, fluorescent lights tend to make people look slightly ill. Using a fluorescent filter when filming in offices or other fluorescent lighting situations can make your podcasts look warmer and more natural.

You also can buy filters that are designed to enhance certain parts of the color spectrum. These are fairly specialized and not for the average podcast producer. If you're looking for a special effect, you're probably better off trying things out in your video-editing platform, where you can safely undo those mistakes.

Polarization
Polarization filters are used to filter out reflected light. For example, filming through a window can be very difficult because of the reflections. Using a polarization filter removes this reflected light and allows you to film what's on the other side of the glass. Similarly, if you're trying to film under water, for example fish in a pond, you need a polarization filter. Polarization is often used in sunglasses for this reason.

Archiving Your Podcast

2008-06-28T11:56:00.000-07:00

As you probably are beginning to realize, quite a bit of work goes into creating a video podcast. If you've got a FireWire setup, it can be pretty simple, but if you're using a video capture card and an analog camera, you may have to fiddle with your settings. Depending on how much editing you do (and how many cutaways you have to use), your final master may be quite a bit different from what you originally started off with. It's very important, therefore, that you archive your work so that you don't have to start from scratch if you decide to re-edit your podcast, perhaps for a "bestof" end-of-year show.

For that matter, your podcast may not be the only outlet for your programming. You may decide you want to put out a DVD or license your programming to a cable channel. The possibilities are all out there, but if all you keep lying around are the low-bit-rate podcast versions, you'd have to do lots of work to recreate your masters.

Save your work in as high a quality as you can. If you're working with a FireWire system, you can usually print your master right back to a DV tape. You can obviously keep a DV version on your hard drive if you've got space, but video files can fill up a hard drive quickly. DV tapes are compact and a fairly reliable backup method.

If you're not working with a FireWire system, or if you just want to keep pure digital copies lying around, consider buying an external hard drive (or two). You can use one to do all your capturing and editing and keep the other for archival purposes. Without the luxury of FireWire, you won't be able to save to DV, because video capture cards don't work in reverse; you can't print your edited master back to tape. You have to rely on digital storage.

One thing that hasn't been thoroughly established is how long hard drives will last. It's fairly common knowledge that hard drives in servers that are working 24 hours in a day have an average life expectancy of about three years. However, they're usually higher quality drives than most people have in their laptops or home desktop systems. Much like light bulbs, it's the turning on and turning off that are hardest on the drive.

If you're using external drives, you may not be using them every day, which in theory extends their life cycle, but if you put them on a shelf and forget about them, had drives have been known to "freeze." The data on the disc platters is intact, but the hard drive is unable to spin the platters to access the data. You can send drives in this condition to companies that specialize in data rescue, but the process is very expensive.

Unfortunately, we have no good answer as to how long hard drives are going to last. Institutions such as banks that rely on data use tape backup systems to maintain their data integrity. A number of pro-sumer tape backup formats are available nowadays. They're not cheap, but if you want a guarantee that your programs will be available 5, 10, or 25 years from now, you should consider investing in a good tape backup system, or open up an account with a backup company.

Tips : Editing Your Podcast

2008-06-24T11:51:00.000-07:00

After you've transferred your video to your computer, you need to tidy up the rough edges of your video production and turn your podcast into a masterpiece. Well, we can hope, can't we? You should edit with an eye on three things: content, quality, and convenience.

First and foremost, you want your podcast to have good content from start to finish. If you are interviewing a guest for your podcast, you probably had a long list of questions to ask. When you're reviewing your footage, try to keep your distance from the material, and only keep what works best. Of course, some guests may be fantastic, and you'll want to keep every syllable they utter. Often, however, you'll find that a few questions just didn't go anywhere or didn't reveal anything new (see the "Ask the Right Questions" side bar). If so, edit it out. With a few nimble edits, the pacing of a show can change dramatically, turning a mediocre show into a great show.

Keep edits short and sharp
When you're editing, most edit platforms offer a number of transition options for you to choose from. In general, anything other than a quick cross fade (also known as a dissolve) should be avoided, for a couple of key reasons. First, if you watch closely, crazy transitions are almost never used on television or in film. Over-the-top transitions detract from the story line and call way too much attention to themselves. For this reason, they're a dead giveaway that an amateur is at the controls. Second, there's a technological reason why you shouldn't use complicated transitions. They are incredibly difficult to encode. If you're encoding for a broadband audience, the bit rates you use simply aren't capable of encoding that much motion efficiently. You'll either end up with a transition that looks like mud, or you'll be forced to encode your podcast at a higher bit rate, which means a larger file, a longer download for your audience, and a bigger bandwidth bill at the end of the month.

Cutaways
Cutaways are small pieces of film that you can use when editing video, often used to cover up an edit. Editing video can be tricky because people can see when and where you edit your video. You can't just cut out the middle of an interview without some clever editing, or people will notice that there's something missing. This is where cutaways can really help.

Imagine an interview on a conference floor, where someone rudely interrupts your guest while she's answering a question. Unless the interruption was by someone important (or it was really funny), you probably want to edit it out of the podcast. If you just cut it out, there will be a sudden jump in the video (known as a "jump cut" in the industry). You have to disguise your cut using a cutaway.

Here's how it works: When the interruption occurs, cut to some b-roll, like a shot of you nodding in agreement or a shot of the conference room floor. Let the audio of your guest's response continue to play underneath the b-roll. Then, you can cut from the b-roll with the guest audio underneath it to an appropriate location after the interruption occurred. The jump cut will be hidden by the b-roll, and your secret will be safe. This editing approach is illustrated in Figure 1.

Figure 1: Use cutaways to disguise your edits.

Tip Provided you have plenty of cutaway material, it's often easiest to edit your story together by editing to your audio and then covering any awkward transitions with cutaway or B-roll material.

Video capture cards

2008-06-20T16:42:00.000-07:00

If you have no way to utilize FireWire, you have to use a video capture card to convert the analog video signal into digital information. Video capture cards, like cameras, are available at a wide range of price points. The more you spend, the higher quality your video capture will be.

Video capture card settings
Using a video capture card involves connecting your camera to the capture card and then specifying the settings for your capture. Where and what settings you can specify depends on your capture card and your video-editing platform. Essentially, you specify the following:

Resolution: The dimensions of your screen capture

Frame rate: How many frames per second to capture

Data rate (or compression): Whether to capture the video uncompressed or use a codec during capture

You also may be able to adjust the video settings for your capture, such as brightness, contrast, and saturation. However, the adjustments offered by most budget capture cards tend to be fairly coarse. A better approach is to digitize your video as purely as possible and to do your adjustments using video-editing software, which enables a much finer degree of control — and the ability to "undo."

To capture the highest quality video possible, try to capture full screen, full frame rate, and uncompressed. You may have to scale back, however, depending on your hardware situation. Full-screen uncompressed capture is a very data intensive process, requiring a fast machine and lots of storage. If you have to scale back, start by trying to use a different encoding scheme such as YUV. If your machine still can't capture full frames reliably, you'll have to reduce your resolution, possibly to 1/2 size (320×240). This is a perfectly acceptable starting point for a video podcast, provided you can capture at full frame rate.

Digitizing via a capture card using SwiftCap: A step-by-step example
If you are capturing video via a capture card, you can choose some settings. Most video-editing platforms come with a video capture application that allows you to access your video capture card and adjust your settings. In this example, we'll use SwiftCap, which is the video capture application that comes with all cards sold by Viewcast, one of the more popular video capture card manufacturers. It has some nifty features that you'll find handy for successful video captures.

Follow these steps to digitize video with SwiftCap:

1. Make sure that your capture card is installed correctly and that your camera or videotape deck is connected to your capture card.

2. Open SwiftCap. Provided your camera is running, you should see a preview of your video (see Figure 1). If you don't see a video preview, make sure "Preview Video" is checked on the View menu.

Figure 2: The ViewCast SwiftCap application

3. If you're still not seeing video, make sure your video source is correct. Many video capture cards have multiple inputs, for example, a composite input and an S-Video input. To check your source setting, choose "Capture Settings" from the Settings menu or click the capture settings icon (see Figure 2).

4. Select the appropriate source from the drop-down Source menu on the left side of the Capture Settings window (see Figure 3).

Figure 3: Select the appropriate source in the Capture Settings window to make the preview active.

5. Before you do any capturing, make sure your system is capable of capturing the screen resolution and encoding scheme you want to use. Ideally, you want to capture full screen (720×486, or 640×480 if your capture card automatically scales the input), but this requires a fast computer and plenty of storage. SwiftCap includes a handy disk performance analyzer that can save you lots of woe. From the Tools menu, choose "Disk Performance." This brings up the Disk Analyzer shown in Figure 4.

Figure 4: Click "Profile Drive" in the Disk Analyzer window to analyze your hard drive performance.

6. Select the drive you intend to capture to in the Local Drives pane, and click the "Profile Drive" button. The analyzer then determines the speed at which you can capture video and displays the results in the lower right. You can see in Figure 4 that this drive is capable of capturing only 20.8 frames per second using RGB 32 encoding. We'll have to choose a different encoding scheme to get the full frame rate.

Tip You should always capture video to a drive other than the system drive if possible.

7. The idea is that you have to get your frame rate comfortably over 30 frames per second. YUV encoding is more efficient, so you can usually get your frame rate up considerably by switching to a YUV encoding scheme. In Figure 5, you can see that switching to YUY2 puts our potential frame rate over 40, which is far more than we need.

Figure 5: Using a YUV encoding scheme is more efficient and allows higher frame rate captures.

8. After you've found settings that work with your system, go back to the Capture Settings window and enter those settings (see Figure 6).

Figure 6: Be sure to choose the right settings in the Capture Settings window.

9. Next, specify which drive you want the captured file saved to. Select "Capture Destination" from the Settings menu, or click the capture settings icon to bring up the Capture Destination window (see Figure 7). Clicking the double arrow button at the top right opens a browse window where you can specify a location and a filename. Be sure to use the same drive that you tested in Step 5.

Figure 7: Specify where to put your captured video file.

10. You should now be ready to capture video. Rewind the tape to just before where you want to start capturing, start tape playback, and then start the capture process by selecting "Start" from the Capture menu or by clicking the start capture icon.

11. SwiftCap disables the video preview during capture, so you have to either monitor via your camera's monitor or an external monitor. When you've captured what you needed, choose "Stop" from the capture menu or click the stop capture icon.

12. After you stop your capture, SwiftCap displays a capture results window. It is critical that your capture have zero dropped frames. If your capture dropped frames, you should recapture your video using a different encoding scheme or a smaller capture resolution.

That should be it. Using a capture card requires a few more steps than using a FireWire setup, but you should be able to get equally good quality, provided you're using a good quality capture card.

FireWire & setting it

2008-06-17T20:35:00.000-07:00

By far the easiest method of capturing video is via FireWire. FireWire (officially known as IEEE 1394, and also known as iLink) is a standard by which data can be exchanged at very high speeds using a special cable and a FireWire port. Most digital video (DV) format cameras include a FireWire port. In addition to data transfer, the FireWire standard includes the ability to control remote devices (such as a camera). This makes capturing video from your DV camera a snap.

Simply connect the camera to your FireWire port, and open your video-editing platform. Most video-editing platforms include some sort of built-in "import" or "capture" functionality. You can generally control the camera from within the application and specify what part of the tape you want to capture. If you want to capture the whole tape, just rewind and hit the capture button.

If your computer doesn't have a FireWire port built in, you can buy a FireWire card for less than $50. If your camera doesn't have FireWire built in, you can buy a digital video converter. Digital video converters take analog audio and video inputs, for example from your camera, and create a DV signal that is available on the FireWire port. An added benefit of digital video converters is that they work both ways, meaning you can send the output of your video editor to the FireWire port, and the digital video converter converts it back to an analog signal that can be displayed on a monitor for quality-assurance purposes.

FireWire settings
One of the advantages (some might say disadvantages) of digitizing via FireWire is that there really are no settings for you to adjust. The DV standard is hard-coded into the entire process. You'll always be capturing full screen, full frame rate, using the DV codec.

The DV codec is another advantage to capturing via FireWire. Digital Video (DV) is compressed as it is recorded, making DV files about 1/5 the size of uncompressed video files. This makes them easier to store and move around. The compression affects image quality, however, and is one of the reasons that DV isn't considered true broadcast quality. However, the ease of use and the price points of DV cameras are virtually impossible to argue with.

Capturing via FireWire isn't really capturing in the truest sense; it's really just transferring the file from your camera (or tape deck) to your computer, just like you'd transfer a file from one computer to another. Because it's just a file transfer process, the video on your computer is an exact copy of the information on your camera.

Transferring files via FireWire using iMovie: A step-by-step example
Like so many things in the MacOS world, transferring DV from your camera to your Mac is a snap. Follow these steps:

1. First, connect your camera to your Mac's FireWire port, and turn your camera on to the playback or VCR position.

2. Open iMovie.

3. iMovie automatically detects that you have a camera connected and opens in "camera mode" (see Figure 1).

Figure 1: iMovie automatically detects a camera connected to your Mac and opens in camera mode.

Tip In camera mode, the stop, play, fast forward, and rewind buttons control your camera. You can use these controls to find the portion of your tape that you want to import.

4. To begin the import process, click the Import button (or hit the spacebar). If the tape is already playing, iMovie starts importing video from that point. If the tape is stopped, iMovie starts tape playback and begins importing.

5. iMovie automatically breaks up the imported video into clips each time it senses a new scene. This can be very handy, but it also can be a problem if you're trying to import a pre-edited piece of video with multiple scenes. You can disable this feature. From the iMovie menu, select Preferences (or just hold down the Apple button and push the comma key). Select the Import tab, and then deselect the "Start a new clip at each scene break" option.

That's it! You can now drag your clips to your iMovie timeline and edit away.

Digital video : Podcasting

2008-06-15T20:10:00.000-07:00

To convert analog video into a digital format, the process is similar to digitizing audio. The incoming analog signal is sampled at discrete intervals, and the values are stored. Each sample is called a picture element, or pixel. To faithfully represent all the information in the video signal, it was determined that each line would be sampled 720 times. Combine this with the 480 visible lines, and you end up with a screen resolution of 720×480.

When we're digitizing video, we're storing values for each and every one of the pixels, of which there are quite a few:

720 * 480 = 345,600 pixels

Multiply that by 30 frames per second, and we're looking at over ten million values that have to be stored every second. For each one of these values, we have to allot a certain number of bits to store the value. Even if we try to limit the number of bits we use to store each value, we'll still end up with a very large file. We'll find later that this becomes even more of an issue when we're encoding for a podcast. In order to send files over the Internet, we must reduce them to a manageable size, and doing so with video requires some compromises.

One of the main compromises that can be made is the encoding scheme used to assign values to each pixel. You can assign this value in a number of different ways. Because all colors can be made out of red, green, and blue, one approach measures how much of each color is present in a pixel and then assigns a value accordingly. This is known as RGB encoding, which is the default method used on computer monitors. Different types of RGB encoding are named according to how many bits are used for the value, such as RGB 24 and RGB 32. RGB encoding can be very high quality, but it isn't the most efficient way to encode video information.

We learned that our eyes perceive light as being composed of luminance (brightness) and chrominance (color content). Our eyes are very sensitive to brightness and not so sensitive to color. Encoding luminance and chrominance information is a much more efficient way of encoding, because the color information can be compressed, and we won't notice the difference. We can get the same video quality, but with a lower data rate. Table 1 illustrates the bit rates and files sizes of some common video encoding schemes.

When digitizing, the best approach is to capture at the highest possibly quality. Starting with the highest possible quality gives you more flexibility during the editing phase and provides better raw material for your video podcast. However, the quality of your video capture may be limited by your equipment. If you're working with the DV format, it is encoded using the YUV encoding scheme and compressed at a 5:1 ratio. If you're trying to capture uncompressed video at full resolution (640×480 or above) you must have very fast hard drives and plenty of storage. Aim for the highest possible quality, and settle for whatever works within your limitations.

How video works

2008-06-12T20:04:00.000-07:00

Many years ago, some clever folks discovered that they could exploit something known as persistence of vision to create the illusion of moving pictures ("movies"). When a series of still images is projected at a fast-enough rate, the human brain "fills in the blanks" and perceives the result as continuous motion. The threshold is approximately 20 frames per second. Anything faster appears to be continuous, and anything slower is perceived as discrete frames (or at least jerky motion).

Fast forward a few decades, and along comes television, which used the same theory, but instead of projecting light through film, television frames were electronic signals that could be broadcast long distances. To create a frame of video, the image is divided into horizontal lines, and each line is scanned inside a video camera and converted into an electronic signal. This electronic signal is broadcast and received by a television, which takes the electronic signal and shoots it at the television screen, line by line.

Of course, all this scanning and projecting happens very quickly. We need to view at least 20 frames per second to see continuous motion. With television, they had to choose a higher frame rate because the frames were drawn line by line, which took some time. Thirty frames per second was chosen as the standard, which was exactly half 60 cycles per second, the oscillating frequency of AC current in the United States.

But there was a problem. Early television technology was limited, and it was discovered that 30 frames per second appeared to flicker every so slightly. The obvious solution was to increase the frame rate, but technology at the time just couldn't handle a higher frame (and hence data) rate. Some sort of compromise had to be reached. The solution was interlacing.

Instead of sending 30 discrete frames per second, each frame of video is divided into two fields, one consisting of the odd numbered lines, the other of the even numbered lines. The fields are scanned alternately, odds and then evens, broadcast, and then projected onto the television screen (see Figure 1).

Figure 1: This figure shows how interlacing works.

Each frame of video contains two fields, which are broadcast at 60 fields per second. Because each field contains exactly half the data of the original frame, the data rate or bandwidth of the signal was the same as the original 30 frames per second non-interlaced signal. Interlacing solved the flicker problem, and thus a standard was born. The National Television Standards Committee (NTSC) standard was for 30 frames of interlaced video per second, divided into 525 lines of resolution, of which approximately 480 lines of resolution are visible. The remaining lines are known as the vertical blanking interval (VBI) and are used for synchronization (and later closed captions).

We'll see later that interlacing is no longer necessary using modern display technology. Computer monitors are not interlaced; they're known as progressive scan devices. For those of you interested in high definition television, this is why there are a plethora of standards in the HD world, both interlaced and progressive. Converting between the two display methods can create problems that we'll have to deal with later.

Recording for podcasting

2008-06-09T20:01:00.000-07:00

If you've gotten this far, we hope you've invested some time and effort in lighting and composing your subject properly, and have your camera on a tripod, white-balanced and ready to go. Action! At long last, the camera is rolling. Or is it? Much like audio-only podcasts, you need to make sure everything is ready to go before you start recording.

What you never hear in the movies is the responses to the director as she yells out "Lights … camera …" When the director yells "lights," the director waits until she hears "lights ready" from the lighting director. After "camera," the director waits to hear "speed," which means that the camera is running. ("Speed" is a throwback to the days when it took a second or two for the camera to get up to speed.) If any extras or special effects need to be cranked up, they'll be cued before the director finally yells "and … action!"

You don't have to yell out loud, but you should develop a mental checklist that you run through every time you're about to start shooting video. Check to make sure all that your lights are on and that they haven't been bumped. Check all your audio equipment to make sure it's ready to go. Finally, press the record button on your camera, and give it a few seconds before you start your podcast production.

After the tape is running, take a deep breath, smile at the camera, and off you go. When you're finished taping, you may want to take a moment to make sure you've got enough footage for your podcast. You may want to shoot some extra footage, such as a special intro or outro, or some b-roll for safety's sake.

Intros and Outros
If you're having guests on your podcast, you may want to consider doing the intro and outro separately. In fact, you may have to record these separately if you've only got one camera and are recording the podcast interview-style (see the "Filming an Interview with a Single Camera" sidebar). It all depends on the type of podcast you're trying to put together and the level of professionalism you want to achieve.

B-roll
It's always a good idea when you're filming to film some extra content to use as b-roll. B-roll is footage that isn't part of the main story but can be inserted into your production from time to time for color or to cover tricky edits. For example, if you're doing a podcast on the latest gadgets at a conference, you should film plenty of b-roll of people demonstrating their gadgets, people milling around popular booths, people laughing, and anything else that helps convey the vibe of the event. You never know when this kind of material will come in handy.

Room tone
Video professionals always record some room tone either just before or after the taping session begins (usually at the end). They do this because sometimes a line or question has to be rerecorded, or overdubbed. For example, a question from the interviewer might be unintelligible or night need to be rephrased. It may be impossible, or too expensive, to re-tape the interview. Instead, you can cheat by overdubbing the question.

The overdubbing session generally takes place at a recording studio, not where the original footage was taped. When the overdubbed question replaces the original question, it is immediately noticeable because you can't hear the room tone of the original interview space. To compensate for this, you can mix in a little room tone, and your overdubbed question will sound as if it was asked during the original taping session.

Taping room tone is easy. Someone, usually the audio engineer, tells everyone to be quiet, and the cameras (and/or audio recording devices) record about 30 seconds of room tone. That's usually more than enough for later use. Be sure everyone who was in the room during the interview stays where they are, because if there are fewer (or more) people in the room when you record your room tone, it will sound slightly different from the room tone during the taping.

White balancing: A step-by-step example

2008-06-06T18:13:00.000-07:00

White balancing: A step-by-step example
You need a decent-sized piece of white cardboard to perform white balancing. Follow these steps:

1. Have your talent hold the white cardboard directly in front of her, where all the lights are focused. If it's a tight shot, she may have to hold it in front of her face.

2. Zoom in until the white card fills the entire shot.

3. Find your camera's white balance control, set it to manual, and then set the white balance. Most cameras have a button to push or a menu option to select.

4. Zoom back out, and behold your wonderfully balanced picture.

When your lighting situation changes, you should rebalance the camera. This is particularly important if you're combining footage shot outdoors with footage shot indoors. If your white balance is off, people's flesh tones shift slightly, as do the colors of their clothing (if they're wearing the same color). If you're unsure whether you should white balance, do it just to be sure.

White-balancing tricks
You can use non-white cards when white balancing your camera for a special effect. Non-white balancing cards come in two flavors: warm cards and cool cards. The process is exactly the same as detailed previously, but by using a non-white card to white balance, you can trick the camera into thinking white is something different, and the result is slightly skewed colors in your video.

Why would you want to do this? Well, warm cards have a slightly blue tint, and when the camera compensates for this, the result is a slightly warmer image. This may be appropriate for a very intimate podcast shot indoors, if you want to make the viewer feel cozy. Cool cards have a slightly orange tint, so the resulting image is slightly blue. You've seen the effect in car commercials or computer commercials, where you get a very cool, impersonal look. This may be appropriate for a technology video podcast.

The best way to find out what warm and cool cards do is to play around with them. If you don't want to shell out the money for the professional versions, you can try white balancing with different shades of cardboard purchased at a local art supply store. But be careful; if you want a subtle effect, you want cards that are every so slightly off-white.

Exposure
After you set the white balance, you have to set the exposure. Many cameras have automatic exposure circuitry. However, much like the auto-focus mechanisms discussed in the preceding section, this feature often can be more trouble than it's worth.

Automatic exposure, sometimes called auto-iris, determines the exposure by the amount of light coming into the lens. The problem is that the amount of light, particularly outdoors, is continually changing. While it may seem like a good idea to adjust the exposure, it's distracting when the exposure changes in the middle of a scene.

Going back to the sailboat example in the preceding section, a sailboat with a big white sail coming into a scene dramatically changes the amount of light coming into the lens. To compensate, the camera changes the exposure by closing the iris slightly, and the exposure on your subject is compromised. It looks like a cloud has passed in front of the sun, when all that has happened is that the camera has changed the exposure.

Manual exposure is always a better choice if your camera offers it. Setting exposure properly should be done with an exposure meter. Setting exposure can be highly subjective, as videographers regularly overexpose or underexpose for dramatic effect. The procedure for setting exposure manually depends on your camera, the shutter speed, whether you're using filters or not, and a number of other things. You should, however, be able to set your exposure manually by "feel."

Look at your subject, particularly flesh tones if you're filming a person. Do they look right? Try opening your iris to increase your exposure, or closing it a bit to reduce the exposure. Look critically, and make sure you have what you need. If you're unsure, it's better to underexpose than overexpose. You can always add a bit of brightness during editing.

Easy on the pans, tilts, and zooming
Similarly, you should try to avoid panning (moving the camera from side to side), tilting (tilting the camera up or down), and zooming in on or out from your subject. First, these camera techniques are used sparingly by the pros, so if you use them too often or inappropriately, they're a dead giveaway that an amateur is behind the camera. Second, they place lots of motion in the video frame and consequently degrade the quality of your final product.

Camera Techniques

2008-06-04T17:06:00.000-07:00

After you've taken some time to consider and light your subject, you're ready for the "camera" part of the "lights … camera … action" cliché. As mentioned earlier, your camera is probably the most important part of your video production chain, because if your camera doesn't faithfully render your perfectly lit scene, you're starting off with compromised quality, which propagates quality issues throughout your entire video podcast.

In many ways, shooting a video podcast should be no different than shooting for broadcast. You're trying to get the best shot, with plenty of light and color information and lots of detail. Not only does this look best when you're shooting, but it also makes for a better-looking podcast. However, you should take into account a number of things, because the Internet isn't quite ready for primetime, and podcasts are watched on computer screens and portable media players. Bearing this in mind, you should consider things like shot composition and what camera moves you have planned, because they have a direct affect on the quality of your podcast.

Shot composition
The most obvious thing to think about is shot composition. In most cases, your podcast will end up as a relatively small screen resolution, probably 320×240. An iPod screen measures about 2 inches wide by 1.5 inches tall. On a computer monitor, depending on how your resolution is set, this same resolution can be up to roughly 4 inches wide by 3 inches tall. Either way you look at it, it's not the largest screen in the world. Therefore, you probably want to do away with your long shots and concentrate on medium shots and close-ups.

Because podcasting tends to be a very personal medium, the most common video podcasts tend to concentrate on "head and shoulders" framing, where subjects' eyes are located about 1/3 of the way from the top of the screen. One common mistake that amateurs make is to frame the video subject in the center of the video. This makes the subject look short, with too much space above his head. The rule of thirds, shown in Figure 1, will suit you well.

Figure 1: Basic composition using the rule of thirds

To use the rule of thirds, divide your video image into thirds, both horizontally and vertically. You should try to place things of interest on the lines dividing the picture into thirds. Where the lines intersect are particularly good places. If you have a single subject, and you're shooting straight on, try to put the subject's eyes on the top 1/3 line. This makes for a well-balanced image that's pleasing to the eye. It doesn't matter how close or far away you are, the subject's eyes should remain on this line. If you get really close, you'll find that your shot crops off the top of his head (or maybe just his spiky hair). That's okay; if you place your subject at the center of the screen to try and keep his hair in the shot, it will look odd. Use the rule of thirds! It has been serving artists, photographers, and videographers for many years.

Another thing to consider is where the subject is looking. For a single talking head subject, it's best if they face directly towards the camera. In an interview situation, it's better if they are slightly to one side, looking toward where the other person is. In addition, it's most pleasing to the eye for the person to be angled toward the key light so that the part of the face getting the harsh light has the least exposure to the camera.

This may sound a bit complicated, but when you have your equipment set up it's easy to turn people one way or the other to see what effect it has on the shot. This is common practice in studios and is referred to as cheating. Sure, the subject may not be facing directly toward the interviewer, but if the shot looks better on camera, go with it.

Use a tripod
It is absolutely imperative to use a tripod when filming for the Web. Quite simply, using a tripod improves your video quality. Sure, most cameras come with built in handles that make them very portable, and carrying a tripod around is awkward and cumbersome. But the simple fact is that when you encode your podcast later, unnecessary motion will compromise your video quality, and hand-held content has lots of unnecessary motion.

Focus
It may seem obvious, particularly now that so many cameras have automatic focusing mechanisms built in, but it's critical that your subject remains in focus. Properly focused frames have more detail and consequently look better, even after encoding. Ironically, the auto-focus mechanisms of modern digital cameras can cause problems with your focus.

Auto-focus mechanisms work by making assumptions about what is most important in your frame. Things that are bright or moving tend to be interpreted as important. In many cases, this is fine, but if your subject is standing in front of a lake with boats sailing by, for example, the camera has a hard time deciding whether you're trying to shoot the static subject or the moving sailboats. Often the camera becomes confused and continually refocuses on different objects. In most situations, you're better off using the manual focus option if your camera offers one.

Focusing your camera manually is easy if you follow this simple procedure:

1. Zoom all the way in to your subject, and look at something with a lot of detail, such as the eyebrows or hairline.

2. Adjust the focus until it's as sharp as possible.

3. Zoom back out to your original shot composition.

That's it. Provided your subjects don't move too much, they'll stay in focus. If they do move, or if you decide to change the camera position, remember to re-focus each time.

White balancing and exposure
Earlier in this blog, we discussed color, in particular how our brains compensate for the differences in colors under different kinds of light. Cameras attempt to do this, but it's usually a better idea to manually white balance your camera to make sure your color representation is accurate. Manually white balancing a camera is a simple procedure. The idea is to "show" the camera what the color white looks like under the existing light. Given this information, the camera can then adjust its internal circuitry to compensate for the light, and the resulting video image will have faithful color representation.

Light , Color (Basic Video Production Techniques)

2008-06-01T21:46:00.000-07:00

Describing light is pretty hard — after all, physicists have been wrestling with this question for years. Talking in terms of how we perceive light is much easier, and that perception is determined by our eyes. Our eyes have two sets of receptor cells at the back of the eyeball that send information to the brain. Rods are sensitive to motion and light, but not sensitive to detail or color. Cones are more sensitive to color and detail.

Rods can operate at widely varying light levels, but cones require more light, which is why we can see at twilight, but things don't look as colorful. So if we want to record the highest possible video quality, with all the color information, we need enough light so that our cones will respond and relay the information to our brains. This is a fairly long-winded way of saying "use lights." The more light that's present, the more color information and detail we'll be able to perceive.

The amount of light in a video signal is referred to als luminance. The amount of color in a video signal is referred to as chrominance. So when we're working with light, whether we're recording it or manipulating it, we are working with luminance and chrominance. The tricky thing is that luminance and chrominance are intricately intertwined. If you add more luminance, the chrominance is affected. Think about adjusting your television set or your computer monitor. When you turn up the brightness control, colors appear brighter, which may or may not be what you want.

Color
Color is very subjective. We can never truly know how someone else perceives color, but our eyes are constantly adjusting to colors depending on the amount of light available. For example, if someone is wearing a red shirt, his shirt looks red whether he's outdoors in the sunlight or indoors under fluorescent lights. The quality of light that is being reflected off his shirt is completely different in these two situations, but our eyes adjust, and we see the shirt as red.

In a following section, you learn that cameras attempt to do the same thing, but they often need a little help. Making sure your camera is recording color information correctly is known as white balancing your camera. You must white balance your camera, preferably before every shoot, and every time your lighting situation changes.

Using lights
Many cameras are sold on their ability to shoot in low-level lighting situations. Although this may be okay for a home movie, if you're trying to create a broadcast-quality podcast, you need some lights. Shooting with the proper amount of light adds color and detail to your presentation, making it look higher quality. Also, when you encode your video into a podcasting format, you'll find that the higher quality your original is, the higher quality the resultant podcast is.

Discussing the finer points of lighting video is far beyond the scope. Many good books are available on the subject, as well as plenty of lighting professionals who are looking for work. But in the interest of giving you a firm understanding of lighting basics, we discuss the basis for virtually all lighting schemes, which is known as three-point lighting.

Three-point lighting
Three-point lighting is a simple technique that uses three lights to achieve a satisfactory lighting effect. These lights are known as the key, fill, and back lights. Each fulfills a specific purpose:

- The key light is the main light source for the scene.

- The fill light is the secondary light source and fills in the harsh shadows created by the key light.

- The back light is used to separate the subject from the background, by highlighting the shoulder and hair line.

For a simple illustration of three-point lighting, take a look at the three photos in Figure 1.

Figure 1: Three-point lighting in action: a) key light only; b) key light and fill light; c) key, fill, and back light.

In Figure 1a, we see the subject as lit by a single light. We can see the subject, but the left side of the subject is almost completely in shadow. To remedy this, we add the fill light, to fill in the shadows created by the key light (as shown in Figure 1b). The fill light remedies the problem with the shadows we had with a single light source, but the image is very flat. The subject blends into the background, creating a two-dimensional, lifeless image. To remedy this, we add the back light (as shown in Figure 1c). With the back light added, we now see the subject's hair line, as well as highlights on both shoulders. This helps separate the subject from the background and gives us a much more three-dimensional image.

Placement of the three lights is fairly straight forward, as illustrated in Figure 2. The key and fill lights are placed in front of the subject, on either side of the camera. They are usually slightly above the subject, pointing down slightly. The back light is obviously behind the subject, to one side, and usually placed fairly high, aiming downward.

Figure 2: Positioning of lights using three-point lighting

One thing to bear in mind when setting up your lights is the quality of the light. Light sources can be hard or soft. Hard sources cast very strong shadows. For example, if you shine a flashlight against a wall in a dark room, the resultant beam has a defined round shape, with a very distinct edge. Anything in the path of this light creates a very distinct shadow. Soft light sources are more diffuse and cast softer shadows. For example, a lamp in your living room with a lampshade casts a very soft, diffuse light. The shadows cast by this kind of light are very soft and undefined.

In general, you want a relatively hard light source for your key light, a soft source for your fill light, and a very hard source for your back light. The shadows cast by the key light let people know what direction the light is coming from (which is important to our sense of depth) and are softened somewhat by the fill light. We don't want shadows from the fill light to be noticeable. We want the back light to be hard so we can pinpoint it where we need it. We don't want back light spilling all over the place.

Professional lights usually include a lever or dial that allows you to choose between hard or soft light. If you want to soften a hard light source, you can either put a diffusing material in front of it or bounce the light off something reflective. You can purchase attachments for your lights that change a light source from hard to soft.

Another thing to consider is how bright each light should be. The key light should be the brightest, because it's the main light source. The fill light should be lower wattage, so that it doesn't overpower the key light. The backlight should also be lower wattage than the key light. If your lights are all the same wattage, you can compensate by moving lights closer to or further away from your subject. A little adjustment can go a long way. For those of you who remember your physics classes, light falls off using the inverse square law, so double the distance equals one quarter the light.

Of course, in a situation where you have more than one subject, your lighting can be much more complex. You'll very likely need more than three lights. However, three-point lighting is still the basis of most lighting situations. You're always going to need a main (key) light source, fill lights to fill in shadows, and back lights to separate your subjects from the background.

Using reflectors (bounce boards)
One way to economize if you're stuck without enough lights is to reflect light from your key off what are commonly called bounce boards. Bounce boards can be as simple as a piece of light-colored cardboard to purpose-made reflectors that fold up into small, portable packages. Videographers usually travel with a couple of these in their arsenal because they're light and useful in lots of different situations.

This works quite simply. Instead of focusing the key light directly on the subject, you direct it slightly across the subject. Then you can reflect some of this light from a bounce board back toward the subject, as shown in Figure 3. Because the light is being reflected, it's automatically a diffuse source. It's also much lower intensity after being reflected, so it won't compete with the key light.

Figure 3: Using a bounce board to reflect key light back as a fill

This setup is commonly used in video news reel (VNR) situations. Interview teams often consist of a single reporter and a cameraperson, so traveling with a full three-point lighting kit is impractical. Instead, the cameraperson brings a single light on a stand and a bounce board, which may even be held by the interviewer while he's asking questions! It's cheap and portable, and quite possibly ideal for video podcasts.

Shooting outdoors
If you're shooting outdoors, the main problem is that you have no control over your key light, which by definition is the sun. You can't control how bright it will be, or how hard or soft. On a sunny day, it will be a very hard source. On an overcast day, sunlight is very diffuse. It's ironic, because everyone wants to take photographs on sunny days, but sunny days can be the most challenging situations in which to work.

Another problem with working outdoors is power. It's not like you can bring a lighting kit and plug it in wherever you want. You may have the option of battery-powered lights or a generator, but this starts to go beyond the scope of most video podcasts. What you'll most likely want to do is make judicious use of bounce boards to try to even out the lighting available to you. It also can be quite a bit easier to work out of the direct sunlight, and shoot your video in a shady area. You still get the warm quality of the sunlight, but without the harsh shadows that can be hard to overcome.

Shooting Video Outdoors

2008-05-29T21:45:00.000-07:00

Shooting outdoors is a challenge, because so many things can't be controlled. First and foremost, controlling the light is difficult. The quality of light provided by the sun changes during the course of the day, and you never know when a stray cloud will wander in front of your main light source. If the sun is bright, it casts strong shadows and forces people to squint, neither of which you want in your video.

Power can be very hard to come by when shooting outdoors. You can rent a generator or batterypowered lights, but this scale of production tends to be out of the range of most podcasts. You're probably going to have to make due with what you can carry and the light that is available. Bounce boards are invaluable when shooting outdoors, because you can use them to reflect the light from the sun and use it as a secondary light source.

Noise also is a big problem. You can't tell the world to be quiet, unfortunately, and you can't tell the wind to stop blowing. Fortunately, windsocks have been developed that you place over microphones to minimize wind noise. They look like big pieces of wooly foam and do a fantastic job. If you're going to do lots of outdoors work, windsocks are a necessity.

Thinking about Your Video Environment

2008-05-25T21:40:00.000-07:00

The requirements of a video studio are very similar to an audio studio. You want a nice quiet location, with plenty of power. Video studios also require good ventilation, because lights generate lots of heat. You also should find a space with a high ceiling, both for the ventilation and for the lights. Surprisingly, it's best to find a space without windows.

Power
The big power draw in video production is the lighting. Most lighting kits have three lights, with bulbs that are in the 500 to 1,000 watt range. For every thousand watts, you're pulling about an amp of current out of the wall. A three-point lighting kit can easily be pulling over three amps. So you need to make sure that you've got at least a 10-amp circuit going to your studio, because the audio, video, and computer gear also are going to need power. The last thing you need during your podcast recording is for the power to go out.

Ventilation
The bulbs used in lighting kits are fairly inefficient. Much of the energy they're burning up is given off in the form of heat. Point three lights at someone, and you're basically slow cooking them. Your video studio must have adequate ventilation, or you'll end up having to take breaks every 15 minutes to cool off.

One problematic side effect of ventilation is noise. Commercial HVAC (heating, ventilation, and air conditioning) systems are not installed with noise in mind. They hiss, rumble, and rattle all day long, which obviously is a big problem for the audio production. If you're lucky enough to be able to custom-build a space for your needs, be sure to let the contractor know that you need sound attenuation built in to the systems. HVAC noise can be reduced in many ways. It isn't cheap, but if you're building a studio from scratch, you may as well do it the right way.

Light
Because video production is all about light, gaining control over your lighting is paramount for high-quality video production. Controlling the light involves not only where the light is directed, but also the color and quality of the light. For example, you don't want to mix different types of light sources, such as fluorescent and incandescent light. You also don't want to mix sunlight with artificial light. For this reason, it's best to have a video studio with no windows so you don't have to worry about sunlight. Windows also are a notorious source of noise, which is another reason to avoid them.

Video editing software & Accessories

2008-05-23T21:37:00.000-07:00

Video-editing software
You definitely need some video-editing software to create your video podcast. Video-editing software allows you to edit your video, adjust the video quality, and do rudimentary audio editing (on some platforms). A number of editing platforms are available; these are some of the most popular:

Final Cut Pro (Mac): This is the flagship of Apple's video-editing suite.

iMovie (Mac): It's no Final Cut Pro, but for podcasts, it's probably all the video editor you need. And because it's from Apple, you can bet that there's tight integration with the iPod.

Adobe Premiere (PC): Adobe Premiere has been around since video editing on desktops began. It has very tight integration with Adobe Audition.

Sony Vegas (PC): Vegas is tightly integrated with Sony Sound Forge. In fact, Vegas has much of the audio-processing capability of Sound Forge built in.

Ulead Video Studio (PC): This software has a great price and includes output templates for iPods and SmartPhones.

Cinelerra (Linux): That's right, now you can do video editing on your favorite free operating system.

Accessories
Along with all the goodies discussed previously, you need a good selection of cables to connect all your equipment. As with audio, don't skimp on cable quality. You're better off buying an expensive cable that lasts longer. Depending on the scale of your production, you also may want to consider a number of other accessories. Many of these are used either to improve your video quality or to compensate for a troublesome video issue.

Processing amplifier (proc amp): Proc amps allow you to tweak the video signal in real time, saving you the hassle of having to do it later.

Camera filters: Filters can compensate for your lighting situation and thereby enhance your video quality.

Gels and diffusion materials: If you're using a lighting kit, gels and diffusion materials help you control your light.

Flags: Flags are used to direct light so it doesn't go where you don't want it.

Bounce boards: Bounce boards are used to reflect light where you need it. They can be as simple as a large piece of light-colored cardboard or custom-made versions that have different colors on either side to be used in different situations.

Video "humbucker": Video cables are susceptible to noise, particularly from nearby power cables. This noise shows up in the picture and degrades the quality. Humbuckers filter out this noise.

"Green screen" facilities: Using a technique known as "green screen," you can film your subject against a green wall or background, and then during the edit phase a different background can be substituted for the green background.

Gaffer's tape, clothes pins, cable adapters, etc.: Every videographer has a kit bag full of adapters, tape, and lots of other things that are useful during a shoot.

Most of the items in this list can safely be skipped for your first few video productions. Most videographers' kit bags are the result of years of accumulation, having had to deal with a number of issues over the years. You should definitely make sure you have plenty of spare cables and a roll of gaffer's tape, because as the saying goes, anything can be fixed with enough gaffer's tape.

Video mixers & Video interfaces/capture cards (Video Production Tools)

2008-05-21T21:32:00.000-07:00

Video mixers
If you're going to get fancy with your podcast and shoot with multiple cameras, you'll probably want to buy a video mixer. Video mixers, like audio mixing desks, take multiple video inputs and allow you to switch between them. They also offer special effects like picture in picture and cross fading between sources (see Figure 1).

Figure 1: Focus Enhancements MX-4 video mixer

Tip Of course, you can get the effect of a multiple-camera shoot by being clever with your editing. This common technique is used in news gathering, where the interviewer asks questions off camera while the interviewee is taped answering the questions. Then, when the interview is finished, the interviewer is taped asking the questions, and the result is edited to look as if two cameras were used during the interview.

Most cameras used for podcasting applications are camcorders, so they record the signal to tape. The video signal can also be recorded directly onto your computer via the FireWire output. It's always a good idea to record to tape as backup even if you're recording directly to your computer. If you're using multiple cameras and a video mixer, you also may want to consider recording the output of the mixer to a video tape recorder (VTR). Otherwise, you must digitize the tapes from all your cameras to recreate the live edit if something goes wrong.

Of course, you can purchase a stand-alone video deck, or more interestingly, you can now record straight to an external drive such as Focus Enhancements' FireStore (see Figure 2). These units record digital video from a FireWire cable so you don't have to digitize later. You just attach the FireStore to your video editing station, and it appears as an external drive.

Figure 2: Focus Enhancements FireStore FS-4

Monitoring
Even though many cameras come with flip-out LCD screens that allow you to monitor your video, these screens really aren't good enough for quality control. You should buy a small monitor (which in the video sense is a small video display) so you can check the lighting of your subjects. If you aren't shooting on location, you can use a television with an auxiliary input, but be careful: Televisions are built to flatter the video image and often are far out of alignment from the broadcast standard. If you go this route, buy one of the kits that help you calibrate your television display.

Video interfaces/capture cards
At some point, you have to get the video signal out of the camera and into your video-editing workstation. If your camera and workstation both have FireWire, you're in luck: All you need to do is connect them with a FireWire cable, and you can import the video data directly. If your workstation doesn't have a FireWire card, you can pick one up for less than $50 these days.

If your camera doesn't have a FireWire output, you can get a digital video converter box that takes an analog video signal as input and outputs a DV signal via FireWire (see Figure 3). The nice thing about having a digital video converter is that you can plug any video signal into it, such as a DVD player or old VHS player. Alternatively, you can buy a video capture card. Video capture cards take analog video as input and digitize it to your hard drive. Video capture cards range in price from under $100 to many thousands of dollars. For the most part, however, the convenience of DV cameras with FireWire outputs is hard to beat.

Figure 3: The Canopus ADVC-300 Digital Video Converter

Tripods & Lights (Video Production Tools)

2008-05-19T18:26:00.000-07:00

Tripods
A good tripod is far more important than you think. In fact, you should probably consider spending about one-fourth of your total camera budget on a tripod. Although it may seem hard to believe that a $500 tripod is that much better than a $50 tripod, the difference is immediately noticeable to a professional videographer. We learn more about the importance of a tripod later. For now, just put it on your shopping list.

Lights
When we're talking about video, we're talking about light. When you're shopping for a camera, you'll probably see all kinds of facts and figures about various models' performance under lowlight conditions. Don't believe them for a second. Manufacturers make all sorts of wild claims about low-light performance. The truth is that cameras don't work well in low-light conditions. The cheaper the camera is, the worse the performance.

Luckily, lighting kits are available for precisely this reason. Using a lighting kit gives you control over the light, which in turn gives you control over the quality of your video image. A decent lighting kit runs about $800 and comes in a snazzy flight case so you can lug it with you wherever you need it (see Figure 1).

Figure 1: A portable lighting kit (Lowel)

If you're on a really tight budget, you don't have to shell out for professional lighting. Shop lights purchased from your local hardware store can be used, though they don't have anywhere near the control that professional lights do. Typically, they produce a fairly harsh, unforgiving light but with creative use of diffusion and positioning, you can get lots out of a very small investment.

Video Production Tools : Cameras

2008-05-15T20:39:00.000-07:00

Although podcasting was originally conceived as an audio-only medium, this is no longer the case. Video blogging, or vlogging, is currently all the rage and is bound to get more popular. With the ever-expanding deployment of broadband connectivity and the plunging costs of digital video cameras, video broadcasting is within reach of just about anyone.

Sort of. As powerful as modern digital video cameras are, the affordable "prosumer" versions can't create a broadcast quality video, at least not without a little help. When the digital video format first appeared in the 1990s, it was laughed out of newsrooms across the country because the quality was thought to be too crude for broadcast. Within a few years, the convenience and immediacy of the format has made believers out of even the most demanding television producers. These days, a good portion of reality television programming is shot using the digital video format.

Of course, it doesn't hurt that the quality of digital video equipment has improved since the first few cameras appeared. You can now find cameras that offer fine-grained control of the image, as well as cameras that accept different lenses. Even more exciting, with the advent of HDV (High Definition Digital Video), you can shoot true widescreen video on a budget that doesn't require venture capital. To begin, however, you're probably going to be looking at an inexpensive camera and some support equipment. This post surveys what's available at the moment and discusses what features you should look for when you go shopping.

Choosing the Appropriate Equipment
Video production has some basic requirements. Obviously, you're going to need a camera and something to mount it on (we explain later why handheld video is a no-no). Because video is all about light, your video quality depends on the amount of control you exercise over your light. This means you should have some lights at your disposal, along with bounce cards and flags to stop light going where you don't want it to go. You also need plenty of spare cables and some other auxiliary video equipment. Good video production starts with your camera.

Cameras
A good camera is the single most important piece of equipment in your video signal chain. The camera records the incoming light, digitizing it and storing it as a digital video signal. The camera is therefore of paramount importance, much like a microphone is to audio. If your camera does a poor job of converting the incoming light into digital video information, you start off with lowquality video. Correcting digital video imperfections is very difficult. There are various methods of video processing available, but video is nowhere near as forgiving as audio. It's better to start off with high-quality video than to plan on fixing it later.

Video formats
The number of video formats available at the moment can be confusing to the neophyte. This is due partially to rapidly evolving digital video technology, and also due to manufacturers looking for an edge over their competition. Table 8.1 lists the most common video formats used in budgetconscious applications.

If you're just starting out, you probably want to start off with whatever camera is lying around or whatever you can borrow. If you're the slightest bit serious about a video podcast, you should consider investing in a decent-quality DV (digital video) camera. They're ubiquitous and have a number of features that are perfectly suited to digital video production. (These are discussed in the next section.) DV cameras are available at numerous price points, with higher-priced models offering higher image quality and better build quality.

What to look for in a camera
Digital cameras come with a bewildering array of features these days. Some of these are just marketing hype and of little use to anyone, never mind an aspiring video podcaster. Essentially, two main things determine the quality of your video:

Lens quality: Higher-priced cameras have better lenses, and better lenses provide better image quality.

Image capture mechanism: DV cameras use charge-coupled devices (CCDs) to convert the incoming light into a digital signal. The size and number of CCDs the camera uses determine image quality.

Cheaper DV cameras use a single CCD to capture the video, whereas more expensive versions use three separate CCDs and divide the incoming light into red, blue, and green components for a higher-quality image. You should look for a camera with three CCDs if you can afford it; the higher-quality video image is worth the investment.

When it comes to the lens, each manufacturer sings the praises of their lens for "superior color and image quality." Lens quality can be very subjective — it's usually a good idea to hit a few camera ratings sites to see what people have to say about the latest and greatest models. You can find a number of these sites: The granddaddy is http://camcorderinfo.com.

Other features you should be concerned about are listed here. The advantages of some of the features discussed here may not be very apparent when you first start out, but become important as you become more familiar with your camera and want to get the most out of its capabilities:

Manual adjustments: Many DV cameras hide functionality deep in an on-screen menu that may or may not be accessible after you're recording. Having buttons and switches easily accessible is a big plus.

XLR inputs for audio: You never want to use the microphone on the camera, because they're low quality and designed to pick up everything in the room. Instead, use a professional mic or two; these generally require an XLR input. Otherwise, you'll have to invest in an external add-on box to make the XLR cable compatible with the awful ⅛ mic inputs that some cameras have.

IEEE 1394 (FireWire) output: A FireWire output allows you to transfer the video from the camera directly to your computer without requiring a video capture card. If a camera doesn't have one of these, don't even think about buying it.

There are so many cameras to choose from and so many mew models coming out every year that it's virtually impossible to recommend any particular models, for fear that they will be outdated by the time you read this! However, a number of cameras at the slightly more expensive end of the DV range are perennials. Even though Sony, Canon, and Panasonic keep bringing out new models, the cameras pictured in Figure 1 seem to stick around. They're all well proven by years of streaming video production.

Figure 1: DV camera workhorses: Sony PD-150, Canon XL-2, Panasonic HVX200

Using Podcast-specific Software : WebPod Studio

2008-05-10T16:50:00.000-07:00

WebPod Studio
WebPod studio offers audio and video podcast production capabilities. It's available in three different versions ranging in price form $89.95 for the basic edition to $189.50 for the Enterprise edition. The main screen displays a number of icons along the top showing all the different things you can do, along with text links in the main part of the interface with links to wizards that walk you through each process. A sample screen is shown in Figure 1.

Figure 1: WebPod Studio helps you create audio and video podcasts.

WebPod Studio offers no advanced editing or signal processing tools, but it does offer a few features that set it apart. First, it offers teleprompting, so you can enter a script for your podcast. It also imports PowerPoint slides and converts them to slides you can use in a video podcast. It also creates RSS feeds and automatically sends your files to your server.

Using Podcast-specific Software : Castblaster

2008-05-08T04:47:00.000-07:00

Castblaster
Castblaster is similar to Podcast Station in that it provides a simple user interface for you to create and publish your podcasts. A sample screen is shown in Figure 1. It also offers cart and deck functionality, enabling you to easily insert short audio pieces like sound effects or promotional pieces, as well as longer pre-recorded pieces such as songs or interviews. It has faders to control the volume of your microphone and your headphones, as well as the volume of the pre-recorded pieces.

Figure 1: Castblaster is a simple, no-nonsense way to create and publish podcasts.

Castblaster offers rudimentary editing, but does not offer any signal processing. Castblaster offers a publishing interface that automatically creates your RSS file, encodes your audio into MP3 format, and places the files on your server. It has tight integration with http://PodShow.com, because Castblaster is distributed by the good folks there, for $50.

Using Podcast-specific Software : Podcast Station

2008-05-06T16:43:00.000-07:00

Using Podcast-specific Software
Assume you're using a standard audio-editing program to record and edit your podcast. However, a number of podcast-specific software packages include audio-processing capabilities, along with other capabilities that may be of use to you. This section discusses a few of these solutions. By the time, even more will be available.

Podcast Station
Podcast station, from Audion Laboratories, is based on its VoxPro software, which is a professional broadcasting package designed for recording and editing radio programs. Although it's priced at a fraction of the cost of VoxPro, it still offers a host of features that podcasters will find valuable. The Podcast Station interface is simple and intuitive. A sample screen from Podcast Station is shown in Figure 1.

Figure 1: Podcast Station offers radio station functionality in a single screen.

All your recording and editing takes place on the main screen. A large "button block" contains oneclick buttons for just about every operation you'll need. You can record from any soundcard input directly to the video time line and then insert songs, sound effects, or any pre-recorded files using the cart and deck buttons. After your program is on the time line, you can apply audio effects like EQ and compression.

Podcast Station is a well thought-out product with lots of nice touches. For example, if you rightclick any of the faders (Podcast Station calls them sliders), the fader does a nice quick fade out, for example if you need to cough or you want to quickly fade out from an interview. Right-click the fader again, and it is restored to its previous level.

Another great feature is the ability to undo. This is similar to the undo abilities of other audio-editing programs, but Podcast Station goes one better — you can undo days or weeks later. Podcast Station keeps track of everything you do and stores it in the file along with your audio, so you can undo all the way back to your original if you need to.

Podcast Station also has a nice wizard-driven publishing feature, shown in Figure 2. It automatically generates your XML file, compresses your program to MP3 format, and sends your files up to your Web site. On top of all this, the folks at Audion Labs have a good sense of fun that is reflected in the documentation and tutorials that are provided. This is hard to beat for only $59.

Figure 2: Podcast Station also offers encoding, RSS authoring, and FTP through its wizard-driven publishing interface.

Multi-track Audio Production

2008-05-05T20:11:00.000-07:00

When you begin to create podcasts, you'll probably use a simple stereo audio editing program. As your productions become more professional, you may be tempted to move up to a multi-track audio program. Multi-track systems offer a number of benefits, the most important one being the ability to separate the elements of your podcast onto separate tracks. This, in turn, enables you to work on the tracks individually, applying tailored effects such as EQ and compression to each track on an individual basis.

Things to consider
Now that you're graduating to the world of multi-track recording, the first thing to do is label them appropriately so you know what is on which track. Sure, you say, I'm always going to put my mic on track #1, the guest on #2, and the music on track #3. Well, what happens when you add a telephone hybrid? What happens if you're sick and your buddy agrees to finish off one of your podcast productions for you? Believe me, it may seem pedantic, but labeling your tracks will save you lots of headaches in the long run.

Next, to take full advantage of a multi-track recording setup, you'll need an audio interface capable of multiple outputs and a mixing desk with multiple outputs. Each track can be assigned to a particular input, as shown in Figure 1. If you have only a stereo audio interface, you can still record to separate tracks, provided that you pan the two separate channels hard left and hard right on the mixing desk, and then record the left channel on one track and the right channel on another.

Figure 1: Sony Vegas multi-track software

After you have your audio recorded, bear in mind that the overall level will be cumulative. You have to be careful when you mix all your tracks together so that you don't end up with too much level. This can often happen if everyone talks or laughs at once. Suddenly, you have not one track but two or three, all feeding your master mix. This is why you'll want to think about using a compressor on each track or across your master mix if your software allows it.

Multi-track audio software is different in this manner, in that the effects you apply are not performed on the file. Instead, they are applied in real time as you play back the audio. In addition to being able to apply effects to each track, you can also apply effects to the master mix. In this situation, you could apply light compression to each of the input tracks and then a limiting compression to the master mix to make sure you never go into distortion.

Multi-track templates
If your podcast follows a particular format, for example if you use the same intro and outro music for each show, you can save time by creating a multi-track template that you can drop (or record) your audio into each week. Instead of having to worry about finding your theme music and worrying about levels, you just place the theme music on a separate track and then record the rest of your podcast on separate tracks. When you record using multi-track software, tracks that are not in record mode simply play back, so you'll hear the theme music in your headphones, and as it fades out, you jump in with your introduction.

When to Do Signal Processing

2008-05-03T16:40:00.000-07:00

When to Do Signal Processing
Given all the signal processing options at our disposal, you may very well ask when they should be done and in what order. There really are no hard and fast rules, though we can provide some guidelines. The thing to remember is that the cumulative effect of all your signal processing is going to depend on how each step in your signal processing affects the next step.

For example, if you recorded your original audio at a low level, you may be tempted to normalize it to start. However, if you're planning to add some EQ, be sure to leave headroom, because you may add to the overall level. If you're going to use compression and EQ, remember that the compression is going to warm up your bottom end and make your audio sound fuller, so you may not need to add too much bottom end. Conversely, because compression is going to fatten your sound, you may be tempted to add a touch of high end to compensate for any lost sparkle.

Audio Processing Trick : Normalization, Noise Reduction,

2008-05-02T04:26:00.000-07:00

Other Audio Processing Tricks
EQ and compression are the most common tools that audio engineers use to process their audio. But they're not the only tools, by any means. Here are a few more that you may find handy in your day-to-day podcast production.

Normalization
Normalization means turning the audio up until the peaks are at a given level. This can be very handy, for example, if your record level is a bit low and you want to turn it up but not so much that it distorts. The simplest way to do this is to use Normalization.

Figure 1 shows the Sound Forge Normalization window. It's very straightforward; you can choose what level you want the file normalized to using the slider at the left. In this illustration, you'll see that we're normalizing to -0.5dB, not 0dB. You can simply normalize to 0dB, but if you do, you have no headroom. If you're doing normalization as your very last step, you don't need headroom. If you're planning on adding EQ, you should probably normalize to -3dB or even -6dB to leave headroom for later EQing.

Figure 1: The Sound Forge Normalization window

Of course, this is assuming you're using Peak Level normalization, which analyzes the entire file and raises the volume until the very highest peak is at the required normalization value. If you have one small section of the file that is loud, and the rest is very quiet, normalization is going to get you only so far. You'll have to use some compression to even out the levels throughout the file.

Another kind of normalization that's very handy if you plan on playing music is RMS normalization, shown in Figure 2. RMS normalization measures the overall power of a file, as opposed to just looking at peaks. If you combine this with an equal loudness contour, RMS normalization gives all your audio files the same apparent level.

Figure 2: Use RMS normalization with an equal loudness contour to make all your music files sound as loud as each other.

Note : RMS stands for root mean square, which is a mathematical measure of the magnitude of a varying quantity. RMS is calculated by finding the square root of the mean of the squares of a set of values.

Audio with lots of low frequency content sounds louder to us, so even though two files may "look" the same in an audio editor (both have peaks at -3dB), one may sound much louder due to its tonal character. RMS normalization using an equal loudness contour takes into account how sensitive our ears are to particular frequencies and sets levels accordingly.

Gating to remove background noise
A noise gate mutes the audio signal when the level falls below a certain level. For example, if you're doing an interview in a room with a noisy ventilation system, you could try using a gate to get rid of the noise when you're not talking. Setting up a noise gate involves setting a threshold and attack and release times, similar to a compressor, as shown in Figure 3.

Figure 3: Using a noise gate to remove unwanted background noise

Gating is best used when the background noise is very low; otherwise, the gating effect will be noticeable, because oddly enough our ears will notice the noise disappearing, and this can be more annoying than a constant background noise. If you have a serious noise problem, you may be better off using noise reduction.

Noise Reduction
Noise reduction is a sophisticated process that attempts to remove noise from your audio without affecting the rest of the content. As you might imagine, this is a very difficult undertaking. Noise reduction algorithms usually work by taking a "noise profile" or "noise print," which is used to determine the frequency content and level of the noise. Taking a noise print involves identifying a section of the audio file that contains only noise. The algorithm can then use this information to analyze the file and remove what it thinks is noise. Figure 4 shows the noise reduction windows for Audacity and Sound Forge.

Figure 4: Noise reduction, using Audacity and Sound Forge

You can see that both involve a two-step process — first getting a noise print, and then running the resulting filter across the entire file. Noise reduction can be incredibly effective for steady background noise. However, be aware that the urge to remove background noise can sometimes lead to audio that sounds too thin. The key is to use it sparingly, so that your audio sounds cleaner but not antiseptic and hollowed out.

Stacking and Multi-band compression

2008-04-29T09:57:00.000-07:00

Stacking compression
You may have noticed when you were playing around with compression in the last setting that a little bit of compression sounds good, but too much starts to sound noticeable. Sometimes, however, you may need a little more than light compression. The problem is that if you use a heavier setting, the effect starts to become too noticeable. One way around this is to stack your compression effects.

It's a really simple concept; apply a light compression across your entire file, and then apply another light compression. Lightly compressing the material twice is a much subtler effect than heavily compressing once. In fact, this approach is very common in recording applications. Audio engineers lightly compress material that is being recorded, to provide a little control over levels. Then, after the material has been edited, they apply additional compression to give the program that extra bit of presence.

Another approach, used in multi-track recording situations, is to use different compression effects on different tracks, and then to have a limiter placed across the master mix, to make sure the final mix never goes into distortion.

Multi-band compression
All the compression we've been talking about up to this point has been compression that analyzes the entire frequency range when determining what has exceeded the threshold. There are specialized compressors that break the frequency range into a number of different bands and then compress them all individually. Radio stations use ridiculously expensive multi-band compressors and set them up to try to get a unique, signature sound. (All they're really doing is competing to see who sounds loudest.)

One area where multi-band compression can be incredibly useful is as a corrective measure, in particular to deal with microphone pops and sibilants problems. In the EQ section, we discussed how you could deal with pops and "ess" sounds by turning down certain frequencies at the instant the problem syllable appears. A multi-band compressor does this for you automatically.

Figure 1 shows Sony Sound Forge's multi-band compressor, using a preset called "Reduce plosives and sibilants." It's using two bands, both of which have very fast attack and release times, because we want the compressor to react immediately. Band #1 is set to low shelf mode, meaning it monitors all frequencies below the shelf frequency, which in this case is 600Hz. Band #2 is set to notch mode, with a moderate Q of one octave, centered on 5KHz. When I preview audio, I can see the second band being compressed when the narrator pronounces "ess" sounds. Because my narrator hasn't popped the mic, the top band doesn't do much of anything. If you have a guest who has a problem with sibilants, you can use the de-ess preset (yes, that's the technical term for this) to get rid of the problem. Fabulous.

Figure 1: Using Sony Sound Forge's multi-band compressor to fight pops and sibilants

Compression: A step-by-step example

2008-04-27T11:24:00.000-07:00

Now that you know a little bit about how compression works, it's time to play around with it to see how it affects the sound of your podcast. For this example, we'll be using the compressor that comes with Audacity.

1. Open Audacity, and open your podcast file.

2. Select the entire file by pressing Ctrl-A (Opt-A on a Mac). Remember that Audacity doesn't expose the effects until you highlight a section of your audio.

3. Select Compressor from the Effect menu. This brings up the Dynamic Range Compressor window, as shown in Figure 1.

Figure 1: The Dynamic Range Compressor in Audacity

4. You can see in Figure 1 that the default settings for the Audacity Compressor is a 2:1 compression ratio, a -12dB threshold, and a .2 second attack time. (This plug-in doesn't have a release time setting.) In fact, this is a nice moderate setting that may work just fine for your content. However, you may want to experiment with the settings to see what changing the threshold, ratio, and attack times do to the sound of your file.

Audacity's Dynamic Range Compressor settings are adjustable in increments. For example, the ratios are variable in .5 increments (1.5:1, 2:1, 2.5:1, and so forth), and the attack times in tenths of seconds. Try changing the compression settings to a 4:1 ratio and a .1 second attack time. Preview the audio. Hear a difference?

In fact, 100 milliseconds is really too slow of an attack time. To hear why, try changing the threshold to something really low, say -30dB. Preview the audio. Hear that? The audio starts off loud, and 100 milliseconds later the compressor kicks in. The compression effect is audible, because the attack time is too slow. However, if you raise the threshold up to say -15dB, the effect may not be as audible. You should be able to find a threshold that works in conjunction with the sluggish attack time.

How compression works

2008-04-25T09:05:00.000-07:00

How compression works
Most compressors offer the same basic controls, which allow you to set the following:

Threshold: Where the compression effect kicks in

Ratio: The amount of compression applied above the threshold

Attack and Release times: The length of time after the threshold is crossed that the effect is applied and removed

Figure 1 illustrates what different compression curves look like. Looking at the curve, you'll see that signal levels below the threshold are unaffected, and signal levels above the threshold are attenuated. The higher the compression ratio is, the more attenuation. When the compression ratio is high, it is known as limiting, because it more or less prevents the audio from exceeding the threshold.

Figure 1: Compression curves with different compression ratios

Setting a threshold
To illustrate how different threshold settings affect the output, let's assume that we're working with the audio file illustrated in Figure 2. We can see that this file has peaks as high as -2dB, but the bulk of the file is below the -10dB mark. If we want to compress this file lightly, we should set a threshold in the -6dB to -10dB range. Figure 3 illustrates compression applied to this file using two different thresholds, -6 and -20dB.

Figure 2: The audio file from Figure 7.5 after compression using a threshold of a) -6dB and b) -20dB

Figure 3: The audio files from Figure 2 after applying compensating gain

What is immediately apparent is that the file in Figure 2b has been compressed far more heavily than Figure 2a. We need to apply some gain to restore these files to their former levels. Figure 2b has far more headroom, so we can apply much more gain. After applying gain, we end up with the files illustrated in Figure 3.

These files are both much louder than the original, but if you look closely at the figure on the right, the entire file is loud. It doesn't have any dynamics left, because the dynamic range has been compressed. To be honest, this file might be a little too compressed. Files that have been over-compressed are fatiguing to listen to, because EVERY SINGLE SYLLABLE IS LOUD. Think of drive-time radio programs; they're highly compressed, because the DJs are going absolutely nuts in the studio. The idea is to compete with all the noise of traffic and to keep you awake on your drive to and from work. But this is not the type of programming you really want to listen to all day long (see the "Compression: How Much Is Enough?" sidebar).

If your original audio file is well recorded, you should have peaks in the -3dB to -6dB range. Choosing a threshold in the -6dB to -10dB range is a safe starting point. This way, you're only compressing the loudest sections of your file, leaving most of your file untouched. If you find yourself dropping your threshold much below that, you may consider revisiting your signal chain to figure out why your recording is so quiet in the first place.

Setting a ratio
The ratio setting determines how much compression is applied over the threshold. For example, a 2:1 compression ratio means that for every 2dB by which the incoming signal exceeds the threshold, only 1dB of gain is applied. Ratios up to around 4:1 are mild and can be used safely, provided you set a sensible threshold. Ratios in the 4:1 to 10:1 range are fairly heavy and should be used with caution. Any ratio over 10:1 falls into a special category known as limiting.

Limiting can be useful as a preventative measure, but it isn't appropriate as your main form of compression. For most applications, start off with a ratio of 4:1 and experiment with using slightly more or less until you achieve the effect you're after. In particular, voices are particularly compression tolerant, so if you don't have any music in your podcast, you may be able to use more compression (see the "Compression: Voice versus Music" sidebar).

Setting attack and release times
The attack and release times control how quickly the compression effect is applied to signals that exceed the threshold you set, and how quickly the signal level is returned to the original input. For most content, you want a quick attack time, so signals that exceed the threshold are immediately attenuated. For the release time, you want something a bit longer, so the sound doesn't abruptly get returned to the original level.

This is fairly self-evident from the attack and release controls. The scale on the attack control knob generally is in milliseconds, and the scale on the release knob is in seconds. Start with a quick attack, say 10-20 milliseconds, and a gradual release around 500 milliseconds. These settings should work for most podcasting content, but don't be afraid to play around with your compressor to see how these settings affect the compression.

Compression : Why use compression?

2008-04-22T12:27:00.000-07:00

Compression
Compression is a form of dynamics processing, meaning that it deals with the overall levels in a file. Compression automatically turns down sections of your audio file, based on settings you specify. Think of it as an automatic volume control. In fact, you may have run into Automatic Gain Control (AGC) on a piece of hardware you own. Many portable tape recorders have an AGC circuit built in to the microphone. This is a fancy marketing term for a compressor. The AGC circuit ensures that all sounds are picked up and that sounds don't get so loud that they distort the microphone input.

Most compressors offer a number of controls that enable you to set where the compression effect kicks in and how drastic it is. But before we get into the details of how compression works, let's talk a little bit about why compression is useful.

Why use compression?
At its most basic, compression is useful as a safeguard against distortion. A compressor automatically adjusts the signal level when it exceeds a certain threshold, so that a guest who suddenly gets excited won't send your levels into the red. For this simple reason, compressors are very useful in live situations, when you may not be able to control situations as tightly as you'd like to.

Compression also is useful when working in lower fidelity environments, because it allows you to match the dynamic range of your production to the available dynamic range of the equipment on which it is played back. CD-quality audio has a very large dynamic range, and provided you're listening in a quiet environment, you can hear very quiet sounds as well as very loud sounds coming off a well-produced CD. This simply isn't the case for most podcasts.

First, most podcasts are played back on desktop systems, very often in slightly noisy environments. So if your podcast has very quiet sections, people will have a hard time listening, because they'll either have to turn the volume up temporarily or shush the people around them. And if you're encoding at a lower bit rate (96Kbps, 64Kbps, or even 32Kbps), the dynamic range simply isn't that great. The encoding software uses volume as a determinant of importance, so quieter sections won't sound as good as the louder sections.

If the quieter sections of your podcast are going to be difficult to hear, then you want to turn those sections up, right? Sure you do. You want the overall level of your file evened out, so you don't have large differences between the loud sections and the quiet sections. You want the dynamic range compressed. This is precisely what a compressor does.

Figure 1 illustrates the dynamic range and headroom of a file. We'd like to turn up the quiet sections of this file, but at a certain point, the louder sections will go into distortion. Using a compressor, we can turn the file up and ensure that the loud sections don't go into distortion, because the compressor turns those sections down automatically.

Figure 1: The dynamic range and headroom of an audio file

The final reason to use compression is because we're used to hearing compressed audio on all the traditional broadcast mediums. Radio and television use compression liberally. This is partially for the protective reasons discussed previously, but also because of a particular side effect of compression. Compression tends to make things sound fuller, because it brings up the bottom end of the audio signal. Between the protective qualities of compression and the added warmth, this combination is hard to beat.

Advanced EQ techniques

2008-04-20T05:39:00.000-07:00

EQ also can be used as a corrective measure. The techniques described in the preceding sections aimed to improve the overall sonic quality of your audio by focusing on what you wanted to be heard. You also can use EQ to remove extraneous noise that you don't want in the file.

Clearing up noise
If you recorded your audio in a noisy environment, you can use EQ to get rid of some of the worst noise. First, roll off all the low frequencies. You should do this regularly to all frequencies below 60Hz, because they're generally not reproduced by most systems. You can roll off more if you're dealing with serious noise. For example, traffic outside a busy city window will be audible as a steady low rumble, with the occasional siren or horn. If you roll off more of the bottom end, the sound of the traffic will be less audible.

Similarly, you can roll off high frequencies if you have noise problems such as air conditioning or tape hiss. In the preceding example, we boosted all frequencies above 5KHz to give the file some air; clearly, this is not something we'd want to do if we were in a noisy environment. Of course, we could have used the shelf to roll off all high frequencies above 8KHz or so and added a slight lift around 4–5KHz. Very little important voice information is in the range above 10KHz, so if you have noise problems, you can safely roll this off without any damage to the intelligibility of the audio.

Of course, in extreme situations, you can get pretty savage with EQ if necessary. For example, sometimes news reporters outside during a storm sound like they're talking through a telephone line. This is because the audio engineer at the station has rolled off all low frequencies and high frequencies, leaving just the mids.

Pops
Sometimes, a pop sneaks into your audio file, even if you're using a pop screen. If you zoom in to your audio file and look at the offending pop, you'll see that it's a very brief, very loud low frequency burst. You can highlight the offending word (or even syllable) and roll off the offending bass frequencies, as shown in Figure 1.

Figure 1: A pop is visible as a short, loud low-frequency burst, which can be fixed with EQ.

Experiment with different amounts of roll-off at different frequencies. You'll find that if you roll off too much, you get rid of the pop, but the result may sound unnatural. Find a good balance between removing as much of the offending pop as possible, while retaining the natural feel of the original.

Dealing with sibilants
Some people have a problem with sibilants, which are consonants like the letter "s" ("d" and "t" can also be a problem but usually nowhere near as much) that contain a burst of high-frequency information. This is audible as a whistling or, well, an "ess" sound. A little of this is natural, but too much is annoying. Some people actually whistle when they pronounce these consonants, which is an extreme version of the same problem. Because this is usually a very localized problem, it can be dealt with using EQ.

Sibilants usually are most prominent around 5KHz. Just like the preceding example where a word was highlighted and bass frequencies were rolled off to get rid of a pop, you can highlight a word and try to cut the offending frequency. Dealing with sibilants is more troublesome than popping, because our ears are very sensitive to high frequencies, and even if it's only a momentary change, our ears may notice that the sound has changed. Not only that, but if someone has trouble with sibilants, it usually manifests itself throughout the entire interview — and the letter "s" is very popular in the English language. In general, if you want to deal with sibilants, you should use a de-esser. That's a fancy term we audio engineers made up to describe a "frequency dependent, side chain controlled compressor." De-essers are explained in the compression section, which comes next.

EQ: A step-by-step example

2008-04-18T13:48:00.000-07:00

This section steps you through the EQ process, with both graphic and parametric EQ. We'll assume that this is a male voice track that needs a little bit of sparkle. We're trying to do the following:

- Add a bit of warmth to the bottom end.

- Add a little clarity to the midrange.

- Give the vocal a bit of air, a little extra shimmer.

We're going to assume that you're using a software equalizer, though there's no reason that this couldn't be done using a hardware EQ. Also, the frequencies we're choosing in this example may not be the best frequencies for your audio, although they're probably a good place to start. Remember: Use your ears:

1. First, roll off the extreme low end. Chances are good (unless you have an extremely deep voice) that there is no information down here, except for possibly some room noise. Let's roll off everything below 60Hz.

On a graphic EQ, push down the faders below 60Hz. If you have more than one, start off gradually, rolling off about 3dB at 60Hz and then increasing the roll-off with each lower frequency.

On a parametric EQ, choose a high-pass filter at 60Hz and roll it all off. Shelving EQ has gradual roll-off built in.

2. Listen to your audio. You shouldn't hear much of a difference, if any. That's fine. You may hear a slight clearing up of the sound, and if so, that's even better.

3. Next, work on the midrange, because it's the most important. To give a voiceover a slight lift, you can boost the upper mids in the 2 – 4KHz range.

On a graphic EQ, pick a frequency in this range and boost it significantly, say 6-10dB. Preview your audio. Return that frequency to no gain, and try boosting the frequencies on either side, previewing each time. When you find the frequency that sounds best for your content, boost it 3dB and then boost the frequencies on either side 1.5dB, so there's a nice gentle lift. Preview the audio, and make sure it sounds good.

On a parametric EQ, choose a narrow Q and boost a frequency in the 2 – 4KHz range. Preview your audio. Try moving the frequency setting up and down, until you find the right frequency. Preview the audio each time you change the frequency. After you settle on a frequency, widen your Q to approximately 1.5. Boost 3dB, and give your audio one last preview to make sure you're doing the right thing.

4. Now listen to the low mids. The low mids are roughly where the sounds "er" and "uh" live. (If you've ever seen a sound check before a live gig, you'll hear the audio engineer making these sounds in the mics to check the EQ.) These frequencies give our ears information about the size of a room. You can often clear up a mix by cutting here, but be careful: You can make your audio sound too thin if you cut too much.

On a graphic EQ, you can experiment with cutting around 300Hz. You can do the same on a parametric EQ, with the added benefit that you can make the Q very narrow, to avoid thinning out your mix too much. Be sure to preview your audio to make sure you're making it sound better and not too thin.

5. If you're worried about the bottom end of your audio, particularly after cutting a little at 300Hz, you can add some warmth by boosting the bottom end. We rolled off the extreme low end earlier, but those frequencies are generally inaudible on most systems. To add audible bottom end, you need to boost in the 80 – 200Hz region. Where you boost depends on what (or who) you're EQing. The bottom end of male voices is usually around 100Hz; female voices are closer to 200Hz.

On a graphic EQ, you can find and push the frequency you're looking for. You may want to push the frequencies on either side slightly, as well. And the same goes for parametric; find the frequency, choose a fairly wide Q, and boost a bit. Preview your audio.

6. Finally, you need to decide if your audio needs any final sparkle. You can add this by boosting your high frequencies ever so slightly.

On a graphic EQ, start lifting at around 5KHz and boost the frequencies above 3dB. On a parametric EQ, select 5KHz for your shelving frequency and boost 3dB. Preview your audio. If you're happy with the sound, apply it! You may want to save this as a preset if this is a setting you think you'll be able to reuse.

Figures 1a and 1b show the results of all the preceding steps using graphic and parametric EQ. Your results may be slightly different; in fact, they should be, because you're listening to something different!

Figure 1: The results of the step-by-step example, illustrated on a) a graphic EQ and b) a parametric EQ.

Using a graphic and parametric equalizer

2008-04-16T23:41:00.000-07:00

Using a graphic equalizer
Graphic equalizers divide the frequency spectrum into a specific number of bands and assign a fader to each band, as shown in Figure 1. The number of bands varies, depending on the hardware or software. The more bands you have, the narrower the range of frequencies you're affecting when you move a fader up or down.

Figure 1: A typical graphic equalizer (Sony Sound Forge)

Using a graphic equalizer couldn't be easier; you just grab a fader and push it up or down. If you're not sure exactly which frequency you want to work on, don't be afraid to experiment. Grab a fader, push it up, and preview the result. You should be able to hear that frequency being boosted in your file. If you can't hear it, push the fader up even more. Push it up until the frequency is horribly exaggerated. Don't worry; this is how audio engineers do it. Exaggerate to find the frequency, and then scale back the EQ until you've achieved the effect you're after.

This also works when you're looking for a frequency that you want to get rid of. If you can hear a nasty frequency, for example a noisy hiss or even a honking quality to a vocal, hunt for the frequency by boosting until you find the frequency that you're after. Sure, it will make your file sound even worse, but after you find the offensive frequency, you can cut it knowing you're cutting in the right place.

Remember that you want to boost wide and cut narrow. If you're boosting a particular frequency, you should also boost the frequencies on either side — about half the amount you're boosting the target frequency, so you get a nice EQ curve. If you're cutting, cut only the offensive frequency. Don't cut too much; it will make your audio sound hollow and unnatural. If you've ever seen an audio engineer use a graphic EQ, you'll see them adjust their settings to get a nice smooth looking curve, perhaps with one or two nasty frequencies cut.

Using a parametric equalizer
Parametric EQ is slightly different from graphic EQ, because you don't have faders for specific frequencies. Instead, you choose a frequency, how much around your target frequency you want to affect and how much you want to boost or cut. Parametric EQ is usually implemented using knobs, with a separate knob for the frequency, the Q (which is the term used for the width of the effect), and the amount of boost or cut. Some parametric EQ systems don't provide control of the Q; this is known as semi-parametric EQ.

Some parametric EQ also have a little switch that changes the EQ from standard parametric to shelving EQ. Shelving EQ affects all frequencies above or below the frequency setting. Shelving EQ that affects all frequencies below the target frequency is known as high pass, because all frequencies above the target frequency are passed through untouched. Similarly, shelving EQ that affects frequencies about the target frequency is called a low pass shelf, because all the low frequencies are passed.

Tip The EQ knobs on cheaper mixing desks are often fixed-frequency. They're also often shelving, so they're really not precision instruments. If you're going to use the EQ on your mixing desk, use it sparingly. After you've recorded EQ to "tape," it's hard to remove.

Figure 2 shows a software parametric EQ. You can see that it offers four fully parametric controls, along with both high and low pass EQ. Using a parametric EQ is very much like a graphic EQ, with the added ability to adjust the Q. To find the frequency you want, choose a very narrow Q and boost that frequency. Preview your audio, and move the frequency setting back and forth until you hit your target. Next, set your Q (remember: boost wide, cut narrow). Then adjust the boost or cut until your audio sounds the way you want it. If you want to work on another frequency, just use the same approach: Find, set your Q, and apply the right amount of boost or cut.

Figure 2: A software parametric equalizer (Sony Sound Forge)

EQ (Equalization)

2008-04-14T23:36:00.000-07:00

EQ (Equalization)
Equalization, or EQ as it is commonly known, is adjusting the tonal quality of audio by turning up or down certain frequencies. Audio engineers use the terms boost for turning up and cut for turning down. Many of you are probably familiar with EQ via the bass and treble controls on your home or car stereos. In fact, you may have already fiddled with these knobs to adjust the sound; congratulations, you're an audio engineer. Using your ears as a guide, you adjusted the EQ until it sounded right to you. That's exactly what EQing is.

EQ is used for a number of reasons. Sometimes you may need to enhance the tone of your audio by boosting frequencies that make your audio sound more pleasant. You may need to boost these frequencies to make up for a deficiency in your mic or because your voice sounded different one day due to a cold or a late night. On the other hand, you may want to cut frequencies that aren't helping the sound of your audio. This can also be due to a deficiency in your signal chain or to get rid of something unpleasant, like an excessively nasal sound or too much bottom end.

How to use EQ
At the end of the day, it's all about making your audio sound better. You want your podcasts to sound bright and full, not dull and thin. You may notice that the terms used to describe the effects of EQ are very subjective. Audio engineers regularly use terms like "presence," "sparkle," "warmth," and "air." Believe it or not, these terms aren't that subjective; they're actually ways of referring to certain parts of the frequency spectrum — where exactly in the spectrum is subject to debate, but in the next section we provide you with a table of frequency ranges, along with common terms used to describe the frequencies in each range. The first thing to do, however, is to listen to your audio critically and ask yourself a few questions. The following questions start at the bottom of the frequency range, and work up from there, but you can think about them in any order you like:

- Is it "warm" enough? Is there enough low frequency information? Be careful here, because even good studio monitors have a hard time reproducing the lowest audible frequencies.

- What about the midrange? Are the voices clear and understandable? Or is the sound too harsh?

- How about the high frequencies? Does the audio sound dull? Or do you have the opposite problem — too much high frequency information?

If you're unsure about the answer to any of these questions, do what other audio engineers do — use something else as a reference. For example, you could listen to a radio program that is similar to yours, and do what we call an A/B comparison. Listen to the radio program for ten seconds, listening in particular to the low frequencies. Then flip back your podcast, and compare. Does yours have less? More? Flip back and listen to the middle frequencies, and compare. Finally, listen to the high frequencies. This should give you an indication of whether your podcast is up to scratch, and if it isn't, what you may need to add (or cut) to make your podcast sound better. The trick is to find the right frequencies.

What Signal Processing Is

2008-04-12T13:04:00.000-07:00

When we talk about audio signal processing, we are manipulating level one way or another. For example, when we're equalizing (EQing) a file, we're manipulating the level of particular frequencies to change the tonal quality of the audio. When we use compression, we're turning entire sections of the audio signal up or down, depending on the input level. This may not make complete sense until you've heard these two techniques in action, but it's worth remembering that all we're doing is turning things up and down. It really is that simple. The tricky part is knowing what to turn up or down, and when.

One of the great things about working with audio is that we have such amazingly powerful tools. In the next few pages, you'll see just how malleable audio is. You can make things sound better in many ways and without making things sound unnatural. In fact, we're used to hearing processed audio; virtually all broadcast audio, be it radio or television, is fairly heavily processed.

This is why signal processing is important. We expect a certain level of quality from our audio, particularly in the post-CD world. Gone are the days when people walked around with transistor AM radios with cheap mono earpieces. We're used to high-quality, full-spectrum audio. If your podcast doesn't provide this kind of experience, it sends a none-too-subtle cue: amateur. Think about the difference between a big FM radio station sound and the local community college radio. Some of the difference is the type of programming and the on-air talent, but much of it is just plain inferior processing.

Don't let your podcast fall into that category. You absolutely should be producing a program that sounds at least as good as your local radio station. Anything less is just lazy, and your listeners will know it. Let's start with something we've all probably done unwittingly — equalization.

Archiving Your Masters

2008-04-09T16:31:00.000-07:00

As you produce more and more podcasts, you'll notice your hard drive slowly filling up, particularly if you're saving numerous versions of your podcasts (which is highly recommended). At some point, you'll want to archive your files so you can clear out some space on your hard drive. A number of formats are available for your archives:

CD-ROM, DVD-R: CD-ROM or DVD discs are cheap and reliable. However, they are somewhat limited in capacity, and they start to take up lots of space on your shelves as your archives grow.

External Drives: External hard drives have much greater capacities than CD-ROM and DVD. They also have the advantage of speed, because you don't have to burn the disc. However, there is some question as to how long hard drives last — and if you try to prolong their life by not using them, some hard drives can freeze, taking all your data with them.

Tape-based Backup: Several tape-based archival formats are available. These are extremely reliable, but tape-based systems are expensive and often very slow.

As you can see, there is no perfect archival system. Each has its advantages and disadvantages. You'll probably want to start off burning your files to CD-ROM or DVD-R, and then move up to an external drive or tape-based system when the amount of files (and the success of your podcast) justifies it. Just be sure to archive everything, because you never know what uses you'll have for your programming. When the next media distribution mechanism appears, you'll be ready to take advantage of it.

Finally, it's worth mentioning that no archival storage method is immune to fires, floods, or theft. Consider storing copies of your masters in multiple locations. Storing a portable hard drive at work or in a storage space is simple enough. Online storage solutions also are available for that extra bit of security.

Tip Ironically enough, putting your hard drive in the freezer can "unfreeze" it. The theory is that the lowered temperature shrinks the components and the fluids in the sealed bearings inside the hard drive, thereby unlocking the frozen hard drive. This is intended as a last ditch solution, and if it works for you, get your data off as soon as possible and replace the drive. (Please note that the authors haven't tried this, and we can't be held responsible if something goes horribly wrong, okay?)

Editing (Podcast)

2008-04-06T04:52:00.000-07:00

Chances are good that no matter how good you get at producing your podcast, you're still going to want to do some editing. You'll want to remove the countdown from the beginning of your recording, for one thing. And you may have plenty of other reasons to edit. Many podcasters do a quick "top and tail" edit, where they make sure the beginning and end of their podcast sounds right. This is the minimum you should do.

You can completely change the feel of a program by editing the flow of the material. You can make your guests sound better (or worse) with editing. As mentioned in the preceding section, you can also edit the program to include any pick-ups you did. Editing is a very powerful tool in your production arsenal. The following few sections are intended to give you an idea of how editing can be used to improve your podcast.

Editing for convenience
We covered the concept of pick-ups, where you record the intro and outro for the podcast after the actual interview, or perhaps re-record yourself asking questions to your guests, or even cover a topic that you forgot to cover in the body of the program. These pick-ups must be placed into the body of the podcast, where they belong. It's a simple copy-and-paste operation that saves you the hassle of having to do the entire show over again.

Editing for flow
Unless you (and your guests) have a significant amount of broadcast experience, chances are good that sections of your podcast may drag a little. Perhaps the answer to a question got a little longwinded, or it took you three or four attempts to frame a question the way you wanted to ask it. While a certain amount of this keeps the podcast sounding natural, too much of it can make your podcast sound unprofessional and frustrate your audience. If you find a natural place to edit, try taking out some of the extraneous material. For example, consider the following:

"I've been wondering, because you've been doing this for so many years, and, well, we've known each other for what, ten years now? Anyhow, as an observer of Internet trends and how they adapt, where do you see podcasting in five years' time?"

This could probably be cut to, "I've been wondering, where do you see podcasting in five years' time?" or even "Where do you see podcasting in five years' time?" Some of the removed content may have added color, but you really have to ask yourself whether the information is necessary, and whether your audience will be interested in it. In general, less is more, and it's best to edit when things start to wander off course.

Editing for content
Another thing to ask yourself is whether everything you recorded is necessary. You may have asked a few questions that really didn't go anywhere or didn't really yield any significant insights. Remember that your audience is tuning in for a reason, and if you're not staying on topic, you run the risk of losing them. Another thing to consider is how the topics covered in the podcast are related.

For example, you may start off talking about topic A and then realize that folks need to know about topic B to understand topic A. So you talk about topic B for awhile and then go back to topic A. You may consider moving the discussion of topic B before topic A. Of course, this depends on whether the edits are even possible and whether they feel natural. Editing is incredibly powerful, but it can be a double-edged sword. If an edit is noticeable, you're doing more damage than good. You can't always edit things the way you want.

Tip Another reason to do pick-ups is to cover edits. If you need to remove a large section of content, you can hide the edit by asking a question that seemingly joins the two edited sections.

Editing for quality
Most people, particularly if they don't have lots of broadcast experience, tend to insert lots of "ums" and "ahs" in their conversation, often without even realizing it. In fact, you may be surprised to discover your own verbal "tics" the first time you listen to your podcast recording. This is where editing can be incredibly effective, and it can make you and your guests sound much better. Edit out the offending tics, and presto, you'll sound like a professional.

Tip You may want to edit out breaths taken in the middle of sentences. Breath noise can be particularly problematic if you're using compression, because breaths sound louder. The simple solution is to remove the offending breaths. However, sometimes when you remove breath noise, the resulting sentence doesn't quite "flow" right. The solution is to add a small amount of silence where the breath was, so the sentence doesn't sound rushed.

Editing how-to's
Editing is a really simple operation on most audio editing platforms. All you really have to do is highlight the section you want to work on, and then either delete it or copy it so you can paste it somewhere else in your program. One thing that is really important, particularly if you're going to be doing extensive editing, is to save a "raw" version of the original interview. That way, if you somehow mess up the edited version, you always can go back to the original and start from scratch.

In fact, if you're going to be doing lots of editing, you may want to save intermediate versions. For example, the first thing you may do is tidy up the start and end, and remove all the ums and ahs to clean up the podcast. You should save this version, with something in the file name to indicate what stage of the edit you're at. After you've saved this version, you can then do further editing, removing or rearranging sections of your program. Save this as a third and final master of your program. If you decide that you don't like some of the edits, you won't have to start from scratch.

Recording (Podcast)

2008-04-03T09:29:00.000-07:00

After you've got all your gear set up and you've practiced your microphone technique, you're ready to hit the record button and go, right? Wrong. Recording is not something you should rush into. In fact, the more time you take to test, prepare, and practice beforehand, the better your podcast will be. You've seen it in the movies or on television — the rock and roll roadie going from mic to mic saying, "Check-one-two," over and over again. There's a good reason for this. He's checking to make sure:

- The mic works

- The monitoring desk at the side of the stage is receiving signal

- The mixing desk out in front of the house is receiving signal

- A person standing in front of this microphone will hear himself

Luckily, you won't have to check quite as many things, but you really do need to make sure everything is working before you start recording. It's time for your own version of a sound check.

Sound check
Sound check is what you do before you press the record button. It's the last sanity check before you commit to your podcast. Even if you've used your recording setup a hundred times before, you should always do a quick sound check to make sure everything is working as expected. Your mental check list may differ depending on your situation, but essentially you have to check the following:

- All your microphones are working and have enough gain

- Any other audio sources are working and have enough gain

- All the equipment in your audio chain is functioning properly

- Your recording device is getting a good level

- Your aux send levels (such as the send to a telephone hybrid) are good

- The level in the headphones is good (if you're using headphones)

Of course, to test whether a mic is working, someone has to be talking into it. This is where "Check-one-two" comes in. Always set and check levels with the actual talent, so you get the levels right. After all, not everyone is as much of a blowhard as you are. In fact, some of your guests may be downright wallflowers. If so, a common trick to get your talent talking before the interview is to ask them what they had for breakfast. Even if they can't remember, or if they say they don't usually have breakfast, it's usually enough to get them started and serves as an icebreaker for the actual show. Of course, you can ask your talent about anything you like — just get them talking for a few seconds so you can check your levels. After you've checked all your levels and are satisfied that they look good, you're ready to start recording.

The countdown
You need to do two things to start your recording session. First, you have to press the record button. It's actually not unheard of for complete interviews to be done before people realize that they forgot to start recording. Unfortunately, one of your authors knows from experience. Save yourself the embarrassment, and make sure to press the record button.

Next, let the talent know that the recording has actually started, and leave a good spot for you to edit later on. This is where the countdown comes in. After you've pressed the record button, put a little identifier at the start of your file, including the name of your interviewee, and a quick countdown, something like, "Interview with Charles Peterson, talking about Leica cameras, in five… four… three… two… one." Take a deep breath. Introduce your show, your guest, the topic, and you're off and running.

The countdown is important for a couple of reasons. First, leaving a small, silent gap at the beginning of your podcast makes it much easier to edit. A common mistake novices make is to go from the sound check straight into the interview, without even so much as a breath in between. It may feel natural at the time, but you'll find when you're trying to edit to clean up the start of the podcast that it doesn't sound natural when you cut out the sound check chatter. Second, the countdown is a focusing mechanism, both for you as an interviewer and for the talent. It doesn't matter how off-the-cuff you want your podcast to sound; you still want it to sound professional, and giving yourself and your talent that extra few seconds to mentally prepare works wonders.

Tip A great way to test your talent's levels is to have them say their name and then spell it. This way you know how to pronounce their name, and how to spell it!

Intros and outros
Every radio and television interview program with a host has an intro and an outro. They're important, because they tell the audience what they can expect during the program, and they provide an overview of the topic. The intro to your podcast should have a "hook" in it, meaning a sneak peek or hint about the subject matter that makes the show irresistible to your audience. Not everyone in your audience is going to be riveted by every single guest and topic you decide to cover. We live in a busy world, and you've got lots of competition for your audience's time. Use the intro to tell your audience why you're excited about the program, particularly if you're covering a slightly obscure topic or you have a guest without marquee name recognition. If you do a good job of getting your audience excited, they'll stick around for the entire podcast.

Similarly, be sure to wrap up every program with a good outro. Obviously, you need to thank your guest(s) and your audience. You should also summarize the program, highlighting the subjects you covered. Then use this time to talk about your next podcast. If folks have made it this far, chances are good that they'll come back for your next podcast, perhaps even subscribe to your RSS feed. You can help ensure that they do so by letting them know what to expect next time around. This may be the first program that some listeners have tuned in to. Even if you don't know exactly who your guests will be or what topics will be discussed during the next program, you can at least give them an idea of what to expect.

Doing "drop-ins" and "pick-ups"
No matter how prepared you are, you may forget to cover something that you absolutely must have in your program. You may realize it at the end of your recording session when glancing at your notes, or heaven forbid you may realize it during the editing phase. Not to worry; if you were relatively careful setting up your levels, you should be able to do it as a "drop-in" or "pick-up."

A drop-in is when you record over an existing recorded piece and replace a section with a newly recorded version. For example, when movies are sanitized for viewing on airplanes and television, the actors have to drop-in over all the blue language and replace it with "drat!" or some other acceptable utterance. A pick-up is when you add to the end of the recording, knowing that you'll later edit the piece and insert the pick-up section where it belongs in the interview.

Drop-ins are more common in multi-track music recording, where an otherwise perfect performance may be marred by a single bad note. In cases like this, the musician or singer will sing along with the recorded version, and the engineer will "drop in" and record over the offending section. This requires quite a bit of skill and is not for the faint-hearted.

Pick-ups, however, will probably become part and parcel of your podcasting routine. For example, you may want to redo your introduction to reflect something that came up during the interview. Or you may want to rephrase some of the questions you asked, or perhaps even ask a question that you forgot earlier in the interview. In this case, you can simply do a pick-up, where you record what you need after the initial interview. Then, during the editing phase, you can move the sections around at will. Editing is covered in the next section.

Microphone Technique

2008-03-30T11:45:00.000-07:00

It may seem like second nature to some to speak into a microphone. Others may look at the microphone with the same look you'd give a high-tension wire lying on the ground. The fact of the matter is that good microphone technique is important to produce a good podcast. Different mics have different pickup characteristics and different sensitivities, so you must use proper technique to get the best out of your mic.

The basic requirement is that the microphone be in front of the sound source, as close as possible, but not so close that the microphone distorts or picks up any noise, particularly from troublesome consonants such as the letters "p" and "b." These letters are known as plosives and can be quite problematic, because the burst of air that comes out of your mouth when you pronounce them can cause the microphone to "pop." This is audible as a loud pop or a "thunk" in your recording. You may be able to get rid of this noise later on using signal processing, but try to avoid them in the first place.

Plosives are created by letting out a big burst of air from your mouth. The pop occurs because the tiny diaphragm inside the microphone is overloaded. To avoid this, you can use a pop screen, which is a bit of foam or sheer material designed to break up the burst of air. Pop screens must be acoustically transparent, meaning that they should not muffle or distort the sound at all. Many handheld microphones have a pop screen built in, as shown in Figure 1. For other mics, you can buy foam pop screens that fit over the microphone or a pop shield that is placed in front of a microphone. All of these are very effective at reducing the incidence of microphone pops.

Figure 1: A pop screen

Tip In a pinch, you can create your own pop shield by stretching a piece of pantyhose over a coat hanger and placing it in front of your microphone.

Handheld mics
Handheld mics are generally dynamic, directional mics, which means that they are resistant to handling noise, and tend to pick up in one direction. Directional mics must be pointed at the source they're recording. That may seem obvious, but novices sometimes forget they're holding the mic. Their hand will drop to their side, completely oblivious to the microphone. For this reason, handheld mics are often better left to seasoned professionals.

Clip-on mics
Clip-on mics, also known as lavalier mics, are a great option for most podcasting applications. They're small and unobtrusive, so people often forget they're even wearing them. (This can be somewhat embarrassing when a guest or on-air talent attempts to walk away with the microphone still attached.) Clip-on mics come in both directional and omni pickup patterns. For interviewing applications, use omni-directional mics, because they provide better pickup when the person speaking turns his head from side to side. If you're using directional mics, the level can drop dramatically when the talent turns away from the mic. For that reason, microphone placement is important when using clip-on mics.

The placement of a clip-on mic is dependent on the pickup pattern of the microphone, the clothing the talent is wearing, and the placement of guests, as shown in Figure 2. If two people are facing each other, for example sitting across from one another at a table, the mics should ideally be placed centrally, about six inches below the speaker's chin. If two people are sitting side by side, the mics should be placed so that when they are talking the mics will be in the best possible position to pick up the signal.

Figure 2: Clip-on mic placement depends on the situation.

Studio mics
If you have the luxury of a studio setup for your podcasts, you can use high-quality studio microphones. These mics can be used only in studio settings because they are so sensitive. They are very susceptible to handling noise and therefore impractical for handheld or non-studio applications.

Studio mics are placed on mic stands and often in special suspension mounts that make them less sensitive to vibration. The mic should be positioned so that it points at the talent's mouth. Usually, you want to have the mic a little high and pointed slightly downward towards the user's mouth, as opposed to below them and pointing up. This helps prevent pops, because the burst of air tends to be aimed downward.

Many, but not all, studio mics are condenser mics. In fact, two of the most popular radio mics, the Shure SM-7 and the Electrovoice RE-20, are dynamic mics. Both of these mics are treasured because of their lack of proximity effect and their resistance to pops.