Showing posts with label QuickTime. Show all posts
Showing posts with label QuickTime. Show all posts

Feb 28, 2009

RSS: Podcasting's Secret Sauce

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.

Feb 2, 2009

Encoding H.264 video using QuickTime Pro

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.

Nov 11, 2008

Other Encoding Formats | Podcast

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).
  • Oct 7, 2008

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

    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.