Multi-format encoding

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.