When we last convened, I discussed options for
encoding video for the Apple TV. A number of readers followed on with questions about how to create the best possible video that would play on both an Apple TV
a 5G iPod—the idea being that it’s easier to encode just the one time and play the result on multiple devices.
In order to do this you must encode for the lowest common denominator, which, in this case, is the 5G iPod. That iPod will accept H.264-encoded files at a resolution of up to 640 x 480, with a maximum bitrate of 1,500kbps, and up to 30fps. That video’s audio track supports AAC-LC with a maximum bitrate of 160Kbps, stereo, and a sample rate up to 48kHz.
Should you wish to encode at a resolution of 320 x 240 (and, if you intend to show the resulting video on your Apple TV, you should put such thoughts out of mind this instant) you’re limited to a maximum bitrate of 768Kbps.
QuickTime Pro 7.1’s Export to iPod option now exports to 640 x 480 or 640 x 360 (depending on the source file’s aspect ratio — 4:3 or 16:9). Apple suggests that if you’re creating content for both the iPod and the Apple TV you not change source files with a 16:9 aspect ratio to a 4:3 ratio when exporting. If you do go to 4:3 the video won’t expand to the edges of a widescreen TV.