By and large (not counting hacks) video formats, readable apple set-top box only 2: H.264 (AVC) Main profile and MPEG-4 Simple profile. And it is not the same as "MPEG-4", which is used DivX / XviD, are not, actually, "right» MPEG-4 codec, and a primitive version with the appropriate level of quality. And H.264 features are implemented, not all.
With sound even easier. Here, of course, MP3, favorite Apple AAC, Apple Loseless (audiophiles, hello!) Plus uncompressed AIFF / WAV. The five-channel Dolby Digital aka AC3 is supported only as a Pass-through. FLAC / DTS / Vorbis and others like them are in flight.
Apple is unlikely to be a problem to support multi-channel sound in the future (in AAC format with this everything is fine, you can to store at least a dozen discrete channels), except that the current generation of Apple TV only two analog channel exit. Do you want more - get connected to the receiver optics (which is a few hundred rubles green).
Transcode video to display on the Apple TV is easy. In Handbrake, for example, there is a good Apple TV preset with a bit rate sufficient for dual-layer DVD drive (odnosloyki usually possess not very high-quality images of themselves), having at least one flaw in the measure lousy AAC codec FAAC. Can be carried out through conversion and QuickTime Pro or analogs, but at the same time instead of the orderly and high quality x264 have to put the brakes H.264 codec Apple. The QuickTime, though not able to encode the DVD, but Handbrake does not follow the resolution and betreytom... no perfection in the world. Although the problem may only occur when working with HD content.
If Apple TV «pohachen", you can try to mount a network share or USB drive with movies and using NitoTV see them. View thus be able to almost anything... The trick with the wrapping film in the MOV container, or the creation of links in iTunes, works well on the Mac does not work here: Apple TV refuses to synchronize with similar files.
If you mess in your library, you can try to instruct search and record tag any kind of automated softiny SongGenie.
Elgato eyeTV It allows you to convert after recording TV shows to Apple TV compatible format. True. for Russian television he would clearly overkill, reasonable use, for example, ipod preset.
In the presence of high-quality and low-cost Internet connections bunch of content can be found in the iTunes Music Store.