DISCLAIMER: I have not tried this and it may have been posted already. This is from a friend of mine with a Mac who wanted me to post this. I started with a movie, which was originally an MKV file (720P). I ran it through Visual Hub at very high settings to preserve picture quality, then tagged it with MetaX. At the time, this was the best you could do for Apple TV (DPL II sound). I then ripped the AC3 audio from the DVD Opened my already tagged MP4 file in QuickTime Pro Opened the AC3 audio in QuickTime Pro I noticed they weren't the exact same length, which can cause sync problems. Therefore, I trimmed the movie to match the audio in length. Selected all audio and copied to clipboard Selected all movie and pasted the audio into the movie Saved as self-contained .mov file Moved into iTunes iTunes recognizes the movie as having stereo sound and plays it fine. Apple TV recognizes it as DD5.1 and plays it fine with no audio sync problems The best part of all - it still has the tags from when I first made it an .mp4 file.