If you are having issues with the audio playback of your Apple TV I would suggest going through the steps in this article to troubleshoot -
Thanks for using Apple Support Communities.
Thank you Brett,
I followed the instrcutions to the "T" and also adjusted to 16 bit audio. Still, my generation 3 Apple TV lost audio after exactly 31 minutes. I stopped the movie and restarted with success. The movies are playing via my IMac (1 year old). Interestingly the movies lose audio exactly every 31 minutes it seems and only if I play via IMac. I can play from any other source including airplay, no problem.
Realy appreciate your help!
I have a similar issue. I have a bunch of x264/ac3 files converted to aac (only the audio part is converted) and the audio stops sometimes at 7 minutes, sometimes ~30. It happens in the same interval when the file is played (every 7 minutes or every 30 minutes). I tried converting them with different ffmpeg-settings and it's always the same (I tried using a different encoder: libfaac, aac and libfdk_aac; tried different bitrates for the audio part (constant and variable); tried to convert without subtitles, without metatags, etc.). Essentially I tried everything with those files and the only solution I found so far is converting them with HandBrake which actually is no option because of the reencode of the video-part and therefore taking like forever to complete (I have about 100 of those files).
Any more ideas why this could happen? I tried the solution provided, but it's not a general issue.