MKVTools and ATV2

Discussion in 'Apple TV and Home Theater' started by ninethirty, Jan 10, 2011.

  1. macrumors 6502a

    Joined:
    Mar 1, 2006
    #1
    I posted the other day about some issues I was having with MKVTools and the audio not syncing up correctly in converted files, but now I'm really having issues. I was watching a short 30 minute TV show this morning that I converted from MKV (Video was H.264 and Audio was 6 Channel AC3 - I set both to pass through) and the audio was way off. I noticed that if I paused the movie and started it again, the audio would sync up, but went off again quickly.

    Anyone else having this problem? Is there a better program for this kind of conversion.. or are there settings I'm not using properly?

    Thanks in advance!
     
  2. macrumors 65816

    Joined:
    Jan 13, 2008
    #2
    If it's already H.264/AC3 that you want to pass-through, you can remux it using Subler instead.
     
  3. macrumors member

    Joined:
    Jul 7, 2008
    #3
    I've run into some files that at times drift in and out of sync with my ATV2. When I play these files on the computer, they play fine. It's important to remember that MKVtools can save substantial processing time by not re-encoding the video, and instead setting a flag that tricks the ATV into playing videos that are often out of spec with what the ATV wants. This usually works fine, especially for devices like the PS3. The ATV seems to be a little more touchy though. I've even noticed and heard of sync issues with netflix videos and rented videos, so perhaps there is some ATV issue that needs to be worked out. I don't know. Usually, re-encoding the video and/or the audio fixes the issue. MKVtools will allow you to do that if you look in the mp4 tab, or you can use a program like handbrake. I don't believe that subler uses mp4box for muxing like MKVtools does, so that would also be a good option to try. If the sync is way off, it may be that the frame rate is off. Changing it to one of the other standard frame rates will often fix this problem.
     
  4. macrumors 65816

    Joined:
    Jan 13, 2008
    #4
    This is the most common culprit for me. (In general; not specific to ATV.)
     
  5. thread starter macrumors 6502a

    Joined:
    Mar 1, 2006
    #5
    Is it that the file itself is mis-reporting the frame rate, or that MKVTools messes it up? Would the best solution be to open the MKV in Quicktime or VLC, find the framerate and then make sure you're using that in MKVTools?

    Cheers!

     
  6. macrumors member

    Joined:
    Jul 7, 2008
    #6
    MKVtools is using the frame rate reported to it by mediaInfo, which more than likely is the same as what VLC and quicktime would report, though it couldn't hurt to give them a try :). Unfortunately, there have been so many other things on the to do list above this, that I've yet to look in depth into possible fixes for this.
     
  7. macrumors 65816

    Joined:
    Jan 13, 2008
    #7
    If it's indeed the framerate rather than another issue, then the audio will grow more out of sync further into the video. If that's not true of your sync issue, it's something else, so don't worry about fps.

    If that is true, though, I'd try opening it in MKVTools, Quicktime, and VLC and cross-checking the fps. Last time it happened to me, VLC gave the correct fps, and Quicktime gave me the wrong one. I don't remember what MKVTools reported.
     

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