[Matroska-devel] audio async when muxing MP4 files into MKV with mkvtoolnix 2.0.2

Richard S. teetrinker at gmx.de
Sat Feb 24 23:40:29 CET 2007

Christian HJ Wiesner wrote:
> Hi Mosu, hi all,
> i am converting MPEG captures from satellite into MP4 files, using VLC
> 0.86a. Both the MPEG and the MP4 file are perfectly in sync. However,
> the final MKV, after being muxed from the MP4 with latest mkvtoolnix,
> will be async. I am not setting any time delays for the audio track,
> so i wonder why this is ?
> The delay i have to use to get it into sync is between -200 to -1400
> ms for the audio track, meaning the audio is normally too late after
> muxing. Here the warning that mmg is giving me during muxing :
> ''CTTS' atom is needed for getting the timecodes right. As it is
> missing the timecodes for this track might be wrong. You should watch
> the resulting file and make sure that it looks like you expected it to.'
> Is there aynthing i can do to avoid this ? Maybe this is a problem of
> x264 or the MP4 muxer used in VLC ?
If I remember right, the MP4 muxer from VLC doesn't work proper if 
B-Frames are used.


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