[FFmpeg-devel] libavformat/movenc.c problem: only first audio track is enabled

[Aaron Miller]

Hi all,

After upgrading to FFmpeg 0.10, I discovered that it writes QuickTime files
with only the first audio track enabled, unlike the version I used from
mid-2011.  According to the flags in 'tkhd' atoms, all these tracks should
be enabled, but with Mac QuickTime Player Pro 7.6.6, these flags are
apparently ignored in this case.  It turns out that the Alternate Group
fields of 'tkhd' atoms is the problem: they are set to 1 for the audio
tracks and 0 for the video track.  In the version of FFmpeg I was using
before, it is 0 for all tracks.

I see that the behavior of FFmpeg was changed in this commit from September:

http://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=9a9ceb8776264c799ff9669ed7e287a5daaab564

specifically:
    http://bit.ly/JrI23W

Is there a reason this change was made?

Thanks,

Aaron Miller