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

Michael Niedermayer michaelni at gmx.at
Tue Apr 24 16:19:16 CEST 2012

On Mon, Apr 23, 2012 at 04:01:34PM -0700, Aaron Miller wrote:
> 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

thats a merge, the commit which introduced this bug is
commit 7574cacbd5343bc303ee8333956274716e2444d5

> Is there a reason this change was made?

Users wanted to be able to select which audio track is playd in files
containing multiple (in different languages for example)

A proposed fix is in:
[FFmpeg-devel] [PATCH] movenc: set alternative group for alternative streams

If you can test this patch and it works then i can apply it

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Those who are too smart to engage in politics are punished by being
governed by those who are dumber. -- Plato 
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