[FFmpeg-devel] [PATCH] alac: allow extra data without the ATOM header

Steve Lhomme robux4 at videolabs.io
Mon Feb 15 10:02:01 CET 2016


> Steve Lhomme <robux4 <at> gmail.com> writes:
>
>> can be found in such sample
>> http://streams.videolan.org/issues/16620/VLCSupportsample.mkv
>
> The sample works fine here both with current and
> old FFmpeg.
> I believe it should also work with vlc --demux=ffmpeg

It should because the demuxer has to reconstruct the ATOM data
https://github.com/FFmpeg/FFmpeg/blob/master/libavformat/matroskadec.c#L1981

I implemented the same change in VLC. But I think it would be better
if the decoder works with the lighter version of the extra data.
Especially as in the decoder the first 12 bytes are just skipped.

> Is vlc supposed to remux alac from mkv to mov?

For the moment, yes.

> Does it work? If not, I don't think this patch should
> be applied.
>
> Carl Eugen


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