[FFmpeg-devel] Question regarding seemingly superfluous fourcc checks

[Mats Peterson]

On 01/07/2016 10:32 AM, Mats Peterson wrote:
> Are the following kludges for A_QUICKTIME and V_QUICKTIME ways to
> accommodate old broken Matroska files that FFmpeg wrote in the past? I'm
> asking because in normal cases, the fourcc in A_QUICKTIME and
> V_QUICKTIME always starts at offset 4, without exception.
>
> A_QUICKTIME:
>
> if (ff_codec_get_id(ff_codec_movaudio_tags,
> AV_RL32(track->codec_priv.data))) {
>      fourcc = AV_RL32(track->codec_priv.data);
>      codec_id = ff_codec_get_id(ff_codec_movaudio_tags, fourcc);
> }
>
> V_QUICKTIME:
>
> if (ff_codec_get_id(ff_codec_movvideo_tags,
> AV_RL32(track->codec_priv.data))) {
>      fourcc = AV_RL32(track->codec_priv.data);
>      codec_id = ff_codec_get_id(ff_codec_movvideo_tags, fourcc);
> }
>
> Mats
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I should add that it concerns libavformat/matroskadec.c.

Mats