[gst-devel] thoughts on extradata

[Jérémy Simon]

Hi,

> I don't know what it is. For MPEG audio, it's ususally only a few (2)
> bytes. I think this carries channel location information (so left-front,
> right-front, bass, right-rear, left-rear, center, ...) and
> samplerate/channelnum. Don't know for sure. I've looked it up in the
> faad sources some day, but forgot... For MPEG-4, it's 32 byte of total
> randomness. Probably some important (quantization or so) table, because
> the MPEG-4 video decoder in ffmpeg fails horribly without it. I don't
> know for sure. SVQ3 just has flags, WMA has flags1 and flags2, both
> guint32... I guess that's when it starts to become binary: I don't know
> what these flags *mean*.

For example, ffmpeg people just changed the SVQ3 metadata handling :( So
we'll have to make some changes to qtdemux. The svq3 plugin expect the
qt 'stsd' atom as extradata. Putting this into a *special* buffer is
propably the easiest solution and we would handle codecs that need a
palette from the demuxer like huffyuv.
  
--
Jeremy