[FFmpeg-devel] [PATCH] Decode codec private in mkv demuxer

Evgeniy Stepanov eugeni.stepanov
Thu Jun 19 22:43:34 CEST 2008

On Friday 20 June 2008 00:02:41 Aurelien Jacobs wrote:
> Evgeniy Stepanov wrote:
> > Hi,
> >
> > codec private data of a Matroska track can require decoding, depending on
> > the value of ContentEncodingScope element. The current mkv demuxer only
> > decodes frame contents, but not private data.
> OK. Now, can you provide some samples requiring extradata decoding ?
> What tool can generate them ?

You can get a sample here: http://rut.org/mplayer/
Mkvinfo shows "Haali DirectShow Matroska Muxer" as muxing 

> > The first patch moves buffer decoding code to a separate function. The
> > second patch uses it to decode track private data.
> Patches are mostly good, but may benefit from some improvements.
> For example, I think that COMP_HEADERSTRIP have no sens in regards to
> extradata. This kind of "compression" just avoid duplication of redundant
> leading bytes. But extradata only appears once, so there are no possible
> duplication to avoid.

Specs don't say anything about this, so I assume it's possible. For example, 
it could be applied to both extradata and data packets with 
ContentEncodingScope = 3.

> Anyway, I will have a deeper look at the patches later (and I would like to
> be able to test them before commit).

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