[FFmpeg-devel] [PATCH 2/2] lavf: Add function for accessing Matroska Codec <-> CodecID table

Reimar Döffinger Reimar.Doeffinger at gmx.de
Wed May 30 21:44:07 CEST 2012

On Wed, May 30, 2012 at 02:53:00PM -0400, Derek Buitenhuis wrote:
> On 30/05/2012 2:47 PM, Reimar Döffinger wrote:
> > You didn't say for what purpose/why that would be useful.
> To enable users to use other demuxers than lavf (such as haali).
> It is currently not possible to do this without this table.

I don't really understand that. Or rather I have a suspicion,
which makes this a bit of a problematic approach, see below.

> For a similar case, see:
> http://ffmpeg.org/doxygen/trunk/group__riff__fourcc.html

The reason for that is that almost every format has a AVI fourcc,
thus it is suitable as a universal identifier to players like
MPlayer that don't want to rely on CODEC_IDs, particularly since
FFmpeg doesn't have one for each codec that exits.
However that only works of course if all demuxers translate to
a fourcc. That is not unreasonable, since all that want to work
with DirectShow or at least VfW have to I think.
The case where you need the mkv values seems to be the case where
the demuxers just throw out container-specific identifiers.
For that case I don't think this approach of one function returning
one array is reasonable, because the only logical conclusion would be
to have one such function for every single container that exists.
So there should a more efficient API then, if it's no longer about
supporting conversion from _one single_ common standard.

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