[FFmpeg-devel] [PATCH] attachments support in matroska demuxer

Måns Rullgård mans
Sun Jan 20 14:40:00 CET 2008

Reimar D?ffinger <Reimar.Doeffinger at stud.uni-karlsruhe.de> writes:

> Hello,
> On Sun, Jan 20, 2008 at 03:42:09AM +0100, Michael Niedermayer wrote:
> [...]
>> > > iam against some undocumented char *type
>> > > please document precissely what it repressents and how it differs from
>> > > codec_tag, stream_codec_tag and codec_id
>> > > or even better get rid of it and use codec_tag or explain why the type
>> > > here should be special cased relative to these funny codec id strings in
>> > > matroska
>> > 
>> > Currently, *type stores the standard mime type of the attachment.
>> so it idetifies what the attachment is ...
>> thats what codec_tag does alraedy ...
> Sorry to be so flameish, but no, maybe codec_id does that, but codec_tag
> certainly does not. E.g. for mp4 files all kind of audio has mp4a as
> codec_tag and some other things like that.

Still after years of working on FFmpeg, I have yet to figure out the
purpose of codec_tag.  In my own apps using lav*, I have never read
nor set it, and everything has always worked just fine without it.

I would certainly not consider using codec_tag a proper substitute for
a MIME type field.  There of course the issue of MIME types not having
complete coverage, but that's beside the point.

M?ns Rullg?rd
mans at mansr.com

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