[Matroska-devel] JPEG 2000 codec support

Antonin Descampe antonin.descampe at uclouvain.be
Wed Feb 11 11:54:57 CET 2015


Hi Mosu,

Many thanks for your answer. 

> Le 7 févr. 2015 à 09:28, Moritz Bunkus <moritz at bunkus.org> a écrit :
> 
<…>
> 
>> * What would be the steps to follow to get this codec supported by
>>  Matroska ?
> 
> There are roughly three areas that would need work:
> 
> 1. Define a codec mapping similar to the ones on [1]. I guess that JPEG
>   2000 would be a codec that wouldn't need any initialization data,
>   therefore there would be no CodecPrivate element. All we'd need would
>   be a CodecID; V_JPEG2000 would be the obvious choice here.

ok. Could you point me where the current codec mappings are defined ? 
And what would be the best way to suggest a code modification ? A github pull request ?

> 
> 2. Adopt one of the existing Matroska muxers to produce such files. For
>   mkvmerge this would be quite some work to be done properly as I guess
>   that JPEG 2000 would mean having to read one file per video frame –
>   and mkvmerge currently doesn't support reading multiple file for
>   inclusion in a single track at all. This would have to play well with
>   its GUI (mmg) as well. Support for extraction via mkvextract would
>   have to be added as well.
> 
>   Another choice might be ffmpeg as I seem to remember that it can read
>   multiple files and encode them as a video track already. I don't know
>   how much work it would be to modify it as I have little knowledge
>   about its internals, though.

Ok, I’ll investigate the ffmpeg path as it can indeed already take multiple files to encode them in one track.

> 
> 3. Add support in players. This could be as simple as adding two lines
>   of source code mapping Matroska's new CodecID to the decoder
>   definition for the JPEG 2000 codec (often a FourCC or one of
>   libavformat's #defines/enums), but it might need more work.

Ok, thanks.

Kind regards,

Antonin

> 
> Kind regards,
> mosu
> 
> [1]  http://www.matroska.org/technical/specs/codecid/index.html



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