[Matroska-devel] WavPack in Matroska

Steve Lhomme steve.lhomme at free.fr
Sat Jul 3 15:37:42 CEST 2004


Steve Lhomme a écrit :

> The idea is that it should be stored as if it was a basic lossless file 
> (ie both in the same file). And when needed you can only keep the lossy 
> part only in another file (like peeling for Vorbis).
> 
> Which leads to another problem. If we store all the data in the same 
> track (see previous email) we have to have a codec interaction when we 
> want to create a lossy-only version of the file. So it might be a good 
> idea to have it at the container level instead... I couldn't imagine a 
> clean DShow graph if it was at the codec level, but it's easy on the 
> container level.

IMO, we should add a new element for such a case. It's not a 
CodecPrivate data for each frame, but rather a secondary stream that 
makes sense only with the first one... So we have 2 choices :

- add a track property to state that the track is not to be played and 
correspond to data for track XYZ. IMO that's not very clean and not 
backward compatible.

- add a new element to the BlockGroup with a SecondaryData item. That's 
clean. But it only makes sense if the complementary data in WavPack is 
on a frame/block basis. David ??? This way it would be easy to have an 
option in mkvmerge like --strip-secondary to get only the lossy part of 
a content (could apply to other things too). If we go this way, we 
should investigate a bit more if it could be generalised to more 
content/codec/features.

-- 
robUx4 on blog <http://robux4.blogspot.com/>



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