[Matroska-devel] Re: WavPack in Matroska

Steve Lhomme steve.lhomme at free.fr
Sun Jul 4 12:14:06 CEST 2004

Paul Bryson a écrit :

> "Steve Lhomme" wrote...
>>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.
> This element already exists on the Video side.
> http://matroska.commo.de/technical/specs/index.html#TrackOverlay
> Adding it to the audio side of things seems like a pretty small task.  As far as
> DirectShow goes, it shouldn't be hard to create two pins from the splitter, one
> for the lossy data, and one for the correction data.  Then the decoder has two
> input pins, one for each.  If there is only the lossy pin connected, then it
> decodes lossy.  If both are connected, then it decodes both.  This makes it
> necessary to create a seperate CodecID for the correction data.  Maybe somthing

OK, very good point. It already exists in the current format and would 
fit perfectly what we need. So there's no need adding an element elsewhere.

The downsides I can see are :
- a bit more overhead
- would need a clean muxing of both tracks, ie the related blocks should 
always be close to each other

But these are minor problem...

For stripping the complement, we would need an option in mkvmerge like 
--strip-overlays or --strip-overlay "CodecID" (just ideas).

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

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