[Matroska-devel] Re: [Ffmpeg-devel] Adding matroska support to FFMPEG via libmatroska/libebml, in C++ ?

Alexander Noé alexander.noe at s2001.tu-chemnitz.de
Tue Oct 14 16:00:01 CEST 2003


Steve Lhomme wrote:

> 2) This is only for specific audio codecs that have internal framing. 
> I'm 90% sure any hardware/software player that can decode these will 
> have no problem being fed with multiple frames at once. I know this is 
> the case for MP3 at least. And as, so far, we are the ones who define 
> how each codec should interpret data out of a Block. We can change it 
> easily and that will be the standard way in matroska. And that won't 
> prevent anyone from using 1frame=1block. So I see no real 
> compatibility problem here. 

Some hardware decoders HAVE to be fed with 2 AC3 frames at once. Mosu 
said that
the AC3 filters should be made take care of b0rked hardware.

 > 1) Alex's test shows that we do have the smaller overhead. (that was 
not obivous
 > to him before).

It was. But it is a hack, and I did wait for your permission to hack 
matroska. If
you had said before that I can hack it, I would have done it...

 > So now he cannot claim anymore than AVI can > beat MKV. (of course
 > there are probably cases where it would, but not in 90% of cases)

The AVI overhead is constant at 16 bytes per chunk. Matroska has 13 for
a p-frame and 16 for a b-frame. So with video-only, it is impossible.

If you allow the same frame grouping for audio frames in Matroska as for 
AVI, I
would not see any possibility to get the AVI overhead below the Matroska 
overhead.


Alex




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