[XviD-devel] GMC ?

[Christoph Lampert]

On Wed, 7 Aug 2002, Dirk Knop wrote:

> Hi,
> 
> Marc FD wrote:
> 
> > Is GMC implemented in XviD ??
> 
> Noope.
> 
> > (if not) Would GMC be implemented a day in XviD ?
> 
> I think so. But I've seen noone coding this stuff yet ;) since the 
> effect is too small if I remember correctly.

As far as I knowm it depends very much on the material. DivX5's  GMC
is surely not very effective. 

But it's on my list of "TODO's". I looked into literature a little. GMC
can be done, and it can be done fast (realtime), but since we haven't
started, yet, I will take quite a while.

> > PS : just need a confirmation from a MPEG-4 "expert".
> > Can Wavelet compression really be used instead of DCT ??
> > i readed somewhere that MPEG-4 was using wavelets ??
> > i think we were using f/i DCT. what's true ??
> 
> Wavelet can be used, but someone already wrote earlier that wavelets 
> aren't in SIMPLE or ADVANCED SIMPLE mpeg4 profiles and thus it's of no 
> use. I too would like to watch an encoding using  wavelet instead of 
> DCT, just to see if it can keep up with what it promises ;) (or is DCT 
> "non destructive" as well and can be lossless transformed, too? I just 
> thought that I read something about that in an older c't...)

MPEG-4 has a (small) section about wavelets, but not for video, only for
still images/textures. 
For video, wavelets still have too many problems. They may be useful for
very low bitrates (ISDN telephone) one day, but don't expect XviD to adopt
this. 

gruel


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