[XviD-devel] GMC rc2

Christoph Lampert xvid-devel@xvid.org
Sun, 12 Jan 2003 12:12:54 +0100 (CET)


On Sun, 12 Jan 2003, Dirk Knop wrote:

> Hi,
> 
> Christoph Lampert wrote:
> 
> >QPel + GMC is fixed, please test everything in ASP (QPel, Bframes, GMC). 
> >
> >There is no support for interlace (yet) or reduced res (ever). 
> >
> 
> Ok, did a first test on "Das Boot". According to sysKin I modified line 
> 1764 in encoder.c to have a "better" gmc/no-gmc decision (in terms of 
> filesize). Changed it to
> 
> if (iSAD + 12 <= pMB->sad16) {        /* mode decision GMC */
> 
> Used features:
> - GMC
> - QPel
> - bframes 3/150/100
> 
> libavcodec/ffdshow (from 13.12.2002)  doesn't decode the resulting video 
> correctly, it smears MBs through the image (looks funny though). 

Okay, XVID is fixed to use correct rounding for average motion vector (as
microsoft reference does). 

ffmpeg has to be changed for this ( it's only a 1 line fix in h263.c 

instead of 

        sum /= 256;
        sum= RSHIFT(sum<<s->quarter_sample, a);

it should be 

        sum= RSHIFT(sum<<s->quarter_sample, a+8);

or maybe it doesn't matter... because now suddenly here it works
without?!?

Anyway, please continue testing!

gruel