[XviD-devel] DivX5.03 rounding?

[Christoph Lampert]

On Fri, 7 Feb 2003, Radek Czyz wrote:

> Hello Christoph,
> 
> > Are we sure that XVID does correct direct mode Qpel? I may have asked
> > earlier, but I remember something that direct mode always uses 8x8 blocks,
> > not 16x16 as we do, even if collocated block is INTER, not INTER4V.
> > For halfpel this doesn't matter, but for qpel it does.
> 
> That's OK, we do it in 8x8 as well. MODE_DIRECT_NO4V is not set in
> qpel mode, so motion compensation to be performed on 8x8 blocks.

Ahhh... that's tricky! Of course I just read the "switch" and thought 
DIRECT_NO4V was set. 

Is decoder doing this as well? There is a call in bf_interpolate_mbinter()

if(dec->quarterpel) {
                if((pMB->mode == MODE_INTER || pMB->mode == MODE_INTER_Q))
                        interpolate16x16_quarterpel(dec->cur.y,forwar...)
                else {
                        interpolate8x8_quarterpel(...)
                        interpolate8x8_quarterpel(...)
                        ...
                }


gruel