[XviD-devel] bframes and qpel

[Radek 'sysKin' Czyz]

Hi everyone,

I already started implementing qpel support to bframes. Is anyone
working on it? If not, don't start :>

I have motion estimation for forward, backward and interpolate search
ready. I'll make motion compensation soon. Also direct search
shouldn't be a problem, all I'll have to do is discover a method to
move a dimond in non-qpel positions, because it's going to be
incredibly slow otherwise.
Btw, the entire thing is, of course, very slow. I'll experiment on
using sad-bi to do the checks, instead of performing interpolation to
temporary memory first.
If someone is interested in writing some asm, I'll recommend:
 - sad8bi2/sad16bi2 with different rounding then current (I don't know
how important it is)
 - 16x16 halfpel interpolation for halfpel positions in forward and
backward search (and interpolate?). If you remember, interpolation
should _not_ be done on 8x8 blocks in this case. You might combine it
with 8to16sub for speed.
 -  8x8 SAD which accepts FOUR sources - hv-interpolation combined with
sad. Will also be used for faster chroma ME. Correct rounding would be
nice.

Well, only 16x16 hpel FIR filter is really needed, all other stuff I
can do in several steps... It will only be slow.

OK, that would be it. Ah, one more thing: is there _again_ something
wrong with chroma channels in qpel encoding? not shift this time, but
colors get... strange in ffdshow. mostly visible at keyframes, when
they suddenly go correct again. I use this new, 3 days old ffdshow.


Best regards,
Radek