[XviD-devel] qpel chroma rounding

[Michael Niedermayer]

Hi

On Thursday 31 October 2002 00:31, Michael Militzer wrote:
[...]
> > iam not sure if
> > mx = (motion_x >> 2) + roundtab_78[motion_x & 0x7];
> > is correct
> >
> > at least a1ge2_ace_L3.bits looks wrong if i use it for the x part of the
> > MV
> > but that one is interlaced, i dont see any difference in the few
> > non-interlaced qpel test-streams i found :(
> >
> > could u point me to the part of the M$ reference which uses the
> > roundtab_78
>
> ok, I think you are right: we have to half the vector in a first step and
> then round using table 7-9 afterwards (the whole rounding process becomes
> much more logical this way...). I've updated the dev-api-3 tree again, you
> may have a look and tell whether you can agree now or not...
seems ffmpeg & xvid use the same rounding now :)

[...]

Michael