[XviD-devel] qpel chroma rounding

[Michael Niedermayer]

Hi

On Wednesday 30 October 2002 19:38, Michael Militzer wrote:
> Hi all,
>
> I just commited the fixed qpel chroma rounding code. I believe that XVID's
> qpel motion compensation code is now (finally) correct (at least fdam seems
> to like it). However I'm afraid that maybe no other decoder might be able
> to decode XVID qpel content correctly at the moment. DivX 5.0.2 decodes the
> chroma blocks incorrectly (but also luma is wrong if 4MV is used, so DivX5
> is no good choice anyway). I haven't checked ffmpeg, but I think I remember
> that the rounding is done in a different way here too, so a patch might be
> needed...
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
[...]

Michael