[MPlayer-dev-eng] XviD

[Michael Niedermayer]

Hi

On Thursday 07 March 2002 14:50, Michael Niedermayer wrote:
[...]
> ok, so heres the list (ill post it to the xvid forum in a minute)
> mostly according to the mpeg4 header ... (only new features)
>
> 1. quarter sample mc
> 2. lots of s(gmc)-vop instead of p-vop
> but thes seem to only support a tiny subset of gmc ... nah i didnt expect
> them to do per pixel mc anyway ;)
> all s-vops i saw did had 2 sprite-warping points but the second one was
> allways (0,0) so the gmc does only shift the image (if i understand the
> mpeg4 equations correctly) but according to the warping accuracy they do
> need 1/16 pel mc (iam not sure if this is supposed to be bilinearly
> interpolated or lowpass filtered like 1/4 pel, but imho its not lowpassed)
> the bitstream part is allready decoded in ffmpeg cvs ...
> 2b. a marker bit is missing after the x vector for the sprite trajectory
> 2c. the mpeg4 std has a typo in the definition of W' and H' it says they
> are of the form 2*alpha and 2*beta but imho they should be 2^alpha & 2^beta
> 3. b-vop
> they seem to have a variable number of b-vops between s-vops (iirc i saw a
> much as 7 b-vops between s-vops
          ^^^^^^^
forget that ;)
i cant count, the max i saw where 1B between P r S VOPs but i forgot the put 
a printf() for the P-VOPs ;)

[...]

Michael