[XviD-devel] DivX5.03 rounding?

Christoph Lampert chl at math.uni-bonn.de
Thu Feb 6 14:34:15 CET 2003


On Tue, 4 Feb 2003, suxen_drol wrote:

> 
> On Mon, 03 Feb 2003 12:54:36 +1100 suxen_drol <suxen_drol at hotmail.com> wrote:
> > yes it is now compatibile. by default divx503 uses the correct rounding,
> > but if it detects the bitstream was encoded with < divx503, it will use
> > the incorrect rounding (so older streams appear correct).
> 
> wait:
> * divx503 rounds incorrectly when using qpel+bframes.
> * but, qpel by itself appears corect.

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. 

The same questions came up on mpeg4-technotes (without answer). 

gruel 




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