[NO-SPAM] [MPlayer-dev-eng] Re: Flaming NUT

[D Richard Felker III]

On Tue, May 04, 2004 at 11:19:14PM +0200, Tristan Seligmann wrote:
> On Tue, May 04, 2004 at 15:36:45 -0400, D Richard Felker III wrote:
> > DivX3, and even the "progressive" groups only use DivX5 or
> > occasionally XviD, never libavcodec's mpeg4 (which is a good bit
> > better)... I'm not saying it's a lost cause, but it'll take a long
> 
> I'd be interested to hear your reasons for saying that lavc's mpeg4 is
> better than XviD. One or two people think that XviD's output looks
> better than lavc's at the same bitrate (with all the applicable
> enhancements enabled), so an informed comparison of the two would be
> nice :)

My comparisons are entirely subjective (no PSNR figures handy), but
lavc tends to produce blocking artifacts when it's starved for bits
(increasing the quantization and quantizing "correctly") while Xvid
and Divx produce what I call a "mudding" artifact instead, where areas
of low contrast swim around like a pool of mud. My guess is that this
corresponds to _not_ increasing the quantizer, but instead encoding
macroblocks with motion vectors only (no DCT), or leaving out some
coefficients after doing the DCT.

It's largely a subjective matter which one looks worse, but from my
experience postprocessing seems to be able to repair blocking quite
well, but not do much for mudding.

Rich