[MPlayer-users] Re: Mpeg2 encoding results

Jonathan Rogers jonner at teegra.net
Wed Sep 3 09:23:29 CEST 2003

Nico wrote:
> First a premise: I don't consider this comparison a  competition between 
> xvid and lavc (which would also be unfair, since xvid compresses more 
> that lavc's mpeg2), but only
> a chance to show what I consider imperfections in the current lavc's 
> outcome, so please let's avoid
> flames. .

MPlayer uses lavc and XviD just as well, so flames would indeed be 
silly. I could imagine heated discusssions on the ffmpeg and XviD lists, 
but here, there shouldn't be too much bias. I'm interested in how to get 
the best quality encodings for a given bitrate, so fair comparisons are 
always good. Hopefully, that should be the general sentiment.

I've struggled with the problem of grey blocks. In particular, I encoded 
"Enemy at the Gates," which has lots of dark grey and brown tones. Even 
using a target size of 1600MiB (0.26 bpp), I wasn't able to get rid of 
the visible grey blocks, especially in cloudy shots (I know, that's an 
even bigger problem). I encoded one scene about six times with different 
lavc options as well as XviD, but it never improved much. The blocking 
looked a little different when encoded with XviD, but not appreciably 
better. I got the impression that the encoders weren't effectively 
dealing with the fact that the average brightness of the frames was 
lower than a typical movie. Maybe the brightness model of the encoders 
is more absolute than human vision.

Jonathan Rogers

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