[XviD-devel] Decoder performance

[Christoph Lampert]

On Fri, 8 Aug 2003, Edouard Gomez wrote:

> Michael Militzer (michael at xvid.org) wrote:
> > which encoding features are used for this 'matrix-trailer.avi'? Qpel,
> > bframes? Or just simple profile only?
> 
> I used:
> XVID_OPTIONS="stats:max_bframes=1:trellis:chromame"
> defaults:h263, motion=6, vhq=0, hqacpred
> 
> So it just differs from SP by the usage of bframes.

Did you check speed without bframes? It seems to me that ffmpeg is very
fast with bframes, and I can't remember that Xvid was optimized or even 
tested for that... 

Can you compare against a benchmark file from mplayer ftp so others can
check, too?

e.g. 
ftp.mplayerhq.hu:/MPlayer/samples/V-codecs/DX50-DivX5/test.no-b-frames.divx5.avi
ftp.mplayerhq.hu:/MPlayer/samples/V-codecs/DX50-DivX5/test.b-frames.divx5.avi

If I extract MPEG-4 from those with mplayer -dumpvideo, I get 124 fps
(no-b) resp. 92 fps (with b) for those with 

./xvid_decraw -w 624 -h 350 -i b.m4v  -asm | grep fps
./xvid_decraw -w 624 -h 350 -i nob.m4v -asm | grep fps

Seems that XVID decodes bframes much slower than non-bframes. 



But with mplayer/ffmpeg decoding the AVI I get

168fps for no-bframes      
183fps(!) for b-frames 
 
so ffmpeg decodes bframes _faster_ than no-Bframes! No wonder that for the 
bframes clip, ffmpeg is twice as fast as XVID... 

gruel