[Ffmpeg-cvslog] CVS: ffmpeg/libavcodec motion_est.c,1.115,1.116

[Michael Niedermayer]

Hi

On Wed, Dec 28, 2005 at 12:35:09PM -0800, Corey Hickey wrote:
> Michael Niedermayer CVS wrote:
> > Update of /cvsroot/ffmpeg/ffmpeg/libavcodec
> > In directory mail:/var2/tmp/cvs-serv19133
> > 
> > Modified Files:
> > 	motion_est.c 
> > Log Message:
> > hmm did i mess the scaling of these up at some point?
> > anyway, this change decreases bitrate and increase PSNR by ~1.00 on my test file, other files also benefit significantly
> 
> I tested this on The Matrix:
> 
> -----------------------------------------------------------------
> for i in 1:turbo 2 ; do
>   time mencoder ~/dumpstream/matrix.vob -aid 128 -oac copy \
>   -vf crop=718:356:0:60,scale=640:272 -sws 9 -ovc lavc -lavcopts \
> vcodec=mpeg4:vbitrate=581:psnr:vpass=$i:mbd=2:mv0:trell:cbp:\
> precmp=2:cmp=2:subcmp=2:predia=2:dia=2:preme=2:vme=5:v4mv:\
> last_pred=2:vqcomp=0.6:vmax_b_frames=2:qpel -ofps 24000/1001 \
>   -o test.avi
> done
> 
> -----------------------------------------------------------------
> before:
> 
> (pass 1)
> PSNR: Y:40.06, Cb:44.34, Cr:44.64, All:41.10
> user    35m12.394s
> 
> (pass 2)
> PSNR: Y:42.10, Cb:45.17, Cr:45.85, All:42.96
> user    186m52.325s
> 
> 
> -----------------------------------------------------------------
> after:
> 
> (pass 1)
> PSNR: Y:40.05, Cb:44.29, Cr:44.59, All:41.08
> 
> (pass 2)
> PSNR: Y:42.04, Cb:45.15, Cr:45.84, All:42.91
> 
> -----------------------------------------------------------------
> 
> I don't have the user times listed for "after" because for some reason
> my CPU frequency scaling went screwy and stuck my CPU at a low
> frequency. Nevertheless, I don't think the encoding speeds are
> significantly different -- the user times for after the next commit were
>  34m52.509s and 190m8.100s, respectively for each pass.
> 
> Unfortunately, I didn't see a large PSNR gain like I had hoped from the
> log message. The PSNR actually dropped a bit. As for quality
> differences, here's the breakdown from looking at several different scenes.
> - mostly the same (low-motion scenes are all the same)
> - several places that look slightly better
> - a few places that look slightly worse
> - a few places that look significantly better
> - one place that looks significantly worse
> - one frame that looks way worse (flickering lightning for a second)
> 
> Overall, I have the impression that quality is improved.

good, i also havnt seen such huge PSNR improvments on all files, +1.00
was just the maximum IIRC, ill post the exact PSNR from my files as soon as
the system on which they are is up again (might take some time ...), i
should have posted them already when i did the testing
anyway its subjective quality that counts not PSNR

[...]
-- 
Michael