[MEncoder-users] High quality encoding of anime and broken mencoder options

[Jorge Peixoto de Morais Neto]

Hi. I seek high quality encoding of anime. I have tested
many encoding options, always with vcodec=mpeg4 and 2-pass encoding. 
I have found that even with vbitrate, the actual bitrate depends on
the options used. Therefore, to keep the comparison fair, I have
measured encoding quality by Q=PSNR/bitrate, with bitrate in Mbits/s.

The test source is a 105 MB avi file with FFV1 video and no audio. The
video is 1201 576x432 frames at 25fps. 

Some of my results:

Very fast:

time mencoder -o result.avi -ovc lavc -lavcopts
vcodec=mpeg4:psnr:vbitrate=512:vpass=2 testsource.avi

Video stream:
538.354 kbit/s  (67294 B/s)  size: 3232815 bytes  48.040 secs  1201
frames PSNR: Y:33.86, Cb:37.82, Cr:37.20, All:34.77

real    0m30.771s
user    0m27.979s
sys     0m0.608s
u+s=28.587, fps=42.01, PSNR/bitrate=64.59

High quality:

time mencoder -o result.avi -ovc lavc -lavcopts 
vcodec=mpeg4:psnr:vbitrate=512:keyint=300:vmax_b_frames=2:vb_strategy=1:b_sensitivity=10:trell:v4mv:mbd=2:vpass=2
testsource.avi

Video stream:  510.746 kbit/s  (63843 B/s)  size:
3067029 bytes  48.040 secs  1201 frames PSNR: Y:34.89, Cb:38.66,
Cr:38.03, All:35.77

real    0m44.823s
user    0m41.348s
sys     0m0.788s
u+s=42.136, fps=28.5, PSNR/bitrate=70

Excellent quality:

time mencoder -ovc lavc -o result.avi -lavcopts 
vcodec=mpeg4:psnr:vbitrate=512:mbd=2:mv0:trell:v4mv:cbp:last_pred=3:predia=3:dia=3:vmax_b_frames=2:vb_strategy=1:b_sensitivity=10:mbcmp=2:qpel:preme=2:keyint=300:vpass=2
testsource.avi

Video stream:  498.805 kbit/s  (62350 B/s)  size: 2995322 bytes  48.040
secs  1201 frames PSNR: Y:35.48, Cb:38.85, Cr:38.26, All:36.28

real    1m32.845s
user    1m30.364s
sys     0m0.943s
u+s=91.307, fps=13.15, PSNR/bitrate=72.73


Now, 
1) Do you think the above settings are wise? Any suggestions?
2) When reencoding a movie with slight compression artifacts, should I
use -vf pp=ac? Note that I will use it when reproducing anyway; I am
asking if I should also use it during encoding.
3) The option vrc_override should be useful,
but does not work. That should be added to the documentation.

Thank you for your attention!

-- 
Software is like sex: it is better when it is free. --Linus Torvalds