[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.
>
>  I believe that your Q value is not relevant: why PSNR/bitrate rather than
>  PSNR²/bitrate or PSNR/bitrate², or PSNR/log(bitrate) or... PSNR itself is a
>  logarithm of mean square error, there is no reason that a simple division
>  should be the relevant measure.
 The Shannon-Hartley theorem
 (http://en.wikipedia.org/wiki/Shannon-Hartley_theorem) suggests to me
 that  information is proportional to the PSNR (I know I am stretching
 things here, and I may be wrong).
 

>  There is a case where the results are certain; if bitrate(A) <= bitrate(B)
>  while quality(A) >= quality(B), then it is certain that the settings for A
>  are better (quality-wise) that the settings for B.
>  Fortunately, in your tests, you are precisely in this case.
>
>  If this is not true, then you have to vary your target bitrate until you can
>  compare, or plot curves and see which one is above the other.
 Not feasible for me. I took many hours to perform the tests the way I
 did. It would take much more to perform them the way you suggest.
 
>
>  > Excellent quality:
>
> > secs  1201 frames PSNR: Y:35.48, Cb:38.85, Cr:38.26, All:36.28
>
>  I would not call that "excellent quality": I like my videos well above
>  PSNR 40.
 I call excellent quality because I achieved a high PSNR for the
 bitrate. Also, I am not a "videophile". The quality of the file above
 is high enough that, when watching with -vf pp=ac, I can hardly notice
 the compression artifacts even if I examine it very closely.
 

>  > 1) Do you think the above settings are wise? Any suggestions?
>
>  Do you insist on using simple MPEG-4? H.264 gives much better results.
 As far as I know, H.264 would take too much time to encode. Also, I
 don't like patent-encumbered codecs. I assume that MPEG-4 part 2
 patents will run out before those of H-264, so it is "less evil". Too
 bad mencoder does not support Theora. ffmpeg2theora is a bit raw to my
 perfectionist needs. In any way, MPEG-4 part 2 is more compatible with
 players.
 

>
>  Shameless plug: You may be interesting by a look at <URL:
>  http://www.normalesup.org/~george/comp/video_quality/
>   >. I have a second part in this experiment waiting to be published, where I
>  explore the effect on quality and time of the various encoding options, but
>  it still requires some work.
 Thank you very much, I will look into that.