[MEncoder-users] new doom9 codec comparission (draft 1)

[Corey Hickey]

Guillaume POIRIER wrote:
>>for i in vpass=1:turbo vpass=2 ; do
>>  mencoder matrix.vob -aid 128 -oac copy \
>>-vf crop=718:356:0:60,scale=640:272 -sws 9 -ovc lavc \
>>-lavcopts vcodec=mpeg4:vbitrate=581:mbd=2:mv0:trell:cbp:\
>>precmp=2:cmp=2:subcmp=2:predia=2:dia=2:preme=2:v4mv:\
>>last_pred=2:vqcomp=0.6:vmax_b_frames=2:qpel:$i \
>>-ofps 24000/1001 -o mpeg4.avi
>>done
> 
> 
> I note that you force the framerate to 24000/1001... I don't know what
> kind of source doom9 is gonna use, but it may not be NTSC dvds
> (mencoder need the framerate of those sources to be set). I also note
> here that you did not use any inverse telecine filters. Is that
> intended?

Yes. The source for the preliminary evaluation (where we compete against
xvid alone) is the U.S. release of The Matrix. I played it all the way
through with "-vo null -nosound -benchmark" to check, and it is entirely
soft-telecine.

> I have little experience with ntsc contents, but if I'm not mistaken,
> failure to properly inverse telecine results in artifacts and bad
> picture quality.

Lots of bad things happen if inverse telecine is needed but not used.
MEncoder drops frames to maintain the output framerate and faithfully
tries to reproduce the interlacing. This makes the movie ugly, jerky,
and blocky because such things ruin compressibility.

> Now, doom9 is maybe using a frameserver such as avisynth which can
> probably do all the filtering, I don't know.

Unless I've been misled, it will be mencoder all the way. I have it set
up to use the exact same cropping and scaling parameters as Doom9 will
use for the other codecs. Actually, if it were my own encode I would
crop the vertical edges a couple more pixels to get rid of the black
border completely, but I can't do that here because it should be fair.
Besides, Doom9 would probably notice. :)

> Those are the kind of details that matter a great deal if they are
> forgotten or not well made.

Yes. Thanks for pointing them out.

-Corey