[MEncoder-users] new doom9 codec comparission (submission)

Corey Hickey bugfood-ml at fatooh.org
Tue Dec 13 22:07:46 CET 2005

Doom9 Feedback Hotline wrote:
>>Really? I thought 2-pass was a requirement. I'll try to make a suitable
>>3-pass setup then. That should be much better (and much slower, but snow
>>isn't really ready to compete for speed anyway).
> Actually what I meant to say was that one pass is also okay.. allowing 3 
> pass on the other hand is a whole other bag of problems because no other 
> participant was told 3 pass was allowable. So it really must be one or two 
> pass. If you find out that three pass turns out okay and is accurate on 
> size, I can mention that  but it doesn't change the fact that the rate 
> control apparently sucks.

Aww, crud. Please do mention that a viable method exists for 3-pass. I'm
going to write it up and submit a patch for DOCS/tech/snow.txt.

In that case, my best suggestion is still an educated guess, though I
know a bit more about what I'm doing now than I did before. The changes are:

pass 1: change vqscale to 1.8
pass 2: add lmin=1.8

That alters the full encoding line to be:

for i in vpass=1:vqscale=1.8 vpass=2:vbitrate=581:lmin=1.8 ; do
  mencoder matrix.vob -aid 128 -oac copy \
-vf crop=718:356:0:60,scale=640:272 -sws 9 -ovc lavc \
-lavcopts vcodec=snow:vstrict=-2:cmp=1:subcmp=1:mbcmp=1:\
qpel:vqcomp=0.6:$i -ofps 24000/1001 -o snow.avi

Doom9, please give it a try. Let's hope it works. :)


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