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

[Corey Hickey]

Michael Niedermayer wrote:
>>Assuming that I've reproduced the same environment as Doom9, that likely
>>means the DVD I used is different, somehow. Maybe it's more grainy.
> 
> 
> one way to check that would be to cut out a short part of the mpeg2 bitstream
> of both and compare them in some player side by side ...

Yeah, I suppose it's come to that. I've placed a 200MB clip from the
beginning of mine at:

http://fatooh.org/files/doom9tmp/matrix-200MB.vob

Doom9, if you read this, could you please do the same with as much as
you're comfortable? 200MB is more than enough. Also, feel free to send
me the URL in a private email.

Meanwhile, I'm going to continue trying to find a more generic way to
work around the lack of first-pass ratecontrol. I should have done that
in the first place...

>>>i would guess that lmin was too large, though its not clear how it could
>>>have worked for corey ...
>>
>>Does lmin have any effect on the constant-quantizer first pass? I'm
> 
> hmm, IMHO no

Yeah. My experiments after I sent the last email seem to show that
vqscale overrides both vqmin and lmin.

>>figuring that if the first pass hadn't used such a low bitrate, then the
>>second pass would have used the specified bitrate.
>>
>>Doom9 pass 1: 479.429
>>Doom9 pass 2: 519.393
>>
>>   my pass 1: 592.388
>>   my pass 2: 581.367
>>
>>
>>Right now, I'm testing whether it would work fine to ask Doom9 just to
>>use vqscale=1 for the first pass, which is way lower than what it needs
>>to be. If that ends up working fine, it's an easy solution that also has
>>the benefit of not needing to be adjusted for different encodes (except
>>for very-high-bitrate ones).
>>
>>Any comments?
> 
> 
> if qscale=2.15 is significantly below the target then =2 will be too, and
> lmin has a default of 2 IIRC so i dont think the second pass will reach
> the target size no matter what you change in the first pass

Yeah, I didn't realize that the vqmin and lmin defaults would be too
high until a few minutes ago. I'm starting to think that maybe I should
do this:

First pass:  vqscale=1
Second pass: vqmin=1:lmin=1:vbitrate=581

I'm testing this now...

-Corey