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

Loren Merritt lorenm at u.washington.edu
Tue Dec 13 08:21:58 CET 2005

On Mon, 12 Dec 2005, Corey Hickey wrote:
>> 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...
> ...and it doesn't work well. The bitrate ends up being fine, but PSNR
> drops from 43.01 to 42.54. Low-motion parts look a bit better (probably
> from the lower vqmin), but high-motion parts are much worse.
> I'm currently testing a few possibilities:
> - without vqmin=1:lmin=1
> - vqmin=1:lmin=1.5
> - vqmin=2:lmin=1.5
> - starting over again with vqscale=1.5 for the first pass
> I don't know which of those is the right approach, but we'll see.
> I'd really like to come up with a generic two-pass method of snow
> encoding so it isn't necessary to find a specific vqscale value for the
> first pass of each encode. If I can't, than I think I'd rather see snow
> disqualified than look bad because I can't work around the lack of first
> pass ratecontrol.

Another possibility is
which should avoid the defecit of bits in high-motion parts.

Note: snow ignores vqmin. The limit is only lmin.

--Loren Merritt

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