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

Corey Hickey bugfood-ml at fatooh.org
Mon Dec 12 22:17:33 CET 2005

Corey Hickey 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 ...

Well, I've taken a look and they are way different. The graininess is
about the same, but the color, contrast, cropping and scaling are all off.

Take a look at some frames:

> 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.


More information about the MEncoder-users mailing list