[MPlayer-dev-eng] 3 pass encoding syntax poll

[Loren Merritt]

On Wed, 9 Feb 2005, Guillaume POIRIER wrote:
>
> By the way: How many people actually use lavc's turbo mode? Are you
> globally happy with it?
> I do think there still is some room for improvement. When I implemented
> it, I did a global and frame-by frame PSNR comparison and and noticed
> very little PSNR difference, but and wasn't able to notice any artefacts
> on the video which first pass was ran with turbo mode.
>
> Can anybody give me some feedbacks about that feature?

I don't actually use the turbo option, I use 3-pass encoding with manually 
selected settings for each pass. But on reviewing the code, I see:

> /* Disables diamond motion estimation */
> lavc_venc_context->pre_dia_size = 0;
> lavc_venc_context->dia_size = 0;

dia_size=0 is identical to dia_size=1.

> lavc_venc_context->mb_decision = 1;

In my experience, mbd=1 is only slightly faster than mbd=2, and 
significantly lower quality. The only options are mbd=2 or mbd=0:mbcmp=2. 
And the latter works fine for a fast 1st pass.

--Loren Merritt