[MPlayer-users] RFC: docs update for "how to create a high quality DVD rip"

[D Richard Felker III]

On Mon, Jun 07, 2004 at 05:00:55PM -0500, Wayde Milas wrote:
> > > wondering if you should depend on spp, or just up the bit rate? Ie,
> > > should I be doing my tests by running the stream through spp for
> > > viewing, or just viewing it "as is"?
> > 
> > Upping the bitrate stops helping when every frame is already using qp=2.
> > spp helps clean up the image to a certain extent, and adding a bit of
> > noise helps even more, IMO.
> 
> Well, you dont want every frame to be q=2 do you? I was under the
> assumtion that you can get away wtih q > 2 on low motion frames.

No, the opposite. You want q=2 (or even 1) on low motion frames where
even minor artifacts will be visible. On high motion, 3 or 4 is fine.

> Let me ask this. Does q=2 use as much space on a fast motion frame as it
> does on a low motion frame? I always thought solid q values used about
> teh same bits no matter what they were encoding?

Nope, totally backwards. q=2 means you keep lots of precision, so it
uses however much space is needed to keep all that precision.

> Encode a 240 second chunk at various bitrates and graph it. PSNR values
> are not linear. Its that non linearity that has me pondering different
> schemes.

The PSNR values you see measure error logarithmically.

Rich