[MPlayer-dev-eng] samples which look bad when encoded with lavc 2-pass needed

[Michael Niedermayer]

Hi

On Monday 22 July 2002 02:17, D Richard Felker III wrote:
> On Mon, Jul 22, 2002 at 01:48:28AM +0200, Michael Niedermayer wrote:
> > Hi
> >
> > On Monday 22 July 2002 00:07, Arpi wrote:
> > [...]
> >
> > > Hmm. I don't think that divx4's (xvid use the same) 2pass code is
> > > better... i've hacked it too much to know it's shit. Imho your code is
> > > far better, _but_:
> > > - no one experienced with good values - defaults aren't the best imho
> >
> > i know, the defaults are mostly just randomly choosen without much
> > testing, ill fix these (vqmin should be the lowest bugfree quantizer
> > depending upon the used codec, ...)
>
> How about fixing msmpeg4 so qscale=2 works? If it's not possible to
> override qscale on a per-mb level when there are overflows, how about
> just re-encoding the whole frame at qscale=3 if when 2 generates an
> overflow? That should fix the issue and make higher quality encoding
> possible too.
it would be possible, but not even M$ does that, nah i doubt they even know 
what overflow means ...
we could use 2-pass for that, just mark the overflow and raise qp in the 2nd 
pass for that frame

>
> > > anyway i also experienced - and read on -users too - a possible bug:
> > > when the input media is too low quality, so there are parts where the
> > > maximum reachable bitrate (due to high qmin or missing data) is under
> > > the wanted one (calculated by 2pass algo), it doesn't (or at least it
> > > seems it doesn't) distribute these 'free' bits for the remaining part
> > > of the movie.
> >
> > someone should upload such a file
>
> I think any movie with lots of very low motion scenes and some
> high-motion ones should demonstrate the problem, if you tune the
> bitrate appropriately. Ghost in the Shell DVD is my favorite example
> of the problem.
hmm, lets hope it works with divx3 gits too as i have no dvd drive (and dont 
need one either)

[...]

Michael