[MPlayer-users] Scenes badly encoded with qscale=2 (was Re: Tips for encoding)

[Rémi Guyomarch]

On Sun, Oct 27, 2002 at 02:49:26PM -0300, martin pavon wrote:
>  --- Rémi Guyomarch <rguyom at pobox.com> escribió:
> > 
> > Try adding "vqcomp=0.7:vqblur=0.2:mpeg_quant" to lavcopts.
> > 
> > Could you post a sample of the problematic scene somewhere (*not* the
> > encoded version) ?
> 
> I tried your suggestion and it improved the image a little ... but not
> enough. I was playing with different options and I couldn't find the way.
> I suppose that the vob is not so good (watching it in TV trough the
> computer looks better than my endoding, but it isn't a lot of better).
> 
> If you have time and want to play a while, I upload the scene to
> 
> http://mate.dm.uba.ar/~mpavon/tmp/

Yes, those scenes with qscale=2 looks terrible :-(

Try with vqmin=1 in addition to mpeg_quant:vlelim=-4:vcelim=-7 (and
maybe with "-sws 10 -ssf ls=1" to sharpen a bit the image) and read
about vqmin=1 in DOCS/tech/libavc-options.txt.

If after the whole movie is encoded you still see the same problem, it
will means that the second pass didn't picked-up q=1 for this
scene. Force q=1 with the "vrc_override" option.

> By the way, is there a special difficult in encode clouds or smoke?

I would say it depends on the sharpness of these clouds / smokes and
the fact that they are mostly black/white/grey or colored. The codec
will do the right thing with vqmin=2 for example on a cigarette smoke
(sharp) or on a red/yellow cloud (explosion, cloud of fire). But may
not with a grey and very fuzzy cloud like in the chocolat scene.
Note that I don't know exactly why ;)

Btw, "Chocolat" is a wonderful movie !

PS: I'm Cc'ing this to the ffmpeg/libavcodec list.

-- 
Rémi