[MPlayer-users] lavc vs. xvid (and improving lavc quality)

[Matthias Wieser]

D Richard Felker III wrote:
> On Wed, Jun 02, 2004 at 12:34:44AM +0200, Matthias Wieser wrote:
> > Compared to xvid from summer 2002?
> > Just try yourself: Encode a movie with low bitrate and watch some
> > nearly flat areas - there the blocks are. Watch the movie with
> > postprocessing and you won't see those blocks. But not everyone uses
> > postprocessing.
>
> I never use postproc and I never see blocks.

You like high bitrates, am I right? ;-)

> BTW perhaps you're 
> (stupidly) using vqscale= rather than bitrate/2pass encoding.

No, I'm not (stupidly) using vqscale=. I'm using vbitrate=...
I'm mostly real-time encoding from cable TV with

mencoder tv:// -tv driver=v4l2:width=720:height=576:brightness=0:contr[...] \
-ovc lavc -lavcopts vcodec=mpeg4:vbitrate=2200:vratetol=32000:mbd=2:aspect=4/3 \
-oac mp3lame -lameopts abr:br=128 \
-vf crop=672:528:24:24,pp=md,scale=576:432,denoise3d=5:4:7 \
-sws 1 -o Video-`date +%d.%m.-%H%MUhr`.avi -endpos $1

High motion scenes (with higher quantizer) with sky tend to produce
block artifacts at the sky. It's understandable because the sky has
nearly no detail but nevertheless it would need just a bit more bitrate
than what mencoder allocates for the sky. If you use postprocessing the sky looks
OK (a bit like blue plastic - with some noise it looks even better).

IMHO there should be a possibility to tell mencoder or lavc "don't spend
nearly all bits on those fast moving objects (nobody will see those details
anyway) but reserve slightly more bits for seemingly simple flat areas
like sky, streets, walls and so on. (Xvid mode ?) That would make mencoder/
lavc more tolerant to people that don't / can't use postprocessing.


      Matthias