[Mplayer-dvb] picture quality of mpeg4 playback

[Martin Hoffmann]

A long time a go ... [in a galaxy far far away]
> > > it's a known bug. it seems to mpeg1 encoder adds this artifacts (maybe
> > some
> > > overflow) at very low qscale values.
> >
> > Is there any workaround at the moment ? Afaik higher qscale values would
> > result in more mpeg "noise" because of the higher compression. But maybe
we
> > can find a way to prevent the qscale to get too low ?
> > Or do you know if the developers of ffmepg already working on this ?
> >
> I told it to Gerard, but he is verybusy nowdays :(
>
> you can increase qscale at vo_mpegpes.c:162:
>     codec_context.quality=1; // quality!  1..31  (1=best,slowest)
>
> 2 or 3 should be ok (no visible quality loss)

You remember ?

I have played around with the q-values 1,2 and 3 and it seems that for
scenes with high contrast q=3 is the best and for scenes with very low
contrast q=1 or even lower would be the best :-(
Otherwise we get blocky picture (in scenes with fog and stuff) or those grey
artifacts at areas of high contrast start to appear !

Did i get something totally wrong, or are you using variable bitrate with a
constant quality ?
What about using constant bitrate instead ? Would this help ? And how high
could this bitrate be, for the DVBs card to handle ?
Maybe this could give better quality ?

Just an idea...

Martin.