[MPlayer-users] Bicubic scaling in vo_gl - does it ever work?

[Vladimir Mosgalin]

Hi Reimar D?ffinger!

 On 2006.07.01 at 13:07:44 +0200, Reimar D?ffinger wrote next:

> I think I found what caused the problem. I don't fully understand the
> specs there, so I'm not even sure if it is a driver or MPlayer bug (it
> seems that sometimes the default texture bindings were in the way that
> by default texture unit 0 and 3 used the same texture).

But what solved the bug then? I updated drivers and xorg, not mplayer.

> > message on mplayer exit, and second is that yuv=4 stopped working. It
> > displays garbage even without lscale or cscale right now.
> 
> At least this should be fixed (though the problem appeared for me only
> sporadically).

The problem with yuv=4, both with or without lscale/cscale, is the same
as with yuv=4 and lscale before. It looks like.. um.. well you take the
video, and put brightness almost at zero. You won't see a thing, of
course; but increase saturation and though the overall brighness would
be very low, you'll see colors, especially ones such as bright red (as
dark red). The picture with yuv=4 looks very much like that, but the
overall brightness is almost at zero, and on the other hand you see
colors without increasing saturation.

I.e. black and white become black, regular colors become very dark, and
very bright colors stay almost the same.

> > BTW, can you ever notice effect from cscale?
> 
> I can't. Seems like eyes are horrible at seeing colour differences...
> Or it is a bug. I can't use it at realtime speeds anyway though.

I noticed it; however, I don't think it ever improves the picture.
If you want to see the difference, find a video with high color contrast
or increase saturation; anime would do the best. Now look at subtitles,
like white subtitles with black outline. I'm talking about hardcoded
subtitles here. Right where outline ends there is high contrast area
from black - no color to saturated color. You'll see it the difference
between cscale=0 and 1 (or between -sws 2 and -sws 6) pretty clear.

Imho bicubic chroma scaling isn't useful at all.

-- 

Vladimir