r200 xvideo gamma curve

[Edgar Toernig]

Alex Deucher wrote:
>
> On 10/14/06, Edgar Toernig <froese at gmx.de> wrote:
> > Hi,
> >
> > I wasn't satisfied with the quality of the xvideo overlay.
> > Dark areas had a very low color resolution giving large
> > patches of the same color without any details.  At 6.9
> > release time a looked at radeon_video and noticed that
> > the gamma curve seems to be non-linear at gamma 1.0.  I
> > changed it[1] and IMO the picture is much better now - dark
> > areas have much more details.
> >
> > Is the gamma curve supposed to be non-linear or is it just
> > some kind of "make dark areas black" hack?
> >
> 
> The values for the various gamma setting were given to me by ati.  As
> you can see the entire curve can be adjusted, I just picked the preset
> values ati offers in their windows driver.  If your changes make a
> good improvement, I'm happy to apply the patch.

I changed the values when I noticed, that mplayer output looked
much better when using -vo x11 instead of -vo xv.  With the
patched gamma settings, I can no longer see a difference between
the two.

> If you have ideas any further enhancements let me know and we
> can discsuss the hardware capabilities in detail.

Well, somehow the other gamma settings look kind of broken - they
produce major color artifacts.  Is it possible that there are
some arithmetic overflows during the conversion?

Ciao, ET.

PS: As I've found no tool to set Xvideo attributes, I've written a
small cmd-line tool to query and change the settings.  If someone's
interested ...