r200 xvideo gamma curve

[Edgar Toernig]

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?

Anyway, I would prefer the gamme curve produced by this
patch at any time:

--- a/src/radeon_video.c
+++ b/src/radeon_video.c
@@ -547,9 +547,9 @@ static GAMMA_CURVE_R100 gamma_curve_r100
 static GAMMA_CURVE_R200 gamma_curve_r200[8] =
  {
        /* Gamma 1.0 */
-      {0x00000040, 0x00000000,
-       0x00000040, 0x00000020,
-       0x00000080, 0x00000040,
+      {0x00000100, 0x00000000,
+       0x00000100, 0x00000020,
+       0x00000100, 0x00000040,
        0x00000100, 0x00000080,
        0x00000100, 0x00000100,
        0x00000100, 0x00000100,

Ciao, ET.

[1] As I have no docs, I've no idea what these values
really mean so I simply tried some settings.