[mythtv-users] Global colour saturation

[Bruce Markey]

Steve Hill wrote:
> Is there a global colour saturation control anywhere in Myth?  F5/F6 seems 
> to work on a per-channel basis, but my TV card always seems to 
> under-saturate the colours in the picture so I need some way of turning up 
> the colour on all channels (and I don't much feel like manually changing 
> the settings for each of the 70 or so channels I have set up).

BTW, if you are using bttv cards, espcially WinTV cards, the
whole color range is distorted. If you are running a kernel
and bttv driver with V4L2 support, there is a pretty good
fix.

$ v4lctl -c /dev/video0 setattr 'chroma agc' on
$ v4lctl -c /dev/video0 list
attribute  | type   | current | default | comment
-----------+--------+---------+---------+-------------------------------------
norm       | choice | NTSC    | PAL     | PAL NTSC SECAM PAL-Nc PAL-M PAL-N NTSC-JP PAL-60
input      | choice | Televis | Televis | Television Composite1 S-Video
audio mode | choice | mono    | mono    | mono stereo lang1 lang2
bright     | int    |   35500 |   32768 | range is 0 => 65535
contrast   | int    |   24500 |   32768 | range is 0 => 65535
color      | int    |   32768 |   32768 | range is 0 => 65535
hue        | int    |   32768 |   32768 | range is 0 => 65535
mute       | bool   | off     | off     |
chroma agc | bool   | on      | off     |
combfilter | bool   | off     | off     |
automute   | bool   | on      | off     |
luma decim | bool   | off     | off     |
agc crush  | bool   | on      | off     |


This turns on Automatic Gain Control which nornmalizes the
chroma signal strength. I have AVerTV cards that default to
over saturated and WinTV cards that are not only undersaturated
but distorted so that medium colors are even weaker than solids.

After turning on AGC, the colors are much truer for all models
of cards and almost identical from card to card. It doesn't
appear that the ivtv driver has an equivilant and this attribute
isn't available for bttv with the old V4L interface.

--  bjm