[mythtv-users] Can't adjust contrast, brightness etc in Mythtv .20

Bruce Markey bjm at lvcm.com
Wed Jan 17 03:40:37 UTC 2007

Robert Tsai wrote:
> On Tue, Jan 16, 2007 at 06:07:04PM -0600, Randy Ferrill wrote:
>> When I hit the F key and try to adjust birghtness , contrast , etc
>> it changes to a -1 and won't change.
>> PVR-250 and Nvidia Geforce 4MX card, FC5 and Mythtv .20.
>> I searched the archive and found 1 posting but no answer or replies
> I see the same thing. A few weeks ago I traced this problem down to a
> failure in VideoOutputXv::SetPictureAttribute; one of the X or Xv
> calls is failing.
> The caller TV::DoChangePictureAttribute does not check for the
> sentinel "-1" return value; hence you see "-1" in your OSD.
> I don't know why the X/Xv calls are failing. Too many things have
> happened since this was last working (distro/X.org upgrade, kernel
> upgrade, NVidia driver upgrade, etc.).

This used to be a common question a couple years ago. It reads
the current value then adds or subtracts 655. However, at some
point, it stopped being able to get the current value unless X
had the "v4l" module loaded. Make sure you have:

Section "Module"

    Load           "v4l"


in your /etc/X11/xorg.conf or whatever file is used for your
X configuration.

--  bjm

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