[mythtv-users] Washed-out areas in video output

Brian Wood beww at beww.org
Wed Jun 21 21:42:03 UTC 2006


On Jun 21, 2006, at 1:02 PM, Nathan Smith wrote:

> On Wed, 21 Jun 2006, Brian Wood wrote:
>
>>
>> On Jun 21, 2006, at 11:03 AM, Nathan Smith wrote:
>>
>>> Hello everyone,
>>>
>>> When I play TV (live) in myth on my 24 dell LCD monitor, the white/
>>> light
>>> areas bleed into one another. It sounds like a contrast or  
>>> brightness
>>> issue, but the black areas are not overly black (they look about
>>> right),
>>> and skin tones look perfect. Also, when I watch live tv with my
>>> normal old
>>> tv (using the tv-out port on my video card), the image looks fine.
>>>
>>> I tried changing the contrast on my monitor, and it just made the
>>> whole
>>> image more grey, with the same washed-out effects that I was
>>> experiencing.
>>> Could these washed-out areas be a function of XvMC (I heard XvMC is
>>> broken
>>> in 0.19 anyway?), or is it caused by a setting I'm not aware of, or
>>> are
>>> LCD monitors just not that great for watching tv with myth? Thanks
>>>
> ..............
>>
>> Since you mention using the TV out with your "normal old" TV, I
>> assume you are using the VGA or DVI output of your video card to
>> watch TV on your LCD ?
>
> Yep, I'm using the DVI output.
>
>> What sort of LCD monitor are you trying to watch TV on? how is it
>> connected up?
>
> The monitor I'm using is a Dell 24inch 2405FPW, which is relatively  
> new..
> I also tried hooking up my (old, about 2002ish) Samsung 17inch LCD (I
> think a multisync??), and it looked the same.
>
>> It sounds as though you might be overdriving your LCD with too much
>> luminance signal. Unfortunately there isn't much you can do about
>> that beyond your brightness control, which you don't mention trying
>> but I assume you have.
>
> Right I did mess with the brightness, but kind of like the contrast
> controls, it just made the washed-out whites a little less white, but
> still washed-out.. I was thinking I may be using the wrong color-set
> somewhere, but mass searches of google and helps didn't offer any  
> help on
> that. Any other ideas?

Well you seem to have eliminated the monitor as the cause.

So it's either a hardware problem with your video card or (more  
likely) a settings problem with your video driver/x-server.

If you have an nVidia video card and are not using the nVidia drivers  
you might try doing so, conversely, if you have and you are, you  
might try the open-source "nv" driver. If nothing else this might  
help pin down if the driver/settings are the problem.

nVidia has an "nvidia-settings" application that gives you pretty  
good control over the video parameters. Xset gives you some control  
over the X server's output.

There is (or at least was) an app called videodevX that gave some  
control.

Different Linux distributions have different applications to tinker  
with the video output, you might check for what yours has in that area.

I am assuming the following:

You do not have something connected to both the VGA and the DVI  
connector, this can cause problems with some cards.

You are using a "normal" good-quality cable to connect your monitor  
(no adapters etc., or hand-spliced cables, or 200-foot runs).

You are not going through a KVM switch.

That monitor with a decent video card should look good, with Myth or  
any other app. I'm sure we can get to the bottom of the matter.








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