[mythtv-users] Watching LiveTV with a Matrox G200

digitom digitom at users.sourceforge.net
Tue Sep 26 16:23:52 UTC 2006

Hello Martin,

thanks for your post. That's it!

But you're right, my computer (1,4 Ghz) is to slow without the backend

hmm, moving base-adress of video mem ? Sounds god, but  i think
it will be very tricky, or not ??

I can't estiminate where to start ..

I would also try it again with my radeon, but this video card has a
minimal pixel-clock of 20 Mhz
(14 Mhz minimal pixel-clock for the Matrox G200)
And for the pal standart i need a horizontal-freq. of 15,625 Khz.

So my minimal horizontal resolution is = dotclock / hfreq = 1280 px
(radeon card)
My dvb TV supplies only a horizontal resolution of 720 px ..

When i swicth to aspect ratio 16:9 then the TV-Show is at 4:3 at my
But i think this is not the best solution.

Don't know witch way to go, but i will find the right solution. sure.
I want use RGB to Scart .. any idea ?

thank in advance,

Martin Ebourne schrieb:
> On Mon, 25 Sep 2006 23:18:38 +0200, digitom wrote:
>> My MythTV works almost fine, until i have changed the video card. The
>> Matrox G200 is better for TV-Out then the Radeon. (TV-Out over VGA-RGB to
>> Scart with an resolution of 720x576 at 50Hz)
>> ...
>> In fact, the only thing that is not working, ist watching TV in
>> Fullscreen-mode.
>> When i switch to LiveTV (dvb-s) or want to watch a record i get only a
>> blue-screen.
>> The remote works, and sound is also ok. I can also see the preview-video
>> at the recordings.
> The problem as you suspected is XV. The matrox cards just do not support
> the Backend Scaler (as used by XV) on interlaced output (including the
> tvout).
> You can set the environment variable NO_XV=1 before running mythfrontend
> which will disable XV and will get you a picture. Unfortunately it will
> use more processor (or at least more bus bandwidth which has a similar
> effect), and crucially the double buffering provided by XV will be lost.
> Hence you will get tearing of the picture.
> The card provides vsync, and if someone implemented double buffering by
> moving the video base address it could be made to work very well. DirectFB
> gets close on the G400 and above but compiling MythTV for it is not very
> rewarding in my experience.
> Cheers,
> Martin.
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