[mythtv-users] Modeline / timings help; convert xorg to windows

Christopher Friend christopher_friend at hotmail.com
Fri Jan 11 20:45:08 UTC 2008

>> I had to do a modeline for my 51cm PAL TV to get 4:3 to stick properly. >> I too had problems with the nvidia driver ignoring what I out in and it >> complained about lot of things.
Thanks bruce, though i think you did yours for a regular tv out port? mine's going through vga so doesnt need all the Option "TV..." stuff... 
Anyway, I finally got it all working today. Along with having to connect a 1.5V battery to pin 16 to get it to switch to rgb (confused me for a while when it didnt work at first...), I also changed the xorg.conf file a bit to what's included below. Basically I just needed to tell it to ignore all EDID and pre-made modelines from anywhere, and set VertRefresh and HorizSync to the correct range.
Although it works OK now, I'm still getting problems with a jittery image (and complete blackouts of bits or the whole of the image every now n then for a second or so). Usually it's fine for the first 20 seconds or so, then I get slight jitter whenever there's much screen movement. It may be cable related, could be xorg related, could be myth related, could be driver related...
My Myth setup is basically no deinterlacing, fullscreen, most other stuff defaults. I've also tried changing the Sync To VBlank and blitter or whatever it was options in the Nvidia control panel, but they haven't changed much (though turning the first off gave me glxgears output of 251 in 5 secs @ 50 fps, i think that's correct. FWIW I'm using Nvidia driver 9755 on Ubuntu 7.04. Using deint (either kernel or linear) gives a mostly stable image with no change in quality, but it's not as good as using no deint while it's working well.
Also when using the manual zoom to make the image smaller I get even worse interlacing type bars across moving images, I've stuck a folder of example pics at http://www.inaudible.co.uk/temp/myth/ , 18's probably the best technical example.
The xorg.conf file I'm using is at http://www.inaudible.co.uk/temp/myth/xorg_tv.txt and the log at http://www.inaudible.co.uk/temp/myth/xorg_log.txt , which looks fine in regards to loading the correct modeline.
Does anyone have any ideas what may be causing the jitter / interlacing? Or has anyone out there set up myth with a vga to scart rgbs cable and nvidia driver, and know what kind of settings I should be trying out? Any other random advice? Xbox make a good frontend? Ok bit OT now...
I'll be adding everything I've done so far to the wiki asap, but much thanks goes to Steve Hill @ http://www.nexusuk.org/ for the original guide for the cable :o)
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