[mythtv-users] Troubleshooting a VGA-SCART converter

Petteri pjokinen at lavabit.com
Mon Oct 3 15:49:33 UTC 2011

02.10.2011 21:55, Alex Butcher kirjoitti:
> On Mon, 3 Oct 2011, Andrew Cranwell wrote:
> ...however, when I bought a new GT240, I found that X would accept the
> modelines, but the card wouldn't output a signal that my TV would
> display. My (relatively untested) theory is that any card with an analogue
> composite/S-Video output can output modelines with <15MHz dot clocks, but
> that cards with only HDMI TV outputs can't. I suspect you're out of luck
> with your GT520.

I'm using nexusuk adapters with GT210 and GT220 and neither have 
analogue tv-out.

>> I suspect the first problem is that the scan frequencies are simply too
>> high - X doesn't seem to accept the 15.6kHz modelines (from
>> http://www.mythtv.org/wiki/Modeline_Database) but will use the 31kHz
>> non-interlaced modes - hopefully this will actually work as the TV can
>> supposedly take 100Hz progressive input.

If X isn't accepting modelines you should add ModeValidation and UseEDID 
config lines to xorg.conf and disable (all) validation checks (they are 
useless anyway with the adapter).

I'm using nexusuk adapters with two 36" CRTs @1024x576/25i and picture 
quality is excellent so it is worth the hassle IMO.

For fine-tuning modelines I used glxgears with vsync to adjust output to 
exactly 50.000 hz.

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