I've just taken the jump from an SD s-video telly to an HD HDMI telly (a 32" samsung). Litterally, 10 minutes ago...
YMMV, Mine's a 16:9 LCD, so your's may be different, but here's what I did.
Find the resolution for the telly:
It was in the manual, as it's a standard LCD mine's 1366x768.
Find modeline(s):
I went to the mythtv wiki, where people have posted modelines, and I took anything that was 136*x768. I say 136* because I've heard some people having better results with 1360, and there were a few 1368 ones on the page too, so I took them all, and I ended up with a list:
Code:
Modeline "1368x768-1" 85.478 1368 1424 1536 1792 768 771 777 795 +hsync +vsync
Modeline "1368x768-2" 85.478 1368 1424 1536 1792 768 771 777 795 +hsync +vsync
Modeline "1366x768-3" 85.500 1360 1440 1552 1792 768 771 777 795 +hsync +vsync
ModeLine "1360x768-4" 85.5 1360 1424 1536 1792 768 771 777 795 +hsync +vsync
Modeline "1360x768-5" 84.50 1360 1392 1712 1744 768 783 791 807 +hsync +vsync
Modeline "1360x768-6" 85.50 1360 1476 1588 1776 768 771 777 795 +hsync +vsync
Modeline "1360x768-7" 85.5 1360 1416 1528 1792 768 771 777 795 +hsync +vsync
Modeline "1360x768-8" 72.000 1360 1424 1456 1560 768 771 776 790 -hsync +vsync
ModeLine "1360x768-9" 84.6 1360 1424 1568 1776 768 769 774 795
Modeline "1368x768-A" 85.50 1368 1478 1590 1776 768 771 777 795
Modeline "1360x768-B" 85.500 1360 1432 1544 1792 768 771 777 795
Modeline "1360x768-C" 84.50 1360 1392 1712 1744 768 783 791 807
Edit Xorg.confI then inserted these into the monitor section of my xorg.conf file, and also edited the screen section to look like this:
Code:
Section "Screen"
Identifier "Screen0"
Device "Card0"
Monitor "Monitor0"
DefaultColorDepth 24
SubSection "Display"
Depth 24
Modes "1368x768-1" "1368x768-2" "1366x768-3" "1360x768-4" "1360x768-5" "1360x768-6" "1360x768-7" "1360x768-8" "1360x768-9" "1368x768-A" "1360x768-B" "1360x768-C"
EndSubSection
EndSection
I also commented out my "ConnectedMonitor" and "TVOutFormat" options in the xorg.conf.
Connect the telly
I plugged an HDMI > DVI cable into my telly + 6600GT in the myth box
Rebooted, and it worked.
The details my be different for you, but the process should be similar.
Good luck, I'm just stunned by the quality of my set, it's lovely