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Kat Manton · 3rd Mar 2006, 6:51 pm

Hi,

I'll just reply briefly to a few points; the problem regards the pixel clock on graphics cards is more of getting it to run slow enough for 405; I need to do more research on this but it looks likely there are cards in existence for which Linux drivers exist, and which ought to be able to be made to work.

The card I have (nVidia Geforce 4) has a driver which refuses to output anything other than 625 PAL and 525 NTSC from the S-Video output; but it will output anything you like and which the card can do from the RGB output. So it looks like the best approach is to combine R, G and B from the VGA output and add syncs. I've already done this partially to feed RGB and composite sync into the SCART input on my television, bypassing the PAL encode/decode process that happens using the S-Video input.

The rest of it's already there - the MythTV software already handles video capture, tuning, channel guide, and importantly interpolation, I can watch TV and DVDs fullscreen on 320x200, 720x576 interlaced PAL, up to 1600x1200 on a huge high-resolution monitor - it's just a question of working out the timings and writing an X modeline - and having a card which will run those timings. Once X is running in a particular resolution, MythTV will just use it.

So, all that needs to be done is to get X driving a video card at the resolution and timings we want, a little bit of analogue circuitry hung off the VGA connector, and the rest of it will just work.

So - I think it looks promising... I'll see what I can do.

If you'll excuse me, I'm not likely to be working on this for a little while having recently lost a very dear friend; but I'll get back into tinkering with technology at some point and let you know what happens.

All the best,

Kat

3rd Mar 2006, 6:51 pm	#16
Kat Manton Retired Dormant Member Join Date: Jul 2005 Location: West Yorkshire, UK. Posts: 1,700	Re: PC as a standard convertor Hi, I'll just reply briefly to a few points; the problem regards the pixel clock on graphics cards is more of getting it to run slow enough for 405; I need to do more research on this but it looks likely there are cards in existence for which Linux drivers exist, and which ought to be able to be made to work. The card I have (nVidia Geforce 4) has a driver which refuses to output anything other than 625 PAL and 525 NTSC from the S-Video output; but it will output anything you like and which the card can do from the RGB output. So it looks like the best approach is to combine R, G and B from the VGA output and add syncs. I've already done this partially to feed RGB and composite sync into the SCART input on my television, bypassing the PAL encode/decode process that happens using the S-Video input. The rest of it's already there - the MythTV software already handles video capture, tuning, channel guide, and importantly interpolation, I can watch TV and DVDs fullscreen on 320x200, 720x576 interlaced PAL, up to 1600x1200 on a huge high-resolution monitor - it's just a question of working out the timings and writing an X modeline - and having a card which will run those timings. Once X is running in a particular resolution, MythTV will just use it. So, all that needs to be done is to get X driving a video card at the resolution and timings we want, a little bit of analogue circuitry hung off the VGA connector, and the rest of it will just work. So - I think it looks promising... I'll see what I can do. If you'll excuse me, I'm not likely to be working on this for a little while having recently lost a very dear friend; but I'll get back into tinkering with technology at some point and let you know what happens. All the best, Kat