I've been looking around for information on doing this - the basic idea is that VGA is mostly compatible with SCART, but the sync lines have to be combined and the video card must bring the horizontal scan from 31khz to 15khz - effectively, make the video card output true low-res and display it on a TV.
The first problem I'm trying to deal with is the video output - getting the modeline to work inside an X11 config. For some reason it's not accepting my modelines, and then trying to set ridiculous sync rates (0.3/300).
The second one is finding a working circuit to combine the sync lines. I've found 2 here and another one here. The one on the last page is the simplest by far, and the one I'll try when I can get X outputting a decent signal.
So, if anybody has tried to pull this off, which sort of circuit did you use? Also, could I see the X11 config to make it work?
And how many TVs did you kill in the process?
VGA to SCART conversion
Are you looking to convert 480p ro 480i?
640X480 31Khz to 640X480 15 khz (interlaced)
I highly doubt if any device can do this in a nice manner.
Or do you want 640X480 31 Khz to 320X240 15 Khz.
Please specify exactly what you want.
I'd like to be able to go from 640X480 31Khz to 640X480 15 khz (interlaced)
or from 640X480P to 320X240P.
Two lines must become as one
Interesting topic. It could probably be done but, probably not in the quality we'd like it to be, or can it? Hmmmmmm...
640X480 31Khz to 640X480 15 khz (interlaced)
I highly doubt if any device can do this in a nice manner.
Or do you want 640X480 31 Khz to 320X240 15 Khz.
Please specify exactly what you want.
I'd like to be able to go from 640X480 31Khz to 640X480 15 khz (interlaced)
or from 640X480P to 320X240P.
Two lines must become as one
Interesting topic. It could probably be done but, probably not in the quality we'd like it to be, or can it? Hmmmmmm...
I strongly suggest reading the EasyMAMECab Modeline Howto:
http://easymamecab.mameworld.net/html/monitor1.htm
Read it start to finish, twice. I did the same, and it explained everything I've ever needed to know about modelines, monitors and output frequencies.
http://easymamecab.mameworld.net/html/monitor1.htm
Read it start to finish, twice. I did the same, and it explained everything I've ever needed to know about modelines, monitors and output frequencies.
Yay, got it. That wasn't too bad... the single transistor circuit given on the XonTV page works fine. I pulled the vga connector off an old video card, wired everything into my dreamcast SCART plug, and, well, it works. I got one modeline working (640x240), but eventually gave up and let advancemame figure all that out. The only problem left is reducing the overscan so everything fits on the screen.
I managed to do this without killing anything, fortunately. Though my dreamcast scart plug looks horrible, and I managed to close my knife onto my finger.
Icarus: Where's the fun in that? Anyway, looks like it'll be doing some sort of scaling... Oh, and this cost me nothing.
D: I didn't want to convert anything, just get my laptop to output something*240 at 15khz, so that my tv could display it. I should be able to do 640x480i, but my video card doesn't seem to like it.
elvis: I ended up picking up that stuff from an X11 monitor timings document. Your link is clearer though, would have been nice to see that one first. I don't know why I couldn't figure out the modeline I wanted...
I managed to do this without killing anything, fortunately. Though my dreamcast scart plug looks horrible, and I managed to close my knife onto my finger.
Icarus: Where's the fun in that? Anyway, looks like it'll be doing some sort of scaling... Oh, and this cost me nothing.
D: I didn't want to convert anything, just get my laptop to output something*240 at 15khz, so that my tv could display it. I should be able to do 640x480i, but my video card doesn't seem to like it.
elvis: I ended up picking up that stuff from an X11 monitor timings document. Your link is clearer though, would have been nice to see that one first. I don't know why I couldn't figure out the modeline I wanted...
弾もまたいで通る
Use the advv or advcfg utilities. If you built AdvanceMAME from source, you might need to do a "make v" and "make cfg" to actually make those programs.ReKleSS wrote:Yay, got it. That wasn't too bad... the single transistor circuit given on the XonTV page works fine. I pulled the vga connector off an old video card, wired everything into my dreamcast SCART plug, and, well, it works. I got one modeline working (640x240), but eventually gave up and let advancemame figure all that out. The only problem left is reducing the overscan so everything fits on the screen.
ReKleSS,
Did you get your modelines working in X11? It's usualy pretty straight forward. One probelm that can arise is that if you are using a drive that is almost but not quite compattible with your video card then you might have trouble getting non-standard modes to come out right. The standard 'vga' driver is very restrictive on what it will allow too (definately no TV timimgs) as I remember.
If getting AdvanceMAME setup is what you're trying to acheive then make sure you adjust the TV (eliminate overscan, etc) before trying to tweak video modes in software.
Overclocking/Underclocking are terms you don't usualy apply to monitors (so you sentince is ambiguous without some context). What it could mean is: don't drive the horizontal/vertical sync lines at speeds beyond what your monitor is specified for (common sense, really). A typical modern TV horizontal stage will probably be unharmed by a signal that's way out of range (though that's certaintly no guarantee). Eg, plugging a high definition video signal into a normal old TV usualy doesn't end the TV's life prematurly. Running just a bit out of range (say, a 17KHz horizontal signal) for a long period of time wouldn't be a good idea and it's possible that it could shorten the life of the components in the TV's horizontal output stage. I suspect the typical failure due to this kind of abuse would be something relatively minor like a blown horizontal output transistor.
Did you get your modelines working in X11? It's usualy pretty straight forward. One probelm that can arise is that if you are using a drive that is almost but not quite compattible with your video card then you might have trouble getting non-standard modes to come out right. The standard 'vga' driver is very restrictive on what it will allow too (definately no TV timimgs) as I remember.
If getting AdvanceMAME setup is what you're trying to acheive then make sure you adjust the TV (eliminate overscan, etc) before trying to tweak video modes in software.
Overclocking/Underclocking are terms you don't usualy apply to monitors (so you sentince is ambiguous without some context). What it could mean is: don't drive the horizontal/vertical sync lines at speeds beyond what your monitor is specified for (common sense, really). A typical modern TV horizontal stage will probably be unharmed by a signal that's way out of range (though that's certaintly no guarantee). Eg, plugging a high definition video signal into a normal old TV usualy doesn't end the TV's life prematurly. Running just a bit out of range (say, a 17KHz horizontal signal) for a long period of time wouldn't be a good idea and it's possible that it could shorten the life of the components in the TV's horizontal output stage. I suspect the typical failure due to this kind of abuse would be something relatively minor like a blown horizontal output transistor.