thatguy
Posts: 2
Joined: Sat Oct 04, 2014 1:17 pm

Sega Dreamcast VGA to Component mod

Sat Oct 04, 2014 1:40 pm

Alright, I have a crazy idea. Why not build a mod that takes the crisp, clean...but not entirely functional VGA signal from a Sega Dreamcast (seeing that VGA is phased out on TVs now, and pretty soon computer monitors) and bring it over to a more contemporary connection like Component (HDMI is out of the question for reasons). Now I have done a few RGBs to Component mods, several internal for SNES and N64 (because RGB is not a contemporary format for us in North America).

But doing Enhanced Definition 480p to Component is not an easy task. I have little experience with FPGAs (which is what I assume I would need to do the conversion) and coding.

Has anyone attempted this, is this just a madman's dream? How do I get started?

meneerbeer
Posts: 35
Joined: Wed Aug 27, 2014 8:43 am

Re: Sega Dreamcast VGA to Component mod

Sun Oct 05, 2014 3:26 am

This should be possible. I do not know whether it is possible to tap the digital video signal somewhere, but I suppose it would be in RGB format. Then with an FPGA you would have to convert it to, I think, YPbPr format.

If there is no way to tap the digital video signal, you would have to sample the analog RGB lines. This would degrade the quality a bit. :(

I believe the internal VGA mods for the Dreamcast require a switch to turn on VGA. I am not sure if VGA works with every game, I do not think it does. I suppose if you turn on the switch, the Dreamcast will output 480p, which would be the only signal that really qualifies for the VGA spec. I am not entirely sure about this, but I suppose 576p is not an option, since a lot of monitors will not take it.

So if what I am saying above is correct and you apply the component mod, you would get 480i or 576i when the switch is not turned on and 480p when you turn it on?
But doing Enhanced Definition 480p to Component is not an easy task. I have little experience with FPGAs (which is what I assume I would need to do the conversion) and coding.
What would make this different from doing it for the N64 and SNES?

thatguy
Posts: 2
Joined: Sat Oct 04, 2014 1:17 pm

Re: Sega Dreamcast VGA to Component mod

Sun Oct 05, 2014 9:54 am

This should be possible. I do not know whether it is possible to tap the digital video signal somewhere, but I suppose it would be in RGB format. Then with an FPGA you would have to convert it to, I think, YPbPr format.

If there is no way to tap the digital video signal, you would have to sample the analog RGB lines. This would degrade the quality a bit. :(

I believe the internal VGA mods for the Dreamcast require a switch to turn on VGA. I am not sure if VGA works with every game, I do not think it does. I suppose if you turn on the switch, the Dreamcast will output 480p, which would be the only signal that really qualifies for the VGA spec. I am not entirely sure about this, but I suppose 576p is not an option, since a lot of monitors will not take it.

So if what I am saying above is correct and you apply the component mod, you would get 480i or 576i when the switch is not turned on and 480p when you turn it on?
But doing Enhanced Definition 480p to Component is not an easy task. I have little experience with FPGAs (which is what I assume I would need to do the conversion) and coding.
What would make this different from doing it for the N64 and SNES?
Two sync lines, and I don't know of any chips like the BA7230LS which take a RGB signal and convert it to Component so I assume an FPGA would be necessary.

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