All-in-one component video solution

Discussion in 'Sega Dreamcast Development and Research' started by Samson, Nov 19, 2011.

  1. Samson

    Samson Active Member

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    Yes. Luckily VGA and RGB (Scart) are similar, both use the RGB lines, but VGA uses H/V-Sync and Scart uses C-Sync. On Dreamcast both H/V-Sync and C-Sync seem to be available at the same time.
    The problem is (at least for my TV) that the VGA input doesn't like 15 kHz interlaced pictures and Scart doesn't like 31 kHz VGA signals.
    (Wait a second, weren't there a few games that didn't support scart either?)
     
    Last edited: Jan 20, 2012
  2. Melchior

    Melchior Rapidly Rising Member

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    Nope, I'm pretty sure its either 15Khz or 31Khz. All games must use one or the other.

    IIRC I thought there was a boot disk to force VGA support / disc-header editing tools.

    Also the only games that don't support VGA supposedly sucked ~ :rolleyes:
     
  3. Samson

    Samson Active Member

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    Looks like there are a few games that (depending on region) support only composite... There shouldn't really be a technical reason not to support rgb over scart other than a dodgy header. Seems to be mostly capcom games. Maybe they didn't know that all the cool kids ran their consoles over Scart/RGB?
    Just for amusement I looked what it takes to convert S-Video back into component and multiplex it with the RGB output, but that's far too much effort. Especially because S-Video is different between PAL and NTSC.
     
  4. Samson

    Samson Active Member

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    Okay, small update: it looks like the 7660 output wasn't stable enough, and I was a bit distracted by other projects. I was going to try another DC-DC converter, though I just found out that I got the wrong part delivered. (Oh, and this stuff is a pain to debug without a scope. :) )
     
  5. Fireball haven

    Fireball haven Active Member

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    Nothing is wrong with VGA, though I'd like component for my TV.
    Has anyone cracked one of those scart-to-hdmi boxes open to see which chip does the encoding? And has anyone seen one where you can switch off upscaling? I guess a simple solution would be to put the VGA box logic directly inside, and get it powered from the dreamcast (if it doesn't draw too much current).
    I thought about how to do it for N64, because the data format between display controller and DAC was decoded. So you could write an FPGA design that pretends to be an N64 DAC and generates a DVI or HDMI signal in turn. Though development boards for FPGA with DVI or HDMI out are too expensive IMHO for a pet project.
     

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