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Author Topic: Question about hacking a Dreamcast VGA box  (Read 1235 times)

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iscariot

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Question about hacking a Dreamcast VGA box
« on: September 07, 2010, 11:27:36 pm »
Is is possible to hack a Dreamcast VGA box to take an arcade RGB signal and output to a standard 30khz VGA?  I'd like to use this large 21 inch monitor that I have that syncs down to standard 30khz vga, and I've got like 2 extra dreamcast vga boxes.  Has someone done this before?

MonMotha

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Re: Question about hacking a Dreamcast VGA box
« Reply #1 on: September 07, 2010, 11:34:21 pm »
No.  That's not how the Dreamcast VGA box works.  The Dreamcast VGA box actually tells the Dreamcast to output 31kHz VGA timed video since it was capable of doing so, and all games support it.  It doesn't actually do any conversion.

iscariot

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Re: Question about hacking a Dreamcast VGA box
« Reply #2 on: September 07, 2010, 11:36:32 pm »
Crud ok.  I was hoping to be able to put one of these boxes I have to some use....What about the REDANT component->VGA converter?  I've got one of those sitting around here too that I never got around to using.  Would one of those component->vga units work for this?

MonMotha

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Re: Question about hacking a Dreamcast VGA box
« Reply #3 on: September 08, 2010, 09:43:27 am »
From what I can gather, that product is just a colorspace transcoder.  All it does is turn YPbPr into RGB.  No video scaling would be applied.  Thus, scanrate in = scanrate out.  If you feed it 480p YPbPr component, you'll get VGA compatible RGB out.  If you feed it standard res 15k 480i component, you'll get standard res 15k RGB out.

What you need is an upscaler.  They exist. http://www.arcademvs.com/ARCADE_ACESSERIOR.htm has one as product A-24.  The exact same board (it's the only one I've ever seen just with a billion different names on it, as is typical of China OEM'd stuff) is available from several other sellers on the internet.

iscariot

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Re: Question about hacking a Dreamcast VGA box
« Reply #4 on: September 08, 2010, 10:29:54 am »
I see it.  I was hoping for something to preserve scanlines.  Oh well.  Ideas where to get one cheap?

MonMotha

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Re: Question about hacking a Dreamcast VGA box
« Reply #5 on: September 08, 2010, 10:41:34 am »
You inherently cannot preserve real scanlines if you change the scanrate.  They wouldn't look right on a small dot pitch PC monitor, anyway (they'd be way too pronounced).

That price *IS* cheap.  You can easily blow several hundred bucks on something like this.  Some poor kid in China probably died to get you one of those at the prices they go for.  I tend to see that board for about the same price ($60-80 incl shipping) pretty much everywhere.

iscariot

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Re: Question about hacking a Dreamcast VGA box
« Reply #6 on: September 08, 2010, 05:48:28 pm »
Ah that makes sense.

I was just asking about the VGA box because I've grabbed close to a dozen of these in my time and I noticed I had one from awhile back that took component in and output vga but I guess that wouldn't work...sigh..I was hoping that I could just hack up something I had around collecting dust.