component to vga

MKE · Post by **MKE** » Sat Jul 17, 2004 8:58 pm

does anyone have one/know how to make one/have an idea on how to make one?

i was thinking about making a composite to vga but then i was thinking....

instead of converting the crappy composite, what about making a component/rgb to vga converter.. that way i can have 480p, 540p, and 720p displayed on my monitor...

does anyone have any ideas...

what i was thinking was hooking the rgb + and - signals into the appropiate spots on the vga adapter, then getting the sync seperator chip (do get teh h and v sync) and then put them in the appropiate spots,

i dont think that will work jut because it sounds to easy, but does anyone have some idea of how to ake one?

Marvin · Post by **Marvin** » Sat Jul 17, 2004 11:41 pm

The Dreamcast already can generate a true VGA signal. The R, G, B, HSYNC, and VSYNC signals are present at the A/V connector. All that is needed is to short pins 6 and 7 to ground, that enables VGA mode.

MKE · Post by **MKE** » Sun Jul 18, 2004 1:04 am

it's not for the dc... although i could use it for that, i plan on useing it for the xbox, gc, and saturn mainly...

Ex-Cyber · Post by **Ex-Cyber** » Sun Jul 18, 2004 10:36 am

Well, first of all, VGA is just RGB with separate sync and particular timing ranges. If the console cannot produce RGB at VGA-compatible timings, you have to use a scan doubler; this is a device that buffers the video signal and generates two lines on the output for every 1 line on the input, doubling the horizontal scan rate (TV scan rate is 15.75KHz, the vast majority of VGA monitors will not take a scan rate below 31.5KHz). I'm not aware of any free scandoubler designs. In principle it's just a matter of having an ADC, some buffer RAM, a DAC, and a circuit to generate the RAM control signals and output sync. In practice it's probably a good bit more complex than that.

As for doing component -> RGB/VGA, that requires a device called a transcoder, basically an analog transcoder consists of a handful of video op amps wired to convert the color space. I know of one free transcoder design, but it converts the other way (RGB/VGA -> component). Still, it should give you a basic idea of what is involved in the device.

If you were to build a scan doubler, it might be cheaper to transcode digitally inside the scan doubler since you'd already have the video in a digital form. You may even be able to get a video ADC that essentially does the conversion for you by converting it to CCIR 601. If you're still interested in pursuing the project after reading all that you should probably check out Analog Devices.

Marvin · Post by **Marvin** » Sun Jul 18, 2004 10:42 am

I built one for my Xbox last year. It works with 480p, 720p, and 1080i. I stuffed my notes in a folder somewhere. I could scan them and e-mail them to you. I got a lot of help from guys at xboxhacker.com's forums. I used a few ideas from other people's projects to help me get started.

MKE · Post by **MKE** » Sun Jul 18, 2004 12:54 pm

yeah, ive seen that pic b4 Ex-Cyber, (well, not that one but ive seen similar)

i was just going to buy one from ebay for like 50$, and since i had a lot of time ive been researching (well, googling)about how it's done and stuff.

and marvin, that would be cool if you could scan them and send them to me... my email is:

MKEmodz@gmail.com

aisupikku · Post by **aisupikku** » Mon Jul 19, 2004 11:41 pm

Excuse me; Ex-Cyber? I was wondering if you would be able to answer a question... It was sort of brought up in a topic in Dreamcast Discussion, and, it seems that you might know exactly what's up!

Here's the question: Is that free transcoder schematic you referenced the best way to get color-difference component out of the Dreamcast? I was thinking that there must be a better method, since, given the wide variety of signals output by the DC, there might be less conversion involved... But I suppose, more importantly: Would there be any benefit to converting the signal (to color-difference component) to use with a non-progressive scan television instead of simple S-video?

I've been trying to figure out how to do it (though I have very little knowledge in this area), and I've asked around at a few video format forums, but since they're not quite familiar with the DC (and moreso care not to answer any questions), I haven't heard anything solid yet, so, I've contined to try to figure it out on my own... So, even a little "yay" or "nay" towards the idea would be greatly appreciated! I would regard your opinion very highly...