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Post by gsteemso on Sept 21, 2015 21:56:00 GMT
While the reference to a “John Carlson” does sound vaguely familiar, I have no clue where from. Link please?
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Post by gsteemso on Sept 21, 2015 22:09:04 GMT
There is a common chip now that does RGB to S-Video and Composite. What chip would that be? How does it react to custom scan rates and resolutions such as the VDC can output (e.g. the Risen from Oblivion demo)? If I were designing a solution to the C128 video problem, I’d probably make it output 720p or 1080i HDTV, filling in around the edges with the VDC border colour. That way you’d always have enough pixels to show everything, no matter how out of spec your program sets its video output. If I were going to really do it properly I’d include an option to do fancy processing to mimic CRT colour-blending effects on flat-panel TVs (which are most of them these days).
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Post by TacKer on Sept 22, 2015 0:00:02 GMT
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Post by Pyrofer on Sept 22, 2015 11:29:16 GMT
The AD724. Seems I am not the first to go here (of course!) and this thread sums most of it up, www.sega-16.com/forum/showthread.php?21145-External-RGB-to-S-video-schematicThe difference is they are starting with proper RGBs instead of the CGA. So by adding a CGA to RGB to the start of this circuit you can get CGA to S-Video. Also, don't forget the Amiga A520 Modulator. That turns RGB into Composite
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Post by gsteemso on Sept 25, 2015 3:19:01 GMT
It will be very interesting indeed to see if the AD724 can handle funky video parameters. My thinking was that the ridiculous range of video timings the VDC can output would necessitate doing some sort of custom FPGA solution or the like, but someone (Mirkosoft?) mentioned in another thread that certain commercial units such as the Ambery AV-1 don't choke on, for example, Risen from Oblivion, so I'm probably over-thinking it. (I believe the AV-1 is a VGA encoder, so does not solve the S-Video problem, but it's still an interesting data point. Anybody out there who has one feel like cracking the case to see what chip(s) it uses?)
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Post by hydrophilic on Sept 25, 2015 4:27:10 GMT
Yeah it would interesting to see what AD724 can do. The GBS-8200 and -8220 do VGA conversion, and have several large (64 pin, or so) chips.
The AV-1 has 2 small 14-pin chips, and one medium 24-pin chip, and it generates both S-Video and Composite (the Composite is crap). I would have to remove all the wires, remove the board, and use a magnifying glass to be sure (didn't do that), but after looking at the 24-pin chip for a few minutes with my aging eyes, it looks like chip# BH72386F (88% confidence).
Here's a photo of the board (not in a case)...
The GBS units use a frame buffer, as far as I can tell, which makes them rather picky about frequencies, and also creates a delay. The AV-1 is much simpler... basically a digital to analog converter (well the color is an analog-to-analog converter). So it will handle almost anything... I guess the only thing it couldn't handle is if the horizontal sync was too short for it to generate a proper color burst (but I don't know any software that messes with the H-Sync period). The bigger issue is, probably, if your TV/monitor can sync to strange frequencies.
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Post by mirkosoft on Sept 25, 2015 9:36:22 GMT
Only to results: Don't look at image quality - it was captured by VGA instead HDMI, there is problem only one: colors. I will contact you Robert (Hydrophilic) for explaining me more 'cause you created intensity integration into converter, what maked from 64 interlaced colors real 136 colors. So, nice solutons, I tried so many converters that I have currently little video studio and can capture from SDTV up to HDTV and scale from/to 2K and everything capture with so many sources that I don't want more converters, only any additional solution.
Thank you all.
Miro
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Post by Pyrofer on Sept 25, 2015 16:04:52 GMT
I have a scart to HDMI adapter. I use it with my C128. I have run Risen demo without issue. So if that uses any odd frequencies then it manages those without issue. I should try Mode Mania.
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Post by gsteemso on Sept 25, 2015 18:45:23 GMT
I have a scart to HDMI adapter. Which model was it, how much was it and where do you get one? I've got one of those little passive adapters that runs composite/stereo into a SCART plug; I seem to recall reading that an RGB-to-SCART adapter is not much more complex.
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Post by Pyrofer on Sept 26, 2015 11:03:41 GMT
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