VOGONS


First post, by keropi

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Hiya!

as per title, what's the deal with the svhs-output that some vgas have? Yesterday I decided to experiment with recording some footage from my ss7 build, nothing fancy just to pass time mostly...
I was always under the impression that svhs/composite outputs would work with low-res DOS stuff but it turns out that wasn't the case. I tried several nvidia agp cards (from riva128 to mx400) and although I could see DOS and text mode stuff via svhs none of the games show any picture. Also tried a savage2000 vga, it behave better (as in showing ALL boot screens) but still no vga/ega output.
Is there a way to make this work under DOS or windows is the only option?

TIA for any info!

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Reply 1 of 6, by PhilsComputerLab

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Hmm very odd.

For me S-Video out worked flawlessly with every game I tried!

When I started my YouTube channel, S-Video capture was what I used for all my videos.

Cards were newer GeForce MX type.

Later I used a VGA to S-Video converter for convenience.

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Reply 2 of 6, by keropi

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strange... maybe the pci tuner I tried to use didn't like the signal?
I also noticed that the resolution at the monitor changed with the svhs cable connected , is this normal as well?

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Reply 3 of 6, by obobskivich

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What are you connecting to the TV out of the video card? As far as the "resolution changed" - what do you mean? Have you tried hooking straight into a compatible TV and seeing what you get? Is there a mis-set PAL/NTSC jumper on some of your equipment?

As far as resolution and whatnot - there isn't a fixed resolution for CVBS or Y/C, and especially with Y/C the card may be trying to send out something that's beyond what your tuner card can handle (usually videocards with Y/C output can do up to 800x600 on them, which some tuners, TVs, etc may not like). Finally, on newer cards, the TV-out may actually be an independent output from the VGA output (e.g. it's a DualView card), and if that's what your card is doing it probably is only supported under Windows (nVidia cards IME don't failover to cloning the primary output to all connectors like ATi cards do).

Also, just as a nit-picky thing: it is not "SVHS out" - it is properly S-Video ("S" for "Separate" not "Super") or Y/C. SVHS is an extension of the VHS standard; they are separate but somewhat inter-related things (calling Y/C "SVHS out" is like calling HDMI "Blu-ray out" if that analogy helps to make sense of it). 😊

Reply 4 of 6, by keropi

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🤣 yeah, correct on the s-video stuff, that damned tuner had svhs on the bracket and somehow I stuck with it.
I use a philips 7134 based tuner, this one is universal as it supports both pal and ntsc. I have verified this and the signal just gets auto-detected.
Maybe it's the signal from the vga that does not work, I haven't tried the output with a tv set.

By resolution change I mean that if the s-video cable is connected I don't get a full-screen display on my lcd (as normal) but rather a centered scaled-down window with the screen's contents. I assume it's because of the scaling to match the s-video output? At any rate, it's not the same as when you don't have a s-video cable connected to something. It's funny to look at dos/bios/text mode apps looking like that.

I'll do some tests with non-nvidia cards, maybe an s3 or something...

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Reply 5 of 6, by Scali

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obobskivich wrote:

As far as resolution and whatnot - there isn't a fixed resolution for CVBS or Y/C, and especially with Y/C the card may be trying to send out something that's beyond what your tuner card can handle (usually videocards with Y/C output can do up to 800x600 on them, which some tuners, TVs, etc may not like).

Not for the input no, the output is generally either 720x480 60i NTSC or 720x576 50i PAL.
The input is resampled with some cheap chip to generate this analog signal. You can also buy these units separately from eg Koenig. You plug an analog VGA in there, and it will output NTSC or PAL composite and s-video signals.
What resolutions are supported depends on the resampler they used, but generally 800x600 and 1024x768 will work, as will everything lower.

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