VOGONS


Voodoo2: video is offset

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Reply 20 of 27, by maxtherabbit

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mrfusion92 wrote on 2022-06-15, 18:01:

Thank you, sadly the ossc didn't arrive today. Hope tomorrow.

Do you have direct experience with the Voodoo2 + OSSC? Because I can't find much information online.

I do, my main gaming retro box has V2 SLI going -> extron matrix -> OSSC -> plasma TV.

Reply 21 of 27, by leonardo

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mrfusion92 wrote on 2022-06-14, 11:37:
Hi, do I have a faulty Diamond Monster 3D II? As you can see in the screenshots the screen screen is offset to the right. […]
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Hi, do I have a faulty Diamond Monster 3D II? As you can see in the screenshots the screen screen is offset to the right.

Right now I'm capturing the PC throught a VGA-HDMI converter, but the issue appears also with a VGA monitor connected directly. It is a LCD tho, I don't have a CRT.
It happens only with games that use the Voodoo, and I had to set the refresh rate to 75Hz otherwise the screen was offset to the top too.

glquake.pngnfs2.png

Seems someone didn't grow up with analog tube monitors.

This is perfectly normal and expected behavior. Your monitor (LCD or CRT) when connected to an analog source will store settings such as the geometry adjustments into it's own internal memory. These settings are refresh rate specific. Because most systems have a single video card, you only ever really have to adjust the image once per resolution/color depth once you've set your desired refresh rate.

The thing that happens with the Voodoos is that the Voodoo will pass through the signal from your actual video card directly to the monitor, but hijacks it when 3D-acceleration is being used. Because the Voodoo is a different card to your main video card, the signal will differ slightly resulting the monitor adjustments being "off" to what ever small variance there is in the signal.

The way I resolved this back in my Voodoo1/2-days, was that I set the Voodoo to use a different refresh rate to my desktop. For example, I might have my main video card show my desktop at a resolution of 800x600 and a refresh rate of 85 Hz. I would then set the Voodoo to use a refresh rate of 75 Hz at the same resolution.

Because the monitor keeps the adjustments per refresh rate, this allowed me to always keep my preferred adjustments without having to constantly change them when the signal got swapped between the cards.

With DVI and later digital standards, none of the location/geometry related adjustments are saved by the monitor, because they're not necessary any more (the monitor will always align pixels perfectly, 1:1).

[Install Win95 like you were born in 1985!] on systems like this or this.

Reply 22 of 27, by mrfusion92

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Yes, I indeed lived only the last days of the CRT era. The first family PC (a Pentium II) had a 15'' CRT screen (don't remember the brand) after we got a 17'' Compaq. After some years (I think around 2005) my father bought a Sony LCD 19'' with a resolution of 1280x1024. Oh boy I still remember the day when we switched, it was truly a magnificent screen. Never touched a CRT again after.

Also none of the family PC were made for gaming really, nor I was so interested in that time to games (but I learned VB for Excel at 8\10 years old) so I'm not so aware of this issues with refresh rates/back porch/timings.
I'm catching up with everything now!

Reply 23 of 27, by leonardo

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Yeah... tube monitors feel like steam engines do nowadays, obsolete, but yet somehow still beautiful.

This weirdness with the image adjustments is very specific to the 3Dfx add-on card (or separate "3D-accelerator") solution. Starting with the Voodoo3 (which has the more standard video card design, with integrated 2D/3D-features) you would no longer have to make separate adjustments on your monitor for 2D/desktop-mode and 3D-accelerated mode.

[Install Win95 like you were born in 1985!] on systems like this or this.

Reply 24 of 27, by mrfusion92

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Already in love with the OSSC. Of course it fixed and improved everything. I'm already certain that I will keep it.

maxtherabbit wrote on 2022-06-15, 16:54:

This is 100% normal. The V2 has different backporch timings. It is what it is.

EDIT: I see you bought an OSSC. In order to get truly good results with the OSSC you will need to feed the syncs to AV3 and the colours to AV1 or 2. This is due to the piss poor low pass filtering on AV3. V2 very much needs LPF to look good digitised.

Additionally, you will need to make separate profiles on the OSSC for the voodoo and the primary 2d card. Otherwise you will still have the same offset issue.

I've created the separate profiles, switch them with the remote is really easy. And for now the quality I get using only AV3 is enough, I will probably in the future try to create the Y-cable for separate RGB and sync signals.

Everyone thanks for all your posts and help. And sorry for all the fuss!

Reply 25 of 27, by Gamecollector

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IMHO Voodoo2 uses wrong timings for the horisontal backporch.

P.S. Glide2x sources for Linux, glide2x\svg\init\sst1init.h, SST_VREZ_640X480_60:
38, /* hBackPorch */
The correct value is 48.

Asus P4P800 SE/Pentium4 3.2E/2 Gb DDR400B,
Radeon HD3850 Agp (Sapphire), Catalyst 14.4 (XpProSp3).
Voodoo2 12 MB SLI, Win2k drivers 1.02.00 (XpProSp3).

Reply 26 of 27, by maxtherabbit

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Gamecollector wrote on 2022-06-20, 20:33:
IMHO Voodoo2 uses wrong timings for the horisontal backporch. […]
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IMHO Voodoo2 uses wrong timings for the horisontal backporch.

P.S. Glide2x sources for Linux, glide2x\svg\init\sst1init.h, SST_VREZ_640X480_60:
38, /* hBackPorch */
The correct value is 48.

You're saying you can adjust the backporch with an SST define?

Reply 27 of 27, by Gamecollector

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SSTV2_BACKPORCH=0x21002E?
The trouble is -- this variable affects all resolutions and all refresh rates...

P.S. http://darwin-3dfx.sourceforge.net/voodoo2.pdf, part 13. Looks like the hardware adds 2 CLK to the hBackPorch value in the register...

Asus P4P800 SE/Pentium4 3.2E/2 Gb DDR400B,
Radeon HD3850 Agp (Sapphire), Catalyst 14.4 (XpProSp3).
Voodoo2 12 MB SLI, Win2k drivers 1.02.00 (XpProSp3).