Help: Forcing 640x480 resolution PC to BVM via Mimo Genius

[jujukun]

Hi,

I'm trying - without success - to downscale the picture of my PC to 240p on my BVM monitor to run Mame on it. To do so:
- I force the resolution to 640x480 through the Display configuration of the PC
- I connect the PC to the BVM monitor through UMSA (VGA to scart) and Genius II (downscaler)
- The Genius II display is set to RGB ("0")

All I get on the BVM screen is a weird resolution of 1023x760 as shown in the pic below:
http://imgur.com/XdZwvlP

I double-checked on the display configuration of the PC after hooking again the PC on my Eizo monitor via HDMI and it's forced in 640x480. So, I don't understand why the resolution is set on 1023x760 on my BVM...

I'm probably doing something wrong. Anyone can help me? Fudoh maybe?

[Fudoh]

Your BVM receives a 240p signal. The question is what your PC does output to the Genius II. You can access the screen settings while the GII is running, so just go through the resolutions then and see how the resulting image changes. If your PC relies on EDID readings, connecting it to one display, setting it to specific resolution and then connecting to another display won't work, since the PC will change resolutions in between.

[jujukun]

Thx for the input!

I tried your suggestion consisting in selecting resolutions directly on the BVM with the GII connected aaand... unfortunately it doesn't work: it always reinitialize to this 1023*760 display no matter what I do. So I guess you're right with that EDID thing...
So there is nothing I can do about it?

[Fudoh]

My first guess would be that you're changing your canvas size, but the GPU scaling remains active and outputs at XGA.

[jujukun]

I finally managed to set 640*480 on the bvm by toying with Nvidia Control panel. However the GII doesn't downscale it to 240p, that's weird.

[SNK-NEO-GEO]

An option is to look into Groovymame and a supported video card to run games at the native resolution.

[Fudoh]

I finally managed to set 640*480 on the bvm by toying with Nvidia Control panel. However the GII doesn't downscale it to 240p, that's weird.

what does it do instead ? Does your BVM support anything but 15khz ? Your Image box showed a 240p output (despite the MIMO getting a XGA signal from the PC).

[jujukun]

An option is to look into Groovymame and a supported video card to run games at the native resolution.

I actually have a Groovymame setup, dedicated to my candy cab. Don't want to move it from the cab

I finally managed to set 640*480 on the bvm by toying with Nvidia Control panel. However the GII doesn't downscale it to 240p, that's weird.

what does it do instead ? Does your BVM support anything but 15khz ? Your Image box showed a 240p output (despite the MIMO getting a XGA signal from the PC).

It's a BVM 20F1E which only supports 15khz.
I'll post a pic of the display tonight after work, so you can check by yourself.

[jujukun]

An option is to look into Groovymame and a supported video card to run games at the native resolution.

I actually have a Groovymame setup, dedicated to my candy cab. Don't want to move it from the cab

I finally managed to set 640*480 on the bvm by toying with Nvidia Control panel. However the GII doesn't downscale it to 240p, that's weird.

what does it do instead ? Does your BVM support anything but 15khz ? Your Image box showed a 240p output (despite the MIMO getting a XGA signal from the PC).

It's a BVM 20F1E which only supports 15khz.
I'll post a pic of the display tonight after work, so you can check by yourself.

@fudoh
Below the pic of the display I get when I force the resolution to 640x480 through Nvidia display control panel.
http://imgur.com/D3LgMLU

As you can see, if I select the 240p display ("0") on the GII, I get a 640x240 15khz 60hz resolution, which is not right. Normally I should get 320x240. I don't know why the GII doesn't downscale 640 to 320 . Do you have an idea of what's going on?

[Fudoh]

Launch a test pattern with vertical 1-px columns to see what resolution gets output.

[jujukun]

Just to be sure I get your suggestion: I replace 640 px by 1 px and then I launch a test pattern, like this one:
http://www.lagom.nl/lcd-test/display_settings.php

Is this right?

[Fudoh]

You can simply display this one http://pms.hazard-city.de/50grey_1920x1080.gif Doesn't matter that it's oversized, just make sure it's displayed 1:1.

What I'm saying: the info display on the GII likely just tells you about the timing, not what it's actually internally doing with the signal. The OSSC produces a considerably sharper 240p output (on the horizontal) than other scan converters, so I assume the horizontal resolutions gets cut down as well.