240p downscaling test run with GBS-C

[Superior Sephiroth]

So I did a 240p downscaling test run with GBS-C using Windows ME retro PC with Voodoo 2 12MB in SLI and Quake 2/II to Sony BVM:
youtube.com/shorts/We-kTRHzoTM
Not everything went perfectly. The image is perfect only for a split part of a second. After I press button (you can hear the click) on GBS-C "control panel" to "initialize downscaling protocol" then its start doing its "magic" and for a split part of a second I/you can see perfect image but then it goes back to this usual mess. Of course it was test run so not everything was perfect:
1. I may used poor power supply.
2. The input signal was VGA RGBHV (so not RGBS which supposedly GBS-C prefers).
3. Too many/long cables/connections especially from the GBS-C output to Sony BVM input (I will work to simplify that in the future).
Could any of the above be the cause of this (downscaling behavior) or something else caused it? Why white "RGB" was always on the screen on my Sony BVM and never disappeared? What PSU (2.1mm or 2.5mm) does this chinese GBS-C use:
https://ibb.co/dBMP1MM
?

[orange808]

Here's the wiki:
https://ramapcsx2.github.io/gbs-control ... modes.html

I don't know what signal you're feeding. GBS Control only downscales 480p. You say you're using an SLI setup and that makes me wonder. I recall using SLI to get high frame rates for 768p, but you shouldn't need two cards and SLI to get 480p. Are you running 1024x768?

Beyond input resolutions, the GBS Control is well known to be finicky and struggle with many sources. The wiki should have recommendations for power supply. There's also a lot of opportunities for user error when you build a DIY machine.

[Superior Sephiroth]

I set in game resolution to 640x480 and I also tried Diablo II/2 with 640x480 in game and results were the exact same mess (including both Blizzard startup screens) except Diablo II game start menu and saved character select (they were messed up differently; maybe they used different resolution?) but all other screens (including both Blizzard startup screens) and gameplay (in game) were exact same as with Quake 2/II. What is causing this? What PSU (2.1mm or 2.5mm) does my chinese aliexpress GBS-C use? Why does white 'RGB' always stays on?

[NoAffinity]

Gbs-c does not downscale rgbhv

Power supply should be 5v 1a minimum

[Bassa-Bassa]

What result do you expect exactly from games which are way beyond 240p natively anyway? Not saying you're not facing hardware-related issues as well, but wouldn't it be better picking something like Lomax or Maui Mallard for a test run of this?

Gbs-c does not downscale rgbhv

So is that definitely the case for the prebuilt Chinese units with RGBS input as a selling point, as well?

[Superior Sephiroth]

So I tried Dreamcast RGBHV 480p and result was the same. Then I tried SNES RGBS 480i R.P.M. Racing and it worked perfectly and changed flickery 480i to nice and crisp 240p. So the PSU and long cables and too many connections are not a problem most likely. The problem is probably RGBHV (probably I hope) and/or 480p (less likely I hope). Will 480p RGBS through SCART work ok with GBS-C to downscale? Also my other questions still stand:
1. What PSU: 2.1mm or 2.5mm?
2. How to get rid of white RGB on Sony BVM?

[NoAffinity]

What result do you expect exactly from games which are way beyond 240p natively anyway? Not saying you're not facing hardware-related issues as well, but wouldn't it be better picking something like Lomax or Maui Mallard for a test run of this?

Gbs-c does not downscale rgbhv

So is that definitely the case for the prebuilt Chinese units with RGBS input as a selling point, as well?

It is the case for GBSC. The code does not handle downscaling of RGBHV properly.

^@Superior Sephiroth - See two previous comments about GBSC not downscaling RGBHV. It never will no matter how many different RGBHV sources you throw at it. You can do a sync combiner on the output to get RGBS from your RGBHV source, and that may work, but with all the caveats noted by orange808.

Quoting from a thread about OSSC at VGP (they require the same power supply):
You require a unit that outputs DC 5V with at least 1 Amp. The tip must be 2.1 x 5.5mm and centre positive.

[Bassa-Bassa]

So is that definitely the case for the prebuilt Chinese units with RGBS input as a selling point, as well?

It is the case for GBSC. The code does not handle downscaling of RGBHV properly.

Thanks for confirming. So we can't expect the Chinese makers to solve this at some point unless they add an input with a sync combiner (which I thought that was the case for those with RGBHV input as a selling point at least).

What about SOG (from Sony machines), does it behave like RGBS on the GBSC?

Edited - just remembered SOG is reportedly not working either.

[Superior Sephiroth]

So one last thing left:
How to get rid of white RGB letters on Sony BVM?

[NoAffinity]

Actually, I believe the rgbhv downscaling issue is a hardware limitation. If memory serves, it is detailed somewhere within the larger gbsc thread...somewhere in the last 50 pages or so...

If the input is sync combine, then it should work. I installed a sync combiner inside a dreamcast vga box, so that the output is a sync combined rgbs. It works fine with the gbsc downscaling.

I also don't believe the Chinese are doing anything with the firmware and have seen others report that the Chinese units usually ship with an outdated firmware and if you can figure out how to update your particular unit, it will update just fine. That said, they are simply adding hardware to the project's otherwise unmodified base operation.

[Bassa-Bassa]

Another good question is why all? these Chinese devices still come with outdated firmware in 2024, indeed.