GBS-C and 240p downscale

[The Great Sephiroth]

I read somewhere that GBS-C has problems downscaling RGBHV to 240p and that it better downscales RGBS to 240p, is that true? If it is true, is it a huge problem?

[NoAffinity]

It is true. It does not downscale rgbhv well.

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[strayan]

If it is true, is it a huge problem?

It’s only a problem if you don’t have a sync combiner. Alternatively: use component video.

[atohmdiy]

My GBS eat some horizontal pixel when downscale. I cannot get these pixel back even with playing with the scaling control.
I am asking myself if i am alone with this and if there is a way to correct it ?
I am using the "passive sync combiner" circuit you can find in retrorgb in the GBS input and output, i am asking myself if the issue do not come from here.

[Bassa-Bassa]

My GBS eat some horizontal pixel when downscale. I cannot get these pixel back even with playing with the scaling control.

Do you mean it goes from 640x480 to 320x240 instead of 640x240? A passive sync combiner hardly has to do with something like that.


As for OP's question, there's a recent compilation in the global GBSC thread here with some models apparently supporting RGBHV input without issues when downscaling.

[atohmdiy]

No i mean there is a part of the horizontal screen that is lost. If i try to play with the scaling there is only crap beyond a certain point. So instead of having for exemple 320x240, i get 280x240 or something.
I made two quick pick, you see the game's interface is eaten on the side.

Spoiler

[NoAffinity]

^yes, that happens. It might be due to being a 3:2 source instead of 4:3. Not completely sure but it is common.

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[atohmdiy]

I'm a not sure. Yes most console will output 720x480, but i also try it with a PC configure at 640x480 and i still have the same issue.

[Bassa-Bassa]

I don't know even which game is the second picture, but Valfaris' graphics are natively 640x360. there's a possibility that if you set Windows output at 640x480, the graphics for this game get upscaled to 853x480, to fill the vertical resolution. Horizontally they just get cropped because of the vertical upscaling forcing the equivalent horizontal scaling. Basically, the game wasn't even tested at 640x480 (which is a shameful irony, given its aforementioned native frame). Or maybe you should just check the game's internal video options.

The question here anyway would be why are you downscaling to 240p a game way over that spec.

[BazookaBen]

Yeah, I don't see why people are wasting their time with GBS-C or Corios when most of these games are available on PC. You don't need a downscaler at all, you just run them at native resolution through CRT Emudriver.

The tricky part is finding the native resolution, but that's fairly easy to do just by running the game windowed at 1x scale, then opening Special K to find what that resolution is. Then you make that as a custom resolution

[atohmdiy]

Both image are from the N Switch 480p output, that is 720x480. Second game is the best beat them up ever : Mother Russia Bleed.

In PC all you get is 16/9 resolution in 90% of the games. 4/3 is available indeed but is unplayable with big black bar on top and bot. Valfaris especially is a good example of that.
With the Switch outputting 480p, you have a proper 4/3 version of these game. When i mean proper, it's not "proper" in the sense that these game stay native 16/9, but at least the interface and resolution are well crop.
That is why i use my Switch if i want to downscale a game to play in 240p 4/3. Some games are perfect in 240p downscaled, like Bloodstained curse of the moon for example.

Here it was just example, i don't play valfaris in 240p. I knew it is a 360p game, some detail are clearly lost in 240p.
I play it in my PC CRT in 480p from my Switch. And in this case there is no issue with the lost pixel on the side, only with the GBS.

Again i also try with a pc set to 640x480. Would be logical that the 720x480 was the source of the issue, but no.
I can also report that there is no issue either with the gbs set in pass-trough. So it's clear this is the downscaling process that crop the game horizontally.

It seems strange i am alone to have this issue. I saw in a few 480p source and i tried with 3x different modded GBS.

[BazookaBen]

That's why it helps to have a 16:9 toggle on your CRT. You have your PC set to output a proper 16:9 resolution (like 426x240) and then you flip your TV to 16:9 letterbox. It compresses the 240 lines to the right place

As I've done here with Blaster Master Zero 3 (432x243 IIRC)

Spoiler

[atohmdiy]

It's up to everyone preference i guess. I only have 20' pro crt, i don't want a zoom out 16/9 image like this with black bar.

And in most of the game i tried, the 4/3 cropping do not impact gameplay.

[BazookaBen]

It's up to everyone preference i guess. I only have 20' pro crt

A lot of PVMs have a 16:9 button. And for ones that don't, you can use the service menu to change the geometry from the "underscan" button to a 16:9 view.

I mean, black bars are just electrons not hitting glass. I don't see why people are concerned about something that doesn't exist.

If you have the lights out in your room, the unlit glass, or "black bars" would disappear and blend in with the rest of the darkness in the room

And most games do need the full view. I don't think Bloodstained CotM is playable with the sides cropped off.

[NoAffinity]

@atohmdiy you're not alone. I dont think I've ever downscaled anything with gbs-c that didnt have some horizontal information loss. It's a fun feature but far from perfect. I want to say with retrotink 5x I've had similar results with its downscaling and the only title I've tried through rt5x - ultra street fighter 4 via xbox 360 component output @ 480p.

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[atohmdiy]

It's up to everyone preference i guess. I only have 20' pro crt

A lot of PVMs have a 16:9 button. And for ones that don't, you can use the service menu to change the geometry from the "underscan" button to a 16:9 view.

I mean, black bars are just electrons not hitting glass. I don't see why people are concerned about something that doesn't exist.

If you have the lights out in your room, the unlit glass, or "black bars" would disappear and blend in with the rest of the darkness in the room

And most games do need the full view. I don't think Bloodstained CotM is playable with the sides cropped off.

My two pro monitor do not have 16/9 function, and even then i won't use it. I don't want 16/9 zoom out gameplay with black bar. If i want to play a game in 16/9, i'd use a 16/9 display. For me the Switch is a blessing to have a proper 4/3 output in the vast majority of it's port.

I finish Bloodstained CotM downscaled in 4/3 240p and this is gorgeous. This is one of the very few that is "perfect", many others have issue with unreadable text etc.

@atohmdiy you're not alone. I dont think I've ever downscaled anything with gbs-c that didnt have some horizontal information loss. It's a fun feature but far from perfect. I want to say with retrotink 5x I've had similar results with its downscaling and the only title I've tried through rt5x - ultra street fighter 4 via xbox 360 component output @ 480p.

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Thank you for the confirmation. It's no big deal but i wanted to know if something could be done, i suppose we need to live with it.
So you are saying the issue is the same with Retrotink ? I don't know if we'll get a proper downscaler one day. At least the GBS cost 20 box, i don't see myself buying a Retrotink that cannot even do better.

[Bassa-Bassa]

Both image are from the N Switch 480p output, that is 720x480. Second game is the best beat them up ever : Mother Russia Bleed.

In PC all you get is 16/9 resolution in 90% of the games. 4/3 is available indeed but is unplayable with big black bar on top and bot. Valfaris especially is a good example of that.

As you mention, everything is up to everyone's preference in the end, mate, but weird preferences are still weird preferences, and you're trying to solve a non issue here derived from those. What you're doing is not different to that disgraceful habit of stretching 4:3 games for a 16:9 display. If you mean big black bars on top and bottom makes the picture too tiny for you on a 20-inch monitor to the point of being "unplayable", you're just too far away from it when playing. This may sound silly, but just get closer when playing these. And actually do try it - going one day from a big display to a smaller one has the immediate effect of turning your mind away. Otherwise, you're just ruining the visuals and how the game is played, as you yourself are undergoing.

With the Switch outputting 480p, you have a proper 4/3 version of these game. When i mean proper, it's not "proper" in the sense that these game stay native 16/9, but at least the interface and resolution are well crop.

That is why i use my Switch if i want to downscale a game to play in 240p 4/3. Some games are perfect in 240p downscaled, like Bloodstained curse of the moon for example.

Here it was just example, i don't play valfaris in 240p. I knew it is a 360p game, some detail are clearly lost in 240p.
I play it in my PC CRT in 480p from my Switch. And in this case there is no issue with the lost pixel on the side, only with the GBS.

It's not just that "some details are lost", it's that you're ruining in the worst possible way 2D graphics. You're, first off, upscaling 360 lines up to 480, then downscaling them to 240p, and then cropping the frame horizontally to display just about 70% of the whole picture. It's totally nuts, mate. Particularly if you do have a PC CRT and a PC, and assuming the game on Windows allows a proper 640x360 display (I thought it didn't at first because you didn't mention your pics were from the Switch version).

Curse of the Moon is natively 427x240 (moreover, it seems to actually use an active frame of 400x240), so it's natural the result is way better than with 640x360 graphics at 240p. As BazookaBen mentions, knowing beforehand which resolution the graphics are natively is mandatory, then you'll likely understand that yours is a non issue. 16:9 games are never ever meant to be displayed by using the whole vertical frame of a 4:3 display.

[atohmdiy]

Both image are from the N Switch 480p output, that is 720x480. Second game is the best beat them up ever : Mother Russia Bleed.

In PC all you get is 16/9 resolution in 90% of the games. 4/3 is available indeed but is unplayable with big black bar on top and bot. Valfaris especially is a good example of that.

As you mention, everything is up to everyone's preference in the end, mate, but weird preferences are still weird preferences, and you're trying to solve a non issue here derived from those. What you're doing is not different to that disgraceful habit of stretching 4:3 games for a 16:9 display. If you mean big black bars on top and bottom makes the picture too tiny for you on a 20-inch monitor to the point of being "unplayable", you're just too far away from it when playing. This may sound silly, but just get closer when playing these. And actually do try it - going one day from a big display to a smaller one has the immediate effect of turning your mind away. Otherwise, you're just ruining the visuals and how the game is played, as you yourself are undergoing.

With the Switch outputting 480p, you have a proper 4/3 version of these game. When i mean proper, it's not "proper" in the sense that these game stay native 16/9, but at least the interface and resolution are well crop.

That is why i use my Switch if i want to downscale a game to play in 240p 4/3. Some games are perfect in 240p downscaled, like Bloodstained curse of the moon for example.

Here it was just example, i don't play valfaris in 240p. I knew it is a 360p game, some detail are clearly lost in 240p.
I play it in my PC CRT in 480p from my Switch. And in this case there is no issue with the lost pixel on the side, only with the GBS.

It's not just that "some details are lost", it's that you're ruining in the worst possible way 2D graphics. You're, first off, upscaling 360 lines up to 480, then downscaling them to 240p, and then cropping the frame horizontally to display just about 70% of the whole picture. It's totally nuts, mate. Particularly if you do have a PC CRT and a PC, and assuming the game on Windows allows a proper 640x360 display (I thought it didn't at first because you didn't mention your pics were from the Switch version).

Curse of the Moon is natively 427x240 (moreover, it seems to actually use an active frame of 400x240), so it's natural the result is way better than with 640x360 graphics at 240p. As BazookaBen mentions, knowing beforehand which resolution the graphics are natively is mandatory, then you'll likely understand that yours is a non issue. 16:9 games are never ever meant to be displayed by using the whole vertical frame of a 4:3 display.

If you have red what i said i already said these quick screenshot are only for example, i don't downscale 360p game to 240p. Only 240p native games like Curse of the moon.
If we follow you a 360p pc game shouldn't be played in any CRT i suppose. The only option in such Pc version of these games is 480p and it's an uneven scaling, so playing it in PC with crtemudriver is already a bad solution. There is no crt that i know of that can do 360p 16/9, these game were targeted for 720p/1080p with 2x/3x scaling. And even then i doubt there is an option to run them at the true native resolution without scaling. So to play them in a CRT you need a BVM D24 at 720p. Too expensive for me, and all the point to play these retro inspire game in a crt is the scanline look. 480p is the maximum in that regards.

I try the PC port of Valfaris at 480p and the zoom out look with big black bar is looking like crap. You know what ? With my Switch it's exactly the same uneven scaling (that is done very well in my opinion), but with the right cropping for 4/3. And i don't see how cropping the side "destroy" the 2d art. It's like playing a 16/9 hack of a classic 4/3 240p game and say the original version destroy the graphics because you don't have the expend field of view.

I know exactly what you will say "these game were design to be in 16/9 blabla". Except that this 480p 4/3 mode is a condition to port games to the Switch API. These are official version of the games and if a developer found that the game is unplayable, they still can refuse the 4/3 cropping and do like all these PC port and zoom out the 16/9 with black bar. There is games in the Switch library that do this, and they look like absolute crap in 480p. Better to play these in 720p and a 16/9 display.

[Bassa-Bassa]

If you have red what i said i already said these quick screenshot are only for example, i don't downscale 360p game to 240p. Only 240p native games like Curse of the moon.

I had, but your other example, Mother Russia, was also above 240p (seems to be 480x270), so I don't really know if you know what you're doing. This is obviously a case-by-case subject - some games will get the HUD cropped, some will be kind of "playable", etc., so using two bad examples to ask about it just makes you wonder. For 427x240 and the likes, Windows version of the games, 15khz CRT and Windows set at that resolution by way of CRT Emu Driver or similar and then get the proper aspect ratio with the monitor's geometry settings or the 16:9 switch.

If we follow you a 360p pc game shouldn't be played in any CRT i suppose. The only option in such Pc version of these games is 480p and it's an uneven scaling, so playing it in PC with crtemudriver is already a bad solution.

I can't tell with certainty about Valfaris particularly, but my proposal is indeed to use a 4:3 PC CRT at 640x360 without any scaling involved. Many games natively at this resolution allow it either, by regular settings (640x480, no scaling) or by brute forcing it somehow. Granted you aren't getting full-screen graphics, but again, you should not.

There is no crt that i know of that can do 360p 16/9,

Full-screen, you mean? Likely there're not. You can use an ordinary CRT monitor at 640x480 with black bars on top and bottom, though. If you prefer size and don't mind filterless interlacing, you can even use a 15khz CRT. Even if there's no 640x480 option without any scaling for a particular case, you always can use a 16:9 HD display and simulate the CRT effect with a scaler program. Anything is better than cropping the frame, whichever the game.

I try the PC port of Valfaris at 480p and the zoom out look with big black bar is looking like crap.

You should make sure that you're setting it properly. And then Windows. There's a possibility that this game still scales the picture at 640x480 no matter what as I mentioned in my first reply to you, but then there're external tools to achieve it.

You know what ? With my Switch it's exactly the same uneven scaling (that is done very well in my opinion), but with the right cropping for 4/3. And i don't see how cropping the side "destroy" the 2d art. It's like playing a 16/9 hack of a classic 4/3 240p game and say the original version destroy the graphics because you don't have the expend field of view.

When I said "ruining" I was talking about your Valfaris example, where the graphics were also scaled twice. But, yeah, in the end, just cropping (or expanding) the intended active area is somehow destroying the visuals in 2D games and more importantly, altering how the game should be played.

I know exactly what you will say "these game were design to be in 16/9 blabla". Except that this 480p 4/3 mode is a condition to port games to the Switch API. These are official version of the games

Well, if that justifies it enough for you even if you're finding out that the games are clearly not implemented when cropped, be my guest. I was just trying to help you out.

[Quris]

It is true. It does not downscale rgbhv well.

What exactly is he doing wrong?

If it is true, is it a huge problem?

It’s only a problem if you don’t have a sync combiner.

Why do you need a sync combiner when if you have BNC inputs? Separate H and separate V on PVM?

Planning to purchase a GBS-C and I can't figure out if the GBS-C converts the signal from PC VGA (RGBHV) to RGBs? Is it possible to customize this in the GBS-C settings?

[SuperSpongo]

You need a sync combiner on the input side, because the GBSC does not handle seperate sync well when you want to downscale to 240p.
I tried this with my Dreamcast and Metal Slug 6.

[BazookaBen]

Planning to purchase a GBS-C and I can't figure out if the GBS-C converts the signal from PC VGA (RGBHV) to RGBs? Is it possible to customize this in the GBS-C settings?

Why would you do this instead of CRT Emudriver? With Emudriver you can have your PC actually output 240p RGBS, with no need to scale.

[Quris]

You need a sync combiner on the input side, because the GBSC does not handle seperate sync well when you want to downscale to 240p.
I tried this with my Dreamcast and Metal Slug 6.

KENZEI SYNC COMBINER will do the trick?

Planning to purchase a GBS-C and I can't figure out if the GBS-C converts the signal from PC VGA (RGBHV) to RGBs? Is it possible to customize this in the GBS-C settings?

Why would you do this instead of CRT Emudriver? With Emudriver you can have your PC actually output 240p RGBS, with no need to scale.

Emudriver requires older video cards. I would like to run, for example, dolphin emulator or some other heavy 3d graphics.

[BazookaBen]

Emudriver requires older video cards. I would like to run, for example, dolphin emulator or some other heavy 3d graphics.

Emulators mostly run on the CPU. A r5 240 or 430, as an example, would be able to handle 960p downscaled to 480i just fine. Though I haven't messed with Ubershaders too much I think they do shift a lot to the GPU.

An alternative is just to put the Radeon card in a secondary slot, and for Dolphin, keep your main card as the rendering GPU. Just use the Radeon for output.

Because if you intend to play any games at 240p, Emudriver is a much better option. Because there's so much variability in horizontal resolution between arcade games, console games, and modern 240p pixel art games.

[Quris]

Emudriver requires older video cards. I would like to run, for example, dolphin emulator or some other heavy 3d graphics.

An alternative is just to put the Radeon card in a secondary slot, and for Dolphin, keep your main card as the rendering GPU. Just use the Radeon for output.

How do I do that? This is the first time I've heard of it. Is there any guide?

I have just an R7 240 from an old computer. I can plug it in, but I also have an HDFury. Wouldn't it be easier to connect to the PVM 5BNC through it? Will that work?

About GBS Control. Wouldn't 640x480 be enough for most PC games? Why do I need to scale games up to 960p? Or is it just for cases when 640x480 resolution game is not supported? How widespread is this problem that there is no 640x480 resolution?

[BazookaBen]

How do I do that? This is the first time I've heard of it. Is there any guide?

I have just an R7 240 from an old computer. I can plug it in, but I also have an HDFury. Wouldn't it be easier to connect to the PVM 5BNC through it? Will that work?

You can set the rendering GPU for particular games in the "graphics" menu in Windows 11 (and maybe 10).

But you only need to do this in games where your r5 240 can't handle the load. Dolphin at 480i will be fine on a r5 240. The one caveat being Ubershaders, I'm not sure how well they run on a weak GPU at low res

your r5 240 has analog RGB on the DVI-I port. So you just use that to go to your PVM. Enable composite sync in Emudriver settings (as opposed to separate H/V sync)

For PVMs you want to make sure all resolutions have positive polarity for H and V pulses

Why do I need to scale games up to 960p?

I'm talking about downsampling (AKA supersampling) 960p to 480i, just to get better anti-aliasing and overall picture quality. Specifically for 3D games, not for 2D pixel art games and the like.