Raspberry Pi Resolution settings advice

[Skykid]

Yo techy bros,

I am having a conundrum with Snes resolution in retroarch. My HW is as follows:

Raspberry Pi with emulationstation (irrelevant) running retroarch into two different monitors. One is 800 x 600 LCD, the other 640 x 480 CRT, both via VGA and both 60hz displays. I have a true 640 x 480 scanline overlay and Retroarch global config is set to 640 x 480 default video resolution across all emulators.

Now I don't think the average gamer would notice this, but to my eyes SNES emulation is slightly off in terms of display. Hard to explain, but the pixels appear slightly more 'jagged' and slightly fat in places. I found actually switching off the Integer setting fires the occasional stretched row of pixels (I spotted text at the bottom of Goemon was corrected with integer off) but the overall display is just not quite uniform.

Additionally there's what looks like some kind of V-Syncing error happening with SNES stuff: when the image scrolls or when a sprite moves up and down there's a kind of 'scaling' happening, like a ripple effect over the graphics. There's also a general 'shimmer' on sprite motion and background motion. I've turned off the scanline overlay and it's still there, I've turned off V-Sync and it's still there.

The emulator is SNES 9x 2010

Comparatively Mega Drive emulation is clean as a whistle, as is PCE and most other stuff I've checked.

I've switched video resolution for the SNES through just about everything I can without losing the image, but it just reduces the overall screen size (and off centers it severely) and doesn't seem to solve the problem.

Ideas?

Thanks much!

[FBX]

Well SNES games are typically run at 256x224, which means stretching to fill the screen vertically on say 640x480 wouldn't be kosher. You need a little bit of letterboxing (black bars on the top and bottom of the screen). Also any sort of aspect correction on the horizontal axis will also cause shimmering and misshapen pixels.

So for a 640x480 screen, you'd want the SNES 2x scaled to 512x448, and that's of course going to leave black borders all the way around.

[Skykid]

Well SNES games are typically run at 256x224, which means stretching to fill the screen vertically on say 640x480 wouldn't be kosher. You need a little bit of letterboxing (black bars on the top and bottom of the screen). Also any sort of aspect correction on the horizontal axis will also cause shimmering and misshapen pixels.

So for a 640x480 screen, you'd want the SNES 2x scaled to 512x448, and that's of course going to leave black borders all the way around.

You're the man, man. Looks perfect now, I should have considered checking the native video output, I just thought for some reason Retroarch would have a way of 'automating' it accurately at full screen (even the 2x integer setting is incorrect, stretching vertically to hit the top and bottom of the screen).

I have black borders all the way around, but that's preferable to the display inaccuracy at full screen. Now how do I save retroarch video configurations by emulator - a new challenge awaits.

Appreciate your help FBX.

[Guspaz]

It's still innaccurate, the SNES used non-square pixels, meaning the image was displayed as 4:3 on a TV. As a result, a 2x integer scale on a SNES produces a squashed image as compared to a real SNES.

There may be something you can do with scaling filters/shaders to get the correct aspect ratio without the shimmering problem while maintaining relatively sharp pixels. This description of the Pixellate shader seems promising:

This shader is supposed to appear the same as nearest neighbor (aka "unfiltered"), except with minor corrections when using a non-integer scale that are increasingly less noticeable the higher it is scaled. This shader is very useful to anyone who wants to keep things as sharp as possible without worrying about scale factors. Available in XML and Cg shader formats.

[linko9]

You should be able to eliminate those borders while maintaining the original (lack of) scaling.

I don't have experience with VGA CRTs, but on my PVM I run resolutions of 2560x240 and 2560x224 depending on the system/game. The large horizontal resolution allows identical pixel widths while filling the entire horizontal space, no matter the horizontal resolution of the source. You can do something similar with a VGA monitor:

https://gist.github.com/Monroe88/dbd3e01252afa5c50690

If you have only 640 horizontal pixels, you'll get uneven scaling unless the source H-resolution is 320 or 640, or else you'll need those black bars. However, since CRTs have effectively unlimited horizontal resolution, you can get perfect horizontal resolution that fills the screen no matter the source.

For the vertical resolution, it shouldn't be a problem, though I have an issue with Retroarch specifically (and I'd like to know how this works for you). I'll repost my post from another forum and hopefully someone can help me out with this issue:

I am however having one problem. For consoles that output 224 vertical lines instead of 240 (like Genesis), I can't find a way to display the image without black bars at the top and bottom of the screen (8 pixels each). I have 2560x240 and 2560x224 resolutions defined for my monitor, and in something like MAME, if a game runs at a native vertical resolution of 224, I simply set my desktop to the 224p resolution, run the game, and it takes up the full screen with 1 to 1 line scaling. However in Retroarch, it does something very odd. Upon booting up a core, it actually changes the way the 224p resolution is displayed in such a way that scrunches up the vertical lines, so that 8 black lines are displayed at the top and bottom. As far as Windows is concerned, the resolution is indeed 224p, and if I exit fullscreen mode, the scrunching persists, and my mouse cursor cannot enter those 8-pixel tall black bars. As soon as I exit Retroarch, the scrunching goes away, and the 224p resolution reaches the top and bottom of the screen again. If I enable windowed fullscreen mode, it actually just treats the screen as 240p (overriding the desktop setting), applying ugly scaling to the picture to make it fill the full screen.

This problem happens whether or not I specifically define video_resolution_x and _y in the .ini file. It's really odd. I should note that because I have a custom viewport of 2560x224 set, the displayed image is identical whether my screen resolution is 240p or 224p; both have the black borders. I can of course remedy this problem by going into my monitor's service menu and changing the vertical stretch, but this is pretty cumbersome, and I'd like to avoid this and have it just work like MAME in this regard. Any help would be appreciated!

edit: Oh also, as a generally useful tip, you can use "integer scaling" and a custom viewport in the Retroarch video settings to ensure that both H and V resolutions are a multiple of the native resolution of the machine in question. Just make sure "configuration per core" is enabled, and know that after checking "integer scaling" it won't automatically apply new viewport numbers; you'll have to set those numbers after checking "integer scaling."

[Skykid]

Hey guys,

Thanks for the info. So I spent all evening trying to set up correct resolutions for a ton of consoles based on their native res at 2x scale.

Most of everything from MD to Famicom appears perfectly decent, but there are two that are perplexing:

Neo Geo - looks absolutely crystal clear graphically but I noticed that scrolling backgrounds (Metal Slug for example) have a very slight judder when in motion. No idea what's causing it. It's set at a custom resolution of 2x the Neo Resolution of 308x224 because the 320x224 didn't look quite right (I know there's some debate about the optimal resolution for NG).

But the motion judder is odd.

Second issue is SNES still - even though the pixels are accurate to the point that the shimmering and scaling effects are gone, my 640x480 scanline overlay is appearing 'banded' over sections of flat colour (like background sky). It's faint but definitely there!

@linko9 Pretty much everything is displaying within a black box, that is to say black borders all around - but I don't mind the trade off for an accurate display.

I'm going to sleep now as it's 2am my side of the world, but I'll take a look at your suggestions for getting rid of the borders tomorrow and tell you what I mange find.

@Guspaz Thanks for the info! I tend to favour overlays to keep speeds healthy, but I'll definitely have a look at the shader tomorrow and see if it helps any.

[linko9]

Unless I'm misunderstanding the problem, that "motion judder" can only be eliminated by enabling vsync. Keep in mind vsync will add 1 frame of input lag, HOWEVER you can reduce that somewhat by increasing the "frame delay" setting. Set it as high as your hardware will allow for each system without any slowdown/stuttering.

As for the scanline overlay, is it possible that it's trying to apply the pattern to a 480 pixel tall area, rather than the 448 pixel tall area it should be? That could be causing the problem (crushing a 480 tall effect into a 448 tall window), though I've never used overlays myself.

[Skykid]

Unless I'm misunderstanding the problem, that "motion judder" can only be eliminated by enabling vsync. Keep in mind vsync will add 1 frame of input lag, HOWEVER you can reduce that somewhat by increasing the "frame delay" setting. Set it as high as your hardware will allow for each system without any slowdown/stuttering.

Well V-Snyc is already on. It's not like screen tearing or anything, just a feel that the background isn't completely smooth in motion. I'll test frame delay and other options today and see what I can deduce.

As for the scanline overlay, is it possible that it's trying to apply the pattern to a 480 pixel tall area, rather than the 448 pixel tall area it should be? That could be causing the problem (crushing a 480 tall effect into a 448 tall window), though I've never used overlays myself.

That would make sense I suppose. For some reason I thought the overlay was corresponding to display output of 640 x 480 rather than image dimensions. For example I have adjusted everything I can to native resolution on a 2x scale and haven't noticed the same problem on other consoles... Yet. I'll comb over all this stuff today.

Thanks for your help fellas, much appreciated!

[Skykid]

I think the Metal Slug background scrolling not feeling smooth enough is just my eyes. I tested it at various resolutions and it's the same across the board. Perhaps its the speed that MS's backgrounds scroll that's odd. Other games seemed fine. The frame delay is a great tip though for optimisation, thanks for that.

[WelshMegalodon]

There have been improvements to SNES9x since 2010. The long-awaited v1.54 was released not too long ago, so I'd suggest trying that as well. And I'm sure you already know this, but you're far more likely to have pleasing results emulating Neo Geo in GroovyMAME than in RetroArch.

[Skykid]

There have been improvements to SNES9x since 2010. The long-awaited v1.54 was released not too long ago, so I'd suggest trying that as well. And I'm sure you already know this, but you're far more likely to have pleasing results emulating Neo Geo in GroovyMAME than in RetroArch.

Unfortunately I'm experimenting with the Raspi at the moment and that means I'm stuck with retroarch under emulationstation. To be honest I'm very happy with performance for such a tiny device, it has a huge amount going for it. Retroarch is overcomplicated, but it does enough for me.

I'll make tweaks where possible and try to have it set up optimally. I haven't noticed any real probs with Neo Geo emulation as yet.

[Fudoh]

just a hint: Metal Slug isn't a good benchmark for scrolling, since it's a 30fps title.

[ZellSF]

Another hint: the 240p test suite scrolling grid is the best benchmark for scrolling.

[Skykid]

just a hint: Metal Slug isn't a good benchmark for scrolling, since it's a 30fps title.

Ah right, that might explain it.

Another hint: the 240p test suite scrolling grid is the best benchmark for scrolling.

Sweet, I'll check that out, thanks.

[Skykid]

Today's experimenting:

It's still innaccurate, the SNES used non-square pixels, meaning the image was displayed as 4:3 on a TV. As a result, a 2x integer scale on a SNES produces a squashed image as compared to a real SNES.

There may be something you can do with scaling filters/shaders to get the correct aspect ratio without the shimmering problem while maintaining relatively sharp pixels. This description of the Pixellate shader seems promising

I tried the Pixellate shader and can't see much discernible difference. After scaling the picture to full screen the shimmering and scaling still occurs on moving objects. I tried with and without scanline overlays, and combined with other shaders. No dice. When it's applied on its own at 2x scale I'm struggling to see what it even does graphically tbh.

You should be able to eliminate those borders while maintaining the original (lack of) scaling.

Yet to try this. Today I tried various shader + overlay combos and settled with shader CRT-PI VERTICAL (no idea why this one has horizontal scanlines...?) with all settings at 'don't care' plus 640 x 480 scanline overlay at 40% opacity. Looks quite beautiful, if a little darker than normal. The colours are really rich though.

I'm curious what shader combos you guys use for things actually, if you wouldn't mind sharing - and with the regular CRT-PI shader, is that just meant to look like a cross-hatch mesh? Similar to a hi-res monitor (or possibly like a BVM?) CRT-PI doesn't seem to work with a scanline overlay, it just gets darker overall without showing the scanline increase.

Thanks for your help.

[Guspaz]

I believe that Pixellate is intended to basically be like nearest-neighbour filtering, but with interpolation along pixel boundaries to make the pixel sizes even when using non-integer scaling factors, but I'm speculating. It's possible that 640x480 is just too low resolution for this to work properly.

[Fudoh]

Pixellate is really nice, as it's indeed intended for higher resolutions. Works nicely with 720p on the Pi3 (and great with 1080p on other platforms, but the Pi struggles using the filter at 1080p).

What you need is a filter that keeps the 2x vertical scaling and applies a high integer scaling on the horizontal (e.g. 4x or 5x) followed by a linear downscale to 640 (or 720) pixels. I'm not sure on how the Retroarch filters work, but it should be possible to get the 5x/2x scaling done in the emu settings while a shader takes care of the filtering and down scaling.

[Skykid]

Well at the moment I'm working on a project for a 640 x 480 CRT display, so if Pixellate doesn't work at that resolution that would explain it. The LCD I was testing on has a resolution of 800 x 600, but I haven't tried bumping up the video resolution on the configuration with that one yet.

In the future I'd like to configure a Pi for an HDTV so once I know more about setups I will give Pixellate and other things a go.

I'm using a Pi3 BTW.

I'm still curious about your shader configurations and would be interested to hear some examples.

Fudoh, I read your post 3 times and I'm not 100% sure how to configure all that stuff, but I'll give it a shot if you can break it down for me. I'm new to shaders and shader configurations, a NOOB if you will!

I'm off on holiday a few days from tomorrow but will keep on it when I return.

[Fudoh]

I'm still curious about your shader configurations and would be interested to hear some examples.

On the Pi I use Pixellate for all non-scanline situations and a tweaked version of CRT Caligari (stronger scanlines).

Fudoh, I read your post 3 times and I'm not 100% sure how to configure all that stuff, but I'll give it a shot if you can break it down for me. I'm new to shaders and shader configurations, a NOOB if you will!

no idea, sorry. But you could try how the shaders react to setting prescale factors within the emus.

[WelshMegalodon]

Skykid, any experience with using RetroArch via command line? I'm wondering whether it's less painful without that awful GUI, and the devs do claim it's a command-line program at heart at its core.

[Skykid]

Skykid, any experience with using RetroArch via command line? I'm wondering whether it's less painful without that awful GUI, and the devs do claim it's a command-line program at heart at its core.

Nope, only used the command line (or Terminal) for installing and setting up Floob's video manager, but that was before I opted for a CRT setup and is made for 720/1080 resolutions - so ended up being redundant for the time being.

I'm still curious about your shader configurations and would be interested to hear some examples.

On the Pi I use Pixellate for all non-scanline situations and a tweaked version of CRT Caligari (stronger scanlines).

Right and you use those in conjunction with each other (2 shader passes?)

[Fudoh]

Right and you use those in conjunction with each other (2 shader passes?)

no, it's either or. I replaced the two standard shaders Recalbox uses. The tweaked CRT caligari offers a very PVM/BVM like look, while Pixellate gets rid of the imperfect scrolling without any scanlines (but my Pi does output at 720p).

Have you gone through all the available shaders ? If you configure the controller right, you can change these on-the-fly during the running emulation. If you keep the integer scaling option on the emustation gui enabled (to get that vertical 2x scale) you might be able to find a shader that helps you with the hoizontal scrolling issues.

[Skykid]

Right and you use those in conjunction with each other (2 shader passes?)

no, it's either or. I replaced the two standard shaders Recalbox uses. The tweaked CRT caligari offers a very PVM/BVM like look, while Pixellate gets rid of the imperfect scrolling without any scanlines (but my Pi does output at 720p).

Have you gone through all the available shaders ? If you configure the controller right, you can change these on-the-fly during the running emulation. If you keep the integer scaling option on the emustation gui enabled (to get that vertical 2x scale) you might be able to find a shader that helps you with the hoizontal scrolling issues.

Right, but it sounds like Caligari and Pixellate have two useful functions, so I'm wondering why they're not used in conjunction (or does it mess up the image?)

I use the keyboard hotkeys to cycle shaders currently, but the default set aren't particularly geared toward 640x480 so a lot of them don't render too well.

I'm surprised you're using Recalbox over Retropie, I had a go with it and found it too limited.

[Fudoh]

I'm surprised you're using Recalbox over Retropie, I had a go with it and found it too limited.

cause for the hour (or so) every other week I find to actually play something I really appreciate the limited options of Recalbox.

Right, but it sounds like Caligari and Pixellate have two useful functions, so I'm wondering why they're not used in conjunction (or does it mess up the image?)

which are ? Caligari offers the same horizontal oversampling, just paired with a light raster effect, some blur and scanlines and since Pixellate doesn't work with your low resolution output, there's little else to choose from. I'm not sure what kind of output you're exactly looking for, but my best guess is that CRT Caligari plus a vertical integer scale should be fine.

If you run your games without any shader applied, but with integer scaling enabled, the vertical scrolling issues should't be there. I don't how MD or PCE emulation would be any different than SNES here. By default the horizontal scrolling is always buggy, unless you either chose a integer scaling here as well (which gives you a narrow image) or you apply a shader. Almost all shaders should fix the horizontal scrolling right away.

Why Recalbox and Retropie default to a setting without shaders and just offer integer scaling on the vertical is beyond me. I find the horizontal scrolling issues to be severe.

I would just try to find a shader that gets "most things" right and then go into tweaking the shader itself, e.g. minimize the blur on Caligari or adjust the scanline setting (if you want those).

[Skykid]

Hey Fudoh and others!

So I got back to my setup, downloaded a libretto shader pack and transferred crt-caligari.glslp to the following dir: /opt/retropie/configs/all/retroarch/shaders

Oddly enough, after restarting, it doesn't appear in the shader list with all the other shaders in the retroarch menu under the shader configuration. I went to the system configuration and found it there, and applied it as default for SNES. When going into SNES, the shader appears as applied in the retroarch menu - but there's zero visual change on screen.

I'm 95% sure that it's because it's not showing up in the default list (along with cry-pi and a host of others) that it's not displaying for me. The question is, which directory is it meant to go in, and am I supposed to have a corresponding cg file somewhere for this to work properly?

Appreciate the help!

[Skykid]

Anyone?

[Fudoh]

I have never configured shaders in Retropie (just in Recalbox).

You can check if the given files paths in the GLSP files match the location of the GLS files (which are the actual shaders) after you copied them to their intended destination.

[Skykid]

That already sheds some light on it! So there are two different files that need to be placed in two different paths?

I only found info on Google telling me where the file path is to place the shaders: /opt/retropie/configs/all/retroarch/shaders

Sure enough, all the other shaders are in there in glslp format, but when trying to access the newly inserted shader through the frontend in retroarch config (caligari), it's just not in the file list.

So what is a GLS file - something that instructs the system that a new shader is assigned/exists? I have no idea where they're located after 20 minutes rifling through FileZilla. I wish documentation for doing this was a little more clear.

EDIT: This is the entire content of the caligari.glslp file:

shaders = 1

shader0 = shaders/crt-caligari.glsl
filter_linear0 = false
scale_type_0 = source

Seems rather light on code...

[Fudoh]

I only found info on Google telling me where the file path is to place the shaders: /opt/retropie/configs/all/retroarch/shaders

that's where you place the GLSP files.

This is the entire content of the caligari.glslp file:

meaning you need another subfolder "shaders" and in it a GLSL file (which has the actual code).

Use these files here. It's not complicated. All files are there. Just make sure both files are present for all shaders and the paths are correctly set. https://www.sendspace.com/file/s4ll1p

[Skykid]

I only found info on Google telling me where the file path is to place the shaders: /opt/retropie/configs/all/retroarch/shaders

that's where you place the GLSP files.

This is the entire content of the caligari.glslp file:

meaning you need another subfolder "shaders" and in it a GLSL file (which has the actual code).

Use these files here. It's not complicated. All files are there. Just make sure both files are present for all shaders and the paths are correctly set. https://www.sendspace.com/file/s4ll1p

Ok many thanks big F! I'll grab those when I'm back on the PC and see if I can figure it out.

Only odd thing is this is the only file I got for caligari when I dl'd the libretro shader pack. Anyway, hopefully it will come clear when I see your files. Appreciate the help!