How to get the crt-pi shader looking good on 480p games?

[Darksavior]

I'm using the fkms_rpi4 branch with lr-flycast but this problem has always existed when I'd upscale to 480p with lr-pcsx-rearmed. My output is 1080p.

Offtopic, but I get similar visual issues on a playstation classic (which can only output 720p) when using the same shader on nes, snes, etc.

[Darksavior]

Can we bump posts? ;p

[dankcushions]

@Darksavior 480p on a CRT wouldn’t have scanlines, but it looks like the case of SFA3, which is a 240 pixels high game, it just runs at 2x upscale on a dreamcast. in that case, i think the only way to do it would be to change the ‘scale’ in the shader options menu, if i remember the screen correctly.

for most other DC games you wouldn’t want to do this, since they would normally run at native resolution (480p?) so wouldn’t need the scale to be adjusted, although they probably would look strange with scanlines anyway.

[Darksavior]

@dankcushions Well, this happens with any system that's above the native res of 240p (or similar). Which is dreamcast and some ps1 games. I still use 1080p output res for the shader. Well, dreamcast did have a composite output so it did have scanlines when using a crt tv. Unless it would downsample to 240p when doing that, but that's overthinking things..
I tried to adjust the scaling through the rgui but it wouldn't do much and just slow things down. Oh, well..

[dankcushions]

@Darksavior said in How to get the crt-pi shader looking good on 480p games?:

@dankcushions Well, this happens with any system that's above the native res of 240p (or similar). Which is dreamcast and some ps1 games. I still use 1080p output res for the shader. Well, dreamcast did have a composite output so it did have scanlines when using a crt tv. Unless it would downsample to 240p when doing that, but that's overthinking things..

nah, only 240p resolutions have scanlines via composite. https://www.google.co.uk/amp/s/amp.reddit.com/r/crtgaming/comments/4z3rq8/do_only_240p_games_have_scanlines/.

[Darksavior]

@dankcushions But scanlines make everything look good! Ah, Oh well. Thanks.

[dankcushions]

you can definitely get scanlines at higher than 240p resolutions, just the example you've got is a game that is 240 pixels high natively, but for whatever reason the game/core is reporting it as 480 pixels high (that's either correct or incorrect emulation, but either way), so the you're getting scanlines appearing in the middle of a single row of pixels (as well as between).

note also that scanlines typically need a display resolution of 4x the height native resolution to look good (ie, you have 4 rows of pixels for every scanline). 240x4=960 so more or less anything over than that will make the scanlines look hazy/ugly and have scaling artefacts unless you're running at 4k, etc. i haven't tried the pi4 at 4k60 but i would guess it would struggle, especially with shaders.

[Darksavior]

@dankcushions Something to look forward to test in the future whenever the optimized mesa drivers get released. The mesa drivers included with redream (dreamcast emulator), makes every game run at ~60fps with minor drops. On stock speeds. Compared to flycast which struggles ~30-40fps sometimes like crazy taxi.

[ANDRELLVS]

Leave SHADERs and use OVERLAYs which simulates scanlines.

1 - install overlays from the retropie menu
2 - go to the folder:
/opt/retropie/emulators/retroarch/overlays/effects/scanlines/
take an overlay file and copy it to your computer, as well as your configuration file
3 - The overlay file is a png that can be cut into photoshop or other simpler programs. cut to fill exactly 640x480 in length.
4 - so remember in the configuration file and png file names etc where you have some resolution (example 1280x1024) you replace with 640x480

note that you are creating your 640x480 overlay from scratch

5 - enable overlays and select the one you created that has 640x480.

this is the method i found to make scanlines correctly match the pixels displayed on the screen

OBS: My english is bad, i am using google translator, i hope nothing written has got double meaning here too. Because in my post about EMULATIONSTATION LOCATION one person even complained.