Fuse has a series on video filters available - scaling/simulating the video output on a TV, etc. Try one of those filters (TV x2 seem to simulate a CRT scanline display).
Not sure of Zesarux has more advanced options, you could give it a try.

Removing the curvature removes the morié pattern completely:

alt text

Which is a shame...I really love that curving for the old school feel, especially for the 2600 where there weren't any Trinitron sets yet!

@sad_muso you didn't say what emulator you're using. afaik even simple shaders are often very system bus intensive, so they're constantly fighting for bandwidth with the GPU, CPU, etc. afair, lr-genesis-plus-gx really hammers the system bus, so try using lr-picodrive instead, if you're using the former.

Are they CPU/RAM intensive or both? Does the Pi 4 cope with shaders better than the 3 B?

first part answered above. pi 4 will cope better.

Do overlays cause any hit on performance, specifically when used in conjunction with shaders?

yes, for whatever reason they seem to.

What is the least expensive way to implement curve and scanlines that is currently in existence?

the way you're doing it already - z_pi_crt.

The crt-mattias and crt-geom are way too demanding for a Raspberry Pi, they're not installed by default on the Pi - only on a PC installation.

@Sanctus Alas, I don't know Batocera or its directory tree at all. Maybe you should ask this at the Batocera forums with reference to this thread. I guess you are the Sanctus over there, too?

for everyone who is searching this "scanlines_by_default=yes/no" in the amiberry.cfg file without finding it (like me :D) -> it is now

line_mode=0 (0,1 or 2 possible; 0=none, 1=double, 2=scanlines)

So "line_mode=2" is the command in the config-file to have scanlines by default in the newer versions of amiberry.

@Nikorasu081 glad you got it working now!

Regarding the 117Hz display, I'm not sure. That number is actually computed from pixel_frequency timings so maybe is dependent on the current GPU clock. Are you using a good power supply?
Regarding the flickering, I have zero experience on using the composite out and CRT, so can't help you much there. Sorry! But yes, it does seem like having 117Hz instead of steady 120Hz can be the issue as you gradually get out of sync for the black frame insertion.

@xFlesk said in Amiberry. how to disable those awful scanlines ?:

i dont know what happend with this amazing emulator, but since some update it plays games with those disgusting scanlines which are completly gamebreaking for me. is there any way to turn this shitty scanlines off ? i cant see any option related to it in F12 menu.
thank you in advance

Assuming we're talking about the same visual affect, turning off Line Doubling in the Display section removed those scanlines for me.

I use HDMI to VGA at 640x480 too. Every emulator or even game can have its own resolution. I enabled the RunCommand launch menu and selected for each system (DMT-4 and 5 means 640x480). I don't know if I forgot something, but here it is.

RunCommand launch menu:
Select default video mode for "SYSTEMNAME" (DMT-4)
and
Select RetroArch render res for "SYSTEMNAME" (5)

Then you can disable the RunCommand. I also set the resolution of EmulationStation itself through the file

/boot/config.txt:
hdmi_group=2
hdmi_mode=4
config_hdmi_boost=5

No, Emulationstation doesn't have the ability to run shaders, that's something specific to RetroArch.

@dankcushions thank you for both the link and the configuration creation!!

Ok, so after I wanted play some games now, I realized the bottom part of the lr-snes9x games are always black. I can't say how many rows, but maybe 10th. The other sides are all on the edge of screen and Emulation Station is shawn correct, lr-nestopia too. Is there a setting I miss? The strange thing is, in RetroArch menu the whole screen is used. The emulator makes the image of game smaller and shows a black bottom border only.

EDIT: Ok so, after quick testing, it happens also in PC Engine, but not the other emulators.

I also have the pi2scart ouputting on a 28 inch consumer crt from philips and dont have those "problems". I cant even take photos of my scanlines becaues they are so subtile. Would like them a bit more beefy to be honest but its not that easy to get a pro crt here sadly.

@dankcushions Yes I think that is what it looks like. But it's much easier to see in motion.
It's not related to the resolution (I tried several).

I don't know if it's possible during the game, but it's such a great idea when the screensaver is displaying videos. I tried to set up once but failed, I only have now some blank images...

Please ignore this - I found out what the problem was, I'd turned on Shader #0 Filter to LINEAR. That is what was causing this effect in lr-genesis-plus-gx.

Many shaders include options to alter the effects they produce, including brightening the picture. Have you tried investigating that? Details for crt-pi on what you can change and the easiest way to make those changes.