Scanlines always uneven in certain resolutions

RetroArch Windows devices
#1

This is bugging me ever since i started using RA, some years ago.

It seems like in certain internal resolutions (like 640x480) scanlines are uneven. I must have tried every single preset and i can’t do proper scanlines with this resolution. Dreamcast, for instance is a problem. Same with many PS1 games that switch resolution to 640x480 sometimes in their menus.

Some other presets also seem to display scanlines vertically instead of horizontally. External resolution (my monitor res) don’t seem to have any effect on this.

Is there any way to make scanlines work at those resolutions? 640x480 internal resolution seems to be very often used.

#2

It’s core/platform/game dependent and most blackline shaders are designed for sub 240pm resolutions. Simply put, you can’t have even scanlines at non-integer resolutions. There is no way to fit 3 pixels in the space for two.

Older filters or whatever m other programs may have just been black lines at a certain opacity one pixel appart on the scales viewport. Shaders don’t work like that.

#3

Some of the CRT shaders have interlacing detection that will display alternating fields each frame when an emu switches to 480i resolution, just like a real TV would. CRT-geom does this, I know, and a few others, as well.

CRT-geom, crt-easymode and scanline.cg all look pretty decent at non-integer scales, but the scanline unevenness is still there if you look closely. Basically, as radius said, if you want your scanlines to look right, turn on integer scaling in your video settings.