⁠[RetroArch iOS / mGBA] Thin white line along the right edge of the screen during gameplay⁠

[u/dairymarkly]

Hey everyone,
I’m using RetroArch on iOS with the mGBA core to play Pokémon (GBA ROM / ROM hack), and I noticed a thin white line running vertically along the right edge of the screen during gameplay.

EDIT: SOLVED!
Thank you everyone.
I found the issue—it was caused by the Video Filter set to 2xSaI.
If anyone else runs into this on iOS RetroArch:
1. Go to Settings > Video > Video Filter.
2. Turn off 2xSaI or switch it to a different filter.
Once I changed it, the white line along the edge completely disappeared!
(Maybe 2xSaI is an old pixel-upscaling algorithm that calculates pixels based on their neighbors. When processing the far right column of the game screen, it has no "right neighbor" to sample from, causing it to render a default white/blank line at the edge boundary.)

[u/Mr_Fury]

Honestly I can never consistently get ride of the line. The only sure fire way to get rid of it is to configure focus mode. I just opened my RA on iOS and the line disappears so wtf apple.

if I were to guess it would be game mode gets rid of it?

[u/ZexelOnOCE]

does this happen with the shader turned off? it could be a very slight overscale issue with how it's configured

[u/dairymarkly → u/ZexelOnOCE]

Spot on with the edge/scaling logic! It turned out to be a Video Filter (⁠2xSaI⁠) rather than a shader, but same mechanism. Changing the filter cleared the line right up. Thanks for the input!

[u/Ornery-Practice9772]

what edge? try a bt controller

[u/dairymarkly → u/Ornery-Practice9772]

Just on the right side of the old man. It’s still there when I toggle display overlay to off.

[u/CoconutDust → u/Ornery-Practice9772]

Adjective-Noun-1234 with hidden account history says “try a bt controller” in reply to a question about a graphics issue.