@dankcushions so you'd need to set up a config for every arcade that has a overscan output? There's an awful lot of them - eek!
unfortunately it’s probably necessary. it’s possible to automate some of this stuff - i believe i experimented with letting them overrun by a certain tolerance when developing https://retropie.org.uk/forum/topic/4046/crt-pi-shader-users-reduce-scaling-artifacts-with-these-configs-in-lr-mame2003-lr-fbalpha-lr-nestopia-and-more-to-come
the issue is that arcade machines, unlike console games, had CRTs that were manually configured for the game. so they often have crucial gameplay info (eg score) running right to the edge of the image, because they knew an engineer/arcade operator would be adjusting the CRT to suit.
for this reason it’s probably not safe to automate an amount of ‘overscan’ in arcade games.
You allude to being able to figure out the custom resolution but how would you do that from config files?
you have to manually do it whilst the game is running
Also how do you see your change where it outputs the resolution on screen?
when you adjust the resolution in the menu it should be visible behind, no? the menu is translucent.