I took some time to calculate and dial in the optimized settings for GBI (GBI-LL with 11:10 PAR and 1:1 PAR, and GBI-ULL). Google sheet here
I don’t have any GameBoy games, so this was all done for GameBoy Advance. In my opinion, for GBI-LL the results were best using the 1:1 pixel ratio. Using the default 11:10 resulted in some slight kind of ringing effect.
As a side effect, I now noticed that my Bandridge automatic switch does in fact cause some horizontal “smear” (I’ll post in one of the shmups threads about this). I had not noticed it at all before when using generic modes, and optimized mode for my SNES was blurry anyway since I have a 2-chip. Going straight into the OSSC gave perfect result, looks pretty awesome tbh, even when scaled to full screen. I’ll see if I can add some pics tomorrow.
The spreadsheet only lists 240p modes – wouldn’t it be better to set GBI to 480p output considering that GBA native resolution is 240×160? I added calculated parameters on wikipage but don’t have an actual Game Boy Player to test them with.
The low latency versions still output only 320 gameboy lines in 480p. GBI ull resizes the output to around 524×320 so it doesn’t look good with any samplerate including 866. ll version outputs 480×320 in 1:1 mode and looks good with 858 samplerate in 480p.
With the regular version you can set aspect to 3:2 and zoom 3x to make it fullscreen but if your display has overscan on 480p then parts of the screen will be cut off. It also has more latency and uses frame interpolation so scrolling is blurry sometimes.
The best for me is still GBI ll on 1:1 on 240p lineX5. Thanks Harrumph for the optimized settings.