RetroArch and 240p

I got my hands on an old CRT computer monitor (VGA, 31 kHz) this past weekend and wanted to play around with pushing out native-res, “240p” signals from RetroArch.

RetroArch doesn’t have any built-in resolution switching capabilities, but we can use the operating system’s built-in tools to handle the task. In Windows, that means using CRT_EmuDriver and a compatible GPU, while in Linux we can use xrandr from the desktop environment. You can also theoretically force resolutions via KMS, but I haven’t had any luck getting it going.

Since I’m running Ubuntu 14.04 (Trusty Tahr, LTS), I could add my custom resolution modelines to my xorg.conf and then choose between them before launching a game, but instead I am using launch scripts that add and set the desired mode at runtime. So, on my desktop, I have a little bash script that reads like this for SNES (EDIT: forgot a couple of things):

#!/bin/bash
xrandr –newmode “snes” 5.979 320 332 368 380 240 242 246 263 +CSync
xrandr –addmode DVI-0 snes // replace DVI-0 with your active display; you can find it from ‘xrandr -q’
xrandr –output DVI-0 –mode snes
wait 5 // this will ensure that RetroArch doesn’t launch before the screen fully switches resolution
retroarch –menu –fullscreen -c ~/.config/retroarch/snes.cfg \  // points to my pre-configured SNES controls 🙂
&& xrandr –output DVI-0 –mode 1024×768 // this will take us back to a normal resolution upon exiting RA

Notice that the last line only goes off once RetroArch closes, since it’s hooked to the launch command with ‘&&’.

RGUI automatically scales to the resolution and looks great. Oddly enough, I had to set my in-game aspect ratio to 16:15 to get everything to map up properly. Regardless, the results speak for themselves (these pictures are huge; click to check out the glorious full-res shots):

The only problem I have right now is that RA is detecting a refresh rate of ~47 Hz instead of ~60, for some reason, so it’s playing a bit slowly/jumpy. I can get a normal game speed by turning on the ‘threaded video’ option, but that’s suboptimal and leads to jerky scrolling. Regardless, this is a good start and I’ll be working with Squarepusher to iron out the current issues. If anyone has any experience forcing resolutions in KMS, please leave a comment or drop by IRC at Freenode – #retroarch.