I have made a couple of builds that add PWM on the 18-bit DAC to get 24-bit color for the cores that need it. This is for any signal that uses the VGA port on the IO board. It works by quickly alternating between two different color values to get a color in between. The PWM happens very fast so it can be done even for 640 wide images.
We have been testing it on the Mister FPGA discord, here are some pictures:
Active Y/C S-video PWM off:
Active Y/C S-video PWM on:
I have included a build for N64 and PSX, PWM is always on in these builds, no settings needed.
Here is my fork of the n64 core with the PWM changes: https://github.com/Jokippo/Mister64PWM
It seems to work quite well and may be a good alternative to using direct video or buying a new 24-bit IO board. Hopefully these changes can be added to the Mister framework at some point, but I am still doing some testing for now.
edit: Updated N64 core to most recent source. PSX core had some red color shift on component, might be a bit less on this build.
edit2 13/02/2024: Update to latest N64 changes and disabled PWM for scaled output as it was causing jitter.
edit3 15/02/2024: Added Groovy core with PWM.