MiSTer FPGA Forum

Hey guys,

I currently run Minimig at 800x600 to handle the interlaced resolutions with vga_scaler/force_scandoubler both enabled, if I leave vga_scaler off, then it won't handle the interlaced modes at all (This is a known limitation as far as I can see, as it can't be scan doubled), all I get is loss of sync blank screen. So I'm after resolution suggestions modelines/video_modes that you guys use that work well on your CRT.

Thanks!

Not sure, but I would really like to see it double interlaced resolutions from 15KHz to 31KHz if that's at all technically possible, repeat every scan line twice I guess.

Doesn't it already do that with force_scandoubler? I don't have a CRT, so I'm pretty ignorant about the Mister facilities, but I thought scan-doubling 15KHz was one of the basic features of the core?

Malor wrote: ↑Thu Dec 22, 2022 10:56 pm

Doesn't it already do that with force_scandoubler? I don't have a CRT, so I'm pretty ignorant about the Mister facilities, but I thought scan-doubling 15KHz was one of the basic features of the core?

I don't believe it doubles interlaced in the manner I was thinking, that's what I was told before when I asked. I think it deinterlaces in the traditional sense (like a flicker fixer) rather than simply making a perfect copy of the interlaced signal that will run on a 31KHz display. I'd rather not have it deinterlaced ideally given the artifacts that causes. But maybe I'm misunderstanding the whole thing.

force_scandoubler doesn't do any de-interlacing and will not produce a progressive signal. Instead its going to be 960i which I'm not sure any display can understand. Its main purpose is to take 15khz 240p and up it to 31khz 480p, both progressive formats.

Currently system-wide de-interlacing has to be handled by the scaler, defaulting to weave mode. A handful of arcade cores can be toggled to generate real progressive output and there's a similar hack in the PSX core, but this has to be done internally by the core's own logic.

What I'd like ideally is taking 15KHz 540i PAL (or would it be 625i?) and make it 31KHz 625i, but I am not sure that is technically feasible.