The PS2 mostly outputs 480i/576i (there are exceptions, including every time you’re playing a PS1 game), but it’s better to think of that as a format (i.e., the NTSC and PAL formats, respectively) than a resolution. Different consoles all kind of operate at their own resolutions and (this part’s important), pixel shapes. Back in the days of SD standards, the TV itself did most of the heavy lifting at making these look consistent, but things don’t work that way now – that’s why the OSSC has sampling options.
People have done a lot of experiments and a lot of math to come up with the optimal timing chart, which based on the output of each of the systems listed – telling the OSSC how to interpret to signal to yield a consistent result onscreen. For the PS2, the standard optimal timings for the vast majority of games is:
H.samplerate=858, H.active=640, H.synclen=44, H.backporch=116
Now, this is for NTSC. If you’re PAL, things will have to be adjusted a bit (as Harrumph said above, you might have better results wit . On a regular TV, you could force the signal into a 4:3 aspect ratio and everything will be just about right. But we’re both using monitors, and they’re going to treat the signal differently, so getting right comes down how much time you’re willing to put into it.
My monitor processes the 4x signal in a way that won’t let me force it to 4:3, so I have to compensate by changing the samplerate, or everything looks too wide. Here’s what I ended up with:
H.samplerate=788, H.active=640, H.synclen=58, H.backporch=59
But my starting point was that first set of numbers. I spent more time than I’d care to admit with a test image I’d made open in Simple Media System and a ruler pressed against the screen. Measure, adjust. Measure, adjust. Use whatever you have at hand – some games (Silent Hill 2, for instance) have grids in their “screen calibration” settings that you can use. In a pinch, you can use the cubes in the “PS2 Configuration” screen, although I think that might actually be lower resolution than most PS2 games. In any case you’ll need to spend some time fiddling with the settings until the picture looks right – afterwards, I think you’ll get a better idea of what the different output settings on the OSSC should look like. But it will likely be unique to your system and your screen, you could end up with something entirely different than the standard settings or mine. (Especially since I’m NTSC, and I believe you’re PAL?)
I knew I got it right when I Was finally spending more time gaming than fiddling with the settings, but I’m having so much fun with the system now that I don’t regret a minute of it.