Why Doesn’t the Scan Doubler Work With PSX Core?

[geiger9]

Is this is one of those things where it just can't possibly work or is it one of those things where someone might get it to work in the future?

What is the reason why it doesn't work?

[DevilHunterWolf]

Scandoubler is an outdated and basic system back before the current filters system was implemented which are found under the Video Processing menu. There's no reason to use Scandoubler as any of the effects it can create can be replicated with more control and options with the filters system.

If I had to take a guess as to why it doesn't work with the core is that PSX deals with resolution changes in many of the games which Scandoubler probably doesn't play nicely with. Even the BIOS changes resolutions between the Sony logo and the PSX logo. I couldn't tell you exactly how it works but I've seen the resolution and scale change with Scandoubler in pixel perfect and low latency modes exaggerating the effect. If I'm correct at all, both the core and the Scandoubler trying to do their respective changes would cause problems. That's my guess as to why it doesn't work.

[FoxbatStargazer]

Scandoubler is an outdated and basic system back before the current filters system was implemented which are found under the Video Processing menu. There's no reason to use Scandoubler as any of the effects it can create can be replicated with more control and options with the filters system.

The scandoubler is still ideal for 31khz analog output to compatible CRTs for perfectly matching resolution without having to mess with scaling, blank screens or input lag. It seems to have been created for multi-scan PVMs and works well with VGA monitors also.

I believe fpgaspazumpass said something to the effect that the horizontal refresh clock in PSX isn't static, thus merely doubling it won't work like in the other cores. So it sounds basically impossible. If you are using something like a VGA CRT, you will need to use vga_scaler and dial in an appropriate video_mode. (and yeah, filters if you want scanlines etc.)

[thorr]

My assumption is because it can't work with 480i. The scan doubler draws each line twice as it goes down the screen. Interlaced modes need to be every other single line.

[FoxbatStargazer]

I guess I forgot that there's a force 480p render in the core's options now. That might work direct analog out to a 31khz display? But there are also compatibility issues with some games. Also no scanlines that way.