Jo Engine: JO_480p Makefile Option

[rorirub]

Anyone have a SCART input built directly into their TV? The last test I would like to perform is trying to obtain a 480P signal via a SCART cable plugged directly into a TV. I assume this is safe but I have no idea. Any volunteers?

I tried that before and it simply won't sync as the TV only expects 480i signal in the SCART input. However, this may be different from TV to TV.
If I wire up VGA output on the Saturn using the hsync and vsync pins from the vdp2, then it will work in anything with a VGA input (tv, lcd monitor, crt monitor), but of course 480i will not display on those (it would need one of those multisync monitors that accepts 15KHz input to work with both).

However with SCART -> OSSC -> HDMI, all the modes work. As long as you use a decent cable. If you use a cable with a sync splitter built in, the progressive modes may not work, the sync signals produced by the splitter will be bogus. But with the official European cable it works (even with NTSC machines since the OSSC doesn't look at the rgb selection pin).

 

[slinga]

@Jameson ,

Any luck?

 

[hitomi2500]

Oh, i forgot about this test, sorry. The cable arrived, i tried outputting hires with my own code, and 480i worked with 448 lines but failed with 480 and 512 lines (there was some image, but completely out-of-sync). Haven't tried 480p yet, will try today.

 

[slinga]

You can try my 480p ISO: Release 480P Mode Demo 1.0.0 · slinga-homebrew/480P-Mode-Demo if it will save you some time. It has a bunch of resolutions, the last 4 are 480p resolutions.

 

[hitomi2500]

You should probably take my results with a grain of salt, because my TV is digital, and it does some magic digital auto-syncing that most scart-equipped TVs from the Saturn era probably didn't. I didn't wrote the list, but all in all, most interlaced modes work normally (with some border shifts sometimes, but that might be due to sync magic), except for some 512 (and probably 256) lines modes, they lose sync but the picture is mostly there.

As for progressive, it's... strange. It doesn't work normally, but the picture is partially visible and the image is stable. Here are the shots.

 

[hitomi2500]

Tested it a bit more. FWIW, when switching slowly (~30 seconds per mode), every interlaced mode works. But if i switch fast, some modes might lose sync, mostly 352/704 x 224/448, but 704x512 failed once too.

All x240/x480 modes have screen cut from the top and bottom, x256/x512 from the bottom only, and every 352x/704x from the left.

Out of progressive modes, only 352x480 is semi-unstable, losing sync a bit, but the fonts are barely readable in 640x480 and 704x480.

 

[rorirub]

Yeah, that's the resolution test I tried before, I found it here 10+ years ago. Sometimes when you switch it will randomly corrupt the screen. It's a bug in the demo, not the display. The display still syncs fine - you'd get a rolling image or random blanking if the image wouldn't sync.

In the progressive modes, if you use it with OSSC, it depends on the cable whether you lose sync or not. The official PAL cables work. Cables with built in sync splitters will not work (the OSSC does its own sync splitting, so they are not needed). I have not tried cables that use native c-sync from NTSC consoles or ones that use luma on sync; logic would dictate that luma on sync would work, but for the native c-sync, it depends on how OSSC handles the signal.

And the x256/x512 modes only work on PAL consoles, on NTSC ones they simply do not display the bottom. It's not even hidden by overscan, the VDP2 simply displays 240/480 lines max and omits anything extra.

 

[stevekwok]

Implemented 480P modes