PC to regular TV (not PVM) over S-Video with 240p?

[xewgramodius]

I'm trying to output 240p from my PC to a regular TV via S-Video or Composite, and still get true 240p res.

I've googled on this quite a bit and posted in other forums, but none of the solutions work.  I think this is because most are doing one of the following...

A)  Connecting a real arcade PCB to a regular TV using a Jrok RGB-to-NTSC convertor, or...
B)  Connecting a PC+GroovyMAME+ATI+CRT_emu to a PVM using a VGA-to-5BNC cable, or...ion i
C)  Connecting a PC+GroovyMAME+ATI+CRT_emu to a regular TV via VGA-to-SCART cable-->SCART-to-ComponentConvertor-->Component input on TV

...but my TV doesn't have a Component input

I bought the Jrok convertor, which has Component, SVideo, and Composite out.  However, I cannot get a proper picture.  I had to build a cable, as the Jrok takes 5 pins (R,G,B, Sync, & Ground) but I can't get it right.  I have the H and V pins combined, and all the grounds combined, but the picture is a red, scrambly mess.  I can, however, get a perfect 240p picture into my PVM (again, using GroovyMAME and CRT_EmuDriver).

I guess my main question is whether the Jrok can even do this (as I know it's intended for arcade boards)?  Will CRT_EmuDriver not generate the signal that the Jrok wants?

[buttersoft]

Arcade boards normally generate 2Vp-p+ video signals, where a PC GPU outputs the RGB lines at 0.7Vp-p, so it might be that, though i can't say for sure. It's not that crt_emudriver is doing this, that's just how PC RGB levels come. You could try a J-pac, which is expensive, or just a THS7314 or THS7316 if you want.

The scrambly part probably means your problem is sync-related though. The newest versions of crt_emudriver can output composite sync on most (all?) GPU's. It's an option you enable in VMM, and it then comes out of VGA pin13/H-sync, so you only need four cables not five. Have you tried feeding that into the j-rok, as that's what an arcade board would output - again, probably at different levels. I'd go for this option first. You can also try adding resistors or potentiometers in the sync lines. Pots work best as you can dial them around easily.

A PVM will normally be happy to take the PC's sync output even if you just combine the H- and V-syncs which have a DC offset of +5V, so no surprises there. (This isn't always the best idea though, and as the PVM gets older or crankier you might want to add resistors there too - just saying )

You should also get in contact with whoever makes the J-Rok stuff, and see what they say. If they sold you something they'll surely try to help you.

[xewgramodius]

Holy ballz that worked!

I enabled Composite Sync in VMM, then cut VGA pin 14 leaving 13, and ran it through the Jrok.  The picture was really dark at first but there are pots on the Jrok itself for fixing that.
What a journey (to 15KHz heaven).  I feel like I'm just at the tip of the iceberg now, though.

Thank you *very much* for your expert help (c:

Hmm, I wonder what made the Jrok angry with the H+V sync?  I tried combining the lines both with (1K) and without resistors.

[buttersoft]

Holy ballz that worked!

I enabled Composite Sync in VMM, then cut VGA pin 14 leaving 13, and ran it through the Jrok.  The picture was really dark at first but there are pots on the Jrok itself for fixing that.
What a journey (to 15KHz heaven).  I feel like I'm just at the tip of the iceberg now, though.

Thank you *very much* for your expert help (c:

Hmm, I wonder what made the Jrok angry with the H+V sync?  I tried combining the lines both with (1K) and without resistors.

Most devices that want Composite Sync are not happy with you just mixing the H- and V-sync outputs from your PC. PVM's are normally ok with it for testing, but they're one of the exceptions.

I'm actually after some info on those J-rok thingumies. Are you getting real 240p out of it, no flicker or anything? Are there some specs saying that that's what it does?

[xewgramodius]

I'm a scanline junkie so I'm 99% sure I'm getting true 240p through this, but I had to run right after I got it working, so I'll take some pics tonight and post them.

[buttersoft]

More importantly, are you getting a 1:1 conversion. So what goes in as RGB, comes out as S-Video Y/C - whether that's 240@60p, 288@50p and everything in between. You could measure the sync output with a multimeter set to frequency, if you have one...?

[xewgramodius]

Here you go...
https://imgur.com/a/AOBg5

As for what res it's running at during games, well, I'm using the superResolutions config for CRT_EmuDriver (2560x240 in the case of Double Dragon) but, no, I haven't verified that it actually switched to that exact res.  I should run some games that have oddball resolutions.  I can get 480i, that's for sure.

I do have a multimeter, but I'm kind of an EE n00b.  I do know a guy who can help me run such tests, though.

Next task is to see if I can adjust the front porch.

[buttersoft]

Next task is to see if I can adjust the front porch.

Yep, open ArcadeOSD, go to the resolution you want to edit, then into horizontal geometry. You adjust the number of lines in there, with ESC to go back if something goes wrong. You can save the resolution for use in other emulators, but go into the edit modeline option and write down the three horizontal timings in ms. You then go into mame.ini and change your monitor to custom (it should be already) and update the crt_range0 line with your improved timings. See line from the generic_15 preset below, with relevant timings highlighted. Note that this only works for horizontal geometry to correct overscan, and doesn't work for vertical geometry at all.

crt_range0  15625-15750, 49.50-65.00, 2.000, 4.700, 8.000, 0.064, 0.192, 1.024, 0, 0, 192, 288, 448, 576

You can also create a new custom present in your monitor.ini file, and redo your modelines with VMM. It's worth doing this if you're only a week or two into setting up, as i can guarantee you'll want to do the modelines over a few times

That image looks ok, actually. One way to tell would be to get a grid picture, fullscreen it in windows photo viewer when the desktop is at 240p and then again at 480i and see if there's a difference in screen flicker and resolution. A 240p grid from the PC will be slightly less detailed, but will flicker a lot less if the J-rok is outputting 240p.

Next might be the issue of it outputting in discrete bands, but mb the supplier could clear that up.

[xewgramodius]

Yeah, I put up some video test pattern images full screen and it's definitely higher-detail, but flickery, at 640x480.  And lower-detail but no flicker, with scanline gaps, in 320x240.  Pretty confident about it.

I also switched to resolutions like 512x512, 384x240, and 256x224 and they came up fine and looked as one would expect.  Every res that was less than 512 horiz had no flicker.

Man, looking at computer desktops with interlacing takes me back to my Amiga500 days, using DeluxePaint IV in HAM mode...

[xewgramodius]

Yep, open ArcadeOSD, go to the resolution you want to edit, then into horizontal geometry. You adjust the number of lines in there, with ESC to go back if something goes wrong. You can save the resolution for use in other emulators, but go into the edit modeline option and write down the three horizontal timings in ms. You then go into mame.ini and change your monitor to custom (it should be already) and update the crt_range0 line with your improved timings. See line from the generic_15 preset below, with relevant timings highlighted. Note that this only works for horizontal geometry to correct overscan, and doesn't work for vertical geometry at all.

OH, that's what AracdeOSD is for.  Thanks again for that tip.  I actually thought I had no control over the geometry in this regards, so this is a pleasant surprise.  THANK YOU