Pi2SCART: scanlines too thick!

matchaman

Just got my Pi2SCART today. All seems great, messed up with timings, everything looked great... then I realised that the scanlines are way too thick on my 29" CRT TV (trinitron tube).

The lines are so thick that I can see them from "sofa distance" and they started making my eyesight fuzzy because they're completely "dark"!

I tried using slightly higher resolutions than 240 lines but it didn't correspond to any native resolutions of systems and the lines remained thick.

Till now I used 240p via composite and the scanlines were perfect; just enough thick to give the desired effect. I guess it has to do with composite's limited capacity...

Note that I tried a 14" CRT and Pi2SCART looked perfect, the scanlines seemed much less evident. Is it totally up to theTV and there's nothing I can tweak on my system? :/

caver01

@matchaman why are you trying to get scanlines on a CRT? Isn't the point of scanlines to reproduce the look of an actual tube? And you are already using a CRT? I don't get it. Your set should already have scanlines, RGB triads, or whatever glass tube/phosphorus effects it has. You should be golden without adding anything!

dankcushions

@matchaman said in Pi2SCART: scanlines too thick!:

I tried using slightly higher resolutions than 240 lines but it didn't correspond to any native resolutions of systems and the lines remained thick.

can you explain how you used higher resolutions? by what process? because only 240p will produce scanlines on a CRT, but maybe you weren't actually changing anything that would really change the resolution.

matchaman

@caver01 I am using Pi2SCART to get RGB 240p signal. The scanlines I'm referring to are the natural scanlines of the CRT TV but they're far more (too much) evident via RGB while composite gives a more balanced overal image despite its lower quality.

@dankcushions I could get up to 260 non-interlaced lines via hdmi_timings if I remember correctly, in an attempt to see if the scanlines would become less evident.

I later tried a real Mega Drive with RGB and it also gives thick and dark scanlines. The picture is identical to the Pi2SCART output at 224 lines(which is good news) but still, it feels almost artificial.

dankcushions

@matchaman ah, right! yes, it kinda makes sense that composite is less vivid. thinking aloud: the scanlines are the absence of a signal when you send a CRT a progressive scan signal of less vertical resolution than it can display, so it shows:

row of pixels
nothing
row of pixels
nothing
row of pixels
(etc)

the nothings appear as blank (black) lines. it would make sense that scart has more vivid black lines as it is a sharper signal, whereas composite would be less so, blurring the effect slightly.

i guess composite is probably the most 'authentic' since i don't remember any of the pre-32-bit consoles having official RGB scart cables. i think the first one i remember having RGB scart was the PS1.

man, i want a CRT...

matchaman

Excellent diagram, I would have never explained it better! :)

It's literally one black line for every row of pixels, the thickness is exactly the same, which I would never expect. It's an overdose of a desired effect that gives a negative overall result. Even my wife said "why does it look like it's behind vertical bars? it makes me dizzy!"

I came to the conclusion that it's definitely not something that could be tweaked by code or different hardware (such as the RetroTINK). The large size of my TV (29") and the accuracy of the Trinitron tube shows exactly what it should and 240 lines are way too small of a resolution for it.

Maybe my case could help others consider using a smaller CRT TV or one with less accurate specs, since Trinitrons are very "punctual" in terms of showing precisely the signal they're given without softening things out.

As for the 8 & 16-bit consoles, indeed all we had back then was RF and composite. Actually some NES games took advantage of the composite signal for added effect, such as Link's face looking more cartoony due to the artifacts around his sprite in Zelda II!

ghogan42

@matchaman said in Pi2SCART: scanlines too thick!:

Excellent diagram, I would have never explained it better! :)
It's literally one black line for every row of pixels, the thickness is exactly the same, which I would never expect. It's an overdose of a desired effect that gives a negative overall result. Even my wife said "why does it look like it's behind vertical bars? it makes me dizzy!"
I came to the conclusion that it's definitely not something that could be tweaked by code or different hardware (such as the RetroTINK). The large size of my TV (29") and the accuracy of the Trinitron tube shows exactly what it should and 240 lines are way too small of a resolution for it.
Maybe my case could help others consider using a smaller CRT TV or one with less accurate specs, since Trinitrons are very "punctual" in terms of showing precisely the signal they're given without softening things out.
As for the 8 & 16-bit consoles, indeed all we had back then was RF and composite. Actually some NES games took advantage of the composite signal for added effect, such as Link's face looking more cartoony due to the artifacts around his sprite in Zelda II!

Well the actual scanline effect shouldn't depend on the rgb/composite connection per se. Composite is softer for sure and has all of the color artifacts, but those are on the horizontal axis, not the vertical. If the system is outputting 240p then it's the TV that's spacing those lines out and leaving the blank space in between.

If the black lines are less prominent with composite it's probably because the composite signal is brighter (higher voltage) and the beam is spreading out. You can try turning up the contrast on your tv with the rgb signal and see if the scanlines blend together more. They should!

But I know what you mean. When I went shopping for my Sony PVM I purposely bought an older less capable model because I didn't like the ultra-sharp scanline effect that the high end models had. So I bought a cheaper, older 14 in model. And later I bought 17in JVC security monitor that looked more like what I think of as a real tv (but still had s-video). Also I think larger TVs do exaggerate the scanline effect.

So you might need a small crappy TV to be happy! I know I like my c64 monitor for my NES.

dankcushions

@ghogan42 yes, that makes perfect sense! a sort of 'bloom' effect from brighter pixels.

matchaman

I messed a lot with contrast, brightness, etc but the black lines always remained as thick as the filled ones, it's always extremely defined and clear. And I absolutely agree, the composite signal seems to give a much stronger brightness and an overall powerful feeling with that old school "blooming" thinning out the scanlines.

For example, whites on RGB look "true paper white" while on composite they appear much punchier and light emitting with the same TV settings. It's actually hard to explain in words and since my camera gives terrible results, it's impossible to capture anything but you get the idea.

I also agree with smaller "crappy" TVs because I conclude that the best way to play retro games is to use the equipment that was widely used back in the day: a mediocre CRT TV between 21-25" which was the mainstream till the late 90s. Another option is PVMs of course but I couldn't locate one without noticeable burn-ins or dying brightness.

Smaller low/mid-end CRT it is then with the added bonus of curvature! :)

Yuke

I also have the pi2scart ouputting on a 28 inch consumer crt from philips and dont have those "problems". I cant even take photos of my scanlines becaues they are so subtile. Would like them a bit more beefy to be honest but its not that easy to get a pro crt here sadly.