Dell Ultrascan p991 (and scanlines on vga monitors)

[karmeck]

In this current market I do not have the money for a pvm/bvm, or the patiens to wait for one.

So I bought a crt monitor instead. Images is beautiful.

Im currently trying to get this to work:
https://www.youtube.com/watch?v=Y9E3KB0bmLY

Witch is 240p at 120hz to generate scanlines (but keep the brightens)
Cant get it to work. Though I'm using a hdmi to vga converter.

SO currently I'm using filters.

Spoiler

I think this is were I get of from the hunt for now...... maybe find a bigger crt monitor now.......



Edit:
Found the service manual:
http://www.go-gddq.com/upload/2009-11/0 ... IS8y6_JsKX

[Xer Xian]

Please don't use filters on CRTs! It's like seeing a naturally beautiful lady that's had heavy plastic surgery

[BazookaBen]

Yeah, I'd recommend just running 1920x1440 (240x6=1440) and adding scanlines, but no filter. Adding a CRT filter to a CRT seems like it would end up not looking that great. Especially considering most of these filters are designed specifically for LCD pixel structure.

[karmeck]

im using filter untill I can get this to work: http://www.retrotink.com/

this part:

The 240p 120Hz mode is suitable for VGA monitors. Running at a vertical refresh of 120Hz allows the monitor to display 240p while maintaining a 31.5kHz horizontal sync. This is great to get real scanlines without using a shader which throws away half the screen brightness. A side benefit of 120Hz is that you get lower lag. To reduce motion judder, go into the video settings and set set Vertical Sync Swap Interval to 2 from the default setting of 1. Also if you're using a VGA monitor, don't forget to slide the sync switch from CSYNC to HV.

might have to buy his converter.

When you say add scanlines, do you mean by using a scanlines generator?

and there is something strange, 4:3 looks like 4:3 on a widescreen (black bars). only buy going 16:9 in retroarch dose the snes game fill the screen. frontend looks find though.

[BazookaBen]

im using filter untill I can get this to work

Oh that thing looks pretty cool. 240p on a P991 is going to be pretty dark though, because even 480p and 600p have scanlines. They get bigger as you drop in resolution, so at 240p your screen will probably be mostly black.

Also, 120hz to play 60fps games will give you a slight "ghosting" image. Set your P991 to 120hz on your PC and check this page out: https://testufo.com/. The bottom UFO will be what your 240p games will look like. Not terrible, but 480p60hz without scanlines might be the better option. The best option is actually 720p or 960p on an OSSC, because 480p is such a low resolution for the P991 that it displays scanlines, which is not good for 240p content (you will have two scanlines for every one colored line in your 240p signal)

and there is something strange, 4:3 looks like 4:3 on a widescreen (black bars). only buy going 16:9 in retroarch dose the snes game fill the screen. frontend looks find though.

That's because SNES games don't have square pixels, and when you translate that to a resolution with square pixels, it squishes the image. The optimal thing to do here is to create a custom resolution with CRU

When you say add scanlines, do you mean by using a scanlines generator?

The scanlines with an emulator would be via a filter in the emulator that does only scanlines. But most CRT filters add more than just scanlines, they also simulate the shadow mask/aperture grille. The problem with that is: your P991 already has an aperture grille. So you're displaying a fake aperture grille over a real aperture grille

[karmeck]

snip

Sorry, I never stated that I'm using a raspberry pi 3b. So Cru is not an option.

And in the YouTube video I think it looks fine, but in the comments one user links to an other way to do it that also looks good.

User is fonarte
https://abload.de/img/img_20170603_0205064dyc2.jpg

[Xer Xian]

In my experience, having a CRT display 240p or 480p with scanlines at ~80% intensity yields essentially the same result. ** I can post camera shots showing that.

Moreover, by running your CRT at 120Hz with your content only being 60fps you either end up with jerky motion due to uneven cadence (like Mike Chi experienced in the video you linked) or increased motion blur due to higher persistency (every frame will be displayed twice, but the phosphors decay is a fixed 1 or 2ms, meaning that every row will stay on-screen for double the time). Or both actually.

(this is assuming that emulation is capped at the original fps, which should be the case)

** More precisely, a CRT with 0.25mm AG pitch

[karmeck]

I'm leaning more and more towards running it at 640x480 with a scanline overlay, I found one here: https://blog.petrockblock.com/forums/to ... ut-border/



if you know of any better pleas tell.

Edit: this one seem good as well.

https://retropie.org.uk/forum/topic/315 ... on-a-crt/8

[BazookaBen]

I'm leaning more and more towards running it at 640x480 with a scanline overlay, I found one here: https://blog.petrockblock.com/forums/to ... ut-border/



if you know of any better pleas tell.

You have a p991. It can display up to 2304x1728 at 60hz. So no need to limit yourself to 480p

Like I said, 480p is such a low resolution for the p991 that it already has scanlines. So if you use a scanline overlay, you're adding scanlines to scanlines. I'd say you need to run at least 960x720 or 1280x960, then add scanlines. It will look way better.

Do you have an analog output on your retro-pi? Or are you running HDMI to a DAC? If so, what DAC?

[karmeck]

Here is what I'm using right now https://s14.postimg.org/3qtj518u9/IMG_2 ... 200530.jpg

Hdmi->vga
that I got when I bought the monitor.

I'm thinking of getting the RetroTINK-ULTIMATE with vga output.

Thank you for all this info. I'm learning. Previous I used solutions were everything is just plug and play.

[BazookaBen]

Something to keep in mind, different DAC's have different maximum pixel clocks. Most (and probably yours) top out at 1080p60, which is still more than enough to run 960x720 and 1280x960. But something like 1920x1440 would be out of the question.

This is a thread you should follow, we've been talking about them recently here:

https://hardforum.com/threads/24-widesc ... ts.952788/

I'm also curious about the max pixel clock on that analog-capable retro pi

[karmeck]

Found a 1280x960 overlay.

http://i.imgur.com/rcaf5Tj.png

Will try Monday.

[karmeck]

Found a 1280x960 overlay.

http://i.imgur.com/rcaf5Tj.png

Will try Monday.

And here we are

Spoiler

Spoiler

That is using the 1280x960 overlay I linked to above.

[BazookaBen]

That is using the 1280x960 overlay I linked to above.

So you're not noticing anything off about that?

Many old school games run at 224p, not 240p, and it looks like you're not using an interger scale with 224p games. Look at Mario's buttons on his overalls (3 lines instead of 2), and the whites of test-suite guy's eyes (2 lines instead of 1). Scanlines are no landing in the proper spot.

So for 224p games, you probably need to create some 896p resolutions, and either find an 896p overlay, or crop the 960p one.

EDIT: I'll try to get some pics on my SD CRT to show you what theyr'e supposed to look like.

[karmeck]

That is using the 1280x960 overlay I linked to above.

So you're not noticing anything off about that?

Many old school games run at 224p, not 240p, and it looks like you're not using an interger scale with 224p games. Look at Mario's buttons on his overalls (3 lines instead of 2), and the whites of test-suite guy's eyes (2 lines instead of 1). Scanlines are no landing in the proper spot.

So for 224p games, you probably need to create some 896p resolutions, and either find an 896p overlay, or crop the 960p one.

EDIT: I'll try to get some pics on my SD CRT to show you what theyr'e supposed to look like.

I just found the option to integer scale. Will try it when I get home.

I will try using this overlay that, if I have understood this correctly, adapts to the image.
https://forums.libretro.com/t/scanline- ... ct/2425/11

I found the converter I'm using and it is indeed capt at 1080p@60hz.

[Xyga]

In vanilla MAME you can just use small overlays of just the required pixel height (and whatever width you desire) matching the integer factor of the game system source.
You can then assign a specific png to each system using .ini files. Per driver is the fastest way, only need to make a handful.

Dunno if it's doable with your thing though, RetroArch and alike remove a number of useful controls from MAME.

EDIT: you'll never find a single overlay that adapts to all game hardwares as Ben underlined, you'll need to have a number of those but if RA doesn't let you assign overlays per hardware like vanilla MAME using ini files, mayve there's another way? (per game?) honestly I havent used RA in ages...

[buttersoft]

In my experience, having a CRT display 240p or 480p with scanlines at ~80% intensity yields essentially the same result. ** I can post camera shots showing that.

Moreover, by running your CRT at 120Hz with your content only being 60fps you either end up with jerky motion due to uneven cadence (like Mike Chi experienced in the video you linked) or increased motion blur due to higher persistency (every frame will be displayed twice, but the phosphors decay is a fixed 1 or 2ms, meaning that every row will stay on-screen for double the time). Or both actually.

(this is assuming that emulation is capped at the original fps, which should be the case)

** More precisely, a CRT with 0.25mm AG pitch

At ~6:15 in the video though, Mike corrects the jerky motion with a setting in the monitor's menu. Not sure about blur, but he seems happy with motion after that.

[karmeck]

In vanilla MAME you can just use small overlays of just the required pixel height (and whatever width you desire) matching the integer factor of the game system source.
You can then assign a specific png to each system using .ini files. Per driver is the fastest way, only need to make a handful.

Dunno if it's doable with your thing though, RetroArch and alike remove a number of useful controls from MAME.

EDIT: you'll never find a single overlay that adapts to all game hardwares as Ben underlined, you'll need to have a number of those but if RA doesn't let you assign overlays per hardware like vanilla MAME using ini files, mayve there's another way? (per game?) honestly I havent used RA in ages...

Like this :
https://github.com/recalbox/recalbox-os ... rlays-(EN)

[karmeck]

The comments to this reddit post offer additional options:
https://www.reddit.com/r/emulation/comm ... _your_vga/

[Xyga]

Like this :
https://github.com/recalbox/recalbox-os ... rlays-(EN)

the link didn't work but that led me to it anyway thanks

it doesn't tell if it can be done per mame hardware though (like cps2.zip.cfg or toaplan2.zip.cfg for instance)

by game is kinda tedious but heh

[karmeck]

So here is with integer scale on. Same 960p overlay as befor.

Width 5x
Hight 3x

Spoiler

Looks good if you ask me. Lines just between the pixels.

Can't go any bigger on Hight. Why is that? Should I not be able to go 5x on both?

[Xer Xian]

At ~6:15 in the video though, Mike corrects the jerky motion with a setting in the monitor's menu. Not sure about blur, but he seems happy with motion after that.

Yes, what he does (i.e. setting 'swap interval' to 2) locks the frame rate to 60fps (or more precisely, synchronizes the frame buffers swap in a better way) which I guess ensures a solid 2:2 cadence (every frame is repeated twice). But having repeated frames increases motion blurs on CRTs - assuming a motion of 1000 pixel per second, every additional millisecond of same-frame visibility adds 1 more blurry pixel (you can head to the BlurBusters website for more on this). Might be counter-intuitive, but you can only blame human's vision system for it

[BazookaBen]

Can't go any bigger on Hight. Why is that? Should I not be able to go 5x on both?

Not sure, but 3x240 is 720. So maybe you should make a 960x720 custom resolution so it takes up your whole screen. Or for 224p SNES games, 672p (not sure about horizontal, you'll need to look that up for the individual game and multiply by 3 or whatever).

But yeah, those screenshots look pretty good to me. I guess the only issue is that they might be windowboxed (not using your full screen)?

[karmeck]

Can't go any bigger on Hight. Why is that? Should I not be able to go 5x on both?

Not sure, but 3x240 is 720. So maybe you should make a 960x720 custom resolution so it takes up your whole screen. Or for 224p SNES games, 672p (not sure about horizontal, you'll need to look that up for the individual game and multiply by 3 or whatever).

But yeah, those screenshots look pretty good to me. I guess the only issue is that they might be windowboxed (not using your full screen)?

Think that is a geometry "issue" I have yet to edit that. I use "" as this thing is freaking grate, just have to edit the width, other then that no geometry issues.

[BazookaBen]

Think that is a geometry "issue" I have yet to edit that. I use "" as this thing is freaking grate, just have to edit the width, other then that no geometry issues.

That's the good thing about Trinitron monitors, you can change the width/height in the menu, and it will save it for next time you use that resolution. So all you really have to do is get your width and height within striking distance on your emulator, then you can eliminate the rest of the underscan with your P991's OSD controls.

[Xer Xian]

Sorry for bumping this, but I wanted to add one last bit to the 120hz@60fps thing..

But having repeated frames increases motion blurs on CRTs - assuming a motion of 1000 pixel per second, every additional millisecond of same-frame visibility adds 1 more blurry pixel (you can head to the BlurBusters website for more on this).

I actually looked up about this on their forums myself and it appears there's more to it than that - having a refresh rate that's twice the frame rate causes a double-image effect on CRTs..
https://forums.blurbusters.com/viewtopic.php?f=2&t=342
https://forums.blurbusters.com/viewtopic.php?f=2&t=680

What I think happens is that when your eyes are tracking an object that's moving across the screen and appears twice in the same position, to your moving eyes that will appear as not one but two equal objects next to each other, separated by the same distance the eyes have covered in between the two (equal) frames! And that's how you get LCD-like motion blur on CRTs I guess..

[karmeck]

And that's how you get LCD-like motion blur on CRTs I guess..

That's sounds bad, but I dose not look that vad in the video. Or is this something that is technically correct but practically impossible to see.

[BazookaBen]

That's sounds bad, but I dose not look that vad in the video. Or is this something that is technically correct but practically impossible to see.

It is actually quite noticeable. Set your CRT monitor to 120hz (you can do this at 1024x768 and below on a P991) and go https://testufo.com/

The top ufo will be 120fps, bottom one will be 60fps. The 60fps one leaves a slight double image (not nearly as bad as 30fps at 60hz though).

So blur is the wrong term, it's more of a double image. It's not terrible, but it's far from 60fps at native 60hz.

[karmeck]

Upon further inspection:

Spoiler

That's the upprepa right corner. And if I fix that guess what happens on the other side.

[buttersoft]

thanks for the tips on the double-image effect at 120Hz, interesting stuff