GaryMcT's Mame CRT simulation project

[GaryMcT]

Just starting to work on this.  I'm really busy at work, and I have other projects in the works here, but I figure I'll try to spend a little bit of time on this soonish.

Basically, I want to modify Mame to emulate the look of an arcade CRT display using D3D9 pixel shaders.  I have a Wells Gardner D9500 sitting next to my first-gen 1920x1200 Apple Cinema Display.  The blacks on the Cinema Display aren't great, but I can try to get them to look similar.  This LCD may not be high enough resolution to be able to do it well, but I'll give it a try.

My test case is Pac-Man.  It originally runs at 224x288.  The CRT and LCD are about the same height.  Assuming I'm going to be looking at the images sideways, the image will be cropped on the left and right on the LCD.  I end up with 1200/224 LCD pixels in one dimension for every CRT pixel.  That give me a little more than a 5x5 pixel array on the LCD to emulate a pixel on the CRT.  I'm not sure if this is enough to do a good job, but I'll give it a try.  I have higher DPI monitors at work that I can look at this well.

I'm going to start off by running some test patterns on the CRT to see what the pixels actually look like on there.  I'll start with a single white pixel and single red, green, and blue pixels.  Hopefully I can borrow my wife's DLSR camera and a little tripod to get some shots of what the falloff function looks like.  I'll likely use tweaks of these shots to get images to use as textures for the pixel shader to use to model the pixel falloff on a CRT.

This'll probably take me a while. . I'm very very busy at work.

[DJ_Izumi]

I think your first issue is that arcade CRT monitors don't use 1:1 square pixels where as your LCD does.  That would present issues with getting the aspect ratio right.  Which puts a wrench into the idea that you have 5x5 to use per pixel.

[GaryMcT]

I'm not going to be doing any one to one pixel operations on the output.  I'm just trying to get an idea of how many output pixels per every input pixel I roughly have to try to emulate the pixel function of the CRT.  There is probably overlap between pixels as well.

[Applekid]

Visualizing it, I can see a massive number of "phosphor pixel" point sprites each with a color phosphor and glow. They all decay at different rates as that chart in the last thread showed.

I'm not sure they'd be perfect 1-1 anyway. Definitely definitely need to think in subpixels and the shadow mask of the color monitor, and a tracing beam. The amount of operations per second to get it right.... wow.... Refresh seveal times the number of raster rows for every one emulated CRT row to the tune of at least 60 (x emulation accuracy) per second.

Good thing we've got 200 GHz 256-core CPUs, right? 

[GaryMcT]

A dx9 ps20 pixel shader should be able to do it without a problem on the GPU.

[Ond]

Very useful project!  I just use the existing available filters for Mame to try to get that 'look' on my LCD but that system could always be improved on with your idea.

[DolansCadillac]

Seriously Gary if you get this going, I'll gladly Paypal you cash for beers. I've been looking for anything that taps GPU to adjust display output positively for a while, and I don't even know how to start coding a shader.

Not sure if it's of any help to you with your efforts but the best solution I've found so far is a custom D3D library called ENBSeries (http://boris-vorontsov.narod.ru/download_en.htm) - apparently people use them with popular PC games to add more dramatic looking lighting effects. I grabbed the version made for Oblivion to test with. The library simply needs to be in the same folder as the MAME executable, and it loads immediately on launch without any additional instruction (it's labelled d3d9.dll, I guess that acts as an override to the regular Win library). Also it will reference additional shader instructions in files labelled effect.txt, which looks like raw shader code. I paired the Oblivion version with the effect.txt file included for Guilty Gear, and after a lot of tweaking to both config files it uses I'm not satisfied enough to recommend it, but I really think there's potential there. I definitely like what it does for color adjustment, although the huge amounts of saturation is pretty ridiculous, and the bloom effect is interesting in very tiny amounts. It also adds a nice-looking color grading effect to the edges of the screen.

The downsides though are pretty bad - color bleed seems to work in reverse at times, with dark colors badly tinting bright surrounding colors (Rolling Thunder and 1943 show this right away) and as I said I can't wrangle the saturation down without cranking down gamma to unacceptable levels. That said, some games definitely look improved because of it.

I'll get some screenshots and my settings for you if you think it'd be useful at all. Thanks for taking this on.

[Ummon]

Fascinating.

[Blanka]

http://forum.arcadecontrols.com/index.php?topic=89791.msg966608#msg966608
Here I tried some filters in Photoshop that preserve the brightness and contrast, yet make a decent scanline image on LCD's.

[GaryMcT]

I'm interested in actually getting the offset dot pattern that you get on a CRT.

I probably won't have much to update for a while since I'm busy busy at work.

[Malenko]

not to be anal , but wouldnt it be a CRT simulation?

there's people like chad and jim in the world that'll ---smurfette--- and moan if you say emulation and mean simulation :p

[GaryMcT]

I'm trying to emulate the look of a CRT.  I'm not sure where this super-anal differentation between emulation and simulation came from.  Here's what the Computer Dictionary has to say. . seems unclear to me:

emulation architecture
When one system performs in exactly the same way as another, though perhaps not at the same speed. A typical example would be emulation of one computer by (a program running on) another. You might use an emulation as a replacement for a system whereas you would use a simulation if you just wanted to analyse it and make predictions about it.

simulation simulation, system
Attempting to predict aspects of the behaviour of some system by creating an approximate (mathematical) model of it. This can be done by physical modelling, by writing a special-purpose computer program or using a more general simulation package, probably still aimed at a particular kind of simulation (e.g. structural engineering, fluid flow). Typical examples are aircraft flight simlators or electronic circuit simulators. A great many simulation languages exist, e.g.

[Malenko]

I'll just say Im fine with what you call it, but when chad or jim or some others see it, they'll be...well, themselves, lol

I look forward to it, I dont really like the look of MAME on a LCD so this will give me one less reason to get a hernia keeping it "authentic"

[solid12345]

Of course we will get bitching, as people have for a few years, there is no reason a decent CRT "simulator" for MAME couldn't have been done ages ago but people find some reason to ---steaming pile of meadow muffin--- on a project before it even gets off the ground, almost as if no one has the "right" to make gaming experience on an LCD better, look at how much crap those developers behind the Intellevision CRT project got, and what for, for trying to do something cool?

And don't play the card that you are not a true enthusiast if you are not out there hoarding every last 19'' CRT left, some of us also MAME on laptops or our PC besides owning a setup, what is wrong with wanting to somewhat mimic the experience on these as well?

[GaryMcT]

I'm a CRT hoarder myself, and one of mine died recently.  This is why I want this to work on an LCD.

On a related note, I'd also like to implement a decent vector simulation (<---- see, I'm using the right word now! ), but it might not work so well quite yet since most modern displays aren't as high-contrast as a vector display.  I have real vector monitors at home to user as reference.  I don't have color vector monitors at home, but I do have an Asteroids Deluxe and an Omega Race.  The color ones actually look quite different with the shadow mask.  I may have to pick up a color vector machine for comparison.

[GaryMcT]

I renamed the thread.

[Malenko]

I renamed the thread.

hahaha, well I subscribed to it, I cant wait!

[MaximRecoil]

Even if you manage to simulate the look of a course triad shadow mask and dot pitch, you still have a few problems which are inherently insurmountable with LCD displays.

For one thing, LCDs are backlit, while CRTs generate their own light. This gives an inherently different look to the light.

For another thing, the spectrum you see when viewing an LCD changes with viewing angle (this happens to one degree or another with all LCDs, despite claims that this problem has been solved).

Also, LCDs have a thin plastic screen, which has different properties with regard to how light passes through it and reflects off it than the thick glass of a CRT.

This all adds up to a baseline look that is inherently different than the baseline look of a CRT. No matter what image you generate with an LCD it will never look like a CRT. To prove this, you could take some perfectly framed high-definition video of a standard arcade monitor displaying e.g., a game of Pac-Man (preferably matching the video frame rate with the monitor's refresh rate). Now play that video back on an LCD display of your choice, and see if you are fooled. That same video played back on a CRT PC monitor however could be pretty convincing. So if you are able to accomplish such a simulation, I'd be interested, because I still use a CRT PC monitor, and I will continue to do so for as long as possible; or until something that is truly as good or better comes along (I'm not a fan of "one step forward, two steps back" technologies such as LCD).

[Bender]

MaximRecoil,

that is true but a CRT is just not an option for every application
This just supposed to be "as close as we can get" to a CRT look on the admittedly inferior an LCD, not to replace CRT's

I have to say, behind smoked glass, my LED LCD looks pretty darn good (the blacks are much better) again I'm not saying it's CRT quality, but a 19" CRT is bigger than my whole project

I can't believe Gary hasn't even started this in earnest yet and people are poo pooing it
Gary PLEASE don't let anyone keep you from making this!!!!

[solid12345]

Like Bender said, this is not about replacing CRT's, just replicate as much as you can.

I truly think it CAN be done, I mean if you sat with a good digital camera on a tripod and took a screencap of a CRT screen and viewed it fullsize on an LCD it looks pretty good, granted you'll never captured the depth of a bulbous thick glass screen of a CRT or the seemingly floating pixels in the dead of black but I do think with the right programming you can at least make something that looks better than the ugly blotchy stairstep effect you get with MAME as of now.

[GaryMcT]

I'm not trying to replace CRTs.  When I have to run Mame on an LCD, plasma, etc. device, I want it to look better than it does now.  Also, I wouldn't mind being able to have a single machine that I can play CRT and vector games on without one of them looking completely awful.

[DJ_Izumi]

I still think that if high resolution progressive LCD screens were an option in the 70's and 80's, arcade devs woulda totally used them.

[GaryMcT]

I still think that if high resolution progressive LCD screens were an option in the 70's and 80's, arcade devs woulda totally used them.

I think they would have use them, but they would have designed their art much differently than they did for shipping on a CRT.

I work on games now, and we go out of our way to author our content so that it looks good on the platform we are delivering it on.  For instance, if we know that we aren't going to be able to run with MSAA at 720p on a 360, we try to not author our models with high-frequency detail so that it doesn't alias/shimmer like mad.

[MaximRecoil]

I still think that if high resolution progressive LCD screens were an option in the 70's and 80's, arcade devs woulda totally used them.

The game hardware wasn't capable of high resolution raster graphics back then, so what would be the point of using a high resolution monitor? Games with a native resolution in the neighborhood of 320 x 240 look like crap when distorted/scaled/stretched/filtered to fit an LCD display's native (and fixed) resolution of say 1024 x 768 or higher. Additionally, the games would have looked incredibly blocky. For example, instead of the Pac-Man character looking like a circle, it would have had noticeable jagged stairstepping all around it.

[CheffoJeffo]

TMK, Maxim is correct in everything he said.

Instead of labeling him as Mr PooPoo, perhaps you should take in what he is saying. Yhe question is whether the software changes can overcome the hardware differences (some of which Maxim has been the only one to point out).

The defenders say yes ... and they may be right ... but they may not be.

In either case, Maxim seems to be genuinely interested in the potential and is just providing technical info.

Do we need to call the Belligerent KoolAid man back or can we keep the discussion rational ?

 

[GaryMcT]

Seems like a rational discussion to me.

[CheffoJeffo]

Seems like a rational discussion to me.

But I liked the irrational discussion so much more ... 

In all honesty, I think what you are doing could be interesting, but I would want to use a CRT and think the results there could be pretty good.

From what I hear from the locals, RickN has done some cool stuff with LCDs as drop-in replacements for classic arcade monitors. You might want to look at what he is doing (I haven't looked into it at all at this point, so it may not be applicable).

[TheShanMan]

Games with a native resolution in the neighborhood of 320 x 240 look like crap when distorted/scaled/stretched/filtered to fit an LCD display's native (and fixed) resolution of say 1024 x 768 or higher.

Maybe I'm not picky or something, but my mame cab uses a flat screen trinitron at 1280x1024 and to me at least, the games look quite good. Authentic? Not quite, but certainly not "crap" by any means.

[DJ_Izumi]

The game hardware wasn't capable of high resolution raster graphics back then, so what would be the point of using a high resolution monitor? Games with a native resolution in the neighborhood of 320 x 240 look like crap when distorted/scaled/stretched/filtered to fit an LCD display's native (and fixed) resolution of say 1024 x 768 or higher.

Well, any low resolution content tends to get distorted by using upscaling unless it's in exact multiples.  For example, a 320x240 game would look GREAT on a 640x480 screen.  They'd just use blocks of 4 pixels for every one pixel of ingame data.  But even CRTs can have this issue.  Daytona USA runs at 496 x 384, so any standard resolution on a PC distorts the 2D sprites.  I instead specificlly added the 496 x 384 resolution to the driver.  Though I then decided I wanted higher res 3D.  I added 992 x 768, which is double the dimensions of 496 x 384.  As a result the 3D graphics were at much higher resolution and the 2D sprites remained crisp and clear.

I surmise that if higher resolution LCDs were available in the 70's and 80's there would be a lot of custome variations.  Keep in mind there'd also be the entire PC industry to cater to as well.  I think there'd be plenty of 'low resolution' LCD monitors on the consumer market and far more specific monitors available to industry, including the computer and arcade industries.  They could likely easily order monitors custom to their resolution needs.

Though this isn't so much my point.  My point is, if arcade devs could use higher quality displays at the time, they would have and they would have been like 'HELL YEAH!  Look how sharp and clear that is!  It doesn't even flicker!  This is awesome.'  I find a lot of older arcade or console games refreshingly clean looking on a PC monitor. 

[MaximRecoil]

Maybe I'm not picky or something, but my mame cab uses a flat screen trinitron at 1280x1024 and to me at least, the games look quite good. Authentic? Not quite, but certainly not "crap" by any means.

"Crap" is a relative term of course. When I use MAME on my PC, it is at 1152 x 864 on a 22" Mitsubishi Diamondtron. It doesn't make my eyes bleed or anything, but it looks nothing like a standard arcade monitor (it is pasty smooth and blocky).

[MaximRecoil]

Well, any low resolution content tends to get distorted by using upscaling unless it's in exact multiples.  For example, a 320x240 game would look GREAT on a 640x480 screen.

In that example, only the distortion issue is eliminated, but that doesn't automatically make it look great. Low resolution graphics on a high resolution screen with a fine dot pitch look bad. It is like the "screenshots" they used to put on the boxes for some of the older console games; which weren't screenshots at all, but artist renditions, done with razor sharp square pixels:



Fortunately when you got it home and played it, it looked nothing like that on the TV screen. However, fire up SMB in an emulator on a high resolution PC monitor, and it looks exactly like that.

I surmise that if higher resolution LCDs were available in the 70's and 80's there would be a lot of custome variations.  Keep in mind there'd also be the entire PC industry to cater to as well.  I think there'd be plenty of 'low resolution' LCD monitors on the consumer market and far more specific monitors available to industry, including the computer and arcade industries.  They could likely easily order monitors custom to their resolution needs.

Though this isn't so much my point.  My point is, if arcade devs could use higher quality displays at the time, they would have and they would have been like 'HELL YEAH!  Look how sharp and clear that is!  It doesn't even flicker!  This is awesome.'  I find a lot of older arcade or console games refreshingly clean looking on a PC monitor. 

I'm not convinced that they would have been impressed with their graphics looking like Lego blocks. Also, what do you mean by "higher quality" displays? The popular arcade monitors of the day were not lacking in quality.

[DJ_Izumi]

Higher quality as in image quality.

[MaximRecoil]

Higher quality as in image quality.

If you mean "image quality" in the technical sense; which would be the level of trueness to the source, then only an LCD with a native resolution that exactly matches the resolution of the game being displayed could be said to have better image quality than a standard resolution arcade monitor; and even then, that would only be in one respect (how accurate the shapes are). What happens when I change my viewing angle while viewing an LCD display? I see different colors. Whoops! How true is that to the source? The source has a hard coded color for each pixel; not variable depending on one's viewing angle.

But the more important issue is this; what if the source is ugly, and through the inherent effects of a standard resolution CRT, that ugliness can be improved? I submit, for example, that a round Pac-Man sprite is more aesthetically pleasing than a Lego block Pac-Man sprite. If a cartoonist or comic book artist were to draw Pac-Man, it would be with smooth curves; because that looks better than jagged edges. When Iwatani envisioned the character, he no doubt envisioned a circle. The Pac-Man hardware forced Lego blockesque data, but it didn't matter; because when viewed on an arcade monitor, Pac-Man looked like a circle nonetheless.

A similar situation comes up when discussing sound quality (trueness to source). What if the recording sounds bad due to an incompetent sound guy in the studio? If you fix it via e.g. an equalizer so that it sounds better, technically you have worse sound quality (less true to the source), but it sounds better. Which would you choose?

[GaryMcT]

Maybe the debate about whether or not this a worthwhile project could be taken somewhere else?  I'm doing the project, so it isn't really helpful to debate whether it is useful to anyone or not. 

[MaximRecoil]

Maybe the debate about whether or not this a worthwhile project could be taken somewhere else?

Who's debating about whether or not this a worthwhile project? I've already stated this:

So if you are able to accomplish such a simulation, I'd be interested

[John IV [MameUI64]]

Seen this?

http://board.byuu.org/viewtopic.php?f=10&t=147&sid=968e403a218d0f59b4e454df44ef2409

[drventure]

This sounds like a really cool project.
Honestly, I don't think Mame on a decent LCD looks all that bad, but, I suppose there's always some room for improvement (or maybe my eyes are just shot  )

[GaryMcT]

This sounds like a really cool project.
Honestly, I don't think Mame on a decent LCD looks all that bad, but, I suppose there's always some room for improvement (or maybe my eyes are just shot  )

I hadn't seen that.  That looks really interesting!  I'll have a look later when I'm at home.

Thanks!

[smalltownguy]

Seen this?

http://board.byuu.org/viewtopic.php?f=10&t=147&sid=968e403a218d0f59b4e454df44ef2409

I had no idea THAT project was so far underway. I'm watching this closely -- I'd really like to see what kind of result this will give me on a projector display.

[GaryMcT]

Did they ever get a real implementation?

[Xiaou2]

 That was much better than some others Ive seen... However... as always,
nobody seems to get color mixing / blending  into the equation.

 Also, they are not comparing actual pictures of a TV or Arcade monitor against
the results.