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 Post subject: Re: Emulation Shader recommendations
PostPosted: Wed Oct 31, 2018 8:06 pm 


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Location: zip code 20151 USA
Chocograph wrote:
I've looked at the PI models because I wanted one of those too but I was just checking prices on ebay. I have zero clue how to set it up and I can only speculate (or google) about the input lag. Input lag is a huge deal for me. It's why I got the framemeister so I could put away the crt. I might get a PI one day. It's got cool cases.

Maybe this link will help a bit..
https://www.arcade-projects.com/forums/ ... er-device/
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 Post subject: Re: Emulation Shader recommendations
PostPosted: Wed Oct 31, 2018 11:33 pm 



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Posts: 92
I spent a lot of time looking into this thinking I could ditch a real BVM (the answer was no, but still nice to have this option). For the perfect BVM look nothing else comes close to the Kurozumi preset CRT Royale. Here's a few tips that I learned through annoying trial-and-error:

1. Confusingly, you won't find the Kurozumi-crt-royale shader in the CRT folder along with the base crt-royale shader, but instead in the folder called "presets".
2. Don't use the .glsl version, since it is glitched. Instead, use the .slang version (.cg shaders are deprecated now, but you can try that if you're on nvidia and nothing else works).
3. To use .slang you need to switch your video driver in Retroarch from GL to Vulkan.
4. If you're using a 4K display, open the .slang file with a text editor and look for the setting called "Mask_triad_size_desired", and change its value from the default 1 to 0 (or you can also try 3). This is very important because it allows to emulate the extremely fine aperture grill of a BVM of around 900/1000 lines. It looks even better on a 5K display if you have one. The setting of 1 is a left over from when 1080p displays were the norm.
5. This all assumes you're running Retroarch on Windows (and you don't need a super powerful machine for this to run smoothly). Vulkan is not available on Mac and the GL shader does not work.

You can find more info on this amazing shader here:

https://forums.libretro.com/t/crt-royal ... p/3909/300


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Thu Nov 01, 2018 4:07 pm 



Joined: 01 Sep 2018
Posts: 12
fernan1234 wrote:
I spent a lot of time looking into this thinking I could ditch a real BVM (the answer was no, but still nice to have this option). For the perfect BVM look nothing else comes close to the Kurozumi preset CRT Royale. Here's a few tips that I learned through annoying trial-and-error:

1. Confusingly, you won't find the Kurozumi-crt-royale shader in the CRT folder along with the base crt-royale shader, but instead in the folder called "presets".
2. Don't use the .glsl version, since it is glitched. Instead, use the .slang version (.cg shaders are deprecated now, but you can try that if you're on nvidia and nothing else works).
3. To use .slang you need to switch your video driver in Retroarch from GL to Vulkan.
4. If you're using a 4K display, open the .slang file with a text editor and look for the setting called "Mask_triad_size_desired", and change its value from the default 1 to 0 (or you can also try 3). This is very important because it allows to emulate the extremely fine aperture grill of a BVM of around 900/1000 lines. It looks even better on a 5K display if you have one. The setting of 1 is a left over from when 1080p displays were the norm.
5. This all assumes you're running Retroarch on Windows (and you don't need a super powerful machine for this to run smoothly). Vulkan is not available on Mac and the GL shader does not work.

You can find more info on this amazing shader here:

https://forums.libretro.com/t/crt-royal ... p/3909/300


Although I appreciate the immense effort that goes into such shaders as Kurozumi, I question the goal and motivation. Why are we trying to replicate every single feature of a CRT? Do we REALLY need every simulated phosphor to have a slight red tinge at one end just because that's how it was on a BVM (for example)? How are we justified in saying that "this particular CRT represents the absolute pinnacle in objective picture quality for 240p content?" IMO we are never justified in making such a claim, it's arbitrary and somewhat silly. Trying to replicate everything a CRT does isn't desirable from the standpoint of picture quality, and it comes with a very high performance cost. A better approach is to start by asking "What is a CRT doing to the image, fundamentally? What qualities of the CRT actually enhance the objective picture quality?" and proceed from there. Personally, I don't understand the need for CRTs any more now that there's 0 input lag in Retroarch. You can get better objective picture quality than any CRT if you have a 1440p display with HDR (or better yet, 4k), along with the right shader settings (see my previous post). Then again, I'm not interested in replicating CRT artifacts like color bleed, only the aspects that improve the image. Nostalgia and "authenticity" aren't important factors for me.

It is now possible to get better objective picture quality than what one gets on a BVM with the right display and the right shader settings, but it takes a very good display- at least 1440p resolution and HDR are required. Of course, CRTs still have better viewing angles and non-existent motion blur, but in terms of contrast, color, brightness, and image uniformity- the right display with the right settings blows away a BVM.


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Thu Nov 01, 2018 4:31 pm 



Joined: 14 Aug 2017
Posts: 92
Patrickbot wrote:

Although I appreciate the immense effort that goes into such shaders as Kurozumi, I question the goal and motivation. Why are we trying to replicate every single feature of a CRT? Do we REALLY need every simulated phosphor to have a slight red tinge at one end just because that's how it was on a BVM (for example)? How are we justified in saying that "this particular CRT represents the absolute pinnacle in objective picture quality for 240p content?" IMO we are never justified in making such a claim, it's arbitrary and somewhat silly. Trying to replicate everything a CRT does isn't desirable from the standpoint of picture quality, and it comes with a very high performance cost. A better approach is to start by asking "What is a CRT doing to the image, fundamentally? What qualities of the CRT actually enhance the objective picture quality?" and proceed from there. Personally, I don't understand the need for CRTs any more now that there's 0 input lag in Retroarch. You can get better objective picture quality than any CRT if you have a 1440p display with HDR (or better yet, 4k), along with the right shader settings (see my previous post). Then again, I'm not interested in replicating CRT artifacts like color bleed, only the aspects that improve the image. Nostalgia and "authenticity" aren't important factors for me.

It is now possible to get better objective picture quality than what one gets on a BVM with the right display and the right shader settings, but it takes a very good display- at least 1440p resolution and HDR are required. Of course, CRTs still have better viewing angles and non-existent motion blur, but in terms of contrast, color, brightness, and image uniformity- the right display with the right settings blows away a BVM.



I agree that it's unnecessary to replicate the slight convergence imperfection that the shader's author seems to favor, but you can easily change those settings to 0 to get the picture of a theoretically 100% perfect convergence CRT (in my case that's what I chose to do in the end too).

There's really no performance cost issue at all with any recent PC I would say. I could run the shader perfectly on a 2017 iMac running Windows, so people with gaming PC setups would not even need to think about it.

I will disagree with the statement that options that "blow away" a CRT BVM are available, at least for people who don't have 20,000 bucks to blow on an OLED BVM. I've tried a lot of things precisely because I do not want to need a CRT, but always end up concluding that sadly the options are just not there. Resolution is important, but 1440p will not cut it. 4K barely does, but we will need at least 8K to really emulate a CRT perfectly. In terms of picture quality for SD content (i.e. most of what we play), I've never seen an LCD of any kind that comes even close to a CRT BVM. An OLED 4K does beat CRT in several picture quality aspects, but when it comes to replicating these old games (where HDR does not factor into the equation in the first place), it's actually a shame that such a great technology still falls short on things that matter so much for gaming, mainly motion resolution (and black frame insertion can only do so much, we're still at least a decade away from the refresh rate that will be needed to match CRTs). In terms of overall picture quality, the only things I could see right now beating a CRT BVM are other BVMs (perhaps the Trimaster LCD ones, and most certainly the newer true RGB OLED ones), though even these would have the limitations inherent to sample-and-hold displays.

In any case, having tried both options side by side, I do think that a currently available consumer WRGB OLED display using the Kurozumi shader (with some values changed as mentioned before) can be a very satisfactory (but not superior) alternative to a CRT BVM.


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Fri Nov 02, 2018 9:56 am 



Joined: 13 Aug 2018
Posts: 6
Patrickbot wrote:
You can get better objective picture quality than any CRT if you have a 1440p display with HDR (or better yet, 4k), along with the right shader settings (see my previous post). Then again, I'm not interested in replicating CRT artifacts like color bleed, only the aspects that improve the image. Nostalgia and "authenticity" aren't important factors for me.

It is now possible to get better objective picture quality than what one gets on a BVM with the right display and the right shader settings, but it takes a very good display- at least 1440p resolution and HDR are required. Of course, CRTs still have better viewing angles and non-existent motion blur, but in terms of contrast, color, brightness, and image uniformity- the right display with the right settings blows away a BVM.


When it comes to 240p content, there is no such thing as "better objective picture quality", it all comes down to preference. Some people love how high-end BVMs handle 240p content, others don't. No one is right or wrong here. The Kurozumi shader is fantastic when it comes to replicating that BVM-look, and is a really good alternative if you don't want to shell out 1K$+ for a BVM.

Patrickbot wrote:
contrary to some sources, ideal scanlines are closer to a 2:1 ratio than a 1:1 ratio

Again, this is a subjective opinion, not an objective one.

I happen to own a BVM and a 4K OLED. The picture quality of 240p on the BVM is both sharper and brighter than Kurozumi running on the OLED. The BVM also has zero input lag. The OLED can't compete with that, even when running Retroarch's low latency function. I prefer the BVM, but the Kurozumi is still amazing. Will this change when we in 5-8 years have access to 8K OLED's with zero input lag (fingers crossed) and higher brightness? I don't know, maybe, but as nostalgia and "authenticity" are important to me I will probably still prefer the BVM.


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Fri Nov 02, 2018 4:01 pm 



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Quote:
When it comes to 240p content, there is no such thing as "better objective picture quality", it all comes down to preference. Some people love how high-end BVMs handle 240p content, others don't. No one is right or wrong here. The Kurozumi shader is fantastic when it comes to replicating that BVM-look, and is a really good alternative if you don't want to shell out 1K$+ for a BVM.


Of course there is such a thing as "objective picture quality." It's the same definition that's always applied. Of course, I respect that many people aren't necessarily trying to achieve objective picture quality, but that doesn't mean that objective picture quality doesn't exist.

Just because something may be hard to define, doesn't mean that it's automatically "subjective."

I'm certainly not trying to denigrate other people's choices, but there is definitely such a thing as "objective picture quality." To attempt a working definition: It's the same when discussing any other video format - you want to display all of the information in the video signal at the resolution that it's meant to be displayed at, while introducing as few artifacts as possible. For 240p content this means scanlines are mandatory, because they're an essential defining feature of the format (a 240p image without scanlines can't be distinguished from the same image that has been line doubled to 480p). Some may think you can just apply scanlines and then you're done, but when upscaled to 1080p using nearest neighbor, you're displaying the content at close to 3x the resolution that it was intended to be displayed at. You also have to replicate the phosphor structure/lower TVL of a CRT to replicate the intended screen environment.


Quote:
Patrickbot wrote:
contrary to some sources, ideal scanlines are closer to a 2:1 ratio than a 1:1 ratio

Again, this is a subjective opinion, not an objective one.



Edit: I stand corrected; “perfect” scanlines, such as would appear on a hypothetically perfect CRT, are in fact 1:1 when discussing *objective* brightness. Each visible line being twice as objectively bright results in them being *perceived* as 1.4 times as bright. Either way, both objective and perceived brightness should be the same for 240p vs 480i.

Quote:
I happen to own a BVM and a 4K OLED. The picture quality of 240p on the BVM is both sharper and brighter than Kurozumi running on the OLED. The BVM also has zero input lag. The OLED can't compete with that, even when running Retroarch's low latency function. I prefer the BVM, but the Kurozumi is still amazing. Will this change when we in 5-8 years have access to 8K OLED's with zero input lag (fingers crossed) and higher brightness? I don't know, maybe, but as nostalgia and "authenticity" are important to me I will probably still prefer the BVM.


I wonder if your display has HDR, and if you're actually using it when running the emulator. AFAIK there is no way for the user to call on HDR manually, except through Windows, and that's still less than ideal. Theoretically, a display with HDR is orders of magnitude brighter than a CRT, which means we can do an accurate RGB mask and scanlines while still easily achieving CRT-like luminance.

I believe you that Kurozumi on the OLED isn't as sharp as the BVM, because almost all shaders add blur as a way to deal with scaling artifacts from non-integer scaling. The solution is to always use nearest neighbor and integer scaling. You lose the perfect 4:3 AR, but you can still get pretty close to 4:3, and CRTs never had perfect geometry, anyway. Unless there's blur being added somewhere, a digital display should always be sharper than even the sharpest CRT.

Retroarch in 2018 is capable of lower input latency than the actual hardware, using the "run ahead" feature, but it's still not perfect.

Again, not trying to denigrate other's choices, just offering a different perspective, and one which I realize falls outside of mainstream opinion.


Last edited by Patrickbot on Sat Nov 10, 2018 10:49 pm, edited 8 times in total.

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 Post subject: Re: Emulation Shader recommendations
PostPosted: Fri Nov 02, 2018 4:12 pm 



Joined: 01 Sep 2018
Posts: 12
fernan1234 wrote:

There's really no performance cost issue at all with any recent PC I would say. I could run the shader perfectly on a 2017 iMac running Windows, so people with gaming PC setups would not even need to think about it.


I'm thinking of Raspberry Pis, Intel NUCs, phones, and such. There are a lot of devices that people run emulators on these days besides gaming PCs.

Quote:
I will disagree with the statement that options that "blow away" a CRT BVM are available, at least for people who don't have 20,000 bucks to blow on an OLED BVM. I've tried a lot of things precisely because I do not want to need a CRT, but always end up concluding that sadly the options are just not there. Resolution is important, but 1440p will not cut it. 4K barely does, but we will need at least 8K to really emulate a CRT perfectly.


1440p resolution is needed to do a proper RGB mask without running into problems with letterboxing and/or color bleed from using horizontal integer scales that aren't a multiple of 3. At 1440p you can run everything at 6x6 or 8x6 and have no artifacts and no letterboxing. So it's a significant upgrade from 1080p. I think you need 4k, and possibly 8k, to do a realistic halation effect, judging by macro photos of CRTs showing the individual phosphors.

Quote:
In terms of picture quality for SD content (i.e. most of what we play), I've never seen an LCD of any kind that comes even close to a CRT BVM. An OLED 4K does beat CRT in several picture quality aspects, but when it comes to replicating these old games (where HDR does not factor into the equation in the first place), it's actually a shame that such a great technology still falls short on things that matter so much for gaming, mainly motion resolution (and black frame insertion can only do so much, we're still at least a decade away from the refresh rate that will be needed to match CRTs).

In terms of overall picture quality, the only things I could see right now beating a CRT BVM are other BVMs (perhaps the Trimaster LCD ones, and most certainly the newer true RGB OLED ones), though even these would have the limitations inherent to sample-and-hold displays.



I agree that motion resolution is still a significant hurdle for current display tech, and an area where CRTs still reign supreme. However, it's an objective fact that most LCDs these days have superior black levels, contrast, and overall luminance. Luminance is actually still a limiting factor in CRT emulation, because of how much brightness is lost from scanlines and the RGB mask effect, but most current gaming displays have sufficient brightness to compensate. HDR will make this a non-issue.


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Fri Nov 02, 2018 4:55 pm 



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Posts: 92
The idea that I feel most sure about is that what the best display is, among what is available now, depends on the type of content to be displayed.

I can actually display 4K content on both a 1000-line widescreen BVM and a consumer HD CRT and let me tell you, it looks fantastic on both, but it definitely looks better on a 4K OLED. If I were to actually play HDR 4K content it may look better on some respects (there are multiple advantages to downconverting HDR to SDR), but of course you would lose all the punch of HDR by being limited to the 100 nits of an SDR display. 1080p content is kind of a tossup, but anything 1080i, 720p and below invariably looks better on a CRT BVM than on the OLED (there is no need to talk about LCD because OLED beats it on everything besides peak brightness, which is irrelevant for SDR content).

That said, I highly encourage people to try out the Kurozumi shader with the convergence and triad size tweaks on a 4K display, or, better, on a 5K one. Combining this shader with a 4K OLED + black frame insertion (by the TV, not by Retroarch) actually produces amazing results that may convince some to ditch their CRTs forever. On my 5K display it actually looks like an idealized BVM, only falling short in sharpness compared to a D24, and of course you would also have to tolerate motion blur, but for games with little motion it could arguably be considered a real alternative to the best BVM ever made.

edit: of course you should also select integer scaling on the Retroarch settings, cores usually do a good job at using the right AR for a 4:3 look


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Fri Nov 02, 2018 7:56 pm 



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Posts: 12
fernan1234 wrote:
1080p content is kind of a tossup, but anything 1080i, 720p and below invariably looks better on a CRT BVM than on the OLED (there is no need to talk about LCD because OLED beats it on everything besides peak brightness, which is irrelevant for SDR content).


Are we talking with or without shaders? If you mean without shaders, then I agree that the CRT is hands-down the better option. If you mean with the right shader settings applied, I think it's debatable. The CRT is still superior in terms of motion resolution, but the OLED is superior in terms of contrast, black level, sharpness, screen uniformity, and peak brightness. So I think it may be most accurate to say that there is no single display type that is superior in all categories for all types of content. Everything is a compromise; ce la vie.

Also, peak brightness isn't entirely irrelevant for SDR content. If you're trying to do accurate CRT emulation, it can still be a limiting factor on many modern displays.

Quote:
That said, I highly encourage people to try out the Kurozumi shader with the convergence and triad size tweaks on a 4K display, or, better, on a 5K one. Combining this shader with a 4K OLED + black frame insertion (by the TV, not by Retroarch) actually produces amazing results that may convince some to ditch their CRTs forever. On my 5K display it actually looks like an idealized BVM, only falling short in sharpness compared to a D24, and of course you would also have to tolerate motion blur, but for games with little motion it could arguably be considered a real alternative to the best BVM ever made.

edit: of course you should also select integer scaling on the Retroarch settings, cores usually do a good job at using the right AR for a 4:3 look


Photos, please!

I'd love to give this a try, if only I had the hardware.

For a "lightweight" approach that will look good at 1080p and run on almost anything, the best I've been able to come up with is "image adjustment" + "zfast_crt" + "dotmask," with some modifications to the settings (see my post toward the bottom of the previous page).

This looks like an idealized 360 TVL CRT with no bleed / perfect convergence and perfect geometry. Some compromises had to be made with the mask in order to attain adequate luminance; the LCD just can't get bright enough even with the backlight maxed out.

I'd like to add a glow effect, but I need a 4k display for such an effect to look realistic while simulating a 360 TVL CRT, since it's the individual phosphors that glow.


Last edited by Patrickbot on Sat Nov 10, 2018 11:07 pm, edited 3 times in total.

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 Post subject: Re: Emulation Shader recommendations
PostPosted: Sat Nov 03, 2018 2:26 am 



Joined: 14 Aug 2017
Posts: 92
Sure, here are some pics. Make sure you see them in their original resolution (warning, huge pictures in spoiler tags):


@ 5K resolution direct screen captures (iMac IPS Panel) / 3 Pictures
Spoiler: show
Image

Image

Image


@ 4K resolution OLED TV via phone camera / 2 Pictures
Spoiler: show
Image
Image


4K, 5K, or 1000-line CRT? Which one is which? / 3 Pictures (these are probably best seen resized in the album)
Spoiler: show
Image

Image

Image



You can also see the pictures (resized) in the imgur album: https://imgur.com/a/3kd4WYI


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Sat Nov 03, 2018 6:52 pm 


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@fernan1234 - I have an OLED LG TV and would like to test this out.. would you mind sharing the shader file with the config that you are using on the OLED.. thanks
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 Post subject: Re: Emulation Shader recommendations
PostPosted: Sat Nov 03, 2018 8:46 pm 



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This shader is included with Retroarch, you just need to make at least one small change in the shader file to get the super fine aperture grille effect on a 4K display (to my eye it looks like a ~800 line BVM on 4K, about ~900 lines on 5K). Without this change the scanned lines (not the blank lines) will look solid, like when you use an OSSC with 100% "scanlines".

Just make sure you have updated the shaders through Retroarch. Then on Windows you can navigate to your Retroarch folder location, then follow this folder path: Retroarch > shaders > shaders_slang > presets > crt-royale-kurozumi.slangp

Open up that .slangp file with a text editor, look for the settings "mask_triad_size_desired" and change it from 1 to 3. If you want, also change all the "convergence_offset" settings that are not 0 to 0. Then save your changes, or save as a separate .slangp file to keep the original as a backup.

On Retroarch load your modified slang shader (you must have chosen Vulkan as your video driver on Retroarch to use slang shaders). You could also modify and use the .cgp version of the shader if you have to stick to the GL driver, but you may encounter a bug discussed here:
https://forums.libretro.com/t/crt-royal ... p/3909/293

There's more tweaks that can be done for stuff like diffusion and halation, but I never messed around with those. The author posted about it here:
https://forums.libretro.com/t/crt-royal ... p/3909/301


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Sat Nov 03, 2018 11:11 pm 


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Cool,,thank you!
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 Post subject: Re: Emulation Shader recommendations
PostPosted: Sun Nov 04, 2018 4:25 pm 



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Posts: 12
fernan1234 wrote:
Sure, here are some pics. Make sure you see them in their original resolution (warning, huge pictures in spoiler tags):


snip


Wow, those do look pretty great! That 5K screen looks amazing; very BVM-like.

Personally, I prefer a lower TVL for 240p content- around 400-500 is the sweet spot, with scanlines that are less than a 50% reduction in brightness per visible line. In particular, I don't like how dark colors on a BVM turn into razor thin lines that almost disappear, and the scanlines (black lines) are too harsh for extended periods of viewing IMO, causing eye strain.

For comparison's sake, it would also be interesting to see some shots with just the RGB mask and scanlines applied, with the scanlines being a perfect 1:1 (a 50% reduction in brightness per line) and the RGB mask strength increased to maximum, if and when you get the time. That's what I like, and what I consider "ideal" as far as CRT emulation on a digital display goes. No added blur/smoothing, no bloom, no bleed, no fake halation; just mask, scanlines, gamma correction, and (maybe) a slight amount of vertical blending between the scanlines. This is the closest to a real CRT that a digital display can get in terms of how it actually works.

which one is the 1000 line CRT:
Spoiler: show
Top: 4K
Middle: CRT
Bottom: 5K

:D


Last edited by Patrickbot on Sat Nov 10, 2018 10:25 pm, edited 1 time in total.

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 Post subject: Re: Emulation Shader recommendations
PostPosted: Tue Nov 06, 2018 10:02 pm 



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Posts: 92
Yep you got it right. All zoomed-in like that it's pretty obvious because you can recognize each panel's pixel structure, but in person and from a normal viewing distance they are remarkably similar, especially the 5K monitor and the BVM. Of course once things start moving it's a whole different story. I'm optimistic about the future though.

You can probably make all those tweaks you would like by modifying settings in the shader file.

Someone also made an XM29-like shader, which may be closer to your preferences, but I haven't tested it so I can't speak to its quality.


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Fri Nov 09, 2018 11:15 am 


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Patrickbot wrote:
In double strike mode (aka 240p), each visible line is drawn twice and then a line is skipped.

That's not correct. Each visible line is still only drawn once; the only difference is 240p does not alternate fields as 480i does, so every field is even or odd, instead of alternating. This accomplishes the effect of drawing every line on the same physical space of the tube. I am interested in how you derived your numbers, though (1.4 times and 30%), as they seem plausible. 2:1 ratio of scanline to "empty" space seems about right.

I think a precise calculation on brightness would have to incorporate Pi to estimate the falloff at the edges of a typical raster. I'm not a mathematician though.


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Sat Nov 10, 2018 7:59 pm 



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Ed Oscuro wrote:
Patrickbot wrote:
In double strike mode (aka 240p), each visible line is drawn twice and then a line is skipped.

That's not correct. Each visible line is still only drawn once; the only difference is 240p does not alternate fields as 480i does, so every field is even or odd, instead of alternating. This accomplishes the effect of drawing every line on the same physical space of the tube. I am interested in how you derived your numbers, though (1.4 times and 30%), as they seem plausible. 2:1 ratio of scanline to "empty" space seems about right.

I think a precise calculation on brightness would have to incorporate Pi to estimate the falloff at the edges of a typical raster. I'm not a mathematician though.


You're right- I should retract that statement altogether. Brightness is a very confusing topic to talk about, and that statement was based on a misunderstanding of the following post:

"From a purely photometric standpoint, each scanline of 240p (called "double strike" mode in purported Nintendo documents) probably emits exactly twice as much light power as each scanline of 480i. The reason it appears less than twice as bright is because as programmers, we're used to "twice as bright" meaning "twice as much voltage". But twice as much voltage produces roughly four times as much power, as power is the square of voltage for a given impedance. (It's not so simple in CRTs, as the gamma is slightly greater than 2.0 for various reasons.) Under this power-law assumption that perceived brightness is the square root of light power, the individual lines are as bright probably closer to 1.4 times as bright."

(https://forums.nesdev.com/viewtopic.php ... b&start=60)

"Perfect" scanlines are indeed 1:1, with each visible line having roughly twice the objective brightness. With perceived brightness being the square root of objective brightness, this results in each visible line being *perceived* as roughly 1.4 times as bright. The result is that 240p is the same brightness as 480i.

To emulate a perfect CRT without needing any confusing math:
1) Start with the calibrated brightness and backlight level and display a 100% white screen. Measure the light output (objective brightness) using a light meter.
2) Max out the backlight by setting brightness or backlight to 100%.
3) Apply scanlines, making the scanlines as close to 1:1 as possible (a 50% reduction in objective brightness per line)
4) Apply RGB aperture grille effect from "dotmask" shader
5) lower "mask dark" and increase "mask light" one step at a time until "mask dark" is as low as possible while maintaining the light output measured in step 1.
6) raising "mask light" will increase brightness and compensate for lowering "mask dark," but may result in clipping. Use a color bars test pattern to ensure that all bars are still visible after making adjustments to "mask dark" and "mask light." You'll have to repeat steps 5 and 6 until you find the ideal balance between contrast and mask strength that maintains light output.

Following this procedure, I've adjusted my shader settings to the following:

shader #0: image-adjustment
shader #0 filter: don't care
shader #0 scale: don't care

shader #1: zfast_CRT+dotmask
shader #1 filter: nearest
shader #1 scale: don't care

changes to parameter settings:

ia_monitor_gamma = “2.200000”

ia_target_gamma = “2.400000”

BLURSCALEX = “0.000000”

BRIGHTBOOST = “1.000000”

DOTMASK_STRENGTH = “0.300000”

feedback_pass = “0”

float_framebuffer0 = “false”

HILUMSCAN = “8.000000”

LOWLUMSCAN = “9.000000”

MASK_DARK = “0.000000”

MASK_FADE = “0.000000”

maskDark = “0.500000”

maskLight = “2.000000”

under “video options” bilinear filter is OFF, and integer scale is ON. Aspect ratio set to CUSTOM.

LCD backlight should be adjusted to 100% when using these settings. The following example should look good on any display that has a peak brightness of at least 350 cd/m2, since that's roughly the peak brightness of the display I'm using.

example:
Spoiler: show
Image


Last edited by Patrickbot on Sat Nov 10, 2018 10:59 pm, edited 2 times in total.

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 Post subject: Re: Emulation Shader recommendations
PostPosted: Sat Nov 10, 2018 10:40 pm 



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Posts: 12
fernan1234 wrote:
Yep you got it right. All zoomed-in like that it's pretty obvious because you can recognize each panel's pixel structure, but in person and from a normal viewing distance they are remarkably similar, especially the 5K monitor and the BVM. Of course once things start moving it's a whole different story. I'm optimistic about the future though.

You can probably make all those tweaks you would like by modifying settings in the shader file.

Someone also made an XM29-like shader, which may be closer to your preferences, but I haven't tested it so I can't speak to its quality.


Yeah, that 5K screen looks incredible. I'd like to see what it looks like with just 1:1 scanlines and aperture grille RGB mask, with the mask at maximum strength.

If you look at the image I posted just before this reply, that's pretty much what I consider "ideal" as far as CRT emulation goes, except I needed to compromise on the mask strength in order to have acceptable brightness. I think this image looks even better when resampled with some slight anti aliasing at the sub-pixel level. I was just noticing how good it looks on my iphone screen when I zoom in on the thumbnail; the individual phosphors actually appear to glow a bit.

I know this doesn't resemble any actual CRT, but it's what a hypothetically "perfect" 360 TVL CRT looks like.

Do you happen to know what that XM29 shader is called? I'd like to check that out. :)


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Sun Nov 11, 2018 1:38 am 



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Posts: 92
That does look pretty nice even if it does not look like any CRT I've seen. There's definitely a gain going from 4K to 5K with these shaders. Makes me wonder what they would look like on one of these 8K monitors!
https://www.bhphotovideo.com/c/product/ ... ultra.html

Probably would look like the sharpest CRT BVM that never was. 5K @ 27 inches is noticeably not as sharp as a D24, a 24 inch display may get closer, but I think an 8K one even at 31 inches may surpass it!

The XM29 shader was included in this Analog Shader Pack. I don't know if it's still being maintained though, but you can check out the thread here, they have a lot of other CRT shaders you may like: https://forums.libretro.com/t/analog-sh ... -here/5493


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Sun Nov 11, 2018 10:01 pm 



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Posts: 12
fernan1234 wrote:
That does look pretty nice even if it does not look like any CRT I've seen. There's definitely a gain going from 4K to 5K with these shaders. Makes me wonder what they would look like on one of these 8K monitors!
https://www.bhphotovideo.com/c/product/ ... ultra.html

Probably would look like the sharpest CRT BVM that never was. 5K @ 27 inches is noticeably not as sharp as a D24, a 24 inch display may get closer, but I think an 8K one even at 31 inches may surpass it!

The XM29 shader was included in this Analog Shader Pack. I don't know if it's still being maintained though, but you can check out the thread here, they have a lot of other CRT shaders you may like: https://forums.libretro.com/t/analog-sh ... -here/5493


Just for kicks, here's the max emulated TVL for each resolution. For a digital display, it's always (vertical resolution / 3 = emulated TVL)

1080p- 360 TVL.
1440p- 480 TVL
4K- 720 TVL
5K- 960 TVL
8K- 1440 TVL

So 1080p is similar to a 20" TV from the 80s or 90s; 1440p is similar to an "entry level" PVM; 4K is similar to a high-end PVM; 5K is similar to a BVM; and 8K is higher TVL than any CRT that ever existed, and would look the same as 1440p without the mask.

Looks like that 8K screen lacks HDR, which would definitely be a limiting factor for mask accuracy; just something to be wary of. HDR is a must-have for my next display.


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Mon Nov 12, 2018 3:47 am 



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Posts: 93
Patrickbot wrote:
So 1080p is similar to a 20" TV from the 80s or 90s; 1440p is similar to an "entry level" PVM; 4K is similar to a high-end PVM; 5K is similar to a BVM; and 8K is higher TVL than any CRT that ever existed, and would look the same as 1440p without the mask.

Looks like that 8K screen lacks HDR, which would definitely be a limiting factor for mask accuracy; just something to be wary of. HDR is a must-have for my next display.

We're arguably already there with the 2018+ LG OLED UHD TVs that have black frame insertion. 60 hz OLED w/ BFI is arguably getting into "good enough" territory for brightness over delta time to emulate the brightness pulse and decay of a CRT, though 120hz w/ BFI would be even better (2019+ LG OLEDs w/ 120 hz BFI and VRR via HDMI 2.1?). The current LG OLEDs will do a bit over 400 cd/m² continuously with a SDR signal, which should be enough for the color calibration standard of 120 cd/m² with double brightness needed for black frame insertion, then add another 30-50% for scanlines. A usable brightness of 150 cd/m² should be doable, which should be comparable to a CRT PC monitor, if memory serves. You also have the 2160p resolution to work with.

It's interesting to compare Journal of Vision's historical CRT vs OLED paper with Rting's 2018 LG C8 OLED review:
https://jov.arvojournals.org/article.as ... id=2194081
https://www.rtings.com/tv/reviews/lg/c8

If you want some more information straight from a former Sony engineer on PVM/BVM CRT variations/similarities, check our RetroRGB's interview with savon-pat:
https://www.youtube.com/watch?v=KVA35W9ICKQ


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Mon Nov 12, 2018 6:34 am 



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Posts: 111
So let's say now you found a grate shader (crt-royale-kurozumi) and now you want to pair it with a nice looking overlay. How to do that with out the shader geting crammed together.

https://forums.libretro.com/t/exodus-cr ... pport/9192
The overlays found here adds pixels to the top and bottom that you have to fit the game image into. But this makes the scanlines uneven and crate a kind of wave pattern.

Is there a way to fix this? The simple solution is to not use an overlay that adds anything except on the sides of the image.


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Tue Nov 13, 2018 7:43 pm 



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Posts: 12
energizerfellow‌ wrote:
Patrickbot wrote:
So 1080p is similar to a 20" TV from the 80s or 90s; 1440p is similar to an "entry level" PVM; 4K is similar to a high-end PVM; 5K is similar to a BVM; and 8K is higher TVL than any CRT that ever existed, and would look the same as 1440p without the mask.

Looks like that 8K screen lacks HDR, which would definitely be a limiting factor for mask accuracy; just something to be wary of. HDR is a must-have for my next display.

We're arguably already there with the 2018+ LG OLED UHD TVs that have black frame insertion. 60 hz OLED w/ BFI is arguably getting into "good enough" territory for brightness over delta time to emulate the brightness pulse and decay of a CRT, though 120hz w/ BFI would be even better (2019+ LG OLEDs w/ 120 hz BFI and VRR via HDMI 2.1?). The current LG OLEDs will do a bit over 400 cd/m² continuously with a SDR signal, which should be enough for the color calibration standard of 120 cd/m² with double brightness needed for black frame insertion, then add another 30-50% for scanlines. A usable brightness of 150 cd/m² should be doable, which should be comparable to a CRT PC monitor, if memory serves. You also have the 2160p resolution to work with.

It's interesting to compare Journal of Vision's historical CRT vs OLED paper with Rting's 2018 LG C8 OLED review:
https://jov.arvojournals.org/article.as ... id=2194081
https://www.rtings.com/tv/reviews/lg/c8

If you want some more information straight from a former Sony engineer on PVM/BVM CRT variations/similarities, check our RetroRGB's interview with savon-pat:
https://www.youtube.com/watch?v=KVA35W9ICKQ


thanks for the links- very interesting stuff, even if most of it flies right over my head! :D

Actually, I'm not sure 400 cd/m2 will cut it. My display (an ASUS VG248QE) reaches around 400 cd/m2 with the brightness and contrast maxed out, and it's still not bright enough to compensate for scanlines AND the RGB mask. IMO it's not enough to just have scanlines, you also need to emulate the phosphor structure/lower resolution (TVL) of a CRT, or else the image appears too sharp/smooth. The RGB mask (aperture grille) causes a HUGE amount of brightness to be lost, such that an HDR-capable display becomes necessary if you want an "accurate" RGB mask in addition to scanlines.


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Tue Nov 13, 2018 10:11 pm 


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@Fernan1234 - on the LG OLED TV and Retroarch.. how do I tell if the game is being run at 4K. I Flowed your instructions but I don't think that I am running the game in Mame at 4K. It looks like 720p b cause the game does not look sharp.. also is the supposed to run at 4K with HDR? Or just 4K? Thank for the feedback.

Vulkan changed on video and made the changed to 3 on the shader files.
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 Post subject: Re: Emulation Shader recommendations
PostPosted: Tue Nov 13, 2018 11:52 pm 



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Posts: 92
SNK-NEO-GEO wrote:
@Fernan1234 - on the LG OLED TV and Retroarch.. how do I tell if the game is being run at 4K. I Flowed your instructions but I don't think that I am running the game in Mame at 4K. It looks like 720p b cause the game does not look sharp.. also is the supposed to run at 4K with HDR? Or just 4K? Thank for the feedback.

Vulkan changed on video and made the changed to 3 on the shader files.



Retroarch should use the same resolution set for the OLED as an external display on Windows. Windows usually defaults to the best resolution of your display, so it should be doing 4K. Did you confirm its 3840 x 2160 on the Windows display settings? You should also check that it's doing 60Hz. If not, it could be that the cable going from your computer to the OLED. I've had problems using low quality mDP to HDMI cables, they passed 4K but only at 30Hz. If you're using HDMI to HDMI cables they may not have enough bandwidth?


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Wed Nov 14, 2018 2:08 am 


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@fernan1234 - that chader is the stuff "crt-royale-kurozumi.slangp".. I am running at 4k and enabled HDR on my OLED.. My take - the crt-royale-karozumi.slangp is the best settings on MAME that i have ever seen and I will use it moving forward. on the 55" OLED for me it will not work because, I need to be 7 feet away for things to look good and the resolution is not sharp enough, at 8k OLED 55" might be a different story or a 32' OLED @ 4 or 5k.

a few questions - RetroArch - is the MAME build core the latest or up to date to the regular MAME build?
Is there a way to use crt-royale-kurozumi.slangp with the up to date MAME or GroovyMAME? I want to use the shader with an up to date MAME on a PC CRT monitor, RetroArch looks very cool but when I scanned my MAME roms, it did not find all the games.... thanks
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 Post subject: Re: Emulation Shader recommendations
PostPosted: Wed Nov 14, 2018 2:49 am 



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SNK-NEO-GEO wrote:
I don't think that I am running the game in Mame at 4K. It looks like 720p b cause the game does not look sharp

By default MAME doesn't integer scale, but there were integer scaling options added to mainline MAME by Calamity from GroovyMAME back in 2016 for MAME 0.172. I'm partial to the unevenstretchx option that is integer scaled in the vertical and interpolated in the horizontal for correct aspect ratio and an acceptable CRT-like slight smoothing effect.

Search for "Calamity" in the changelogs for details:
https://www.mamedev.org/releases/whatsnew_0172.txt
https://www.mamedev.org/releases/whatsnew_0173.txt
https://www.mamedev.org/releases/whatsnew_0177.txt


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Wed Nov 14, 2018 5:03 am 



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SNK-NEO-GEO wrote:
@fernan1234 - that chader is the stuff "crt-royale-kurozumi.slangp".. I am running at 4k and enabled HDR on my OLED.. My take - the crt-royale-karozumi.slangp is the best settings on MAME that i have ever seen and I will use it moving forward. on the 55" OLED for me it will not work because, I need to be 7 feet away for things to look good and the resolution is not sharp enough, at 8k OLED 55" might be a different story or a 32' OLED @ 4 or 5k.

a few questions - RetroArch - is the MAME build core the latest or up to date to the regular MAME build?
Is there a way to use crt-royale-kurozumi.slangp with the up to date MAME or GroovyMAME? I want to use the shader with an up to date MAME on a PC CRT monitor, RetroArch looks very cool but when I scanned my MAME roms, it did not find all the games.... thanks


One more thing: Have you turned off bilinear filter on Retroarch? It's turned on by default for some strange reason. Turning it off makes 240p look nice and sharp.

Also I don't think HDR on the display side will make any difference since Retroarch doesn't have HDR output as far as I know.


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Wed Nov 14, 2018 9:32 am 



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SNK-NEO-GEO wrote:
@fernan1234 - that chader is the stuff "crt-royale-kurozumi.slangp".. I am running at 4k and enabled HDR on my OLED.. My take - the crt-royale-karozumi.slangp is the best settings on MAME that i have ever seen and I will use it moving forward. on the 55" OLED for me it will not work because, I need to be 7 feet away for things to look good and the resolution is not sharp enough, at 8k OLED 55" might be a different story or a 32' OLED @ 4 or 5k.

a few questions - RetroArch - is the MAME build core the latest or up to date to the regular MAME build?
Is there a way to use crt-royale-kurozumi.slangp with the up to date MAME or GroovyMAME? I want to use the shader with an up to date MAME on a PC CRT monitor, RetroArch looks very cool but when I scanned my MAME roms, it did not find all the games.... thanks


Regarding mame
https://www.libretro.com/index.php/intr ... -emulator/


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 Post subject: Re: Emulation Shader recommendations
PostPosted: Wed Nov 14, 2018 2:57 pm 


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@fernan1234 - thanks I will check on that.
@energizerfellow - thanks for the link
@Karmeck - I have to look into that.. I do see that MAME build with a label of test or something like that. I guess that we have to give it time.


back to one of my questions - Are you guys saying that "crt-royale-kurozumi.slangp" does not work on current MAME build because it MAME does not do integer scaling like the MAME build in RetroArch that can scale at 4k and such?

how about running current MAME on a PC CRT 31khz monitor? what is the best MAME build that can utilize "crt-royale-kurozumi.slangp" or equivalent? I have used MAME HLS but the scanline settings on the slider Menu just do not seem pleasing to my eyes and I think that something like royale shader is what I need, royale scanline effects really looks good.
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