The most accurate CRT experience possible - call to all shader pros

[MajorPainTheCactus]

I don’t think you can get a shadow mask or aperture grille mask etc to be bright enough on a standard dynamic range monitor. Which will be what someone with a MiSTer is using as HDR is flat out not supported.

If you think about it this makes sense as a mask is only going to darken the screen. At best it will keep it the same and as SDR monitors aren’t as bright as a CRT (my Sony PVM 2730 at least) then you aren’t going to get the brightness (or colours).

(Shameless plug) See my new shader which does everything in HDR for an example of getting the natural brightness of a CRT - you’ll need an LCD capable of 700 nits and more in my experience.

Also 4k is an absolute minimum I’d say for a 600TVL 4:3. As that’s number of lines across the screen to the height of the screen so a 600TVL will actually have 800 (600*(4/3)) lines across the whole width. Minimum pattern is 3 pixels really so that’s 3*800=2400 and the 3840 pixels of a 4k LCD is across a 16:9 screen i.e you have to take off a quarter of the pixels to get into 4:3 ratio i.e you have 2880 pixels to play with.

I squeeze a four pixel pattern into it and it seems to produce a close resolution.

Shaders: slang_shaders/HDR/CRT-sony-pvm-2730-4k-hdr.slangp

TVL description: https://andynumbers.wordpress.com/2016/07/21/lets-talk-about-tvl-count/

More info:

V1.0 Sony PVM HDR 4K Shader

Added slang-shaders\crt\crt-sony-pvm-4k-hdr.slangp (currently sitting in an open pull request) This shader is intended to build on my HDR support that I added RetroArch. The idea being that CRT’s are by far brighter than standard dynamic range LCD screens but maybe we can get much closer (and even surpass them) with high end HDR monitors that are now available. Indeed we can greatly simplify our shaders and get a more accurate CRT experience because we are now finally able to get effects like…

[MajorPainTheCactus]

Also you really need to take photos of the screen - not screenshots taken with a snipping tool or video grabber etc as that’s not going to let you see the natural bloom of a bright screen like a CRT or high end LCD. (Even photos are poor proxies to the real thing)

[Nesguy]

This is like zfast-crt level stuff, not much to get excited about IMO.

@MajorPainTheCactus

Some time ago I said that with 4K and HDR all we need is a very simple shader- just scanlines, mask, and some color grading. You’ve gone and proved it. Very nice work! Now I need to buy an HDR graphics card.

[MajorPainTheCactus]

Thanks @Nesguy! As always there’s lots we can improve upon especially more colour grading options, shadow and slot masks, geometry warping and introducing some of the ‘defects’ in CRT’s like misaligned convergence but we’ve got a good chunk of the way there given today’s display hardware limitations.

All we need now is for Linux/Vulkan to support HDR! I’d also like to see this in a lower powered device like a Raspberry Pi - the greatly simplified shaders make this much more possible. (Although 4K still seems out of the reach of the Pi 4 at the moment.)

[HyperspaceMadness]

@MajorPainTheCactus

All we need now is for Linux/Vulkan to support HDR!

Yeah, this is my dream ,

Thanks so much! I think this is a really amazing addition to retroarch and gift to the community.

I have an HDR monitor here, so I’m looking forward to try this out!

[MajorPainTheCactus]

So I was looking up HDR support in Vulkan and it does sound like it’s been added and that makes sense as Doom Eternal has HDR support. So possibly we’re good to go, just have to figure out how to use it.

[hunterk]

The best I can find on it documentation-wise is this: https://hackage.haskell.org/package/vulkan-3.14.1/docs/Vulkan-Extensions-VK_AMD_display_native_hdr.html

and this: https://www.khronos.org/registry/vulkan/specs/1.2-extensions/man/html/VkHdrMetadataEXT.html

For linux support, wayland appears to be “working on it” but that’s likely to take years: https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/14

RedHat has said they’re prioritizing it for 2022, and Valve wants it for Proton, but we’ll see how that goes.

There does seem to be a workaround for Vulkan’s KMS-like mode:

Linux lacks support for HDR10 at the level of the display server (be it X.org or Wayland). Since the display server does not support HDR10, neither does the window system or the desktop environment. Although it is possible to bypass this HDR10-incompatible software stack under specific circumstances (e.g. in fullscreen using the Direct Display Mode feature of the open-source AMDVLK Vulkan drivers with a compatible AMD GPU)

EDIT: looks like nvidia proposed an extension to xorg for DeepColor back in 2017 but I can’t find anything about it more recent than the proposal:

goins_hdr.pdf

[MajorPainTheCactus]

Thanks @hunterk!

Basically all we can do is implement HDR for Vulkan and then wait for HDR support be implemented and then wait for it to trickle down into the Linux version we’re using on the target device.

This could well be a couple of years wait even for something popular like the Raspberry Pi. Maybe Android will be a faster route?

[HyperspaceMadness]

@MajorPainTheCactus

Thanks @hunterk!

Basically all we can do is implement HDR for Vulkan and then wait for HDR support be implemented and then wait for it to trickle down into the Linux version we’re using on the target device.

Yeah thanks hunterk

Although Vulcan support would still be a great option in Windows as not all shaders play nice with D3d. And of course my enormous shader chain in the Mega Bezel is one of them

[MajorPainTheCactus]

Do we know what is broken with D3D in the shaders? I have noticed some of the larger shaders not working.

[HyperspaceMadness]

Not really, but I agree it seems to be more problematic on larger shaders. The problem with the Mega Bezel is an extreme one where when you load it in Vulcan or GLCore on Windows it maybe takes 10 seconds to load, but when you try to load it with D3D on Windows it is about 5 minutes or longer. I’m not sure what part of the process is lagging so much to cause this.

Here’s a link to the Mega Bezel if you haven’t seen it before:

https://forums.libretro.com/t/hsm-mega-bezel-reflection-shader-feedback-and-updates

[MajorPainTheCactus]

I have indeed seen your Mega Bezel thread - very impressive stuff indeed! Maybe I should try it on mine and use PIX to debug it but first I’m probably going to try adding HDR to Vulkan - looks relatively easy from what I’ve now seen of code snippets.

[HyperspaceMadness]

Very cool!, I haven’t used Pix before and only a bit of RenderDoc which would show me a lot of the info about the passes, buffers random data etc.

Good luck!

[Cyber]

Taking a look back, this looks great! Have you given up on this project or are all the learnings from this integrated in your newer project threads and in your GitHub projects?

[zerowing]

I was unsure where to post until I saw this topic. The topic can be endlessly debated but I wanted to post this

This is a 1960s Vacuum Tube General Electric Shadow Dot Mask CRT running on R from somebody on Reddit

r/crtgaming - That CRT television glow!

I’ve never seen Chrono Trigger look so smooth before Everytime somebody posts some trinitron or pvm with CT running on it you see the scanlines and an aliased picture far from the smooth picture from this 60s TV

I wonder if this 60s TV could be simulated with Shaders?

[Cyber]

@zerowing

I’ve never seen Chrono Trigger look so smooth before

@zerowing

far from the smooth picture from this 60s TV

@zerowing

I wonder if this 60s TV could be simulated with Shaders?

I’m seeing a lot of noise in the photo and it looks a little out of focus, not to mention the compression artifacts on top of that. Are you sure it’s the TV you would like to see recreated or the noisy, out of focus photo? it’s easy to add noise and probably some halation to almost any preset and get something starting to resemble that look.

Mega Bezel Reflection Shader! - Feedback and Updates

Has anyone seen or worked on something like Analog Shader Pack version 3\Televisions\Vintage\The Zenith\RF.cgp? I use this for a handful of 70s platforms and have never seen an equivalent. I’d like to move on to slang completely one day. [image]

Mega Bezel Reflection Shader! - Feedback and Updates

If you try my Composite - Sharp preset and turn on Curvature, increase the halation way up and probably the deconvergence noise and lastly, try some of the other mask types it might probably start to look something like that. After that you can probably try to reduce the first 2 Signal Resolution settings under GTU settings. If I have time I might try it myself. You can try these and tell me what you think: Updated: 19/10/21 CyberLab Mega Bezel Death To Pixels (70s RF) Series CyberLab Mega B…

[Duimon]

@zerowing

I wonder if this 60s TV could be simulated with Shaders?

If you are looking for a dot mask, some similar looks can be found playing with the Guest ADV base in the Mega Bezel.

Use these parameters pasted into a saved preset.

HSM_INTERLACE_TRIGGER_RES = "100.000000"
HSM_INTERLACE_MODE = "-1.000000"
m_glow = "1.000000"
glow = "1.059999"
shadowMask = "5.000000"
masksize = "0.000000"
mshift = "3.500000"
slotmask = "1.000000"
slotmask1 = "1.000000"
slotms = "0.000000"

Or save them to a *.params and use them as a local shader override in one of my presets.

I’m no expert, I’m sure others could come up with something better.

[zerowing]

@Cyber The noise you’re seeing is from RF input, not from image artifacts

The dude who posted the thread in reddit(LukeEvansSimon) also made the thread over at Shumps forum about modifying a CRT’s TVL.

You can see some of his comments in that reddit link I posted.

@Duimon I can still se the aliasing in your pic unlike that 60s TV

[Duimon]

I wasn’t even trying to come close, just showing that something like the dot mask was possible.

I’m positive that someone with more experience than me could replicate it with ease.

[hunterk]

how’s this? It’s just GTU with no scanlines, a drop in both vertical and horizontal res and a dotmask on top: