CRT-Yah! A new shader chain

[Squalo]

@colourofsound

Thanks, I’ll give that a try! Do you have a real set to compare Yah against? It’s far and away becoming my favourite, it’s so easy to get good results.

My crts are currently in storage, the poor things. I just don’t need them anymore. This is why

Regarding halation, adding it yourself is basically going to create a preset that is pretty much yah multipass minus ntsc. This is where halation comes from

shader5 = "shaders/crt-yah/blur-horizontal.slang"
filter_linear5 = true // required: sample lut-output linear

shader6 = "shaders/crt-yah/blur-vertical.slang"
filter_linear6 = true

It’s the same tried and true method that other shaders use, afaik. If your device is really struggling with the blur passes, try prepending Hyllian’s dilation (in the “warp” folder). It’s not the same but it might be faster.

You can also run the shader at lower resolutions, makes a big difference with older machines and still looks great. Try 1920x1080 (easy way out) and if that’s still a bit slow, 1280x960 and 1194x896 are nice 4:3 integer vertical multiples of 240 and 224 respectively.

[colourofsound]

What are the chances of a Reshade version of Yah? If I had any idea how to code I’d try it myself!

[Jezze]

A new version is on the way addressing some of your feedback.

NTSC changes:

• Renamed “Quality” parameter to “Chroma Phase” (“Field Merge” has been removed, see new “Jitter” parameter)
• Added new “Chroma Shift” parameter, which enables the rainbow effect
  @ynnad4: use “Two-Phase” and set “Chroma Shift” to -1 or 1
• Reduced blurriness by disabling the bi-linear texture filtering of the upscale pass. If you have created your own complex preset, you have to set filter_linear for ntsc-pass1 to false manually.
  @colourofsound: in addition you can set the “Beam Filter” parameter into the “Blocky” direction (e.g. -0.75) to get a sharper NTSC appearance
• Added a new “Jitter” parameter, which let you disable the jitter effect. The old “Field Merge” setting of Three-Phase basically did that before, now you can do the same for Two-Phase as well.

Preset (crt/shaders/crt-yah/presets) changes:

• Reduced Deconverge, Phosphor and Halation effect across all presets slightly
• Adjusted Contrast and Brightness across all presets to be less dark
• Added pure-NTSC preset
• Added pure-Scanlines preset based on @Squalo’s configuration (not exactly the same, though)

Other changes:

• Added new “Screen Frequency” parameter to select between 30 and 60 Hz affecting the speed of the NTSC and Scanline Jitter effects.

@colourofsound
Regarding a Reshade version of CRT-Yah, I have not looked into it yet. The chances of porting it myself depend on how much of the code I have to rewrite.

[colourofsound]

Epic work! Very excited about a potential Reshade port

NTSC is still a bit blurry for me it has to be said; but I’m not too bothered about using that setting.

Would you mind explaining the sub pixel settings? On my LG OLED setting 2 looks pretty good and it’d be good to understand why

[Jezze]

Not sure what else I could do to further reduce the blurriness of the NTSC effect. The recent changes should have eliminated the blurriness in the vertical (y) direction. But as for the horizontal (x) direction, I’d say that’s just the nature of the effect, esp. for the two-phase option.

Regarding the sub-pixel mask setting: 2-MG stands for magenta/green. So the sub-pixel mask consists of only two alternating colors instead of three as with RGB. This is actually nothing special; other shaders also offer this type of sub-pixel mask. Magenta/green usually appears more uniform, because the brightness between magenta and green is very similar, unlike the brightness between RGB.

However, a special feature of this shader compared to most others is the scaling of the sub-pixel mask based on the screen resolution. For example, at 1080p, the sub-pixel size is 1, while at 2160p (4K), the sub-pixel size is automatically scaled to 2.

Long story short, I don’t know why magenta/green works better for your LG OLED. The interaction of the actual sup-pixel grid of your display and the simulated sub-pixel mask can be quite complex and also can lead to artifacts, esp. with a sub-pixel size of 1.

[Cyber]

@Jezze

Long story short, I don’t know why magenta/green works better for your LG OLED. The interaction of the actual sup-pixel grid of your display and the simulated sub-pixel mask can be quite complex and also can lead to artifacts, esp. with a sub-pixel size of 1.

I was hoping this would be common knowledge by now but LG 4K OLED TVs before the G5 use RWBG subpixel layout, therefore the only CRT Shader Subpixel Mask that would align properly and evenly is RRBBGGX (and possibly XRRBBGG but I haven’t tested that on any OLED TV). Regular RGB or BGR Subpixel Masks would not look accurate at least close up to the screen because of this.

OLED subpixels. How do they work?

Here are some macro shots of Wii Sports running on an LG 55OLEDE6P using CyberLab Mega Bezel Death To Pixels Shader Preset Pack. The first ones are using CyberLab Wii, which uses Mask 6 at size 2, while the others use Mask 7 and 8 at different sizes. The last set uses Mask 6 size 2 with aperture grille layout followed by Mask 7 and 8 at various sizes. This could be the final verdict on the accuracy and capability of WOLED TVs to depict RGB phosphor triad emulation properly. So far it doesn’t…

[passballtotucker]

This shader looks really good. Is there a way to turn off the flickering though?

[Jezze]

You can turn off the scanlines jitter and also the jitter of the NTSC effect when activated:

• set “Scanlines > Offset” to 0
• set “NTSC > Jitter” to 0

There is also some animated noise you can disable:

• set “CRT > Noise” to 0

[Dante]

Hi, great shader for starters! Actually it’s now by default shader I really like it. I have a question though. For 480p content what settings should I set in order to have a more convincing look?

[passballtotucker]

Alt+Tabing and going back in gets rid of the flicker without adjusting any of those settings. Not sure what the issue is. Sorry, this is happening on other shaders too.

[Buccaneer]

FYI : With the newest version i had to turn down saturation from 1.15 to 0.95 otherwhise I got black fragments in bright Letters on different cores and systems across the board. As soon as I went under1.00 they were gone

[Jezze]

@Dante Depends on what you mean by convincing. Since you mention 480p, e.g. like Dreamcast or Naomi: This resolution is automatically down-scaled to 240p. You can return to 480p by setting the “Screen > Scale” to 1, or you try 360p by setting the value to 0.5.

@passballtotucker What video driver do you use? I usually go with Vulcan and rarely test the others.

@Buccaneer The shader code for saturation was actually not changed only the preset settings. Were you able to configure a saturation above 1.0 before? And what video driver do you use? I will test other than Vulcan, and try to reproduce this issue.

[Jezze]

I could not reproduce the issue with other video drivers. However, the saturation method I use could produce numeric errors, leading to NaN or Inf, which could be handled differently from hardware to hardware.

There might be a simple solution, which should prevent the potential numeric errors. Can you open the file crt\shaders\crt-yah\common\color-helper.h go to line 82 and replace:

    return saturation > 1.0
        // increase
        ? apply_scale(pow(color, vec3(saturation)), max_color(color))
        // decrease
        : mix(vec3(luminance), color, saturation);

by:

    return mix(vec3(luminance), color, saturation);

This does not give the exact same result as before, but is very close.

If that works for you, I will provide an updated version soon.

[Buccaneer]

Tested and I can confirm with that code it works flawlessly with saturation above 1.0. PS I use vulkan and the saturation was above 1.0 since a long time…sttrangely with the latest version the problem came up. Thx

[Cyber]

Hey great shader. I wish there was a way to control the NTSC Resolution or Resolution Scale because when I enabled NTSC things got way too blurry without any ability to fine tune it.

I tried loading my Blargg NTSC Video Filter presets but I got a black screen when attempting to load using Beetle PCE/SGX/CD. Apparently the NTSC Video Filter preset loading isn’t broken when using Beetle PCE Fast. This last part is for @hunterk, @Tatsuya79, and @barbudreadmon.

@Jezze On another note, besides the lack of WOLED specific subpixel mask layouts mentioned above, I sorely missed subpixel mask layouts for bgr displays, which is what I’m currently using for the most part but great work on a shader that makes it easy to keep things bright while remaining saturated and providing full opacity mask and scanline emulation and more!

[Jezze]

Another update is coming soon and address some of the recently discussed topics.

• fixed potential numeric errors of the “Color > Saturation” parameter, by changing the way its applied. This slightly increased the saturation intensity; presets have been adjusted accordingly
• added “NTSC > Scale” parameter, which is independent from the existing “Screen > Scale” parameter and can be used to sharpen the NTSC effect, but depending on the amount you will loose the semi-transparency effect of it
• reduced the black gap between sub-pixel blocks:
  Previously, the subpixel type “5-RGBK” (now labeled “5-RGB/x”) resulted in RRGGBBXX when scaled by a factor of 2 (default for 4K). Now the black component (XX) has been halved to RRGGBBX

@Cyber
I have not added a BGR or RBG option (yet) because I cannot see any difference in the order of the colors, at least not from a distance of 3 meters in front of the TV. I understand the desire to align the simulated subpixel mask with the display’s native subpixel grid. However, in my opinion, this will never work because the native subpixel grid is at least three times smaller than the simulated subpixel mask. A single simulated R, G, B always covers at least one entire native RGB.

[colourofsound]

Earthion + Yah is just….lovely

[Jezze]

A new version (#850, #851) will be available soon and brings some minor tweaks.

• corrected an half pixel shift when the image is down-scaled automatically

  This shift was only noticeable when a game changed resolutions, like some SNES games switching from 224p to 448p when displaying a high-res font.

• changed “Mask Size” parameter to “Mask Scale” to make the (manual) mask sizing/scaling independent from the output resolution

  Previously the “Mask Size” parameter incremented the base size by 1px, which let to different results with different output resolutions: 1080p vs. 2160p. The “Mask Scale” parameter increments the base size by a multiple

• added “Sub-Pixel Shape” parameter to control the smoothness of individual sub-pixel

  This setting is only noticeable for sub-pixel with a size of least 3px; for 4K displays and beyond

• adjusted “Brightness Compensation” to include “Sub-Pixel Shape” and “Mask Bleed” parameters
• added curved CRT+NTSC preset (crt/shaders/crt-yah/presets/pure-crt)
• added color LCD preset (crt/shaders/crt-yah/presets/pure-lcd)

  Although the shader is primarily intended to imitate CRT effects, I have added a preset to simulate LCD screens such as the GBA.

[ynnad4]

Hey bud, have been out for a while.

This looks very excellent now (from my taste). Thank you for incorporating it.

Its cool old school looking exp. from the real good.

The blurriness will always bring authentic feeling to be made from 90s.

Thank you for the really cool preset around. It will surely bring tons of fun, thanks to you .

[PU786]

Are we going to get an option for Double Scanlines/480p mode? It would be very helpful for things like the Dreamcast or the PSX bios, or Panzer Dragoon Zwei…or an HD CRT shader preset.