Awesome. I find it so ironic that the main thing tempting me to buy to a high resolution high framerate monitor is the desire to better emulate a low resolution low frame rate CRT.
After HD, adding pixels/framerate/depth/brightness is like a clean house: it's hard to articulate the value proposition up front in a way that does it justice and it's easy to talk yourself out of going to the trouble, but once you have it you realize just how good it is.
Just a mini-warning/FYI: running the 120hz test on my 60hz LCD IPad (Air 4) has caused that part of the screen with the crt effect to flicker even after leaving the demo. I don’t know what might cause this but it’s weird and worth a warning to anyone interested in trying this out.
(The flickering is more obvious when the control centre is opened, I managed to take a video of it but it’s only partially clear in it. It’s been about 5 minutes so far and I think the effect has reduced. I’m also quite perceptive to flickers so others might not notice it.)
This is a well known effect. LCD cells must be driven with alternating positive and negative values (of the same magnitude) to maintain an average neutral value, otherwise you get some kind of offset buildup that will result in flicker.
If you alternate every other image with a different color value, you upset that balance.
Thanks for explaining, I've run into this on my phone in other contexts and I was starting to think my phone screen is having its last days. Turns out it's expected? Usually I run into this when the screen brightness is at the lowest setting.
I have an AOC Q27G3XMN and while I do get reduced motion blur from this, I also experience very bad color banding/shifting. Messing with some of the values in the script config makes it slightly better, and changing the overdrive setting on the monitor seems to affect it as well, but there is still pretty strong banding no matter what strength it's on. I tested on my phone (Pixel 8) and it works very well there without any banding or color weirdness, so I guess it's just something about this particular monitor that doesn't work well with this method.
I’m a complete layperson on graphics and such, so please someone help me here: does this mean we’re now able to simulate old video game visuals on crt? That would be the best Christmas gift ever
Looks way more flickery than a real CRT at 120 Hz on an OLED phone. Maybe 240 Hz would be better.
Edit: I misunderstood and was running the 240 Hz version at 120 Hz. The 120 Hz version doesn't flicker noticeably. It does seem to reduce motion blur for 60 Hz content with a brightness penalty. It doesn't immediately make me feel like I'm looking at a CRT. Maybe it would if I had a 480 Hz monitor. There is a slight rolling banding artifact on my phone, maybe an artifact introduced by the display controller as described in the article.
The 120Hz shadertoy works on the Pixel 8 (and hopefully other 120Hz Android devices) if you go to Developer Options and enable "Force peak refresh rate"
I wonder if there's a way to ask Android Chrome to ask for 120Hz.
Ah, the non-developer option setting to enable 120Hz on later Pixels is under "Settings"->"Display & touch"->"Smooth display". With that enabled, Chrome will use 120Hz if power and temperature settings permit it to.
Ignoring the heavy flicker, it seems to reduce motion blur even with the 120 Hz demo running on a standard 60 Hz display. Especially visible on the windows. It doesn't seem like it should work, but it does?
But I find it hard to say that what it's supposed to look like. Motion blur is considered fine and correct in the "film look". Our eyes do crazy processing and can't really be emulated by a display technology without going to crazy lengths with high DPI, high dynamic range, high refresh rate (to emulate certain effects, not because we can properly see 90+ or so Hz) and probably eye tracking.
I think I like the slight (static) pixel blur of CRTs more than the motion-related behavior. The crazy DPI numbers of state of the art screens are seemingly not so much about showing detail than about hiding pixels. Calculating all of these pixels is, in a way, a waste of work. I'm talking about ~100 DPI, i.e. making a decent resolution look nicer, not about making low res crap look blurred instead of pixelated.
You need an 120hz display to run the 120hz demo.
I am surprised to see that the movement is clearer with the shader. You can follow the objects and they are more stable/more clear.
I appreciate the crazy high dpi very much. Because the text is super sharp, it helps with the focus. I am 48 and my eyes are not perfect. I look at screens for many hours every day and if the text is not sharp enough, I lose focus and everything becomes blurry. But super sharp and bright screens mean the eye can have a feedback loop for the correct focus distance.
This is better than BFI, although 120Hz demo on my screen looks like it's just alternating two or three parts of the image. Maybe there is a way to use fake interlacing to make it look convincing.
240Hz demo in 144Hz mode looks flickery but much more realistic.
I assume some people will approach this as stupidly as I did.
I wanted to see something and clicked on the 120Hz version not knowing what my laptop display actually is and while I am not photosensitive this was quite uncomfortable.
Thinking I don't understand what that is supposed to be I clicked on the 480Hz to see if that is better/different and that was even worse.
As a hail mary I clicked on the 240Hz and well that really made sense and was actually comfortable to look at.
So if you are like me and didn't really read through the text, this will only work for you if you select the Hz that matches your display ( which kinda is the whole point of why they are doing that ). If it looks bad you clicked the wrong link
I'm still interested in a "selective MPRT" GPU or monitor setting, that only does black frame insertion on changed parts of an image and a "safety margin" around them. This should reduce flicker on non-moving portions of an image/still screen while keeping moving portions sharper. But this probably isn't useful for office tasks, perhaps video, and high-framerate gaming (but only games running at a lower FPS than the screen can (partially?) redraw).
Tried on my simple 60Hz PC screen and also on my phone with OLED screen and sadly, it's just a flickering image. Will try later this week on my friends' retrogaming setup. Looks promising
I'm wondering if it would rather make more sense to emulate a CRT with a video projector and some shutter device (maybe a fan?) in front. Has anyone tried that yet?
To me this highlights that none of my hardware (pc, phone laptop) can actually render anything at native screen resolution and not occasionally drop frames.
Can we please design software to be frame-drop-free? Ie. if it drops a frame, even once, send a bug report to the developer to fix it, and if he cannot, refund me for the hardware?
My analogue TV from 1956 does not drop frames, I can assure you.
No. Light gun games rely on the fact that a CRT display will draw the picture on the screen pretty much at the same time it's generated by the console's video chip. Modern digital displays introduce all kinds of delays due to processing and buffering they do. Usually several frames worth. This shader can't do anything to fix that.
For the longest time, I thought this was the only limiting factor, but modern panels are low enough latency for it to work, yet still don’t.
The other important factor is the light filter. The NES Zapper has a filter designed to only be sensitive to high-frequency light sources like CRT screens.
That said, I bet you could fake the electron beam position with a high frame rate display, a modified version of this shader, and some kind of calibration routine…
You don't really need to emulate the position of the beam, at least not for the NES light gun. When you pull the trigger, the game first makes the entire screen black for one frame, reading the sensor in the gun and checking that it doesn't detect any light, and on the next frame, a white box is drawn where a duck would be. If the gun does detect light on this frame, it's counted as a hit. That second check is performed while the frame with the white box is still being drawn because CRT phosphors decay fairly quickly. You could, in theory, work around this with an LCD/OLED display with a high enough refresh rate that it would make up for the buffering delays.
FWIW I have the ASUS ROG Swift PG32UCDM 31.5" 4K UHD (3840 x 2160) 240Hz Gaming Monitor - a $1.3k monitor and also don't see anything different in the demo. Maybe I'm looking at the wrong thing. https://www.shadertoy.com/view/XfKfWd
This will let you know what your browser is allowing: https://www.testufo.com/framerates (it will also demonstrate the issue that the post is attempting to solve).
ios limits browser framerate by default, you can try going to settings > apps > safari > advanced > feature flags > disable "prefer page rendering near 60hz" and see if that has any effect. you can test by going to testufo and seeing if it gets the right framerate.
Awesome. I find it so ironic that the main thing tempting me to buy to a high resolution high framerate monitor is the desire to better emulate a low resolution low frame rate CRT.
After HD, adding pixels/framerate/depth/brightness is like a clean house: it's hard to articulate the value proposition up front in a way that does it justice and it's easy to talk yourself out of going to the trouble, but once you have it you realize just how good it is.
Just a mini-warning/FYI: running the 120hz test on my 60hz LCD IPad (Air 4) has caused that part of the screen with the crt effect to flicker even after leaving the demo. I don’t know what might cause this but it’s weird and worth a warning to anyone interested in trying this out.
(The flickering is more obvious when the control centre is opened, I managed to take a video of it but it’s only partially clear in it. It’s been about 5 minutes so far and I think the effect has reduced. I’m also quite perceptive to flickers so others might not notice it.)
This is a well known effect. LCD cells must be driven with alternating positive and negative values (of the same magnitude) to maintain an average neutral value, otherwise you get some kind of offset buildup that will result in flicker.
If you alternate every other image with a different color value, you upset that balance.
It will slowly rectify itself for most displays.
Thanks for explaining, I've run into this on my phone in other contexts and I was starting to think my phone screen is having its last days. Turns out it's expected? Usually I run into this when the screen brightness is at the lowest setting.
So Snow Crash[0] does affect both humans[1] and computers!
[0] https://en.wikipedia.org/wiki/Snow_Crash
[1] https://en.wikipedia.org/wiki/McCollough_effect
I have an AOC Q27G3XMN and while I do get reduced motion blur from this, I also experience very bad color banding/shifting. Messing with some of the values in the script config makes it slightly better, and changing the overdrive setting on the monitor seems to affect it as well, but there is still pretty strong banding no matter what strength it's on. I tested on my phone (Pixel 8) and it works very well there without any banding or color weirdness, so I guess it's just something about this particular monitor that doesn't work well with this method.
I’m a complete layperson on graphics and such, so please someone help me here: does this mean we’re now able to simulate old video game visuals on crt? That would be the best Christmas gift ever
We're getting closer, but 480Hz is still too slow for a convincing simulation of phosphor decay. 1000Hz will probably be enough.
Looks way more flickery than a real CRT at 120 Hz on an OLED phone. Maybe 240 Hz would be better.
Edit: I misunderstood and was running the 240 Hz version at 120 Hz. The 120 Hz version doesn't flicker noticeably. It does seem to reduce motion blur for 60 Hz content with a brightness penalty. It doesn't immediately make me feel like I'm looking at a CRT. Maybe it would if I had a 480 Hz monitor. There is a slight rolling banding artifact on my phone, maybe an artifact introduced by the display controller as described in the article.
Nice! Does-this/can-this handle interlacing?
https://en.m.wikipedia.org/wiki/Interlaced_video
(Half vertical resolution, offset a bit every other frame)
The 120Hz shadertoy works on the Pixel 8 (and hopefully other 120Hz Android devices) if you go to Developer Options and enable "Force peak refresh rate"
I wonder if there's a way to ask Android Chrome to ask for 120Hz.
Ah, the non-developer option setting to enable 120Hz on later Pixels is under "Settings"->"Display & touch"->"Smooth display". With that enabled, Chrome will use 120Hz if power and temperature settings permit it to.
Thanks for the hint, I had this setting enabled, but it didn't look good on Firefox, but using chrome made it look good!
Ignoring the heavy flicker, it seems to reduce motion blur even with the 120 Hz demo running on a standard 60 Hz display. Especially visible on the windows. It doesn't seem like it should work, but it does?
But I find it hard to say that what it's supposed to look like. Motion blur is considered fine and correct in the "film look". Our eyes do crazy processing and can't really be emulated by a display technology without going to crazy lengths with high DPI, high dynamic range, high refresh rate (to emulate certain effects, not because we can properly see 90+ or so Hz) and probably eye tracking.
I think I like the slight (static) pixel blur of CRTs more than the motion-related behavior. The crazy DPI numbers of state of the art screens are seemingly not so much about showing detail than about hiding pixels. Calculating all of these pixels is, in a way, a waste of work. I'm talking about ~100 DPI, i.e. making a decent resolution look nicer, not about making low res crap look blurred instead of pixelated.
You need an 120hz display to run the 120hz demo. I am surprised to see that the movement is clearer with the shader. You can follow the objects and they are more stable/more clear.
I appreciate the crazy high dpi very much. Because the text is super sharp, it helps with the focus. I am 48 and my eyes are not perfect. I look at screens for many hours every day and if the text is not sharp enough, I lose focus and everything becomes blurry. But super sharp and bright screens mean the eye can have a feedback loop for the correct focus distance.
This looks REALLY good on a 240hz monitor. Much better than BFI (which I don't use because it's pretty bad on my monitor)
This is better than BFI, although 120Hz demo on my screen looks like it's just alternating two or three parts of the image. Maybe there is a way to use fake interlacing to make it look convincing.
240Hz demo in 144Hz mode looks flickery but much more realistic.
I've thought for a while that we need to simulate how phosphorus face in and out, at the very least.
I assume some people will approach this as stupidly as I did.
I wanted to see something and clicked on the 120Hz version not knowing what my laptop display actually is and while I am not photosensitive this was quite uncomfortable. Thinking I don't understand what that is supposed to be I clicked on the 480Hz to see if that is better/different and that was even worse. As a hail mary I clicked on the 240Hz and well that really made sense and was actually comfortable to look at.
So if you are like me and didn't really read through the text, this will only work for you if you select the Hz that matches your display ( which kinda is the whole point of why they are doing that ). If it looks bad you clicked the wrong link
I'm still interested in a "selective MPRT" GPU or monitor setting, that only does black frame insertion on changed parts of an image and a "safety margin" around them. This should reduce flicker on non-moving portions of an image/still screen while keeping moving portions sharper. But this probably isn't useful for office tasks, perhaps video, and high-framerate gaming (but only games running at a lower FPS than the screen can (partially?) redraw).
Tried on my simple 60Hz PC screen and also on my phone with OLED screen and sadly, it's just a flickering image. Will try later this week on my friends' retrogaming setup. Looks promising
I'm wondering if it would rather make more sense to emulate a CRT with a video projector and some shutter device (maybe a fan?) in front. Has anyone tried that yet?
This probably goes without saying but...
If you have photosensitive migraine or epilepsy, stay the hell away from those demos.
To me this highlights that none of my hardware (pc, phone laptop) can actually render anything at native screen resolution and not occasionally drop frames.
Can we please design software to be frame-drop-free? Ie. if it drops a frame, even once, send a bug report to the developer to fix it, and if he cannot, refund me for the hardware?
My analogue TV from 1956 does not drop frames, I can assure you.
Can I use this to play Duck Hunt?
No. Light gun games rely on the fact that a CRT display will draw the picture on the screen pretty much at the same time it's generated by the console's video chip. Modern digital displays introduce all kinds of delays due to processing and buffering they do. Usually several frames worth. This shader can't do anything to fix that.
For the longest time, I thought this was the only limiting factor, but modern panels are low enough latency for it to work, yet still don’t.
The other important factor is the light filter. The NES Zapper has a filter designed to only be sensitive to high-frequency light sources like CRT screens.
https://www.nesdev.org/wiki/Zapper#Light_Sensor
That said, I bet you could fake the electron beam position with a high frame rate display, a modified version of this shader, and some kind of calibration routine…
You don't really need to emulate the position of the beam, at least not for the NES light gun. When you pull the trigger, the game first makes the entire screen black for one frame, reading the sensor in the gun and checking that it doesn't detect any light, and on the next frame, a white box is drawn where a duck would be. If the gun does detect light on this frame, it's counted as a hit. That second check is performed while the frame with the white box is still being drawn because CRT phosphors decay fairly quickly. You could, in theory, work around this with an LCD/OLED display with a high enough refresh rate that it would make up for the buffering delays.
You wouldn't be able to get horizontal position.
I tried the 120Hz demo but can't really tell there's any effect. Does it look cooler with 240Hz?
FWIW I have the ASUS ROG Swift PG32UCDM 31.5" 4K UHD (3840 x 2160) 240Hz Gaming Monitor - a $1.3k monitor and also don't see anything different in the demo. Maybe I'm looking at the wrong thing. https://www.shadertoy.com/view/XfKfWd
Make sure your browser lets you refresh at those framerates.
Safari by default caps animations other than scrolling at 60fps (I think?).
This will let you know what your browser is allowing: https://www.testufo.com/framerates (it will also demonstrate the issue that the post is attempting to solve).
I only get an hyphen on the iPhone
I got 60fps/60Hz on mine (iPhone 16 Pro, iOS 18.2).
Just FYI, you can go to Settings -> Safari -> Advanced -> Feature Flags -> Prefer Page Rendering Updates near 60fps and switch it off to get 120Hz
I just see a flickering image. What am I missing on iPhone?
ios limits browser framerate by default, you can try going to settings > apps > safari > advanced > feature flags > disable "prefer page rendering near 60hz" and see if that has any effect. you can test by going to testufo and seeing if it gets the right framerate.