5 ms·

High-DPI OLEDs and CRT shaders are the answer for preservation, I think. Shaders can cover a hell of a lot of the nuance. Phosphor persistence (fade-out time?),

High-DPI OLEDs and CRT shaders are the answer for preservation, I think. Shaders can cover a hell of a lot of the nuance. Phosphor persistence (fade-out time?), light bleeding over into the next uh... thingie. We have the technology :) the shaders may not be perfect yet, but it makes me happy that we have the option.

zozbot234 3y ago
High-DPI OLED can do even better than the analog effect of CRT's. The latter is basically like a Gaussian blur (which is the best you can do in the purely analog domain!) but a high-DPI screen can use Lanczos upscaling for a much sharper effect, somewhat reminiscent of the look of oil or water-color paintings. There are also pixel-art specific upscaling algorithms that preserve the limited color palette of old retrogames while still smoothing out lines and curves.
- PostOnce 3y ago
  I lose it when I go to an arcade and they have some bootleg emulator running with one of those hideous blurry upscaling filters turned on. It's like George Lucas and his Original Vision problem... it's not good to mess with existing art people already love
- thfuran 3y ago
  >water-color paintings That's not really a medium known for its sharp edges and fine details.
  - zozbot234 3y ago
    Yes, the point is that given any level of detail the water-color picture is a lot sharper than the Gaussian-blur equivalent, which is like putting a pane of frosted glass over the picture.
  - ralferoo 3y ago
    Maybe not, but if you were to compare a low-resolution scan and a high-resolution scan of the painting, you'd easily see the difference.
  - watercolorblind 3y ago
    Yeah, it's a medium that is not known for fine details given everyone's experience with it in school growing up, and the landscape/flower paintings that are common at art festivals; however, that does not mean that is all that can be done with the medium. Some artists pursue photo-realism [1]. Using something like a heavier weight (takes more layers), hot press (smoother grain) watercolor that makes it easier to add finer sharper, details. Additionally, there are mixing mediums [2] that allow changing application in different ways and there is masking fluid which helps preserve a sharp edge when working on multiple layers. There is a variety of media that is "watercolor" as well: watercolor pencils, water soluble pastels, opaque watercolors, watercolor markers, and granulating watercolors. 1: https://doodlewash.com/guest-artist-photorealism-watercolors-meeta-dani/ https://doodlewash.com/guest-artist-photorealism-watercolors... 2: https://www.art-is-fun.com/watercolor-mediums https://www.art-is-fun.com/watercolor-mediums
    - lttlrck 3y ago
      Wow, those watercolors are astonishing.
- dcow 3y ago
  I have a 120hz OLED. Where can I check this out?
- rob74 3y ago
  I'm afraid you're missing the point here - people don't want "even better" than CRTs (otherwise they might as well go and play the latest 3D shooter on their 4K display), they want something which gets as close as possible to how a real CRT looked like.
  - Yeul 3y ago
    I wonder if these people watch Blade Runner on videocassette or if they opt for the blueray release.
    - ralferoo 3y ago
      Blade Runner was intended to be seen on 70mm film in a cinema. People who saw it at a 35mm-only cinema (the vast majority) would have experienced a slightly inferior picture quality. The 4K scan of the film may or may not match the quality of the original film depending on the graininess of the film, but from a 70mm source it will probably be slightly inferior to the film version, however grainy 35mm prints have grains bigger than a 4K pixel, so the transfer is about the same quality. Someone watching the film on a VCR (or even a DVD) isn't getting anywhere close to the original intended experience. They may still get a lot of the atmosphere from the experience, but it was always a sub-par experience compared to the cinema, and most people who who watched films on a VCR were only too well aware of that as even most commercial VCR tapes weren't up to the standard that was possible for broadcast OTA TV especially for PAL. In contrast, running a video game designed for NTSC or PAL TV's, usually somwhere between 320 and ~350 horizontal pixels that were then encoded to NTSC or PAL, so keeping the original pixel accuracy on the luma component of the colour, but smudging colours to a lower accuracy in the chroma (each line was ~280 colour clocks, but some of these weren't visible, so maybe estimate 200 pixels horizontally), and finally output to a TV with a different arrangement of pixels again depending on the mask in the TV. It was pretty much accepted that single pixels wouldn't be the colour they were supposed to be, and many pixel games used dithering to create new colours and colour gradients to make up for limited palettes from the hardware and usually even more limited palettes from the colour look-up tables (because memory was a premium, systems were often 4 colours from a choice of 16 or similar). Even well before the advent of LCD TVs, some games looked a bit ugly when using a higher quality RGB computer monitor (e.g. the 1080 for the Amiga) compared to using a TV, even though the monitor was vastly superior for applications. To compensate for the relatively low refresh rate of interlaced broadcast TV, the phosphor on the screen was designed to decay in brightness slowly so that the alternate lines would fill in the gaps left from the previous field to give the impression of a higher vertical resolution (this is why NTSC is usually called 480i30 and PAL 576i25) but in practice, most games treated each field individually and depending on the timing of the signal they output, it might not even be actually interlaced at all, so games really ran at 240p60 (NTSC) or 288p50 (PAL) with some blur between frames from the phosphor which wasn't designed for that. As an aside, this is why live TV broadcasts (i.e. using an old TV camera rather than a film scan) look so jaggy on a modern TV - although they are interlaced, the two fields aren't independent when the camera or subjects are moving as the image is captured twice in different positions. This looks OK on a TV, because the phosphor has decayed a bit and the newer image is slightly brighter, but also because the image is effectively blurred across a couple of frames anyway. Later studio cameras in the digital age captured the whole image at once and output a genuine interlaced signal where the odd and even frames were coherent. When you try to play a game designed for CRT on a modern LCD TV, first of all, you don't get any of the effects mentioned above, you just get a crisp square that fills the entire pixel space. Some TVs allow a "clarity" or "crispness" adjustment that blurs the image a bit, but fundamentally the image is never what was intended originally, nor how it was perceived when seen on a CRT. Attempts to up-scale these low-resolution images to take advantage of the higher-resolution from the LCD can often lead to even weirder artifacts - e.g. you might like an upscaler to recognise a diagonal edge and create a smooth diagonal, but this can lead to weird diamond patterns in dithered areas. And some TVs might also try to de-interlace the image, leading to the jaggies I mentioned above from live TV cameras. All in all, games from a certain era were designed to look good on the output technology of the time, and modern TVs generally do a terrible job of replicating that experience unless you go through a specialised CRT filter which tries to replicate in software the effect you'd get if you stuck a hi-resolution digital camera in front of an old CRT displaying the signal. Some of these are actually pretty good, but vastly different from what you'd get plugging your old game directly into a TV. Films were generally designed for watching in the cinema, and were broadcast on TV at a lower quality, and sold on VCR at an even worse quality. Watching a high quality transfer on a blu-ray is much closer to how they were intended to be seen, and not only doesn't create any weird artifacts by being better quality than you'd have seen on your CRT showing a VCR tape, it'll actually reveal new details that were always there in the film that were just missing on the VCR version.
MenhirMike 3y ago
The nice thing about High DPI is that you can re-create the aperture grille/shadow mask of a real TV to get the actual sub-pixel pattern. That requires a high resolution since you need both enough pixels (since every original "pixel" requires 4+ pixels now) and small enough pixels (to make the effect not overly exaggerated - unless you want to emulate a low end TV with gigantic dot pitch). Also, no more "fake" scanlines because the entire mask is fake :) Also, issues with pixel aspect ratio (8:7 vs 5:4 vs 4:3, square vs rectangular pixels) can be resolved while still being able to scale by exact integers rather than floats. It's funny, but 4K displays might really be one of the best ways to play retro games nowadays, I'm hoping that upscalers (like the Retrotink 4K, or maybe future OSSC upgrades) will bring some of the stuff we've been doing in emulators to real hardware as well (though yes, that thing will cost several hundreds of dollars, so emulation is probably going to stay the preferred option for many). Now we just have to solve losing the sync signal for games that switch between 240p and 480i during gameplay, or that don't have an exact 60 Hz refresh rate - Variable Refresh Rate displays are actually a real opportunity here as well. Oh, and find a way to all of that without introducing any display processing latency.
- rob74 3y ago
  So it takes a 14" 4:3 4k resolution OLED display (does such a thing even exist?) and a top-of-the-line GPU to emulate a 30+ year old 14" CRT monitor?
  - MenhirMike 3y ago
    And even then it's probably still not perfect since you're sending to a framebuffer instead of controlling the beam directly, which adds at minimum 1 frame of latency. (Unless there is a "real-time" way to send a picture over HDMI)
    - nyanpasu64 3y ago
      Super Mario World and many other SNES (and later) games spends two frames after a controller jump input sending unchanged frames on-screen, before showing a frame where the player is jumping (tested in slow-motion camera). Emulators (and possibly FPGAs) can use run-ahead to skip past one or more of these "no change" frames, reducing input latency to match or surpass console latency (https://github.com/higan-emu/emulation-articles/tree/master/input/run-ahead https://github.com/higan-emu/emulation-articles/tree/master/...). Another strategy is to delay polling input computing the next frame until the end of the previous frame being drawn (RetroArch frame delay). This does not rely on the game not responding immediately to controller input, but is more prone to dropping frames if your CPU gets occupied and can't run your emulator for a few milliseconds. It is possible to compute and display images in near-real-time over HDMI, but this technique is quite niche (https://blurbusters.com/blur-busters-lagless-raster-follower-algorithm-for-emulator-developers/ https://blurbusters.com/blur-busters-lagless-raster-follower...).
WithinReason 3y ago
In addition, high DPI/refresh screens can recreate any CRT you have a shader for, or only recreate the "artistically relevant" aspect, the blur and gamma characteristics and not recreate the irrelevant flaws of CRTs.
bluescrn 3y ago
High DPI screens give more options for exact integer scaling too, before putting shaders over the top. The other often-forgotten issue is running 50Hz PAL games smoothly. This should be getting easier, with more screens able to run at 100Hz, but it's rare to see an emulator actually support this. Would be nice if modern 4:3 panels were available, too (And not just for retro gaming, they were more practical than 16:9 for work PCs)
willis936 3y ago
I think we are still several years away from flat panels being able to sinulate phosphor persistence and the strobed nature of CRTs. CRT phosphors decay with a time constant of 1-2 ms, so you'd want at least 1000 Hz to properly simulate it. Even if you couldn't get that fast you could at least get the meat of it with backlight strobing that has ~25% duty cycle. This gives incredible motion clarity but it is very rare on modern displays. I don't really know why. Display manufacturers should be giving users the option to reduce brightness by 75% for motion clarity if they want it. It will also be a while yet before modern displays can hit the product of motion clarity and brightness that CRTs have hit since before we were born.
- zozbot234 3y ago
  > with backlight strobing that has ~25% duty cycle. Yes, that's what happens when you set screen brightness to the lowest setting. And guess what, it looks terrible.
  - willis936 3y ago
    Similar, but not exactly. The details matter. The strobing needs to be synchronous with the frames. Adding flicker without the motion clarity benefit looks bad. Strobing in sync with content looks amazing. How many people complained about 60 Hz flicker on CRTs over their 70 year reign? https://forums.blurbusters.com/viewtopic.php?t=6519 https://forums.blurbusters.com/viewtopic.php?t=6519

zozbot234 3y ago

High-DPI OLED can do even better than the analog effect of CRT's. The latter is basically like a Gaussian blur (which is the best you can do in the purely analog domain!) but a high-DPI screen can use Lanczos upscaling for a much sharper effect, somewhat reminiscent of the look of oil or water-color paintings. There are also pixel-art specific upscaling algorithms that preserve the limited color palette of old retrogames while still smoothing out lines and curves.

PostOnce 3y ago
I lose it when I go to an arcade and they have some bootleg emulator running with one of those hideous blurry upscaling filters turned on. It's like George Lucas and his Original Vision problem... it's not good to mess with existing art people already love
thfuran 3y ago
>water-color paintings That's not really a medium known for its sharp edges and fine details.
- zozbot234 3y ago
  Yes, the point is that given any level of detail the water-color picture is a lot sharper than the Gaussian-blur equivalent, which is like putting a pane of frosted glass over the picture.
- ralferoo 3y ago
  Maybe not, but if you were to compare a low-resolution scan and a high-resolution scan of the painting, you'd easily see the difference.
- watercolorblind 3y ago
  Yeah, it's a medium that is not known for fine details given everyone's experience with it in school growing up, and the landscape/flower paintings that are common at art festivals; however, that does not mean that is all that can be done with the medium. Some artists pursue photo-realism [1]. Using something like a heavier weight (takes more layers), hot press (smoother grain) watercolor that makes it easier to add finer sharper, details. Additionally, there are mixing mediums [2] that allow changing application in different ways and there is masking fluid which helps preserve a sharp edge when working on multiple layers. There is a variety of media that is "watercolor" as well: watercolor pencils, water soluble pastels, opaque watercolors, watercolor markers, and granulating watercolors. 1: https://doodlewash.com/guest-artist-photorealism-watercolors-meeta-dani/ https://doodlewash.com/guest-artist-photorealism-watercolors... 2: https://www.art-is-fun.com/watercolor-mediums https://www.art-is-fun.com/watercolor-mediums
  - lttlrck 3y ago
    Wow, those watercolors are astonishing.
dcow 3y ago
I have a 120hz OLED. Where can I check this out?
rob74 3y ago
I'm afraid you're missing the point here - people don't want "even better" than CRTs (otherwise they might as well go and play the latest 3D shooter on their 4K display), they want something which gets as close as possible to how a real CRT looked like.
- Yeul 3y ago
  I wonder if these people watch Blade Runner on videocassette or if they opt for the blueray release.
  - ralferoo 3y ago
    Blade Runner was intended to be seen on 70mm film in a cinema. People who saw it at a 35mm-only cinema (the vast majority) would have experienced a slightly inferior picture quality. The 4K scan of the film may or may not match the quality of the original film depending on the graininess of the film, but from a 70mm source it will probably be slightly inferior to the film version, however grainy 35mm prints have grains bigger than a 4K pixel, so the transfer is about the same quality. Someone watching the film on a VCR (or even a DVD) isn't getting anywhere close to the original intended experience. They may still get a lot of the atmosphere from the experience, but it was always a sub-par experience compared to the cinema, and most people who who watched films on a VCR were only too well aware of that as even most commercial VCR tapes weren't up to the standard that was possible for broadcast OTA TV especially for PAL. In contrast, running a video game designed for NTSC or PAL TV's, usually somwhere between 320 and ~350 horizontal pixels that were then encoded to NTSC or PAL, so keeping the original pixel accuracy on the luma component of the colour, but smudging colours to a lower accuracy in the chroma (each line was ~280 colour clocks, but some of these weren't visible, so maybe estimate 200 pixels horizontally), and finally output to a TV with a different arrangement of pixels again depending on the mask in the TV. It was pretty much accepted that single pixels wouldn't be the colour they were supposed to be, and many pixel games used dithering to create new colours and colour gradients to make up for limited palettes from the hardware and usually even more limited palettes from the colour look-up tables (because memory was a premium, systems were often 4 colours from a choice of 16 or similar). Even well before the advent of LCD TVs, some games looked a bit ugly when using a higher quality RGB computer monitor (e.g. the 1080 for the Amiga) compared to using a TV, even though the monitor was vastly superior for applications. To compensate for the relatively low refresh rate of interlaced broadcast TV, the phosphor on the screen was designed to decay in brightness slowly so that the alternate lines would fill in the gaps left from the previous field to give the impression of a higher vertical resolution (this is why NTSC is usually called 480i30 and PAL 576i25) but in practice, most games treated each field individually and depending on the timing of the signal they output, it might not even be actually interlaced at all, so games really ran at 240p60 (NTSC) or 288p50 (PAL) with some blur between frames from the phosphor which wasn't designed for that. As an aside, this is why live TV broadcasts (i.e. using an old TV camera rather than a film scan) look so jaggy on a modern TV - although they are interlaced, the two fields aren't independent when the camera or subjects are moving as the image is captured twice in different positions. This looks OK on a TV, because the phosphor has decayed a bit and the newer image is slightly brighter, but also because the image is effectively blurred across a couple of frames anyway. Later studio cameras in the digital age captured the whole image at once and output a genuine interlaced signal where the odd and even frames were coherent. When you try to play a game designed for CRT on a modern LCD TV, first of all, you don't get any of the effects mentioned above, you just get a crisp square that fills the entire pixel space. Some TVs allow a "clarity" or "crispness" adjustment that blurs the image a bit, but fundamentally the image is never what was intended originally, nor how it was perceived when seen on a CRT. Attempts to up-scale these low-resolution images to take advantage of the higher-resolution from the LCD can often lead to even weirder artifacts - e.g. you might like an upscaler to recognise a diagonal edge and create a smooth diagonal, but this can lead to weird diamond patterns in dithered areas. And some TVs might also try to de-interlace the image, leading to the jaggies I mentioned above from live TV cameras. All in all, games from a certain era were designed to look good on the output technology of the time, and modern TVs generally do a terrible job of replicating that experience unless you go through a specialised CRT filter which tries to replicate in software the effect you'd get if you stuck a hi-resolution digital camera in front of an old CRT displaying the signal. Some of these are actually pretty good, but vastly different from what you'd get plugging your old game directly into a TV. Films were generally designed for watching in the cinema, and were broadcast on TV at a lower quality, and sold on VCR at an even worse quality. Watching a high quality transfer on a blu-ray is much closer to how they were intended to be seen, and not only doesn't create any weird artifacts by being better quality than you'd have seen on your CRT showing a VCR tape, it'll actually reveal new details that were always there in the film that were just missing on the VCR version.

MenhirMike 3y ago

The nice thing about High DPI is that you can re-create the aperture grille/shadow mask of a real TV to get the actual sub-pixel pattern. That requires a high resolution since you need both enough pixels (since every original "pixel" requires 4+ pixels now) and small enough pixels (to make the effect not overly exaggerated - unless you want to emulate a low end TV with gigantic dot pitch). Also, no more "fake" scanlines because the entire mask is fake :) Also, issues with pixel aspect ratio (8:7 vs 5:4 vs 4:3, square vs rectangular pixels) can be resolved while still being able to scale by exact integers rather than floats. It's funny, but 4K displays might really be one of the best ways to play retro games nowadays, I'm hoping that upscalers (like the Retrotink 4K, or maybe future OSSC upgrades) will bring some of the stuff we've been doing in emulators to real hardware as well (though yes, that thing will cost several hundreds of dollars, so emulation is probably going to stay the preferred option for many). Now we just have to solve losing the sync signal for games that switch between 240p and 480i during gameplay, or that don't have an exact 60 Hz refresh rate - Variable Refresh Rate displays are actually a real opportunity here as well. Oh, and find a way to all of that without introducing any display processing latency.

rob74 3y ago
So it takes a 14" 4:3 4k resolution OLED display (does such a thing even exist?) and a top-of-the-line GPU to emulate a 30+ year old 14" CRT monitor?
- MenhirMike 3y ago
  And even then it's probably still not perfect since you're sending to a framebuffer instead of controlling the beam directly, which adds at minimum 1 frame of latency. (Unless there is a "real-time" way to send a picture over HDMI)
  - nyanpasu64 3y ago
    Super Mario World and many other SNES (and later) games spends two frames after a controller jump input sending unchanged frames on-screen, before showing a frame where the player is jumping (tested in slow-motion camera). Emulators (and possibly FPGAs) can use run-ahead to skip past one or more of these "no change" frames, reducing input latency to match or surpass console latency (https://github.com/higan-emu/emulation-articles/tree/master/input/run-ahead https://github.com/higan-emu/emulation-articles/tree/master/...). Another strategy is to delay polling input computing the next frame until the end of the previous frame being drawn (RetroArch frame delay). This does not rely on the game not responding immediately to controller input, but is more prone to dropping frames if your CPU gets occupied and can't run your emulator for a few milliseconds. It is possible to compute and display images in near-real-time over HDMI, but this technique is quite niche (https://blurbusters.com/blur-busters-lagless-raster-follower-algorithm-for-emulator-developers/ https://blurbusters.com/blur-busters-lagless-raster-follower...).

WithinReason 3y ago

In addition, high DPI/refresh screens can recreate any CRT you have a shader for, or only recreate the "artistically relevant" aspect, the blur and gamma characteristics and not recreate the irrelevant flaws of CRTs.

bluescrn 3y ago

High DPI screens give more options for exact integer scaling too, before putting shaders over the top. The other often-forgotten issue is running 50Hz PAL games smoothly. This should be getting easier, with more screens able to run at 100Hz, but it's rare to see an emulator actually support this. Would be nice if modern 4:3 panels were available, too (And not just for retro gaming, they were more practical than 16:9 for work PCs)

willis936 3y ago

I think we are still several years away from flat panels being able to sinulate phosphor persistence and the strobed nature of CRTs. CRT phosphors decay with a time constant of 1-2 ms, so you'd want at least 1000 Hz to properly simulate it. Even if you couldn't get that fast you could at least get the meat of it with backlight strobing that has ~25% duty cycle. This gives incredible motion clarity but it is very rare on modern displays. I don't really know why. Display manufacturers should be giving users the option to reduce brightness by 75% for motion clarity if they want it. It will also be a while yet before modern displays can hit the product of motion clarity and brightness that CRTs have hit since before we were born.

zozbot234 3y ago
> with backlight strobing that has ~25% duty cycle. Yes, that's what happens when you set screen brightness to the lowest setting. And guess what, it looks terrible.
- willis936 3y ago
  Similar, but not exactly. The details matter. The strobing needs to be synchronous with the frames. Adding flicker without the motion clarity benefit looks bad. Strobing in sync with content looks amazing. How many people complained about 60 Hz flicker on CRTs over their 70 year reign? https://forums.blurbusters.com/viewtopic.php?t=6519 https://forums.blurbusters.com/viewtopic.php?t=6519