2 ms·

LCDs aren't capable of pulsing at 15kHz. The twisting/untwisting of the liquid crystals is an electromechanical process and very slow (compared to a racing elec

LCDs aren't capable of pulsing at 15kHz. The twisting/untwisting of the liquid crystals is an electromechanical process and very slow (compared to a racing electron beam). Even though the fastest gaming LCD monitors claim a 360Hz refresh rate, they cannot get anywhere near this 2.8ms latency (implied) when going from black to white (0 to 100% brightness). Of course, the monitor manufacturers go to great lengths to avoid talking about it, so the whole industry is flooded with a bunch of marketing material to distract from the issue.

Dylan16807 4y ago
> LCDs aren't capable of pulsing at 15kHz. Yeah, I know. But you don't need the LCD to pulse, you need the backlight to pulse. An LCD might still have issues switching fast enough, but an HDR OLED tuned to 15kHz PWM might be able to handle it. If it was designed with minimum latency in mind of course. Most screens buffer a full frame and that won't work. But playing duck hunt doesn't require timing the actual beam as it sweeps across the screen. You just need to be displaying rows with a buffer that's no more than a few rows high, and have the rows flicker. Also many third party controllers don't care that much about the flicker.
- chongli 4y ago
  Oh, with OLED you could probably design it to mimic the raster scan of a CRT perfectly, cascading the row and column signals along at 15kHz. The issue is, who is going to build that? I don't think Duck Hunt is too high on the priority list for OLED panel makers. The really sad thing is that some day all of the CRTs will be dead and all of the expertise to build them too. The tooling and factories are already gone, so it's unlikely new CRTs will ever be built, unless some Ben Krasnow-esque super-hobbyist gets really passionate about it.
  - Dylan16807 4y ago
    > Oh, with OLED you could probably design it to mimic the raster scan of a CRT perfectly, cascading the row and column signals along at 15kHz. You could but it wouldn't have the same brightness as it sweeps so I don't know if that's good enough to trick a light gun by itself. But I still think you shouldn't discount LCD. If you can get an LCD to switch a good fraction of the way in half a millisecond, and use the right backlight, you could make duck hunt work. > The issue is, who is going to build that? I don't think Duck Hunt is too high on the priority list for OLED panel makers. To trick the frequency filter might be too much effort, but the latency of having each row come along instantly might get some effort into it. Marketing loves low latency.
    - chongli 4y ago
      The low latency claimed by LCD marketers concerns narrow grey-to-grey transitions. Black to white remains as slow as ever. The other issue is all of the other causes of latency along pipeline. The NES emits an composite video signal directly from its video chip, the PPU. This composite signal travels along a coax cable into the back of the TV where it’s split by the analogue circuitry into signals driving the luminance and colour, synchronized to the horizontal and vertical retrace. The whole process happens in less time than it takes to convert that signal into digital before it could even be sent to an LCD. That is, before our LCD display even receives a frame it’s already on the screen of the CRT. The NES is explicitly designed around the NTSC timing structure, with the rendering in the PPU happening “just in time” to be sent to the CRT. There is no place in the NES to buffer a frame.
      - Dylan16807 4y ago
        > The whole process happens in less time than it takes to convert that signal into digital before it could even be sent to an LCD. While that's true, doing the conversion doesn't need to add more than a microsecond of latency. > That is, before our LCD display even receives a frame it’s already on the screen of the CRT. The NES is explicitly designed around the NTSC timing structure, with the rendering in the PPU happening “just in time” to be sent to the CRT. There is no place in the NES to buffer a frame. An LCD doesn't have to buffer a frame either. I believe there are models that don't. It can display as it receives, limited by the crystal speed which is still an order of magnitude improvement.

Dylan16807 4y ago

> LCDs aren't capable of pulsing at 15kHz. Yeah, I know. But you don't need the LCD to pulse, you need the backlight to pulse. An LCD might still have issues switching fast enough, but an HDR OLED tuned to 15kHz PWM might be able to handle it. If it was designed with minimum latency in mind of course. Most screens buffer a full frame and that won't work. But playing duck hunt doesn't require timing the actual beam as it sweeps across the screen. You just need to be displaying rows with a buffer that's no more than a few rows high, and have the rows flicker. Also many third party controllers don't care that much about the flicker.

chongli 4y ago
Oh, with OLED you could probably design it to mimic the raster scan of a CRT perfectly, cascading the row and column signals along at 15kHz. The issue is, who is going to build that? I don't think Duck Hunt is too high on the priority list for OLED panel makers. The really sad thing is that some day all of the CRTs will be dead and all of the expertise to build them too. The tooling and factories are already gone, so it's unlikely new CRTs will ever be built, unless some Ben Krasnow-esque super-hobbyist gets really passionate about it.
- Dylan16807 4y ago
  > Oh, with OLED you could probably design it to mimic the raster scan of a CRT perfectly, cascading the row and column signals along at 15kHz. You could but it wouldn't have the same brightness as it sweeps so I don't know if that's good enough to trick a light gun by itself. But I still think you shouldn't discount LCD. If you can get an LCD to switch a good fraction of the way in half a millisecond, and use the right backlight, you could make duck hunt work. > The issue is, who is going to build that? I don't think Duck Hunt is too high on the priority list for OLED panel makers. To trick the frequency filter might be too much effort, but the latency of having each row come along instantly might get some effort into it. Marketing loves low latency.
  - chongli 4y ago
    The low latency claimed by LCD marketers concerns narrow grey-to-grey transitions. Black to white remains as slow as ever. The other issue is all of the other causes of latency along pipeline. The NES emits an composite video signal directly from its video chip, the PPU. This composite signal travels along a coax cable into the back of the TV where it’s split by the analogue circuitry into signals driving the luminance and colour, synchronized to the horizontal and vertical retrace. The whole process happens in less time than it takes to convert that signal into digital before it could even be sent to an LCD. That is, before our LCD display even receives a frame it’s already on the screen of the CRT. The NES is explicitly designed around the NTSC timing structure, with the rendering in the PPU happening “just in time” to be sent to the CRT. There is no place in the NES to buffer a frame.
    - Dylan16807 4y ago
      > The whole process happens in less time than it takes to convert that signal into digital before it could even be sent to an LCD. While that's true, doing the conversion doesn't need to add more than a microsecond of latency. > That is, before our LCD display even receives a frame it’s already on the screen of the CRT. The NES is explicitly designed around the NTSC timing structure, with the rendering in the PPU happening “just in time” to be sent to the CRT. There is no place in the NES to buffer a frame. An LCD doesn't have to buffer a frame either. I believe there are models that don't. It can display as it receives, limited by the crystal speed which is still an order of magnitude improvement.