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Comment by aeyes | Hacker News Reader

The problem is the significant input lag most modern TVs have.

The bigger problem is sample-and-hold blur. When you watch a moving object your eyes move smoothly to track it ("smooth pursuit"). If the frame is displayed for more than a brief moment then the image on your retina will be smeared by that eye motion. For sharp looking motion you need either strobing/flicker, or very high frame rate, and many games don't support very high frame rates. Blurbusters has a good overview:

https://www.blurbusters.com/faq/oled-motion-blur/

I don't get why they don't make strobing LCDs. We have local dimming and LEDs can strobe well past CRT refresh rates, so why not strobe each local dimming region at e.g. 75Hz?

Many of the gaming LCDs have an option to do that (some incorrectly label it as black frame insertion). It is painful to look at when active so no one uses it.

Sony's mid- to high-end LCD TVs have a feature they call "X-Motion Clarity" that pretty much does that -- local dimming zones independently strobing (at 120Hz) depending on picture content/motion. Seems to work well.

Search ULMB or Lightboost

VR headsets do this. They are one of the most common applications due to how important tracking motion is, and also because they refresh at a higher rate by design - for content at lower refresh rates (60hz for a game) the flicker is very noticeable. If you've used an Oculus Go, some games run at only 60hz and the backlight flicker becomes quite noticeable.

You can strobe at a higher rate than the refresh rate; IIRC film projectors would strobe at 72Hz with a frame rate of 24Hz.

If you do that and the eye is tracking (as in the context, here) then you get ghost images rather than blur, which is still quite distracting. That's the reason that a lot of films avoid mid-speed panning shots.

That is becoming less of a problem than it used to be. There are upscalers that can, with zero lag, take an RGB signal and output something over HDMI that a modern display can use. And there are certain displays (generally computer monitors) that can deliver sub-frame input lag with used with a good upscaler. It's not QUITE the same as playing on a CRT, but it's good enough for speedrunners of many retro games.

Such a setup isn't cheap, but it's far more reliable and space-efficient than a giant CRT.

I recently purchased a RetroTINK-2X, which is an inexpensive FPGA-based line doubler. It works on a line-by-line basis (as opposed to frame-by-frame like most upscalers) and so lag is virtually nonexistent. I don't have any experience of the more expensive setups like the OSSC or XRGB but it works great for my old consoles.

That said, I still generally prefer to use my PVM CRT monitor for gaming for reasons already discussed in this thread. It really can't be beaten.

Not on modern TV's and monitors. They have less than 2ms latency now.

The vast majority don't, you can get one that does but you have to do your research. The "response time" listed in monitor/tv specs is not the same as the input lag.

TVs are especially bad, in the default mode some of them have ~200ms input lag. "Game Mode" usually brings it down to more like 20ms though.

Edit: did a google, don't know how accurate these are: https://www.rtings.com/tv/tests/inputs/input-lag

https://www.rtings.com/tv/tests/inputs/input-lag

It seems most get under 20ms lag when put into game mode, which I'd think is what matters to most people. At that point, when it isn't daisy-chained with any other lag (so a wireless controller delay will make a difference), it's imperceptible to me. I am not a professional gamer though, and from what I understand the higher refresh rates that pro gamers use (such as a 240 Hz monitor) have measurable improvements in their performance as gamers.

Haha looks like we googled the same thing at the same time.

This seems to just be TVs too - monitors get much better numbers. I find higher input lag to be much less of an issue when using analog sticks vs a mouse.

For me at least the difference between ~2ms and ~10ms input lag is very noticeable when aiming with a mouse, but basically imperceptible with say a wired 360 controller (I'm assuming the 360 controller isn't adding significant input lag itself though).

Also, latency claims are often misleading. For example, the 2ms response time is limited to grey-to-grey transitions.

A 20ms response time still means the signal is dropping every fifth frame in a 60 fps game.

> A 20ms response time still means the signal is dropping every fifth frame in a 60 fps game.

Could you reword this?

response time has little to do with latency, it's purely a property of the panel. At 60Hz refresh, an LCD will have a minimum of 16.7ms latency because it buffers an entire frame before displaying. 20ms of latency would mean there is additionally 3.3ms of lag, not that it takes 20ms for each frame (it's already buffering the next frame in those 3.3ms, so the next frame will be displayed 16.7ms later).

Many TVs buffer several frames for video processing in their default mode, which is why they can have 100s of ms of latency when not in game-mode; the response time is identical regardless of which mode it is in though, as the response time is purely a property of the panel.

Are you sure all LCDs buffer frames for a full frame duration before displaying? I haven't heard that before. I was under the impression that they basically start displaying them as soon as the GPU sends the frame - any buffering being done on the GPU.

Thanks for asking. I'm pretty sure I was wrong. At 60Hz refresh rates it takes 16.7ms to send a full frame to the display, so the minimum latency is 16.7ms even with a CRT (Which has no buffering).

2ms sounds like maybe OLED.

That's simply completely false. You are talking about transition times. To my knowledge there are zero monitors with less than one frame input lag, which is more than 4 ms even for the rare 240 Hz screens and around 7 ms for the average 144 Hz gaming screen.

An excellent gaming screen like a PG258Q might have GTG of 1 ms but at the full 240 Hz it still has about 5 ms of input lag.

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