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Perceivable input lag of 10ms and below

Everything about input lag. Tips, testing methods, mouse lag, display lag, game engine lag, whole input lag chain, VSYNC OFF vs VSYNC ON, and more! Input Lag Articles on Blur Busters.

Perceivable input lag of 10ms and below

Postby MatrixQW » 05 Mar 2019, 12:21

https://www.youtube.com/watch?v=vOvQCPLkPt4
Here you can see the difference with 1ms and 10ms. Would have been great to see 2ms and 5ms also.

https://dl.acm.org/citation.cfm?id=2557037
Here an experiment with participants.
While participants performed dragging and scribbling tasks, very low levels of latency could be discriminated, i.e., ~1 versus 2 milliseconds while dragging

Some people can't notice 4ms from 8ms, but the truth is that even a 2ms difference is noticeable.
It will also depend on the game.
Last edited by MatrixQW on 05 Mar 2019, 15:26, edited 1 time in total.
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Re: Perceivable input lag of 10ms and below

Postby Sparky » 05 Mar 2019, 14:41

It also depends on the absolute input lag, 2 vs 4 ms might be easily noticeable, but 50 vs 52 definitely wouldn't be. This is a big problem, because it means you can't trust feel based AB tests, unless you also measure the absolute latency.
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Re: Perceivable input lag of 10ms and below

Postby MatrixQW » 05 Mar 2019, 15:21

Yes it does. For ping while playing you would not notice, but since we are talking about low input lag values for monitors it can make a difference.
Blur reduction increases input lag a bit and people feel it, even if they are playing with 50ms.
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Re: Perceivable input lag of 10ms and below

Postby Chief Blur Buster » 05 Mar 2019, 22:33

Adding an embed of this so readers can play without leaving the forums --
Yes, it's a famous video by Microsoft Research about input lag and a 1000Hz touchscreen test:

phpBB [video]


I already have this video in Blur Busters Law: The Amazing Journey To Future 1000Hz Displays
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Re: Perceivable input lag of 10ms and below

Postby Chief Blur Buster » 05 Mar 2019, 22:41

Definitely perceivable.

There are many "milliseconds matters" situations for these timescales, which I've historically posted here at Blur Busters. I'll re-quote them here again:

Chief Blur Buster wrote:
niftucal wrote:There's also a pending optimization to improve latency with v-sync disabled but I didn't consider it important since it's minor (a few ms at most). Options specific to latency are planned but will require more knowledge from users to apply properly and are meant for specific use cases.

Oh yeah!
You'd be surprised how important it is to respect the unexpected millisecond.
Not important to everyone, but it's something meritworthy of open mind.

I've even commissioned an article by a peer reviewed researcher on eSports-league reaction times (Input Lag and the Limits of Human Reflex). The millisecond is often easy to dismiss, but there's a few effects behind the millisecond too, that are often easier to understand for laypeople.

To me, a millisecond usually doesn't matter in my fun casual competitive play. But I've learned to keep an open mind about the importance of the millisecond here at Blur Busters.

The Cross-The-Finish-Line Effect. You don't need to feel the millisecond to benefit from the millisecond. Basically the Olympics 100 meter sprint finishers can be just milliseconds apart. Likewise, this situation happens often in a "both see, react, frag" simultaneous situations, like seeing each other at the same time and shooting at the same time -- that's what I call the "cross-the-finish-line" effect. With pro players, playing off each other, their reaction times are so tightly coupled that the lag difference between two can determine the frag. When Person X and Person Y both average the same reaction time, even a 5ms difference actually statistically matters to that particular professional player pairing. Reaction times often have really tight spreads. This can still persist with millisecond differences smaller than the tick interval. Because it is more likely to roundoff to the previous tick, especially in LAN or low-lag play where network lag becomes less dominant (Oh, and Blur Busters also has a network lag article here submitted by Battle(non)sense).

The Lag-Training Effect. You're often pretrained for a specific lag. Basically aiming at a moving target. Say, archery shoot at a 1000 pixels/second moving target. Or FPS turning 1000 pixels/second shooting without stopping turn. Expert players who has the uncanny capability of shooting without pausing your turn (ala shooting while continuously turning). A 5ms lag increase/decrease means an overshoot/undershoot of your aim by 5 pixels. Now if target was moving 5000 pixels/second, you now have an average 25 pixel overshoot/undershoot of your aim. This persists until you retrain towards the new lag. You don't have to feel the millisecond to notice your aiming feels wrong or statistically off from the sudden change in lag.

The Eye-Hand Coordination Effect. This mainly affects touchscreens, but can also affect virtual reality (e.g. Rift, Vive) and other situations where sync between motion and reaction is much more tightly coupled. See Microsoft Research 1000Hz touchscreen video where the milliseconds actually improves the sync. Imagine your finger sliding 1000 millimeters per second along a touchscreen, a 16ms lag means your screen cursor will follow 16 millimeters behind your finger. Certain kinds of Windows 10 touchscreen game could benefit from lag reductions.

There are other reasons why shaving milliseconds off is quite useful and important for various other roundabout reasons. And in non-lag contexts too we play with milliseconds that ends up unexpectedly generating human-visible effects (e.g. strobe backlights flash length, MPRTs, our 480Hz monitor test, mouse pointer phantom array effects, etc). The bottom line, is we've learned to "respect thy millisecond" and keep an open mind.

It's amazing how many surprises lurk beneath the humble millisecond!


Motion blur context
Also albiet not the topic of input lag, I can see the difference between 0.5ms MPRT and 1.0ms MPRT in display motion blur from persistence when viewing TestUFO Panning Map Test at 3000 pixels/second. These are only readable on CRT or with a good motion blur reduction mode that has an adjustable persistence. Normal ULMB/LightBoost cannot read the street labels but if I adjust down to LightBoost 10% or ULMB Pulse Width below 50% -- I can begin to read the street name labels. With Blur Busters Law, 1ms translates to 1 pixel of motion blurring per 1000 pixels/second. Default LightBoost is approximately 2ms persistence on many monitors, so that's 6 pixels of motion blurring at 3000 pixels/second -- according to the math. And tests do confirm -- you can't read 6-point text when it's completely blurred with 6 pixels of motion blurring that completely obscures the text. Alas, many monitors get dark when you adjust persistence that short though, so most users don't use those settings, but future monitors may be able to brightly achieve <0.5ms MPRT at several hundreds nits.

Frametime context
Also, the frametime difference of 100fps versus 144fps is only 1/100sec (8.3ms) versus 1/144sec (6.9ms). That's barely more than a millisecond difference in frametime, yet 100fps versus 144fps is human visible on TN panels when viewed side by side.

So Yes...Milliseconds do matter at Blur Busters
The bottom line is.... We don't dismiss the humble millisecond around here. Sometimes it doesn't matter but sometimes it clearly does.
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Re: Perceivable input lag of 10ms and below

Postby Notty_PT » 07 Mar 2019, 10:25

Everytime I have a debate/discussion with someone on the web about "human not being able to notice a 3ms input lag difference", I don´t get mad. I get jealous of the person that says and feel it. Because I wish I was like them.

I wish I could play at 60hz/75hz and be happy with my mouse behaviour. I wish I could use any 144hz/240hz monitor and don´t care about its input lag as "every model is the same and you won´t notice a thing". I wish I would never want to have a steady 138-141 framerate and could play at 80 to 110fps instead. I wish I would just pick the cheapest 4k big TV on the store, without worrying about noticing a difference in input lag from a 20ms model to a 13ms one.

Basically I don´t get mad anymore when people start the "you can´t notice" debate. I just get jealous. Because I would spend way less money and I would care way less about this stuff :D

Truth is, can I notice a 2ms input lag difference? Yes I can, sadly. I really can and is too easy to distinguish. At 1ms I would confess it starts to be really really hard, but it also depends on the absolute value. Never did a simple total input lag comparasion with 1 ms vs 2 ms.

Example:

ViewSonic XG2402 144hz (4,1ms input lag by Rtings) vs Benq XL2540 240hz (3,7ms input lag by Rtings).

At same framerate can I notice the 0,4ms difference? Nop, I can´t. In fact this is why I talk about XG2402 so much, because it is extremely fast and at the same framerate you most likely will not notice the difference in input lag against a 240hz model. Sounds crazy, but is the truth. However 240hz panels are not as matured as that 144hz ViewSonic monitor, so 240hz panels can go way lower on input lag in the next years. I guess 4,1ms is the absolute minimum you can expect from a 144hz panel.
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Re: Perceivable input lag of 10ms and below

Postby open » 07 Mar 2019, 11:52

yes we need to push the limit and 1ms is a great standard to reach for. with monitors 1ms in many respects becomes even more important but even with things like network and server client lag you would be surprised.

some modern games have gotten good with network related code at hiding the lag with things like intelligent favor the shooter mechanics. but you would be very surprised if you saw all the details at how much is hiding behind the surface. there is a reason overwatch does pro matches at 144hz server tick rate and super low network lag. one of the main ones is that lag would be apparent and create large discrepancies when observing the server side replays. some missed shots would be hits and the way players would move and accelerate would be different. the lag needs to be as low as possible so the viewers cannot percieve the lag compensation errors that need to be corrected. as a player the experience is different as well.

i think 1ms would be a great standard for all parts of the chain in an ideal world.
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