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Keyboard latency

danluu.com

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Re: Keyboard latency

#91

Post by DINKDINK »

colanderman wrote: post #9

I'm surprised the "humans don't notice 100 ms" argument is even made. That's trivially debunkable with a simple blind A/B test at the command line using `sleep 0.1` with and without `sleep` aliased to `true`. To my eyes, the delay is obvious at 100 ms, noticeable at 50 ms, barely perceptible at 20 ms, and unnoticeable at 10 ms. Not to mention that 100 ms is musically a 16th note at 150 bpm. Being off by a 16th note e…

>Not to mention that 100 ms is musically a 16th note at 150 bpm. Being off by a 16th note even at that speed is – especially for percussive instruments – obvious.

There's a difference in constant, but consistent lag (delay) and variation of lag variance(lag)>0. If one note is a 16th note off that is lag variance.

Re: Keyboard latency

#92

Post by pdkl95 »

colanderman wrote: post #9

I'm surprised the "humans don't notice 100 ms" argument is even made. That's trivially debunkable with a simple blind A/B test at the command line using `sleep 0.1` with and without `sleep` aliased to `true`. To my eyes, the delay is obvious at 100 ms, noticeable at 50 ms, barely perceptible at 20 ms, and unnoticeable at 10 ms. Not to mention that 100 ms is musically a 16th note at 150 bpm. Being off by a 16th note e…

> strike a key less than 100 ms after some visual stimuli, I'm sure I couldn't do it

The video game "Super Hexagon"[1] is a surprisingly interesting demonstration of this limitation, and how the mind tries to workaround the problem. The higher difficulties ("hexagonest"[2]) seem impossible at first. In the easier levels you can react, but now the time it takes to see the scree, parse the simple graphics, recognize that you need to turn left to avo##CRASH##...##GAME OVER##, You quickly learn that if you think about the game, you are guaranteed to fail due to insufficient reaction time. Winning requires a mental state possible related to meditation: don't think, let the muscle memory do it's job (maybe from a faster path limited to the spinal-chord and brain-stem?).

[1] https://www.youtube.com/watch?v=UrPXBSh4mqU

[2] I finally got a winning 62.09s a few days ago, after many months starting at a high score of 58.57

Re: Keyboard latency

#93

Post by lelandbatey »

munchbunny wrote: post #71
alasdair_ wrote: post #36

Isn't a big part of the reason "gaming" keyboards cost so much because they can register more than three keys (sometimes four) being hit at the same time - something many cheaper keyboards cannot do due to the way they are wired?

Yes, n-key rollover sometimes comes up. In practice, I've only had it become an issue in the wild either when more than one player is sharing the keyboard or, in some rare games, primarily simulators, where you might need to hold multiple keys.

I've had keyboards which where marketed as professional keyboards have very obvious problems with this. Specifically, I had a Logitech MX5500 and if you where holding down the 'D' key and then pressed the 'S' key, the keyboard would never send the 'S' key (though I might remember those keys backwards). This is a problem because many a video game has you use the 'WASD' keys as direction keys to control movement, so trying to move backwards and to the right would fail.

So it's not like nobody experiences this problem.

Re: Keyboard latency

#94

Post by feelin_googley »

"It all started because I had this feeling that some old computers feel much more responsive than modern machines."

s/modern/recent/

"For example, an iMac G4 running macOS 9 or an Apple 2 both feel quicker than my 4.2 GHz Kaby Lake system."

Kaby Lake system running OSX? I have one of the last G4 that came with OS9. Based on intuition it would make audio applications "feel" slower, when OSX came out I did not "upgrade", despite the marketing at the time. I guess I am not the only one.

"It turns out the machines that feel quick are actually quick, much quicker than my modern computer - computers from the 70s and 80s commonly have keypress-to-screen-update latencies in the 30ms to 50ms range out of the box, whereas modern computers are usually in the 100ms to 200ms range."

"... where we are today, where can buy a system with the CPU that gives you the fastest single-threaded performance money can buy and get 6x the latency of a machine from the 70s."

Methinks when someone spends that kind of money on a system, they will never accept findings like these. They are not likely to respond "inquisitively" to someone who describes achieving better speeds with a "less powerful" system that costs a fraction of what they paid. More likely, they will try to discredit them.

Re: Keyboard latency

#95

Post by jetpacktuxedo »

munchbunny wrote: post #71
alasdair_ wrote: post #36

Isn't a big part of the reason "gaming" keyboards cost so much because they can register more than three keys (sometimes four) being hit at the same time - something many cheaper keyboards cannot do due to the way they are wired?

Yes, n-key rollover sometimes comes up. In practice, I've only had it become an issue in the wild either when more than one player is sharing the keyboard or, in some rare games, primarily simulators, where you might need to hold multiple keys.

ghosting can also cause issues with holding multiple keys at once and is more likely what they are referring to. Details here: https://www.microsoft.com/appliedsciences/antighostingexplai...

Re: Keyboard latency

#96

Post by wmf »

skykooler wrote: post #80
M4v3R wrote: post #59

Earlier quoted context omitted.

I don't have a way to measure raw USB events, but it takes around 90 ms between me pressing a key on the Macbook's (2015 model) keyboard and a character showing in the TextEdit.app.

Some of that is surely in the OS and display however. I wonder how you'd go about measuring the latency of a laptop keyboard?

Patch into the flex cable between the keyboard and motherboard. Maybe if Dan and bunnie cross paths...

Re: Keyboard latency

#97

Post by nitrogen »

munchbunny wrote: post #71
alasdair_ wrote: post #36

Isn't a big part of the reason "gaming" keyboards cost so much because they can register more than three keys (sometimes four) being hit at the same time - something many cheaper keyboards cannot do due to the way they are wired?

Yes, n-key rollover sometimes comes up. In practice, I've only had it become an issue in the wild either when more than one player is sharing the keyboard or, in some rare games, primarily simulators, where you might need to hold multiple keys.

If you hold C for crouching, you can't move on some diagonals and switch weapons at the same time. Many games/gamers use shift or ctrl now for crouch to work around that.

Re: Keyboard latency

#98

Post by JimmyAustin »

tomxor wrote: post #89
spott wrote: post #87

Earlier quoted context omitted.

25ms is 1.5 * (1/60)... Is your monitor running at 60Hz?

Your probably right, it's an old TN panel in a 10yr old laptop... I'm gona have to steal someones shiny modern IPS in a minute :P (I know they are generally slower response but it's 10 years newer so you never know) [edit] No IPS still super slow. How common are >60Hz computer displays these days?

Common for gamers, relatively unknown for everyone else. They typically go up to 144Hz.

Re: Keyboard latency

#99

Post by jetpacktuxedo »

lelandbatey wrote: post #93
munchbunny wrote: post #71

Earlier quoted context omitted.

Yes, n-key rollover sometimes comes up. In practice, I've only had it become an issue in the wild either when more than one player is sharing the keyboard or, in some rare games, primarily simulators, where you might need to hold multiple keys.

I've had keyboards which where marketed as professional keyboards have very obvious problems with this. Specifically, I had a Logitech MX5500 and if you where holding down the 'D' key and then pressed the 'S' key, the keyboard would never send the 'S' key (though I might remember those keys backwards). This is a problem because many a video game has you use the 'WASD' keys as direction keys to control movement, so tr…

As mentioned in my other comment, that is a symptom of ghosting, not of being limited to the standard 6-key rollover set by the usb spec.

Re: Keyboard latency

#100

Post by rconti »

deathanatos wrote: post #63
bhj wrote: post #37

Earlier quoted context omitted.

Agreed, and I don't understand the hate many people (seem to) have for them - the most ergonomic keyboards are those that require the least amount of repetitive motion. Not that there isn't an adjustment period, but some seem to pull out their Jump To Conclusion mats a little early.

There's essentially no range of motion in a MBP keyboard anymore: there is no difference between not pressing the key, actuating the key, and bottoming out the key. Some people (such as yourself) seem to prefer it, but to me it feels much rougher than comparable keyboards, like typing on a hard plastic surface. There is no give or play in the keystroke. Compared to a Lenovo T460p's keyboard (the other machine I own),…

Because they're talking about USB keyboards they're probably talking about the chicklet Apple "Pro" USB keyboard, not the new MBP's built in keyboard. Which, I agree-- I've only typed on the actual laptop itself a handful of times, but man, those key movements are SHORT and I'm not sure I really like it. Time will tell, though -- I originally felt the same way about the chicklet keyboards i love now.
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