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Keyboard latency

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Re: Keyboard latency

#171

Post by tesseract »

wolf550e wrote: post #170
tesseract wrote: post #166

I probably missed something but: > It’s possible to get down to the 50ms range in well optimized games with a fancy gaming setup, and there’s one particularly impressive consumer device that can easily get below that. Is the device in question mentioned anywhere?

Yes, the apple magic keyboard with 15ms latency.

Oh. I guess I interpreted the passage I quoted as referring to a complete keypress-to-display latency, which wasn't tabulated in the article (vs. keypress-to-USB). And the Apple keyboard isn't that much of an outlier with the next-fastest keyboard coming in at 20ms. So I'm a bit let down but I'll accept it.

Re: Keyboard latency

#172

Post by mrob »

xbkingx wrote: post #84
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…

The more obvious example is to watch a video encoded at 10 frames per second followed by a 30 fps video. Does it look different? If yes, something's wrong with the statement There are plenty of examples on YouTube if anyone's interested.

That's not a fair comparison, because we can distinguish very high frame rates (eg. 1000fps vs 3000fps) by watching how the perceived image changes in reaction to eye movement. Consider an LED strobing at 100Hz. This is above the flicker fusion threshold, so with motionless eyes it will appear steady, but if you flick your eyes from side to side you will see multiple images (phantom array effect). This is limited to some extent by saccadic masking, but never perfectly, and saccadic masking strength varies from person to person.

Similarly, limited frame rate makes it impossible to keep the image at exactly the same place on the retina during smooth pursuit eye tracking, causing perceived blur that wouldn't be seen with a real life moving object.

Seeing a difference with 1000fps video doesn't mean we have 1ms temporal resolution perception, it just means some test signals allow conversion of temporal information to spatial information by eye movement. It doesn't generalize to arbitrary visual events. To investigate keyboard latency sensitivity properly there's no substitute for ABX testing of actual keyboards.

Re: Keyboard latency

#173

Post by deong »

bhj wrote: post #37
andyfleming wrote: post #24

Earlier quoted context omitted.

That's fine though. It's about the experience end-to-end. I love the apple keyboards. I still type faster on them than other keyboards, including high-end mechanical keyboards. The short keys and actuation feel responsive, yet I've never felt like I've accidentally triggered a key.

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.

Not all repetitive motions are equal. It's far more complex than that. The relative angles your joints are held at during the motion, rotations, etc, are far more important than just some simple metric around number of repetitions or distance travelled. Saying less motion is better is like saying lifting less weight is better. You'll sooner fuck up your back lifting 40 pounds incorrectly than 80 pounds correctly.

Re: Keyboard latency

#174

Post by sturmeh »

Completely missing the fact that enthusiast keyboards still prefer PS/2 for NKRO (no key-rollover) and HW interrupt support which results in sub 10ms delays.

Re: Keyboard latency

#175

Post by lightedman »

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…

"To my eyes, the delay is obvious at 100 ms, noticeable at 50 ms, barely perceptible at 20 ms, and unnoticeable at 10 ms."

That's how it goes with my ears when recording as well. Most "Live feedback" mechanisms for guitar programs (heck even computer-made guitar hardware) have about 50ms of latency, which is quite disconcerting when you're doing something heavily timing-based. 10ms is almost imperceptible to me (sounds more like the tiniest slightest reverb delay) and 5ms might as well be realtime as far as I'm concerned.

An example, in Windows 10, I could go to the built-in mixer, turn on the "Listen to this device" and play with my guitar plugged right into the computer, and you're looking at about 100 ms or so of latency. Completely unacceptable when you're listening to a metronome to keep on time. Alternatively, I can go to the Realtek HD Audio Manager in the taskbar (because I installed the actual RealTek driver package instead of relying upon the Windows drivers) and un-mute the line in, and even with an amp and mixer board in-line before the computer, the feedback is essentially instantaneous, which allows for pre-baked instant reaction times (eg muscle memory) to work and record in time with the metronome (or backing track.)

Re: Keyboard latency

#176

Post by sturmeh »

SebiH wrote: post #6
yathern wrote: post #4

Earlier quoted context omitted.

For what it's worth, that answer is now 8 years old - I'm curious if this has changed since then.

A more recent video claims that the PS/2 advantages are negligible even for serious gamers (around 3:40) https://www.youtube.com/watch?v=AWkvzycD5PE

Most importantly it removes the penalty of using a 1000hz scanning input which can have an adverse affect on the cpu whilst providing a better (yet insignificant) result.

Re: Keyboard latency

#177

Post by lightedman »

sturmeh wrote: post #174

Completely missing the fact that enthusiast keyboards still prefer PS/2 for NKRO (no key-rollover) and HW interrupt support which results in sub 10ms delays.

Not all PS/2 Keyboards had NKRO, sadly. I know this yuck HP media keyboard won't.

Re: Keyboard latency

#178

Post by sturmeh »

kllrnohj wrote: post #123
matthavener wrote: post #3

PS/2 keyboards are used by serious gamers because the scan rate is higher than USB. See https://superuser.com/questions/16893/do-usb-or-ps-2-keyboar...

I'm unaware of any pro gamer (or streamer) that's using PS/2, and that's about as serious a gamer as you get. Most are using a late model mechanical keyboard connected via USB, often with lots of RGB just because. I think the only PS/2 holdouts you'll find are the old Korean Starcraft players that are still using a Qsenn DT-35.

PS/2 supports lots of RGB, I'm using one, because using the USB costs CPU where as the PS/2 does not, and PS/2 gives NKRO and lower latency, however insignificant they are.

It's entirely a preference based thing, the most relevant factor would be whether or not you need to hot swap it.

Re: Keyboard latency

#179

Post by sturmeh »

HugoDaniel wrote: post #14
matthavener wrote: post #3

PS/2 keyboards are used by serious gamers because the scan rate is higher than USB. See https://superuser.com/questions/16893/do-usb-or-ps-2-keyboar...

do serious gamers avoid v-sync ? even at 120Hz they get at least ~8ms * 2(double buffer) latency right ?

Of course, they've turned to gsync or leave vsync off.

Re: Keyboard latency

#180

Post by tscs37 »

Phrodo_00 wrote: post #154
stefco_ wrote: post #133

Earlier quoted context omitted.

> I immediately switched to skeptic mode when I saw no actuation points or normalization for travel distance. All this is showing is that to move further it takes longer. I thought his explanation (that delay from the start of the motion) was a good one. Unless someone is starting with a key partially depressed/near the actuation point (which you certainly could do), the key travel time is going to be a part of the p…

But that's not how people game. When I play FPS on my MX Blue keyboard I don't make my fingers sit above the keys, but into the keys, depressing them almost until they're in the activation point. I'd guess people on linear switches don't do this, but they also probably slam their keys faster. The "gaming" keyboards he used were also pretty shoddy. Now, I'm not necessarily saying gaming keyboards offer better latency,…

That's rather anecdotal. Counter anecdote: I do not hover my fingers, mostly because I have Cherry Clears, I hammer the key.

Most people don't partially depress keys to my experience.

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