The video mentions that they get 15 ms end-to-end latency on a 360 Hz monitor in Fortnite. So that's what it takes for a modern system to finally beat the latency that you used to get on, say, an NES connected to a CRT. Still an order of magnitude above the limits of perception though [2].
I often wonder at what cost, could we get it down to Sub Ms. Where everything from Input, Video and Audio are sync to the precision of 1ms. There used to be very little incentive to do so. Now that Gaming has taken over I hope it will develop some market perception and value so we could finally move into that direction.
The age of Instantaneous Computing.
Worth noting that unlike some of the other sources being discussed, this source of latency is more due to physical constraints than bad engineering or bloated software. Keyboards are limited by the physical travel time & de-bounce of the mechanical switches themselves.
So this is more a tradeoff of using mechanical keyboards at all rather than "gah bloated electron" or whatever.
The other common peripheral, mice, don't have this mechanical constraint. They can even achieve sub-10ms for clicks due to the difference in switch expectations ( https://www.rtings.com/mouse/tests/control/latency )
EDIT: Also 30+ms seems to be quite far off. Cherry MX's specs are around 5ms, and I'm getting 8ms playing around with this tool: http://blog.seethis.link/scan-rate-estimator/
I mean, yes but not really? There's very real speed limits to the human finger, after all.
But the times given above are also quite far off - the actual keyboard numbers seem to be more in the 5-15ms range, not 30+ms. At least, my mechanical gaming keyboard is hitting 8ms on this test: http://blog.seethis.link/scan-rate-estimator/
If you only have to worry about false deactivation and there's no line noise, and your keys always stay down long enough to be caught by your scan interval (or they trigger an interrupt), then probably yes. If you have to worry about false activation, then probably no.
You certainly don't want to low-pass filter the whole thing, or otherwise wait for the contact to settle before reporting the keystroke or mouse click.
In general, you can make a denouncer with zero latency: the receiver still triggers on the first logic change for idle to active, but then gates any further changes for a while.
(At least, that’s how I design all my debouncers.)
There may be aspects that are specific to a matrix keyboard configuration that prevent this...
It seemed a reasonable number for a goodish keyboard on that list
An interesting set of numbers, but doesn't tell you all that much about the hardware quality itself. The actuation point and travel distance of mechanical switches is itself an endless source of user opinions & discussions.
The latency in the hardware before the signal makes it to the usb (for most keyboards, even specialised gaming keyboards this is like 30ms, which is 2 frames).
There is also the latency from when the monitor gets a signal to when the pixels have perceptually finished transitioning. This can be 10s of ms too.
So even if the OS has 0 latency, and the monitor measures that, you could still easily observe a latency of say 60ms.