5 ms·

Gamers aren’t using PS/2 keyboards it’s less about USB and more about the keyboard itself there are plenty of tests of keyboards and PS/2 isn’t anywhere near 1m

Gamers aren’t using PS/2 keyboards it’s less about USB and more about the keyboard itself there are plenty of tests of keyboards and PS/2 isn’t anywhere near 1ms true latency, and often the polling rate even doesn’t matter as much. The biggest latency is the time it takes for the keyboards own SOC to recognize the press with mechanical keyboards there can also be additional latency for things like debouncing depending on the switch in question. Overall the best keyboard you can use today is one with a low latency controller and 1000hz polling rate it will be about 2-3 times “faster” than a PS/2 keyboard.

toopsss 8y ago
Debouncing shouldn’t add any latency. If a mechanical keyboard sold at a price premium adds latency for “denouncing” someone got ripped off.
- dogma1138 8y ago
  Debouncing does add latency how much is dependent on the switch and matrix type as well as the controller. Debouncing isn't limited to keyboards this is a concept in electronic switching. http://www.labbookpages.co.uk/electronics/debounce.html http://www.labbookpages.co.uk/electronics/debounce.html The method of debouncing (software, hardware or both) as well as the "debounce" window which can be set beyond a certain base limit to an arbitrary value has an impact on latency. "Gaming" keyboards that tend to push the limit of what is acceptable for debouncing like the first generation Razer ones have had issues with keys registering multiple times for a single press. Most current keyboards don't use the first "drop" as a keypress and usually count 2-3 drops depending on the switch type, and then also have their window set for key repeat if the key is still pressed which then adds additional latency. Heck even with "normal" keyboards you can sometimes see this in action while keeping a key pressed you might notice that the repeat typing is sometimes jittery that is usually the debouncing in action. The reason why mechanical switches can be worse off than membrane is because of how the electrical contact is made.
  - Palomides 8y ago
    it's a 'common' (I've at least seen it used in various open-source keyboard firmwares) trick to only debounce the key release; if you think about it, there's no reason to wait to report the key press, so debouncing should not add latency.
    - dogma1138 8y ago
      There is a reason because many mechanical switches can be partially actuated, spark and depending on the matrix you can also have cross talk which why you need to wait to make sure it’s an actual key press not the switch just ratteling or some noise on the same line.
    - AlotOfReading 8y ago
      This technique is highly susceptible to noise. I had implemented this in a prototype game controller years back to get latency down and it was plagued by phantom keys when people physically bent the PCB.
  - raws 8y ago
    So what's the best keyboard with the lowest latency?: usb>ps/2 some mecha>membrane? How can a consumer tell which is the better choice? input lag of the different keyboards on the same machine?
    - def_true_false 8y ago
      Switches with high actuation point will have inherently lower latency (measured from the start of the keypress). Check deskthority wiki for the numbers, they should have most mainstream switches listed. Benchmarking the time from switch activation to the computer being aware of the input should be doable (i.e. ignoring display latency and most of the software stack), alas no tech reviewers I know of do it. So no easy way for a consumer to compare products. IIRC someone measured the Wooting One to have ~4ms of latency. It does have a switch with adjustable actuation point (not so useful if you get the clicky version, since you cant adjust the tactile bump and click). Edit: By high actuation point I mean farther from the board, it's usually specified from the start of the key travel, so lower numbers.
monochromatic 8y ago
https://danluu.com/keyboard-latency/ https://danluu.com/keyboard-latency/
- userbinator 8y ago
  Unfortunate lack of PS/2 keyboards in those tests, but the other article linked from there (and discussed here before): https://danluu.com/input-lag/ https://danluu.com/input-lag/ ...shows that the keyboard latency is actually a significant part of input lag.

toopsss 8y ago

Debouncing shouldn’t add any latency. If a mechanical keyboard sold at a price premium adds latency for “denouncing” someone got ripped off.

dogma1138 8y ago
Debouncing does add latency how much is dependent on the switch and matrix type as well as the controller. Debouncing isn't limited to keyboards this is a concept in electronic switching. http://www.labbookpages.co.uk/electronics/debounce.html http://www.labbookpages.co.uk/electronics/debounce.html The method of debouncing (software, hardware or both) as well as the "debounce" window which can be set beyond a certain base limit to an arbitrary value has an impact on latency. "Gaming" keyboards that tend to push the limit of what is acceptable for debouncing like the first generation Razer ones have had issues with keys registering multiple times for a single press. Most current keyboards don't use the first "drop" as a keypress and usually count 2-3 drops depending on the switch type, and then also have their window set for key repeat if the key is still pressed which then adds additional latency. Heck even with "normal" keyboards you can sometimes see this in action while keeping a key pressed you might notice that the repeat typing is sometimes jittery that is usually the debouncing in action. The reason why mechanical switches can be worse off than membrane is because of how the electrical contact is made.
- Palomides 8y ago
  it's a 'common' (I've at least seen it used in various open-source keyboard firmwares) trick to only debounce the key release; if you think about it, there's no reason to wait to report the key press, so debouncing should not add latency.
  - dogma1138 8y ago
    There is a reason because many mechanical switches can be partially actuated, spark and depending on the matrix you can also have cross talk which why you need to wait to make sure it’s an actual key press not the switch just ratteling or some noise on the same line.
  - AlotOfReading 8y ago
    This technique is highly susceptible to noise. I had implemented this in a prototype game controller years back to get latency down and it was plagued by phantom keys when people physically bent the PCB.
- raws 8y ago
  So what's the best keyboard with the lowest latency?: usb>ps/2 some mecha>membrane? How can a consumer tell which is the better choice? input lag of the different keyboards on the same machine?
  - def_true_false 8y ago
    Switches with high actuation point will have inherently lower latency (measured from the start of the keypress). Check deskthority wiki for the numbers, they should have most mainstream switches listed. Benchmarking the time from switch activation to the computer being aware of the input should be doable (i.e. ignoring display latency and most of the software stack), alas no tech reviewers I know of do it. So no easy way for a consumer to compare products. IIRC someone measured the Wooting One to have ~4ms of latency. It does have a switch with adjustable actuation point (not so useful if you get the clicky version, since you cant adjust the tactile bump and click). Edit: By high actuation point I mean farther from the board, it's usually specified from the start of the key travel, so lower numbers.

monochromatic 8y ago

https://danluu.com/keyboard-latency/ https://danluu.com/keyboard-latency/

userbinator 8y ago
Unfortunate lack of PS/2 keyboards in those tests, but the other article linked from there (and discussed here before): https://danluu.com/input-lag/ https://danluu.com/input-lag/ ...shows that the keyboard latency is actually a significant part of input lag.