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Comment by tsenkov | Hacker News Reader

I meant I know what latency is as a notion, just haven't measured it and I don't know how-to.

I feel a bit lame for misleading you in writing this whole thing. Sorry. :(

Well - here is how - record with a camera your keypresses mouse-clicks and at the same time record your screen, and what comes out from your speakers.

Then with some AV editing software, you can mark the time you've pressed the keyboard/mouse click, and when the sound came out.

Awesome! Now lets see how we make that a CI test...hm... :D

Really? Is this the way? When you asked me, I started thinking - maybe the latency of the keyboard all the way up to my code is known... in some spec. As well as the latency after. As a matter of fact, I don't have any control of anything before and after, so there should only be something in the pathway under my control, that makes sense to be measured.

I definitely will give this some thought, thanks for asking.

At least in video games, responsiveness is being measured mainly with high-speed cameras ;) - (60fps, e.g. 16ms is good enough sampling rate)

http://www.gamasutra.com/view/feature/3725/measuring_respons...

This by far is most portable, testable and unbiased way of doing it. If you rely on internal measuring then, well.. Actually I don't know how you can do that - for example when the video / audio signal actually leaves is only verifiable with some external equipment... like camera ;)

I would also do something like tap your desk sharply with a pen right before you film the test, and make sure the audio track is aligned with video at that point. I have no idea how accurate A/V syncing is on say a smartphone, but that would be a bummer if that was completely throwing off the test.

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