3 ms·
There’s an iPhone app called Is It Snappy that records in slow motion and makes it pretty easy. I think the camera maxes out at 240 fps so it’s not perfect but
by snazz 3y ago
There’s an iPhone app called Is It Snappy that records in slow motion and makes it pretty easy. I think the camera maxes out at 240 fps so it’s not perfect but it lets you measure true end-to-end latency.
- dan-robertson 3y agoYeah this is the easiest way to get started. You probably want a low travel keyboard and ideally a low-latency-variance one to make it easier to find the start. It can be tricky to find where the update ends too because you usually see several frames of lcd switching. The more advanced version is putting together a microcontroller which acts as a usb keyboard pressing a key, then backspace, then the key again, and uses a light sensor aimed at the right part of the screen to detect rendering in a repeatable way (slightly different fonts/ positions might change when it triggers but that’s likely on the order of a few ms tops, much less than the variance from frame boundaries).
- HideousKojima 3y agoOr you could just have an led on your microcontroller that sends the keypress, and catch both the monitor and the led with the high speed camera
- snvzz 3y agoOr use an USB HDMI capture card, and not involve a monitor in the process.
- dan-robertson 3y agoThe goal with a hardware device is partly avoiding having to label the begin/end times on a bunch of videos.