Midi Latency in class I am developing for an APC Mini


I am working on a class for my APC Mini device, and I’ve gotten the basics of it working - , I’m able to get lights blinking, read from the faders, etc. You can see the code here: https://gist.github.com/john-d-murphy/45ea005836aae78185e1ea04465402b6

What I’ve noticed, though, is that when either addressing the device directly or handling the device via the callbacks, that there is a noticeable latency between when I press a button and when I see the noteout message trigger the pad light. This is basically unusable for a musical setting, so I wanted to check with the group to see how I could start debugging this.

For context, I am on a Gentoo Linux machine, and I am running Supercollider through Jack using ALSA. If my code is fine, there’s likely an issue with how I have my machine set up, and I’ll need to go down that rabbit hole.

First thing to check is: http://doc.sccode.org/Classes/MIDIOut.html#-latency


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That’s it. Didn’t realize the server latency would have an effect on the midi output latency, but in retrospect that makes sense. Dropped the latency on the server, made the midiout latency 0, and now it behaves as expected.