I’m writing a class to send 14-bit midi to a digital guitar amp (a Kemper) and running into a latency issues when using custom Event types in patterns. Here’s an example of one of the types, used for switching built-in effects on the pedalboard/amplifier:
Event.addEventType(\kemperFxType,{
if(~kemperMIDI == -1,{
"no KemperMIDI instance specified ".error;
},{
var kMIDI = ~kemperMIDI; // an instance of KemperMIDI, basically MIDIOut with a coat of paint
var page = kMIDI.prPageCheck( ~addrPg ); // can be a symbol, returns integer
var fxBits = KemperMIDI.fxKeys[ ~fxKey ]; // can be a symbol, returns integer
var chn = kMIDI.chan - 1 + 0xB0;
var onOff = case
{ ~switchOn == false }{ 0x00 }
{ ~switchOn == true }{ 0x01 }
{ "switchOn must be a boolean".error };
var pkt = [
// these bits assign the effect to the correct effect slot
chn, 0x63, page,
chn, 0x62, 0x00,
chn, 0x06, fxBits[0],
chn, 0x26, fxBits[1],
// the effects are off by default, must turn them on...
chn, 0x63, page,
chn, 0x62, 0x03,
chn, 0x06, 0x00,
chn, 0x26, onOff,
];
thisThread.clock.sched(~latency, kMIDI.midiOut.sysex( pkt.as( Int8Array ) ) )
});
},(
kemperMIDI: -1,
addrPg: 50,
fxKey: 'empty',
switchOn: true,
))
This “works,” but the timing is very inconsistent - if I’m sending a whole buncha MIDI messages at once (the amp has 8 effects slots, I also have an Event for sending 14-bit control messages, sometimes there’s a lot of traffic…) the switching of effects can be delayed by several seconds, while the control messages don’t seem to be interrupted.
I feel like I’m missing something about 1) event scheduling 2) MIDI latency / bandwidth limitations and/or 3) something else I haven’t considered? I guess hardware latency could be an issue as well…I’ll admit I don’t know so much about MIDI and timing, so any/all tips are appreciated - thanks in advance!
(running on macOS 13.6, for what it’s worth)