generic-midi-controller

A common interface for handling different MIDI controller input/output devices using the Web MIDI API.

Usage

controller = GenericMIDI(input, output)

Creates a Controller instance. Input/output handling is customizable using the input and output functions:

input

An object where each property contains an array of functions for determining updated values on receiving MIDI input messages. Optional.

const controller = GenericMIDI({
  buttons: [
    msg => msg[1] === 72 ? msg[2] : null,
    msg => msg[1] === 73 ? msg[2] : null,
    msg => msg[1] === 74 ? msg[2] : null,
    msg => msg[1] === 75 ? msg[2] : null
  ]
})

The above controller listens to events for value changes on inputs 72 through 75. Note that null is returned when a value should not be updated.

Once set up as such, the following should be possible:

controller.setInput(midiInput)

// ...after receiving some MIDI messages:
controller.inputs.buttons[0] // 127
controller.inputs.buttons[1] // 24
controller.inputs.buttons[2] // 0
controller.inputs.buttons[3] // 38

output

An object where each property contains an array of functions for triggering output MIDI messages using send. Optional.

const controller = GenericMIDI(null, {
  buttons: [
    (value, send) => send([152, 72, value]),
    (value, send) => send([152, 73, value]),
    (value, send) => send([152, 74, value]),
    (value, send) => send([152, 75, value])
  ]
})

Once set up as such, the following should be possible:

controller.setOutput(midiOutput)

controller.outputs.buttons[0] = 127 // sends "127" to button 0
controller.outputs.buttons[1] = 24  // sends "24" to button 1
controller.outputs.buttons[2] = 0   // sends "0" to button 2
controller.outputs.buttons[3] = 38  // sends "38" to button 3

controller.setInput(input)

Sets the input MIDI device.

controller.setOutput(output)

Sets the output MIDI device.

navigator.requestMIDIAccess({
  sysex: true
}).then(function (midi) {
  var outputs = []
  var inputs = []

  for (var input of midi.inputs.values()) {
    inputs.push(input)
  }
  for (var output of midi.outputs.values()) {
    outputs.push(output)
  }

  controller.setInput(inputs[0])
  controller.setOutput(outputs[0])
})

controller.on('input', fn(group, i, value))

Fired whenever an input message is received and handled:

controller.on('input', (group, id, value) => {
  console.log(`${group} #${id} has been set to ${value}`)
})

controller.on('output', fn(group, i, value))

Fired whenever an output update is triggered:

controller.on('input', (group, id, value) => {
  console.log(`${group} #${id} has been set to ${value}`)
})

See Also

• midi-controller

License

MIT. See LICENSE.md for details.