midi-translator

MIDI Message Translator

Based on status code description

---

Installation

npm install midi-translator

Usage

import MidiTranslator, {MIDI_STATUS} from "midi-translator";

function noteOn(note, velocity){}      
function noteOff(note){}

     
function onMidiMessage(message){
    const msg = midiTranslator.translate(message.data);
    if(msg.status === MIDI_STATUS.NOTE_ON){
        msg.velocity 
            ? noteOn(msg.note, msg.velocity)
            : noteOff(msg.note)
    }
}

if(!navigator.requestMIDIAccess) return;

navigator.requestMIDIAccess().then((midiAccess) => {
    Array.from(midiAccess.inputs).forEach(([id, input]) => 
        input.onmidimessage = onInputMessage
    )
})

Message object shape

NOTE ON

{
    status: 'NOTE_ON',
    channel: 2,
    note: 55,
    velocity: 80,
    original: [ 145, 55, 80 ],
    id: 'CH:2-N_ON:55'
}

NOTE OFF

{
    status: 'NOTE_OFF',
    channel: 8,
    note: 10,
    velocity: 15,
    original: [ 135, 10, 15 ],
    id: 'CH:8-N_OFF:10'
}

POLYPHONIC AFTERTOUCH

 {
    status: 'POLYPHONIC_AFTER_TOUCHE',
    channel: 4,
    note: 22,
    pressure: 100,
    original: [ 163, 22, 100 ],
    id: 'CH:4-PA:22'
}

CONTROL - MODE CHANGE - CC

{
    status: 'CONTROL_CHANGE_CC',
    channel: 5,
    controller: 22,
    value: 100,
    min: false,
    max: false,
    increment: 36,
    decrement: 0,
    original: [ 180, 22, 100 ],
    id: 'CH:5-CC:22'
}

PROGRAM CHANGE

{
    status: 'PROGRAM_CHANGE',
    channel: 6,
    program: 55,
    original: [ 197, 55, 100 ],
    id: 'CH:6-PC'
}

CHANNEL AFTERTOUCH

 {
    status: 'CHANNEL_AFTER_TOUCHE',
    channel: 5,
    pressure: 55,
    original: [ 212, 55, 100 ],
    id: 'CH:5-CA'
}

PITCH WHEEL RANGE

{
    status: 'PITCH_WHEEL_RANGE',
    channel: 3,
    value: 88,
    lsb: 88,
    msb: 10,
    original: [ 226, 88, 10 ],
    id: 'CH:3-PW'
}

There are more different message object shapes depending on the message status code. Above are listed only the most common one. But there exist more specific system codes. Bellow full list of midi status.

MIDI Status

import {MIDI_STATUS} from "midi-translator";

//shape
const MIDI_STATUS = {
    NOTE_ON : "NOTE_ON",
    NOTE_OFF : "NOTE_OFF",
    POLYPHONIC_AFTER_TOUCHE: "POLYPHONIC_AFTER_TOUCHE",
    CONTROL_CHANGE: "CONTROL_CHANGE_CC",
    PROGRAM_CHANGE: "PROGRAM_CHANGE",
    CHANNEL_AFTER_TOUCHE : "CHANNEL_AFTER_TOUCHE",
    PITCH_WHEEL_RANGE: "PITCH_WHEEL_RANGE",
    SYSTEM_EXCLUSIVE: "SYSTEM_EXCLUSIVE",
    SYSTEM_COMMON : "SYSTEM_COMMON",
    SONG_POSITION_POINTER: "SONG_POSITION_POINTER",
    SONG_SELECT: "SONG_SELECT",
    TIMING_CLOCK: "TIMING_CLOCK",
    START: "START",
    CONTINUE: "CONTINUE",
    STOP: "STOP",
    ACTIVE_SENSING: "ACTIVE_SENSING",
    RESET: "SYSTEM_RESET",
    TUNE_REQUEST: "TUNE_REQUEST",
    END_SYSEX: "END_SYSEX",
    OTHER: "OTHER"
}