semi-realtime-magenta.js

const Docker = require('dockerode');
const fs = require('fs');
const midi = require('midi');
const parseMidi = require('midi-file').parseMidi;

const docker = new Docker();
const midiOutput = new midi.output();
const midiInput = new midi.input();

function noteNumberToNoteName(noteNumber) {
    return ["C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B" ][noteNumber % 12];
}

midiOutput.openPort(0);
midiInput.openPort(1);

midiInput.on('message', function(deltaTime, message) {
    if (message[0] == 144 && message[2] != 0) {
        console.log("Input: " + noteNumberToNoteName(message[1]));

        const p = Promise.resolve();
        p.then(() => {
            /*
                return docker.pull('tensorflow/magenta');
        }).then(() => {
                 */
            return docker.run('tensorflow/magenta', [
                'melody_rnn_generate',
                '--config=lookback_rnn',
                '--bundle_file=/magenta-models/lookback_rnn.mag',
                '--output_dir=/magenta-data/lookback_rnn/generated',
                '--num_outputs=1',
                '--num_steps=64',
                '--primer_melody=[' + message[1] + ']'
            ], null, {
                Binds: [ "/tmp/magenta:/magenta-data:rw" ]
            });
        }).then(() => {
            noteQueue.splice(0, noteQueue.length);

            fs.readdir("/tmp/magenta/lookback_rnn/generated", (err, list) => {
                list.forEach((file) => {
                    const midiFile = parseMidi(fs.readFileSync("/tmp/magenta/lookback_rnn/generated/" + file));

                    output = "";
                    midiFile.tracks[1].forEach((packet) => {
                        if (packet.type == "noteOn") {
                            noteQueue.push(packet.noteNumber);
                            output += noteNumberToNoteName(packet.noteNumber) + " ";
                        }
                    });
                    console.log("Output: " + output);

                    fs.unlinkSync("/tmp/magenta/lookback_rnn/generated/" + file);
                });
            });
        });
    }
});

const noteQueue = [ ];
setInterval(() => {
    if (noteQueue.length) {
        const noteNumber = noteQueue.shift();

        // NOTE ON
        midiOutput.sendMessage([ 144, noteNumber, 127 ]);

        // NOTE OFF
        setTimeout((noteNumber) => {
            midiOutput.sendMessage([ 128, noteNumber, 0 ]);
        }, 60 / 135 * 1000, noteNumber)
    }
}, 60 / 135 * 1000);