music21j-port/src/ext/midijs/js/plugin.audiotag.js

A toolkit for computer-aided musicology, Javascript version

/*
	----------------------------------------------------------------------
	AudioTag <audio> - OGG or MPEG Soundbank
	----------------------------------------------------------------------
	http://dev.w3.org/html5/spec/Overview.html#the-audio-element
	----------------------------------------------------------------------
*/
import { DEBUG } from './debug.js';
import { channels, GM, keyToNote, noteToKey } from './gm.js';

// information to share with loader...
export const shared_root_info = {};

const volumes = []; // floating point
for (let vid = 0; vid < 16; vid ++) {
	volumes[vid] = 127;
}


let buffer_nid = -1; // current channel
const notesOn = []; // instrumentId + noteId that is currently playing in each 'channel', for routing noteOff/chordOff calls
const notes = {}; // the piano keys

const audioBuffers = []; // the audio channels
for (let nid = 0; nid < 12; nid ++) {
	audioBuffers[nid] = new Audio();
}

export const playChannel = (channel, in_note) => {
	if (!channels[channel]) {
		return;
	}
	const instrument = channels[channel].program;
	const instrumentId = GM.byId[instrument].id;
	const note = notes[in_note];
	if (note) {
		const instrumentNoteId = instrumentId + '' + note.id;
		const nid = (buffer_nid + 1) % audioBuffers.length;
		const audio = audioBuffers[nid];
		notesOn[nid] = instrumentNoteId;
		if (!shared_root_info.Soundfont[instrumentId]) {
			if (DEBUG) {
				console.log('404', instrumentId);
			}
			return;
		}
		audio.src = shared_root_info.Soundfont[instrumentId][note.id];
		audio.volume = volumes[channel] / 127;
		audio.play();
		buffer_nid = nid;
	}
};

export const stopChannel = (channel, in_note) => {
	if (!channels[channel]) {
		return;
	}
	const instrument = channels[channel].program;
	const instrumentId = GM.byId[instrument].id;
	const note = notes[in_note];
	if (note) {
		const instrumentNoteId = instrumentId + '' + note.id;
		for (let i = 0, len = audioBuffers.length; i < len; i++) {
			const nid = (i + buffer_nid + 1) % len;
			const cId = notesOn[nid];
			if (cId && cId === instrumentNoteId) {
				audioBuffers[nid].pause();
				notesOn[nid] = null;
				return;
			}
		}
	}
};

// midi.audioBuffers = audioBuffers;
export const send = (data, delay) => { };
export const setController = (channel, type, value, delay) => { };
export const setVolume = (channel, n) => {
	volumes[channel] = n;
};

export const programChange = (channel, program) => {
	channels[channel].instrument = program;
};

export const pitchBend = (channel, program, delay) => { };

export const noteOn = (channel, note, velocity, delay) => {
	const id = noteToKey[note];
	if (!notes[id]) {
		return;
	}
	if (delay) {
		return setTimeout(() => {
			volumes[channel] = velocity;
			playChannel(channel, id);
		}, delay * 1000);
	} else {
		volumes[channel] = velocity;
		playChannel(channel, id);
	}
};

export const noteOff = (channel, note, delay) => {
	// MSC: Commented out in MudCube version...
	//      I see why!  clips all the notes!

	// const id = noteToKey[note];
	// if (!notes[id]) {
	// 	return;
	// }
	// if (delay) {
	// 	return setTimeout(function() {
	// 		stopChannel(channel, id);
	// 	}, delay * 1000)
	// } else {
	// 	stopChannel(channel, id);
	// }
};

export const chordOn = (channel, chord, velocity, delay) => {
	for (let idx = 0; idx < chord.length; idx ++) {
		const n = chord[idx];
		const id = noteToKey[n];
		if (!notes[id]) {
			continue;
		}
		if (delay) {
			return setTimeout(() => {
				playChannel(channel, id);
			}, delay * 1000);
		} else {
			playChannel(channel, id);
		}
	}
};

export const chordOff = (channel, chord, delay) => {
	for (let idx = 0; idx < chord.length; idx ++) {
		const n = chord[idx];
		const id = noteToKey[n];
		if (!notes[id]) {
			continue;
		}
		if (delay) {
			return setTimeout(() => {
				stopChannel(channel, id);
			}, delay * 1000);
		} else {
			stopChannel(channel, id);
		}
	}
};

export const stopAllNotes = () => {
	for (let nid = 0, length = audioBuffers.length; nid < length; nid++) {
		audioBuffers[nid].pause();
	}
};

export const connect = opts => {
	for (const key in keyToNote) {
		notes[key] = {id: key};
	}
	//
	opts.onsuccess && opts.onsuccess();
};