MIDI.js/js/MIDI/Player.js
2012-10-09 22:59:04 -07:00

282 lines
6.8 KiB
JavaScript

/*
MIDI.Player : 0.3
-------------------------------------
https://github.com/mudcube/MIDI.js
-------------------------------------
requires jasmid
*/
if (typeof (MIDI) === "undefined") var MIDI = {};
if (typeof (MIDI.Player) === "undefined") MIDI.Player = {};
(function() { "use strict";
var root = MIDI.Player;
root.callback = undefined; // your custom callback goes here!
root.currentTime = 0;
root.endTime = 0;
root.restart = 0;
root.playing = false;
root.timeWarp = 1;
//
root.start =
root.resume = function () {
if (root.currentTime < -1) root.currentTime = -1;
startAudio(root.currentTime);
};
root.pause = function () {
var tmp = root.restart;
stopAudio();
root.restart = tmp;
};
root.stop = function () {
stopAudio();
root.restart = 0;
root.currentTime = 0;
};
root.addListener = function(callback) {
onMidiEvent = callback;
};
root.removeListener = function() {
onMidiEvent = undefined;
};
root.clearAnimation = function() {
if (root.interval) {
window.clearInterval(root.interval);
}
};
root.setAnimation = function(config) {
var callback = (typeof(config) === "function") ? config : config.callback;
var interval = config.interval || 30;
var currentTime = 0;
var tOurTime = 0;
var tTheirTime = 0;
//
root.clearAnimation();
root.interval = window.setInterval(function () {
if (root.endTime === 0) return;
if (root.playing) {
currentTime = (tTheirTime === root.currentTime) ? tOurTime - (new Date).getTime() : 0;
if (root.currentTime === 0) {
currentTime = 0;
} else {
currentTime = root.currentTime - currentTime;
}
if (tTheirTime !== root.currentTime) {
tOurTime = (new Date).getTime();
tTheirTime = root.currentTime;
}
} else { // paused
currentTime = root.currentTime;
}
var endTime = root.endTime;
var percent = currentTime / endTime;
var total = currentTime / 1000;
var minutes = total / 60;
var seconds = total - (minutes * 60);
var t1 = minutes * 60 + seconds;
var t2 = (endTime / 1000);
if (t2 - t1 < -1) return;
callback({
now: t1,
end: t2,
events: noteRegistrar
});
}, interval);
};
// helpers
root.loadMidiFile = function() { // reads midi into javascript array of events
root.replayer = new Replayer(MidiFile(root.currentData), root.timeWarp);
root.data = root.replayer.getData();
root.endTime = getLength();
};
root.loadFile = function (file, callback) {
root.stop();
if (file.indexOf("base64,") !== -1) {
var data = window.atob(file.split(",")[1]);
root.currentData = data;
root.loadMidiFile();
if (callback) callback(data);
return;
}
///
var title = file.split(" - ")[1] || file;
document.getElementById("playback-title").innerHTML = title.replace(".mid","");
///
var fetch = new XMLHttpRequest();
fetch.open('GET', file);
fetch.overrideMimeType("text/plain; charset=x-user-defined");
fetch.onreadystatechange = function () {
if (this.readyState === 4 && this.status === 200) {
var t = this.responseText || "";
var ff = [];
var mx = t.length;
var scc = String.fromCharCode;
for (var z = 0; z < mx; z++) {
ff[z] = scc(t.charCodeAt(z) & 255);
}
var data = ff.join("");
root.currentData = data;
root.loadMidiFile();
if (callback) callback(data);
}
};
fetch.send();
};
// Playing the audio
var eventQueue = []; // hold events to be triggered
var queuedTime; //
var startTime = 0; // to measure time elapse
var noteRegistrar = {}; // get event for requested note
var onMidiEvent = undefined; // listener callback
var scheduleTracking = function (channel, note, currentTime, offset, message, velocity) {
var interval = window.setTimeout(function () {
var data = {
channel: channel,
note: note,
now: currentTime,
end: root.endTime,
message: message,
velocity: velocity
};
//
if (message === 128) {
delete noteRegistrar[note];
} else {
noteRegistrar[note] = data;
}
if (onMidiEvent) {
onMidiEvent(data);
}
root.currentTime = currentTime;
if (root.currentTime === queuedTime && queuedTime < root.endTime) { // grab next sequence
startAudio(queuedTime, true);
}
}, currentTime - offset);
return interval;
};
var getContext = function() {
if (MIDI.lang === 'WebAudioAPI') {
return MIDI.Player.ctx;
} else if (!root.ctx) {
root.ctx = { currentTime: 0 };
}
return root.ctx;
};
var getLength = function() {
var data = root.data;
var length = data.length;
var totalTime = 0.5;
for (var n = 0; n < length; n++) {
totalTime += data[n][1];
}
return totalTime;
};
var startAudio = function (currentTime, fromCache) {
if (!root.replayer) return;
if (!fromCache) {
if (typeof (currentTime) === "undefined") currentTime = root.restart;
if (root.playing) stopAudio();
root.playing = true;
root.data = root.replayer.getData();
root.endTime = getLength();
}
var note;
var offset = 0;
var messages = 0;
var data = root.data;
var ctx = getContext();
var length = data.length;
//
queuedTime = 0.5;
startTime = ctx.currentTime;
//
for (var n = 0; n < length && messages < 100; n++) {
queuedTime += data[n][1];
if (queuedTime <= currentTime) {
offset = queuedTime;
continue;
}
currentTime = queuedTime - offset;
var event = data[n][0].event;
if (event.type !== "channel") continue;
var channel = event.channel;
switch (event.subtype) {
case 'noteOn':
if (MIDI.channels[channel].mute) break;
note = event.noteNumber - (root.MIDIOffset || 0);
eventQueue.push({
event: event,
source: MIDI.noteOn(channel, event.noteNumber, event.velocity, currentTime / 1000 + ctx.currentTime),
interval: scheduleTracking(channel, note, queuedTime, offset, 144, event.velocity)
});
messages ++;
break;
case 'noteOff':
if (MIDI.channels[channel].mute) break;
note = event.noteNumber - (root.MIDIOffset || 0);
eventQueue.push({
event: event,
source: MIDI.noteOff(channel, event.noteNumber, currentTime / 1000 + ctx.currentTime),
interval: scheduleTracking(channel, note, queuedTime, offset - 10, 128)
});
break;
default:
break;
}
}
};
var stopAudio = function () {
var ctx = getContext();
root.playing = false;
root.restart += (ctx.currentTime - startTime) * 1000;
// stop the audio, and intervals
while (eventQueue.length) {
var o = eventQueue.pop();
window.clearInterval(o.interval);
if (!o.source) continue; // is not webaudio
if (typeof(o.source) === "number") {
window.clearTimeout(o.source);
} else { // webaudio
var source = o.source;
source.disconnect(0);
source.noteOff(0);
}
}
// run callback to cancel any notes still playing
for (var key in noteRegistrar) {
var o = noteRegistrar[key]
if (noteRegistrar[key].message === 144 && onMidiEvent) {
onMidiEvent({
channel: o.channel,
note: o.note,
now: o.now,
end: o.end,
message: 128,
velocity: o.velocity
});
}
}
// reset noteRegistrar
noteRegistrar = {};
};
})();