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Fix: Relative/absolute time delay handling in audio #274

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Fix: Relative/absolute time delay handling in audio #274

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46 changes: 17 additions & 29 deletions js/midi/plugin.webaudio.js
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Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,7 @@

midi.programChange = function(channelId, program, delay) {
// if (delay) {
// return setTimeout(function() {
// setTimeout(function() {
// var channel = root.channels[channelId];
// channel.instrument = program;
// }, delay);
Expand All @@ -59,6 +59,9 @@
midi.noteOn = function(channelId, noteId, velocity, delay) {
delay = delay || 0;

/// convert relative delay to absolute delay
var startTime = delay < ctx.currentTime ? delay + ctx.currentTime : delay;

/// check whether the note exists
var channel = root.channels[channelId];
var instrument = channel.instrument;
Expand All @@ -68,11 +71,6 @@
// console.log(MIDI.GM.byId[instrument].id, instrument, channelId);
return;
}

/// convert relative delay to absolute delay
if (delay < ctx.currentTime) {
delay += ctx.currentTime;
}

/// create audio buffer
if (useStreamingBuffer) {
Expand Down Expand Up @@ -101,17 +99,12 @@
source.connect(source.gainNode);
///
if (useStreamingBuffer) {
if (delay) {
return setTimeout(function() {
buffer.currentTime = 0;
buffer.play()
}, delay * 1000);
} else {
setTimeout(function() {
buffer.currentTime = 0;
buffer.play()
}
}, delay * 1000);
} else {
source.start(delay || 0);
source.start(startTime);
}
///
sources[channelId + '' + noteId] = source;
Expand All @@ -122,40 +115,35 @@
midi.noteOff = function(channelId, noteId, delay) {
delay = delay || 0;

/// convert relative delay to absolute delay
var startTime = delay < ctx.currentTime ? delay + ctx.currentTime : delay;

/// check whether the note exists
var channel = root.channels[channelId];
var instrument = channel.instrument;
var bufferId = instrument + '' + noteId;
var buffer = audioBuffers[bufferId];
if (buffer) {
if (delay < ctx.currentTime) {
delay += ctx.currentTime;
}
///
var source = sources[channelId + '' + noteId];
if (source) {
if (source.gainNode) {
// @Miranet: 'the values of 0.2 and 0.3 could of course be used as
// a 'release' parameter for ADSR like time settings.'
// add { 'metadata': { release: 0.3 } } to soundfont files
var gain = source.gainNode.gain;
gain.linearRampToValueAtTime(gain.value, delay);
gain.linearRampToValueAtTime(-1.0, delay + 0.3);
gain.linearRampToValueAtTime(gain.value, startTime);
gain.linearRampToValueAtTime(-1.0, startTime + 0.3);
}
///
if (useStreamingBuffer) {
if (delay) {
setTimeout(function() {
buffer.pause();
}, delay * 1000);
} else {
setTimeout(function() {
buffer.pause();
}
}, delay * 1000);
} else {
if (source.noteOff) {
source.noteOff(delay + 0.5);
source.noteOff(startTime + 0.5);
} else {
source.stop(delay + 0.5);
source.stop(startTime + 0.5);
}
}
///
Expand Down Expand Up @@ -323,4 +311,4 @@
return new (window.AudioContext || window.webkitAudioContext)();
};
})();
})(MIDI);
})(MIDI);