1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
|
var sampleRate = 44100; /* hard-coded in Flash player */
function AudioPlayer(generator, opts) {
if (!opts) opts = {};
var latency = opts.latency || 1;
var checkInterval = latency * 100 /* in ms */
var audioElement = new Audio();
var webkitAudio = window.AudioContext || window.webkitAudioContext;
var requestStop = false;
if (audioElement.mozSetup) {
audioElement.mozSetup(2, sampleRate); /* channels, sample rate */
var buffer = []; /* data generated but not yet written */
var minBufferLength = latency * 2 * sampleRate; /* refill buffer when there are only this many elements remaining */
var bufferFillLength = Math.floor(latency * sampleRate);
function checkBuffer() {
if (buffer.length) {
var written = audioElement.mozWriteAudio(buffer);
buffer = buffer.slice(written);
}
if (buffer.length < minBufferLength && !generator.finished) {
buffer = buffer.concat(generator.generate(bufferFillLength));
}
if (!requestStop && (!generator.finished || buffer.length)) {
setTimeout(checkBuffer, checkInterval);
}
}
checkBuffer();
return {
'type': 'Firefox Audio',
'stop': function() {
requestStop = true;
}
}
} else if (webkitAudio) {
// Uses Webkit Web Audio API if available
var context = new webkitAudio();
sampleRate = context.sampleRate;
var channelCount = 2;
var bufferSize = 4096*4; // Higher for less gitches, lower for less latency
var node = context.createScriptProcessor(bufferSize, 0, channelCount);
node.onaudioprocess = function(e) { process(e) };
function process(e) {
if (generator.finished) {
node.disconnect();
return;
}
var dataLeft = e.outputBuffer.getChannelData(0);
var dataRight = e.outputBuffer.getChannelData(1);
var generate = generator.generate(bufferSize);
for (var i = 0; i < bufferSize; ++i) {
dataLeft[i] = generate[i*2];
dataRight[i] = generate[i*2+1];
}
}
// start
node.connect(context.destination);
return {
'stop': function() {
// pause
node.disconnect();
requestStop = true;
},
'type': 'Webkit Audio'
}
} else {
// Fall back to creating flash player
var c = document.createElement('div');
c.innerHTML = '<embed type="application/x-shockwave-flash" id="da-swf" src="da.swf" width="8" height="8" allowScriptAccess="always" style="position: fixed; left:-10px;" />';
document.body.appendChild(c);
var swf = document.getElementById('da-swf');
var minBufferDuration = latency * 1000; /* refill buffer when there are only this many ms remaining */
var bufferFillLength = latency * sampleRate;
function write(data) {
var out = new Array(data.length);
for (var i = data.length-1; i != 0; i--) {
out[i] = Math.floor(data[i]*32768);
}
return swf.write(out.join(' '));
}
function checkBuffer() {
if (swf.bufferedDuration() < minBufferDuration) {
write(generator.generate(bufferFillLength));
};
if (!requestStop && !generator.finished) setTimeout(checkBuffer, checkInterval);
}
function checkReady() {
if (swf.write) {
checkBuffer();
} else {
setTimeout(checkReady, 10);
}
}
checkReady();
return {
'stop': function() {
swf.stop();
requestStop = true;
},
'bufferedDuration': function() {
return swf.bufferedDuration();
},
'type': 'Flash Audio'
}
}
}
|
