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<!DOCTYPE html>
<html>
<!--
WebAudio Csound example
Copyright (C) 2017 V Lazzarini
-->
<head>
<title>WebAudio Csound</title>
<style type="text/css">
html, body {
font-family: Monospace;
color: #bf94f7;
background-color: #000055;
}
#console {
font-family: Monospace;
color: #b5b6ff;
background-color: #000000;
font-size: 16px;
width: 805px;
display: flex;
align-items: center;
justify-content: center;
border-style: solid;
padding: 20px 0px;
}
H1 {
font-size: 36px;
}
#playButton {
margin: auto;
font-family: Monospace;
width: 810px;
padding: 10px 0px;
font-size: 24px;
background-color: #b5b6ff;
}
</style>
<script src="js/CsoundObj.js"></script>
<script type="text/javascript">
var random_colour;
// fancy colours
function getRandomColor() {
var letters = '0123456789ABCDEF'.split('');
var color = '#';
for (var i = 0; i < 6; i++) {
color += letters[Math.floor(Math.random() * 16)];
}
return color;
}
// message printout
function display_msg(message) {
var messField = document.getElementById("console")
messField.innerText = message;
random_colour = messField.style.color = getRandomColor();
}
function print_msg(message) {
csound.requestControlChannel("freq", function() {
freq = Math.round(csound.getControlChannel("freq"));
mess = message + " :: " + freq + " Hz";
display_msg(mess);
});
}
function main() {
CsoundObj.initialize().then(() => {
console.log = print_msg;
console.warn = print_msg;
document.getElementById('playButton').addEventListener('click',
click_this);
document.getElementById('playButton').disabled = false;
CsoundObj.CSOUND_AUDIO_CONTEXT.suspend();
csound = new CsoundObj();
csound.compileOrc(document.getElementById('instruments').value);
csound.start();
window.addEventListener("unload", function(e) {
if (csound != null)
csound.destroy();
}, false);
scopeNode = CsoundObj.CSOUND_AUDIO_CONTEXT.createAnalyser();
csound.getNode().connect(scopeNode);
scope = function() {
let ctx = document.getElementById('scope').getContext('2d');
let width = ctx.canvas.width;
let height = ctx.canvas.height;
let timeData = new Uint8Array(scopeNode.frequencyBinCount);
let scaling = height / 256;
let risingEdge = 0;
let edgeThreshold = 5;
scopeNode.getByteTimeDomainData(timeData);
ctx.fillStyle = 'rgba(0, 20, 0, 0.1)';
ctx.fillRect(0, 0, width, height);
ctx.lineWidth = 2;
ctx.strokeStyle = random_colour;
ctx.beginPath();
while (timeData[risingEdge++] - 128 > 0 && risingEdge <= width);
if (risingEdge >= width) risingEdge = 0;
while (timeData[risingEdge++] - 128 < edgeThreshold &&
risingEdge <= width);
if (risingEdge >= width) risingEdge = 0;
for (var x = risingEdge; x < timeData.length &&
x - risingEdge < width; x++)
ctx.lineTo(x - risingEdge, height - timeData[x] * scaling);
ctx.stroke();
requestAnimationFrame(scope);
}
scope();
mags = function() {
let ctx = document.getElementById('mags').getContext('2d');
let width = ctx.canvas.width;
let height = ctx.canvas.height;
let freqData = new Uint8Array(scopeNode.frequencyBinCount);
let scaling = height / 256;
scopeNode.getByteFrequencyData(freqData);
ctx.fillStyle = 'rgba(0, 20, 0, 0.1)';
ctx.fillRect(0, 0, width, height);
ctx.lineWidth = 2;
ctx.strokeStyle = random_colour;
ctx.beginPath();
for (var x = 0; x < width; x++)
ctx.lineTo(x, height - freqData[x] * scaling);
ctx.stroke();
requestAnimationFrame(mags);
}
mags();
});
}
var playing = false;
function click_this() {
if(playing == false) {
CsoundObj.CSOUND_AUDIO_CONTEXT.resume();
document.getElementById('playButton').innerText = "pause";
playing = true;
} else {
CsoundObj.CSOUND_AUDIO_CONTEXT.suspend();
document.getElementById('playButton').innerText = "play";
playing = false;
}
}
</script>
</head>
<body onload="main()">
<h1> Random Generator</h1>
<div id="console">...loading...
</div>
<canvas id='scope' width=400 height=200 style="border:1px solid#000000;">
</canvas>
<canvas id='mags' width=400 height=200 style="border:1px solid#000000;">
</canvas>
<p>
<button id="playButton" disabled>play</button>
</p>
<textarea class="code" id="instruments" hidden>
/* this is the synthesis code
for this example
*/
nchnls=2
0dbfs=1
instr 1
k1 expon p4,p3,p4*0.001
a1 oscili k1,p5
chnset p5, "freq"
outs a1,a1
schedule 1,0.25,0.5,0.3+rnd(0.2),1000+birnd(500)
endin
schedule 1,0,0.5,0.1,500
</textarea>
</body>
</html>
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