dspjs
Version:
DSP.js is a comprehensive digital signal processing library for javascript
85 lines (70 loc) • 2.67 kB
HTML
<html>
<head>
<script language="javascript" src="js/processing.js"></script>
<script language="javascript" src="js/init.js"></script>
<script language="javascript" src="../dsp.js"></script>
</head>
<body>
<style>
body { background: black; margin:0; padding:0;}
</style>
<script>
var frameBufferSize = 4096;
var bufferSize = frameBufferSize/2;
var signal = new Float32Array(bufferSize);
var peak = new Float32Array(bufferSize);
var fft = new RFFT(bufferSize, 44100);
function loadedMetaData(event) {
var audio = document.getElementById('input');
audio.mozFrameBufferLength = frameBufferSize;
audio.addEventListener("MozAudioAvailable", audioAvailable, false);
}
function audioAvailable(event) {
// deinterleave and mix down to mono
signal = DSP.getChannel(DSP.MIX, event.frameBuffer);
// perform forward transform
fft.forward(signal);
// calculate peak values
for ( var i = 0; i < bufferSize; i++ ) {
fft.spectrum[i] *= -1 * Math.log((fft.bufferSize/2 - i) * (0.5/fft.bufferSize/2)) * fft.bufferSize; // equalize, attenuates low freqs and boosts highs
if ( peak[i] < fft.spectrum[i] ) {
peak[i] = fft.spectrum[i];
} else {
peak[i] *= 0.99; // peak slowly falls until a new peak is found
}
}
}
</script>
<script target="#fft" type="application/processing">
void setup() {
size(1400, 600);
colorMode(HSB, 360, 100, 100);
strokeWeight(3);
frameRate(60);
//strokeCap(SQUARE);
}
void draw() {
background(0);
//fill(0, 60);
//rect(0, 0, width, height);
for ( int i = 0; i < fft.spectrum.length/2; i += 3 ) {
if (3 * i > width) { break; }
var magnitude = fft.spectrum[i];
// draw magnitudes
stroke((i) % 360, 60, constrain(magnitude * 6, 20, 100));
line(3*i, height, 3*i, height - magnitude * 16);
// draw peak indicators
stroke((i) % 360, 60, constrain(magnitude * 100, 50, 100));
line(3*i, height - peak[i] * 16 - 1, 3*i, height - peak[i] * 16);
}
/*
if (frameCount % 100 == 0 ) {
println(FRAME_RATE);
}
*/
}
</script>
<audio id="input" src="audio/corban-peddle.ogg" controls="true" onloadedmetadata="loadedMetaData(event);"></audio><br />
<div><canvas id="fft"></canvas></div>
</body>
</html>