Created
May 1, 2012 20:50
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audiolib.js fft
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| (function () { | |
| var device, | |
| osc1, | |
| lfo1, | |
| lfo2, | |
| lfo3, | |
| lfo4, | |
| fft, | |
| fps = 30, | |
| channelCount = 2, | |
| width, | |
| height, | |
| context, | |
| playing = false; | |
| function audioCallback (buffer, channels) { | |
| if (!playing) return; | |
| var i, sample, bufferLength = buffer.length; | |
| for (i = 0; i < bufferLength; i += channels) { | |
| lfo1.generate(); | |
| lfo2.generate(); | |
| lfo3.generate(); | |
| lfo4.generate(); | |
| lfo2.fm = lfo1.getMix(); | |
| lfo3.fm = lfo2.getMix(); | |
| lfo4.fm = lfo3.getMix(); | |
| osc1.fm = lfo4.getMix(); | |
| osc1.generate(); | |
| sample = osc1.getMix(); | |
| fft.pushSample(sample); | |
| for (n = 0; n < channelCount; n++){ | |
| buffer[i + n] = sample; | |
| } | |
| } | |
| } | |
| window.addEventListener('load', function() { | |
| var canvas, button; | |
| // set up audio stuff | |
| device = audioLib.AudioDevice(audioCallback, channelCount); | |
| osc1 = audioLib.Oscillator(device.sampleRate, 600); | |
| osc1.waveShape = 'triangle'; | |
| lfo1 = audioLib.Oscillator(device.sampleRate, 0.1); | |
| lfo2 = audioLib.Oscillator(device.sampleRate, 10.3); | |
| lfo3 = audioLib.Oscillator(device.sampleRate, 0.7); | |
| lfo4 = audioLib.Oscillator(device.sampleRate, 6.2); | |
| fft = audioLib.FFT(device.sampleRate, 4096); | |
| // set up UI display stuff | |
| canvas = document.getElementById('canvas'); | |
| context = canvas.getContext('2d'); | |
| width = canvas.width; | |
| height = canvas.height; | |
| gradient = context.createLinearGradient(0, 0, 0, height / 2); | |
| gradient.addColorStop(0, "#ff0000"); | |
| gradient.addColorStop(1, "#0000ff"); | |
| context.fillStyle = gradient; | |
| context.lineWidth = 1; | |
| button = document.getElementById('playButton'); | |
| button.onclick = function () { | |
| playing = !playing; | |
| button.innerHTML = playing ? 'pause' : 'play'; | |
| }; | |
| }); | |
| function drawFFT () { | |
| var length, count; | |
| length = fft.spectrum.length / 8; | |
| context.clearRect(0, 0, width, height); | |
| context.beginPath(); | |
| context.moveTo(0, height); | |
| for (count = 0; count < length; count++) { | |
| context.lineTo(count / length * width, | |
| fft.spectrum[count] * -height * 2 + height); | |
| } | |
| context.moveTo(width,0); | |
| context.closePath(); | |
| context.fill(); | |
| context.stroke(); | |
| } | |
| Sink.doInterval(function(){ | |
| drawFFT(); | |
| }, 1000/fps); | |
| })(); |
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <title>audiolib.js FFT demo</title> | |
| <script type="text/javascript" src="audiolib.min.js"></script> | |
| <script type="text/javascript" src="fft.js"></script> | |
| </head> | |
| <body> | |
| <p><button id="playButton">play</button></p> | |
| <canvas id="canvas" width="600" height="200" style="background: #eee;"></canvas> | |
| </body> | |
| </html> |
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