Created
May 5, 2013 14:51
-
-
Save huydx/5521025 to your computer and use it in GitHub Desktop.
visualizer.js
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
(function(){ | |
window.onload = init; | |
function init() { | |
var context = new webkitAudioContext(); | |
var audiobuffer; | |
var sourceNode; | |
var analyzer; | |
window.javascriptnode = null; | |
var ctx = document.getElementById("canvas").getContext("2d"); | |
var gradient = ctx.createLinearGradient(0,0,0,130); | |
gradient.addColorStop(1,'#000000'); | |
gradient.addColorStop(0.75,'#ff0000'); | |
gradient.addColorStop(0.25,'#ffff00'); | |
gradient.addColorStop(0,'#ffffff'); | |
setupAudioNodes(); | |
loadsound("tonetest.mp3"); | |
function setupAudioNodes() { | |
window.javascriptnode = context.createJavaScriptNode(2048, 1, 1); | |
window.javascriptnode.connect(context.destination); | |
analyzer = context.createAnalyser(); | |
analyzer.smoothingTimeConstant = 0.3; | |
analyzer.fftSize = 1024; | |
sourceNode = context.createBufferSource(); | |
splitter = context.createChannelSplitter(); | |
splitter.connect(analyzer, 0, 0); | |
sourceNode.connect(splitter); | |
analyzer.connect(window.javascriptnode); | |
sourceNode.connect(context.destination); | |
} | |
function loadsound(source) { | |
var req = new XMLHttpRequest(); | |
req.open('GET', source, true); | |
req.responseType = 'arraybuffer'; | |
req.onload = function() { | |
context.decodeAudioData(req.response, function(buffer){ | |
playSound(buffer); | |
}, onError); | |
} | |
req.send(); | |
} | |
function playSound(buffer){ | |
sourceNode.buffer = buffer; | |
sourceNode.noteOn(0); | |
} | |
var onError = function(e) { | |
console.log(e); | |
} | |
function getAverageVolume(array) { | |
var vals = 0; | |
var length = array.length; | |
for (var i=0; i<length; i++) { | |
vals += array[i]; | |
} | |
return (vals / length) | |
} | |
window.javascriptnode.onaudioprocess = function() { | |
var array = new Uint8Array(analyzer.frequencyBinCount); | |
analyzer.getByteFrequencyData(array); | |
var average = getAverageVolume(array); | |
ctx.clearRect(0, 0, 60, 130); | |
ctx.fillStyle=gradient; | |
ctx.fillRect(0,130-average,25,130); | |
} | |
} | |
})(); | |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment