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AudioContext.html
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AudioContext.html
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0" />
<meta name="apple-mobile-web-app-capable" content="yes" />
<meta name="apple-mobile-web-app-status-bar-style" content="black" />
<meta content="telephone=no" name="format-detection" />
<title>wave</title>
<style type="text/css">
* {
margin: 0;
padding: 0;
}
body {
overflow: hidden;
font: 12px/1.5 tahoma,arial,sans-serif;
}
canvas {
background-color: #333;
}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<script type="text/javascript">
window.onload = function() {
var canvas = document.getElementById('canvas');
context = canvas.getContext("2d"),
width = canvas.width = window.innerWidth,
height = canvas.height = window.innerHeight;
K = 2;
F = 2;
Noise = 0.01;
ALPHA = 0.8;
ALPHA2 = 0.01;
update();
var phase = 0;
var speed = 0.15;
function update() {
phase = (phase + speed) % (Math.PI * 64)
context.clearRect(0, 0, width, height);
drawLine(1, "rgba(255,255,0,1)", 5);
drawLine(2, "rgba(65,159,73,0.9)",4);
drawLine(-2, "rgba(212,50,61,0.9))",3);
drawLine(4, "rgba(111,179,234,0.9)",2);
drawLine(-6, "rgba(249,242,244,0.7)",1);
requestAnimationFrame(update);
}
function drawLine(attenuation, lineColor, lineWidth) {
context.moveTo(0, 0);
context.beginPath();
context.strokeStyle = lineColor;
context.lineWidth = lineWidth || 1;
var x, y;
for (var i = -K; i <= K; i += 0.01) {
x = width * ((i + K) / (K * 2));
y = height / 2 + Noise * (1 / attenuation) * ((height / 2) * (Math.sin(F * i - phase))) * globalAttenuationFn(i);
context.lineTo(x, y);
}
context.stroke();
}
function globalAttenuationFn(x) {
return Math.pow(K * 4 / (K * 4 + Math.pow(x, 4)), K * 2);
}
}
// create the audio context (chrome only for now)
if (!window.AudioContext) {
if (!window.webkitAudioContext) {
alert('no audiocontext found');
}
window.AudioContext = window.webkitAudioContext;
}
var contextA = new AudioContext();
var audioBuffer;
var sourceNode;
var splitter;
var analyser;
var javascriptNode;
// get the context from the canvas to draw on
// create a gradient for the fill. Note the strange
// offset, since the gradient is calculated based on
// the canvas, not the specific element we draw
// load the sound
setupAudioNodes();
loadSound('demo.mp3');
function setupAudioNodes() {
// setup a javascript node
javascriptNode = contextA.createScriptProcessor(2048, 1, 1);
// connect to destination, else it isn't called
javascriptNode.connect(contextA.destination);
// setup a analyzer
analyser = contextA.createAnalyser();
analyser.smoothingTimeConstant = 0.3;
analyser.fftSize = 1024;
analyser2 = contextA.createAnalyser();
analyser2.smoothingTimeConstant = 0.0;
analyser2.fftSize = 1024;
// create a buffer source node
sourceNode = contextA.createBufferSource();
splitter = contextA.createChannelSplitter();
// connect the source to the analyser and the splitter
sourceNode.connect(splitter);
splitter.connect(analyser, 0, 0);
analyser.connect(javascriptNode);
sourceNode.connect(contextA.destination);
}
// load the specified sound
function loadSound(url) {
var request = new XMLHttpRequest();
request.open('GET', url, true);
request.responseType = 'arraybuffer';
var oAudio = document.getElementById('myaudio');
// When loaded decode the data
request.onload = function() {
// decode the data
contextA.decodeAudioData(request.response, function(buffer) {
alert("加载完毕")
// when the audio is decoded play the sound
playSound(buffer);
}, onError);
}
request.send();
}
function playSound(buffer) {
document.getElementById('canvas').addEventListener("click", function(){
sourceNode.buffer = buffer;
sourceNode.start(0);
})
// sourceNode.play();
}
// log if an error occurs
function onError(e) {
console.log(e);
}
// when the javascript node is called
// we use information from the analyzer node
// to draw the volume
var isLoadingTextShowing = true;
var loaded = 0; //声音文件未加载完成;
javascriptNode.onaudioprocess = function () {
// get the average for the first channel
var array = new Uint8Array(analyser.frequencyBinCount);
analyser.getByteFrequencyData(array);
var average = getAverageVolume(array);
if (average > 0 || loaded) { //表示声音文件加载完成
loaded = 1;
changeNoise(average);
changeFrequence(average);
if (isLoadingTextShowing) {
isLoadingTextShowing = false;
document.getElementById('hint').style.display = 'none';
}
}
}
var id;
function changeNoise(value) {
var now = Noise;
Noise = ALPHA * now + (1 - ALPHA) * (value / 100);
}
function changeFrequence(value) {
F = 2 + (value / 100) * 3;
}
function getAverageVolume(array) {
var values = 0;
var average;
var length = array.length;
// get all the frequency amplitudes
for (var i = 0; i < length; i++) {
values += array[i];
}
average = values / length;
return average;
}
</script>
</body>
</html>