【发布时间】：2013-10-24 06:45:40
【问题描述】：
HTML5 中的 createMediaElementSource（绘制 youtube 视频的可视化）。这可能吗？
如果是，你能给我举个例子吗？我只想添加一个传统的youtube播放器，在它下面的频谱/可视化，我在互联网上找到了一个mp3版本。
这是它的音频/mp3 版本，我只是不知道这是否可以与 youtube 视频流一起使用。
<style type="text/css">
div#mp3_player{ width:500px; height:60px; background:#000; padding:5px; margin:50px auto; }
div#mp3_player > div > audio{ width:500px; background:#000; float:left; }
div#mp3_player > canvas{ width:500px; height:30px; background:#002D3C; float:left; }
</style>
<script>
// Create a new instance of an audio object and adjust some of its properties
var audio = new Audio();
audio.src = '613814.mp3';
audio.controls = true;
audio.loop = true;
audio.autoplay = false;
// Establish all variables that your Analyser will use
var canvas, ctx, source, context, analyser, fbc_array, bars, bar_x, bar_width, bar_height;
// Initialize the MP3 player after the page loads all of its HTML into the window
window.addEventListener("load", initMp3Player, false);
function initMp3Player(){
document.getElementById('audio_box').appendChild(audio);
context = new webkitAudioContext(); // AudioContext object instance
analyser = context.createAnalyser(); // AnalyserNode method
canvas = document.getElementById('analyser_render');
ctx = canvas.getContext('2d');
// Re-route audio playback into the processing graph of the AudioContext
source = context.createMediaElementSource(audio);
source.connect(analyser);
analyser.connect(context.destination);
frameLooper();
}
// frameLooper() animates any style of graphics you wish to the audio frequency
// Looping at the default frame rate that the browser provides(approx. 60 FPS)
function frameLooper(){
window.webkitRequestAnimationFrame(frameLooper);
fbc_array = new Uint8Array(analyser.frequencyBinCount);
analyser.getByteFrequencyData(fbc_array);
ctx.clearRect(0, 0, canvas.width, canvas.height); // Clear the canvas
ctx.fillStyle = '#00CCFF'; // Color of the bars
bars = 100;
for (var i = 0; i < bars; i++) {
bar_x = i * 3;
bar_width = 2;
bar_height = -(fbc_array[i] / 2);
//fillRect( x, y, width, height ) // Explanation of the parameters below
ctx.fillRect(bar_x, canvas.height, bar_width, bar_height);
}
}
</script>
</head>
<body>
<div id="mp3_player">
<div id="audio_box"></div>
<canvas id="analyser_render"></canvas>
</div>
【问题讨论】：
标签： javascript html audio youtube spectrum