MediaElementAudioSource outputs zeros due to CORS access restrictions local mp3 file
I have the following html page that I'm trying to show a class for demonstrating an audio visualizer with an mp3 stored locally:
<!doctype html>
<html>
<head>
<header name = "Access-Control-Allow-Origin" value = "*" />
<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 new instance of audio
var audio = new Audio();
audio.src = 'C:/Users/Adam/Desktop/1901.m4a';
audio.controls = true;
audio.loop = true;
audio.autoplay = true;
var canvas, ctx, source, context, analyser, fbc_array, bars, bar_x, bar_width, bar_height;
window.addEventListener("load", initMp3Player, false);
function frameLooper(){
window.webkitRequestAnimationFrame(frameLooper);
fbc_array = new Uint8Array(analyser.frequencyBinCount);
analyser.getByteFrequencyData(fbc_array);
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.fillStyle = "#00CCFF";
bars = 100;
for (var i = 0; i < bars; i++){
bar_x = i * 3;
bar_width = 2;
bar_height = -(fbc_array[i]/2);
ctx.fillRect(bar_x, canvas.height, bar_width, bar_height);
}
}
function initMp3Player(){
document.getElementById('audio_box').appendChild(audio);
context = new AudioContext();
analyser = context.createAnalyser();
canvas = document.getElementById('analyser_render');
ctx = canvas.getContext('2d');
source = context.createMediaElementSource(audio);
source.connect(analyser);
analyser.connect(context.destination);
frameLooper();
}
</script>
</head>
<body>
<div id = "mp3_player">
<div id = "audio_box"></div>
<canvas id = "analyser_render"></canvas>
</div>
</body>
I've gotten the mp3 file to play automatically before using all of the code in the script tag excluding what's below the line
audio.autoplay = true;
but when I include the frameLooper function I get the message "MediaElementAudioSource outputs zeros due to CORS access restrictions." Is there anyway to circumvent this since it's a local file?
Answer
Just after initializing the Audio object, add the following:
audio.crossOrigin = "anonymous";
This should prevent the CORS access restriction.