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index.js
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index.js
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var audio = document.getElementById('audio')
input.onchange = function(e) {
audio.src = URL.createObjectURL(this.files[0]);
audio.play()
startVisualizer()
// Hide file upload div. Show visualizer.
document.getElementById('step1').style.cssText = "display: none;"
document.getElementById('step2').style.cssText = ""
audio.onend = function(e) {
URL.revokeObjectURL(this.src);
}
}
document.getElementById('playDefaultLink').onclick = (e) => {
audio.play()
startVisualizer()
// Hide file upload div. Show visualizer.
document.getElementById('step1').style.cssText = "display: none;"
document.getElementById('step2').style.cssText = ""
}
function startVisualizer() {
var analyser = require('web-audio-analyser')(audio);
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
function update() {
var audioFreq = analyser.waveform()
// Clear canvas
ctx.fillStyle="black";
ctx.fillRect(0, 0, canvas.width, canvas.height);
// Set line style
var scaleFactor = 0.8;
ctx.strokeStyle = "white"
ctx.lineWidth = 1.5;
// Draw frequency lines
ctx.beginPath();
ctx.moveTo(0, canvas.height/2 - audioFreq[0]*scaleFactor);
for (let i = 0; i < audioFreq.length; i++) {
ctx.lineTo((canvas.width/audioFreq.length)*i, canvas.height/2 - audioFreq[i]*scaleFactor);
}
ctx.moveTo(0, canvas.height/2 + audioFreq[0]*scaleFactor);
for (let i = 0; i < audioFreq.length; i++) {
ctx.lineTo((canvas.width/audioFreq.length)*i, canvas.height/2 + audioFreq[i]*scaleFactor);
}
ctx.stroke();
requestAnimationFrame(update);
}
update()
}