audio progress bar

var time = 60000/360, init = 0, per = 2*Math.PI/360;

var c=document.getElementById("myCanvas");
var ctx=c.getContext("2d");
ctx.beginPath();
ctx.arc(100,75,50,0,0*Math.PI);
ctx.stroke();


function redrawCircle(){
  init += per;
  ctx.clearRect(0,0,c.width,c.height);
  ctx.beginPath();
  ctx.arc(100,75,50,0,init);
  ctx.stroke();
}

setInterval(function(){
  redrawCircle();
}, time);