I use setInterval
to wait for the content loaded. I hope this can help you to solve that problem.
var $audio = $('#audio');
var src = $audio.attr('src');
var a;
a = window.setInterval(function(){
src = $audio.attr('src');
if(src != undefined){
window.clearInterval(a);
$('audio').mediaelementplayer({
audioWidth: '100%'
});
}
}, 0);