/* Pause an audio clip with a fade out effect on volume */
function fadeOut(id, fadeTime) {
    // Checks to see if id is empty
    id = typeof id !== 'undefined' ? id : null;

    // Detect if only fadeTime was specified, and mis-interpreted as the id variable
    if (isNumber(id)) {
        fadeTime = id;
        id = null;
    }

    // Sets default fadeTime to fade to 1s (1000ms)
    fadeTime = typeof fadeTime !== 'undefined' ? fadeTime : 1000;

    if (id !== null) {
        id = normaliseID(id);
        if(document[hidden]){
            animateFadeOut(id, Math.round((($(id)[0].volume / fadeTime) * 100)*100)/100);
        }else{
            $(id).animate({volume: 0},fadeTime, function() { this.pause(); });
        }
    } else {
        $("audio").each(function () { $(this).animate({volume:0}, fadeTime, function() { this.pause(); }); });
    }
}

var i=0;
function animateFadeOut(id, step){i=0;
    var inter = window.setInterval(function() {
        console.log("vol: ",$(id)[0].volume, " call: ",i, " step val: ",step );i++;
        $(id)[0].volume -=step;
        if($(id)[0].volume - step <= 0){window.clearInterval(inter);}
    }, 100);
}