Web Audio tricks

play-reverse.js

// copy from https://stackoverflow.com/questions/9874167/how-can-i-play-audio-in-reverse-with-web-audio-api
var context = new AudioContext(),
    request = new XMLHttpRequest();
request.open('GET', 'path/to/audio.mp3', true);
request.responseType = 'arraybuffer';
request.addEventListener('load', function(){
    context.decodeAudioData(request.response, function(buffer){
        var source = context.createBufferSource();
        Array.prototype.reverse.call( buffer.getChannelData(0) );
        Array.prototype.reverse.call( buffer.getChannelData(1) );
        source.buffer = buffer;
    });
});