Question

How can I play audio in reverse with the web audio API? I can’t seem to find anything in the API docs…

Answer 1

You could do something like this:

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;
    });
});

It’s a super simple example – but the point is basically that you can grab the Float32Array instance for each channel in the AudioBuffer and reverse them.