How to get the size and duration of an mp3 file?

Question

I need to calculate the total length of an mp3 file.

Currently I am using a PHP class which I found @ http://www.zedwood.com/article/php-calculate-duration-of-mp3.

Answer 1

Perhaps the simplest solution is to use the audio html element to get the time duration and to obtain the size directly from the file returned by the FileReader object. A code example of this approach is shown below.

One down side of this and all the other solutions presented so far is the 10-20 second delay it takes for the audio tag's durationchanged event to fire when loading large, eg > 200MB files. Clearly there is a faster way to get this info because the duration is shown immediately when the file is entered into the browser as a file:///.... URL.

function checkMp3SizeAndDuration()
{    
    var files = document.getElementById('upload-file').files;
    var file = files[0];
    if (file.size > MAX_FILE_SIZE) {
        return;
    }

    var reader = new FileReader();
    var audio = document.createElement('audio');
    reader.onload = function (e) {
        audio.src = e.target.result
        audio.addEventListener('durationchange', function() {
            console.log("durationchange: " + audio.duration);
        },false);

        audio.addEventListener('onerror', function() {
            alert("Cannot get duration of this file.");
        }, false);
    };
    reader.readAsDataURL(file);
});