PHP function lấy thời gian độ dài file wav

function wavDur($file) {
    $fp = fopen($file, 'r');
    if (fread($fp,4) == 'RIFF') {
    fseek($fp, 20);
    $rawheader = fread($fp, 16);
    $header = unpack('vtype/vchannels/Vsamplerate/Vbytespersec/valignment/vbits',$rawheader);
    $pos = ftell($fp);
    while (fread($fp,4) != 'data' && !feof($fp)) {
    $pos++;
    fseek($fp,$pos);
    }
    $rawheader = fread($fp, 4);
    $data = unpack('Vdatasize',$rawheader);
    $sec = $data['datasize']/$header['bytespersec'];
    $minutes = intval(($sec / 60) % 60);
    $seconds = intval($sec % 60);
    return  round($sec);
    return str_pad($minutes,2,'0', STR_PAD_LEFT).':'.str_pad($seconds,2,'0', STR_PAD_LEFT);
    }
  }