Can getID3 get data of mp3 file that is input for FFT?

Question

I want to compare two pieces of music to find similarities. But actually, I don't understand what Fast Fourier Transform is. I don't even know the parameter of the FFT function(from https://gist.github.com/mbijon/1332348).

My questions are:

1. What are the parameters to FFT function?
2. Does getID3 function provide these parameters?
3. If not, how can I get these paramaters?

Here is my code.

<?php
    require_once('assets/getID3/getid3/getid3.php');
    require_once('FFT.php');
    $getID3 = new getID3;
    $ThisFileInfo = $getID3->analyze("music.mp3");
    $bit_rate = $ThisFileInfo['audio']['bitrate'];
    var_dump($bit_rate);
?>