PHP MP3 playlist

<?php
 
       $dir = 'directory_of_mp3_files';
       $file_type = 'mp3';
 
       $play_list = '<?xml version=\'1.0\' encoding=\'UTF-8\' standalone=\'yes\'?>';
       $play_list .= "<playlist>";
 
       // Open directory, read contents and add to file_list if correct file_type
       if (is_dir($dir)) {
          if ($dh = opendir($dir)) {
             while (($file = readdir($dh)) !== false) {
                if ($file != '.' && $file != '..') {
                   $name_array = explode('.', $file);
 
                   // if file has .mp3 extension
                   if ($name_array[1] == $file_type) {
                      $play_list .= '<song>';
                      $file = "$dir/$file";
                      $play_list .= '<file>' . $file . '</file>';
                      $mp3 = fopen($file, "r");
                       fseek($mp3, -128, SEEK_END);
                       $tag = fread($mp3, 3);
 
                       // if id3 tag is found...
                       if ($tag == "TAG") {
                          $play_list .= '<title>' . trim(fread($mp3, 30)) . '</title>';
                          $play_list .= '<artist>' . trim(fread($mp3, 30)) .'</artist>';
 
                       // if no id3 tag...
                       } else {
                          $play_list .= '<title>unknown title</title>';
                          $play_list .= '<artist>unknown artist</artist>';
                       }
 
                       // close file
                       fclose($mp3);
                       $play_list .= '</song>';
                   }
                }
             }
 
             // close directory
             closedir($dh);
             $play_list .= '</playlist>';
 
             // echo the xml file
             echo "$play_list";
          }
       }
 
    ?>