如何在php中读取ppt文件

我想从php中的ppt文件中读取韩语、计数字符和单词。我使用了下面的php代码来读取ppt文件，但它不读取朝鲜语-

function parsePPT($filename) {
     // This approach uses detection of the string "chr(0f).Hex_value.chr(0x00).chr(0x00).chr(0x00)" to find text strings, which are then terminated by another NUL chr(0x00). [1] Get text between delimiters [2] 
    $fileHandle = fopen($filename, "r");
    $line = fread($fileHandle, filesize($filename));
    $lines = explode(chr(0x0f),$line);
    $outtext = '';
    foreach($lines as $thisline) {
        if (strpos($thisline, chr(0x00).chr(0x00).chr(0x00)) == 1) {
            $text_line = substr($thisline, 4);
            $end_pos   = strpos($text_line, chr(0x00));
            $text_line = substr($text_line, 0, $end_pos);
            $text_line = preg_replace("/[^a-zA-Z0-9's','.'-'n'r't@'/'_'(')]/"," ",$text_line);
            if (strlen($text_line) > 1) {
                $outtext.= substr($text_line, 0, $end_pos)."'n";
            }
        }
    }
    return $outtext;
}
$filename = "test_pptk.ppt";
$ppt_string = parsePPT($filename);

请告诉我php代码可以从ppt文件中读取韩语和其他语言。我还想计算这样的ppt文件中的字符数和字数。