public function mimetypes($doc = null, $docinfo = null)
 {
     global $Opt;
     if ($this->dtype > 0 && !$this->option) {
         return null;
     }
     $otype = $this->option ? $this->option->type : "pdf";
     $mimetypes = array();
     if (PaperOption::type_takes_pdf($otype)) {
         $mimetypes[] = Mimetype::lookup(".pdf");
     }
     if (!$this->option && !defval($Opt, "disablePS")) {
         $mimetypes[] = Mimetype::lookup(".ps");
     }
     if ($otype == "slides") {
         $mimetypes[] = Mimetype::lookup(".ppt");
         $mimetypes[] = Mimetype::lookup(".pptx");
     }
     if ($otype == "video") {
         $mimetypes[] = Mimetype::lookup(".mp4");
         $mimetypes[] = Mimetype::lookup(".avi");
     }
     return $mimetypes;
 }