getid3_asf::GUIDtoBytestring

	 *
	 * @return string
	 */
	public static function GUIDtoBytestring($GUIDstring) {
		// Microsoft defines these 16-byte (128-bit) GUIDs in the strangest way:
		// first 4 bytes are in little-endian order
		// next 2 bytes are appended in little-endian order
		// next 2 bytes are appended in little-endian order
		// next 2 bytes are appended in big-endian order
		// next 6 bytes are appended in big-endian order

		// AaBbCcDd-EeFf-GgHh-IiJj-KkLlMmNnOoPp is stored as this 16-byte string:
		// $Dd $Cc $Bb $Aa $Ff $Ee $Hh $Gg $Ii $Jj $Kk $Ll $Mm $Nn $Oo $Pp

		$hexbytecharstring  = chr(hexdec(substr($GUIDstring,  6, 2)));
		$hexbytecharstring .= chr(hexdec(substr($GUIDstring,  4, 2)));
		$hexbytecharstring .= chr(hexdec(substr($GUIDstring,  2, 2)));
		$hexbytecharstring .= chr(hexdec(substr($GUIDstring,  0, 2)));

		$hexbytecharstring .= chr(hexdec(substr($GUIDstring, 11, 2)));
		$hexbytecharstring .= chr(hexdec(substr($GUIDstring,  9, 2)));

		$hexbytecharstring .= chr(hexdec(substr($GUIDstring, 16, 2)));
		$hexbytecharstring .= chr(hexdec(substr($GUIDstring, 14, 2)));

		$hexbytecharstring .= chr(hexdec(substr($GUIDstring, 19, 2)));
		$hexbytecharstring .= chr(hexdec(substr($GUIDstring, 21, 2)));

		$hexbytecharstring .= chr(hexdec(substr($GUIDstring, 24, 2)));
		$hexbytecharstring .= chr(hexdec(substr($GUIDstring, 26, 2)));
		$hexbytecharstring .= chr(hexdec(substr($GUIDstring, 28, 2)));
		$hexbytecharstring .= chr(hexdec(substr($GUIDstring, 30, 2)));
		$hexbytecharstring .= chr(hexdec(substr($GUIDstring, 32, 2)));
		$hexbytecharstring .= chr(hexdec(substr($GUIDstring, 34, 2)));