public static function compressFile($filepathSrc, $filepathDst = null, $level = 9)
	{
	    if (!isset($filepathDst)) {
	    	$filepathDst = $filepathSrc.'.gz';
	    }
	    $return = $filepathDst;
	    $mode = 'wb'.$level;
	    if ($fpOut = gzopen($filepathDst, $mode)) {
	        if ($fpIn = fopen($filepathSrc, 'rb')) {
	            while (!feof($fpIn)) {
	                gzwrite($fpOut, fread($fpIn, 1024*512));
	            }
	            fclose($fpIn);
	        } else {
	        	$return = false;
	        }
	        gzclose($fpOut);
	    } else {
	    	$return = false;
	    }
    	return $return;
	}