protected function tryToParseContentRange($contentRange)
    {
        // try to get the content range
        if (preg_match("/bytes ([\d]+)-([\d]+)\/([\d]+)/", $contentRange, $matches)) {
            $this->chunkedUpload = true;

            // write the bytes values
            $this->bytesStart = $this->convertToNumericValue($matches[1]);
            $this->bytesEnd = $this->convertToNumericValue($matches[2]);
            $this->bytesTotal = $this->convertToNumericValue($matches[3]);
        }
    }