/**
* Extracts the image size and WebP type from a file
*
- * @param string $chunks Chunks as extracted by RiffExtractor
+ * @param string $filename
* @return array|bool Header data array with entries 'compression', 'width' and 'height',
* where 'compression' can be 'lossy', 'lossless', 'animated' or 'unknown'. False if
* file is not a valid WebP file.