protected function getMediaRelativePath($path)
    {
        $path = self::validatePath($path, true);

        if (substr($path, 0, $this->storageFolderNameLength) == $this->storageFolder) {
            return substr($path, $this->storageFolderNameLength);
        }

        throw new SystemException(sprintf('Cannot convert Media Library path "%s" to a path relative to the Library root.', $path));
    }