'Write required metadata to the thumbnail
See http://standards.freedesktop.org/thumbnail-spec/latest/x142.html'

def add_tags(self, album, image_path):

    mtime = os.stat(album.artpath).st_mtime
    metadata = {'Thumb::URI': self.get_uri(album.artpath), 'Thumb::MTime': six.text_type(mtime)}
    try:
        self.write_metadata(image_path, metadata)
    except Exception:
        self._log.exception(u'could    not    write    metadata    to    {0}', util.displayable_path(image_path))
