Can you possibly extend the audio filter with an “unknown” category? Showing all movies of which the audio language could not be determined (for example because it was not set, empty, an unknown string or whatever reason).
For the subtitle filter it would be great to have an option “unknown” for subtitles that did not match the ISO639(-1 and -2) language lists and an option for movies that do not contain any subtitles? Those filters would make it incredibly easier to manage the libraries :).
