libdvdetect provides fast database lookup for DVDs
...It reads the structure (e.g. titles and chapters) and generates a special checksum to look up the database.
More details at http://www.dvdetect.de. The database can also be searched using a web browser at http://search.dvdetect.de/.
For those who are curious I suggest downloading the binaries from https://sourceforge.net/projects/libdvdetect/files/binaries/ to try it out (windows only).