The present invention relates to deriving and utilizing content
signatures. A content signature is a representation of a content item,
which is derived from the content item itself. According to the
invention, a method of generating a content signature for a signal is
provided. The method includes the steps of: i) dividing the signal into
at least one set; ii) transforming the set into a frequency-based domain;
iii) determining features of the transformed set; and iv) grouping the
features so as to form a content signature of the set.