Method of identifying the recurrence in a video stream of a stored sequence

A video stream is received and hash values are generated for the frames. Frames with matching values are identified by comparing hash values from the video stream to hash values for frames of a stored sequence. These are used to identify candidate sub-sequences of frames. The sub-sequences are compared and when a threshold level of frames with hash values matched to frames of another sub-sequences are detected, a match is identified. Groups of subsequences are compared with the candidate subsequences to determine whether a threshold level of similarity is met when recurrence is detected a signal is generated indicating a recurrence in the video stream of the stored sequence.