“Metadata” is a term used to describe data that ‘informs’ us about other data. In surveillance applications, it is the data relating to changes or events in a video stream. Metadata provides identity and context to the events, so they can be categorised, sorted, searched, and recovered more easily and provide information such as: • Real-time alarm triggering and notifications. • Post-event, forensic searching. • Statistical analysis and reporting. • Driving event or motion recording, reducing storage overhead