Abstract: A system for processing audio-video data to produce metadata, has an input for receiving audio video data. A characteristic extraction unit is arranged to extract n multiple distinct characteristics from the received audio-video data. A data comparison unit is arranged to compare the n multiple distinct characteristics with data extracted from example audio-video data by comparing in n dimensional space to produce a value for each of f features of the audio-video data where f<n. A multi-dimensional metadata unit is arranged to receive the values for each feature and to produce a complex continuous metadata value of M dimensions for the audio-video data where M<f.