1. A digital content encoder operable to encode a temporal sequence of digital data, comprising: a coarse digital fingerprint generator operable to generate a coarse digital fingerprint characterising the digital data in an interval of the temporal sequence; a fine digital fingerprint generator operable to generate a plurality of fine digital fingerprints for the interval, each fine digital fingerprint characterising the digital data in a respective sub-interval of the interval; and an encoder operable to selectively apply loss-less compression encoding to the fine digital fingerprints for the interval such that at least one, but not all, of the fine digital fingerprints is compression encoded, and operable to apply non-compression encoding to at least one fine digital fingerprint that is not compression encoded.