Device for marking and restoring multimedia signals

摘要

The invention concerns a device for processing a signal comprising a signal transforming module ( 5 ) capable of producing a transformed signal (xi) from an original signal and a mixing module ( 10 ) for marking the transformed signal with a marking message (M). The mixing module ( 10 ) comprises: a formatting module ( 14 ) capable of calculating a response of the transformed signal (rx) to the demodulation of a first set of carriers (Gj) defined by keys protecting the message and of calculating a marking information ({bj}) based on said response and code words (U) associated with the marking message, a modulator ( 18 ) capable of modulating marking data supplied by the formatting module ( 14 ) with a given coefficient (Gij) of the carriers of the first set of carriers, and of modulating in amplitude the resulting coefficient by a corresponding quantity related to the energy weighting term of the marking message and to the set of carrier, thereby supplying a marking coefficient, an adder ( 20 ) capable of adding the marking coefficient to the corresponding coefficient of the original transformed signal.