Fuente: Wipo "digitalization" When inserting several types of digital watermark information into the digital information, the visual time stamp detection circuit extracts the time stamps corresponding to the visual data in the visual data stream and the digital watermark insertion circuit specifies the types of the digital watermark information to be inserted corresponding to the extracted time stamps and inserts the digital watermark information of the applicable types into the visual data so that such information is synthesized with the audio data by the mixer circuit.