Method and apparatus for transmitting watermark data bits using a spread spectrum, and for regaining watermark data bits embedded in a spread spectrum

US7760790B2 · kind B2 · utility

Assignee

• Thomson Licensing · FR

Inventors

• Peter Georg Baum · Hannover, DE
• Walter Voessing · Hannover, DE

Key dates

• Filing date: Sep 13, 2004
• Grant date: Jul 20, 2010
• Expiry date: Nov 22, 2026

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04H2201/50
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

Spread spectrum technology is used for watermarking digital audio signals. To retrieve a watermark signal information bit from the spread spectrum at the receiver or decoder side, the received or replayed spectrum is convolved with a spreading function that is time-inverse with respect to the original spreading function. The pseudo noise sequences are modulated on carrier frequencies which are inserted at one or more frequency bands into the spectrum of an audio signal. The watermark signal decoder checks the frequency bands occupied by such carriers. The frequency band occupation information is signaled in advance, i.e. is transmitted already together with the frame data for the current frame, such that the watermark signal decoder knows before processing the following audio signal frame which carrier frequencies are occupied and must be used for the corresponding carrier demodulation, and which carrier frequencies need not be checked and demodulated.