Patent ID: 7702404

Claim:
A method, implemented on an apparatus for processing a digital audio signal, of processing a digital audio signal, comprising: spectrally encoding, at the apparatus, the digital audio signal to generate audio band data components representing audio contributions of said digital audio signal in respective ones of a set of frequency bands; spectrally encoding, at the apparatus, a watermark audio signal using the same encoding as that applied to the digital audio signal, to generate watermark band data components representing audio contributions of said watermark audio signal in respective ones of said set of frequency bands; altering, at the apparatus, a subset comprising one or more of said audio band data components by combining or replacing one or more of said audio band data components with corresponding ones of said watermark band data components to produce a band-altered digital audio signal having altered band data components; generating, at the apparatus, recovery data to allow original values of said altered band data components to be reconstructed; encrypting, at the apparatus, said recovery data; and storing, at the apparatus, said band-altered digital audio signal and said encrypted recovery data in a physical memory unit.