Patent ID: 8108681

Claim:
A method for protecting a digital audio data stream representing an audio signal, the digital audio data stream comprising a plurality of samples, each sample corresponding to a respective time and representing, as a digital data value comprising a plurality of bits in pre-defined bit positions, an amplitude of the audio signal at the corresponding respective time, the method comprising: selecting, for each sample of a subset of said plurality of samples, a single respective bit position within the sample for storing a corresponding bit of a digital watermark in the digital audio data stream in time domain, by choosing a spread function characterising the plurality of the selected bit positions, wherein the spread function comprises at least one Gaussian curve, the at least one Gaussian curve being defined by spread function parameters including: a) a point of time corresponding to a peak of the Gaussian curve, b) a standard deviation of the Gaussian curve; c) a time interval between samples selected for storing the watermark; and d) the bit position of the sample storing the watermark at the peak of the Gaussian curve; and performing one of: (I) embedding said digital watermark in the digital audio data stream by storing each respective bit of digital watermark data at the respective bit position within the corresponding sample of the digital audio data stream selected by said selecting, for each sample of a subset of said plurality of samples, a single respective bit position within the sample for storing a corresponding bit of a digital watermark in the digital audio data stream in time domain; and (II) extracting said digital watermark from the digital audio data stream by extracting each respective bit of digital watermark data at the respective bit position within the corresponding sample of the digital audio data stream selected by said selecting, for each sample of a subset of said plurality of samples, a single respective bit position within the sample for storing a corresponding bit of a digital watermark in the digital audio data stream in time domain.