Patent ID: 8626504

Claim:
A method for generating a signature that identifies content of an audio signal, wherein the method performed by a device comprises: obtaining, by a device, a time-frequency representation of a set of blocks within a sequence of blocks of the audio signal, wherein the time-frequency representation comprises sets of spectral values, each set of spectral values representing all spectral components within at least a portion of the bandwidth of the audio signal in a respective block in the set of blocks; deriving, by a device, intermediate values from intensities of all the spectral values arranged in groups of one or more spectral values within a respective set of spectral values; and generating, by a device the signature that identifies content of the audio signal by projecting the intermediate values onto a set of random vectors, wherein the signature is represented by bits and each bit of the signature is derived from contributions from all of the intermediate values; wherein each respective vector in the set of random vectors has vector elements with values that are obtained from a difference between uniformly distributed random variables within a range from zero to one and an average of the uniformly distributed random variables for all vector elements of the respective vector; the projection of the intermediate values onto a respective random vector is obtained from an inner product of the intermediate values with the vector elements of the respective vector; and each component of the signature has either a first value when the projection of the intermediate values onto a corresponding random vector is greater than a threshold or has a second value when the projection of the intermediate values onto the corresponding random vector is less than a threshold, wherein the threshold is equal to a median of the projections of intermediate values onto the set of random vectors.