Patent ID: 8300820
Filing Date: 2012-10-30
Classification: G10L

Abstract:
1. Method of embedding a digital watermark in a useful signal, in particular an audio signal, using one of a programmable computer, a programmable computer network, and a further programmable equipment, wherein the useful signal (x n ) represents the evolution of a spectrum comprising useful signal frequencies, over time, and the digital watermark includes a watermark bit sequence, each bit of the watermark bit sequence representing one of a first state and a second state, characterized in that for imprinting the first state on the useful signal, the ratio of a first spectral amplitude (A f ) of the useful signal at a first imprinting frequency (f 1 ) to a second spectral amplitude (A g ) of the useful signal at a second imprinting frequency (g 1 ) is established to be higher or equal to a first value of a threshold parameter (y s ), and for imprinting the second state, the ratio of the second spectral amplitude (A g ) of the useful signal at the second imprinting frequency (g 1 ) to a first spectral amplitude (A f ) of the useful signal at a first imprinting frequency (f 1 ) is established to be higher or equal to a second value of the threshold parameter (y s ), forming the digital watermark containing auxiliary data, and embedding the digital watermark in the useful signal to generate a modulated useful signal incorporating the auxiliary data, characterized in that for imprinting the first state, the corresponding ratio is adjusted by decreasing the second spectral amplitude (A