Method for watermarking data
First Claim
1. A method of incorporating a watermark into a signal, comprising substituting a replaceable signal portion of the signal which has a substantially random attribute with a replacement signal, the replacement signal portion having a substantially random attribute which has been modulated by watermark data.
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Accused Products
Abstract
A method for inserting a watermark into an audio signal comprising substituting a noise-like signal portion with a replacement noise-like signal portion, and the replacement noise-like signal portion is modulated with watermark data. In a preferred embodiment Perceptual Noise Substitution is used to locate those portions of the audio signal which are noise-like and which may be replaced by synthetic noise modulated with watermark data. Advantageously the inventive method results in a signal having a synthetic noise signal portion which is modulated by watermark data but which is perceived merely as a noisy signal portion and not as watermark data carrying. Furthermore, watermarks incorporated by the inventive method may be adapted to be robust to various audio compression schemes.
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Citations
35 Claims
- 1. A method of incorporating a watermark into a signal, comprising substituting a replaceable signal portion of the signal which has a substantially random attribute with a replacement signal, the replacement signal portion having a substantially random attribute which has been modulated by watermark data.
- 26. A method of reading a signal which is provided with a watermark, comprising locating a replacement signal portion (10) and identifying the presence of the watermark in said replacement portion, the replacement signal portion having a substantially random attribute which has been modulated by watermark data, the replacement signal portion having replaced a replaceable signal portion which has a substantially random attribute.
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33. An encoder comprising a signal analyser, a random signal generator and a modulator, the signal analyser, random signal generator and modulator being arranged such that in use:
- (a) the signal analyser analyses a signal so as to determine a replaceable signal portion which has a substantially random attribute, (b) the modulator modulates a replacement signal portion generated by the random signal generator with watermark data, and (c) the replaceable signal portion is substituted by the replacement signal portion.
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34. A reader comprising a signal analyser, a random signal generator and a demodulator, the signal analyser, random signal generator and modulator being arranged such that in use:
- (a) the signal analyser analyses a signal in order to determine the presence of a watermark in the signal, (b) the watermark is incorporated into the signal by way of a replacement signal portion and (c) the replacement signal portion has a substantially random attribute which has been modulated by watermark data.
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35. A circuit for watermarking an input signal having a random component, the circuit comprising:
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a detector for the random component and a watermark source for deriving a watermark; and a combiner arrangement, including the detector, connected to be responsive to the input signal and the derived watermark for modifying the input signal so the detected random component thereof is replaced by the watermark.
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Specification