Detection of signal modifications in audio streams with embedded code
First Claim
Patent Images
1. A method of processing a signal comprising:
- receiving the signal at a receiver to produce a received signal;
decoding the received signal so as to read a coefficient value count code from the received signal;
performing a transform of the received signal to produce transform coefficients;
counting those transform coefficients having a predetermined value;
comparing the coefficient value count contained in the coefficient value count code to the transform coefficient count; and
selectively further processing or discarding the received signal based upon the comparison of the coefficient value count contained in the coefficient value count code to the transform coefficient count.
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Abstract
An encoder transforms at least a portion of a signal, counts the resulting transform coefficients having a zero value, and encodes the signal with the zero count. A decoder decodes the signal in order to recover the zero count. The decoder may also determine its own zero count of the signal as received and may compare the zero count that it determines to the recovered zero count. The decoder may be arranged to detect compression/decompression based upon results from the comparison, and/or the decoder may be arranged to prevent use of a device based upon results from the comparison.
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Citations
24 Claims
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1. A method of processing a signal comprising:
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receiving the signal at a receiver to produce a received signal; decoding the received signal so as to read a coefficient value count code from the received signal; performing a transform of the received signal to produce transform coefficients; counting those transform coefficients having a predetermined value; comparing the coefficient value count contained in the coefficient value count code to the transform coefficient count; and selectively further processing or discarding the received signal based upon the comparison of the coefficient value count contained in the coefficient value count code to the transform coefficient count. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A decoder having an input and an output, wherein the input receives a signal, wherein the decoder:
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decodes the input signal so as to read a coefficient value count code from the input signal; transforms the input signal to produce transform coefficients; counts those transform coefficients having a predetermined value; compares the coefficient value count contained in the coefficient value count code to the transform coefficient count; and selectively further processes or discards the input signal based upon the comparison of the coefficient value count contained in the coefficient value count code to the transform coefficient count. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification