Methods, apparatus and articles of manufacture to perform audio watermark decoding
First Claim
1. A method comprising:
- sampling an audio signal including a code embedded therein;
transforming the sampled audio signal into a frequency domain representation;
examining a first plurality of frequency components of the frequency domain representation to determine whether the code is detected in the first plurality of frequency components; and
in response to determining that the code is not detected in the first plurality of frequency components, examining a second plurality of frequency components of the frequency domain representation of the sampled audio signal to determine whether the code is detected in the second plurality of frequency components, the second plurality of frequency components being offset from the first plurality of frequency components by a first offset corresponding to a sampling frequency mismatch.
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Accused Products
Abstract
Example methods, apparatus and articles of manufacture to perform audio watermark decoding are disclosed. A disclosed example method includes receiving an audio signal including an audience measurement code embedded therein using a first plurality of frequency components, sampling the audio signal, transforming the sampled audio signal into a first frequency domain representation, determining whether the code is detectable in the first plurality of frequency components of the first frequency domain representation, and when the code is not detected in the first plurality of frequency components, examining a second plurality of frequency components of a second frequency domain representation to determine whether the code is detected, the second plurality of frequency components being offset from the first plurality of frequency components by a first offset, the first offset corresponding to a sampling frequency mismatch.
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Citations
20 Claims
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1. A method comprising:
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sampling an audio signal including a code embedded therein; transforming the sampled audio signal into a frequency domain representation; examining a first plurality of frequency components of the frequency domain representation to determine whether the code is detected in the first plurality of frequency components; and in response to determining that the code is not detected in the first plurality of frequency components, examining a second plurality of frequency components of the frequency domain representation of the sampled audio signal to determine whether the code is detected in the second plurality of frequency components, the second plurality of frequency components being offset from the first plurality of frequency components by a first offset corresponding to a sampling frequency mismatch. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus comprising:
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a sampler to sample an audio signal including a code embedded therein; a time-to-frequency domain converter to transform the sampled audio signal into a frequency domain representation; and a frequency domain decoder to examine a first plurality of frequency components of the frequency domain representation to determine whether the code is detected in the first plurality of frequency components, and, in response to a determination that the code is not detected in the first plurality of frequency components, the frequency domain decoder to examine a second plurality of frequency components of the frequency domain representation to determine whether the code is detected in the second plurality of frequency components, the second plurality of frequency components being offset from the first plurality of frequency components by a first offset that corresponds to a sampling frequency mismatch. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A storage device or storage disc storing machine-readable instructions that, when executed, cause a processor to at least:
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sample an audio signal that includes a code embedded therein; transform the sampled audio signal into a frequency domain representation; examine a first plurality of frequency components of the frequency domain representation to determine whether the code is detected in the first plurality of frequency components; and examine a second plurality of frequency components of the frequency domain representation of the sampled audio signal to determine whether the code is detected in the second plurality of frequency components based on a determination that the code is not detected in the first plurality of frequency components, the second plurality of frequency components to be offset from the first plurality of frequency components by a first offset that corresponds to a sampling frequency mismatch. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification