Methods, apparatus and articles of manufacture to perform audio watermark decoding
First Claim
1. A method comprising:
- 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 detected in the first plurality of frequency components of the first frequency domain representation;
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 of the sampled audio signal 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 first sampling frequency mismatch; and
when the code is not detected in the second plurality of frequency components, examining a third plurality of frequency components of a third frequency domain representation of the sampled audio signal to determine whether the code is detected, the third plurality of frequency components being offset from the first plurality of frequency components by a second offset different than the first offset, the second offset corresponding to a second 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.
25 Citations
21 Claims
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1. A method comprising:
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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 detected in the first plurality of frequency components of the first frequency domain representation; 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 of the sampled audio signal 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 first sampling frequency mismatch; and when the code is not detected in the second plurality of frequency components, examining a third plurality of frequency components of a third frequency domain representation of the sampled audio signal to determine whether the code is detected, the third plurality of frequency components being offset from the first plurality of frequency components by a second offset different than the first offset, the second offset corresponding to a second sampling frequency mismatch. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus comprising:
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an audio input interface to receive an audio signal including an audience measurement code embedded therein using a first plurality of frequency components; a sampler to sample the audio signal; a time-to-frequency domain converter to transform the sampled audio signal into a first frequency domain representation; and a frequency domain decoder to determine whether the code is detected 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, examine a second plurality of frequency components of a second frequency domain representation of the sampled audio signal 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 first sampling frequency mismatch, and when the code is not detected in the second plurality of frequency components, the frequency domain decoder to examine a third plurality of frequency components of a third frequency domain representation of the sampled audio signal to determine whether the code is detected, the third plurality of frequency components being offset from the first plurality of frequency components by a second offset different than the first offset, the second offset corresponding to a second sampling frequency mismatch. - View Dependent Claims (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 machine to at least:
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receive an audio signal including an audience measurement code embedded therein using a first plurality of frequency components; sample the audio signal; transform the sampled audio signal into a first frequency domain representation; determine whether the code is detected 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, examine a second plurality of frequency components of a second frequency domain representation of the sampled audio signal 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 first sampling frequency mismatch; and when the code is not detected in the second plurality of frequency components, examine a third plurality of frequency components of a third frequency domain representation of the sampled audio signal to determine whether the code is detected, the third plurality of frequency components being offset from the first plurality of frequency components by a second offset different than the first offset, the second offset corresponding to a second sampling frequency mismatch. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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Specification