Audio Watermark Decoder Frequency Offset Compensation
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Solution Overview
Problem
Current media monitoring systems face challenges in accurately detecting and decoding audience measurement codes embedded in audio signals, particularly due to sampling frequency mismatches that can offset the frequency components, leading to impaired code detection and extraction.
Innovation Solution
The proposed solution involves an audio watermark decoding method and apparatus that samples the audio signal, transforms it into a frequency domain representation, and uses a frequency domain decoder to detect the code in the initial frequency components. If the code is not detected, it examines offset frequency components corresponding to a sampling frequency mismatch, allowing for compensation and accurate decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the code is embedded in the audio signal using specific frequency components, then the code can be detected and extracted, but sampling frequency mismatches cause the frequency components to be offset, leading to impaired code detection
Solution Approach 1:
The system dynamically adjusts the frequency components examined by the decoder based on detected sampling frequency mismatches. Instead of using fixed frequency components, the decoder adapts to frequency offsets by examining shifted frequency ranges, allowing reliable code extraction despite variations in sampling rates between encoder and decoder
Solution Approach 2:
The system changes the frequency parameter examined by the decoder in response to detected mismatches. When a sampling frequency mismatch is detected, the system modifies which frequency components are analyzed, shifting the frequency range to compensate for the offset caused by the mismatch
2Productivity
If the decoder examines only the initial frequency components, then the decoding process is efficient, but code detection fails when sampling frequency mismatches offset the frequency components
Solution Approach 1:
The decoder dynamically determines which frequency components to examine based on mismatch detection. Initially, it examines the expected frequency components for efficiency, but when mismatches are detected, it transitions to examining offset frequency components to maintain detection accuracy
Solution Approach 2:
The system performs preliminary examination of the initial frequency components as expected, and only when code detection fails does it proceed to examine offset frequency components. This preliminary approach maintains efficiency while providing a fallback mechanism for accuracy
Data Source
AI summary
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.