Watermark Extraction via Gain and Delay Adjustment
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Solution Overview
Problem
Existing audio watermarking systems face challenges in achieving 100% reliability and inaudibility, as they require trade-offs between watermark decoding reliability and audible degradation, and lack effective methods to extract and enhance watermarks independently of encoder internals or real-world environmental degradations.
Innovation Solution
A system and method for extracting and enhancing watermarks from the output of a watermarking encoder, involving gain and delay adjustments to compensate for encoder-induced changes, and using spectral analysis to improve watermark detectability and decoding reliability while minimizing audible impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If watermarking modifies the original audio by adding new content or changing existing audio components to achieve 100% encoding reliability, then the watermark decoding reliability is improved, but the audio becomes audible and degraded
Solution Approach 1:
The patent extracts the watermark signal from the watermarked audio output by subtracting the original audio from the watermarked audio. This separation allows the watermark to be processed independently, enabling enhancement of the watermark signal without further modifying the original audio, thus resolving the contradiction between reliability and audibility.
Solution Approach 2:
The patent monitors the extracted watermark signal and uses this information to intelligently control the watermarking process. By feeding back watermark detection results, the system can adjust watermarking parameters to maintain reliability while minimizing audible degradation, as the feedback loop allows dynamic optimization based on actual watermark performance.
2Measurement precision
If adaptive filters are used to compensate for encoder changes to enable accurate watermark extraction, then the extraction accuracy is improved, but the method fails because the filter cannot fully compensate for unknown time-varying watermarking signal additions
Solution Approach 1:
The patent introduces an intermediary approach by using spectral analysis and signal subtraction methods that do not rely on adaptive filtering. Instead of trying to compensate for encoder changes through filtering, the system directly extracts the watermark by removing the original audio component, bypassing the limitations of adaptive filters with unknown time-varying signals.
3Reliability
If watermarking is applied to ensure 100% reliability across all broadcast content, then the watermark decoding reliability is improved, but failures concentrate in specific announcers, shows, or music types causing revenue loss
Solution Approach 1:
The patent implements dynamic watermarking by monitoring watermark extraction success in real-time and adjusting watermarking parameters based on the specific audio content being processed. This dynamic adaptation allows the system to maintain high reliability across diverse content types by optimizing watermark strength and characteristics for each announcer, show, or music genre rather than using a fixed watermarking approach.
Data Source
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AI summary
A device for extracting a watermark signal from an output signal of a watermarking encoder in which the output signal includes an input signal portion corresponding to an input signal to the watermarking encoder and a watermark signal portion corresponding to the watermark signal includes an input configured to receive the input signal and the output signal. The device further includes an adjustment signal generator configured to generate a gain adjustment signal and a delay adjustment signal based on the input signal and the output signal, a gain and delay adjustor configured to adjust gain and delay of the output signal or the input signal based on the gain adjustment signal and the delay adjustment signal, respectively, to generate an adjusted output signal or an adjusted input signal, respectively, and an output configured to transmit a difference between the input signal and the adjusted output signal or a difference between the adjusted input signal and the output signal as the watermark signal.