Stereo Audio ITD Estimation Using Noise-Adaptive Weighting
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Solution Overview
Problem
Existing generalized cross-correlation methods for stereo audio signal delay estimation suffer from low precision in noisy environments, leading to inaccurate sound image reconstruction and instability in decoded stereo audio signals.
Innovation Solution
A method and apparatus that differentiate between coherent and diffuse noise types in stereo audio signals, employing distinct algorithms for ITD estimation using different weighting functions based on noise coherence values, enhancing precision and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If generalized cross-correlation methods are used for ITD estimation, then algorithm complexity is low and real-time performance is good, but ITD estimation precision deteriorates in noisy environments
Solution Approach 1:
The patent changes the weighting function parameters based on noise coherence detection. When coherent noise is detected, a noise-robust weighting function is applied; otherwise, a standard weighting function is used. This dynamic parameter adjustment resolves the contradiction by adapting the algorithm to maintain precision without always increasing complexity.
Solution Approach 2:
The patent introduces dynamic switching between different ITD estimation algorithms based on noise coherence detection. The system transitions from a static single-algorithm approach to a dynamic multi-algorithm approach, selecting the appropriate algorithm based on environmental conditions, thereby maintaining precision without permanently increasing system complexity.
2Reliability
If standard weighting functions are used in noisy environments, then algorithm implementation is simple, but sound image accuracy and stability deteriorate
Solution Approach 1:
The patent introduces noise coherence detection as an intermediary mechanism that mediates between the simple standard algorithm and the more complex noise-robust algorithm. This intermediary evaluates the noise condition and selects the appropriate algorithm, improving reliability without always requiring the complex algorithm.
Solution Approach 2:
The patent segments the ITD estimation process into two distinct paths: one for coherent noise conditions and another for diffuse noise conditions. Each path uses an optimized algorithm suitable for its specific condition, improving overall reliability without requiring both complex algorithms to run simultaneously.
3Measurement precision
If a single ITD estimation algorithm is used for all noise conditions, then device complexity is low, but ITD estimation precision and sound quality deteriorate in coherent noise environments
Solution Approach 1:
The patent makes the algorithm selection dynamic rather than static. The noise coherence detection mechanism enables the system to adaptively switch between algorithms based on real-time noise conditions, resolving the contradiction by only increasing complexity when necessary for precision.
Solution Approach 2:
The patent changes the algorithmic parameters (weighting functions) based on detected noise characteristics. This parameter adaptation allows the system to maintain low complexity for standard conditions while achieving high precision when noise is detected, resolving the contradiction between precision and complexity.
Data Source
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AI summary
A stereo audio signal delay estimation method and apparatus are disclosed. The method may include: obtaining a current frame of a stereo audio signal (S401), where the current frame includes a first channel audio signal and a second channel audio signal; and if a signal type of a noise signal included in the current frame is a coherent noise signal type, estimating an inter-channel time difference of the current frame by using a first algorithm (S403); or if a signal type of a noise signal included in the current frame is a diffuse noise signal type, estimating an inter-channel time difference of the current frame by using a second algorithm (S403). The first algorithm includes weighting a frequency domain cross power spectrum of the current frame based on a first weighting function, the second algorithm includes weighting a frequency domain cross power spectrum of the current frame based on a second weighting function, and a construction factor of the first weighting function is different from that of the second weighting function. Different ITD estimation algorithms are used for stereo audio signals including different types of noise, improving ITD estimation precision of the stereo audio signal.