Audio Signal Synchronization via Correlation Feedback
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Solution Overview
Problem
Synchronizing audio signals between internal and external audio reproduction devices, such as a television's internal speaker and a sound bar, is challenging due to differing delays in digital audio decoding processing, leading to potential sound delays.
Innovation Solution
A method involving measuring a superimposed sound signal, calculating intercorrelation or autocorrelation functions, estimating time shifts, modifying audio characteristics, and re-measuring to synchronize audio signals by applying appropriate delays or leads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If digital audio decoding processing is performed separately in television and external audio devices, then audio signals can be reproduced by multiple devices, but time delay differences occur between the audio signals
Solution Approach 1:
The system captures the superimposed audio signal from both devices, calculates correlation functions to measure time shifts, and uses this feedback to automatically adjust delay parameters. This closed-loop feedback mechanism eliminates time delays while preserving multi-device audio reproduction capability
Solution Approach 2:
The system dynamically changes the delay parameter of one audio device based on measured time shifts. By adjusting the delay parameter according to correlation analysis results, the system synchronizes audio output across multiple devices without affecting their individual reproduction capabilities
2Reliability
If manual synchronization adjustment is performed by the user, then synchronization can be achieved, but the process is complex and requires user expertise
Solution Approach 1:
The system performs self-synchronization by automatically capturing audio signals, calculating correlation functions to determine time shifts, and adjusting delay parameters without user intervention. This eliminates the need for manual adjustment while maintaining high synchronization accuracy
Solution Approach 2:
The system replaces manual mechanical adjustment with automated electronic signal processing. By using correlation function calculations and automatic delay adjustment, the system substitutes complex manual operations with efficient electronic computation
3Measurement precision
If correlation function calculation is performed on the superimposed audio signal, then precise time shift measurement is achieved, but processing time and computational complexity increase
Solution Approach 1:
The system calculates correlation functions only for the essential audio signal components to determine time shifts, avoiding unnecessary processing of all signal data. This partial action approach maintains measurement precision while reducing overall processing time
Data Source
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AI summary
A method for synchronising a first audio signal (Sa1) and a second audio signal (Sa2) coming from a same original audio signal, the method comprising the steps of: - measuring a superimposed sound signal; performing a processing of the superimposed sound signal comprising a calculation of an intercorrelation or autocorrelation function; estimating, from a first processed signal, an absolute value of a time delay (Δt) between the first audio signal and the second audio signal; modifying at least one characteristic of the first audio signal or the second audio signal; measuring again the superimposed sound signal; - performing again the processing of the superimposed sound signal in order to obtain a second processed signal (St2); estimating the sign of the time delay based on the second processed signal; synchronising the first audio signal and the second audio signal.