Audio Jitter Compensation via Feedback Test Signals
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Solution Overview
Problem
Real-time signal processing systems face challenges in accurately measuring and compensating for variable latency in audio signal processing, particularly in latency-sensitive applications like acoustic echo cancellation, in-car communication, and active noise control, where incorrect delay estimation can lead to echo leakage or system instability.
Innovation Solution
A system that measures and compensates for playback and capture delays by using a feedback channel to generate and analyze a test signal, synchronizing through system components that introduce jitter, and adjusting the delay measurement to maintain alignment and quality in audio processing applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If real-time signal processing systems process audio signals through batch processes, non-real-time processes, or near real-time processes, then system flexibility and resource utilization are improved, but variable latency and jitter are introduced that affect latency-sensitive applications
Solution Approach 1:
The system continuously measures the actual playback and capture delays using test signals and feedback channels, then uses this measured latency information to compensate for jitter in real-time. The feedback loop ensures that latency-sensitive applications receive accurate delay measurements despite variable system loading conditions.
Solution Approach 2:
A dedicated feedback channel and test signal mechanism are introduced as intermediaries to measure and characterize the system latency. This intermediary measurement system allows the main audio processing to continue while separately capturing latency data for compensation purposes.
2Device complexity
If systems assume fixed delay values for audio processing, then processing simplicity is improved, but accuracy deteriorates when actual delay varies due to system loading
Solution Approach 1:
The system performs preliminary measurement of playback and capture delays using test signals before processing actual audio content. This preliminary action establishes a baseline latency measurement that can be used for compensation, avoiding the need for complex real-time calculations during audio processing.
Solution Approach 2:
The system changes the approach from assuming a fixed delay parameter to dynamically measuring and updating the delay parameter based on actual system performance. The delay value becomes a variable that is continuously refined through test signal measurements rather than a static assumption.
3Productivity
If latency measurement is not performed accurately, then system operation speed is improved, but performance of latency-sensitive applications deteriorates due to echo leakage and instability
Solution Approach 1:
The latency measurement function is extracted as a separate, dedicated process that operates independently from the main audio processing pipeline. Test signals are injected through a separate feedback channel to measure delay without interfering with the primary audio processing operations, allowing both functions to run concurrently.
Solution Approach 2:
A feedback channel copies the audio signal path to create a measurement loop that can capture latency information without affecting the main processing path. This copying mechanism allows parallel operation of measurement and processing functions.
Data Source
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AI summary
A system and method receives one or more captured signals through a captured audio path and produces one or more playback signals through a playback audio path. The system and method executes one or more signal processing functions and measures the delays within the playback audio path and captured audio path during operation of the one or more signal processing functions. The system and method stores the measured delays in a memory and compensates the one or more signal processing functions for the playback delay and the capture delay.