Time-Domain Filter Coefficient Updating for Low-Latency Audio
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Solution Overview
Problem
Time domain filtering in audio signal processing faces challenges in adapting filter coefficients in real-time to match the time-varying nature of audio signals, leading to suboptimal frequency response and increased latency.
Innovation Solution
A method and system for adaptively updating filter coefficients by analyzing audio signals to determine target gains for each subband, iteratively selecting and updating coefficients based on a least square method and a mapping matrix, allowing for real-time adjustment of filter coefficients to approximate the target frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If time domain filtering is used to achieve ultra-low latency and improved linear convolution, then processing speed and convolution accuracy are improved, but the filter coefficients cannot be adjusted in real-time to match the time-varying nature of audio signals
Solution Approach 1:
The patent applies dynamics by transitioning from static pre-trained filter coefficients to dynamic real-time coefficient adaptation. The system continuously updates filter coefficients based on current audio signal characteristics through iterative optimization, allowing the filter to adapt its frequency response dynamically to match time-varying audio content while maintaining time domain processing advantages.
Solution Approach 2:
The patent implements parameter changes by modifying filter coefficients in real-time based on audio signal analysis. The system analyzes audio characteristics and adjusts filter parameters (coefficients) iteratively to approximate target frequency responses, enabling the filter to respond to changing audio conditions without switching to frequency domain processing.
2Adaptability or versatility
If frequency domain filtering is used to easily adjust frequency response by changing subband gains, then frequency response adaptability is improved, but processing latency increases and linear convolution accuracy deteriorates
Solution Approach 1:
The patent replaces the mechanical frequency domain transformation approach with a time domain iterative optimization system. Instead of transforming audio to frequency domain, applying gains, and transforming back (which causes latency and convolution issues), the system directly adjusts time domain filter coefficients through iterative mathematical optimization to achieve the same frequency response adaptation goals.
3Device complexity
If pre-trained offline filter coefficients are used to simplify the filtering process, then device complexity is reduced, but the filter cannot adapt to the time-varying nature of audio signals
Solution Approach 1:
The patent implements self-service by enabling the filter to automatically adapt its own coefficients based on the audio signal it processes. The system performs self-adjustment through iterative optimization, analyzing the audio characteristics and modifying its filter coefficients autonomously without requiring external retraining or manual intervention, thus achieving adaptability while maintaining operational simplicity.
Data Source
AI summary
Example embodiments disclosed herein relate to filter coefficient updating in time domain filtering. A method of processing an audio signal is disclosed. The method includes obtaining a predetermined number of target gains for a first portion of the audio signal by analyzing the first portion of the audio signal. Each of the target gains is corresponding to a subband of the audio signal. The method also includes determining filter coefficients for time domain filtering the first portion of the audio signal so as to approximate a frequency response given by the target gains. The filter coefficients are determined by iteratively selecting at least one target gain from the target gains and updating the filter coefficient based on the selected at least one target gain. Corresponding system and computer program product for processing an audio signal are also disclosed.