Parallel Audio Analysis With Time-Domain Filtering for Low Latency

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Solution Overview

Problem

Conventional audio signal processing systems face a tradeoff between latency, computational complexity, and signal distortion, particularly in real-time processing applications, where high latency and harmonic distortions are common due to time-to-frequency transforming and critically sampled filterbanks.

Innovation Solution

A system and method for parallel audio signal analysis and processing that filters audio signals in the time domain without time-to-frequency transforming, using a time domain filter controlled by processing parameters determined during analysis, which reduces latency and avoids harmonic distortion, allowing for real-time processing and flexible filter design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If time-to-frequency transforming and filterbanks are used for audio signal analysis, then signal analysis capability is improved, but processing latency increases

Engineering Contradiction:

Improvesignal analysis capabilityVSAvoidprocessing latency

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system divides audio processing into two independent parallel paths: analysis path (time-to-frequency transforming) and processing path (time domain filtering). This segmentation allows each path to be optimized independently, with the analysis path providing detailed spectral information and the processing path maintaining low latency through time domain operations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The audio signal is pre-processed in the time domain using filtering operations before or during the analysis process. By performing time domain filtering in parallel with the analysis, the system prepares the signal for processing without waiting for the frequency domain analysis to complete, thereby reducing overall processing latency.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If critically sampled filterbanks are used for audio signal processing, then computational complexity is reduced, but harmonic distortions are introduced

Engineering Contradiction:

Improvecomputational complexityVSAvoidharmonic distortions

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

Instead of transforming to frequency domain and then back (conventional approach), the system inverts the approach by performing the essential processing operations directly in the time domain using filterbanks, avoiding the forward and inverse transforms that cause harmonic distortions. This time domain processing achieves the same filtering objectives without the distortion-introducing transforms.

Inventive Principle:

Principle #13The other way round (Inversion)

3Manufacturing precision

If filterbanks are designed for perfect reconstruction, then signal reconstruction quality is improved, but band isolation and linear convolution issues are introduced

Engineering Contradiction:

Improvesignal reconstruction qualityVSAvoidband isolation and linear convolution issues

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The system extracts and removes the inverse transforming step from the conventional audio processing chain. By taking out the frequency-to-time transforming operation, the system avoids the perfect reconstruction constraints and their associated problems (band isolation and linear convolution issues) while maintaining the beneficial frequency domain analysis capabilities through the separate analysis path.

Inventive Principle:

Principle #2Taking out (Extraction)

4Measurement precision

If framing and filterbanks are used for audio signal processing, then signal analysis is enhanced, but processing latency is increased

Engineering Contradiction:

Improvesignal analysisVSAvoidprocessing latency

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system maintains continuous time domain processing through parallel filtering operations that operate continuously on the audio signal without interruption for frame-based processing. This continuous action in the time domain path ensures low latency processing while the separate analysis path performs the detailed signal analysis, allowing both functions to proceed without mutual interference or delay.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS10405093B2Separated audio analysis and processing

Publication Date: 2019.09.03 DOLBY LABORATORIES LICENSING CORP

AI summary

Example embodiments disclosed herein relate to separated audio analysis and processing. A system for processing an audio signal is disclosed. The system includes an audio analysis module configured to analyze an input audio signal to determine a processing parameter for the input audio signal, the input audio signal being represented in time domain. The system also includes an audio processing module configured to process the input audio signal in parallel with the audio analysis module. The audio processing module includes a time domain filter configured to filter the input audio signal to obtain an output audio signal in the time domain, and a filter controller configured to control a filter coefficient of the time domain filter based on the processing parameter determined by the audio analysis module. Corresponding method and computer program product of processing an audio signal are also disclosed.