QMF Filter Bank Resampling for Low-Complexity Audio Codecs

Solution Overview

Problem

Current audio processing technologies face challenges in efficiently handling different sampling rates, particularly at low bit rates, which require additional computational resources and are not compatible with low-cost hardware, limiting audio bandwidth and increasing complexity.

Innovation Solution

The proposed solution involves a configurable audio signal processor with analysis and synthesis filter banks that adjust the number of channels based on configuration settings, allowing for different sampling rates and reducing computational complexity by modifying the frequency domain representation, thereby eliminating the need for high-complexity resamplers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If additional resampling functional modules are used to adapt output sampling rate, then sampling rate compatibility is improved, but computational resources and device complexity increase significantly

Engineering Contradiction:

Improvesampling rate compatibilityVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the resampling function with the existing analysis and synthesis filter banks already present in the audio codec. By controlling the number of channels in these filter banks, the system achieves sampling rate adaptation without adding separate resampling modules, thus reducing computational overhead and device complexity while maintaining sampling rate compatibility

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The analysis and synthesis filter banks are designed to serve multiple functions: both audio signal processing and sampling rate adaptation. By adjusting the number of channels in these universal components, the system can handle different sampling rates without requiring dedicated resampling hardware, thereby reducing overall device complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If additional resampling functional modules are used to adapt output sampling rate, then sampling rate compatibility is improved, but computational resources increase significantly

Engineering Contradiction:

Improvesampling rate compatibilityVSAvoidcomputational resources

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent merges the resampling function with the existing analysis and synthesis filter banks already present in the audio codec. By controlling the number of channels in these filter banks, the system achieves sampling rate adaptation without adding separate resampling modules, thus reducing computational overhead and device complexity while maintaining sampling rate compatibility

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The filter banks perform resampling as a byproduct of their normal audio processing function. The system uses its existing structural components to serve the additional purpose of sampling rate adaptation, eliminating the need for separate dedicated resampling computations and thereby reducing overall computational resource usage

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If conventional resampling technology is used, then sampling rate adaptation is achieved, but signal distortion increases

Engineering Contradiction:

Improvesampling rate adaptationVSAvoidsignal distortion

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent merges the resampling function with the existing analysis and synthesis filter banks already present in the audio codec. By controlling the number of channels in these filter banks, the system achieves sampling rate adaptation without adding separate resampling modules, thus reducing computational overhead and device complexity while maintaining sampling rate compatibility

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The system dynamically adjusts the number of channels in the analysis and synthesis filter banks based on the desired sampling rate. This dynamic reconfiguration allows the filter banks to adapt their structure to minimize signal distortion while achieving the target sampling rate, rather than using fixed conventional resampling approaches

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11961531B2Resampling output signals of QMF based audio codec

Publication Date: 2024.04.16 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

AI summary

An apparatus for processing an audio signal includes a configurable first audio signal processor for processing the audio signal in accordance with different configuration settings to obtain a processed audio signal, wherein the apparatus is adapted so that different configuration settings result in different sampling rates of the processed audio signal. The apparatus furthermore includes n analysis filter bank having a first number of analysis filter bank channels, a synthesis filter bank having a second number of synthesis filter bank channels, a second audio processor being adapted to receive and process an audio signal having a predetermined sampling rate, and a controller for controlling the first number of analysis filter bank channels or the second number of synthesis filter bank channels in accordance with a configuration setting.