Configurable QMF Filter Banks for Audio Output Resampling

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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 implementation of a configurable audio signal processor with analysis and synthesis filter banks, along with a controller, allows for varying sampling rates by modifying the frequency domain representation, reducing the complexity of filter banks and eliminating additional signal distortion through bandwidth adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If additional resampling functional modules (interpolator, up sampler, down sampler) 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 compatibilityVSAvoidcomputational resources

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the resampling function with the existing QMF filter bank structure by making the analysis and synthesis filter banks configurable. The same filter bank infrastructure is used for both audio processing and resampling, eliminating the need for separate resampling modules and reducing overall system complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The filter banks are designed to be dynamically configurable, allowing the number of analysis and synthesis channels to be adjusted based on the desired sampling rate. This dynamic configuration enables the system to adapt to different sampling rates without requiring fixed, dedicated resampling hardware for each rate.

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If uncommon sampling rates are used to increase audio bandwidth and scalability, then audio quality is improved, but compatibility with low-cost hardware D/A converters is lost

Engineering Contradiction:

Improveaudio bandwidthVSAvoidhardware compatibility

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The system changes the sampling rate parameter dynamically by configuring the filter bank channels appropriately. By adjusting the number of analysis and synthesis channels, the system can output at different sampling rates including standard rates that are compatible with common hardware D/A converters, while still supporting high-quality audio processing when needed.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If the number of analysis and synthesis filter bank channels is increased to support different sampling rates, then sampling rate flexibility is improved, but filter bank complexity increases

Engineering Contradiction:

Improvesampling rate flexibilityVSAvoidfilter bank complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The filter bank is designed as a universal, configurable structure that can operate with different numbers of channels depending on the required sampling rate. The same filter bank infrastructure serves multiple functions: audio processing and resampling to various rates, eliminating the need for multiple dedicated filter banks for different sampling rates.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Use of energy by moving object

If low bit rate operation is used to reduce computational resources, then energy efficiency is improved, but audio bandwidth is limited to below human audible range

Engineering Contradiction:

Improvecomputational resourcesVSAvoidaudio bandwidth

Core Design Contradiction:

Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The system uses partial action by selectively configuring the number of filter bank channels based on the required audio bandwidth. At low bit rates, fewer channels are used to reduce computational resources, while still maintaining adequate audio quality for the application. The system provides just enough processing capability needed for each specific operating condition rather than always using full capability.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11790928B2Resampling output signals of QMF based audio codecs

Publication Date: 2023.10.17 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.