QMF Audio Codec Resampling via Configurable Filter Bank Channels

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current audio processing technologies face challenges in efficiently adapting to different sampling rates, particularly at low bit rates, which limits compatibility with low-cost hardware and increases computational resources due to the need for additional resampling steps and high-complexity resamplers.

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 flexible sampling rate changes by modifying the frequency domain representation, reducing the complexity of resampling, and eliminating additional signal distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

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

Engineering Contradiction:

Improvesampling rate compatibilityVSAvoidresampling module complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the resampling functionality with the existing audio processing pipeline by using the analysis and synthesis filter banks that are already part of the codec structure. Instead of adding separate resampling modules, the invention repurposes the filter banks to perform both audio coding and resampling functions, thereby avoiding additional complexity while maintaining sampling rate adaptability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The analysis and synthesis filter banks are designed to serve multiple functions: they perform both the audio coding operations and the resampling operations. By making these filter banks configurable with variable numbers of channels, they can adapt to different sampling rates while remaining part of the core audio processing unit, thus achieving universality without increasing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If the number of filter bank channels is increased to support different sampling rates, then the sampling rate flexibility is improved, but the computational resources increase

Engineering Contradiction:

Improvesampling rate flexibilityVSAvoidcomputational resources

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic configurability of the filter bank channels, allowing the number of channels to be adjusted based on the desired sampling rate. This dynamic adaptation enables the system to optimize computational resources by using only the necessary number of channels for the current operating condition, rather than maintaining a fixed high-channel configuration for all possible sampling rates.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the parameter of filter bank channel count to achieve different sampling rates. By varying this parameter dynamically, the system can adapt to different sampling rate requirements while controlling computational resource usage, as the channel count directly determines both the sampling rate capability and the processing load.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If conventional resampling methods are used, then the sampling rate adaptation is achieved, but signal distortion is introduced

Engineering Contradiction:

Improvesampling rate adaptationVSAvoidsignal distortion

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces conventional mechanical resampling methods (interpolators and decimators) with a filter bank-based approach. The analysis filter bank transforms the input signal into frequency subbands, and the synthesis filter bank reconstructs the signal at the desired sampling rate. This substitution eliminates the signal distortion inherent in traditional resampling by using orthogonal filter bank properties that preserve signal integrity during the transformation and reconstruction process.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11804232B2Resampling output signals of QMF based audio codecs

Publication Date: 2023.10.31 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.