Spectral Audio Patching for Adaptive Bandwidth Extension

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Solution Overview

Problem

Existing bandwidth extension methods in audio coding, such as spectral band replication (SBR), lack flexibility and adaptability, leading to blocking artifacts and inefficient processing due to the use of a single patching algorithm that does not consider signal characteristics or implementation needs.

Innovation Solution

Implement a system that switches between multiple spectral domain patching algorithms, including harmonic transposition, non-harmonic copying-up SBR, and non-linear distortion, within the spectral domain to generate a synthesis audio signal, eliminating the need for time-to-spectral domain transformations and optimizing perceptual quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single patching algorithm is used in existing bandwidth extension methods, then the processing is simpler, but the adaptability to different signal characteristics is poor and blocking artifacts occur

Engineering Contradiction:

Improveadaptability to signal characteristicsVSAvoidprocessing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system dynamically switches between multiple patching algorithms (harmonic transposition, non-harmonic copying-up SBR, and non-linear distortion) based on signal characteristics. The patching control signal selects different algorithms adaptively, allowing the system to adjust its processing mode according to the input signal properties, thereby resolving the contradiction between adaptability and complexity.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the parameter of algorithm selection by introducing a patching control signal that indicates which patching algorithm to use. This allows the system to vary its processing approach (different patching algorithms) based on signal characteristics, improving adaptability while maintaining manageable complexity through parameter-based control.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If multiple patching algorithms are implemented to improve adaptability, then the flexibility increases, but the processing complexity increases

Engineering Contradiction:

Improveflexibility in bandwidth extensionVSAvoidprocessing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system implements multiple patching algorithms but manages complexity through dynamic selection rather than simultaneous processing. The patching control signal enables the system to activate only the necessary algorithm for each signal segment, providing flexibility when needed while keeping processing complexity low through selective activation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention uses parameter changes (patching control signal) to manage the complexity of multiple algorithms. By controlling which algorithm is active through a selection parameter, the system achieves high flexibility in bandwidth extension while avoiding the computational burden of running all algorithms simultaneously.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If time-to-spectral domain transformations are used in existing methods, then the processing is more flexible, but the processing complexity increases

Engineering Contradiction:

Improveease of spectral processingVSAvoidtransformation complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The invention extracts and performs patching operations directly in the spectral domain, taking out the need for time-to-spectral transformations. By working natively in the spectral domain, the system achieves the flexibility of spectral processing while eliminating the complexity of domain transformations.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUSRE50780E1Apparatus and method for generating a synthesis audio signal and for encoding an audio signal

Publication Date: 2026.02.03 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

AI summary

An apparatus for generating a synthesis audio signal using a patching control signal has a first converter, a spectral domain patch generator, a high frequency reconstruction manipulator and a combiner. The first converter is configured for converting a time portion of an audio signal into a spectral representation. The spectral domain patch generator is configured for performing a plurality of different spectral domain patching algorithms, wherein each patching algorithm generates a modified spectral representation having spectral components in an upper frequency band derived from corresponding spectral components in a core frequency band of the audio signal. The spectral domain patch generator is furthermore configured to select a first spectral domain patching algorithm from the plurality of patching algorithms for a first time portion and a second spectral domain patching algorithm from the plurality of patching algorithm for a second different time portion in accordance with the patching control signal to obtain the modified spectral representation.