Audio Signal Synthesis with Adaptive Patching for Spectral Band Replication

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Solution Overview

Problem

The existing MPEG-4 Audio standard lacks flexibility in adapting patching algorithms for different audio signals and coding schemes, leading to inefficient high-frequency signal generation in spectral band replication, which results in perceptual degradation and limited bit rate reduction.

Innovation Solution

An audio signal synthesizer that employs a patch generator to select between multiple patching algorithms based on control information, allowing for independent operation of patching and further processing in separate domains, enabling flexible application of different patching algorithms to different signal portions and optimizing spectral band replication parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single patching algorithm is used for all audio signals in the MPEG-4 standard, then the processing is simple and unified, but the system lacks flexibility to adapt to different audio signals and coding schemes

Engineering Contradiction:

Improveflexibility to adapt patching algorithmsVSAvoidcomplexity of multiple patching algorithms

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system dynamically selects between different patching algorithms (time-domain and frequency-domain) based on the characteristics of the audio signal and coding scheme. The patch generator adapts its operation mode according to control information, allowing the system to be flexible without permanently maintaining complex structures for all possible algorithms simultaneously.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes operational parameters by selecting different patching algorithms based on signal characteristics. Control information indicates whether to use time-domain patching (for certain signal types) or frequency-domain patching (for other types), effectively changing the processing parameters to match the input signal properties.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If patching and further processing are combined in the same filterbank domain, then the processing is integrated and efficient, but different patching algorithms cannot be implemented flexibly

Engineering Contradiction:

Improveimplementation of different patching algorithmsVSAvoidseparation of patching and processing domains

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system segments the processing into two independent domains: patching operations and further processing operations. The patch generator operates independently in its own domain (time or frequency), and its output is then passed to the further processing stage. This separation allows different patching algorithms to be implemented without affecting the unified further processing pipeline.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patched signal serves as an intermediary between the patch generator and the further processing stage. The patch generator produces a patched signal that is then fed into the standard further processing pipeline, allowing the two functions to be independent yet coordinated through this intermediate representation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If spectral band replication is performed without flexible algorithm selection, then the processing is straightforward, but audio quality degrades due to inability to optimize for different signal portions

Engineering Contradiction:

Improveaudio quality in spectral band replicationVSAvoidcontrol information for algorithm selection

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system applies different patching algorithms to different portions of the audio signal based on local characteristics. Control information specifies which algorithm to use for different time portions or frequency regions, allowing optimal processing for each local segment while maintaining overall system coherence.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10522168B2Audio signal synthesizer and audio signal encoder

Publication Date: 2019.12.31 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

AI summary

An audio signal synthesizer generates a synthesis audio signal having a first frequency band and a second synthesized frequency band derived from the first frequency band and comprises a patch generator, a spectral converter, a raw signal processor and a combiner. The patch generator performs at least two different patching algorithms, each patching algorithm generating a raw signal. The patch generator is adapted to select one of the at least two different patching algorithms in response to a control information. The spectral converter converts the raw signal into a raw signal spectral representation. The raw signal processor processes the raw signal spectral representation in response to spectral domain spectral band replication parameters to obtain an adjusted raw signal spectral representation.