Spectral Domain Patch Generator for Audio Bandwidth Extension
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Solution Overview
Problem
Existing audio codecs face limitations in bandwidth extension, particularly due to the lack of adaptability in patching algorithms, which leads to blocking artifacts and reduced flexibility when switching between different domains, resulting in suboptimal quality and complexity in audio signal processing.
Innovation Solution
The implementation of an apparatus and method that allows switching between multiple spectral domain patching algorithms within the spectral domain, using a patching control signal to select the appropriate algorithm for different time portions of an audio signal, thereby reducing complexity and maintaining perceptual quality by performing bandwidth extension with a maximum frequency of at least four times the crossover frequency in the core frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single patching algorithm is used in spectral band replication, then the device complexity is reduced, but the adaptability to different signal characteristics is worsened
Solution Approach 1:
The patent implements dynamic switching between different patching algorithms (time-domain and spectral-domain) based on signal characteristics. The system selects the appropriate algorithm in real-time, making the processing adaptable to different input signals while maintaining reasonable complexity through controlled algorithm selection.
Solution Approach 2:
The patent changes the processing domain parameter (time-domain vs. spectral-domain) based on signal characteristics. By switching between different domains and algorithms according to signal properties, the system achieves adaptability without permanently increasing device complexity.
2Adaptability or versatility
If multiple patching algorithms are switched between different domains, then the adaptability is improved, but blocking artifacts are generated and device complexity increases
Solution Approach 1:
The patent segments the audio signal processing into different domains (time-domain and spectral-domain) and applies appropriate patching algorithms to each segment based on signal characteristics. This segmentation allows adaptive processing while managing the transition between domains to reduce blocking artifacts.
Solution Approach 2:
The patent uses an intermediary selection mechanism that chooses between time-domain and spectral-domain patching algorithms based on signal characteristics. This intermediary layer manages the complexity by intelligently selecting the appropriate algorithm rather than implementing all algorithms simultaneously.
3Manufacturing precision
If spectral domain patching is used for bandwidth extension, then the manufacturing precision of audio quality is improved, but the device complexity increases
Solution Approach 1:
The patent implements a universal patching system that can operate in both time-domain and spectral-domain, selecting the most appropriate domain based on signal characteristics. This multi-functionality approach improves audio quality across different signal types while managing complexity through adaptive selection rather than permanent implementation of all features.
Data Source
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.