Audio Signal Synthesis with Flexible SBR Patching Domains
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Solution Overview
Problem
Current audio coding technologies, such as the MPEG-4 standard, lack flexibility in spectral band replication (SBR) methods, leading to inefficient implementation and perceptual degradation due to the strong link between patching and further processing operations in the same filterbank domain.
Innovation Solution
The solution involves performing patching and further processing operations in independent domains, allowing for the flexible application of different patching algorithms and optimizing each component separately, thereby enabling efficient and high-quality audio signal synthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If patching and further processing operations are performed in the same filterbank domain, then implementation is simplified, but flexibility to apply different patching algorithms is reduced
Solution Approach 1:
The patent segments the audio processing system into two independent domains: a filterbank domain for patching operations and a spectral domain for further processing operations. This separation allows different patching algorithms to be applied in the filterbank domain while maintaining the same spectral processing pipeline, thereby resolving the contradiction between implementation simplicity and algorithmic flexibility.
Solution Approach 2:
The patent introduces a domain transformation dimension by converting signals between filterbank domain and spectral domain. This allows patching to occur in one domain (filterbank) while processing occurs in another domain (spectral), enabling flexibility in algorithm selection without complicating the overall implementation structure.
2Adaptability or versatility
If multiple patching algorithms are implemented with independent domains, then flexibility and audio quality are improved, but device complexity increases
Solution Approach 1:
By segmenting the processing into distinct domains (filterbank for patching, spectral for processing), the patent allows multiple patching algorithms to be implemented as separate modules that can be selected based on signal characteristics, managing complexity through modular design while maintaining flexibility.
Solution Approach 2:
The patent implements dynamic selection of patching algorithms based on signal analysis (e.g., pulse-train-like vs. non-pulse-train-like signals). This dynamic approach allows the system to adaptively choose the most appropriate algorithm for each signal portion, improving audio quality without requiring all algorithms to be simultaneously active, thus managing device complexity.
3Device complexity
If a single patching algorithm is used for all audio signals, then device complexity is reduced, but audio quality and adaptability deteriorate
Solution Approach 1:
The patent applies local quality by analyzing local signal characteristics (e.g., pulse-train-like vs. non-pulse-train-like portions) and applying different patching algorithms to different portions of the audio signal. This ensures optimal audio quality for each signal type while managing overall system complexity through selective algorithm application.
Solution Approach 2:
The system dynamically adapts the patching algorithm selection based on real-time signal analysis, switching between different algorithms (e.g., switched transposer for pulse-train-like signals, frequency domain transposer for non-pulse-train-like signals) to maintain high audio quality across diverse audio content while keeping the system design manageable.
Data Source
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AI summary
In accordance with a first aspect of the invention, 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. The audio signal synthesizer comprises a patch generator, a spectral converter, a raw signal processor and a combiner. The patch generator performs at least two different patching algorithms, wherein each patching algorithm generates a raw signal having signal components in the second synthesized frequency band using an audio signal having signal components in the first frequency band. The patch generator is adapted to select one of the at least two different patching algorithms in response to a control information for a first time portion and the other of the at least two different patching algorithms in response to the control information for a second time portion different from the first time portion to obtain the raw signal for the first and the second time portion. 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. The combiner combines an audio signal having signal components in the first band or a signal derived from the audio signal with the adjusted raw signal spectral representation or with a further signal derived from the adjusted raw signal spectral representation to obtain the synthesis audio signal.