Audio Signal Synthesis With Dynamic Patching for Flexible SBR
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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 perceptual degradation and limitations in bandwidth extension for high-quality audio transmission.
Innovation Solution
An audio signal synthesizer that performs at least two different patching algorithms, selecting the appropriate algorithm based on control information for specific time portions, and processes the raw signals in independent domains to generate a synthesis audio signal, allowing for flexible application of patching algorithms and efficient spectral band replication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single patching algorithm is used for all audio signals as in MPEG-4 standard, then implementation is simple, but adaptability to different audio signals and coding schemes is poor
Solution Approach 1:
The patent implements dynamic selection of patching algorithms based on signal characteristics. The system analyzes the audio signal properties and dynamically chooses the most appropriate patching algorithm (e.g., spectral copying, spectral transformation, or harmonic regeneration) rather than using a fixed single algorithm, thereby achieving adaptability while managing complexity through conditional logic
Solution Approach 2:
The patent changes the parameter of algorithm selection based on signal characteristics. By monitoring parameters such as signal type (speech/music), bandwidth requirements, and coding scheme, the system adjusts which patching algorithm is applied, enabling adaptability to different audio scenarios without requiring a completely complex system architecture
2Reliability
If spectral band replication is performed without flexible algorithm selection, then processing is straightforward, but perceptual quality deteriorates
Solution Approach 1:
The patent applies different patching algorithms to different portions of the audio signal based on local characteristics. For example, speech segments may use one algorithm while music segments use another, and different frequency bands may be processed differently. This localized approach improves perceptual quality by matching the processing method to the specific signal characteristics of each segment
Solution Approach 2:
The patent segments the audio signal processing into multiple stages and paths. The signal is divided into different types (speech, music, transient) and each segment is processed by the most suitable patching algorithm. This segmentation allows the system to achieve high perceptual quality for each segment type while keeping the overall processing complexity manageable through modular architecture
3Reliability
If bandwidth extension is performed with fixed processing methods, then implementation is simple, but audio quality and naturalness are limited
Solution Approach 1:
The patent creates a universal bandwidth extension system that can handle multiple types of audio signals (speech, music, arbitrary signals) and multiple coding schemes through a unified framework. The system uses a set of universal patching algorithms that can be selectively applied based on the input signal characteristics, achieving high audio quality across different applications while maintaining a relatively simple overall implementation structure
Data Source
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.