Frequency-Domain Bandwidth Extension for High-Frequency Audio Coding
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Solution Overview
Problem
Current audio signal coding technologies, such as spectral band replication (SBR), face limitations in efficiently extending the bandwidth of high-frequency bands due to their sensitivity to frequency fine structures and bit allocation restrictions, leading to suboptimal coding efficiency.
Innovation Solution
A method and apparatus that includes a down-sampler, core coder, frequency transformer, and extension coder to perform bandwidth extension coding by generating a base signal in the frequency domain, estimating an energy control factor, extracting and controlling energy, and quantizing it using a base signal and artificial signal generation techniques, allowing for efficient extension of high-frequency band bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spectral band replication (SBR) is used to extend high-frequency bandwidth, then coding efficiency is improved, but the resolution with regard to high-frequency signal is reduced
Solution Approach 1:
The patent segments the high-frequency signal processing into two distinct parts: (1) SBR-based bandwidth extension for efficiency, and (2) separate processing of high-frequency components to preserve resolution. The extension coder extracts and processes high-frequency components independently while maintaining their fine structures, allowing both coding efficiency and signal resolution to be optimized simultaneously.
Solution Approach 2:
The patent applies different processing qualities to different frequency regions. Low-frequency bands use standard SBR processing for efficiency, while high-frequency bands receive enhanced processing that preserves fine structures. This local differentiation allows the system to optimize coding efficiency in less critical regions while maintaining high resolution where it matters most.
2Productivity
If a large number of bits are assigned to low-frequency band to eliminate bit allocation restrictions, then coding efficiency is improved, but the bandwidth extension of high-frequency band is limited
Solution Approach 1:
The patent extracts high-frequency components from the original signal and processes them separately through the extension coder. This extraction allows the system to allocate bits more effectively - using SBR for general bandwidth extension while dedicating specific resources to preserve and enhance extracted high-frequency components, thereby extending high-frequency bandwidth without compromising overall coding efficiency.
Solution Approach 2:
The patent transitions from time-domain processing to frequency-domain processing for high-frequency components. By transforming the signal and processing high-frequency bands in the frequency domain, the system can allocate bits more strategically across different frequency regions, enabling extended high-frequency bandwidth while maintaining efficient overall coding.
Data Source
AI summary
A method and apparatus for performing coding and decoding for high-frequency bandwidth extension. The coding apparatus may down-sample an input signal, perform core coding on the down-sampled input signal, perform frequency transformation on the input signal, and perform bandwidth extension coding by using a base signal of the input signal in a frequency domain.