High-Frequency Band Extension Coding with Dynamic Sub-Band Allocation
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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 low resolution and bit allocation constraints, which affect the quality and efficiency of audio signal representation.
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 improved high-frequency band extension.
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 of high-frequency signal representation deteriorates due to low bit allocation
Solution Approach 1:
The patent segments the high-frequency band into multiple sub-bands and processes each sub-band separately with dedicated bit allocation. This allows finer control over resolution in different frequency regions while maintaining overall coding efficiency, directly addressing the contradiction between efficient compression and high-frequency resolution.
Solution Approach 2:
The patent applies local quality enhancement by allocating different bit rates to different sub-bands based on their importance and characteristics. Critical sub-bands receive higher resolution encoding while less critical areas use lower bit rates, thus improving overall high-frequency representation without sacrificing coding efficiency.
2Productivity
If a large number of bits are assigned to low-frequency band to improve coding efficiency, then overall audio quality improves, but the bandwidth extension capability for high-frequency band deteriorates due to bit allocation constraints
Solution Approach 1:
The patent implements dynamic bit allocation that adapts to the characteristics of the audio signal. The system dynamically adjusts the number of bits allocated to low-frequency and high-frequency bands based on signal complexity, spectral content, and bandwidth extension requirements, enabling flexible resource distribution that maintains both coding efficiency and bandwidth extension capability.
Solution Approach 2:
The patent changes the allocation parameter (bit rate distribution) based on signal conditions and bandwidth extension needs. By varying bit allocation dynamically according to signal characteristics and target bandwidth requirements, the system optimizes the trade-off between overall coding efficiency and high-frequency bandwidth extension capability.
Data Source
AI summary
A method and apparatus for performing coding and decoding for high-frequency bandwidth extension. The decoding apparatus may include: a mode checking unit to check mode information of each of frames included in a bitstream; a first core decoding unit to perform code excited linear prediction (CELP) decoding on a CELP coded frame, when a core coding mode of a low-frequency signal indicates a CELP coding mode; a first extension decoding unit to generate a decoded signal of a high-frequency band by using at least one of a result of the performing the CELP decoding and an excitation signal of the low-frequency signal; a second core decoding unit to perform audio decoding on an audio coded frame, when the core coding mode indicates an audio coding mode; and a second extension decoding unit to generate a decoded signal of the high-frequency band by performing frequency-domain (FD) extension decoding.