Speech Audio Coding with Group-Based Bit Allocation
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Solution Overview
Problem
Existing speech/audio coding techniques do not efficiently allocate bits based on input signal characteristics, limiting the improvement of sound quality.
Innovation Solution
A speech/audio coding apparatus and method that transforms an input signal into a frequency domain, estimates energy envelopes, groups them, and allocates bits on a group-by-group basis to subbands, allowing for efficient bit allocation and improved sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transform coding is used to encode full band audio signal, then frequency-domain transformation enables precise mapping with auditory characteristics, but existing bit allocation schemes do not efficiently allocate bits based on input signal characteristics
Solution Approach 1:
The patent applies dynamics by making the bit allocation scheme adaptive to input signal characteristics. The system dynamically adjusts bit allocation based on detected signal features (transient vs. stationary frames, spectral envelope, energy distribution), transforming a static allocation method into a dynamic one that responds to varying signal conditions, thereby improving allocation efficiency while maintaining precise auditory mapping
Solution Approach 2:
The patent changes parameters by introducing multiple signal characteristics (transient detection results, spectral envelope parameters, energy distribution metrics) as variables in the bit allocation process. By adjusting bit allocation based on these parameter variations, the system optimizes the balance between maintaining auditory mapping precision and improving coding efficiency for different signal types
2Manufacturing precision
If more quantization bits are allocated to perceptually important bands, then overall sound quality is improved, but complex bit allocation schemes are required to determine optimal distribution
Solution Approach 1:
The patent applies preliminary action by detecting signal characteristics (transient frames, spectral envelope, energy distribution) before performing bit allocation. This pre-analysis of input signal features enables the system to prepare an optimized bit distribution strategy in advance, simplifying the subsequent allocation process while ensuring high sound quality through perceptually-driven allocation
Solution Approach 2:
The patent implements feedback by using detected signal characteristics (transient detection, spectral envelope analysis, energy measurement) to inform and adjust the bit allocation decision. This closed-loop approach where signal analysis results feed into allocation optimization simplifies the overall system by using measurable parameters to guide bit distribution, achieving high sound quality without excessive complexity
3Productivity
If transient detection and spectral analysis are performed to optimize bit allocation, then bit allocation efficiency improves, but processing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the frequency spectrum into multiple bands and analyzing each band's characteristics separately (spectral envelope, energy distribution). This segmented approach to signal analysis enables efficient bit allocation per band based on local characteristics, improving overall allocation efficiency while managing processing complexity through structured, modular analysis of signal components
Data Source
AI summary
Provided are a voice audio encoding device, voice audio decoding device, voice audio encoding method, and voice audio decoding method that efficiently perform bit distribution and improve sound quality. Dominant frequency band identification unit identifies a dominant frequency band having a norm factor value that is the maximum value within the spectrum of an input voice audio signal. Dominant group determination units and non-dominant group determination unit group all sub-bands into a dominant group that contains the dominant frequency band and a non-dominant group that contains no dominant frequency band. Group bit distribution unit distributes bits to each group on the basis of the energy and norm variance of each group. Sub-band bit distribution unit redistributes the bits that have been distributed to each group to each sub-band in accordance with the ratio of the norm to the energy of the groups.