Adaptive Sound Coding by Frame-Wise Frequency Selection
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Solution Overview
Problem
Existing sound signal coding methods are inefficient as they fail to consistently achieve optimal coding regardless of the characteristics of the input sound signal, leading to artificial-sounding decoded signals.
Innovation Solution
A coding method that selects between different coding processes in the frequency domain based on the energy of high-frequency components and the spectral characteristics of the input sound signal, using either spectral envelope-based coding or variable-length coding on average energy differentials, to adapt to varying signal characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spectral envelope-based coding is used, then coding efficiency is improved for signals with steep spectral ascents and descents, but coding efficiency deteriorates for signals with gentle spectral ascents and descents
Solution Approach 1:
The patent implements dynamic selection between two different coding methods (spectral envelope-based coding and average energy differential coding) based on the characteristics of the input sound signal. The system evaluates spectral characteristics and automatically switches between coding methods to optimize performance for different signal types, making the coding system adaptive rather than static.
Solution Approach 2:
The patent changes the coding parameter set based on signal characteristics. When spectral ascents and descents are steep, it uses spectral envelope parameters; when they are gentle, it uses average energy differential parameters. This parameter adaptation allows the system to achieve high coding efficiency across diverse signal characteristics.
2Productivity
If average energy differential variable-length coding is used, then coding efficiency is improved for signals with gentle spectral ascents and descents, but coding efficiency deteriorates for signals with steep spectral ascents and descents
Solution Approach 1:
The system dynamically selects the appropriate coding method based on real-time analysis of spectral characteristics. For signals with gentle spectral ascents and descents, it switches to average energy differential variable-length coding to achieve high efficiency, while maintaining the capability to switch to spectral envelope-based coding when needed.
Solution Approach 2:
The patent adapts the coding parameters by selecting different parameter sets (average energy differentials versus spectral envelope coefficients) based on the input signal characteristics, enabling optimal coding efficiency for gentle spectral variations while maintaining versatility through conditional switching.
3Device complexity
If a fixed coding method is used for all frames, then device complexity is reduced, but coding efficiency deteriorates for certain signal characteristics
Solution Approach 1:
The patent introduces dynamic method selection with automatic switching between two coding approaches based on spectral analysis of the input signal. This dynamic adaptation increases coding efficiency for diverse signal characteristics while keeping the overall system structure relatively simple through rule-based selection criteria.
Solution Approach 2:
The system changes coding parameters adaptively by selecting between spectral envelope parameters and average energy differential parameters based on signal characteristics. This parameter adaptation improves coding efficiency without requiring complex device architecture, as the selection is based on straightforward spectral analysis.
Data Source
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AI summary
An object is to provide a coding technology that efficiently codes an input sound signal irrespective of the characteristics thereof and can obtain a decoded sound signal that sounds less artificial to a listener. There is provided a coding method that codes an input sound signal frame by frame of a predetermined time segment by a selected coding processing from a plurality of types of coding processing in the frequency domain, the coding method that makes it possible for a selection unit 380 to select coding processing which is different from the coding processing of the preceding frame as coding processing of the present frame if at least one of the magnitude of the energy of high frequency components of the input sound signal of the preceding frame and the magnitude of the energy of high frequency components of the input sound signal of the present frame is smaller than or equal to a predetermined threshold value.