Adaptive Sound Coding for High-Frequency Energy Variations
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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 potentially artificial-sounding decoded signals.
Innovation Solution
A coding method that selects between different coding processing types 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 applies dynamics by making the coding method selectable and adaptable based on the input signal's characteristics. The system dynamically chooses between spectral envelope-based coding and average energy differential coding depending on whether the signal has steep or gentle spectral ascents and descents, allowing optimal performance across different signal types.
Solution Approach 2:
The patent changes the coding parameter (coding method type) based on the spectral characteristics of the input signal. By detecting whether spectral ascents and descents are steep or gentle, the system adjusts the coding approach to match the signal properties, thereby resolving the contradiction between coding efficiency and adaptability.
2Productivity
If a single coding method is used for all signals, then device complexity is reduced, but coding efficiency deteriorates for certain signal types
Solution Approach 1:
The patent applies local quality by applying different coding methods to different portions of the signal spectrum based on local characteristics. Specifically, spectral envelope-based coding is applied when spectral ascents and descents are steep, while average energy differential coding is applied when they are gentle, optimizing efficiency for each local condition.
3Productivity
If variable-length coding on average energy differential is used, then coding efficiency is improved for signals with gentle spectral ascents and descents, but coding efficiency deteriorates for signals with high spectral concentration
Solution Approach 1:
The patent changes the coding parameter (coding method type) based on the spectral characteristics of the input signal. By detecting whether spectral ascents and descents are steep or gentle, the system adjusts the coding approach to match the signal properties, thereby resolving the contradiction between coding efficiency and adaptability.
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.