Adaptive Sound Signal Coding by High-Frequency Energy Switching
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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 the appropriate coding processing for each frame of a sound signal based on the energy of high-frequency components and spectral characteristics, switching between different coding techniques such as linear prediction coefficient coding and variable-length coding of average energy differentials to adapt to varying signal characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single coding method is used for all frames, then the coding process is simple, but the coding efficiency is insufficient for signals with varying characteristics
Solution Approach 1:
The patent implements dynamic coding by selecting different coding methods (first coding method using spectral envelope or second coding method using average energy differential) based on the characteristics of each frame. The selection is made by comparing high-frequency energy levels and spectral characteristics, allowing the system to adapt to varying signal conditions and optimize coding efficiency for each frame while managing overall complexity through structured decision logic.
2Productivity
If coding method switching is enabled, then coding efficiency improves for varying signal characteristics, but processing complexity increases
Solution Approach 1:
The system dynamically selects between coding methods by evaluating high-frequency energy levels and spectral characteristics of each frame. When high-frequency energy exceeds a threshold, the first coding method using spectral envelope is selected; otherwise, the second coding method using average energy differential is used. This dynamic adaptation improves coding efficiency for varying signal characteristics while maintaining manageable processing complexity through clear selection criteria.
Solution Approach 2:
The patent changes coding parameters based on signal characteristics by adjusting the coding method selection according to high-frequency energy levels and spectral properties. This parameter change approach allows the system to optimize coding efficiency by matching the coding method to the current signal state, thereby improving overall performance without requiring overly complex processing mechanisms.
3Adaptability or versatility
If high-frequency energy threshold comparison is performed, then appropriate coding method selection is achieved, but additional processing steps are required
Solution Approach 1:
The patent uses high-frequency energy threshold comparison as a key parameter change criterion for coding method selection. By comparing the high-frequency energy level against a predetermined threshold, the system accurately determines whether to use the spectral envelope-based coding method or the average energy differential method. This parameter-based selection approach improves adaptability while keeping processing steps manageable through a clear decision threshold.
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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.