Scalable Audio Coding with Dynamic Layer Control
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Solution Overview
Problem
Existing scalable coding techniques for speech signals do not optimally maintain sound quality under varying channel conditions, as they either fix the relationship between lower and higher layers or primarily adjust bit rates to prevent buffer overflow, leading to suboptimal coding in certain conditions.
Innovation Solution
A coding apparatus and method that dynamically adjusts the coding scheme for higher layers based on the coding results of lower layers, using a configuration with a base layer coding section, enhancement layer decoding section, and an enhancement layer control section to encode and decode signals in a scalable manner, ensuring optimal quality by switching coding methods according to coding parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed relationship between lower layer and higher layer is used in scalable coding, then the coding structure is simple, but the speech quality is not optimal under certain limited conditions
Solution Approach 1:
The patent applies dynamics by making the relationship between lower layer and higher layer variable rather than fixed. The higher layer control section dynamically adjusts the coding parameters of the higher layer based on the coding results from the lower layer, allowing the system to adapt to different speech signal characteristics and channel conditions, thereby optimizing speech quality across various scenarios.
Solution Approach 2:
The patent changes parameters by adjusting higher layer coding parameters based on lower layer coding results. Specifically, the higher layer control section modifies coding parameters such as bit allocation, quantization levels, or coding modes in the higher layer according to the performance and characteristics observed in the lower layer, enabling optimal speech quality under different conditions.
2Reliability
If bit rate adjustment is primarily used to prevent buffer overflow, then transmission buffer management is improved, but speech quality is not optimal when channel is not congested
Solution Approach 1:
The patent extends parameter changes beyond bit rate adjustment to include multiple higher layer coding parameters. When the channel is not congested, the system adjusts these additional parameters (such as quantization precision, coding mode, or filter coefficients) to optimize speech quality, rather than solely relying on bit rate control for buffer management.
Solution Approach 2:
The patent implements feedback by having the higher layer control section continuously monitor lower layer coding results and channel conditions, then adjust higher layer parameters accordingly. This closed-loop control ensures that when channel congestion is low, the system can allocate more resources to quality enhancement, and when congestion occurs, it can prioritize buffer management.
3Adaptability or versatility
If scalable coding with multiple layers is used, then adaptability to different channel conditions is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing the higher layer control section to perform multiple functions: it monitors lower layer coding results, analyzes channel conditions, determines optimal parameter settings, and controls higher layer coding. This multi-functional approach consolidates what could be separate complex modules into a unified control mechanism, managing complexity while maintaining adaptability.
Data Source
AI summary
A coding device is provided with features in which optimum coding in a higher layer is flexibly carried out based on a coding result of a lower layer and a quality audio signal in limited circumstances is served to users. In this coding device, a basic layer coding unit codes an input signal to generate a basic layer information source code and outputs a linear prediction coefficient (LPC) and a quantum LPC, which are parameters calculated at coding, to an expanded layer control unit. A basic layer decoding unit decodes the basic layer information source code. An adding unit reverses a polarity of a basic layer decoded signal, adds the same to the input signal, and calculates a difference signal. The expanded layer control unit generates expanded layer mode information indicative of a coding mode in an expanded layer based on the LPC and the quantum LPC. An expanded layer coding unit codes the difference signal obtained from the adding unit under control of the expanded layer control unit.