Stereo Signal Decoding Device Frame Loss Smoothing
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Solution Overview
Problem
Existing multi-channel encoding/decoding schemes, such as the M/S encoding/decoding scheme, suffer from sound quality deterioration due to frame loss, particularly because they lack effective methods to smooth decoded signals in the unit of sample and conceal spatial characteristics accurately.
Innovation Solution
A decoding apparatus and method that receive encoded monaural and difference signals, detect variations over time, smooth the decoded difference signal using appropriate coefficients, and compute the decoded stereo signal to alleviate abrupt changes and improve sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If M/S encoding scheme is used for stereo signal transmission, then transmission efficiency is improved by removing correlation between channels, but sound quality deteriorates when frame loss occurs due to inability to smooth decoded signals in unit of sample
Solution Approach 1:
The patent segments the decoding process into separate components: decoding the monaural signal, decoding the difference signal, and then combining them. This segmentation allows independent optimization of each component and enables targeted smoothing of the difference signal to address frame loss issues without compromising the overall transmission efficiency benefits of M/S encoding.
Solution Approach 2:
The patent introduces a smoothing coefficient as a new parameter that can be dynamically adjusted based on transmission conditions. By changing this parameter to control the degree of smoothing applied to the difference signal, the system can adapt to frame loss conditions and maintain sound quality while preserving the efficiency advantages of the M/S encoding scheme.
2Device complexity
If parameter level concealment process is performed for erroneous frames, then processing complexity is reduced, but spatial characteristics cannot be concealed with high precision
Solution Approach 1:
The patent applies local quality by treating the difference signal separately from the monaural signal and applying smoothing specifically to the difference signal component. This localized approach allows precise control over spatial characteristic concealment in the difference signal while keeping the overall processing complexity manageable by avoiding comprehensive reprocessing of all signal components.
Solution Approach 2:
The patent performs preliminary decoding of both the monaural and difference signals before combining them, and applies smoothing to the difference signal in advance. This preliminary action allows the system to prepare cleaned-up signal components before final reconstruction, improving spatial characteristic concealment precision without requiring complex real-time concealment processes.
3Ease of manufacture
If stepwise muting is performed at parameter level for each frame, then implementation is simplified, but detailed muting in unit of sample cannot be performed
Solution Approach 1:
The patent introduces dynamic smoothing that operates at the sample level rather than fixed stepwise muting at the frame level. The smoothing coefficient can be dynamically adjusted based on the specific conditions of each sample, enabling precise control over muting behavior at the sample level while maintaining implementation feasibility through a relatively simple smoothing operation.
Data Source
AI summary
A decoding device reduces abrupt changes in the number of channels in a decoded signal when transmission errors occur as a result of lost frames in an encoding/decoding system for multichannel signals. In the device, a demultiplexer receives an encoded monaural signal and an encoded differential signal and detects change over time in the received encoded differential signal. An M signal decoder decodes the encoded monaural signal and obtains a decoded monaural signal. An S signal decoder decodes the encoded differential signal and obtains a decoded differential signal. A smoothing unit performs smoothing on the decoded differential signal by means of a computation involving the decoded differential signal and coefficients corresponding to the change over time detected by the demultiplexer. An L/R signal computation unit computes a decoded stereo signal from the decoded monaural signal and the smoothed decoded differential signal.