Stereo Sound Encoding Using Correlated Parameter Quantization
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Solution Overview
Problem
Existing speech coding methods for stereo signals, such as those employing inter-channel pitch prediction, suffer from low coding efficiency due to separate encoding of inter-channel prediction parameters like delay and gain, which limits the quality of stereo speech communication.
Innovation Solution
A speech coding apparatus that calculates and quantizes prediction parameters, specifically delay difference and amplitude ratio, to efficiently encode stereo signals by utilizing correlation between channels, thereby improving coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If inter-channel prediction parameters (delay and gain) are separately encoded between channels, then stereo speech encoding can be implemented, but coding efficiency is not high
Solution Approach 1:
The patent combines the encoding of delay difference and amplitude ratio into a unified quantization process. Instead of separately encoding delay and gain parameters as in prior art, the invention merges these parameters into a joint quantization framework that exploits their correlation, thereby improving coding efficiency while reducing the overall complexity of the encoding system.
Solution Approach 2:
The patent transforms the parameter representation by changing from separate delay and gain parameters to correlated delay difference and amplitude ratio parameters. This parameter transformation enables more efficient coding by capturing the statistical correlation between channels, allowing for reduced bit rate while maintaining stereo speech quality.
2Quantity of substance
If separate encoding of inter-channel prediction parameters is used, then stereo signal encoding is achieved, but bit rate efficiency deteriorates
Solution Approach 1:
The patent changes the parameter encoding approach by introducing correlated quantization of delay difference and amplitude ratio. This parameter transformation allows for more compact representation of stereo information, improving bit rate efficiency while preserving the essential spatial characteristics of the stereo signal through the correlation between parameters.
Solution Approach 2:
The patent creates a composite encoding structure that combines delay difference and amplitude ratio into a unified quantization scheme. This composite approach leverages the correlation between parameters to achieve more efficient bit rate utilization while maintaining complete stereo information representation.
Data Source
AI summary
A sound encoder for efficiently encoding stereophonic sound. A prediction parameter analyzer determines a delay difference D and an amplitude ratio g of a first-channel sound signal with respect to a second-channel sound signal as channel-to-channel prediction parameters from a first-channel decoded signal and a second-channel sound signal. A prediction parameter quantizer quantizes the prediction parameters, and a signal predictor predicts a second-channel signal using the first decoded signal and the quantization prediction parameters. The prediction parameter quantizer encodes and quantizes the prediction parameters (the delay difference D and the amplitude ratio g) using a relationship (correlation) between the delay difference D and the amplitude ratio g attributed to a spatial characteristic (e.g., distance) from a sound source of the signal to a receiving point.