Spatial Synthesis Matrix Coefficients for Negative Interchannel Correlation
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Solution Overview
Problem
The MPEG Surround standard's decoding technique for multichannel audio signals with channels in phase opposition results in poor spatial reconstruction and audible artifacts due to its limitations with negative interchannel correlations, particularly when interchannel correlation approaches -1, leading to excessive reliance on the decorrelated signal and loss of waveform control.
Innovation Solution
A method and device for spatially synthesizing a sum signal using a synthesis matrix with coefficients determined by a quantitative function that minimizes the quantity of decorrelated signal in output signals, addressing the issue of negative interchannel correlations by optimizing the synthesis matrix coefficients based on energy and interchannel correlation parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the MPEG Surround standard's decoding technique is used for multichannel audio signals with negative interchannel correlations, then the spatial reconstruction quality deteriorates and audible artifacts are generated, but the conventional coding structure is maintained
Solution Approach 1:
The patent changes the parameters of the synthesis matrix coefficients based on the interchannel correlation value. When the interchannel correlation is negative, the synthesis matrix coefficients are adjusted to minimize the quantity of decorrelated signal used, thereby maintaining waveform integrity and avoiding audible artifacts while preserving spatial reconstruction quality.
2Adaptability or versatility
If the quantity of decorrelated signal is increased to handle negative interchannel correlations, then the waveform control is lost, but the interchannel correlation is addressed
Solution Approach 1:
The patent introduces a feedback mechanism where the synthesis matrix coefficients are determined based on the interchannel correlation parameter. The system continuously adjusts the coefficients to minimize the decorrelated signal quantity while maintaining the required interchannel correlation, thereby preserving waveform integrity even when handling negative correlations.
3Stability of the object's composition
If the synthesis matrix coefficients are optimized to minimize decorrelated signal quantity, then the waveform integrity is maintained, but the complexity of coefficient determination increases
Solution Approach 1:
The patent simplifies the coefficient determination process by establishing a direct relationship between the interchannel correlation parameter and the synthesis matrix coefficients. The coefficients are determined based on the interchannel correlation value within specific ranges, avoiding complex optimization algorithms while maintaining waveform integrity and minimizing decorrelated signal usage.
Data Source
AI summary
A method and associated device are provided for spatial synthesis of a sum signal to obtain at least two output signals, the sum signal as well as the spatialization parameters being output from a parametric coding by matrixing of an original multi-channel signal. The method comprises: decorrelation of the sum signal to obtain a decorrelated signal; applying a synthesis matrix, whose coefficients depend on the spatialization parameters, to the decorrelated signal and to the sum signal to obtain said output signals, wherein for at least one range of value of at least one spatialization parameter, the coefficients of the synthesis matrix are determined according to a criterion of minimizing a quantitative function, relating to the quantity of decorrelated signal in each of the output signals obtained by applying the synthesis matrix.