Stereo Downmix Weighting Using Correlation and Delay Cues
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Solution Overview
Problem
Existing techniques for obtaining a monaural signal from a two-channel sound signal are not optimized for signal processing, such as encoding, due to low similarity between the averaged left and right channel signals, leading to inefficient coding.
Innovation Solution
A sound signal downmixing method that includes a delayed crosstalk addition step, left-right relationship information acquisition, and a downmixing step to obtain a monaural signal by weighted addition based on correlation and preceding channel information, followed by monaural and stereo encoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a monaural signal is obtained by averaging left and right channel sound signals, then the monaural signal can be obtained simply, but the signal is not useful for encoding processing
Solution Approach 1:
The patent changes the parameters of the monaural signal by applying delayed crosstalk addition and weighted addition based on left-right correlation values. Instead of simple averaging, the system processes the signal through these transformations to create a monaural signal that preserves encoding utility while maintaining simplicity in the overall process.
Solution Approach 2:
The patent introduces delayed crosstalk-added signals as intermediary elements. These signals serve as mediators between the original left and right channel signals and the final monaural signal, enabling the system to extract useful information for encoding processing while maintaining signal quality.
2Productivity
If prediction signals with optimized delay and amplitude ratio are used, then coding efficiency of each channel is improved, but the monaural local decoded signal is not useful for signal processing
Solution Approach 1:
The patent segments the signal processing into distinct components: delayed crosstalk addition, left-right relationship information acquisition, and downmixing. This segmentation allows each component to serve its specific function - improving coding efficiency while simultaneously producing a useful monaural signal for encoding processing.
Solution Approach 2:
The patent creates a system where the downmixing process serves multiple functions simultaneously: it generates the monaural signal for encoding processing, optimizes coding efficiency through weighted addition based on correlation values, and produces signals suitable for both monaural and stereo encoding.
3Device complexity
If simple averaging is used to obtain monaural signal, then processing is simple, but encoding efficiency is low
Solution Approach 1:
The patent introduces dynamic elements through the use of variable weight values in the weighted addition process. The weight values are determined by left-right correlation values, which change based on the signal characteristics. This dynamic adjustment optimizes encoding efficiency while keeping the overall processing structure relatively simple.
Solution Approach 2:
The patent changes processing parameters by introducing delayed crosstalk addition with specific weight values (absolute value smaller than 1) and subsequent weighted addition based on correlation values. These parameter changes enable the system to achieve high encoding efficiency without significantly increasing processing complexity.
Data Source
AI summary
A sound signal downmixing method includes a step of obtaining, for each of two channels, a signal obtained by adding an input sound signal of one channel to a signal obtained by delaying an input sound signal of the other channel and multiplying the delayed input sound signal by a weight value as a delayed crosstalk-added signal of the one channel, a step of obtaining preceding channel information and a left-right correlation value, and step of obtaining a downmix signal by performing weighted addition on the input sound signals of the two channels based on the left-right correlation value and the preceding channel information such that more of a signal derived from an input sound signal of a preceding channel among the signals derived from the input sound signals of the two channels is included as the left-right correlation value becomes larger.