Adaptive Audio Downmix Matrix Using Eigenvector Subspace Selection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional audio signal processing methods are unable to optimally and flexibly reproduce multichannel audio on legacy playback devices without prior information about the reproduction layout, limiting the ability to support an arbitrary number of output channels.
Innovation Solution
An audio signal processing apparatus and method that uses a downmix matrix comprising a primary downmix matrix and an auxiliary downmix matrix, where the auxiliary downmix matrix is determined by computing eigenvectors of a covariance matrix and selecting eigenvectors based on subspace angles to adaptively reproduce audio signals with an arbitrary number of channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed downmix matrix is used to reproduce multichannel audio on legacy playback devices, then the reproduction is simple and deterministic, but the system cannot adapt to arbitrary numbers of output channels without prior information
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed downmix matrix to an adaptive one that changes based on the actual playback configuration. The system dynamically determines the downmix matrix using eigenvectors of the covariance matrix, allowing it to adapt to any number of output channels (M) without requiring prior information about the specific configuration.
Solution Approach 2:
The system performs self-service by automatically determining the appropriate downmix matrix based on the playback device's capabilities. The auxiliary downmix matrix is computed using eigenvectors of the covariance matrix, enabling the system to self-configure for different channel configurations (e.g., stereo to 3.0, stereo to 8.2) without external intervention or prior information.
2Ease of operation
If prior information about reproduction layout is required, then the downmix matrix can be pre-configured, but the system loses flexibility for plug and play scenarios
Solution Approach 1:
The patent implements feedback by using the covariance matrix of the input audio signal to determine the auxiliary downmix matrix. The covariance matrix captures the statistical properties of the audio signal, and its eigenvectors are used to construct the downmix matrix, allowing the system to adapt to different playback configurations based on the actual signal characteristics rather than relying on pre-configured information.
3Adaptability or versatility
If the downmix matrix is determined adaptively using eigenvectors and subspace angles, then flexibility for arbitrary channel configurations is achieved, but the computational complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-computing the eigenvectors of the covariance matrix before the actual downmixing operation. The auxiliary downmix matrix is determined in advance based on the input signal's statistical properties, which then guides the subsequent downmixing process. This preliminary determination of the downmix matrix reduces the computational burden during real-time audio processing.
Data Source
AI summary
The invention relates to audio signal processing apparatuses and methods, such as an audio signal downmixing apparatus (105) for processing an input audio signal comprising a plurality of input channels (113) into an output audio signal comprising a plurality of primary output channels (123) and at least one auxiliary output channel (125) using a downmix matrix D, wherein the downmix matrix D comprises a primary downmix matrix DU providing the plurality of primary output channels (123) and an auxiliary downmix matrix DW providing the at least one auxiliary output channel (125). The audio signal downmixing apparatus (105) comprises an auxiliary downmix matrix determiner (107) configured to determine the auxiliary downmix matrix DW, and a processor (109) configured to process the input audio signal into the output audio signal using the downmix matrix D.