Multichannel Audio Reconstruction with Parametric Upmix Coefficients
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Solution Overview
Problem
Existing audio coding systems face challenges in efficiently encoding and reconstructing multichannel audio signals due to bandwidth limitations and storage constraints, necessitating new methods to reduce bandwidth requirements and memory size while maintaining audio fidelity.
Innovation Solution
The proposed method involves reconstructing an N-channel audio signal from a single-channel downmix signal using dry and wet upmix parameters, where the number of wet upmix coefficients exceeds the received parameters by employing a predefined matrix class to populate an intermediate matrix, thereby reducing the amount of metadata required for reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multichannel audio signals are transmitted or stored, then audio fidelity is maintained, but bandwidth requirements and memory size increase
Solution Approach 1:
The patent segments the multichannel audio signal into a downmix signal containing only a subset of channels and separate side information parameters. This segmentation allows transmission of audio content using fewer channels (e.g., stereo instead of surround sound), thereby reducing bandwidth and storage requirements while maintaining acceptable audio fidelity through parametric reconstruction of the full multichannel signal at the decoder.
2Quantity of substance
If audio coding systems use parametric coding to reduce bandwidth, then bandwidth requirements decrease, but the complexity of signal reconstruction increases
Solution Approach 1:
The patent introduces an intermediary approach by using a downmix signal as a foundation and adding parametric side information (level differences, cross-correlation parameters) to reconstruct the original multichannel signal. This intermediary method balances bandwidth efficiency with reconstruction complexity by leveraging the relationship between the downmix and the full-channel signal, allowing the decoder to generate missing channels through controlled parametric processing rather than requiring full-channel transmission.
3Reliability
If more channels are transmitted to maintain audio quality, then audio fidelity improves, but storage size increases
Solution Approach 1:
The patent applies partial action by transmitting only a subset of audio channels in the downmix signal rather than all channels, combined with parametric side information that enables reconstruction of the remaining channels. This partial transmission approach reduces storage size requirements while maintaining sufficient audio quality for the application, accepting that not all original channel information is transmitted verbatim but can be synthesized through the parametric model.
Data Source
AI summary
An encoding system encodes an N-channel audio signal (X), wherein N≥3, as a single-channel downmix signal (Y) together with dry and wet upmix parameters ({tilde over (C)}, {tilde over (P)}). In a decoding system, a decorrelating section outputs, based on the downmix signal, an (N−1)-channel decorrelated signal (Z); a dry upmix section maps the downmix signal linearly in accordance with dry upmix coefficients (C) determined based on the dry upmix parameters; a wet upmix section populates an intermediate matrix based on the wet upmix parameters and knowing that the intermediate matrix belongs to a predefined matrix class, obtains wet upmix coefficients (P) by multiplying the intermediate matrix by a predefined matrix, and maps the decorrelated signal linearly in accordance with the wet upmix coefficients; and a combining section combines outputs from the upmix sections to obtain a reconstructed signal ({circumflex over (X)}) corresponding to the signal to be reconstructed.