Downmix Level Parameter for Error-Robust Multichannel Reconstruction
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Solution Overview
Problem
Existing multi-channel audio reconstruction methods, such as BCC coding, require each inter-channel level difference for perfect reconstruction, making them error-prone and susceptible to artefacts due to level variations and phase dependencies, especially in error-prone transmission channels.
Innovation Solution
A parameterization concept that includes an additional level parameter calculated to ensure the energy of the downmix channel weighted by this parameter equals the sum of energies of the original channels, allowing for improved multi-channel reconstruction with reduced level variations and artefacts, and flexibility in adapting to different down-mix signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If binaural cue coding is used for multi-channel reconstruction, then the reconstruction can be achieved with a down-mix channel and side information, but the method is error-prone and susceptible to artifacts due to level variations and phase dependencies
Solution Approach 1:
The patent introduces a level parameter that explicitly accounts for energy relationships between down-mix channels and original channels. By changing the parameter representation to include this energy-based level information, the system achieves more reliable reconstruction that is less sensitive to transmission errors and phase dependencies, while maintaining the adaptability of multi-channel reconstruction from down-mix signals
2Measurement precision
If all inter-channel level differences are transmitted for perfect reconstruction, then reconstruction accuracy is improved, but bit rate overhead increases
Solution Approach 1:
The patent extracts only the essential level parameter that captures the energy relationship between down-mix and original channels, rather than transmitting all inter-channel level differences. This selective extraction maintains sufficient reconstruction accuracy while significantly reducing the bit rate overhead required for parameter transmission
3Device complexity
If the same parameter set is used for all channel configurations, then system complexity is reduced and scalability is improved, but flexibility in optimizing for specific signal characteristics is lost
Solution Approach 1:
The patent designs a universal parameter set that includes the level parameter, which can be applied across different channel configurations (5.1, 7.1, etc.) and signal types. This single parameter structure serves multiple functions: it works for various channel layouts, adapts to different signal characteristics, and maintains consistent reconstruction quality, thereby achieving both simplicity and flexibility
Data Source
AI summary
A parameter representation of a multi-channel signal having several original channels includes a parameter set, which, when used together with at least one down-mix channel allows a multi-channel reconstruction. An additional level parameter is calculated such that an energy of the at least one downmix channel weighted by the level parameter is equal to a sum of energies of the original channels. The additional level parameter is transmitted to a multi-channel reconstructor together with the parameter set or together with a down-mix channel. An apparatus for generating a multi-channel representation uses the level parameter to correct the energy of the at least one transmitted down-mix channel before entering the down-mix signal into an up-mixer or within the up-mixing process.