Multi-Channel Downmix Level Parameter for Error-Robust Reconstruction
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Solution Overview
Problem
Existing multi-channel audio coding techniques face challenges in efficiently reconstructing audio signals with errors in inter-channel level differences, leading to level variations and artefacts, especially in error-prone transmission channels, and require each inter-channel level difference for perfect reconstruction, which is impractical and error-sensitive.
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 downmix signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If each inter-channel level difference is used for multi-channel reconstruction, then reconstruction accuracy is improved, but error sensitivity increases and reliability deteriorates in error-prone transmission channels
Solution Approach 1:
The patent extracts only the essential energy information from the original multi-channel signal by computing a single level parameter based on the downmix channel energy and original channel energies. This extracted parameter set is sufficient for reconstruction purposes and eliminates the need to transmit all inter-channel level differences, thereby reducing error sensitivity while maintaining reconstruction accuracy.
Solution Approach 2:
The patent transforms the traditional approach of using multiple inter-channel level difference parameters into a single level parameter representation. By changing the parameterization from multiple relative level differences to one absolute energy-based parameter, the system achieves both compression and improved error robustness while maintaining reconstruction fidelity.
2Measurement precision
If a complete parameter set including all inter-channel level differences is transmitted, then reconstruction precision is improved, but bit rate increases
Solution Approach 1:
The patent extracts only the necessary energy information from the original multi-channel signal by computing a single level parameter based on the downmix channel energy and original channel energies. This extracted parameter is sufficient for reconstruction purposes and eliminates the need to transmit all inter-channel level differences, thereby reducing bit rate overhead significantly.
Solution Approach 2:
The patent merges multiple inter-channel level difference parameters into a single level parameter by combining energy information from the downmix channel and original channels. This consolidation reduces the number of parameters that need to be transmitted while preserving the essential spatial information needed for multi-channel reconstruction.
3Stability of the object's composition
If traditional multi-channel reconstruction methods are used, then channel correlation is maintained, but level variations and artefacts occur in error-prone channels
Solution Approach 1:
The patent prepares for potential transmission errors by using a robust energy-based level parameter that is less sensitive to errors. By pre-computing this parameter from energy information rather than precise inter-channel level differences, the system cushions against the harmful effects of transmission errors, preventing level variations and artefacts in the reconstructed signal.
4Device complexity
If fixed parameter sets are used for all channel configurations, then system complexity is reduced, but adaptability to different configurations deteriorates
Solution Approach 1:
The patent creates a universal level parameter definition that works across different multi-channel configurations (5.1, 7.1, stereo, etc.). The single level parameter based on downmix channel energy and original channel energies serves multiple functions and adapts to various channel configurations without requiring configuration-specific parameter sets, thereby maintaining low system complexity while achieving high adaptability.
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 downmix channel before entering the down-mix signal into an upmixer or within the up-mixing process.