Parametric Audio Channel Reconstruction via Coherence Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional multi-channel audio processing techniques suffer from inefficiencies in data transmission and artifact introduction, particularly in reconstructing surround sound formats, due to reliance on fully coherent channels and complex inter-channel coherence manipulation.
Innovation Solution
The approach involves determining different base channels for each output channel using varying degrees of uncorrelated transmitted channels, reducing coherence between channels to achieve de-correlated output signals, and using parametric side information to reconstruct original channels without requiring additional carrier channels, thus simplifying the decoding process and reducing computational workload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional joint stereo techniques are used to reduce data transmission, then data transmission efficiency is improved, but artifact introduction increases due to full coherence manipulation
Solution Approach 1:
The patent changes the coherence parameter from fully coherent (conventional joint stereo) to partially coherent by introducing a coherence coefficient α that ranges from 0 to 1. This allows the system to transmit less data (improving efficiency) while controlling the degree of coherence to minimize artifacts. The synthesized channel uses a linear combination of the transmitted channel and an orthogonal channel with weighting factor α, thereby adjusting the coherence level to balance data efficiency and artifact reduction.
2Manufacturing precision
If fully coherent channels are used for multi-channel reconstruction, then reconstruction accuracy is improved, but device complexity increases due to complex coherence manipulation
Solution Approach 1:
The patent simplifies the coherence manipulation by parameterizing it through a single coherence coefficient α. Instead of complex multi-parameter coherence control, the system uses one parameter to adjust the degree of coherence between channels. This reduces the computational complexity while maintaining reconstruction accuracy, as the synthesized channel is generated using a simple linear combination with the orthogonal channel.
Solution Approach 2:
The patent segments the multi-channel signal processing into independent channel pairs (e.g., L/R, Ls/Rs) and processes each pair separately using the same coherence-based synthesis method. This segmentation allows the system to maintain reconstruction accuracy for each channel pair while reducing overall system complexity through modular processing.
3Manufacturing precision
If additional carrier channels are transmitted for surround sound reconstruction, then reconstruction quality is improved, but data transmission load increases
Solution Approach 1:
The patent introduces an orthogonal channel as an intermediary component that does not require separate transmission. The orthogonal channel is generated locally at the receiver using simple signal processing (e.g., Hilbert transform or artificial intelligence-based generation). This intermediary allows the system to achieve high reconstruction quality by synthesizing missing channels from the transmitted channel and its orthogonal counterpart, thereby avoiding the need to transmit additional carrier channels and reducing data transmission load.
Data Source
AI summary
The apparatus for constructing a multi-channel output signal using an input signal and parametric side information, the input signal including the first input channel and the second input channel derived from an original multi-channel signal, and the parametric side information describing interrelations between channels of the multi-channel original signal uses base channels for synthesizing first and second output channels on one side of an assumed listener position, which are different from each other. The base channels are different from each other because of a coherence measure. Coherence between the base channels (for example the left and the left surround reconstructed channel) is reduced by calculating a base channel for one of those channels by a combination of the input channels, the combination being determined by the coherence measure. Thus, a high subjective quality of the reconstruction can be obtained because of an approximated original front/back coherence.