Hierarchical Multi-Channel Audio Coding with Compact Coherence Side Info
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Solution Overview
Problem
Existing multi-channel audio coding techniques face limitations in achieving high-quality spatial representation due to the coarse nature of parametric side information, particularly in hierarchical coding schemes, which results in increased data rates and reduced spatial quality when trying to preserve the spatial properties of multi-channel audio signals.
Innovation Solution
A hierarchical encoding and decoding approach that generates and uses compact parametric side information by deriving coherence information specifically for channel pairs with information from either the left or right side, allowing for a significant reduction in side information size while preserving the spatial properties of the audio signal, using a single ICC value to represent the left/right coherence and combining ICC values from separate channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If parametric side information is used to represent multi-channel audio signals, then data rate is reduced, but spatial quality deteriorates due to coarse representation
Solution Approach 1:
The patent segments the multi-channel audio signal into a downmix signal and separate channel signals. Parametric side information is generated only for the downmix signal, while the separate channel signals are transmitted without parametric coding. This segmentation allows the system to achieve data rate reduction through parametric coding of the downmix while maintaining spatial quality through the presence of the original channel signals.
2Device complexity
If hierarchical coding scheme is applied to multi-channel audio, then complexity is reduced, but spatial properties are lost due to coarse parametric information
Solution Approach 1:
The hierarchical coding scheme is segmented into multiple levels: a first level that generates parametric side information for a downmix signal, and a second level that processes separate channel signals. This segmentation allows the system to achieve complexity reduction through hierarchical processing while preserving spatial properties by maintaining the separate channel signals at each level.
3Productivity
If parametric side information size is reduced, then transmission efficiency is improved, but spatial coherence deteriorates
Solution Approach 1:
The patent segments the audio signal processing into a downmix component and separate channel components. Parametric side information is generated only for the downmix signal, which captures the spatial coherence of the overall multi-channel signal. The separate channel signals are transmitted without parametric coding, ensuring that transmission efficiency is improved through parametric representation while spatial coherence is maintained through the presence of the original channel signals.
Data Source
AI summary
A parametric representation of a multi-channel audio signal describes the spatial properties of the audio signal well with compact side information when a coherence information, describing the coherence between a first and a second channel, is derived within a hierarchical encoding process only for channel pairs including a first channel having only information of a left side with respect to a listening position and including a second channel having only information from a right side with respect to a listening position. As within the hierarchical process the multiple audio channels of the audio signal are downmixed iteratively into monophonic channels, one can pick the relevant parameters from an encoding step involving only channel pairs carrying the information needed to describe the spatial properties of the multi-channel audio signal.