N-N/2-N Audio Upmixing for Multi-Channel Quality
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Solution Overview
Problem
MPEG Surround (MPS) technology faces challenges in processing multi-channel audio signals with more than 5.1 or 7.1 channels, leading to degradation in audio signal quality due to constraints in backward compatibility and bitstream compression.
Innovation Solution
The N-N/2-N structure method, which involves identifying residual signals and N/2 channel downmix signals, applying them to matrices with decorrelators, and generating N channel output signals through a series of matrix operations, including the use of Channel Level Difference (CLD) and Inter channel Correlation/Coherence (ICC) parameters, to effectively process and upmix multi-channel audio signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If MPEG Surround structure is used for multi-channel audio processing, then backward compatibility is maintained, but audio signal quality degrades when processing more than 5.1 or 7.1 channels
Solution Approach 1:
The patent segments the multi-channel audio processing into multiple independent processing paths. Instead of processing all N channels through a single MPS structure, the system divides channels into groups (e.g., first group of 5.1 channels, second group of additional channels) and processes each group separately with dedicated downmixing and upmixing operations, thereby maintaining quality for each segment while achieving overall N-channel support
Solution Approach 2:
The patent implements a nested processing structure where multiple levels of downmixing and upmixing are applied hierarchically. The N-channel signal is first downmixed to an intermediate format, then further downmixed to stereo/mono for backward compatibility. During decoding, the process is reversed with nested upmixing operations that reconstruct the full N-channel signal while preserving the quality of embedded 5.1 or 7.1 channel content
2Quantity of substance
If N channel input signals are processed through traditional MPS, then bitstream compression is achieved, but the number of supportable channels is limited to 5.1 or 7.1
Solution Approach 1:
The patent implements dynamic channel handling where the system can adaptively process different channel configurations (N channels where N > 7.1) through a unified framework. The processing structure dynamically adjusts the number of downmixing stages and upmixing operations based on the input channel count, enabling flexible support for various channel layouts beyond the fixed 5.1 or 7.1 limitations of traditional MPS
Solution Approach 2:
The patent extends the traditional MPS framework by adding dimensional flexibility to the channel processing. Instead of being constrained to fixed channel groups, the system introduces an additional dimension of channel organization where N channels can be arbitrarily divided into multiple groups, each processed through standardized downmix/upmix operations, thereby enabling support for any number of channels while maintaining the bitstream compression efficiency of MPS
Data Source
AI summary
Disclosed are a multi-channel audio signal processing method and a multi-channel audio signal processing apparatus. The multi-channel audio signal processing method may generate N channel output signals from N/2 channel downmix signals based on an N-N/2-N structure.