Multi-Channel Signal Phase Shifting for Audio Encoding
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Solution Overview
Problem
Existing multi-channel signal encoding technologies face challenges in efficiently encoding and decoding stereo signals, particularly in managing phase differences and energy distribution between channels, leading to issues like gain divergence and quality loss during downmixing and upmixing processes.
Innovation Solution
The proposed solution involves an encoding apparatus that extracts parameters indicating characteristic relationships between channels, shifts the phase of multi-channel signals to minimize phase differences, and generates a bitstream by encoding downmix and residual signals, along with these parameters, to maintain signal quality and prevent gain divergence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase shifting is applied to minimize phase differences between channels, then signal integrity is improved, but computational complexity increases
Solution Approach 1:
The patent applies preliminary phase shifting to the input multi-channel signals before downmixing operations. By pre-adjusting the phase of each channel signal based on extracted phase difference parameters, the system ensures that signals are properly aligned before processing, preventing gain divergence and maintaining signal integrity throughout the encoding pipeline without requiring complex real-time adjustments later
Solution Approach 2:
The patent replaces complex mechanical or iterative phase alignment mechanisms with a computational approach using extracted phase parameters. Instead of using elaborate feedback loops or iterative optimization systems to maintain phase coherence, the invention uses direct parameter extraction and application through phase shifting operations, simplifying the overall system architecture while maintaining reliability
2Productivity
If downmixing is performed to reduce channel count, then data compression is improved, but energy distribution and phase coherence are degraded
Solution Approach 1:
The patent performs preliminary phase shifting of input channel signals before the downmixing operation. By pre-aligning the phases of individual channels based on extracted phase difference parameters, the system ensures that the downmixing process operates on phase-coherent signals, thereby maintaining phase coherence in the downmixed output while still achieving effective data compression
Solution Approach 2:
The patent extracts phase difference parameters from the input multi-channel signals and uses this feedback information to adjust the phase of individual channels before downmixing. This feedback loop ensures that the downmixing operation preserves phase coherence by compensating for initial phase differences, thus maintaining reliability during the compression process
3Reliability
If phase difference parameters are extracted and applied, then gain divergence is prevented, but encoding complexity increases
Solution Approach 1:
The patent extracts only the essential phase difference parameters from the input multi-channel signals, separating this critical information from the full signal data. By extracting and encoding only the phase parameters rather than processing entire waveforms, the system prevents gain divergence while minimizing the increase in encoding complexity through selective parameter extraction
Solution Approach 2:
The patent transforms the complex problem of maintaining gain stability by changing from direct signal processing to parameter-based processing. Instead of manipulating full audio waveforms to maintain gain stability, the invention extracts phase parameters, applies phase shifting based on these parameters, and thereby prevents gain divergence through parameter manipulation rather than complex signal processing
Data Source
AI summary
Disclosed is an apparatus for encoding and decoding multi-channel signals. The apparatus for encoding the multi-channel signals may shift a phase of the multi-channel signals based on a characteristic of the multi-channel signals. An encoded bitstream with respect to the multi-channel signals may be generated using a downmix signal and a residual signal extracted from the phase-shifted multi-channel signals.