Time-Domain Inter-Channel Prediction for Audio Encoding
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Solution Overview
Problem
Existing audio encoding technologies face inefficiencies in handling temporal shifts and phase mismatches between multiple microphones, leading to reduced coding gains and suboptimal stereo coding performance in scenarios with temporal shifts between audio channels.
Innovation Solution
The proposed solution involves a system that uses time-domain inter-channel prediction and down-mixing techniques to generate mid and side channels, with dynamic adjustment of temporal mismatch values and relative gain parameters to align and normalize audio signals from multiple microphones, enabling efficient encoding and decoding of audio signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If traditional stereo encoding is used without temporal alignment, then encoding simplicity is maintained, but coding gains are reduced due to temporal shifts and phase mismatches between channels
Solution Approach 1:
The patent applies preliminary action by performing temporal alignment and phase matching of audio channels before the encoding process. The system estimates temporal shifts between channels and applies compensation in advance, ensuring that the audio signals are properly synchronized before stereo encoding begins. This preliminary synchronization prevents loss of coding gains that would otherwise occur due to temporal misalignment.
Solution Approach 2:
The system implements self-service by automatically detecting and correcting temporal shifts and phase mismatches without requiring manual intervention. The encoder autonomously estimates the temporal alignment between channels, calculates appropriate compensation parameters, and applies corrections to the audio signals. This self-correcting mechanism maintains high coding gains while avoiding the complexity of manual alignment procedures.
2Reliability
If temporal alignment processing is applied to correct phase mismatches, then stereo coding performance is improved, but processing complexity and computational load increase
Solution Approach 1:
The patent replaces complex mechanical or manual alignment procedures with automated signal processing algorithms. Instead of using traditional methods that require extensive computational resources for frame-by-frame analysis and manual adjustment, the system employs efficient algorithms that estimate temporal shifts and apply corrections through systematic mathematical operations. This substitution maintains high stereo coding performance while reducing processing complexity.
Solution Approach 2:
The system applies parameter changes by modifying temporal and phase parameters of the audio signals to achieve proper alignment. Rather than fundamentally changing the encoding architecture or introducing complex processing stages, the patent adjusts specific parameters such as temporal shift values and phase compensation factors. These targeted parameter adjustments improve stereo coding performance without substantially increasing overall processing complexity.
3Loss of energy
If multiple audio channels are encoded independently, then channel independence is maintained, but data transmission requirements increase
Solution Approach 1:
The patent applies merging by combining the encoding of multiple audio channels into a unified stereo encoding process. After performing temporal alignment and phase matching, the system encodes the aligned channels together using stereo encoding techniques that exploit inter-channel correlations. This merging reduces the total data transmission requirements compared to encoding each channel independently, while still maintaining the essential independence and distinct characteristics of each audio channel through proper stereo encoding.
Data Source
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AI summary
A method includes decoding a low-band portion of an encoded mid channel to generate a decoded low-band mid channel. The method also includes filtering the decoded low-band mid channel according to one or more filter coefficients to generate a low-band filtered mid channel. The method also includes generating an inter-channel predicted signal based on the low-band filtered mid channel and the inter-channel prediction gain. The method further includes generating a low-band left channel and a low-band right channel based on an up-mix factor, the decoded low-band mid channel, and the inter-channel predicted signal.