Audio Signal Decoding With Temporal Alignment
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Solution Overview
Problem
In audio signal decoding, the challenge lies in reducing the difference between output signals generated at a second device and the original audio signals received at a first device, particularly in scenarios with limited communication bandwidth, where temporal shifts and phase mismatches between audio channels reduce the effectiveness of stereo coding techniques like Mid-Side (MS) and Parametric Stereo (PS) coding.
Innovation Solution
The solution involves a system that receives inter-channel prediction gain parameters and an encoded audio signal, and generates a synthesized side signal by dynamically adjusting the temporal mismatch and energy levels between audio channels, allowing for efficient bit allocation and prediction of side signals, thereby conserving bandwidth while maintaining audio quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional stereo coding techniques (MS/PS) are used, then audio signals can be transmitted, but the difference between output signals and original audio signals increases due to temporal shifts and phase mismatches
Solution Approach 1:
The patent applies preliminary action by performing temporal alignment and phase correction on the audio channels before encoding. The system estimates temporal shifts between mid and side channels and applies compensatory delays or advances to realign the channels prior to stereo coding, thereby preventing alignment errors from degrading audio quality
Solution Approach 2:
The patent implements feedback by continuously monitoring the temporal and phase alignment between audio channels and dynamically adjusting the alignment parameters. The system estimates alignment errors from the encoded audio signals and uses this information to correct future encoding operations, creating a closed-loop system that maintains accurate temporal and phase relationships
2Reliability
If more bits are allocated for encoding side signals, then audio quality improves, but communication bandwidth consumption increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the encoding parameters of side signals based on their actual information content. The system analyzes the temporal and phase characteristics of side signals and adapts the bit allocation accordingly, using fewer bits when side signals are highly predictable from mid signals and more bits when independent information is present, thereby optimizing the trade-off between audio quality and bandwidth efficiency
3Productivity
If temporal alignment is improved, then stereo coding effectiveness increases, but processing complexity increases
Solution Approach 1:
The patent applies self-service by implementing automated temporal shift estimation and correction algorithms that operate autonomously on the audio signals. The system automatically detects alignment errors between mid and side channels and applies corrective delays or advances without requiring manual intervention or complex external processing, thereby improving coding efficiency while keeping the processing complexity manageable through self-contained algorithms
Data Source
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AI summary
A device includes a receiver configured to receive an inter-channel prediction gain parameter and an encoded audio signal. The encoded audio signal includes an encoded mid signal. The device also includes a decoder configured to generate a synthesized mid signal based on the encoded mid signal. The decoder is configured to generate an intermediate synthesized side signal based on the synthesized mid signal and the inter-channel prediction gain parameter. The decoder is further configured to filter the intermediate synthesized side signal to generate a synthesized side signal.