IPD Parameter Modification for Audio Channel Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In audio signal encoding, the temporal misalignment between multiple microphones due to varying distances from sound sources leads to phase differences that reduce the effectiveness of stereo encoding techniques, such as mid-side and parametric stereo coding, resulting in reduced coding gains and increased bit usage.
Innovation Solution
A system that adjusts inter-channel phase difference (IPD) parameters based on a mismatch value indicating temporal delay between reference and target audio channels, allowing for improved alignment and encoding efficiency by modifying IPD parameter values during the up-mixing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If stereo encoding is performed on misaligned audio signals from multiple microphones, then encoding complexity is reduced, but coding gain is reduced and phase differences become less relevant
Solution Approach 1:
The patent applies preliminary time-alignment to audio signals from multiple microphones before stereo encoding. By calculating and compensating for temporal delays caused by different microphone positions relative to the sound source, the signals are aligned in time prior to encoding. This preliminary alignment preserves phase relationships and enables effective stereo encoding while maintaining coding gain, resolving the contradiction between encoding simplicity and information preservation
2Adaptability or versatility
If audio signals from multiple microphones are used without alignment, then microphone array flexibility is increased, but phase differences between frequency-domain versions become less relevant
Solution Approach 1:
The patent dynamically adjusts the time-alignment parameter (temporal delay compensation) based on the specific microphone configuration and sound source position. By calculating the actual temporal delay for each microphone pair and applying appropriate compensation, the system maintains phase difference accuracy despite using flexible microphone arrays with varying positions and orientations
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method includes performing modifying, at a decoder, at least a portion of inter-channel phase difference (IPD) parameter values based on a mismatch value to generate modified IPD parameter values. The mismatch value is indicative of an amount of temporal misalignment between an encoder-side reference channel and an encoder-side target channel. The modified IPD parameter values are applied to a decoded frequency-domain mid channel during an up-mix operation.