Multi-Channel Audio Encoder ITD Stability Control
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Solution Overview
Problem
Existing PS encoding schemes for stereo signals suffer from unstable ITD values due to environmental factors like background noise, reverberation, and multi-party speech, leading to poor quality and inter-frame discontinuity of the downmixed signal.
Innovation Solution
A method for encoding multi-channel signals that involves determining an initial ITD value, controlling the quantity of target frames allowed to appear continuously based on signal characteristics, and reusing the ITD value of a previous frame when conditions are met, to stabilize the ITD value and improve encoding quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing PS encoding schemes calculate ITD based on cross correlation coefficients in noisy environments, then encoding compression is achieved, but ITD stability deteriorates due to background noise, reverberation, and multi-party speech
Solution Approach 1:
The patent changes the parameter basis for ITD calculation from cross correlation coefficients to peak amplitude ratios of cross correlation coefficients. This parameter transformation makes the ITD calculation more robust to environmental noise, reverberation, and multi-party speech, thereby improving ITD stability while maintaining encoding compression
Solution Approach 2:
The patent introduces a feedback mechanism where the stability of ITD values is continuously monitored and used to adaptively adjust the encoding process. When ITD instability is detected due to environmental factors, the system adjusts the number of target frames and ITD reuse strategies to maintain stability
2Adaptability or versatility
If ITD value transitions frequently to adapt to changing acoustic environments, then encoding adaptability improves, but inter-frame discontinuity increases causing acoustic image jitter and auditory freezing
Solution Approach 1:
The patent implements a dynamic ITD management system that adaptively controls ITD value transitions based on acoustic environment conditions. The system dynamically adjusts the number of target frames and ITD reuse duration according to signal characteristics, achieving both adaptability to environmental changes and continuity of the acoustic image
Solution Approach 2:
The patent applies prior cushioning by pre-establishing ITD value reuse mechanisms and target frame controls before instability occurs. When environmental factors threaten ITD stability, the system has pre-configured strategies to maintain continuous ITD values, preventing acoustic image jitter and auditory freezing
3Stability of the object's composition
If ITD value is reused across multiple frames to maintain stability, then signal continuity improves, but phase information retention may deteriorate
Solution Approach 1:
The patent applies partial action by selectively reusing ITD values only when stability is needed rather than always. The system controls the number of target frames to balance ITD stability with phase information retention, reusing ITD values partially across frames based on acoustic conditions rather than universally
Data Source
AI summary
A method for encoding an audio signal includes obtaining an ITD value of a current frame of an audio signal; obtaining a characteristic parameter of the current frame, wherein the characteristic parameter comprises at least one of a signal-to-noise ratio of the current frame or a peak feature of cross correlation coefficients of the current frame; determining, based on the characteristic parameter, whether to use the initial ITD value as the finalized ITD value of the current frame; and encoding the current frame based on the finalized ITD value of the current frame, wherein if the initial ITD value is determined as not used as the finalized ITD value of the current frame, the finalized ITD value of the current frame is the same as a finalized ITD value of a previous frame of the current frame.