Adaptive Stereo Coding With L/R, M/S, and PS Mode Switching
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Solution Overview
Problem
Existing stereo audio coding methods, such as MPEG AAC and MPEG Surround, face inefficiencies when dealing with independent left and right channels, as they either fall back to plain L/R encoding or use PS encoding with residual, which can lead to suboptimal coding performance in certain situations.
Innovation Solution
An audio encoder and decoder system that combines adaptive L/R or M/S perceptual stereo coding with PS coding using a residual, allowing seamless switching between L/R and PS coding with residual in a frequency- and time-variant manner, using a transform stage to convert downmix and residual signals into pseudo stereo signals for efficient encoding and decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PS encoding with residual is used for independent left and right channels, then coding efficiency is improved in some cases, but suboptimal coding performance occurs in certain situations
Solution Approach 1:
The encoder dynamically switches between PS encoding with residual and L/R encoding based on signal characteristics. A decision mechanism evaluates the stereo signal and selects the most appropriate encoding mode for each frame, allowing the system to adapt to different audio content and avoid suboptimal coding performance in situations where PS encoding is not suitable.
Solution Approach 2:
The system changes encoding parameters by switching between different stereo coding modes (PS with residual, PS without residual, L/R encoding). This parameter change allows the encoder to optimize coding efficiency for independent channels while maintaining reliability across various audio conditions by selecting the appropriate mode based on signal analysis.
2Productivity
If adaptive switching between L/R and PS coding is implemented, then coding efficiency is enhanced, but system complexity increases
Solution Approach 1:
The encoding process is segmented into distinct modes (PS with residual, PS without residual, L/R encoding), each handled by dedicated processing paths. This segmentation allows the complex adaptive switching functionality to be implemented through modular components, making the system more manageable and easier to implement despite the increased functionality.
Solution Approach 2:
The encoder includes an automated decision mechanism that independently evaluates the stereo signal characteristics and selects the appropriate encoding mode without requiring external control. This self-service approach handles the complexity of adaptive switching internally, reducing the burden on external control systems while maintaining enhanced coding efficiency.
Data Source
AI summary
Methods and systems for advanced stereo processing of an audio signal are disclosed. The methods and systems include selecting a coding mode of either transform coding or linear predictive coding and performing advanced stereo processing when in the selected coding mode. Both encoding and decoding operations are provided.