Adaptive Residual Audio Coding Spatial Parameter Limiter
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Solution Overview
Problem
Existing audio coding techniques face challenges in achieving high-quality compression while minimizing artifacts, especially when dealing with stereo signals, as they often result in energy instability and inefficient bandwidth usage due to the limitations of static coding methods.
Innovation Solution
The proposed solution involves an audio encoder and decoder that utilize a parameter extractor to derive spatial parameters, a limiter to constrain these parameters, and a down-mixer to split the audio signal into a downmix signal and a residual signal, ensuring minimal energy in the residual channel through dynamic adaptation based on the limited spatial parameters. This process is reversible, maintaining energy conservation and reducing bandwidth requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If static coding methods are used for audio compression, then device complexity is reduced, but audio quality deteriorates and energy instability occurs
Solution Approach 1:
The patent applies dynamics by transitioning from static coding methods to dynamic adaptive coding. The system continuously adjusts coding parameters based on real-time analysis of the audio signal characteristics, allowing the encoder to adapt to changing signal conditions. This dynamic adaptation resolves the contradiction by maintaining audio quality stability without requiring overly complex fixed algorithms.
Solution Approach 2:
The patent implements parameter changes by modifying coding parameters adaptively based on signal characteristics. The system analyzes temporal and spectral features of the audio signal and adjusts compression parameters accordingly, enabling high-quality compression while managing complexity through intelligent parameter adaptation rather than fixed complex structures.
2Quantity of substance
If compression ratio is increased to reduce bandwidth, then bandwidth usage is reduced, but audio quality deteriorates due to energy instability
Solution Approach 1:
The system uses dynamic adaptation to adjust compression intensity based on signal characteristics. By continuously monitoring temporal and spectral features, the encoder can apply higher compression where signal redundancy exists and maintain lower compression where quality is critical, achieving bandwidth reduction without compromising overall audio quality stability.
Solution Approach 2:
The patent applies local quality by differentiating compression strategies across different temporal and spectral regions of the audio signal. The system identifies regions with different importance and applies appropriate compression levels locally, allowing aggressive compression in less critical areas while preserving quality in important regions, thus reducing total bandwidth while maintaining audio quality.
3Productivity
If residual signal energy is minimized through adaptive coding, then coding efficiency is improved, but device complexity increases due to dynamic parameter adjustment
Solution Approach 1:
The patent applies segmentation by dividing the audio signal into temporal and spectral segments for independent analysis. The encoder processes different frequency bands and time frames separately, applying adaptive coding parameters to each segment. This segmentation approach improves coding efficiency by targeting residual energy reduction in specific regions while managing complexity through modular, localized processing rather than global complex algorithms.
Data Source
AI summary
An audio signal having at least two channels can be efficiently down-mixed into a downmixe signal and a residual signal, when the down-mixing rule used depends on a spatial parameter that is derived from the audio signal and that is post-processed by a limiter to apply a certain limit to the derived spatial parameter with the aim of avoiding instabilities during the up-mixing or down-mixing process. By having a down-mixing rule that dynamically depends on parameters describing an interrelation between the audio channels, one can assure that the energy within the down-mixed residual signal is as minimal as possible, which is advantageous in the view of coding efficiency. By post processing the spatial parameter with a limiter prior to using it in the down-mixing, one can avoid instabilities in the down- or up-mixing, which otherwise could result in a disturbance of the spatial perception of the encoded or decoded audio signal.