Audio Entropy Coding Across Spectral Resolution Switching
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Solution Overview
Problem
Conventional audio coding methods experience a significant loss in coding efficiency when frequent switching occurs between different time or frequency resolutions, as they reset the context, leading to sub-optimal codebook selection and reduced adaptation to signal characteristics.
Innovation Solution
Implementing a context mapping mechanism that derives new contexts for coefficients with changing resolutions by using interpolation, extrapolation, sub-sampling, or up-sampling of previous context information, allowing for more frequent switching between time or frequency resolutions without compromising coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If context is reset when switching between different time or frequency resolutions, then device complexity is reduced, but coding efficiency deteriorates significantly
Solution Approach 1:
The patent applies preliminary action by pre-establishing multiple codebooks corresponding to different time and frequency resolutions before switching occurs. When a resolution switch is detected, the system activates the pre-prepared codebook matching the new resolution, avoiding the need to reset and rebuild context from scratch. This allows frequent switching between resolutions while maintaining coding efficiency, as the appropriate codebook is already available.
2Adaptability or versatility
If frequent switching between different time or frequency resolutions occurs, then adaptability to signal characteristics is improved, but coding efficiency deteriorates due to context reset
Solution Approach 1:
The patent implements dynamics by making the codebook selection adaptive and dynamic based on the current signal characteristics and resolution requirements. The system continuously monitors signal properties and automatically switches between different codebooks (with different time/frequency resolutions) to match the signal, enabling frequent adaptation without context reset penalties. This dynamic codebook selection mechanism resolves the contradiction between adaptability and coding efficiency.
3Productivity
If context is maintained across resolution switches, then coding efficiency is improved, but device complexity increases due to context mapping requirements
Solution Approach 1:
The patent applies segmentation by dividing the context management into separate, independent codebooks for different time and frequency resolutions. Instead of maintaining a single complex context that requires mapping and transformation across resolutions, the system segments the codebooks so that each resolution has its own dedicated codebook. This eliminates the need for complex context mapping operations while preserving coding efficiency, as each codebook is optimized for its specific resolution.
Data Source
AI summary
An audio encoder for encoding segments of coefficients, the segments of coefficients representing different time or frequency resolutions of a sampled audio signal, the audio encoder including a processor for deriving a coding context for a currently encoded coefficient of a current segment based on a previously encoded coefficient of a previous segment, the previously encoded coefficient representing a different time or frequency resolution than the currently encoded coefficient. The audio encoder further includes an entropy encoder for entropy encoding the current coefficient based on the coding context to obtain an encoded audio stream.