Audio Entropy Context Mapping for 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 resort to sub-optimal codebook selection due to context resetting, which is inadequate for efficient adaptation to signal characteristics at lower data rates.
Innovation Solution
Implementing a context mapping mechanism that derives new coding contexts for coefficients with changing resolutions by using interpolation, extrapolation, sub-sampling, or up-sampling techniques, 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 resetting is used 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/frequency resolutions before switching occurs. When a resolution switch is detected, the system activates the appropriate pre-prepared codebook immediately, avoiding the need to reset and rebuild context from scratch. This allows frequent switching between resolutions while maintaining coding efficiency, as the optimal codebook for each resolution is already prepared and 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 sub-optimal codebook selection
Solution Approach 1:
The patent implements dynamics by creating a dynamic codebook selection mechanism that automatically adapts to the current time/frequency resolution. The system maintains multiple codebooks in memory, each optimized for a specific resolution, and dynamically selects the appropriate codebook based on the current operating conditions. This enables frequent resolution switching while maintaining optimal coding efficiency for each resolution, as the codebook selection is dynamically adjusted rather than statically reset.
Solution Approach 2:
The patent applies parameter changes by varying the codebook parameters (specifically which codebook is active) based on the detected time/frequency resolution. When the resolution parameter changes, the system changes the corresponding codebook parameter to match, ensuring optimal coding performance. This parameter-based adaptation allows the system to efficiently handle frequent switching between different resolutions without losing coding efficiency.
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.