Audio Entropy Context Mapping Across Resolution Switches
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Solution Overview
Problem
Conventional audio coding techniques suffer from sub-optimal coding efficiency when frequent switching between different time/frequency resolutions occurs, leading to a significant loss in coding efficiency due to the need for resetting the context and using fall-back codebooks.
Innovation Solution
The implementation of a context mapping mechanism that derives new contexts for coefficients with changing resolutions from previous coefficients, using methods such as interpolation, extrapolation, sub-sampling, and up-sampling to adapt the codebook determination, allowing for more frequent switching without compromising coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If context resetting is used when switching between different time/frequency resolutions, then implementation simplicity is maintained, but coding efficiency deteriorates significantly
Solution Approach 1:
The patent applies preliminary action by pre-adapting the context to the new resolution before actual coding operations begin. When a resolution switch is detected, the context is proactively adjusted using interpolation or extrapolation methods based on previously available context data, ensuring that the context is already optimized for the new resolution when coding resumes, thereby avoiding efficiency losses.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting context parameters (such as codebook selection and probability distributions) according to the current resolution. Instead of resetting these parameters, the system continuously adapts them by interpolating or extrapolating from previous resolution parameters, allowing smooth transitions between different time/frequency resolutions while maintaining coding efficiency.
2Adaptability or versatility
If frequent switching between different resolutions is allowed, then adaptability to signal characteristics is improved, but coding efficiency deteriorates due to context resetting
Solution Approach 1:
Before each resolution switch, the system performs preliminary context adaptation using interpolation or extrapolation methods. This allows frequent switching between resolutions (improving adaptability) while maintaining coding efficiency because the context is already prepared for the new resolution state, eliminating the need for fall-back codebooks and full resets.
Solution Approach 2:
The patent introduces dynamics by making the context continuously adaptable to changing resolutions. Instead of static context resetting, the system dynamically adjusts context parameters in real-time based on the current resolution and signal characteristics, enabling frequent switching without efficiency penalties. The context evolves smoothly through interpolation/extrapolation as resolutions change.
3Reliability
If context is built from scratch after resetting, then synchronization between encoder and decoder is ensured, but coding efficiency is reduced due to lack of contextual information
Solution Approach 1:
The patent applies parameter changes by continuously updating context parameters based on the current resolution and previously decoded information. Instead of resetting parameters to default values, the system transforms and adapts previous context parameters to the new resolution using interpolation or extrapolation, maintaining both synchronization and coding efficiency.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining the context across resolution switches rather than resetting it. The context information from previous resolutions is continuously utilized and adapted through interpolation or extrapolation methods, ensuring that no valuable contextual information is lost during transitions between different time/frequency resolutions.
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.