Audio Encoder Context Mapping for Resolution Switching Efficiency
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Solution Overview
Problem
Conventional audio coding techniques experience a significant loss in coding efficiency when frequently switching between different time/frequency resolutions, as they often 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 down-sampling and up-sampling of previous context information, allowing for more frequent switching between block lengths without compromising coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If context is reset when switching between different time/frequency resolutions, then device complexity is reduced and ease of operation is improved, but coding efficiency deteriorates significantly
Solution Approach 1:
The patent applies preliminary action by pre-processing context information through down-sampling and up-sampling operations before switching between resolutions. The context is prepared in advance by mapping coefficients from one resolution to another, so that when switching occurs, the decoder already has appropriate context information ready, avoiding the need to reset and rebuild context from scratch.
Solution Approach 2:
The patent changes parameters by transforming the resolution parameter of context coefficients through down-sampling (reducing resolution) and up-sampling (increasing resolution) operations. This allows the context to adapt to different block lengths and resolutions dynamically, maintaining coding efficiency across frequent switches by adjusting the context resolution to match the current signal characteristics.
2Adaptability or versatility
If switching between different block lengths occurs frequently, then adaptability to signal characteristics is improved, but coding efficiency deteriorates due to context loss
Solution Approach 1:
The patent prepares context information in advance by down-sampling previous context coefficients to match the resolution of upcoming blocks with different lengths. This preliminary preparation ensures that when frequent switching occurs, the context is already adapted to the new resolution, maintaining coding efficiency while enabling frequent adaptation to different signal characteristics.
Solution Approach 2:
The patent makes the context mechanism universal by implementing up-sampling and down-sampling capabilities that allow the same context structure to serve multiple resolution requirements. The context can be transformed to match any block length or resolution, making it versatile for handling frequent switches between different signal types and resolutions without losing efficiency.
3Productivity
If context mapping with down-sampling and up-sampling is implemented, then coding efficiency is maintained during frequent switching, but device complexity increases
Solution Approach 1:
The patent manages device complexity by implementing parameter changes through systematic down-sampling and up-sampling operations. These operations transform context coefficients between different resolutions using defined mathematical relationships, allowing the system to maintain coding efficiency during frequent switching while keeping the complexity manageable through structured parameter transformation rather than complex adaptive algorithms.
Data Source
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AI summary
An audio encoder (100) for encoding segments of coefficients, the segments of coefficients representing different time or frequency resolutions of a sampled audio signal, the audio encoder (100) comprising a processor (110) 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 (100) further comprises an entropy encoder (120) for entropy encoding the current coefficient based on the coding context to obtain an encoded audio stream.