Secondary Transform Index Decoding Using Primary Transform Context
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Solution Overview
Problem
Existing video coding technologies face inefficiencies in representing intra prediction directions, particularly in entropy coding, leading to suboptimal compression ratios due to the varying likelihood of direction occurrence, which affects the bit usage and overall compression efficiency.
Innovation Solution
The proposed solution involves determining a context for entropy decoding a secondary transform index based on intra prediction mode information, block size, and primary transform type, allowing for more efficient entropy decoding of secondary transforms within video coding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform entropy coding is used for all intra prediction directions, then the coding process is simple, but compression efficiency is reduced due to not accounting for varying direction likelihood
Solution Approach 1:
The patent applies different entropy coding contexts based on the specific intra prediction direction being coded. Instead of using a uniform coding approach for all directions, the system selects different probability models and coding parameters tailored to each direction's statistical characteristics, thereby improving compression efficiency while maintaining reasonable coding complexity
Solution Approach 2:
The patent dynamically adapts the entropy coding parameters based on the intra prediction direction index. The coding process adjusts probability models and context variables according to the specific direction being encoded, allowing the system to respond to varying direction likelihoods rather than using static uniform coding parameters
2Measurement precision
If more bits are allocated to represent less likely intra prediction directions, then directional accuracy is improved, but overall bit usage increases reducing compression ratio
Solution Approach 1:
The patent changes the entropy coding parameters (probability models, context variables, and coding schemes) based on the intra prediction direction index. For less likely directions, the system uses probability models adapted to their specific statistical characteristics rather than forcing them into uniform coding schemes, achieving efficient representation without excessive bit allocation
Solution Approach 2:
The patent applies differential coding effort across different directions - using more sophisticated probability models only where necessary for less likely directions, while simpler models suffice for more common directions. This partial application of enhanced coding techniques optimizes the balance between directional accuracy and overall bit usage
3Measurement precision
If context-specific entropy decoding is implemented for secondary transform index, then decoding accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent segments the entropy decoding process into multiple contexts based on the primary transform type and intra prediction mode. Each segment uses decoding parameters optimized for its specific characteristics, improving overall decoding accuracy while distributing computational complexity across manageable segments rather than requiring a single complex unified model
Data Source
AI summary
Aspects of the disclosure provide a method and an apparatus including processing circuitry for video decoding. The processing circuitry decodes coded information for a transform block (TB) from a coded video bitstream. The coded information indicates one of intra prediction mode information that indicates an intra prediction mode used for the TB, a size of the TB, and a primary transform type used for the TB. The processing circuitry determines a context for entropy decoding a secondary transform index based on the one of the intra prediction mode information for the TB, the size of the TB, and the primary transform type used for the TB. The secondary transform index indicates a secondary transform in a set of secondary transforms that is to be performed on the TB. The processing circuitry entropy decodes the secondary transform index based on the context and performs the secondary transform.