CABAC Encoder Loop Unification for Transform-Skip Residual Coding
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Solution Overview
Problem
Existing video coding technologies face inefficiencies and increased complexity due to inappropriate encoding schemes for blocks with and without orthogonal transforms, leading to increased code amounts, processing delays, and circuit scale issues.
Innovation Solution
An encoder and decoder system that processes blocks with and without orthogonal transforms using a unified loop process for encoding and decoding coefficient information flags, reducing the number of loop processes and minimizing circuit scale by using context-based adaptive binary arithmetic coding (CABAC) with distinct context indices for coefficient and absolute value flags.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If different encoding schemes are used for blocks with and without orthogonal transforms, then coding accuracy can be optimized for each case, but device complexity and circuit scale increase
Solution Approach 1:
The patent merges the encoding processes for blocks with and without orthogonal transforms into a unified loop structure. The encoder uses a single encoding loop that handles both block types by adapting the context index selection based on the block type, rather than maintaining separate encoding loops. This reduces circuit scale while preserving coding accuracy through context-based adaptive binary arithmetic coding (CABAC) with dynamic context index adjustment.
Solution Approach 2:
The patent introduces dynamic context index adjustment within the unified encoding loop. The context index is adapted based on the block type (with or without orthogonal transform) and the characteristics of surrounding coefficients. This dynamic adaptation allows the encoder to optimize coding accuracy for different block types while maintaining a single, flexible encoding structure that avoids the complexity of separate fixed schemes.
2Manufacturing precision
If separate encoding loops are used for blocks with and without orthogonal transforms, then encoding precision can be improved, but processing time increases
Solution Approach 1:
The patent combines multiple separate encoding loops into a single unified loop that processes both block types. The unified loop includes conditional logic to adjust the context index based on whether the current block has undergone orthogonal transform. This merging eliminates the need to execute separate encoding loops sequentially, thereby reducing processing time while maintaining encoding precision through adaptive context selection.
Solution Approach 2:
The patent performs preliminary determination of the block type (with or without orthogonal transform) before entering the unified encoding loop. This preliminary action allows the encoder to pre-select or pre-adjust the context index based on the block type, enabling the unified loop to proceed efficiently without requiring separate processing paths. This reduces processing time by avoiding redundant loop iterations while preserving encoding precision.
3Productivity
If multiple loop processes are used to encode coefficient information flags, then coding efficiency can be improved, but the encoding process becomes more complex
Solution Approach 1:
The patent merges multiple encoding loop processes into a single unified loop that handles both coefficient information flags and absolute value flags. The unified loop uses context-based adaptive binary arithmetic coding (CABAC) with dynamic context index adjustment based on surrounding coefficients. This consolidation maintains coding efficiency by preserving the adaptive nature of the encoding while reducing the complexity of managing multiple separate loops.
Solution Approach 2:
The patent changes the parameter being adapted within the unified loop from separate encoding schemes to a dynamic context index. By adjusting the context index parameter based on the characteristics of surrounding coefficients and block type, the encoder achieves the benefits of multiple specialized loops without their structural complexity. This parameter-based adaptation simplifies the encoding process while maintaining high coding efficiency.
Data Source
AI summary
An encoder including circuitry and memory coupled to the circuitry. In a second type of residual coding among a first type of residual coding where an orthogonal transform is applied to a current block and the second type of residual coding where the orthogonal transform is skipped for the current block, wherein a first syntax used for the first type of residual coding is different from a second syntax used for the second type of residual coding, the circuitry: in a first loop process, derives a context index by using at least one of a plurality of surrounding coefficients; and encodes a plurality of coefficient information flags by CABAC with the derived context index; and in a second loop process of the plurality of loop processes, encodes a plurality of absolute value flags by CABAC with another context index.