Sign Prediction Handling for Non-Dyadic Video Blocks
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Solution Overview
Problem
Current video coding technologies face challenges in efficiently handling sign prediction for non-dyadic blocks and chroma components, leading to incorrect operation of Low Frequency Non-Separable Secondary Transform (LFNST) and sign prediction mechanisms, particularly in scenarios involving dual-tree coding structures and transform skip residual coding.
Innovation Solution
The proposed solution involves determining sign prediction usage based on block dimensions, disallowing sign prediction for non-dyadic blocks, and modifying the signaling of LFNST indices based on color components and coding structures, ensuring correct operation of LFNST and sign prediction mechanisms across various block types and coding configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sign prediction is applied to non-dyadic blocks, then coding flexibility is improved, but processing complexity and errors increase
Solution Approach 1:
The patent applies different processing rules to different types of blocks: dyadic blocks receive sign prediction processing while non-dyadic blocks use alternative methods. This local differentiation resolves the contradiction by enabling flexible adaptation to various block types without uniformly increasing processing complexity across all blocks.
Solution Approach 2:
The patent segments the block processing into distinct paths based on block type (dyadic vs. non-dyadic). By dividing the processing logic into separate handling routines, the system achieves coding flexibility for different block types while managing complexity through structured segmentation rather than universal complex processing.
2Measurement precision
If LFNST is applied to chroma components in dual-tree coding, then transform accuracy is improved, but signaling complexity increases
Solution Approach 1:
The patent applies LFNST selectively to specific components (luma vs. chroma) and coding structures (dual-tree vs. single-tree) based on local requirements. This targeted application improves transform accuracy where needed while avoiding unnecessary signaling complexity in cases where LFNST is not applicable, thus resolving the contradiction between accuracy and signaling complexity.
3Productivity
If transform skip residual coding is used, then coding efficiency is improved, but operational correctness deteriorates
Solution Approach 1:
The patent dynamically adjusts the application of transform skip residual coding based on block characteristics and coding context. By making the transform skip operation conditional rather than universal, the system achieves coding efficiency improvements while maintaining operational correctness through adaptive control that prevents incorrect operations in unsuitable scenarios.
Data Source
AI summary
A mechanism for processing video data is disclosed. A sign prediction usage for one or more residual coefficients in a block is determined based on dimensions of the block. A conversion is then performed between a visual media data and a bitstream based on the residual coefficients in the block.