Subblock Merge Candidates in Triangle Partition Video Coding
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Solution Overview
Problem
Existing video compression systems face limitations in achieving high compression efficiency for inter coded blocks, particularly in leveraging sub-block merge motion fields in Triangle and Geometric coding modes, where unidirectional candidates can only be derived from regular merge lists.
Innovation Solution
The proposed solution involves using sub-block merge candidates in Triangle and Geometric partition modes, signaling a flag to indicate the use of sub-block merge candidates, replacing regular merge candidates with sub-block ones, and storing motion fields accordingly, allowing for the consideration of all sub-block merge candidates or specific affine ones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regular merge lists are used for Triangle and Geometric coding modes, then the implementation is simple, but compression efficiency is limited
Solution Approach 1:
The patent segments the merge candidate list into two distinct parts: regular merge candidates and sub-block merge candidates. This segmentation allows the system to selectively use sub-block candidates for Triangle and Geometric partition modes while maintaining the original regular merge list for other modes, thereby improving compression efficiency for specific modes without unnecessarily complicating the overall system.
Solution Approach 2:
The patent applies local quality by introducing sub-block merge candidates that are specifically optimized for Triangle and Geometric partition modes. Instead of uniformly changing the candidate list structure for all modes, the solution locally enhances only the relevant modes by adding sub-block candidates derived from partitioning the current block into sub-blocks and selecting motion vectors from those sub-blocks.
2Loss of energy
If sub-block merge candidates are introduced for Triangle and Geometric modes, then compression performance improves, but computational complexity increases
Solution Approach 1:
The patent applies partial action by introducing sub-block merge candidates only for Triangle and Geometric partition modes, rather than for all inter prediction modes. This selective approach provides the compression performance benefits where needed while avoiding the computational overhead in modes where it is not required, thus balancing compression improvement with computational complexity.
3Loss of energy
If sub-block merge candidates are used, then motion compensation efficiency is enhanced, but signaling overhead increases
Solution Approach 1:
The patent introduces a dynamic flag (subblock_merge_triangle_flag or subblock_merge_geo_flag) that allows the encoder to selectively enable or disable sub-block merge candidates based on the partition mode being used. This dynamic approach ensures that sub-block candidates are only activated when beneficial (for Triangle and Geometric modes), avoiding unnecessary signaling overhead for other modes while maintaining motion compensation efficiency where needed.
Data Source
AI summary
Sub-block merge motion field is combined with triangle partitioning and geometric partitioning modes to further give coding and decoding schemes flexibility. In at least one embodiment, a flag is used to signal if sub-block merge candidates are used in place of regular merge candidates. In another embodiment, regular merge candidates are replaced by sub-block merge candidates. In another embodiment, at least one motion field is stored. In another embodiment, all sub-block merge candidates or only sub-block temporal motion vector predictors or only affine predictors are considered.