Constrained Coding Tree Split Rules for Faster Video Coding
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Solution Overview
Problem
Existing video coding technologies face challenges in efficiently partitioning coding tree units (CTUs) without breaking pipeline structures, leading to coding slowdowns and inefficiencies.
Innovation Solution
Implementing a constrained coding tree that restricts split modes based on maximum transform unit (TU) dimensions to prevent CTU partitioning across pipeline block boundaries, using quad-tree, horizontal binary-tree, and no split modes for specific dimensions, and signaling these modes with flags.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If CTU partitioning is performed without constraints on split modes, then coding flexibility is improved, but pipeline structure is broken causing coding slowdowns
Solution Approach 1:
The patent segments the CTU partitioning process into distinct cases based on coding tree node dimensions relative to maximum TU dimensions. By dividing the partitioning logic into specific dimensional categories (e.g., when height is twice max TU height and width is twice max TU width), the patent enables targeted application of appropriate split modes that maintain pipeline structure while preserving necessary coding flexibility for different block sizes.
Solution Approach 2:
The patent applies different split mode constraints to different local regions of the CTU based on their dimensional characteristics. Specifically, coding tree nodes with dimensions matching certain multiples of maximum TU dimensions are restricted to specific split modes (quad-tree, horizontal binary-tree, or no split), while other regions may use different modes. This localized quality approach ensures pipeline integrity is maintained where needed without unnecessarily constraining other areas.
2Productivity
If constrained coding tree is applied to prevent CU partitioning across pipeline block boundaries, then coding speed is improved, but coding flexibility is reduced
Solution Approach 1:
The patent implements dynamic split mode selection based on the dimensional relationship between coding tree nodes and maximum transform units. The constraints on split modes are not fixed but adapt according to the specific dimensions of each coding tree node. When dimensions align with certain multiples of maximum TU dimensions, specific split modes are permitted; otherwise, different modes become available. This dynamic approach maintains pipeline structure while preserving coding flexibility where dimensional constraints do not apply.
3Stability of the object's composition
If split modes are restricted based on maximum TU dimensions, then pipeline structure is maintained, but signaling overhead increases
Solution Approach 1:
The patent changes the parameters governing split mode selection based on the dimensional relationship between coding tree nodes and maximum transform units. By establishing specific parameter thresholds (e.g., when height equals twice max TU height and width equals twice max TU width), the patent enables deterministic selection of permissible split modes. This parameter-based approach maintains pipeline structure stability while reducing signaling overhead through implicit rules that eliminate the need to signal all possible split mode combinations.
Data Source
AI summary
A video coding mechanism is disclosed. The mechanism includes partitioning an image to create at least one coding tree unit (CTU) with at least one coding tree node. The mechanism further includes determining that the coding tree node height is twice a maximum transform unit (TU) height and the coding tree node width is twice a maximum TU width. The mechanism further includes selecting a split mode for the coding tree node based on the determination. The split mode is selected from a quad-tree split, a horizontal binary-tree split, and no split. The mechanism further includes applying the split mode to the coding tree node to create one or more coding units (CUs). The mechanism further includes encoding the CUs into a bitstream. The mechanism further includes transmitting the bitstream toward a decoder.