Coding Tree Partitioning Depth for Video Compression
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Solution Overview
Problem
Existing video encoding and decoding technologies, such as those in the VVC standard, lack flexibility in coding tree partitioning, which can lead to sub-optimal compression efficiency due to restricted maximum allowed hierarchy depth for multi-type trees.
Innovation Solution
The proposed solution involves increasing the maximum allowed hierarchy depth for multi-type trees (MTT) to twice the difference between the Coding Tree Unit (CTU) size and the minimum allowed size for a Coding Unit (CU), and allowing more flexibility in split tree configurations by signaling different maximum depths for various quadtree levels and components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the maximum allowed MTT hierarchy depth is increased to twice the difference between CTU size and minimum CU size, then the set of reachable coding tree nodes and leaves is increased, improving compression efficiency, but the device complexity and processing overhead increase
Solution Approach 1:
The patent applies dynamics by making the maximum MTT hierarchy depth configurable and adaptable rather than fixed. The depth parameter can be adjusted based on CTU size and minimum CU size requirements, allowing the coding system to dynamically optimize its structure for different video content and resolution requirements, thereby improving compression efficiency without permanently increasing inherent system complexity
Solution Approach 2:
The patent changes the parameter of maximum MTT hierarchy depth from a fixed value to a calculated value based on the formula: twice the difference between CTU size and minimum CU size. This parameter change allows the system to reach more coding tree nodes and leaves, improving compression efficiency while maintaining a systematic approach to managing complexity through mathematical relationships
2Adaptability or versatility
If different maximum depths are signaled for various QT levels and components (luma/chroma, intra/inter slices), then flexibility in partitioning is improved, but the signaling overhead and processing complexity increase
Solution Approach 1:
The patent applies local quality by allowing different maximum MTT hierarchy depths to be signaled for different QT levels, components (luma and chroma), and slice types (intra and inter). This enables each region and component to have optimized partitioning flexibility tailored to its specific characteristics, improving adaptability while concentrating signaling overhead only where differentiation is needed rather than applying uniform constraints everywhere
Solution Approach 2:
The patent segments the signaling of maximum MTT depth into separate parameters for different QT levels and components. Instead of a single global parameter, the system divides the configuration into multiple localized parameters that can be independently optimized, reducing the overall signaling overhead compared to a fully explicit approach while maintaining fine-grained control
Data Source
AI summary
To encode a picture, a coding tree unit (CTU) in the picture is partitioned by a quadtree structure, and the quadtree leaf nodes can be further partitioned by a multi-type tree (MTT) structure. To increase the set of reachable coding tree nodes and leaves, we propose to increase the maximum allowed MTT hierarchy depth to be twice the difference between the CTU size and the minimum allowed size for a CU. The maximum allowed MTT hierarchy depth can be specified for all QT levels in order to provide more flexibility in the split tree. Alternatively, only two levels of maximum allowed MTT depth are signaled: one when QT splits are allowed, and another one when no more QT splits are allowed. In addition, an upper bound can be set for the minimum 10 allowed coding block size, based on the coding tree unit size or the maximum allowed transform size.