Flexible CTU Picture Partitioning for Boundary-Aligned Video Coding

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Solution Overview

Problem

Modern video coding standards, such as H.264/AVC, HEVC, VVC, and AV1, face inefficiencies in picture partitioning when object boundaries are not aligned with fixed partitioning, requiring additional bits to signal boundaries and motion, leading to increased data usage.

Innovation Solution

The method involves partitioning a coded picture into coding tree units (CTUs) where CTUs adjacent to the picture boundaries have smaller dimensions than those in the interior, allowing for adaptive signaling and restricting splitting types based on predetermined size thresholds to optimize bit usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If fixed-size CTUs are used for picture partitioning, then decoding simplicity is maintained, but additional bits are required to signal object boundaries and motion when object boundaries are not aligned with the fixed partitioning

Engineering Contradiction:

Improvebit usage for signaling boundary and motion informationVSAvoidpicture partitioning structure

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

The patent applies dynamics by making CTU sizes adaptive rather than fixed. The encoder can select from multiple CTU size options (e.g., 64×64, 128×128, 256×256) and adjust the partitioning structure based on content characteristics and object boundary alignment requirements, thereby reducing signaling overhead while maintaining decoding feasibility

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements local quality by allowing different CTU sizes in different regions of the picture. Areas with object boundaries can use smaller CTUs for precise alignment, while uniform areas can use larger CTUs for compression efficiency, optimizing bit usage locally rather than uniformly across the entire picture

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If smaller CTUs are used at picture boundaries, then alignment with object boundaries is improved, but the regularity of the partitioning structure is reduced

Engineering Contradiction:

Improvealignment with object boundariesVSAvoidpartitioning structure regularity

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent applies segmentation by dividing the picture into different CTU size regions. The first row or column of CTUs at the picture boundary can have a different size than the second row or column, creating segmented zones that accommodate object boundaries while maintaining overall structural organization through defined transition rules

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11800106B2Flexible picture partitioning

Publication Date: 2023.10.24 TENCENT AMERICA LLC

AI summary

Systems and methods may provide flexible picture partitioning, a method includes receiving a bitstream, that includes a picture, the picture partitioned into a plurality of coding tree units (CTUs), wherein at least one row or column of CTUs, among the plurality of CTUs of the picture, that is adjacent to a boundary of the picture has a size dimension that is smaller than a corresponding size dimension of each CTU among the plurality of CTUs that is not adjacent to any boundary of the picture; and encoding the bitstream based on the plurality of CTUs, wherein the at least one row or column of CTUs includes a first CTU row or a first CTU column of the picture that is adjacent to a top boundary or left boundary of the picture, respectively.