Subblock Motion Compensation With Overlapped Boundary Prediction
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Solution Overview
Problem
Existing video coding technologies face challenges in accurately predicting motion vectors at block and subblock boundaries, leading to inefficiencies in compression and potential quality degradation, particularly when discontinuities occur.
Innovation Solution
Applying overlapped block motion compensation at subblock boundaries, using weighted averaging of motion vectors to refine prediction accuracy for blocks and subblocks, including local and global warp motion, bidirectional optical flow, and temporal interpolated prediction modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If subblock motion compensation is used with different motion vectors at subblock level, then motion prediction accuracy is improved, but complexity of motion compensation increases
Solution Approach 1:
The current block is divided into subblocks, and each subblock is assigned a different motion vector from the set of candidate motion vectors. This segmentation allows the system to capture motion variations within the block more accurately without requiring a single complex motion model for the entire block.
Solution Approach 2:
Different regions (subblocks) of the current block are assigned different motion characteristics (motion vectors) based on local motion patterns. This local quality approach improves prediction accuracy by adapting to spatial variations in motion while keeping the overall complexity manageable through a limited set of candidate vectors.
2Measurement precision
If overlapped block motion compensation is applied at subblock boundaries, then prediction accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent combines subblock motion compensation with overlapped block motion compensation by integrating the two techniques. The motion compensation process merges predictions from multiple motion vectors at block and subblock boundaries, improving accuracy at discontinuities while sharing computational resources between the two approaches.
Solution Approach 2:
The patent applies asymmetric treatment to different regions by using different motion vectors for different subblocks and applying overlapped compensation specifically at boundaries where motion discontinuities are expected. This asymmetric approach targets computational resources to where they are most needed rather than uniformly across the entire block.
3Productivity
If multiple candidate motion vectors are used for different subblocks, then compression efficiency is improved, but data processing requirements increase
Solution Approach 1:
Instead of allowing unlimited motion vectors for each subblock, the patent limits the choice to a predefined set of candidate motion vectors. This partial action approach provides sufficient flexibility to capture motion variations for good compression efficiency while constraining the search space to manageable data processing requirements.
Data Source
AI summary
The implementations described herein include methods and systems for coding video. In one aspect, a method includes receiving a current frame including a current coding block. The current coding block has multiple subblocks. The subblocks are associated with different motion vectors, and include a first subblock located at a boundary of the current coding block. The method includes determining a motion vector of the current coding block, determining a first motion vector of the first subblock, and generating motion compensation data of the first subblock based on the motion vector and the first motion vector of the first subblock, e.g., by identifying a prediction block based on the motion vector of the current coding block, identifying a first prediction block based on the first motion vector of the first subblock, and combining the prediction block and the first prediction block to generate the motion compensation data of the first subblock.