Overlapped Optical Flow Motion Vector Refinement with Adaptive Subblocks
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Solution Overview
Problem
Existing video coding technologies face challenges in achieving accurate motion vector refinement, which affects the compression efficiency and quality of video data, particularly due to limitations in adapting subblock sizes during optical flow-based refinement.
Innovation Solution
Adaptive selection of subblock sizes for optical flow-based motion vector refinement, allowing for more samples to be used in the refinement process, thereby improving the accuracy of motion vectors without additional cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fixed subblock sizes are used for optical flow refinement, then the processing is simple and efficient, but the motion vector accuracy is insufficient
Solution Approach 1:
The patent applies dynamics by making subblock sizes adjustable rather than fixed. The encoder dynamically selects appropriate subblock sizes based on the characteristics of each block, allowing the system to adapt to varying motion patterns and improve motion vector accuracy without using a single rigid configuration throughout.
Solution Approach 2:
The patent changes the parameter of subblock size from a fixed value to a variable parameter that can be adapted. By allowing subblock sizes to change based on block characteristics and motion patterns, the system optimizes the balance between processing complexity and motion vector refinement accuracy.
2Measurement precision
If larger subblocks are used for optical flow refinement, then more samples are available for refinement, but the computational complexity increases
Solution Approach 1:
The patent applies local quality by using different subblock sizes appropriate to each local block's characteristics. Rather than uniformly applying large subblocks throughout, the system selects optimal subblock sizes for each block based on its content and motion patterns, providing localized optimization that balances accuracy and complexity.
Solution Approach 2:
The system dynamically adjusts subblock sizes based on the specific characteristics of each block being processed. This dynamic adaptation allows the system to use larger subblocks where more samples are needed for accuracy, while using smaller subblocks where computational resources should be conserved, thus balancing the trade-off between precision and complexity.
3Manufacturing precision
If adaptive subblock sizes are implemented, then motion vector accuracy improves, but the encoding complexity increases
Solution Approach 1:
The patent implements parameter changes by allowing subblock sizes to be adapted based on block characteristics. This enables the system to optimize coding accuracy for each block individually while managing encoding complexity through intelligent parameter selection rather than exhaustive search.
Solution Approach 2:
The system applies partial action by implementing adaptive subblock sizing selectively rather than universally. The encoder determines when and where adaptive subblock sizes provide benefit, applying them only to blocks where they improve coding accuracy, thus avoiding unnecessary complexity in cases where fixed sizes suffice.
Data Source
AI summary
An example method of video coding includes receiving a video bitstream comprising a plurality of blocks. The method also includes deriving a set of subblock motion vectors for a current block of the plurality of blocks and deriving a set of refined subblock motion vectors for the current block by applying an optical flow refinement on a set of subblocks of the current block. The respective sizes of the set of subblocks are adaptively selected for the optical flow refinement. The method further includes reconstructing the current block using the set of refined subblock motion vectors.