Diagonal Optical Flow for Video Motion Compensation
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Solution Overview
Problem
Current video coding technologies, such as HEVC and VVC, face inefficiencies in motion compensation and prediction refinement due to reliance on horizontal and vertical optical flows, which may not align with the true directional optical flows in video data, leading to suboptimal compression and decoding performance.
Innovation Solution
The proposed solution involves determining directional optical flows that are exclusive of horizontal and vertical directions for motion refinement and prediction processes in video coding. This includes using optical flows derived along diagonal and anti-diagonal directions, and combining multiple prediction refinements to generate a final prediction refinement, which can vary across different regions of a video block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If horizontal and vertical optical flows are used for motion compensation, then the implementation is simple and standardized, but the accuracy of motion prediction deteriorates when the true motion direction is diagonal or non-axis-aligned
Solution Approach 1:
The patent divides the optical flow calculation into multiple directional components (horizontal, vertical, and diagonal directions) rather than calculating a single comprehensive flow. This segmentation allows the system to process simpler directional flows separately and combine them, improving accuracy for diagonal motions while maintaining manageable computational complexity for each component.
Solution Approach 2:
The patent extends the traditional two-dimensional optical flow calculation by adding diagonal dimension components. Instead of only calculating horizontal and vertical flows, the system incorporates diagonal directional flows, effectively adding another dimensional aspect to the motion analysis, which improves prediction accuracy for non-axis-aligned motions.
2Measurement precision
If multiple directional optical flows are calculated and combined, then the prediction refinement accuracy improves, but the computational complexity increases
Solution Approach 1:
The patent applies different directional optical flows selectively to different regions or blocks of the video data based on local motion characteristics. Instead of uniformly applying all directional flows to every block, the system determines the appropriate directional flows for each local region, improving prediction accuracy where needed while reducing unnecessary computations in regions where simpler models suffice.
3Measurement precision
If directional optical flows exclusive of horizontal and vertical directions are used, then the alignment with true directional optical flows improves, but the compatibility with existing video coding standards deteriorates
Solution Approach 1:
The patent implements a dynamic selection mechanism that adapts the directional flow calculation based on the specific video content and motion characteristics. The system can dynamically determine whether to use traditional horizontal-vertical flows or incorporate diagonal directional flows, providing adaptability to both existing standards and improved directional accuracy depending on the scene requirements.
Data Source
AI summary
Motion compensation along different directions is disclosed. A method for video processing includes determining, for a conversion between a current video block of a video and a bitstream representation of the current video block, optical flow associated with the current video block in an optical flow-based motion refinement process or prediction process. The optical flow is derived along directions that are different from a horizontal direction and/or a vertical direction. The method also includes performing the conversion based on the optical flow.