Affine Motion Vector Clipping for Reliable Video Block Prediction
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Solution Overview
Problem
Existing video coding systems face issues with motion vectors that fall outside a certain range, leading to unintended consequences, particularly in block-based hybrid video coding systems.
Innovation Solution
Implement motion vector clipping for affine motion mode in video blocks, using control point affine motion vectors derived from neighboring blocks, and store clipped vectors for motion vector prediction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If motion vectors are used without clipping, then motion prediction accuracy is improved, but system reliability deteriorates due to unintended consequences from out-of-range values
Solution Approach 1:
The patent applies parameter changes by clipping motion vectors to a valid range based on bit depth. The clipping operation modifies the parameter values (motion vector components) to ensure they fall within acceptable boundaries, preventing out-of-range values while maintaining prediction accuracy for valid vectors.
2Reliability
If motion vectors are clipped based on bit depth, then system reliability is improved, but motion prediction precision deteriorates due to loss of vector information
Solution Approach 1:
The patent applies local quality by selectively clipping only those motion vectors that fall outside the valid range, while preserving the full precision of vectors within the acceptable range. This localized approach ensures that valid motion information is maintained without introducing unnecessary clipping artifacts.
3Device complexity
If control point affine motion vectors are derived from neighboring blocks, then device complexity is reduced, but measurement precision deteriorates due to potential error propagation
Solution Approach 1:
The patent applies feedback by clipping the derived control point affine motion vectors to ensure they fall within valid ranges before being stored and used for prediction. This feedback mechanism prevents error propagation by correcting out-of-range values that could otherwise compromise prediction precision in subsequent processing stages.
Data Source
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AI summary
Systems, methods, and instrumentalities are disclosed for motion vector clipping when affine motion mode is enabled for a video block. A video coding device may determine that an affine mode for a video block is enabled. The video coding device may determine a plurality of control point affine motion vectors associated with the video block. The video coding device may store the plurality of clipped control point affine motion vectors for motion vector prediction of a neighboring control point affine motion vector. The video coding device may derive a sub-block motion vector associated with a sub-block of the video block, clip the derived sub-block motion vector, and store it for spatial motion vector prediction or temporal motion vector prediction. For example, the video coding device may clip the derived sub-block motion vector based on a motion field range that may be based on a bit depth value.