Affine Motion Vector Clipping for EIF Memory Bandwidth Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing video coding technologies face challenges in efficiently managing memory bandwidth while maintaining high video quality, particularly in scenarios with dominant rotational motion, leading to inefficiencies and quality degradation.
Innovation Solution
Implement an enhanced interpolation filter (EIF) for motion compensation, which includes determining control point motion vectors and applying motion vector clipping based on predefined thresholds to optimize memory usage and improve coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If enhanced interpolation filter (EIF) is applied for motion compensation with pixel-based motion vector field, then video coding efficiency is improved, but memory bandwidth consumption increases
Solution Approach 1:
The patent applies motion vector clipping selectively based on local conditions - specifically when the reference area exceeds a threshold value. Different clipping strategies are applied to different regions (affine blocks versus non-affine blocks, and different sub-block sizes) rather than uniformly across the entire video stream, optimizing the balance between coding efficiency and memory bandwidth usage.
Solution Approach 2:
The patent dynamically adjusts motion vector parameters through clipping operations. When the reference area is larger than the threshold, motion vectors are clipped to a reduced range, effectively changing the parameter space of motion compensation. This adaptive parameter adjustment allows the system to maintain coding efficiency for complex motions while reducing memory bandwidth for simpler cases.
2Quantity of substance
If motion vector clipping is applied to reduce memory bandwidth, then memory bandwidth consumption is reduced, but picture quality may degrade
Solution Approach 1:
The patent applies motion vector clipping partially - not to all blocks but only to those where the reference area exceeds the threshold. This selective application ensures that clipping is performed only when necessary to reduce memory bandwidth, while preserving full motion vector precision for blocks where it does not exceed the threshold, thus maintaining picture quality where possible.
Solution Approach 2:
The patent segments the video processing into different handling strategies based on block type (affine versus non-affine) and reference area size. By dividing the processing into these segments, the system can apply aggressive clipping only where appropriate while maintaining higher quality processing elsewhere, thus resolving the quality-bandwidth tradeoff.
3Productivity
If affine inter-prediction with control point motion vectors is used for rotational motion, then coding efficiency is improved, but reference area increases leading to higher memory bandwidth requirements
Solution Approach 1:
The patent introduces dynamic adjustment of the motion vector search space through clipping. The effective reference area is dynamically reduced based on the calculated threshold, allowing the system to adaptively manage memory bandwidth requirements while maintaining the benefits of affine inter-prediction for rotational motion scenarios.
Data Source
AI summary
A method for coding a video implemented in an encoder or a decoder including the enhanced interpolation filter, EIF, for motion compensation, the method comprising: i) determining control point motion vectors, CPMVs, for a block according to affine inter-prediction, the block being an affine block or a sub-block of the affine block; ii) for a predefined sub-block size determining a reference area for a sub-block with the predefined sub-block size according to values of the CPMVs; iii) comparing the determined reference area with a predefined threshold; iv) applying EIF for motion compensation, comprising deriving the pixel-based motion vector field for the block; wherein if the determined reference area is larger than the threshold, deriving the pixel-based motion vector field for the block further comprises motion vector clipping, wherein motion vector clipping range is determined based on motion model of the block and the size of the block.