Motion Vector Candidate Reordering for Reference Picture Resampling
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Solution Overview
Problem
Existing video compression methods face limitations in achieving high compression efficiency when dealing with reference picture resampling, particularly when the reference picture size differs from the current image size, leading to reduced coding efficiency and codec consistency.
Innovation Solution
The proposed solution involves a method that obtains a list of motion vector candidates and associated reference indexes, assigns a cost to them, and reorders these candidates based on their costs, with options for default costs in cases of differing picture sizes, to enhance prediction and decoding processes in video coding systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If motion vector candidates are selected without reordering when reference picture size differs from current image size, then coding complexity is reduced, but coding efficiency deteriorates due to suboptimal prediction selection
Solution Approach 1:
The patent applies dynamics by making the motion vector candidate list reordering adaptive to the reference picture size condition. When the reference picture size equals the current image size, no reordering is performed. When they differ, reordering based on cost is applied. This dynamic adaptation resolves the contradiction by adjusting the processing level according to the specific condition, improving coding efficiency when needed while avoiding unnecessary complexity when not needed.
2Measurement precision
If motion vector candidates are reordered based on cost when reference picture size differs from current image size, then prediction accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent applies local quality by applying different processing treatments to different situations based on the reference picture size condition. For candidates where the reference picture size equals the current image size, no reordering is applied. For candidates where the sizes differ, cost-based reordering is applied. This localized approach ensures prediction accuracy is improved only where necessary, avoiding unnecessary computational complexity.
3Reliability
If default cost is assigned to motion vector candidates with different picture sizes, then codec consistency is maintained, but loss of information occurs in cost calculation accuracy
Solution Approach 1:
The patent applies this principle by using a simplified default cost value for motion vector candidates where the reference picture size differs from the current image size. Instead of performing complex and accurate cost calculations that would require additional information, a default cost is assigned. This disposable approach maintains codec consistency between encoder and decoder while accepting a controlled loss in cost calculation accuracy for these specific cases.
Data Source
AI summary
In a video coding system, it is proposed to adapt video coding tools to the use of Reference Picture Re-scaling where a reference picture has a different size than the current picture to be coded or decoded. Different embodiments are proposed hereafter, introducing some tools modifications to increase coding efficiency and improve the codec consistency when RPR is enabled. A video encoding method, a decoding method, a video encoder and a video decoder are described.