Video Decoder Template Matching with Precision-Aligned Motion Refinement
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Solution Overview
Problem
Existing video decoding techniques introduce undesired complexity and rounding errors when starting motion vector refinement with a quarter-pel step size, leading to lower coding gain in certain scenarios.
Innovation Solution
Align the finest motion vector precision used in template matching with the motion vector precision being refined by iteratively reducing the step size from an initial step size until it equals the motion vector precision, ensuring refinement stops at the same precision as the motion vector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If motion vector refinement starts with a quarter-pel step size, then the search covers a broader area, but complexity and rounding errors increase
Solution Approach 1:
The patent applies dynamics by making the step size adaptive rather than fixed. The step size dynamically changes from an initial quarter-pel value to a final value that matches the motion vector precision, allowing the refinement process to adjust its granularity based on the specific requirements of each motion vector, thereby reducing unnecessary complexity while maintaining precision where needed
Solution Approach 2:
The patent changes the parameter of step size during the refinement process. By iteratively reducing the step size from an initial quarter-pel value to a final value equal to the motion vector precision, the patent optimizes the balance between search thoroughness and computational complexity, eliminating rounding errors that occur with fixed quarter-pel stepping
2Ease of manufacture
If motion vector refinement uses a fixed quarter-pel step size, then the process is simpler to implement, but rounding errors occur that reduce coding gain
Solution Approach 1:
The patent transforms the static quarter-pel step size into a dynamic parameter that adapts to the motion vector precision requirements. This dynamic adjustment maintains implementation feasibility while eliminating the rounding errors that degrade coding gain, as the step size automatically scales to match the required precision level
Solution Approach 2:
The patent modifies the step size parameter iteratively during refinement, changing it from a fixed quarter-pel value to a variable that converges to the motion vector precision. This parameter change eliminates systematic rounding errors while preserving the iterative refinement structure, thereby improving coding gain without sacrificing implementation simplicity
Data Source
AI summary
A video decoder may be configured to determine a motion vector and a motion vector precision for a current block; identify a current block template within the current picture; search within a search area for a final reference block template that corresponds to the current block template, wherein to search within the search area, the one or more processors are further configured to: identify an initial reference block template based on the motion vector, search other reference block templates around the initial reference block template using a step size that is set to an initial step size, and iteratively reduce the step size from the initial step size until the step size is set to a final step size that equals the motion vector precision; determine a prediction block for the current block based on the final reference block template.