Uneven Hexagon Search for H.264 Motion Estimation
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Solution Overview
Problem
H.264 motion estimation requires a large quantity of computations, taking up a significant portion of encoding time, making it challenging for real-time applications due to its complexity and computational intensity compared to earlier standards like MPEG-2 and MPEG-4.
Innovation Solution
The proposed solution involves a selective uneven multi-hexagon grid search (UMHGS) method that determines a quadrant for the predicted motion vector, calculates tilt values for reference frames, decides a search area based on these values, performs an uneven hexagon search within that area, and compares the results with a threshold to terminate the search early, reducing computational load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If H.264 motion estimation uses multiple reference images and various block modes, then compression efficiency is improved, but computational complexity increases significantly
Solution Approach 1:
The patent segments the search area into multiple quadrants based on the predicted motion vector direction. Instead of performing exhaustive search over the entire search area, the algorithm divides it into four quadrants and selectively searches only relevant quadrants, reducing the number of reference image blocks that need to be examined while maintaining compression efficiency
Solution Approach 2:
The patent applies different search strategies to different regions of the search space. By calculating tilt values and determining which quadrants are most likely to contain the optimal motion vector, the algorithm concentrates computational resources on locally relevant areas rather than uniformly processing the entire search area, thus reducing overall computational complexity
2Measurement precision
If H.264 motion estimation searches the entire search area, then motion estimation accuracy is improved, but encoding time increases
Solution Approach 1:
The patent performs preliminary calculations of tilt values for both current and previous reference frames before conducting the actual motion estimation search. These tilt values provide advance information about the likely direction and magnitude of motion, allowing the algorithm to pre-determine which quadrants to search and thereby reduce the time required for exhaustive search while maintaining accuracy
Solution Approach 2:
The patent performs partial search by examining only the necessary quadrants rather than the entire search area. By using tilt values to identify and focus on the most probable motion vector locations, the algorithm achieves sufficient motion estimation accuracy without the excessive computational effort required for complete area search
Data Source
AI summary
An image search method may include: determining a quadrant of a predicted motion vector; calculating a tilt value of a first reference frame and a tilt value of a second reference frame using the predicted motion vector; deciding a search area for uneven hexagon search in response to the quadrant of the predicted motion vector and the calculated tilt values; performing the uneven hexagon search with respect to the decided search area; and/or comparing a result of the performed uneven hexagon search with a threshold value to determine termination of the uneven hexagon search. The second reference frame is earlier-in-time relative to the first reference frame.