Overlapped Block Motion Compensation Using Sub-Block Uniformity
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Solution Overview
Problem
Current video coding systems face challenges in efficiently performing overlapped block motion compensation (OBMC) on coding blocks partitioned into sub-blocks, particularly in determining whether sub-blocks have similar motion fields and applying OBMC effectively in merge modes.
Innovation Solution
The proposed solution involves performing OBMC by considering sub-blocks as entire blocks if the motion field is uniform, using a block-based approach that determines similarity based on the sum of absolute differences and affine models, and applying OBMC in merge modes by subtracting top and left bands from the input signal for motion compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If OBMC is performed on sub-blocks individually, then motion compensation precision is improved, but processing complexity increases
Solution Approach 1:
The patent merges the processing of multiple sub-blocks by determining that they share the same motion field, allowing OBMC to be applied to the entire block rather than processing each sub-block separately. This reduces processing complexity while maintaining motion compensation precision through the unified motion field assumption.
Solution Approach 2:
The patent changes the parameter of motion field uniformity to determine whether sub-blocks can be processed together. By evaluating whether sub-blocks have substantially the same motion field (using sum of absolute differences), the system dynamically adjusts whether to apply OBMC at the sub-block or block level, optimizing the balance between precision and complexity.
2Measurement precision
If sub-blocks are treated as separate blocks for OBMC, then motion field accuracy is improved, but computational burden increases
Solution Approach 1:
The patent combines multiple sub-blocks into a single processing unit when they share the same motion field, reducing the computational burden by performing OBMC once for the entire block rather than multiple times for individual sub-blocks, while maintaining motion field accuracy through the uniform motion assumption.
Solution Approach 2:
The patent applies partial action by performing OBMC only when necessary (when sub-blocks have uniform motion fields), rather than always treating sub-blocks separately. This selective approach reduces computational burden while maintaining accuracy where needed.
3Productivity
If block-based OBMC is applied to partitioned blocks, then processing efficiency is improved, but motion field determination accuracy may worsen
Solution Approach 1:
The patent uses the parameter of sum of absolute differences to evaluate motion field similarity between sub-blocks. By thresholding this parameter, the system determines whether to apply block-based OBMC, ensuring that efficiency gains are achieved only when motion field determination accuracy is sufficient to justify the unified approach.
Data Source
AI summary
Systems, methods, and instrumentalities are disclosed for performing overlapped block motion compensation (OBMC). OBMC may be performed by considering sub-blocks within a coding block as an entire block if a motion field is uniform. OBMC may be performed on a coding block partitioned into multiple sub-blocks, using a block-based OBMC approach. The sub-blocks may be determined to have the same motion field, if the affine model associated with the block is translational. OBMC may be performed by subtracting OBMC from an original picture in the merge modes, using a block-based approach. A block coded in OBMC mode may be used in motion compensation, for example a fast merge pass of merge mode(s). The top band and the left band of the block may be subtracted from the input signal associated with the current block, and motion compensation may be performed on the block having the top and left bands subtracted.