Video Encoder-Decoder Local Motion Estimation for Sub-Pixel Prediction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing video coding standards like HEVC face challenges in efficiently encoding and decoding video data, particularly in handling motion compensation and prediction processes, which can lead to inefficiencies and suboptimal performance.
Innovation Solution
An encoder and decoder system that utilizes motion vectors to derive local motion estimation values for sub-blocks based on pixel gradients, enabling sub-pixel accurate interpolation within a normal reference range, enhancing prediction accuracy and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If motion compensation is performed using conventional methods without local motion estimation, then the encoding process is simpler and faster, but prediction accuracy is insufficient leading to suboptimal compression efficiency
Solution Approach 1:
The patent divides the current block into multiple sub-blocks (e.g., four quadrants) and performs motion estimation independently for each sub-block. This segmentation allows the system to capture local motion variations while maintaining overall prediction accuracy, resolving the contradiction between precision and complexity by organizing the complex task into manageable segments.
Solution Approach 2:
The patent applies different motion estimation methods to different sub-blocks based on their specific characteristics. Each sub-block can have its motion vector derived using appropriate techniques (e.g., using reference block motion vectors or direct motion estimation), allowing the system to optimize prediction accuracy for each local region while managing overall computational complexity through targeted processing.
2Measurement precision
If local motion estimation is performed for each sub-block, then prediction accuracy improves, but processing time and computational load increase
Solution Approach 1:
The patent performs preliminary motion estimation at the block level before dividing into sub-blocks. Motion vectors are first derived for the entire current block using conventional motion estimation, and then these block-level motion vectors are used as starting points or constraints for sub-block level estimation. This preliminary action reduces the computational burden for sub-block processing while maintaining improved prediction accuracy.
Solution Approach 2:
The patent applies partial motion estimation to sub-blocks only when necessary, rather than uniformly processing all sub-blocks. The system can skip motion estimation for sub-blocks where the block-level motion vector is sufficient, or where motion characteristics indicate uniform movement. This selective approach reduces processing time while maintaining accuracy where needed.
3Measurement precision
If motion vectors are derived using conventional methods, then the reference range is simple and fixed, but sub-pixel accuracy cannot be achieved
Solution Approach 1:
The patent extends the reference range from a simple fixed area to a three-dimensional search space that includes temporal dimensions. By considering motion vectors and temporal relationships between frames, the system can achieve sub-pixel accuracy through optimized interpolation. The reference range is expanded to include not just spatial neighbors but also temporally related blocks, enabling more precise sub-pixel positioning.
Data Source
AI summary
An encoder that; obtains two prediction images by performing motion compensation using two motion vectors; obtains a gradient value of each of pixels included in the two prediction images; derives a local motion estimation value for each of sub-blocks based on the pixel value and the gradient value of each of the pixels, the sub-blocks being obtained by partitioning the current block; and generates a final prediction image for the current block using the pixel value and the gradient value of each of the pixels, and the local motion estimation value derived for each of the sub-blocks. Each of the pixels in the two prediction images is interpolated with sub-pixel accuracy, and a reference range for the interpolation is included in a normal reference range that is referred to for motion compensation for the current block in normal inter prediction performed without using the local motion estimation value.