Motion Vector Encoding With Base-Delta Directional Prediction
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Solution Overview
Problem
Existing video coding standards like H.265/HEVC face challenges in achieving efficient inter prediction due to limitations in motion vector accuracy, which affects encoding efficiency.
Innovation Solution
An encoder and decoder implementation that determines a base motion vector and encodes/decodes a delta motion vector representing diagonal directions and distances, enhancing motion vector accuracy in inter prediction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional motion vector encoding is used in H.265/HEVC, then the encoding process is simple, but the motion vector accuracy is insufficient
Solution Approach 1:
The motion vector is segmented into a base motion vector and a delta motion vector. The base motion vector represents the primary motion direction, while the delta motion vector represents the difference from the base, allowing for more precise motion representation through directional and distance components.
Solution Approach 2:
The patent introduces a new dimensional representation for motion vectors by encoding direction and distance separately. Instead of using a single 2D vector component representation, the motion vector is expressed in terms of directional angles and radial distances, adding a polar coordinate dimension to the traditional Cartesian representation.
2Productivity
If higher-accuracy motion vectors are derived using delta motion vectors, then inter prediction efficiency is improved, but the data to be encoded increases
Solution Approach 1:
The patent changes the parameter representation of motion vectors from direct 2D components to directional and distance parameters. By transforming the motion vector into polar coordinates (direction angle and distance), the encoding can more efficiently represent motion patterns, reducing the effective data volume needed to achieve the same or better prediction accuracy.
Solution Approach 2:
The patent applies partial action by selectively encoding only the necessary components of the motion vector. Instead of encoding the full motion vector with high precision in all cases, the delta motion vector encodes only the directional and distance differences, providing sufficient accuracy for inter prediction while minimizing the data volume.
3Measurement precision
If diagonal directions are included in motion vector directions, then motion representation accuracy is improved, but the complexity of direction encoding increases
Solution Approach 1:
The patent introduces dynamic direction encoding where the number of direction bits is adjusted based on the magnitude of the motion vector. For larger motion vectors, more direction bits are allocated to achieve higher angular precision, while for smaller motion vectors, fewer bits are used. This dynamic allocation optimizes the balance between direction accuracy and encoding complexity.
Solution Approach 2:
The patent changes the direction encoding parameter from a fixed number of bits to a variable number of bits based on motion vector magnitude. By transforming the direction representation into a magnitude-dependent parameter, the system achieves higher directional accuracy for significant motions while maintaining efficiency for minor motions, effectively resolving the contradiction between precision and complexity.
Data Source
AI summary
An encoder includes: circuitry; and memory. Using the memory, the circuitry: in inter prediction for a current block, determines a base motion vector, and writes, in an encoded signal, a delta motion vector representing (i) one direction among a plurality of directions including a diagonal direction and (ii) a distance from the base motion vector; and encodes the current block using the delta motion vector and the base motion vector as a motion vector of the current block.