Affine Motion Signaling for Complex Motion Video Coding
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Solution Overview
Problem
The existing video coding standards, such as HEVC, face challenges in efficiently handling complex motions like zoom, rotation, and perspective transformations due to the complexity and increased signal overhead associated with affine motion mode.
Innovation Solution
The method involves determining an inter prediction mode and signaling affine motion mode based on the status of a skip flag, enabling affine mode for certain conditions, and optimizing the use of affine motion mode through neighbor block analysis and context encoding to improve coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If affine motion mode is applied to handle complex motions, then motion prediction accuracy is improved, but encoding and decoding complexity increases
Solution Approach 1:
The patent applies affine motion mode selectively only to specific blocks that exhibit complex motion patterns (zoom, rotation, perspective), rather than uniformly to all blocks. The encoder determines whether to apply affine mode based on motion characteristics of neighboring blocks and merge candidate availability, ensuring complex processing is localized only where needed to improve prediction accuracy without unnecessarily increasing overall complexity.
Solution Approach 2:
The patent implements a conditional approach where affine motion mode is applied partially - only when beneficial conditions are met (neighboring blocks use affine mode, or merge candidates are available). This partial application strategy avoids the excessive complexity of universal affine mode while still capturing the accuracy benefits in regions where complex motion occurs.
2Productivity
If affine motion mode is applied to handle complex motions, then compression efficiency is improved, but signal overhead increases
Solution Approach 1:
The patent signals affine motion mode information locally only for blocks that require it, based on local motion characteristics and neighboring block patterns. Rather than signaling affine parameters for all blocks, the encoder uses context-based signaling that activates affine mode indicators only where neighboring blocks suggest complex motion patterns exist, reducing overall signal overhead while maintaining compression efficiency benefits where needed.
3Productivity
If affine motion mode is enabled based on neighboring block modes, then coding efficiency is improved, but processing complexity increases
Solution Approach 1:
The patent performs preliminary analysis of neighboring block modes during the encoding process to determine whether affine motion mode should be applied to the current block. By examining the motion modes of already-encoded neighboring blocks and merge candidate lists in advance, the encoder makes informed decisions about affine mode application before finalizing the current block encoding, improving coding efficiency through pattern recognition while managing processing complexity through systematic evaluation.
Data Source
AI summary
The invention relates to signalling affine mode in an encoded video stream; in particular determining a list of merge candidates corresponding to blocks neighbouring a current block; and signalling affine mode for said current block; wherein signalling said affine mode comprises decoding a context encoded flag from the data stream, and wherein the context variable for said flag is determined based on whether or not said neighbouring blocks use affine mode. Related encoding and decoding methods and devices are also disclosed.