Virtual Temporal Affine Candidates for Video Compression
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Solution Overview
Problem
Existing video compression systems face inefficiencies in creating virtual temporal affine candidates, requiring large memory storage for affine parameters, which is not feasible for hardware decoders, and lack adaptation for differing motion buffer resolutions.
Innovation Solution
The method involves determining control point motion vectors based on neighboring sub-blocks to generate a motion field for video blocks, allowing the creation of virtual temporal affine candidates without additional affine parameter storage and adapting to differing motion buffer resolutions by rescaling and selecting suitable sub-block motion vectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If virtual temporal affine candidates are created using traditional methods, then motion prediction accuracy is improved, but memory storage requirements for affine parameters increase significantly
Solution Approach 1:
The patent extracts only the essential motion information (control point motion vectors) from the affine parameters, storing only what is necessary for generating virtual temporal candidates. By separating the critical motion vectors from the complete affine parameter set, the solution reduces memory storage requirements while maintaining the capability to generate accurate motion predictions.
Solution Approach 2:
The patent creates virtual temporal affine candidates by copying and adapting motion information from co-located blocks in reference pictures. Instead of storing complete affine parameters for all blocks, the system copies motion vectors from previously decoded blocks and reconstructs affine candidates on-demand, significantly reducing memory requirements while preserving prediction accuracy.
2Measurement precision
If affine parameters are stored for all blocks, then candidate selection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent performs preliminary action by preparing and storing only the essential control point motion vectors in advance, rather than storing complete affine parameters. This preliminary preparation of minimal necessary data reduces the complexity of hardware decoders while maintaining the ability to generate accurate affine candidates when needed.
Solution Approach 2:
The system enables self-service by allowing the decoder to generate virtual temporal affine candidates on-demand using stored motion vectors and standard affine calculations. Instead of requiring complex pre-computed affine parameters for all blocks, the decoder serves itself by reconstructing candidates as needed from basic motion vector storage.
3Measurement precision
If motion buffer resolution is increased, then motion vector precision is improved, but memory requirements and processing complexity increase
Solution Approach 1:
The patent applies local quality by using higher precision motion vectors only where necessary (in the motion buffer for reference blocks) and accepting lower precision for virtual temporal candidate generation. By differentiating precision requirements between different stages of processing and different spatial locations, the system maintains motion vector precision where critical while reducing overall memory requirements.
Data Source
AI summary
A video encoder or decoder processes portions of video using virtual temporal affine motion candidates. Under the general aspects, virtual temporal affine candidates are created using only the classical temporal motion buffer information, avoiding the storage of additional affine parameters in a temporal motion buffer. A motion field for encoding or decoding a video block is generated based on the virtual temporal affine candidates. In one embodiment, collocated motion candidates are rescaled by adjusting the picture order count of the determined motion field. In another embodiment, resolution adaptation is performed to enable a current motion buffer to correspond to a reference motion buffer.