Video Coding Syntax for Affine and Sub-Block Motion Prediction
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Solution Overview
Problem
The increasing demand for high resolution and high quality images/videos, particularly in virtual reality and augmented reality, requires more efficient compression techniques to reduce transmission and storage costs, as existing methods struggle with the increased data volume.
Innovation Solution
Improving image coding efficiency through high and low level syntax design, including motion prediction based on sub-blocks and affine models, using flags like sps_affine_enabled_flag and sps_sbtmvp_enabled_flag to determine merge modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional compression techniques are used for high resolution images/videos, then transmission and storage costs increase, but image quality and resolution requirements cannot be met
Solution Approach 1:
The current block is divided into multiple sub-blocks for independent motion prediction. Each sub-block can have its own motion vector and prediction mode, allowing more precise representation of motion in high resolution videos without requiring excessive bits for the entire block
Solution Approach 2:
The patent introduces syntax elements like sps_affine_enabled_flag and sps_sbtmvp_enabled_flag to dynamically control prediction parameters. By conditionally enabling affine motion compensation and sub-block temporal motion vector prediction based on block characteristics, the system adapts compression parameters to reduce data volume while maintaining quality
2Productivity
If motion prediction based on sub-blocks and affine models is implemented, then coding efficiency improves, but syntax complexity increases
Solution Approach 1:
The patent employs dynamic syntax elements that are conditionally decoded based on flags. The sps_affine_enabled_flag and sps_sbtmvp_enabled_flag control whether affine motion compensation and sub-block TMVP syntax are present in the bitstream. This dynamic structure allows the decoder to adapt complexity to actual content needs, improving coding efficiency without universally increasing syntax complexity
Solution Approach 2:
Different prediction methods (affine motion compensation, sub-block TMVP, conventional prediction) are applied to different regions or blocks based on their characteristics. The syntax design allows selective application of complex methods only where beneficial, rather than applying them uniformly across all blocks, thus balancing coding efficiency with syntax complexity
3Productivity
If high level syntax elements are used for motion prediction control, then image coding efficiency improves, but processing overhead increases
Solution Approach 1:
Motion prediction parameters and syntax elements are prepared and organized at higher levels (sequence parameter set, picture parameter set) before actual decoding. The sps_affine_enabled_flag and related syntax are established in advance, allowing faster decoding at the block level without repeated complex decisions, thus improving coding efficiency while managing processing overhead
Data Source
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AI summary
An image decoding method performed by a decoding apparatus according to the present disclosure comprises the steps of: decoding, on the basis of a bitstream, an affine flag that indicates whether affine prediction is applicable to a current block and a sub-block TMVP flag that indicates whether a temporal motion vector predictor based on a sub-block of the current block is usable; determining whether to decode a predetermined merge mode flag that indicates whether to apply a predetermined merge mode to the current block, on the basis of the decoded affine flag and the decoded sub-block TMVP flag; deriving prediction samples of the current block on the basis of the determining of whether to decode the predetermined merge mode flag; and generating reconstructed samples of the current block based on the prediction samples of the current block.