Intra Block Copy BVD Signaling Using Reference Region Constraints
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing video coding technologies face challenges in efficiently encoding and decoding video sequences due to the large data size, and they often overlook differences in signaling overhead between intra block copy (IBC) mode and inter prediction, leading to suboptimal compression efficiency.
Innovation Solution
The proposed solution involves directly exploiting the IBC reference region constraint to conditionally signal the sign of one or both directional components of a block vector difference (BVD) in the bitstream, thereby reducing the signaling overhead of IBC prediction information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If traditional signaling methods are used for IBC mode, then prediction accuracy is maintained, but signaling overhead is excessive
Solution Approach 1:
The patent extracts only the essential sign information of the block vector difference components and signals only those signs that are not determined by the reference region constraint. This selective extraction reduces signaling overhead while maintaining complete prediction information, as the reference region constraint automatically determines the signs of vectors pointing to valid reference blocks.
Solution Approach 2:
The reference region constraint itself serves to determine the sign of the block vector difference components. Instead of requiring explicit signaling for all sign information, the system uses the constraint logic to self-determine which signs are fixed, thereby reducing the signaling burden and optimizing bitstream efficiency.
2Loss of information
If block vector difference signaling is simplified, then signaling overhead is reduced, but prediction precision may be compromised
Solution Approach 1:
The patent segments the sign determination process into two parts: (1) signs that are automatically determined by the reference region constraint, and (2) signs that require explicit signaling. This segmentation allows the system to signal only the necessary information while maintaining complete prediction precision, as the constraint-based determination provides implicit sign information for valid reference blocks.
3Productivity
If IBC mode is implemented without optimization, then implementation simplicity is maintained, but compression efficiency is suboptimal
Solution Approach 1:
The patent changes the parameter of sign signaling from explicit full-signaling to conditional sign signaling based on the reference region constraint. This parameter change optimizes compression efficiency by reducing the number of signaled bits, while the complexity increase is minimal since it only affects the signaling logic rather than the core IBC prediction mechanism.
Data Source
AI summary
A decoder receives, in a bitstream, an indication of a block vector predictor (BVP) and a first and a second component magnitude of a block vector difference (BVD). The decoder determines each of a plurality of BV candidates based on a sum of the BVP and a different one of a plurality of BVD candidates. Each of the plurality of BVD candidates comprises: the first and second component magnitudes; and a different combination of signs for the first and second component magnitudes. The decoder determines a sign for at least one of the first and second component magnitudes of the BVD based on validities of the plurality of BV candidates.