IBC Buffer Edge Constraints for Video Coding
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Solution Overview
Problem
Intra picture block compensation in video coding faces challenges in setting block vectors to ensure that reference sample locations do not correspond to both the first and second horizontal edges of the IBC buffer, which affects the effective search range and memory usage for reference samples.
Innovation Solution
The method involves setting a block vector to indicate an offset between a current block and a reference block within the current picture, ensuring that reference sample locations do not align with both edges of the IBC buffer, and performing intra block copy (IBC) based on this constraint, while extending the search range of IBC mode and maintaining memory efficiency by storing reference samples across multiple coding tree units (CTUs).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the block vector search range is extended to include reference samples from both horizontal edges of the IBC buffer, then the search range of IBC mode is increased, but the reference samples may wrap around incorrectly causing coding errors
Solution Approach 1:
The patent divides the IBC buffer into two separate horizontal regions: a first horizontal region for storing reference samples from the first horizontal edge, and a second horizontal region for storing reference samples from the second horizontal edge. This segmentation prevents wrap-around errors by ensuring that reference samples are stored in their correct regional locations, while still allowing the block vector to search across the entire buffer range.
Solution Approach 2:
The patent applies different storage rules to different regions of the IBC buffer. The first horizontal region and second horizontal region are treated differently, with each region having its own designated area for reference sample storage. This local quality approach allows the system to maintain reliability in each region while achieving extended search range across the entire buffer.
2Adaptability or versatility
If reference samples are stored in a dedicated IBC buffer, then the search range is extended, but the memory requirements increase
Solution Approach 1:
The patent merges the storage of reference samples from both the first and second horizontal edges into a single dedicated IBC buffer, organized into first and second horizontal regions. This combining approach allows the system to extend the search range across the entire buffer while efficiently utilizing memory space, avoiding the need for separate buffer allocations for each edge.
3Reliability
If the block vector points to reference samples at horizontal edges of the IBC buffer, then the reference block may be unavailable or incorrectly reconstructed, but restricting the block vector limits the search range
Solution Approach 1:
The patent segments the IBC buffer into distinct first and second horizontal regions, with each region dedicated to storing reference samples from a specific horizontal edge. This segmentation ensures that when a block vector points to reference samples, the samples are correctly associated with their source edge, preventing reconstruction errors while maintaining extended search capability.
Data Source
AI summary
A method for setting a block vector for intra block copy (IBC) may include setting the block vector that indicates an offset between a current block in a current picture and a reference block in the current picture to satisfy a constraint that locations of reference samples of the reference block stored in an IBC buffer do not correspond to both of a first horizontal edge of the IBC buffer and a second horizontal edge of the IBC buffer; and performing IBC based on setting the block vector to satisfy the constraint.