Intra Block Copy Coding with Restricted Search Areas
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Solution Overview
Problem
Existing video coding technologies face inefficiencies in intra prediction, particularly in handling the large number of possible intra prediction directions and motion vector prediction, leading to suboptimal compression ratios and increased bit usage for less likely directions.
Innovation Solution
Implement Intra Block Copy (IntraBC) mode with search range restrictions, utilizing a first and second search area to identify candidate blocks for intra prediction, and decoding based on spatial relationships between these areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If IntraBC mode uses extensive search areas to find optimal prediction blocks, then prediction accuracy is improved, but computational complexity and processing time increase
Solution Approach 1:
The search area is divided into multiple candidate blocks that are evaluated in a specific order. The encoder examines blocks sequentially and stops when finding the first block that meets the matching criteria, rather than exhaustively searching all possible blocks. This segmentation of the search space reduces computational complexity while maintaining adequate prediction accuracy.
Solution Approach 2:
Instead of performing a complete exhaustive search of all possible candidate blocks, the encoder performs a partial search by evaluating blocks in order of likelihood and stopping early when satisfactory matching is achieved. This partial action approach reduces processing time and computational load while still obtaining sufficient prediction quality for most cases.
2Productivity
If IntraBC mode searches all possible candidate blocks for optimal prediction, then compression ratio is improved, but processing time and complexity increase
Solution Approach 1:
Candidate blocks are pre-sorted or pre-identified based on spatial proximity and likelihood of being good prediction sources before the actual matching process. This preliminary organization allows the encoder to quickly evaluate the most promising candidates first, achieving good compression ratios without exhaustively searching all possible blocks, thus reducing processing time.
Solution Approach 2:
The encoder adjusts search parameters such as maximum search depth, candidate block selection criteria, and matching thresholds dynamically based on content characteristics. By changing these parameters adaptively, the system achieves high compression ratios for complex regions while using more efficient limited search for simpler regions, optimizing the trade-off between compression performance and processing time.
Data Source
AI summary
This disclosure relates generally to video coding and particularly to intra block copy coding mode. An example method may include determining a first search area in a video frame, wherein the first search area is a first candidate area for locating IntraBC prediction block; determining a second search area, wherein the second search area is a second candidate area for locating the IntraBC prediction block, and the IntraBC prediction block overlapping with the second search area in a second overlap area of the IntraBC prediction block; selecting a target overlap area from the first overlap area and the second overlap area; replacing samples in the target overlap area to obtain an updated IntraBC prediction block; and encoding the at least the portion of the current block based on the updated IntraBC prediction block; encoding a block vector used for identifying the IntraBC prediction block.