Intra Block Copy Mode Block Vector Prediction
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Solution Overview
Problem
Current video coding techniques for Intra-block copy (IntraBC) mode in HEVC standard face inefficiencies in block vector (BV) prediction, leading to substantial data requirements and suboptimal coding performance, especially for screen content coding.
Innovation Solution
The method involves generating multiple BV candidate lists from neighboring blocks using position-related priority orders and default values, with the option to include temporal and stored BVs, to select an effective BV predictor for the current block, thereby improving BV prediction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple BV candidate lists are generated from neighboring blocks with position-related priority orders, then coding efficiency is improved and bit-rate is reduced, but device complexity increases
Solution Approach 1:
The patent segments the BV prediction process by dividing candidate blocks into multiple priority-based lists (List 0 and List 1) with different position-related priority orders. List 0 checks positions in one priority order while List 1 checks in another order, allowing the system to search through organized segments of candidate blocks rather than treating all candidates uniformly, thereby improving coding efficiency while managing complexity through structured organization
Solution Approach 2:
The patent applies preliminary action by pre-establishing multiple candidate lists with predetermined priority orders before the actual BV selection process. The lists are constructed in advance with specific position priorities assigned, so that during encoding/decoding, the system can directly utilize these pre-organized lists without performing complex real-time searches, thus improving efficiency while controlling device complexity
2Productivity
If IntraBC mode is used for screen content coding, then coding performance is improved, but substantial data requirements increase bit-rate
Solution Approach 1:
The patent implements feedback by using previously coded neighboring blocks' BV information to predict the current block's BV. The system checks candidate blocks in priority order and uses their BV values as predictors, creating a feedback loop where past coding results inform current predictions. This reduces the amount of new data that needs to be transmitted, thereby reducing bit-rate while maintaining improved coding performance for screen content
3Device complexity
If BV prediction uses limited candidate blocks, then device complexity is reduced, but coding efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by making the candidate selection process adaptive rather than static. The system dynamically adjusts which candidates are considered by using multiple lists with different priority orders, allowing flexibility in searching through more candidates when needed while maintaining simplicity when sufficient candidates are found early in the search process. This dynamic approach balances device complexity with coding efficiency
Data Source
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AI summary
A method of block vector (BV) prediction for an IntraBC mode (Intra-block copy mode) coded block in a video coding system according to the present invention is disclosed. Multiple BV candidate lists are derived from neighboring blocks of the current block. A BV candidate list is selected as a BV predictor for the BV of the current block. The current block is coded based on an Intra reference block located according to the BV of the current block. In one embodiment， a left-bottom (LB) block of the current block is used to derive the first BV candidate list and an above-right (AR) block of the current block is used to derive the second BV candidate list. A 1-bit index code is signaled to select a BV predictor between the first BV candidate list and the second BV candidate list.