Intra Block Copy Motion Vector Legality Check
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Solution Overview
Problem
Existing video coding technologies face challenges in efficiently handling motion vectors that are not legal for intra block copy (IBC) mode, leading to difficulties in predicting sample values for video blocks, particularly when the displacement vector does not reference a valid area within the same picture.
Innovation Solution
The proposed solution involves determining whether a motion vector for a current block in IBC mode is legal and, if not, employing alternative processing methods to reconstruct the block's samples, such as using default values or intra prediction modes, to ensure effective coding and decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a motion vector is used for IBC mode coding, then prediction accuracy is improved, but the system fails when the motion vector is not legal (does not reference a valid area)
Solution Approach 1:
The patent applies preliminary action by checking the legality of the motion vector before using it for prediction. The encoder/decoder determines whether the motion vector references a valid area within the same picture before attempting to use it for sample value prediction, preventing errors from occurring in the first place
Solution Approach 2:
The patent implements beforehand cushioning by preparing alternative processing methods in advance. When a motion vector is determined to be illegal, the system has pre-defined fallback mechanisms (such as using default values or alternative prediction modes) ready to ensure continuous operation without compromising reliability
2Reliability
If alternative processing methods are used for illegal motion vectors, then coding reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by implementing alternative processing methods only where needed - specifically when a motion vector is determined to be illegal. The system maintains the simple IBC prediction process for valid motion vectors while applying more complex alternative methods locally only to blocks with illegal motion vectors, minimizing overall complexity increase
Solution Approach 2:
The patent uses parameter changes by switching between different processing modes based on the legality of the motion vector. The system changes the prediction mode parameter from standard IBC prediction to alternative methods (such as using default values) when the motion vector is illegal, allowing flexible adaptation without permanently increasing complexity
Data Source
AI summary
An example method for coding video data includes determining, for a current block of a current picture of video data, the current block coded using an intra block copy (IBC) mode, whether a motion vector (MV) for identifying a prediction block for the current block is a legal MV. The example method further includes, responsive to determining that the MV is not a legal MV, reconstructing samples of the current block using an alternative processing method.