Angular Intra Prediction With Delta-Angle Mode Switching
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Solution Overview
Problem
Existing video coding technologies face inefficiencies in handling directional intra prediction modes with angles between 90 and 180 degrees, particularly in content with sharp edges, as they often rely on suboptimal bi-directional intra prediction methods.
Innovation Solution
Implementing a method that applies single direction intra prediction when the delta angle is not a predefined value (0, 2, or −2 degrees) and bi-direction intra prediction when the delta angle is predefined, using a mapping table to determine the appropriate intra directional mode and reference lines for improved prediction accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bi-directional intra prediction is applied to directional modes with angles between 90 and 180 degrees, then prediction coverage is improved, but decoding complexity increases
Solution Approach 1:
The patent applies parameter changes by using a delta angle parameter to determine the prediction mode. When the delta angle equals a predefined value, bi-directional intra prediction is used; otherwise, single direction intra prediction is applied. This parameter-based decision mechanism resolves the contradiction by dynamically selecting the appropriate prediction method based on content characteristics, thereby maintaining prediction accuracy while reducing unnecessary decoding complexity.
2Device complexity
If single direction intra prediction is used for all directional modes, then decoding complexity is reduced, but prediction accuracy deteriorates for certain angle ranges
Solution Approach 1:
The patent implements dynamics by making the prediction mode adaptive rather than static. The system dynamically switches between single direction and bi-directional intra prediction based on the delta angle value. This dynamic adaptation ensures that the most appropriate prediction method is used for each specific case, preventing degradation of prediction accuracy while avoiding unnecessary complexity in cases where simple prediction suffices.
3Reliability
If bi-directional intra prediction is applied to all angular modes, then prediction quality is improved, but computational complexity increases
Solution Approach 1:
The patent applies local quality by treating different angular modes differently based on their specific characteristics. Instead of uniformly applying bi-directional intra prediction to all modes, the system selectively applies it only to modes where the delta angle equals the predefined value. This localized approach ensures high prediction quality is achieved only where necessary, while reducing computational complexity in cases where simpler prediction methods are sufficient.
Data Source
AI summary
Coded information of a current block and neighboring blocks of the current block is received, where the current block is predicted in an intra directional mode. The intra directional mode of the current block is determined to be associated with an angle that is one of smaller than 90 degrees and larger than 180 degrees. In response to the intra directional mode of the current block being associated with the angle, whether a delta angle associated with the current block is a pre-defined delta angle is determined. In response to the delta angle associated with the current block not being the pre-defined delta angle, a single direction intra prediction and not a bi-direction intra prediction is applied to the current block. A sample of the current block is reconstructed based on an adjacent reference sample on a reference line that is determined according to the single direction intra prediction.