Angular Intra Prediction With Delta-Angle Mode Selection
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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 video 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, and bi-directional intra prediction when the delta angle matches specific values (e.g., 0, 2, or −2 degrees) for directional modes within certain angle ranges, using a predefined delta angle mapping table to determine the appropriate prediction mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bi-directional intra prediction is applied to directional modes with angles between 90 and 180 degrees, then prediction accuracy may be improved, but computational complexity increases
Solution Approach 1:
The patent changes the prediction mode parameter based on the delta angle value. When the delta angle matches a predefined value (0, 2, or -2 degrees), bi-directional intra prediction is applied to improve accuracy. For other delta angle values, single direction intra prediction is used to reduce computational complexity. This conditional parameter change resolves the contradiction by adapting the prediction method to the specific angular characteristics of the current block.
2Device complexity
If single direction intra prediction is applied to all directional modes, then computational complexity is reduced, but prediction accuracy deteriorates for certain angle ranges
Solution Approach 1:
The patent applies different prediction qualities to different local cases based on the delta angle. For directional modes with angles between 90 and 180 degrees where the delta angle matches predefined values, bi-directional prediction (higher quality) is applied. For other cases, single direction prediction (lower complexity) is used. This local differentiation resolves the contradiction by optimizing the balance between accuracy and complexity for each specific angular case.
3Measurement precision
If bi-directional intra prediction is applied to all blocks, then prediction accuracy is improved, but encoding/decoding time increases
Solution Approach 1:
Instead of applying bi-directional intra prediction to all blocks (excessive action), the patent applies it only partially to blocks where the delta angle matches predefined values (0, 2, or -2 degrees). This partial application maintains prediction accuracy where needed while significantly reducing the overall encoding/decoding time by avoiding unnecessary complex computations for other blocks.
4Productivity
If single direction intra prediction is applied to all blocks, then processing speed is improved, but prediction accuracy deteriorates for blocks with specific angular characteristics
Solution Approach 1:
The patent makes the prediction method dynamic by conditioning it on the delta angle value. The system automatically switches between single direction and bi-directional intra prediction based on whether the delta angle matches predefined values. This dynamic adaptation allows the system to maintain high processing speed overall while selectively improving prediction accuracy for blocks with specific angular characteristics where bi-directional prediction is beneficial.
Data Source
AI summary
A non-transitory computer-readable medium storing a video media bitstream that is encoded by an encoding method. In the encoding method, when an intra directional mode of a current block is associated with an angle that is one of smaller than 90 degrees and larger than 180 degrees, whether a delta angle associated with the current block is a pre-defined delta angle is determined. When the delta angle associated with the current block is not the pre-defined delta angle, a single direction intra prediction is applied to the current block. A sample of the current block is encoded in the video media bitstream based on an adjacent reference sample on a reference line that is determined according to the applied single direction intra prediction.