Adaptive Intra-Mode Coding by Block Location to Remove Boundary Redundancy
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Solution Overview
Problem
Existing video coding techniques face inefficiencies in encoding and decoding intra-prediction modes due to the use of padding for blocks at image boundaries, leading to redundant encoding and decreased coding efficiency and video quality.
Innovation Solution
Adaptive encoding and decoding of intra-prediction modes based on the position of the current block, generating a Most Probable Mode (MPM) list by removing redundant prediction modes and determining a representative mode to reorganize the MPM list.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If padding is used to generate reference pixel values for empty positions at image boundaries, then intra prediction can be performed for all blocks, but encoding efficiency decreases and video quality is reduced
Solution Approach 1:
The patent applies different intra prediction mode encoding strategies based on block position. Boundary blocks (top row, left column, or both) use a simplified encoding method that skips redundant mode listing, while non-boundary blocks use the standard MPM-based encoding. This local differentiation eliminates unnecessary encoding operations for boundary blocks, improving overall encoding efficiency without compromising prediction reliability.
2Measurement precision
If all intra-prediction modes are encoded separately for each block, then prediction accuracy is maintained, but coding efficiency is reduced due to redundancy
Solution Approach 1:
The patent changes the encoding parameters based on block position. For boundary blocks, the intra prediction mode is directly set to a predetermined mode (e.g., mode 0 or mode 1) without encoding all possible modes. For non-boundary blocks, the standard MPM encoding with multiple candidates is used. This parameter adaptation reduces the number of encoded modes for boundary blocks, improving coding efficiency while maintaining adequate prediction accuracy.
Solution Approach 2:
Instead of encoding all 67 intra prediction modes for every block, the patent applies partial encoding by only listing relevant modes for boundary blocks. The excessive action of encoding all modes is reduced to only necessary modes, achieving sufficient prediction accuracy with significantly reduced coding complexity and improved efficiency.
3Stability of the object's composition
If the same predictor is generated by using different prediction modes at image boundaries, then prediction consistency is achieved, but encoding redundancy increases
Solution Approach 1:
The patent extracts and removes redundant prediction modes from the encoding process for boundary blocks. By identifying that certain modes produce the same predictor as the predetermined mode at boundaries, the patent takes out these redundant modes from the MPM list, keeping only the necessary predetermined mode. This eliminates encoding redundancy while maintaining prediction consistency.
Solution Approach 2:
The patent discards redundant prediction modes for boundary blocks where they produce identical predictors to the predetermined mode. Instead of encoding all modes and then filtering, the patent proactively discards only the necessary modes from the start, recovering the essential prediction functionality while eliminating unnecessary encoding information.
Data Source
AI summary
A method and an apparatus are disclosed for adaptive coding of intra mode based on block position. In the disclosed embodiments, a video decoding device determines a type of the current block based on its position and generates an MPM list including MPM candidates. The video decoding device determines, among the MPM candidates and based on the type of the current block, redundant prediction modes. The video decoding device determines a representative mode among the redundant prediction modes and reorganizes the MPM list by removing redundant prediction modes other than the representative mode. The video decoding device decodes from a bitstream an MPM index of the current block and determines from a reorganized MPM list an intra-prediction mode of the current block by using the MPM index.