Intra-prediction Modes for Non-Square Video Blocks
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Solution Overview
Problem
Current video coding standards, such as ITU-T H.265/HEVC, face challenges in achieving optimal coding efficiency and reducing computational complexity, particularly in directional intra-prediction for non-square video coding blocks, where the existing set of directional modes does not adequately account for block size and aspect ratio, leading to inefficiencies and increased signaling overhead.
Innovation Solution
An apparatus and method that dynamically adjust the number of directional intra-prediction modes based on the size and aspect ratio of non-square video coding blocks, by distributing modes across directional ranges and using a look-up table to determine the optimal number of modes for each block side, thereby improving coding efficiency and reducing redundant modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed set of directional intra-prediction modes is used for all block sizes, then the implementation is simple, but coding efficiency deteriorates for non-square blocks
Solution Approach 1:
The patent applies dynamics by making the number of directional intra-prediction modes variable rather than fixed. The encoder dynamically selects the number of modes (e.g., 35, 65, or 131 modes) based on the block size and aspect ratio, allowing the prediction system to adapt to different block geometries and improve coding efficiency for non-square blocks while maintaining implementation flexibility.
Solution Approach 2:
The patent applies local quality by using different numbers of directional modes for different blocks based on their specific characteristics. Each block can have a tailored set of prediction modes selected according to its size and aspect ratio, ensuring that each local region (block) uses the most appropriate number of modes for its geometry rather than a uniform approach.
2Productivity
If the number of directional intra-prediction modes is increased to improve prediction accuracy, then coding efficiency improves, but computational complexity increases
Solution Approach 1:
The patent applies partial or excessive action by selectively using a variable number of directional modes (ranging from 35 to 131) based on block characteristics. Instead of always using the maximum number of modes, the system uses only the necessary number of modes for each specific block, achieving sufficient prediction accuracy while avoiding unnecessary computational complexity for blocks that don't require extensive angular coverage.
Solution Approach 2:
The patent applies parameter changes by varying the number of directional modes as a controllable parameter based on block size and aspect ratio. This parameter adjustment allows the system to optimize the trade-off between coding efficiency and computational complexity by selecting appropriate mode counts (35, 65, or 131) according to the specific encoding scenario.
3Measurement precision
If more directional modes are used for all blocks, then prediction accuracy improves, but signaling overhead increases
Solution Approach 1:
The patent applies local quality by signaling different numbers of directional modes for different blocks based on their specific needs. The mode selection and signaling are localized to each block's characteristics (size and aspect ratio), ensuring that only the necessary prediction modes are signaled and used for each block rather than uniformly signaling all modes for every block.
Solution Approach 2:
The patent applies partial or excessive action by signaling only the necessary subset of directional modes for each block rather than always signaling the complete set. This selective signaling approach reduces the average signaling overhead while maintaining prediction accuracy where needed by using partial mode sets for blocks that don't require full angular coverage.
Data Source
AI summary
A device and method for intra-predicting a rectangular and non-square video coding block, the device including an intra-prediction apparatus configured for intra-predicting a rectangular and non-square video coding block according to a set of directional intra-prediction modes distributed over a set of directional ranges, where the intra-prediction apparatus being configured for configured for intra-predicting the rectangular and non-square video coding block includes the intra-prediction apparatus being configured to select a directional range from the set of directional ranges, and determine a number of directional intra-prediction modes of the selected directional range according to a size of a block.