Intra Prediction Mode Remapping for Wide-Angle Video Blocks
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Solution Overview
Problem
Existing video coding technologies face inefficiencies in intra prediction due to the limited number of directions and bit allocation for less likely prediction modes, leading to suboptimal compression ratios and increased bit usage.
Innovation Solution
The proposed method involves remapping intra prediction modes for sub-partitions of a coding block, using wide-angle modes based on aspect ratios and lookup tables to optimize bit allocation and improve compression efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional intra prediction modes with limited directions are used, then the coding structure remains simple, but the compression ratio is suboptimal and bit usage increases
Solution Approach 1:
The patent changes the parameter of prediction direction by introducing wide-angle prediction modes that extend beyond the traditional angular range. This allows the encoder to select from a broader set of prediction directions, improving compression efficiency for content with oblique edges while maintaining a manageable mode structure through systematic parameter expansion.
Solution Approach 2:
The patent segments the prediction mode selection process by dividing modes into categories (e.g., non-angular, angular, wide-angle) with different bit allocation strategies. This segmentation allows optimized bit usage for each category, allocating more bits to likely modes and fewer bits to less likely modes, thereby improving overall compression ratio without uniformly increasing complexity.
2Manufacturing precision
If more prediction directions are added to improve compression, then compression ratio improves, but bit allocation for less likely modes becomes inefficient
Solution Approach 1:
The patent introduces a remapping mechanism that transforms the relationship between mode indices and actual prediction directions. By dynamically remapping modes based on block characteristics (e.g., aspect ratio), the system optimizes bit allocation efficiency - commonly occurring directions receive more bits while rare directions receive fewer bits, reducing overall bit usage without sacrificing compression quality.
Solution Approach 2:
The patent implements dynamic mode remapping that adapts to the specific characteristics of each coding block. The remapping table is adjusted based on block aspect ratios and other parameters, allowing the bit allocation strategy to dynamically match the actual content characteristics, thereby preventing inefficient bit allocation for unlikely prediction modes.
3Productivity
If wide-angle prediction modes are introduced for non-square blocks, then compression efficiency improves, but the complexity of mode remapping increases
Solution Approach 1:
The patent applies local quality by introducing wide-angle prediction modes specifically for non-square blocks where they are most beneficial, rather than uniformly across all block types. The remapping complexity is localized to cases where aspect ratios indicate potential benefit, allowing coding efficiency improvements where needed while minimizing overall system complexity through selective application.
Solution Approach 2:
The patent uses parameter-based remapping tables that are pre-computed and stored, transforming the complex remapping logic into simple lookup operations. By parameterizing the remapping based on block characteristics like aspect ratio, the system achieves high coding efficiency through efficient table-driven implementation rather than complex real-time calculations.
Data Source
AI summary
A method for video decoding includes decoding prediction information that indicates a partition of the current block and indicates an index indicating a first intra prediction mode in a first set of intra prediction modes for a first partition of the current block. The method further includes, when the first partition has a non-square shape, remapping the first intra prediction mode to a second intra prediction mode based on an aspect ratio of the first partition. When the aspect ratio of the first partition is out of a specific range, a number of intra prediction modes in the first set of intra prediction modes that are replaced by wide-angle intra prediction modes is fixed to a pre-defined number. The method further includes decoding at least the first partition according to the first intra prediction mode or the second intra prediction mode.