VVC Decoder-Derived Intra Prediction with Selective Angular Modes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The computational complexity and performance of Decoder Side Intra Mode Derivation (DIMD) coding tool in video coding systems, particularly in VVC, are not optimally addressed, leading to inefficiencies in video decoding processes.
Innovation Solution
A method and apparatus for video coding that reduces computational complexity by determining a selected set of angular intra prediction candidate modes based on block size and neighboring block prediction modes, using statistics or histograms, and applying gradient filters to derive a final intra predictor, with optional signaling of delta angles to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all angular intra prediction modes are evaluated for DIMD, then prediction accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent segments the full set of angular intra prediction modes into multiple subsets based on block characteristics (size, shape, neighboring block modes). Instead of evaluating all modes, the decoder selectively evaluates only relevant subsets, reducing computational complexity while maintaining prediction accuracy for different block types
Solution Approach 2:
The patent applies partial action by evaluating only a subset of angular modes rather than all modes. The selection of which subset to evaluate depends on block characteristics, applying just enough computational effort to achieve good prediction accuracy without the excessive complexity of full mode evaluation
2Productivity
If DIMD is applied to all block types, then coding efficiency is improved, but processing time increases
Solution Approach 1:
The patent applies local quality by adapting the DIMD process to different block types locally. Small blocks use a simplified mode subset evaluation, while larger blocks use more comprehensive evaluation. This ensures coding efficiency is improved where needed without uniformly increasing processing time for all blocks
3Reliability
If the full set of angular intra prediction modes is used, then prediction performance is improved, but decoder complexity increases
Solution Approach 1:
The patent makes the decoder dynamic by adaptively selecting which angular mode subsets to evaluate based on real-time block characteristics (size, aspect ratio, neighboring block modes). This dynamic adaptation maintains high prediction performance when needed while reducing complexity for blocks where full evaluation is unnecessary
Data Source
AI summary
Methods and apparatus for video coding are disclosed. According to one method, a selected set of angular intra prediction candidate modes corresponding to a subset of an initial set of angular intra prediction modes is used to derive DIMD candidates. In another method, a delta angle between the final intra prediction mode and a DIMD derived mode is signalled or parsed. In yet another method, a DIMD candidate mode is determined by using a process including comparing gradient magnitudes of the gradient filtered results with a threshold.