Template-Based Intra Mode Derivation with Wide-Angle Prediction
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Solution Overview
Problem
Existing video coding systems face challenges in efficiently deriving intra prediction modes, particularly for non-square blocks, leading to suboptimal compression and decoding performance.
Innovation Solution
The implementation of template-based intra mode derivation (TIMD) with wide-angle intra prediction (WAIP) to generate a most probable mode (MPM) list, allowing for the exclusion of certain modes and using computed weights based on sum of absolute transform differences (SATDs) to optimize prediction for current blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If template-based intra mode derivation (TIMD) with wide-angle intra prediction (WAIP) is implemented to improve prediction accuracy, then compression performance is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-defining a Most Probable Mode (MPM) list and a test list of intra prediction modes before actual prediction. The test list is determined in advance from the MPM list, and certain modes are pre-excluded based on WAIP substitution rules. This preliminary preparation reduces the number of modes that need to be evaluated during actual prediction, thereby improving accuracy while managing computational complexity.
Solution Approach 2:
The patent implements partial action by not testing all possible intra prediction modes. Instead, it selectively tests only those modes in the test list that are not excluded by WAIP substitution rules. The first intra prediction mode is excluded from testing when WAIP substitution applies, while the second mode is included. This selective approach achieves good prediction accuracy without the computational burden of evaluating all modes.
2Productivity
If multiple intra prediction modes are tested and weighted combinations are computed to improve prediction quality, then compression efficiency is improved, but processing time increases
Solution Approach 1:
The patent uses preliminary action by pre-computing weights for multiple intra prediction modes based on Sum of Absolute Transform Differences (SATD) before generating the final prediction. The weights are determined in advance for the tested modes, allowing the final prediction to be generated by combining results from the second intra prediction mode and the first intra prediction mode using these pre-computed weights. This reduces processing time during actual compression while maintaining compression efficiency.
3Device complexity
If wide-angle intra prediction substitution is applied to exclude certain modes from testing, then computational complexity is reduced, but prediction accuracy may deteriorate
Solution Approach 1:
The patent applies parameter changes by modifying the test list based on the current block's shape parameters. When the current block is associated with a first shape (rectangular or square) and the intra prediction mode is associated with a second shape (square or rectangular) where adjacent sides differ in length, WAIP substitution excludes the first mode from testing. This parameter-based exclusion reduces computational complexity while the patent compensates by including the second intra prediction mode and using weighted combinations to maintain prediction accuracy.
Data Source
AI summary
Systems, methods, and instrumentalities are disclosed for performing video coding to derive intra prediction modes for predicting a current block using TIMD with wide-angle intra prediction (WAIP). A most probable mode (MPM) list associated with a current block may be obtained. A test list of intra prediction modes may be determined from the MPM list. A first intra prediction mode may be tested, and the first intra prediction mode may be excluded from the test list or disallowed to be tested due to WAIP substitution. A prediction for the current block may be generated based on the tested intra prediction mode. The current block may be decoded using the prediction.