Secondary Transform Selection for Matrix-Based Intra Prediction
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Solution Overview
Problem
Conventional intra prediction modes in video coding lack efficient secondary transforms for matrix-based prediction modes, leading to high memory requirements and increased bit stream costs.
Innovation Solution
Select a subset of secondary transforms from a set that includes both matrix-based and non-matrix-based intra prediction modes, allowing for reduced memory capacity and increased coding efficiency by associating specific transforms with matrix-based modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate secondary transform is defined for each matrix-based intra prediction mode, then prediction accuracy is improved, but memory requirements increase
Solution Approach 1:
The patent applies universality by enabling a single secondary transform to serve multiple matrix-based intra prediction modes. The secondary transform is selected based on the intra prediction mode used, allowing one transform definition to handle multiple prediction modes rather than requiring separate transforms for each mode, thus reducing memory requirements while maintaining prediction accuracy.
2Measurement precision
If a separate secondary transform is defined for each matrix-based intra prediction mode, then prediction accuracy is improved, but bit stream cost increases
Solution Approach 1:
The patent reduces bit stream cost by using a universal secondary transform that can be applied to multiple matrix-based intra prediction modes. Instead of signaling separate transforms for each mode, the system signals a single secondary transform index that corresponds to the appropriate transform for the given prediction mode, thereby reducing the number of bits required in the bit stream while maintaining prediction accuracy.
3Productivity
If conventional intra prediction modes use non-separable secondary transform, then coding efficiency is improved, but adaptability to matrix-based modes is reduced
Solution Approach 1:
The patent applies dynamics by making the secondary transform selection adaptive based on the intra prediction mode. The system dynamically selects which secondary transform to apply depending on whether the current block uses a matrix-based intra prediction mode or a conventional mode, allowing the coding system to adapt its behavior based on the specific prediction mode used, thereby maintaining coding efficiency across different mode types.
Data Source
AI summary
An apparatus configured to select a predetermined intra prediction mode out of a plurality of intra-prediction modes which includes a first set of intra-prediction modes and a second set of matrix-based intra-prediction modes. The apparatus is configured to select a subset of one or more secondary transforms dependent on the predetermined intra prediction mode so that the subset is nonempty in case of the predetermined intra prediction mode being contained in the first set of intra-prediction modes or in the second set of matrix-based intra-prediction modes. The apparatus is configured to derive a transformed version of a prediction residual for a predetermined block, which is related to a spatial domain version of the prediction residual of the predetermined block via a transform defined by a concatenation of a primary transform and a predetermined secondary transform out of the subset of secondary transforms.