MIP Chroma Prediction in 4:4:4 Single-Tree Video Decoding
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Solution Overview
Problem
Current video coding technologies do not support matrix-based intra prediction (MIP) for all color components, particularly in the 4:4:4-chroma format, leading to inefficiencies in bit stream and coding complexity.
Innovation Solution
Implementing a block-based decoder/encoder that uses the same MIP mode for co-located intra-predicted blocks of different color components, equally sampled and partitioned, to enhance correlation and reduce bit stream and coding complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MIP mode is applied to chroma blocks in 4:2:0 or dual-tree cases, then prediction accuracy improves, but block shape compatibility deteriorates because co-located luma blocks may have different shapes than chroma blocks
Solution Approach 1:
The patent applies different MIP mode handling strategies based on the specific block configuration. For 4:4:4 chroma format with single tree, the chroma block uses the same MIP mode as the co-located luma block. For 4:2:0 or dual-tree cases where block shapes differ, the chroma block falls back to planar mode. This local adaptation resolves the contradiction by optimizing for prediction accuracy when block shapes match while maintaining compatibility when they don't.
2Measurement precision
If separate MIP modes are selected for each color component, then prediction precision improves, but device complexity increases due to additional mode selection and signaling
Solution Approach 1:
The patent merges the MIP mode selection for chroma blocks with the luma block's MIP mode in 4:4:4 chroma format with single tree. Instead of independently selecting MIP modes for luma and chroma blocks, the chroma block inherits the luma block's MIP mode index. This merging reduces the search space and mode selection complexity while maintaining prediction precision through correlation exploitation.
3Productivity
If MIP mode is applied to all color components, then coding efficiency improves, but bit stream cost increases due to additional signaling requirements
Solution Approach 1:
The patent copies the MIP mode index from the co-located luma block to the chroma block in 4:4:4 chroma format with single tree. This copying approach allows MIP mode application to all color components without additional signaling overhead, as the chroma block reuses the luma block's mode index. The bit stream cost is reduced while maintaining coding efficiency through correlated prediction.
Data Source
AI summary
A video decoder includes one or more processors that are configured to: determine that a picture is in a 4:4:4 color sampling format, determine, based at least in part on an index signaled in a data stream, a matrix-based intra prediction (MIP) mode, decode a luma block of the picture using the MIP mode, determine, for a chroma block of the picture, whether a coding tree of the chroma block is a single tree, select an intra prediction mode for decoding the chroma block, and decode the chroma block using the selected intra prediction mode. The selected intra prediction mode is the MIP mode in response to the coding tree of the chroma block being the single tree, and the selected intra prediction mode is a planar intra prediction mode in response to the coding tree of the chroma block not being the single tree.