Chroma Block ISP Prediction for Lower Residual Coding Overhead
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Solution Overview
Problem
Existing video compression techniques face inefficiencies in encoding chroma signals due to the lack of application of Intra Sub-Partitions (ISP) mode, which increases overhead and does not effectively handle various chroma formats, leading to increased data energy in residual signals, especially for rectangular blocks.
Innovation Solution
Adaptive application of sub-block split methods, transmission information, and transform methods for intra prediction on chroma signals using the ISP mode, including decoding chroma format, ISP enabled flags, and tree types from a bitstream to sub-split chroma blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Intra Sub-Partitions (ISP) mode is applied to chroma signals, then coding efficiency is improved and residual signal energy is reduced, but overhead for transmitting prediction mode information increases
Solution Approach 1:
The chroma block is divided into multiple sub-blocks (e.g., 2x2 sub-blocks) along the vertical direction, allowing different prediction modes to be applied to different sub-blocks. This segmentation enables more precise local prediction while managing overhead through selective application of ISP mode based on block characteristics
Solution Approach 2:
Different prediction modes (e.g., vertical, horizontal, diagonal) are applied to different sub-blocks based on local characteristics. This allows each sub-block to use the most appropriate prediction mode for its specific content, improving overall coding efficiency while maintaining controlled overhead through context-based mode selection
2Measurement precision
If block sub-splitting is performed to reduce residual signal energy, then prediction accuracy is improved, but overhead for transmitting intra prediction mode for each sub-split block increases
Solution Approach 1:
The chroma block is segmented into multiple sub-blocks to improve prediction accuracy for rectangular blocks. By dividing the block into smaller regions, the distance between reference pixels and target pixels is reduced, improving prediction accuracy while the segmentation structure itself helps manage overhead
Solution Approach 2:
The prediction mode selection is made dynamically based on block characteristics (e.g., aspect ratio, size, content complexity). For rectangular chroma blocks where sub-splitting is beneficial, ISP mode is applied; for other blocks, conventional single-mode prediction is used, creating a dynamic adaptation strategy that balances accuracy and overhead
3Adaptability or versatility
If ISP mode is applied to chroma signals, then various chroma formats can be handled more effectively, but device complexity increases due to additional processing requirements
Solution Approach 1:
The ISP mode implementation is designed to be universal across different chroma formats (4:2:0, 4:2:2, 4:4:4). The same sub-blocking and prediction mode selection mechanism works for all formats, with the processing adapted to the specific format requirements, providing multi-format support without requiring separate processing paths for each format
Solution Approach 2:
The implementation adapts processing parameters (such as sub-block size, prediction mode candidates, and transform types) based on the chroma format being processed. This parameter adaptation allows effective handling of various formats while managing complexity through conditional logic rather than separate processing architectures
Data Source
AI summary
A method and an apparatus for video coding using intra sub-block prediction of a chroma block are disclosed. The video coding method and the apparatus adaptively apply a sub-block split method, transmission information, and a transform method in performing intra prediction on chroma signals of a current block using an intra sub-partitions (ISP) mode.