Cross-Component Adaptive Loop Filter for Chroma Refinement
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Solution Overview
Problem
Current video coding technologies lack flexibility in cross-component adaptive loop filtering (CC-ALF), leading to inefficient refinement of chroma samples using luma sample values, and there is a need to improve the signaling and application of CC-ALF in video encoding and decoding processes.
Innovation Solution
The proposed solution involves extending CC-ALF to allow corrections for samples in one component by filtering samples in another component, excluding cases where the first component is Y, and using multiple CC-ALF filters or adaptation parameter sets (APS) for different video regions or samples, with signaling mechanisms to indicate the usage and parameters of CC-ALF.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single ALF adaptation parameter set (APS) is used for CC-ALF, then the device complexity is reduced, but the adaptability to different video regions and components is limited
Solution Approach 1:
The patent divides the video processing into multiple ALF APS, each dedicated to specific components (luma, chroma) or regions. This segmentation allows independent optimization for different components without requiring a single complex APS to handle all cases, thereby improving adaptability while keeping each individual APS relatively simple.
Solution Approach 2:
The patent creates multiple ALF APS that can be universally applied to different components and regions. Each APS is designed to be reusable across multiple contexts (different video blocks, different components), allowing the system to achieve high adaptability through a set of standardized, multi-functional parameter sets rather than requiring custom parameters for every scenario.
2Manufacturing precision
If multiple CC-ALF filters are applied to different samples, then the manufacturing precision of chroma sample refinement is improved, but the processing time increases
Solution Approach 1:
The patent applies different CC-ALF filters to different video regions or sample types based on their specific characteristics. Instead of using a single filter for all samples, the system selects appropriate filters locally for each region or component type, improving refinement precision while avoiding the unnecessary application of multiple filters to all samples, thus balancing quality with processing efficiency.
3Manufacturing precision
If CC-ALF is applied to all chroma samples, then the quality of chroma refinement is improved, but the bitstream overhead increases
Solution Approach 1:
The patent applies CC-ALF selectively to specific chroma samples or regions rather than uniformly to all chroma samples. By identifying and applying the filter only where it provides the most benefit (partial action), the system achieves significant chroma refinement quality improvement while minimizing the bitstream overhead associated with signaling and processing, avoiding excessive application in regions where the filter would provide minimal benefit.
Data Source
AI summary
A method of video processing includes making a determination for a conversion between a video region of a video and a bitstream representation of the video to use a cross-component adaptive loop filtering (CC-ALF) tool for refining chroma samples values using luma sample values; and performing the conversion based on the determination, wherein the refining includes correcting the chroma sample values using a final refinement that is a further refinement of a first refinement value determined by selectively filtering the luma sample values.