Video Coding With Clipped CCALF–ALF Chroma Coefficients
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Solution Overview
Problem
Existing video coding technologies face challenges in improving coding efficiency, enhancing image quality, and reducing circuit scale and processing resources, particularly in the context of cross component adaptive loop filtering processes.
Innovation Solution
Implementing a cross component adaptive loop filtering (CCALF) process that clips coefficient values for both luma and chroma components, followed by adding them to enhance image quality and efficiency, and incorporating adaptive loop filtering (ALF) processes to optimize encoding and decoding operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CCALF process is applied to improve chroma component quality, then image quality is improved, but processing complexity increases
Solution Approach 1:
The patent segments the CCALF processing into distinct stages: luma coefficient generation, clipping operation, chroma coefficient generation, and final combination. This segmentation allows each stage to be optimized independently, reducing overall processing complexity while maintaining image quality improvements.
Solution Approach 2:
The patent introduces clipping as a parameter change operation that constrains coefficient values to specific ranges. This simplifies subsequent processing by ensuring coefficients remain within valid bounds, reducing the complexity of downstream operations while preserving quality enhancement.
2Productivity
If multiple filtering processes (CCALF and ALF) are applied to enhance coding efficiency, then coding efficiency is improved, but processing resources increase
Solution Approach 1:
The patent merges CCALF and ALF processes by having both luma and chroma components contribute to a unified chroma reconstruction. This consolidation allows shared processing resources and reduces redundant operations compared to completely separate filtering processes.
Solution Approach 2:
The patent applies partial action by selectively processing only the chroma component through the combined CCALF-ALF process, while luma is processed separately. This targeted approach reduces overall processing resources compared to applying full filtering to all components.
3Device complexity
If coefficient clipping is applied to simplify processing, then processing complexity is reduced, but precision is lost
Solution Approach 1:
The patent carefully designs the clipping operation to change coefficients only within specific ranges, preserving precision for significant values while simplifying extreme values. This selective parameter change maintains necessary precision without excessive complexity.
Solution Approach 2:
The patent applies different clipping thresholds and strategies to different coefficient positions and components (luma vs. chroma), maintaining local quality where precision is most needed while simplifying processing where it is less critical.
Data Source
AI summary
An encoder includes circuitry and memory. The circuitry, in operation, generates a first coefficient value by applying a CCALF (cross component adaptive loop filtering) process to a first reconstructed image sample of a luma component. The circuitry generates a second coefficient value by applying an ALF (adaptive loop filtering) process to a second reconstructed image sample of a chroma component. The circuitry generates a third coefficient value by adding the first coefficient value to the second coefficient value, and encodes a third reconstructed image sample of the chroma component using the third coefficient value. In the CCALF process, in response to a coordinate of the second reconstructed image sample being (x, y), coordinates of the first reconstructed image samples are (2x, 2y−1), (2x−1, 2y), (2x, 2y), (2x+1, 2y), (2x−1, 2y+1), (2x, 2y+1), (2x+1, 2y+1), and (2x, 2y+2).