CCALF Video Coding Across Virtual Boundaries
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Solution Overview
Problem
Existing video coding technologies face challenges in improving coding efficiency, enhancing image quality, and reducing circuit scale, particularly in the context of cross component adaptive loop filtering processes.
Innovation Solution
Implementing a cross component adaptive loop filtering (CCALF) process that generates coefficient values by duplicating reconstructed samples across virtual boundaries, combining luma and chroma components, and applying adaptive loop filtering to enhance image quality and coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a first reconstructed image sample located outside a virtual boundary is duplicated from an adjacent reconstructed sample inside the boundary to generate the first reconstructed image sample, then the CCALF process can be applied to enhance image quality, but the processing complexity and circuit scale increase
Solution Approach 1:
The patent applies the copying principle by duplicating reconstructed sample values from inside the virtual boundary to outside the boundary. This allows the CCALF process to access samples that would otherwise be unavailable, enabling filter coefficient generation for chroma components at boundary locations without requiring additional physical sensors or complex boundary handling logic. The copying operation is implemented through simple memory operations rather than complex circuitry.
Solution Approach 2:
The patent merges the luma component filtering process with the chroma component filtering process by applying CCALF. Instead of treating luma and chroma filtering separately, the invention combines them into a unified cross-component adaptive loop filtering process that generates coefficients from luma samples and applies them to chroma samples, reducing the need for separate filtering circuits and lowering overall device complexity.
2Productivity
If a CCALF process is applied to generate filter coefficients by combining luma and chroma components, then coding efficiency is improved, but the processing resources required increase
Solution Approach 1:
The patent applies self-service by using the luma component samples themselves to generate the filter coefficients that will be applied to the chroma component. The luma samples serve dual purposes: as the primary image data and as the source for generating filtering coefficients. This eliminates the need for separate coefficient generation circuits or additional reference samples, reducing processing resource requirements while maintaining coding efficiency.
3Manufacturing precision
If filter coefficients are generated by applying CCALF to reconstructed samples, then image quality is enhanced, but the processing time and computational load increase
Solution Approach 1:
The patent applies preliminary action by generating and storing the filtered chroma samples during the decoding process itself, before final image output or further processing. The CCALF filtering is performed as part of the reconstruction pipeline, so that when the filtered samples are needed for display or further processing, they are already available, eliminating the need for separate post-processing filtering steps and reducing overall processing time.
Data Source
AI summary
An encoder includes circuitry and memory coupled to the circuitry. The circuitry, in response to a first reconstructed image sample being located outside a virtual boundary, duplicates a reconstructed sample located inside and adjacent to the virtual boundary to generate the first reconstructed image sample. The circuitry generates a first coefficient value by applying a CCALF (cross component adaptive loop filtering) process to the 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.