Block-Based Adaptive Loop Filter Design for Video Coding
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Solution Overview
Problem
Existing video coding technologies face inefficiencies in adapting filtering techniques to local video data characteristics, leading to suboptimal coding efficiency and picture quality.
Innovation Solution
A method where a video encoder and decoder determine sets of adaptive loop filters on a per-block basis, allowing the selection of filters tailored to the local characteristics of the video data, improving coding efficiency and picture quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single set of adaptive loop filters is used for the entire picture, then device complexity and signaling overhead are reduced, but coding efficiency and picture quality deteriorate due to inability to adapt to local characteristics
Solution Approach 1:
The picture is divided into multiple blocks, and each block can have its own set of adaptive loop filters selected independently. This segmentation allows the filtering process to adapt to local characteristics of different regions while maintaining manageable complexity through block-level independence.
Solution Approach 2:
Different sets of adaptive loop filters are applied to different blocks based on their local characteristics. Each block's filter selection is tailored to its specific content requirements, enabling localized optimization of picture quality and coding efficiency without requiring uniform filtering across the entire picture.
2Productivity
If multiple sets of adaptive loop filters are selected per block, then coding efficiency and picture quality improve through better local adaptation, but signaling overhead and processing complexity increase
Solution Approach 1:
Multiple sets of candidate adaptive loop filters are prepared in advance for each block. The encoder selects the most appropriate set from these pre-prepared candidates based on local characteristics, and this selection is signaled to the decoder. This preliminary preparation enables efficient coding while controlling signaling overhead through selective transmission of only necessary selection information.
3Reliability
If adaptive loop filtering is applied to all blocks, then picture quality improves through consistent filtering, but processing time and computational complexity increase
Solution Approach 1:
Adaptive loop filtering is applied selectively to blocks where it provides the most benefit, rather than uniformly to all blocks. The encoder evaluates local characteristics and applies filtering only where needed, achieving good picture quality in critical regions while reducing overall processing time and computational complexity through targeted application.
Data Source
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AI summary
A video encoder and video decoder may determine a set of adaptive loop filters, from among a plurality of sets of adaptive loop filters, on a per-block basis. Each set of adaptive loop filters may include filters from a previous picture, filters signaled for the current picture, and/or pre-trained filter. By varying the set of adaptive loop filters on a per-block basis, the adaptive loop filters available for each block of video data may be more adapted to local statistics of the video data.