Adaptive Loop Filter Parameter Selection for Video Decoding
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Solution Overview
Problem
Current video processing technologies, particularly in HEVC, face challenges in efficiently signaling adaptive loop filter settings for optimal video decoding, leading to suboptimal filtering of video pixels and potential artifacts.
Innovation Solution
The implementation of a method where a video decoder selects adaptive parameter sets (APS) for filtering blocks of pixels, choosing between multiple APSs or default filters based on specific criteria, and applies geometric transformations to filter coefficients for improved alignment and efficiency, allowing for adaptive loop filtering at the block level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple adaptive parameter sets (APS) are provided for filtering, then video quality and filtering adaptability are improved, but device complexity and processing overhead increase
Solution Approach 1:
The patent segments the filtering parameters into multiple adaptive parameter sets (APS), where each APS contains a subset of filter coefficients and parameters. The decoder can select from multiple APS based on block characteristics, enabling adaptive filtering without requiring all parameters to be processed simultaneously. This segmentation reduces the complexity of handling all filtering parameters at once while maintaining high adaptability.
Solution Approach 2:
The patent prepares multiple adaptive parameter sets (APS) in advance, with each APS containing pre-configured filter coefficients and parameters optimized for different block types and characteristics. During decoding, the appropriate pre-prepared APS is selected based on the current block's properties, eliminating the need for real-time parameter generation and reducing processing complexity while maintaining high filtering adaptability.
2Manufacturing precision
If adaptive parameter sets are selected and applied, then filtering precision and video quality are improved, but processing time and computational load increase
Solution Approach 1:
Multiple adaptive parameter sets (APS) with different filter coefficients and parameters are prepared in advance for various block types and characteristics. During decoding, the appropriate pre-prepared APS is selected based on the current block's properties, eliminating the need for real-time parameter generation and reducing processing time while maintaining high filtering precision.
Solution Approach 2:
The patent changes filtering parameters by selecting from multiple pre-configured adaptive parameter sets (APS) rather than computing parameters in real-time. Each APS contains optimized filter coefficients and parameters for specific block characteristics. This parameter selection approach maintains high filtering precision while significantly reducing computational load and processing time compared to real-time parameter optimization.
3Manufacturing precision
If geometric transformations are applied to filter coefficients, then filter alignment and filtering effectiveness are improved, but computational complexity increases
Solution Approach 1:
The patent applies geometric transformations (rotation, reflection, translation) to filter coefficients within the adaptive parameter sets to improve filter alignment with block characteristics. These transformations modify the parameters in pre-prepared APS rather than requiring complex real-time computations, achieving improved filter alignment while keeping processing complexity manageable through efficient transformation operations.
Data Source
AI summary
A method for signaling adaptive loop filter (ALF) settings is provided. A video decoder receives data from a bitstream for a block of pixels to be decoded as a current block of a current picture of a video. The video decoder parses whether to use adaptive parameter set (APS) for filtering the current block without determining whether to select a particular APS from a plurality of APSs. When the APS is used to filter the current block, the video decoder parses a first filter selection index for selecting a filter from a set of filters in the APS. When the APS is not used to filter the current block, the video decoder signals a second filter selection index for selecting a filter from a set of default fixed filters. The video decoder filters the current block based on the selected filter. The video decoder outputs the filtered current block.