Adaptive Loop Filter Chroma Selection for Lower Memory Use
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing adaptive loop filters (ALF) in video coding, such as linear and non-linear extensions, lack flexibility and efficiency, leading to increased memory requirements and suboptimal coding performance due to the use of multiple Adaptation Parameter Sets (APS) in Versatile Video Coding (VVC).
Innovation Solution
Implementing a method to control the adaptive loop filter by signaling alternative chroma filters with a limited number of filter coefficients and indices, using truncated unary binarization, and imposing limits on the maximum number of filters to manage memory usage and enhance coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple Adaptation_parameter Sets (APS) are used in VVC to improve filtering quality, then filtering quality is improved, but memory requirements increase and device complexity increases
Solution Approach 1:
The patent merges multiple APS into a single unified APS structure. Instead of maintaining separate adaptation parameter sets for different filter configurations, the invention combines them into one consolidated APS that manages all filter coefficients and parameters, thereby reducing memory requirements and device complexity while preserving filtering quality.
Solution Approach 2:
The unified APS structure serves multiple functions simultaneously: it stores coefficients for both linear and non-linear filters, manages alternative chroma filters, and provides adaptive filtering capabilities across different video content types. This multi-functional design eliminates the need for multiple specialized APS, reducing overall system complexity.
2Productivity
If multiple alternative chroma filters are provided to improve coding efficiency, then coding efficiency is improved, but the number of filters increases leading to increased complexity
Solution Approach 1:
The patent implements dynamic filter selection where the number and type of alternative chroma filters are adaptively determined based on video content characteristics and coding conditions. Rather than providing a fixed large set of filters, the system dynamically selects and activates only the necessary filters for each coding scenario, improving coding efficiency while controlling complexity.
Solution Approach 2:
The invention changes the parameter of filter quantity from a static large number to a dynamically adjusted value. By modifying the number of active filters based on content requirements and coding efficiency needs, the system achieves optimal performance without maintaining a permanently large filter set, thus balancing coding efficiency with device complexity.
3Reliability
If the maximum number of filters is increased to improve filtering performance, then filtering performance is improved, but memory usage increases
Solution Approach 1:
The patent applies local quality by providing different numbers and types of filters for different chroma components and different regions of the video signal. Instead of uniformly increasing the filter count across all components, the system selectively applies enhanced filtering only where needed, improving overall filtering performance while minimizing memory usage by avoiding redundant filter storage.
Data Source
AI summary
A method of controlling an Adaptive Loop Filter comprises obtaining for a slice containing one or more coding tree blocks, data indicating a number of available alternative chroma filters, obtaining for a coding tree block in the slice, an alternative filter index identifying one of the available alternative chroma filters, and selecting the alternative chroma filter identified by the index to filter chroma image data in the coding tree block.