Video Filter Region Alignment for Memory Reduction
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Solution Overview
Problem
Conventional video coding systems require multiple filter sets for each filtering region, leading to increased memory requirements and complexity in the decoding pipeline due to delayed filtering at region boundaries, where necessary samples are not yet available.
Innovation Solution
The proposed solution aligns filter parameter setting regions with filtering processing windows by shifting their boundaries relative to Largest Coding Units (LCUs), allowing complete processing within each region before moving to the next, thereby reducing the need for multiple filter sets and simplifying the pipeline.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If filter parameter setting regions are aligned with LCU boundaries, then processing can be performed in parallel across regions, but multiple filter parameter sets must be stored in memory for delayed filtering at region boundaries
Solution Approach 1:
The patent inverts the conventional approach by shifting filter parameter setting region boundaries away from LCU boundaries. Instead of aligning filter regions with LCUs (conventional approach), the patent defines filter regions that are offset from LCU boundaries, allowing filtering to be completed within each filter region before transitioning to the next region. This inversion eliminates the need to store multiple filter parameter sets in memory for delayed filtering operations.
Solution Approach 2:
The patent applies preliminary action by ensuring that all necessary filtering operations are completed within each filter parameter setting region before moving to the next region. By carefully defining filter region boundaries and shifting them relative to LCU boundaries, the patent enables complete filtering processing to be performed in advance within each region, eliminating the need for delayed filtering and reducing memory requirements for storing multiple filter parameter sets.
2Ease of manufacture
If filter parameter setting regions are shifted relative to LCU boundaries, then complete processing can be performed within each region, but the alignment between filtering regions and coding units becomes misaligned
Solution Approach 1:
The patent deliberately misaligns filter parameter setting regions with LCU boundaries to simplify the filtering pipeline. By shifting filter region boundaries away from LCU boundaries, the patent enables complete filtering processing to be performed within each filter region without requiring delayed filtering operations. This intentional misalignment simplifies the hardware implementation by eliminating the need to store and manage multiple filter parameter sets for different regions.
3Adaptability or versatility
If multiple filter sets are maintained for different regions, then filtering can be performed across LCU boundaries, but device complexity increases due to memory management requirements
Solution Approach 1:
The patent extracts the delayed filtering operation from the conventional pipeline and eliminates it entirely by shifting filter parameter setting region boundaries. Instead of maintaining multiple filter sets in memory for delayed filtering across LCU boundaries, the patent redefines filter regions so that complete filtering can be performed within each region. This extraction and elimination of the delayed filtering step reduces device complexity by removing memory management requirements for multiple filter parameter sets.
Data Source
AI summary
The present invention relates to a simplified pipeline for Sample Adaptive Offset (SAO) and Adaptive Loop Filtering (ALF) in the in-loop decoding of a video encoder and a video decoder. According to the present invention, filter parameter setting regions and filtering processing windows are aligned, to reduce the required amount of memory for parameter sets necessary for delayed filtering. This is preferably achieved by a displacement of the filter parameter setting regions with respect to LCU boundaries in at least one (preferably: vertical) or both vertical and horizontal directions.