Deblocking Filter Control for Affine Video Coding
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Solution Overview
Problem
Video coders face issues with over-smoothing of subblock boundaries when both pattern refined optical flow (PROF) and deblocking filter operations are applied, leading to loss of important features in video data, and this consumes processing resources.
Innovation Solution
Selective disabling of deblocking filter operations or modifying boundary strength calculations for subblock boundaries of affine coded coding blocks, based on the coding mode and enablement of PROF, to avoid over-smoothing and optimize processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If deblocking filter operations are applied to subblock boundaries of affine coded blocks, then blockiness artifacts are reduced, but over-smoothing occurs and important features are lost
Solution Approach 1:
The patent applies different deblocking filter strengths to different boundary types: strong filtering for inter-block boundaries to remove artifacts, but weak or no filtering for intra-block subblock boundaries to preserve features. This local differentiation resolves the contradiction by applying filtering only where needed.
Solution Approach 2:
The patent dynamically adjusts the boundary strength parameter based on the coding mode (affine vs. non-affine) and the specific boundary location. For affine coded blocks, the boundary strength is reduced or set to zero for subblock boundaries, while maintaining normal strength for other boundaries, making the filtering adaptive to content characteristics.
2Manufacturing precision
If deblocking filter operations are applied to all subblock boundaries, then boundary smoothness is improved, but processing resources are consumed
Solution Approach 1:
The patent extracts and removes the deblocking filter operation from specific subblock boundaries where it is not needed (intra-block boundaries of affine coded blocks). By taking out the filtering operation only from these specific locations rather than applying it universally, processing resources are conserved while maintaining boundary smoothness where required.
Solution Approach 2:
Instead of applying full deblocking filtering to all boundaries, the patent applies partial filtering only to necessary boundaries (inter-block boundaries and non-affine blocks). This partial action approach achieves sufficient boundary smoothness without the excessive processing cost of universal filtering.
3Manufacturing precision
If PROF and deblocking filter operations are both applied, then subblock boundaries are smoothed, but over-smoothing occurs and features are washed out
Solution Approach 1:
The patent applies preliminary anti-action by disabling or reducing the deblocking filter strength for subblock boundaries of affine coded blocks before the filter can cause over-smoothing. This preventive measure counteracts the potential harmful effect of combining PROF and deblocking filtering, preserving features while still allowing PROF to perform its motion refinement function.
Data Source
AI summary
An example device for decoding video data includes memory configured to store the video data and one or more processors implemented in circuitry and communicatively coupled to the memory. The one or more processors are configured to determine whether a coding mode for a current block of the video data is an affine mode. The one or more processors are also configured to determine whether pattern refined optical flow (PROF) is enabled in the sequence parameter set (SPS) for the current block. Based at least in part on the coding mode for the current block being the affine mode and PROF being enabled in the SPS for the current block, the one or more processors are configured to disable a deblocking filter for subblock boundaries of the current block and decode the current block with the deblocking filter disabled for the subblock boundaries of the current block.