In-Loop Filter Constraints for 360-Degree Video Virtual Boundaries

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Solution Overview

Problem

The application of in-loop filters to virtual boundaries in 360-degree video encoding and decoding methods can lead to performance deterioration due to frame packing, particularly in omnidirectional video, where discontinuous boundaries cause subjective and objective quality issues.

Innovation Solution

A method is introduced to signal virtual boundary information and constrain the operation of the in-loop filter using this information, specifically by decoding uniform spacing flags and differential positional information to determine vertical and horizontal virtual boundary positions, and applying constraints to deblocking filtering, sample adaptive offset (SAO) filtering, and adaptive loop filtering (ALF) as needed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If in-loop filter is applied to virtual boundaries in 360-degree video encoding, then image quality is improved, but performance deteriorates due to frame packing discontinuities

Engineering Contradiction:

Improveimage qualityVSAvoidperformance stability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies different filtering strategies to different regions: in-loop filtering is applied to real boundaries while being constrained or disabled at virtual boundaries caused by frame packing. This local differentiation allows quality improvement in appropriate areas while avoiding performance deterioration at problematic discontinuous boundaries.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent dynamically adjusts the in-loop filter operation based on boundary type detection. The system determines whether a boundary is a real boundary or a virtual boundary and selectively enables or constrains filtering accordingly, making the filtering process adaptive rather than static.

Inventive Principle:

Principle #15Dynamics

2Reliability

If in-loop filtering is constrained on virtual boundaries, then performance deterioration is prevented, but image quality enhancement is reduced

Engineering Contradiction:

Improveperformance stabilityVSAvoidimage quality

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

3Ease of operation

If virtual boundary information is signaled and processed, then filter constraint operation is improved, but device complexity increases

Engineering Contradiction:

Improvefilter constraint operationVSAvoidencoding/decoding complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent performs preliminary detection and classification of boundaries during the encoding/decoding process. By identifying virtual boundaries in advance and signaling their positions, the system prepares the necessary information before applying in-loop filtering, enabling the filter constraint operation to proceed smoothly without complex real-time decisions.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12069285B2Method for constraining an in-loop filter on a 360-degree video virtual edge

Publication Date: 2024.08.20 HYUNDAI MOTOR CO LTD

AI summary

Disclosed is a method for signaling virtual boundary information and constraining an operation of an in-loop filter on a virtual boundary by using the signaled boundary information in order to prevent performance deterioration which may occur when applying the in-loop filter for a discontinuous boundary (or virtual boundary) depending on frame packing in an encoding/decoding of a 360-degree omnidirectional video.