Video Encoder Sub-Block Deblocking for Boundary Distortion

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Solution Overview

Problem

Existing video encoding technologies, such as H.265, face challenges in reducing boundary distortion when performing prediction processes on a per sub-block basis, particularly in advanced temporal motion vector prediction (ATMVP) modes, where misalignment of object boundaries can lead to image quality degradation.

Innovation Solution

The encoder and decoder apply a deblocking filter to the boundaries of sub-blocks, specifically an 8×8 pixel region, using a stronger filter if necessary, to reduce boundary distortion in the prediction image.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a boundary smoothing process is applied to all sub-block boundaries, then boundary distortion is reduced, but processing complexity and computational load increase

Engineering Contradiction:

Improveboundary distortion reductionVSAvoidprocessing complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies boundary smoothing selectively only to specific sub-block boundaries (those at integer multiples of 8 pixels) rather than all boundaries. This local approach reduces computational complexity while maintaining effective boundary distortion reduction where most needed, resolving the contradiction between processing precision and complexity.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If prediction is performed on a per sub-block basis, then image quality is improved, but boundary misalignment and distortion occur

Engineering Contradiction:

Improveimage qualityVSAvoidboundary alignment

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies boundary smoothing as a preliminary correction step before final image reconstruction. By pre-processing the prediction image to smooth boundaries at critical locations, it prevents boundary misalignment artifacts from appearing in the final output, thus maintaining both high image quality and boundary reliability.

Inventive Principle:

Principle #9Preliminary anti-action

3Manufacturing precision

If deblocking filter is applied strongly to reduce boundary distortion, then image clarity improves, but processing time increases

Engineering Contradiction:

Improveimage clarityVSAvoidprocessing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent applies deblocking filter with appropriate strength only to necessary boundaries (those at integer multiples of 8) rather than uniformly to all boundaries. This partial application achieves sufficient image clarity improvement while minimizing processing time, resolving the contradiction between image quality and processing speed.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20250379999A1Encoder, decoder, encoding method, and decoding method

Publication Date: 2025.12.11 PANASONIC INTELLECTUAL PROPERTY CORP OF AMERICA

AI summary

An encoder that encodes a video includes circuitry and memory connected to the circuitry. In operation, the circuitry: generates a prediction image on a per sub-block basis; and when a sub-block size is 4×4, applies a boundary smoothing process only to sub-block boundaries having boundary positions that are integer multiples of 8.