Intra-block Copy Search for Screen Content

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Solution Overview

Problem

Current screen content sharing applications face challenges in efficiently compressing high-definition and ultra-high-definition content, leading to visible artifacts and increased bandwidth usage due to the inefficiencies in video coding technologies optimized for natural video rather than screen content.

Innovation Solution

The implementation of IntraBC (Intra-block Copy) search methods, including predictor-based and hash-based searches, to improve coding efficiency by utilizing reconstructed pixels and adaptive block vector predictions, reducing the complexity of search processes and enhancing prediction accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If IntraBC search is performed for all blocks to improve compression quality, then coding efficiency improves, but computational complexity increases

Engineering Contradiction:
Improvecoding efficiencyVSAvoidcomputational complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the IntraBC search threshold based on block characteristics. The threshold is modified according to the block's position, size, and content properties, allowing the encoder to perform exhaustive search only when beneficial while using simplified search for other blocks, thus resolving the contradiction between compression quality and computational complexity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements partial action by selectively applying IntraBC search only to blocks that meet specific criteria (e.g., blocks with high similarity to reference blocks, blocks in specific regions). This partial application of the search mechanism maintains coding efficiency for suitable blocks while reducing overall computational complexity across the entire video stream

Inventive Principle:
Principle #16Partial or excessive action

2Manufacturing precision

If IntraBC search threshold is lowered to improve prediction accuracy, then artifact reduction improves, but processing time increases

Engineering Contradiction:
Improveprediction accuracyVSAvoidprocessing time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent dynamically changes the search threshold parameter based on block characteristics such as position, size, and content type. By adapting the threshold to each block's specific properties rather than using a fixed low threshold, the system achieves high prediction accuracy where needed while maintaining faster processing for blocks where exhaustive search is unnecessary

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary analysis of block characteristics before determining the search threshold. By pre-evaluating block properties and predicting which blocks will benefit from low-threshold search, the system avoids unnecessary processing time while ensuring prediction accuracy is maintained for blocks where it will have the greatest impact

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3251350B1Intra-block copy searching
Publication Date: 2023.04.19 VID SCALE INC
  • EP3251350B1 patent drawingFigure 1
  • EP3251350B1 patent drawingFigure 2
  • EP3251350B1 patent drawingFigure 3

AI summary

A video coding device may encode a video signal using intra-block copy prediction. A first picture prediction unit of a first picture may be identified. A second picture may be coded and identified. The second picture may be temporally related to the first picture, and the second picture may include second picture prediction units. A second picture prediction unit that is collocated with the first picture prediction unit may be identified. Prediction information for the first picture prediction unit may be generated. The prediction information may be based on a block vector of the second picture prediction unit that is collocated with the first picture prediction unit.