Block Vector Prediction for Efficient Intra-Block Copy Coding

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Solution Overview

Problem

The HEVC standard's intra block copy prediction mode inefficiencies include inefficient signaling of block vector (BV) values and inadequate handling of blocks with predictable displacements.

Innovation Solution

Implementing a default BV predictor with a non-zero value, using a selected BV predictor candidate, and employing a skip mode for intra-BC-predicted blocks to enhance coding efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If intra block copy prediction mode is implemented with conventional BV signaling, then block displacement prediction can be performed, but BV values are not signaled efficiently and coding efficiency is reduced

Engineering Contradiction:

ImproveBV value signaling efficiencyVSAvoidcoding efficiency

Core Design Contradiction:

Loss of informationVSProductivity

Solution Approach 1:

The patent applies preliminary action by introducing a default BV predictor that is pre-established and can be directly used without requiring full BV signaling. This default predictor is set up in advance based on neighboring block information, allowing the encoder to signal only when the actual BV differs from the default, thereby improving signaling efficiency and coding productivity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the parameter representation by introducing a BV differential (difference between actual BV and default BV predictor) instead of signaling the complete BV value. This parameter transformation allows for more efficient encoding when the BV is close to the predictor, reducing the number of bits required and improving overall coding efficiency

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional BV signaling is used without prediction, then implementation is simple, but blocks with predictable displacements are not handled efficiently

Engineering Contradiction:

Improveimplementation simplicityVSAvoidpredictable block displacement handling

Core Design Contradiction:

Ease of manufactureVSLoss of information

Solution Approach 1:

The patent implements feedback by using the BV values of previously decoded neighboring blocks to construct a default BV predictor for the current block. This feedback mechanism allows the system to learn from past predictions and improve current signaling efficiency, handling predictable displacements more effectively while maintaining reasonable implementation complexity

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies self-service by enabling the decoding process to generate its own prediction information from previously decoded data. The default BV predictor is derived automatically from neighboring block BVs that are already available in the decoded picture buffer, eliminating the need for separate prediction information signaling and improving efficiency for predictable blocks

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS12413771B2Block vector prediction in video and image coding/decoding

Publication Date: 2025.09.09 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

Innovations in the area of prediction of block vector (“By”) values improve encoding or decoding of blocks using intra block copy (“BC”) prediction. For example, some of the innovations relate to use of a default BV predictor with a non-zero value. Other innovations relate to use of a selected one of multiple BV predictor candidates for a current block. Still other innovations relate to use of a skip mode in which a current intra-BC-predicted block uses a predicted BV value.