Decoder-Side Motion Derivation for Low-Overhead Video Coding

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Solution Overview

Problem

The existing video coding standards, such as VVC, face challenges in managing high signalling overhead associated with Motion Vector Difference (MVD) for Motion Vector Predictors (MVP), which affects coding efficiency.

Innovation Solution

The method employs template matching to determine Motion Vector Predictors (MVPs) and Motion Vector Differences (MVDs) by calculating matching costs between neighboring samples and reference blocks, reducing the need for explicit signalling of MVDs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If explicit MVD signalling is used for MVP, then motion prediction accuracy is improved, but signalling overhead increases

Engineering Contradiction:

Improvemotion prediction accuracyVSAvoidsignalling overhead

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The decoder derives MVD values independently using template matching on its own side without requiring explicit transmission from the encoder. The decoder uses the transmitted MVP and locally computed template matching results to self-determine the final motion vector, eliminating the need for encoder-to-decoder MVD signalling.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Template matching serves as an intermediary mechanism between the transmitted MVP and the final motion vector. Instead of directly signalling MVD, the system uses template matching costs as an intermediate step to indirectly derive the motion vector at the decoder side.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If template matching is performed at encoder side, then MVD determination accuracy is improved, but computational complexity increases

Engineering Contradiction:

ImproveMVD determination accuracyVSAvoidcomputational complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of performing template matching at the encoder side to determine MVD, the invention inverts the approach by having the decoder perform the template matching. This shifts the computational burden from encoder to decoder, resolving the contradiction between accuracy and encoder complexity.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The invention replaces the mechanical encoder-side template matching process with a decoder-side derivation process that uses pre-transmitted MVP and locally computed matching costs, substituting one computational approach with another that better balances complexity and accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS20250294180A1Method and Apparatus for Decoder-Side Motion Derivation in Video Coding System

Publication Date: 2025.09.18 MEDIATEK INC

AI summary

A method and apparatus for video coding. According to this method, at least one of a first MVP and a second MVP for the current block is determined. At least one of a first MVD associated with the first MVP and a second MVD associated the second MVP from at least one pre-defined set of MVD candidates is determined based on matching costs. Each of the matching costs is determined between neighbouring samples of the current block and predicted samples from corresponding neighbouring samples of each reference block associated with a candidate of said at least one pre-defined set of MVD candidates. The current block is encoded or decoded by using motion information comprising at least one of a first final MV associated with the first MVP and the first MVD, and a second final MV associated with the second MVP and the second MVD.