Motion Vector Difference Signaling for Inter Prediction
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Solution Overview
Problem
The increasing demand for high-resolution, high-quality images/videos, such as 4K or 8K, poses challenges in efficient compression, transmission, storage, and reproduction due to the high amount of information required, which increases transmission and storage costs.
Innovation Solution
The method and device for improving image/video coding efficiency by efficiently signaling information on motion vector differences, particularly when bi-prediction is applied, using specific reference picture types to derive symmetric motion vector differences, and using SMVD flags to indicate symmetric motion vector differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-resolution, high-quality image/video (4K or 8K) is used, then image quality is improved, but transmission cost and storage cost increase due to high amount of information
Solution Approach 1:
The patent segments motion information into motion vectors and motion vector differences (MVDs), further dividing MVDs into temperature-dependent components. This segmentation allows selective encoding of only necessary motion information, reducing overall data quantity while maintaining high-resolution image quality.
Solution Approach 2:
The patent changes the parameter representation by deriving motion vector differences based on temperature (reference picture type) rather than encoding all motion information independently. This parameter transformation reduces the amount of information needed to represent high-resolution video while preserving image quality.
2Productivity
If motion vector differences are signaled for bi-prediction, then inter prediction efficiency is improved, but signaling complexity increases
Solution Approach 1:
The patent transforms the signaling approach by parameterizing motion vector differences based on temperature (reference picture type). Instead of signaling complete motion information for bi-prediction, the system signals temperature-based MVD parameters that can be derived at the decoder, reducing signaling complexity while improving prediction efficiency.
Solution Approach 2:
The patent uses reference picture copying with temperature-based indexing to derive motion vector differences. The decoder copies and applies pre-defined temperature parameters corresponding to different reference picture types, reducing the need for complex signaling while maintaining accurate inter prediction.
3Productivity
If symmetric motion vector differences are derived using specific reference picture types, then compression efficiency is improved, but derivation complexity increases
Solution Approach 1:
The patent changes the derivation approach by introducing temperature as a parameter that indexes pre-defined motion vector difference patterns for different reference picture types. This parameter-based derivation simplifies the complexity while improving compression efficiency through more accurate symmetric motion modeling.
Solution Approach 2:
The patent performs preliminary classification of reference pictures into temperature categories (short-term, long-term, etc.) and pre-defines motion vector difference patterns for each type. This preliminary action allows the decoder to quickly derive symmetric MVDs without complex real-time calculations, improving compression efficiency while managing derivation complexity.
Data Source
AI summary
According to embodiments of the present document, a prediction procedure can be performed for image video coding, and the prediction procedure can comprise merge mode motion vector differences (MMVD) and symmetric motion vector differences (SMVD) according inter prediction. The inter prediction can be performed on the basis of reference pictures of a current picture, and types of the reference pictures (e.g. a long-term reference picture, a short-term reference picture, etc.) can be considered for the inter prediction. Accordingly, performance and coding efficiency in the prediction procedure can be increased.