Motion Vector Difference Signaling in Bi-Predictive Video Coding
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Solution Overview
Problem
The increasing demand for high-resolution, high-quality images and videos, particularly in virtual reality and augmented reality, leads to higher data transmission and storage costs due to the increased amount of information required, necessitating a more efficient compression technique.
Innovation Solution
A method and apparatus for motion vector prediction-based image/video coding that includes signaling information about motion vector differences and using bi-prediction, with features like L1 motion vector difference zero flags and SMVD flags to enhance coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-resolution, high-quality image/video is transmitted or stored, then image/video quality is improved, but transmission and storage costs increase due to increased amount of information
Solution Approach 1:
The patent applies parameter changes by transforming the representation of motion vectors from absolute values to differential values (motion vector differences). This changes the parameter encoding approach to reduce the number of bits needed while maintaining quality information. The motion vector difference is derived by subtracting a predicted motion vector from the actual motion vector, allowing for more efficient encoding of high-resolution video data.
Solution Approach 2:
The patent extracts only the essential information needed for motion vector representation by using prediction techniques. Instead of transmitting complete motion vector data, the system extracts and transmits only the difference components (MVD) after predicting the motion vector from neighboring blocks. This extraction approach reduces the quantity of transmitted information while preserving the necessary quality details.
2Productivity
If motion vector prediction is used to reduce information amount, then compression efficiency is improved, but complexity of information signaling may increase
Solution Approach 1:
The patent segments the motion vector signaling into distinct components: prediction information (derived from neighboring blocks) and difference information (explicitly signaled). This segmentation allows the system to handle complexity by processing prediction and residual components separately, improving compression efficiency while managing signaling complexity through structured decomposition of the motion vector data.
Solution Approach 2:
The patent introduces motion vector difference (MVD) as an intermediary representation between the actual motion vector and the predicted motion vector. This intermediary component simplifies the signaling process by focusing only on the residual information that needs to be transmitted, rather than transmitting the complete motion vector, thus improving compression efficiency with manageable complexity.
3Measurement precision
If bi-prediction is applied to current block, then prediction accuracy is improved, but amount of prediction-related information to be signaled increases
Solution Approach 1:
The patent applies partial action by signaling only the essential prediction-related information needed for bi-prediction rather than all possible information. The motion vector difference is calculated and signaled only when necessary, and the prediction process uses only the required neighboring block information. This partial approach maintains prediction accuracy while minimizing the amount of information that needs to be transmitted.
Data Source
AI summary
An image decoding method according to the present document comprises: decoding a current block on the basis of image information, wherein an MVP candidate list for the current block is derived on the basis of an inter prediction mode, which is derived on the basis of image information, and peripheral blocks of the current block; and deriving motion information of the current block on the basis of the MVP candidate list, wherein the peripheral blocks include a left bottom corner peripheral block, a left peripheral block, a right top corner peripheral block, a top peripheral block, and a left top corner peripheral block of the current block, the motion information includes an L0 motion vector for L0 prediction and/or an L1 motion vector for L1 prediction, the L0 motion vector is derived on the basis of an L0 motion vector predictor and an L0 motion vector difference, and the L1 motion vector is derived on the basis of an L1 motion vector predictor and an L1 motion vector difference.