Mean Motion Vector Predictor for Video Coding
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Solution Overview
Problem
In video coding systems like HEVC, the fixed candidate list size for motion vector prediction can lead to parsing errors and decoding failures due to mismatch between encoder and decoder sides, especially when temporal motion candidates are involved, affecting the coding efficiency and video quality.
Innovation Solution
The proposed solution involves generating a mean motion vector predictor by averaging motion vectors from neighboring blocks in predefined lists, which is added to the candidate list to improve coding efficiency and reduce parsing errors, allowing for dynamic list sizes and adaptive encoding/decoding in Inter, Merge, or Skip modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed candidate list size is used for motion vector prediction, then the decoding process is simplified and faster, but parsing errors and decoding failures occur due to mismatch between encoder and decoder sides
Solution Approach 1:
The patent implements dynamic candidate list size adjustment based on the availability of motion vector predictors. The candidate list size is no longer fixed but adapts to the actual number of available predictors, preventing encoder-decoder mismatches. This is achieved by allowing the list size to vary between 1 and 5 candidates depending on the prediction mode and available reference blocks.
2Measurement precision
If temporal motion candidates are added to the candidate list, then the motion prediction accuracy is improved, but parsing errors occur due to encoder-decoder mismatch
Solution Approach 1:
The patent implements a feedback mechanism where the encoder and decoder both calculate the same candidate list using identical rules, ensuring consistency. The candidate list is constructed by systematically evaluating spatial and temporal predictors in a predefined order, with both encoder and decoder following the same logic to generate matching lists without requiring additional signaling.
3Productivity
If the candidate list includes more motion vector predictors, then the coding efficiency is improved, but the processing complexity and potential for parsing errors increases
Solution Approach 1:
The patent changes the parameter of candidate list size from a fixed value to a dynamic parameter that adjusts based on the prediction mode and available reference blocks. For example, in Merge mode with 5 available predictors, the list size becomes 5, while in Skip mode or when fewer predictors are available, the list size reduces accordingly. This parameter adaptation optimizes coding efficiency while managing complexity.
Data Source
AI summary
A method and apparatus for video coding utilizing a motion vector predictor (MVP) for a motion vector (MV) for a block are disclosed. According to an embodiment, a mean candidate is derived from at least two candidates in the current candidate list. The mean candidate includes two MVs for the bi-prediction or one MV for the uni-prediction, and at least one MV of the mean candidate is derived as a mean of the MVs of said at least two candidates in one of list 0 and list 1. The mean candidate is added to the current candidate list to form a modified candidate list, and one selected candidate is determined as a MVP or MVPs from the modified candidate list, for current MV or MVs of the current block. The current block is then encoded or decoded in Inter, Merge, or Skip mode utilizing the MVP or MVPs selected.