Motion Vector Prediction Scaling for AVS2 Video Coding
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Solution Overview
Problem
In the AVS2 video coding standard, when a motion vector of a neighboring block points to a G or GB reference picture, the BlockDistance is undefined, leading to issues in motion vector prediction scaling and potentially degrading coding efficiency.
Innovation Solution
Assign a value of 1 to the BlockDistance for neighboring blocks whose reference picture is a G or GB picture, ensuring it is always defined, and use this defined BlockDistance to scale motion vector predictors for accurate prediction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If motion vector prediction scaling is performed using BlockDistance for neighboring blocks pointing to G or GB pictures, then coding efficiency is improved, but BlockDistance becomes undefined leading to prediction errors
Solution Approach 1:
The patent changes the parameter BlockDistance from an undefined state to a defined state by setting it to 1 when the reference picture is a G or GB picture. This parameter change resolves the contradiction by ensuring BlockDistance is always defined for scaling operations, maintaining both coding efficiency and prediction accuracy.
2Reliability
If BlockDistance is defined as 1 for G or GB reference pictures, then motion vector prediction scaling becomes reliable, but additional conditional logic increases processing complexity
Solution Approach 1:
The patent applies preliminary action by defining BlockDistance = 1 in advance for G or GB reference pictures before the scaling operation is needed. This conditional definition is performed as part of the motion vector prediction process, ensuring BlockDistance is ready and defined when scaling is required, thus maintaining reliability without significant additional complexity.
Data Source
AI summary
A method and apparatus for video encoding or decoding used by an AVS2 (Second Generation of Audio Video Coding Standard) video encoder or decoder respectively are disclosed. According to this method, first motion vectors associated with spatial neighboring blocks of a current block are determined. For each spatial neighboring block, a value of 1 is assigned to a first BlockDistance associated with the spatial neighboring block if a corresponding first reference picture is a G picture or GB picture. Motion vector predictor candidates are derived from the first motion vectors by scaling each first motion vector according to a corresponding first BlockDistance and a current BlockDistance. A final motion vector predictor is determined among the motion vector predictor candidates. The current motion vector is encoded or decoded using the final motion vector predictor