Motion Vector Scaling with Extended Clipping Range
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing motion vector predictor scaling in High Efficiency Video Coding (HEVC) has an insufficient effective scaling ratio, which limits its ability to accommodate reference pictures with longer temporal distances, leading to parsing errors and coding performance issues.
Innovation Solution
Increasing the effective scaling ratio for motion vector scaling by modifying the clipping values in the scaling factor equations to achieve a range of [-8, 8), [-16, 16), or [-32, 32), allowing for more extensive picture distance considerations and improved MVP derivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the effective scaling ratio is increased to accommodate reference pictures with longer temporal distances, then the coding efficiency and performance are improved, but the complexity of the motion vector scaling apparatus increases
Solution Approach 1:
The patent implements dynamic scaling ratio selection by determining whether to apply a first scaling ratio or a second scaling ratio based on the temporal distance between reference pictures. The apparatus dynamically adjusts the scaling behavior according to the specific coding scenario, allowing optimal performance across varying picture distances without requiring a fixed complex structure for all cases.
Solution Approach 2:
The patent uses motion vector copying from candidate blocks with scaling to derive motion vectors for the current block. By copying and scaling motion vectors from temporally distant reference pictures, the system achieves improved coding efficiency for long temporal distances without requiring completely new motion estimation mechanisms.
2Reliability
If clipping values in scaling factor equations are modified to achieve a wider scaling ratio range, then parsing errors are reduced, but the manufacturing precision of the scaling factor calculation is affected
Solution Approach 1:
The patent changes the clipping range parameter of the scaling factor from the traditional limited range to an extended range [-32, 32). This parameter change allows the scaling factor to accommodate larger temporal distances without overflow, reducing parsing errors while maintaining calculation precision through appropriate data type selection and overflow handling mechanisms.
3Adaptability or versatility
If the scaling ratio range is extended to accommodate longer temporal distances, then the adaptability of the motion vector prediction is improved, but the difficulty of detecting and measuring the scaling factor increases
Solution Approach 1:
The patent segments the motion vector scaling process into distinct cases: one for temporally close reference pictures and another for temporally distant reference pictures. By dividing the problem into segments with different scaling ratios, the system improves adaptability to various temporal distances while simplifying the detection and calculation for each specific case.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A method and apparatus for deriving a scaled MV (motion vector) for a current block based on a candidate MV associated with a candidate block are disclosed. Embodiments according to the present invention increase effective scaling factor of motion vector scaling. In one embodiment, a distance ratio of a first picture distance between a current picture and a target reference picture pointed to by a current motion vector of the current block to a second picture distance between a candidate picture corresponding to the candidate block and a candidate reference picture pointed to by the candidate MV is computed. The scaled MV is then generated based on the candidate MV according to the distance ratio, where the scaled MV has an effective scaling ratio between -m and n, and wherein m and n are positive integers greater than 4. The values of m and n can be 8, 16 or 32.