History-Based Motion Candidate Lists for Video Half-Pixel Filter Selection
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Solution Overview
Problem
The increased signaling overhead and reduced coding efficiency in video coding due to the use of switchable interpolation filters for half-pixel positions, particularly in Versatile Video Coding (VVC), necessitate improved methods for selecting appropriate interpolation filters based on motion vector accuracy.
Innovation Solution
A history-based motion information candidate list is constructed to inherit and propagate the half-pixel interpolation filter index, allowing selection of appropriate filters for blocks coded in skip/merge modes, thereby improving prediction signal quality and coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switchable interpolation filters are used for half-pixel positions in VVC, then prediction signal quality is improved, but signaling overhead is increased
Solution Approach 1:
The system uses the motion information candidate list to automatically determine and inherit the interpolation filter index without requiring explicit signaling. The decoder derives the appropriate filter index from the motion information candidates, allowing the system to self-determine the correct filter without additional overhead.
Solution Approach 2:
The motion information candidate list acts as an intermediary that carries implicit filter index information. Instead of directly signaling the filter index, the system uses the motion information candidates as a mediator to convey the necessary filter selection information indirectly.
2Reliability
If switchable interpolation filters are used for half-pixel positions, then prediction signal quality is improved, but coding efficiency is reduced
Solution Approach 1:
The system automatically determines the interpolation filter index from the motion information candidate list without requiring additional signaling bits. This self-determination mechanism eliminates the need for explicit filter index signaling, thereby improving coding efficiency while maintaining prediction quality.
Solution Approach 2:
The filter index information is extracted from the motion information candidate list rather than being separately signaled. By taking out the filter index from the traditional signaling path and embedding it in the motion information candidates, the system reduces overhead and improves coding efficiency.
3Loss of information
If default interpolation filter is used, then signaling overhead is reduced, but prediction signal quality deteriorates
Solution Approach 1:
The motion information candidate list serves as an intermediary that carries filter index information implicitly. This allows the system to avoid using the default filter and instead select the appropriate filter based on motion characteristics, without requiring explicit signaling.
Solution Approach 2:
The system uses feedback from the motion information candidate list to determine the appropriate interpolation filter index. The motion information candidates provide feedback about the appropriate filter to use, allowing the system to adaptively select filters based on actual motion characteristics rather than relying on defaults.
Data Source
AI summary
The present disclosure relates to video encoding and decoding, and in particular, a method for inter prediction for a block in a frame of a video signal includes: constructing a history-based motion information candidate list, wherein the list is an ordered list comprising N history-based motion information candidates Hk containing motion information of N preceding blocks preceding the block, wherein each history-based motion information candidate comprises: one or more motion vectors (MVs), one or more reference picture indices corresponding to the MVs, and an interpolation filter index; adding one or more history-based motion information candidates from the history-based motion information candidate list into a motion information candidate list for the block; and deriving motion information for the block based on the motion information candidate list