Joint Motion Vector Coding for Lower-Bit Inter Prediction
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Solution Overview
Problem
Existing video coding technologies face inefficiencies in representing and encoding motion vector differences, particularly in intra and inter prediction modes, leading to suboptimal compression ratios and increased data requirements.
Innovation Solution
The implementation of joint delta motion vector signaling for inter-predicted video blocks, where a single joint delta motion vector is used to derive both delta motion vectors from a first and second reference frame, enhancing compression efficiency by reducing the bit representation of motion vectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If separate delta motion vectors are signaled for first and second reference frames, then prediction accuracy is maintained, but bit representation and data requirements increase
Solution Approach 1:
The patent combines separate delta motion vectors for first and second reference frames into a single joint delta motion vector. This merging approach reduces the bit representation from signaling two independent vectors to signaling one shared vector, thereby reducing data requirements while maintaining prediction accuracy through the joint derivation process.
Solution Approach 2:
The joint delta motion vector serves multiple functions by being used to derive both the first delta motion vector (for the first reference frame) and the second delta motion vector (for the second reference frame). This multi-functionality eliminates redundancy and reduces the overall bit representation without sacrificing the ability to accurately represent motion in either reference frame.
2Productivity
If joint delta motion vector is used to derive both delta motion vectors, then compression efficiency improves, but derivation complexity increases
Solution Approach 1:
The patent changes the parameter representation from two separate delta motion vectors to a single joint delta motion vector. This parameter change enables more efficient compression by reducing the total number of bits required, while the derivation process transforms the joint vector into the individual delta vectors needed for each reference frame through defined mathematical operations.
Data Source
AI summary
This disclosure relates encoding and decoding of motion vector difference in for inter-predicting a video block. An example is disclosed for decoding an inter-predicted video block of a video stream. The method includes receiving a coded video bitstream; extracting, from the coded video bitstream, an inter prediction mode and a joint delta motion vector (MV) for a current block in a current frame; extracting, from the coded video bitstream, a flag indicating whether a first delta MV for a first reference frame and a second delta MV for a second reference frame are jointly signaled; in response to the flag indicating that the first delta MV and the second delta MV are jointly signaled, deriving the first delta MV and the second delta MV based on the joint delta MV; and decoding the current block in the current frame based on the first delta MV and the second delta MV.