Affine Motion Vector Derivation for Chroma Components
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Solution Overview
Problem
Existing video coding techniques struggle to efficiently encode and decode high-definition and ultra-high-definition video data while maintaining image quality, particularly in deriving motion vectors for chroma components.
Innovation Solution
The method involves deriving affine motion vectors for chroma components by averaging the motion vectors of corresponding luma subblocks, utilizing a quadtree with nested multi-type tree structure and applying control point motion vector prediction to enhance coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional motion vector derivation methods are used for chroma components, then the encoding process is simpler, but coding efficiency deteriorates and bit rate increases
Solution Approach 1:
The patent introduces an intermediate process of deriving affine motion vectors for chroma components from luma motion vectors before final motion compensation. This intermediary step enables better prediction accuracy by utilizing the relationship between luma and chroma components, thereby improving coding efficiency without requiring complete redesign of the encoding system
Solution Approach 2:
The patent segments the motion vector derivation process into distinct stages: luma motion vector derivation, affine transformation application, and chroma motion vector assignment. This segmentation allows each stage to be optimized independently while maintaining overall system efficiency and managing complexity through modular processing
2Manufacturing precision
If high-definition and ultra-high-definition video data is encoded with detailed motion vectors, then video quality is maintained, but bit rate increases
Solution Approach 1:
The patent changes the parameters of motion vector derivation by applying affine transformations to chroma motion vectors based on luma motion vectors. This parameter transformation enables more accurate motion prediction for chroma components in high-definition and ultra-high-definition video, maintaining video quality while reducing the information needed to be transmitted
Solution Approach 2:
The patent copies motion vector information from luma components to chroma components through affine transformation. By reusing and transforming existing luma motion vectors rather than encoding completely new chroma motion vectors, the system maintains prediction accuracy for high-definition video while significantly reducing bit rate requirements
Data Source
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AI summary
A method for video encoding, comprising: arranging video data in luma subblocks and chroma subblocks, wherein the video data has a color sampling format, and each chroma subblock corresponds to one or more luma subblocks, deriving an affine motion vector for a chroma subblock using an average luma motion vector obtained by averaging motion vectors of the corresponding luma subblocks, predicting the chroma subblock and generating a video bitstream, wherein the corresponding luma subblocks are derived according to the color sampling format, wherein the averaging process uses the motion vectors from different luma subblocks under different color sampling formats, wherein for 4:4:4 color sampling format the average luma motion vector is the motion vector of one corresponding luma subblock, and for 4:2:2 color sampling format the average luma motion vector is obtained by taking an average of the motion vectors of two corresponding luma subblocks.