Mapping-Aware Coding Tools for 360 Degree Video
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Solution Overview
Problem
Conventional video coding tools are not adapted for encoding and decoding 360 degree video data, which uses a spherical projection, leading to disproportionate scaling and distortion due to the mapping of video data to and from a spherical shape.
Innovation Solution
The implementation of mapping-aware coding tools that perform motion vector mapping, adaptive motion search, adaptive interpolation filter selection, and adaptive block partitioning, taking into account the spherical projection of 360 degree video data to address scaling and distortion issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional video coding tools are used for 360 degree video encoding, then the encoding process is simple, but the video quality deteriorates due to disproportionate scaling and distortion from spherical projection mapping
Solution Approach 1:
The patent applies parameter changes by adapting motion vector calculation parameters to account for spherical projection characteristics. Specifically, it modifies the motion compensation process to use rotation parameters and spherical coordinate transformations, allowing the coding tool to maintain video quality while handling the geometric distortion inherent in 360 degree video encoding
Solution Approach 2:
The patent segments the encoding process into distinct stages: spherical projection mapping, motion vector calculation in spherical coordinates, and inverse mapping. This segmentation allows each stage to be optimized independently, improving overall video quality without requiring complete redesign of the entire coding system
2Measurement precision
If motion vector mapping on sphere is implemented, then the motion prediction accuracy is improved, but the computational complexity increases
Solution Approach 1:
The patent performs preliminary action by pre-calculating rotation parameters and spherical mapping transformations that are then reused during motion compensation. This approach improves motion prediction accuracy by establishing accurate geometric relationships in advance, while reducing real-time computational power requirements by avoiding redundant calculations
Data Source
AI summary
Mapping-aware coding tools for 360 degree videos adapt conventional video coding tools for 360 degree video data using parameters related to a spherical projection of the 360 degree video data. The mapping-aware coding tools perform motion vector mapping techniques, adaptive motion search pattern techniques, adaptive interpolation filter selection techniques, and adaptive block partitioning techniques. Motion vector mapping includes calculating a motion vector for a pixel of a current block by mapping the location of the pixel within a two-dimensional plane (e.g., video frame) onto a sphere and mapping a predicted location of the pixel on the sphere determined based on rotation parameters back onto the plane. Adaptive motion searching, adaptive interpolation filter selection, and adaptive block partitioning operate according to density distortion based on locations along the sphere. These mapping-aware coding tools contemplate changes to video information by the mapping of 360 degree video data into a conventional video format.