360 VR Video Encoding with Dynamic Projection Layout Signaling
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Solution Overview
Problem
Current video encoding technologies lack flexibility in encoding 360-degree image content, as they are restricted by a fixed 360 VR projection layout, limiting bitrate reduction and efficiency in representing omnidirectional video for virtual reality applications.
Innovation Solution
A video encoding method and apparatus that allows for the selection and signaling of a 360 VR projection layout, including triangular projection faces, through syntax element signaling, enabling dynamic configuration and adjustment of the projection layout during encoding and decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed 360 VR projection layout is used, then the encoding process is simplified, but the flexibility for encoding 360-degree image content is reduced
Solution Approach 1:
The patent implements dynamic projection layout configuration by allowing the video encoder to select from multiple predefined projection layouts (e.g., equirectangular, cubic, spherical) and signal the selected layout type through syntax elements in the bitstream. This enables the encoding system to adaptively choose the most appropriate projection layout for each 360-degree video content based on characteristics such as field of view, resolution requirements, and content type, rather than being constrained to a single fixed layout.
2Device complexity
If a fixed projection layout is used, then the encoder design is simpler, but bitrate reduction efficiency is limited
Solution Approach 1:
The patent enables bitrate reduction efficiency improvement by allowing changes in projection layout parameters such as field of view angles, resolution分配 (resolution allocation) across different regions, and projection type selection. The encoder can optimize these parameters based on content characteristics—for example, allocating higher resolution to regions of interest or using different projection types for different content types—thereby achieving better compression efficiency compared to a fixed layout approach.
3Adaptability or versatility
If syntax element signaling is implemented for projection layout configuration, then flexibility is improved, but device complexity increases
Solution Approach 1:
The patent implements a balanced approach to syntax element signaling by providing detailed configuration options only when needed. The system includes a flag-based mechanism that allows optional signaling of projection layout parameters—if the default layout is used, no additional syntax elements are signaled; if custom configuration is required, then the relevant syntax elements are signaled. This partial action approach provides flexibility when needed while minimizing complexity for standard cases.
Data Source
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AI summary
A video encoding method includes: setting a 360-degree Virtual Reality (360 VR) projection layout of projection faces, wherein the projection faces have a plurality of triangular projection faces located at a plurality of positions in the 360 VR projection layout, respectively; encoding a frame having a 360-degree image content represented by the projection faces arranged in the 360 VR projection layout to generate a bitstream; and for each position included in at least a portion of the positions, signaling at least one syntax element via the bitstream, wherein the at least one syntax element is set to indicate at least one of an index of a triangular projection view filled into a corresponding triangular projection face located at the position and a rotation angle of content rotation applied to the triangular projection view filled into the corresponding triangular projection face located at the position.