Viewport-Based Cube Projection Layout for 360-Degree Video Encoding
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Solution Overview
Problem
The high bitrate required for representing 360-degree image/video content in virtual reality applications poses a challenge for efficient data compression and encoding, especially when the resolution is 4K or higher, leading to potential bottlenecks in content delivery.
Innovation Solution
A method and apparatus for generating and encoding projection-based frames using a viewport-based cube projection layout, which packs 360-degree content onto rectangular projection faces, allowing for a compact form and preserving the user's viewport content in a main projection face, thereby improving coding efficiency by eliminating dummy areas and optimizing data representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 360-degree omnidirectional content is represented with high resolution (4K or higher), then visual quality and immersive experience are improved, but bitrate requirements increase significantly
Solution Approach 1:
The patent divides the 360-degree omnidirectional content into multiple rectangular projection faces (typically six faces corresponding to the six faces of a cube) that can be independently encoded. This segmentation allows each face to be processed separately, enabling more efficient compression compared to treating the entire 360-degree content as a single large image, thus reducing the overall bitrate requirement while maintaining high resolution.
Solution Approach 2:
The patent transforms the spherical 360-degree content into a planar representation by projecting it onto multiple rectangular faces arranged in a specific layout. This dimensional transformation from a continuous sphere to discrete planar faces enables the application of conventional 2D video coding techniques, significantly improving compression efficiency and reducing bitrate while preserving visual quality.
2Ease of manufacture
If conventional projection layouts are used for 360-degree content, then simplicity of implementation is maintained, but coding efficiency decreases due to dummy areas and non-compact forms
Solution Approach 1:
The patent merges multiple rectangular projection faces into a single compact planar layout by arranging them in a specific configuration. This merging eliminates the need for separate processing of multiple independent files or data structures, maintaining implementation simplicity while achieving a compact form that removes dummy areas and improves coding efficiency through better spatial utilization.
Solution Approach 2:
The patent introduces a dynamic viewport-based approach where the projection layout can be adaptively adjusted based on the user's viewing direction and field of view. This allows the system to dynamically reposition and reconfigure the rectangular faces to prioritize the visible viewport area, improving coding efficiency by concentrating computational resources on the most relevant content while maintaining ease of implementation through standardized transformation operations.
Data Source
AI summary
A video processing method includes: receiving an omnidirectional image/video content corresponding to a viewing sphere, generating a sequence of projection-based frames according to the omnidirectional image/video content and a viewport-based cube projection layout, and encoding the sequence of projection-based frames to generate a bitstream. Each projection-based frame has a 360-degree image/video content represented by rectangular projection faces packed in the viewport-based cube projection layout. The rectangular projection faces include a first rectangular projection face, a second rectangular projection face, a third rectangular projection face, a fourth rectangular projection face, a fifth rectangular projection face, and a sixth rectangular projection face split into partial rectangular projection faces. The first rectangular projection face corresponds to user's viewport, and is enclosed by a surrounding area composed of the second rectangular projection face, the third rectangular projection face, the fourth rectangular projection face, the fifth rectangular projection face, and the partial rectangular projection faces.