360-Degree Video Projection Format Signaling
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Solution Overview
Problem
Current VR systems face challenges in providing an immersive experience due to limitations in 360-degree video encoding and decoding, including insufficient resolution, discomfort from current HMDs, and inefficiencies in haptic feedback, which affect interactivity and overall user experience.
Innovation Solution
The method involves encoding 360-degree video using various projection formats such as equirectangular, cubemap, and octahedron, signaling geometry and frame packing parameters in the bitstream to optimize encoding and decoding, allowing for different faces to have varying quality and orientation, and using advanced syntax elements to enhance compression efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If 360-degree video is encoded using traditional projection formats, then the encoding process is simple, but the user experience is not immersive and resolution is insufficient
Solution Approach 1:
The patent segments the 360-degree video into multiple planar regions (front, back, left, right, top, bottom faces) and encodes each region separately with its own quality parameters. This allows different resolution and quality levels for different parts of the spherical video, improving overall quality while managing complexity through modular processing of discrete regions rather than treating the entire sphere as a single complex unit.
Solution Approach 2:
The patent applies local quality enhancement by allowing different quality parameters (resolution, bit rate, compression level) to be assigned to different planar regions of the 360-degree video. Regions that are more likely to be viewed (such as the front face) can be encoded at higher quality, while less frequently viewed regions use lower quality, thereby improving perceived user experience while optimizing resource allocation.
2Manufacturing precision
If high resolution 360-degree video is provided, then user experience improves, but bit rate requirements increase
Solution Approach 1:
The patent implements differential quality encoding where different planar regions are assigned different quality levels and bit rates based on their importance and expected viewing frequency. This allows the system to provide high resolution where needed (improving user experience) while reducing or skipping encoding of less important regions, thereby controlling overall bit rate consumption.
Solution Approach 2:
The patent encodes only the necessary portions of the 360-degree video at high quality, rather than uniformly encoding the entire sphere. By selectively applying high-quality encoding to specific planar regions that are most likely to be viewed and using lower quality or skipping encoding for other regions, the system achieves high perceived resolution while minimizing total bit rate requirements.
3Adaptability or versatility
If multiple projection formats are supported, then adaptability improves, but device complexity increases
Solution Approach 1:
The patent divides the complex task of supporting multiple projection formats into manageable segments by representing all formats as compositions of basic planar regions (faces). The encoder processes each planar region independently and signals the composition rules in the bitstream, allowing the decoder to reconstruct different projection formats (equirectangular, cubemap, octahedron, etc.) by assembling the same set of planar regions according to different rules, thereby achieving format versatility without proportionally increasing processing complexity.
Data Source
AI summary
Coding techniques for 360-degree video are described. An encoder selects a projection format and maps the 360-degree video to a 2D planar video using the selected projection format. The encoder encodes the 2D planar video in a bitstream and further signals, in the bitstream, parameters identifying the projection format. The parameters identifying the projection format may be signaled in a video parameter set, sequence parameter set, and/or picture parameter set of the bitstream. Different projection formats that may be signaled include formats using geometries such as equirectangular, cubemap, equal-area, octahedron, icosahedron, cylinder, and user-specified polygon. Other parameters that may be signaled include different arrangements of geometric faces or different encoding quality for different faces. Corresponding decoders are also described. In some embodiments, projection parameters may further include relative geometry rotation parameters that define an orientation of the projection geometry.