360-Degree Video Coding with Cross-Face Boundary Continuity
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Solution Overview
Problem
Existing video codecs struggle to efficiently encode and decode 360-degree videos due to the challenges posed by spherical geometry and uneven sampling density, leading to inefficient compression and viewer discomfort from inadequate resolution and haptic feedback.
Innovation Solution
The use of geometric projections like cubemap and equirectangular projection, combined with chroma subsampling and geometry padding, to transform 360-degree videos into a 2D format for efficient encoding and decoding, while maintaining viewer experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 360-degree video is encoded using traditional video codecs, then the encoding process is simple, but the compression efficiency is poor and bandwidth requirements are high
Solution Approach 1:
The patent segments the 360-degree video into multiple spherical blocks arranged in a specific pattern (e.g., 4x4 grid). Each block is processed independently with tailored encoding parameters, allowing efficient compression while maintaining overall video quality. This segmentation resolves the contradiction by enabling specialized compression techniques for different regions without requiring complete re-encoding of the entire video.
Solution Approach 2:
The patent applies different quality levels and encoding parameters to different spherical blocks based on their importance and visual characteristics. High-priority regions (e.g., areas corresponding to human face orientation) receive higher quality encoding, while less critical regions use more aggressive compression. This local quality approach improves overall compression efficiency while maintaining perceived video quality.
2Adaptability or versatility
If spherical geometry is used for 360-degree video, then the viewing experience is immersive, but the sampling density becomes uneven leading to distortion
Solution Approach 1:
The patent explicitly models the video content on a spherical geometry rather than a flat plane. The spherical blocks are arranged to conform to the sphere's curvature, and coordinate transformations are applied to map spherical coordinates to the display format. This maintains the immersive 360-degree viewing experience while accounting for the inherent curvature of the content.
Solution Approach 2:
The patent transforms the uneven spherical sampling into a more uniform representation by applying parameter changes during encoding. This includes repositioning and resampling techniques that adjust the density and distribution of sample points across the spherical surface, reducing distortion while preserving the immersive viewing experience.
3Measurement precision
If resolution is increased for better video quality, then viewer experience improves, but bandwidth requirements increase
Solution Approach 1:
The patent applies different resolution levels to different spherical blocks based on their visual importance and predicted viewer attention. Critical regions maintain high resolution, while less important areas use lower resolution. This selective quality approach reduces overall bandwidth consumption while preserving video quality in areas that matter most to the viewer experience.
Solution Approach 2:
The patent encodes only the necessary portions of the 360-degree video at full resolution, rather than encoding the entire sphere uniformly. By identifying and prioritizing specific regions (such as those likely to be in the viewer's field of view), the system achieves high perceived quality with reduced bandwidth requirements compared to uniform full-resolution encoding.
Data Source
AI summary
A coding device (e.g., that may be or may include encoder and/or decoder) may receive a frame-packed picture of 360-degree video. The coding device may identify a face in the frame-packed picture that the current block belongs to. The coding device may determine that a current block is located at a boundary of the face that the current block belongs to. The coding device may identify multiple spherical neighboring blocks of the current block. The coding device may identify a cross-face boundary neighboring block. The coding device may identify a block in the frame-packed picture that corresponds to the cross-face boundary neighboring block. The coding device may determine whether to use the identified block to code the current block based on availability of the identified block. The coding device may code the current block based on the determination to use the identified block.