Combined Projection Format for 360-Degree Video Bandwidth Optimization
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Solution Overview
Problem
Current 360-degree video projection formats, such as equirectangular and equal area projections, face challenges in balancing viewport quality and memory bandwidth consumption, particularly around the North and South poles, where peak memory bandwidth consumption is high and unbalanced with EAP, and quality is compromised with ERP.
Innovation Solution
A combined projection format (CEP) is introduced, which integrates characteristics of ERP and EAP, using control parameters α and β to control resampling resolution in both horizontal and vertical directions, allowing for better trade-offs between viewport quality and memory bandwidth consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If equirectangular projection (ERP) is used, then viewport quality is maintained, but memory bandwidth consumption becomes unbalanced with high peaks around North and South poles
Solution Approach 1:
The patent applies local quality by using Equal Area Projection (EAP) specifically around the North and South poles where ERP causes excessive memory bandwidth consumption, while maintaining ERP in other regions where it provides adequate viewport quality. This localized switching resolves the contradiction by optimizing each region's projection method according to its specific requirements.
Solution Approach 2:
The patent implements a dynamic projection format that can switch between ERP and EAP based on the viewing direction and pole proximity. The system dynamically determines which projection format to use for rendering different portions of the 360-degree video, allowing adaptive optimization of both viewport quality and memory bandwidth consumption throughout the playback.
2Use of energy by moving object
If equal area projection (EAP) is used, then memory bandwidth consumption is reduced, but viewport quality around poles deteriorates
Solution Approach 1:
The patent applies local quality by using Equal Area Projection (EAP) specifically around the North and South poles where ERP causes excessive memory bandwidth consumption, while maintaining ERP in other regions where it provides adequate viewport quality. This localized switching resolves the contradiction by optimizing each region's projection method according to its specific requirements.
3Device complexity
If a single projection format is used for entire 360-degree video, then system complexity is reduced, but cannot simultaneously optimize both compression efficiency and viewport quality across all regions
Solution Approach 1:
The patent implements a dynamic projection format that can switch between ERP and EAP based on the viewing direction and pole proximity. The system dynamically determines which projection format to use for rendering different portions of the 360-degree video, allowing adaptive optimization of both viewport quality and memory bandwidth consumption throughout the playback.
Solution Approach 2:
The patent creates a universal combined projection format system that can handle both ERP and EAP within a single rendering pipeline. This multi-functional system processes different projection formats through unified decoding and rendering operations, managing complexity while enabling region-specific optimization for compression efficiency and quality.
Data Source
AI summary
In a system for 360 degree video capture and playback, 360 degree video may be captured, stitched, encoded, decoded, rendered, and played-back. A device for video coding with adaptive projection format may include at least one processor configured to combine at least two different projection formats into a combined projection format and encode a video stream using the combined projection format. The at least one processor may be further configured to decode a video stream that is encoded with a combined projection formation that includes at least two different projection formats.