Viewport Adaptive Streaming for Omnidirectional Video Delivery

07/20/2020

In this thesis, the offset cubemap projection (OCM) – a Viewport Adaptive Streaming (VAS) strategy developed by Oculus – is optimized to provide an enhanced omnidirectional video VAS. The OCM projection allows higher spatial resolution (thus, higher quality) around a predefined direction of the omnidirectional video – the offset orientation – by distorting spherical angles. The Oculus implementation of the OCM streaming considers a fix offset magnitude of 0.7, which was proven (in this thesis) to not provide the optimal viewport quality. 11 offset values were objectively evaluated using three omnidirectional videos, having distinct spatial-temporal activities. The best offset magnitude value was found to be 0.42, allowing quality gains (measured using the V-PSNR metric) of up to 2.3 dB, relatively to an offset magnitude of 0.7. The assessment of the optimized OCM projection, for VAS, was then conducted considering several state-of-the-art streaming strategies as benchmarks; these were of two types: the monolithic strategies and tiles-based strategies. For static viewports, OCM based video streaming achieved better results than the benchmarks,either when the requested (to the server) viewport center orientation matched the viewing direction, either when an error of up to 20° between these two directions was introduced. Using previously recorded head trajectories from real users, the OCM based streaming provided better viewport quality than the conventional monolithic streaming, and competed with the considered tiled based streaming strategies.

Authors in the community:

• 

  M

  Miguel Mateus D'Avó Luís

  ist181632

Supervisors of this institution:

• 

  J

  João Miguel Duarte Ascenso

  ist31104

• 

  M

  Maria Paula Dos Santos Queluz

  ist12401

mechanical-engineering - Mechanical engineering

por - Portuguese

Instituto Superior Técnico