Designing Real-time, Continuous QoE Score Acquisition Techniques for HMD-based 360°VR Video Watching

Watching HMD-based 360° video has become in-creasing popular as a medium for immersive viewing of photo-realistic content. To evaluate subjective video quality, researchers typically prompt users to provide an overall Quality of Experience (QoE) score after viewing a stimulus. However, since users can adjust their viewport throughout a 360° video, a higher level of spatiotemporal granularity is needed for adaptive 360° video streaming. To address this, we design several real-time, continuous QoE annotation input and peripheral visualization techniques, with the goal of minimizing mental workload and distraction during score acquisition. Drawing on two parallel co-design sessions with seven experts, we find that touchpad and joystick are most suitable for continuous input, with DotMorph (circle with tick label that varies in filling) for peripheral state feedback. We contribute design findings for testing QoE score acquisition techniques during HMD-based 360° video watching, which enable more precise optimization of adaptive video streaming quality.