Omnidirectional or 360-degree videos are considered as a next step towards a truly immersive media experience. Such videos allow the user to change her/his viewing direction while consuming the video. The download-and-play paradigm (including DVD and Blu-ray) is replaced by streaming, and the content is hosted solely within the cloud. This paper addresses the need for a scientific framework enabling the adaptive delivery of omnidirectional video within heterogeneous environments. We consider the state-of-the-art techniques for adaptive streaming over HTTP and extend them towards omnidirectional/360-degree videos. In particular, we review the encoding and adaptive streaming options, and present preliminary results reported in the literature. Finally, we provide an overview about the ongoing standardization efforts and highlight the major open issues.
In this study, we investigate a VR simulator of a forestry crane used for loading logs onto a truck, mainly looking at Quality of Experience (QoE) aspects that may be relevant for task completion, but also whether there are any discomfort related symptoms experienced during task execution. The QoE test has been designed to capture both the general subjective experience of using the simulator and to study task completion rate. Moreover, a specific focus has been to study the effects of latency on the subjective experience, with regards both to delays in the crane control interface as well as lag in the visual scene rendering in the head mounted display (HMD). Two larger formal subjective studies have been performed: one with the VR-system as it is and one where we have added controlled delay to the display update and to the joystick signals. The baseline study shows that most people are more or less happy with the VR-system and that it does not have strong effects on any symptoms as listed in the Simulator Sickness Questionnaire (SSQ). In the delay study we found significant effects on Comfort Quality and Immersion Quality for higher Display delay (30 ms), but very small impact of joystick delay. Furthermore, the Display delay had strong influence on the symptoms in the SSQ, and causing test subjects to decide not to continue with the complete experiments. We found that this was especially connected to the longer added Display delays (≥ 20 ms).
In this work, we present the results of a psycho-physical experiment in which a group of volunteers rated the quality of a set of audio-visual sequences. The sequences had up to three types of distortions: video coding, packet-loss, and frame freezing distortions. The original content used for the experiment consisted of a set of high definition audio-visual sequences. Impairments were only inserted into the video component of the sequences, while the audio component remained unimpaired. The objective of this particular experiment was to analyze different types of source degradations and compare the transmission scenarios where they occur. Given the nature of these degradations, the analysis is focused on the visual component of the sequence. The experiment was conducted using the basic directions of the immersive experimental methodology.