IMPACT OF VIDEO RESOLUTION CHANGES ON QoE FOR ADAPTIVE VIDEO STREAMING

HTTP adaptive streaming (HAS) has become the de-facto standard for video streaming to ensure continuous multimedia service delivery under irregularly changing network conditions. Many studies already investigated the detrimental impact of various playback characteristics on the Quality of Experience of end users, such as initial loading, stalling or quality variations. However, dedicated studies tackling the impact of resolution adaptation are still missing. This paper presents the results of an immersive audiovisual quality assessment test comprising 84 test sequences from four different video content types, emulated with an HAS adaptation mechanism. We employed a novel approach based on systematic creation of adaptivity conditions which were assigned to source sequences based on their spatio-temporal characteristics. Our experiment investigates the resolution switch effect with respect to the degradations in MOS for certain adaptation patterns. We further demonstrate that the content type and resolution change patterns have a significant impact on the perception of resolution changes. These findings will help develop better QoE models and adaptation mechanisms for HAS systems in the future

Affective Adaptation of Social Norms in Workplace Design

Open-plan offices are common in today's organisations. These types of workplaces require people to share a common space, where violation of (implicitly or explicitly stated) social norms can cause instances of incivility. If nothing is done to avoid these situations, bad feeling can lead to diminished productivity and cooperation, and, in the long-term, to more serious problems, such as conflict and aggression. A critical review of literature shows the effects of workplace incivility and the need for an internal reparation mechanism. Inspired by convergence of pervasive, adaptive and affective computing, we have designed and developed a self-regulatory platform for successful collective action, based on participatory adaptation and fair information practises, which we called MACS. MACS addresses the problem of incivility and aims at improving the Quality of Experience in shared workplaces. This thesis presents all studies that led to the development of MACS. Through the analysis of an online questionnaire we gathered information about incivility in shared workplaces, how people deal with those situations, and awareness about uncivil self-behaviours. We concluded the main issue while sharing a workplace is noise, and most people will try to change their own behaviour, rather than confronting the person being uncivil. MACS's avatar-based interface was developed with the purpose of heightening self-awareness and cueing the appropriate social norms, while providing a good User Experience (UX). Avatars created to people's image, rather than photos, were used, to keep MACS's tone light and relatively unintrusive, while still creating self-awareness. MACS's final version went through UX testing, where 6 people were filmed while performing tasks in MACS. The intended work-flow and user interfaces to support the smooth passage of the work-flow have been validated by the UX user testing. There is some preliminary evidence suggesting apology will elicit empathic responses in MACS. Finally, this thesis proposes guidelines for workplace design, which are founded on participatory creation and change of social norms, and ways to make sure they are enforced. In this sense, MACS can also be seen as a prototypical example of a socio-technical system being used as platform for successful collective action.Open Acces