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

Optimum Encoding Approaches on Video Resolution Changes: A Comparative Study

Video resolution changes in an HTTP adaptive streaming session may negatively affect the viewer's quality of experience. Our goal is, through encoding, to make such resolution changes less noticeable for the viewers. This can be achieved by taking video complexity features into account during the encoding process. In this paper, we compare Constant Bitrate (CBR) versus Constrained Constant Rate Factor (CRF) coding approaches and their effects on the noticeability of video resolution changes. To this end, we conducted a dedicated subjective study with 20 subjects in a quasi -lab environment. Our results suggest that choices for fixed-bitrate encoding have to be improved by deeper analysis of video complexity and resolution change patterns.European Union in the context of Horizon 2020 Research and Innovation Programme under Marie Sklodowska-Curie Innovative Training Networks (MSCA-ITN-2014-ETN