Quality assessment for mobile media-enriched services: impact of video lengths

Abstract

The inclusion of multimedia content in different web-based services has increased significantly. Through an extensive subjective testing campaign, we analyse the quality of experience concerning video transmissions associated to these types of services when accessed from mobile devices and mobile Internet connections. Contrary to traditional normalised quality assessment studies, we point out the service context as a key aspect in quality assessments. Specifically, we analyse the impact of the duration of the test material on quality assessments. We find out that tolerance to visual degradations is higher in the specific context of use compared to when using standardised methodologies for quality assessment, which has a significant impact in terms of commercial service acceptability. Quality in web-based media-enriched servicesThe explosion of multimedia content on the Internet has attracted a number of commercial players. New media-enriched services are constantly being deployed on the web, such as mass media, online advertising in web pages, user interaction in social networks, user-generated content sharing portals, etc. At the same time, the segment of users who access these types of services through mobile connections is growing significantly.The quality of experience (QoE) as expressed by end users for these services is of paramount importance for service and network engineers, since it eventually influences customers' willingness to use the service. Although quality in video transmissions has been thoroughly studied in recent years, it has been commonly associated to visual quality [1,2] instead of addressing the problem from a pure service standpoint. Ibarrola proposes in [3] a general model for the management of quality of service (QoS) based on ITU-T E.802, where the concept of service is linked to the service context since it modifies both users' expectations and perceptions. Less work has been devoted to the study of multimedia services in their context of use. In [4] authors overview several studies concerning the key influence of the context in service quality evaluations: the upper and lower thresholds of satisfaction seem to be attenuated in the specific context of use. In [5], users are requested to watch full length movies with different types of degradations along the video track. Results show that the perceived visual quality is considerably different when compared to the traditional short duration tests. Additionally, users show different tolerance levels when movies are played at TV or PC screens, which points out that users' expectations play a major role in service evaluations.