and 252 ppi pixel density, 1GHz CPU and 576MB RAM.
A. User Study Three representative video types were chosen. The first type consisted of sports videos of NFL American football games and German Bundesliga soccer games. The second type consisted of talks from TED conferences [19]. And the third type consisted of documentary films. We analyzed the effect of zooming, the effect of segment based and tag based browsing on mobile user experience. To compare the different tasks during the user study of user experience of MVCS, the NASA Task Load Index (NASA- TLX) questionnaire [20] was used. NASA-TLX is usually used to assess the workload on users working with different human- machine systems, in our case the mobile client of MVCS. It is a multi-dimensional rating procedure which derives an overall workload score on the basis of weighted average of ratings on six subscales. The subscales are Mental Demands, Physical Demands, Temporal Demands, Own Performance, Effort and Frustration. Scales like Frustration, Mental Demands are very important for the mobile client of MVCS as searching certain scenes can be mentally demanding and frustrating. We used NASA-TLX to compare the standard video player on Android device with video browsing and zooming enabled player of MVCS. Twelve persons participated in the evaluation of mobile user experience. The participants were between 23 and 54 years old. They had mixed smartphone usage background, ranging from individuals who didn’t posses a smartphone to who watched YouTube video on their devices everyday. Each user had to watch each video twice. The first time with zooming enabled and the second time without zooming. The order of playing is changed for every user, in order to minimize the influences of the playing order for the overall results. After each video, the user filled in the NASA TLX Index rating scale after each video playback and weighted the scales after watching all videos. The same procedure was repeated for the segment and tag based browsing. However, in the tasks in these cases were extended to to find two certain scenes in a video with both the native mobile player and with the MVCS player.