Empirical study of user perception behavior for mobile streaming

The objective of this study is to examine the effect of individual factors over human perception behavior and to determine the right set of parameters which effectively exploit the underlying network and system capacity while maximizing the QoS perceived by the user. For the comprehensive test, we examine three different types of video clips: news, drama and sport game. From each of the original video clip, we vary the encoding factors as follows: playback rate(384Kbits/sec and 1.5 Mbits/sec), frame rate(5 frames/sec, 15 frames/sec, and 25 frames/sec) and spatial resolution(176x244 and 320x240). We performed extensive user experiment. We particularly focus on video streaming in mobile wireless environment where playback rate and screen size are relatively small. The analysis result reveals that out of three encoding factors, frame rate is the most influential factor. Spatial resolution does not make significant difference on QoS for three video categories. Playback rate results in noticeable difference in QoS. However, the analysis result suggests that the improvement on QoS obtained by quadrupling the playback rate (from 384Kbits/sec to 1.5 Mbits/sec) may not be justifiable particularly when the screen size is small.