Psychometric Analysis of the Effect of End-to-End Delay on User-Level QoS in Live Audio-Video Transmission

摘要

This paper investigates the effect of the mean and jitter of end-to-end delay on user-level QoS of live audio-video transmission. The temporal structure of continuous media can be disturbed by delay jitter of packets. The temporal disturbance causes subjective degradation of the media. On the other hand, long end-to-end delay also degrades quality of live media subjectively. Therefore, it is necessary to study the effect of the mean delay and the delay jitter on user-level QoS degradation. In this paper, we assess the effect by experiment and a psychometric method. In our experiment, we actually delay packets of live audio and video according to Pareto-normal distribution with a network emulator and assess user-level QoS of the live transmission with the method of successive categories, which is a psychometric method. As a result, we show that the standard deviation of delay is more dominant than the mean delay in the effect on the user-level QoS. We also perform QoS mapping from application-level to user-level with multiple regression analysis. From the QoS mapping, we clarify the effect of degradation of the application-level QoS caused by the mean and standard deviation of delay on the user-level QoS.