Psychometric analysis of the effect of end-to-end delay on user-level QoS in live audio-video transmission

This paper investigates the effect of the mean and jitter of end-to-end delay on use-level QoS of live audio-video transmission. The temporal structure of continuous media can be disturbed by the delay jitter of packets. The temporal disturbance causes a subjective degradation of the media. On the other hand, long end-to-end delay also degrades the 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 the packets of live audio and video according to the 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.