Tradeoff Relationship between Fidelity and Latency in Interactive Audio-Video Applications over IP Networks

Yoshihiro ITO  Shuji TASAKA  

IEICE TRANSACTIONS on Communications   Vol.E90-B   No.5   pp.1112-1121
Publication Date: 2007/05/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e90-b.5.1112
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Network
user-level QoS assessment,  interactive audio-video application,  subjective tradeoff,  

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Interactive audio-video applications over IP networks have subjective tradeoffs between fidelity and latency owing to packet buffering at the receiver. Increasing the buffering time improves the fidelity, whereas it degrades the latency. This paper makes the subjective tradeoff between fidelity and latency clear in a quantitative way. In addition, we examine the effect of tasks on the subjective tradeoff. In evaluating the effect of tasks, we use two tasks according to ITU-T Recommendation P.920. An experiment was conducted to measure user-level QoS of an interactive application with the psychometric methods. We then investigate the subjective tradeoff quantitatively by QoS mapping. The experimental results confirm that there exists the buffering time which makes user-level QoS the highest. The results also show that the optimum buffering time depends on the kind of task.