PlanetLab: an overlay testbed for broad-coverage services
ACM SIGCOMM Computer Communication Review
Revealing skype traffic: when randomness plays with you
Proceedings of the 2007 conference on Applications, technologies, architectures, and protocols for computer communications
Analysis of Skype VoIP traffic in UMTS: End-to-end QoS and QoE measurements
Computer Networks: The International Journal of Computer and Telecommunications Networking
Skype video responsiveness to bandwidth variations
Proceedings of the 18th International Workshop on Network and Operating Systems Support for Digital Audio and Video
Measuring Interaction QoE in Internet Videoconferencing
MMNS '07 Proceedings of the 10th IFIP/IEEE International Conference on Management of Multimedia and Mobile Networks and Services: Real-Time Mobile Multimedia Services
Analyzing Voice Quality in Popular VoIP Applications
IEEE MultiMedia
Detailed analysis of Skype traffic
IEEE Transactions on Multimedia
Statistical scheduling of offline comparative subjective evaluations for real-time multimedia
IEEE Transactions on Multimedia - Special issue on quality-driven cross-layer design for multimedia communications
Performance of Video-Chat Applications under Congestion
ISM '09 Proceedings of the 2009 11th IEEE International Symposium on Multimedia
IEEE Network: The Magazine of Global Internetworking - Special issue on improving quality of experience for network services
Mobile JND: environment adapted perceptual model and mobile video quality enhancement
Proceedings of the 3rd Multimedia Systems Conference
Measurement study of multi-party video conferencing
NETWORKING'10 Proceedings of the 9th IFIP TC 6 international conference on Networking
Standardization activities in the ITU for a QoE assessment of IPTV
IEEE Communications Magazine
Estimating Just-Noticeable Distortion for Video
IEEE Transactions on Circuits and Systems for Video Technology
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This paper proposes a novel approach for improving the quality of experience (QoE) of real-time video conferencing systems. In these systems, QoE is affected by signal quality as well as interactivity, both depending on the packet loss rate, delay jitters, and mouth-to-ear delay (MED) that measures the sender-receiver delay on audio signals (and will be the same as that of video signals when video and audio is synchronized). We notice in the current Internet that increasing MED as well as reducing packet rate can help reduce the delay-aware loss rate in congested connections. Between the two methods, the former plays a more important role and applies well to a variety of network conditions for improving audiovisual signal quality, although overly increasing the MED will degrade interactivity. Based on a psychophysical concept called just-noticeable difference (JND), we find the extent to which MED can be increased, without humans perceiving the difference from the original conversation. The approach can be applied to improve existing video conferencing systems. Starting from the operating point of an existing system, we increase its MED to within JND in order to have more room for smoothing network delay spikes as well as recovering lost packets, without incurring noticeable degradation in interactivity. We demonstrate the idea on Skype and Windows Live Messenger by designing a traffic interceptor to extend their buffering time and to perform packet scheduling/recovery. Our experimental results show significant improvements in QoE, with much better signal quality while maintaining similar interactivity.