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Assessing the Transmission of VoIP Packets

This web page contains contributions, on how to rate the service quality of VoIP systems. The contributions consists of publications, software and measurement data:

Predicting the Perceptual Service Quality Using a Trace of VoIP Packets

Christian Hoene, Holger Karl, Adam Wolisz

Abstract
On this web page we present an instrumental approach on how to assess the perceptual quality of voice transmissions in IP-based communication networks. Our approach is end-to-end and uses combinations of common codecs, loss concealment algorithms, playout schedulers, and ITU's quality assessment algorithms E-Model and PESQ. It is the first method that takes into account the impact of playout rescheduling and non-random packet loss distributions. Non-random packet losses occur if a rate-distortion optimized multimedia streaming algorithm forwards packets dependent on the packets' importance. We provide an open-source software package in which our approach is implemented. It evaluates both experimental and simulated VoIP systems. It includes various playout schedulers for Voice over IP (VoIP) described by Schulrzinne, Ramjee, Moon, Lin and others. Also, the two most common speech encoding schemes (G.711 and G.729) are supported. Finally, two quality models (ITU's PESQ and E-Model) predict the perceptual end-to-end transmission quality.
Keywords
VoIP, quality assessment, playout scheduling, rate-distortion optimized streaming
Publications
  • C. Hoene, S. Wiethölter, and A. Wolisz, "Predicting the Perceptual Service Quality Using a Trace of VoIP Packets", In Proceedings of Fifth International Workshop on Quality of future Internet Services (QofIS'04), Barcelona, Spain, September 2004. (PDF (PDF, 637,0 KB))
  • C. Hoene, H. Karl, and A. Wolisz, "A Perceptual Quality Model for Adaptive VoIP Applications", In Proceedings of International Symposium on Performance Evaluation of Computer and Telecommunication Systems (SPECTS'04), San Jose, California, USA, July 2004, Paper won the Best Paper Award of the conference. (PDF (PDF, 591,0 KB))
  • C. Hoene and E. Dulamsuren-Lalla, "Predicting Performance of PESQ in Case of Single Frame Losses", In Proc. MESAQIN 2004, Prague, CZ, June 2004 MESAQIN 2004 - Measurement of Speech and Audio Quality in Networks, (Slides). (PDF (PDF, 446,0 KB))
 
Software
Version 2 (September 27th, 2004): Source Code (BZ2, 1,2 MB) Manual (PDF, 224,7 KB)

A Perceptual Quality Model for Adaptive VoIP Applications

Christian Hoene, Holger Karl, Adam Wolisz

Abstract
Quality models predict the perceptual quality of services as they calculate subjective ratings from measured parameters. In this paper we present a new quality model that evaluates VoIP telephone calls in order to control their transmission at run-time. In addition to packet loss rate, coding mode and delay it takes into account the impairments due to change in the transmission configuration (e.g. switching the coding mode or re-scheduling the playout time). It is also computation efficient and open source. To demonstrate its potential, we apply our model to select the ideal coding and packet rate in bandwidth-limited environments. Furthermore we decide, based on model predictions, whether to delay the playout of speech frames after delay spikes. Delay spikes often occur after congestion and cause packets to arrive too late. We show a considerable improvement in perceptual speech quality.
Keywords
Internet telephony, adaptive VoIP, perceptual quality model, E-model, PESQ, packetization, delay spikes.
Publication
  • C. Hoene, H. Karl, and A. Wolisz, "A Perceptual Quality Model for Adaptive VoIP Applications", In Proceedings of International Symposium on Performance Evaluation of Computer and Telecommunication Systems (SPECTS'04), San Jose, California, USA, July 2004, Paper won the Best Paper Award of the conference. (PDF (PDF, 591,0 KB))
Download
The software distribution can be downloaded here (release V1, August 17th, 2004 (ZIP, 7,1 MB)).

Listening-Only Test Results for Non-random Packet Losses and Playout Rescheduling

Tuya Dulamsuren-Lalla, Lana Abdelkarim and Christian Hoene

Abstract
ITU's objective evaluation algorithm PESQ predicts the quality of speech transmissions. In this listening-only tests we have verify whether PESQ can measure the impact of single frame losses and playout rescheduling -- sources of impairment for which PESQ has not been designed or verified.
This web site contains the artifically constructed audio samples used for the listening-only tests and the MOS results from from humans and PESQ. We provide these results to other researchers in order to allow enhancements of quality assessment algorithms.
Publications
  • C. Hoene, S. Wiethölter, and A. Wolisz, "Predicting the Perceptual Service Quality Using a Trace of VoIP Packets", In Proceedings of Fifth International Workshop on Quality of future Internet Services (QofIS'04), Barcelona, Spain, September 2004. (PDF (PDF, 637,0 KB))
  • C. Hoene and E. Dulamsuren-Lalla, "Predicting Performance of PESQ in Case of Single Frame Losses", In Proc. MESAQIN 2004, Prague, CZ, June 2004 MESAQIN 2004 - Measurement of Speech and Audio Quality in Networks, (Slides). (PDF (PDF, 446,0 KB))
Software
Laboratory Data (Version 1 from August 17th, 2004; Size 41Mbyte (ZIP, 41,1 MB))

Mongolia: An Auditory Testing Environment to Study the Importance of a VoIP Packet

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