An Adaptive Codec Switching Scheme for SIP-Based VoIP
Contemporary Voice-Over-IP (VoIP) systems typically negotiate only one codec for the entire VoIP session life time. However, as different codecs perform differently well under certain network conditions like delay, jitter or packet loss, this can lead to a reduction of quality if those conditions change during the call. This paper makes two core contributions: First, we compare the speech quality of a set of standard VoIP codecs given different network conditions. Second, we propose an adaptive end-to-end based codec switching scheme that fully conforms to the SIP standard. Our evaluation with a real-world prototype based on Linphone shows that our codec switching scheme adapts well to changing network conditions, improving overall speech quality.
KeywordsVoIP communication Codec Switching SIP
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- 1.Casetti, C., De Martin, J.C., Meo, M.: Framework for the analysis of adaptive voice over ip. In: 2000 IEEE International Conference on Communications, pp. 821–826 (June 2000)Google Scholar
- 2.ITU-T P.862: Perceptual evaluation of speech quality (pesq): An objective method for end-to-end speech quality assessment of narrow-band telephone networks and speech codecs (2001)Google Scholar
- 3.Linphone, http://www.linphone.org
- 4.Mazurczyk, W., Kotulski, Z.: Adaptive voip with audio watermarking for improved call quality and security. Journal of Information Assurance and Security 2(3), 226–234 (2007)Google Scholar
- 6.Ng, S.L., Hoh, S., Singh, D.: Effectiveness of adaptive codec switching voip application over heterogeneous networks. In: 2005 2nd International Conference on Mobile Technology, Applications and Systems, pages 7 (November 2005)Google Scholar
- 7.Pesq, http://www.pesq.org/
- 8.Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., Schooler, E.: SIP: Session Initiation Protocol. RFC 3261 (Proposed Standard) (June 2002); Updated by RFCs 3265, 3853, 4320, 4916, 5393, 5621, 5626, 5630, 5922, 5954, 6026, 6141Google Scholar
- 10.Testfile, http://www.itu.int/rec/T-REC-P.862-200511-I!Amd2Google Scholar
- 11.Wbest: a bandwidth estimation tool for IEEE 802.11 wireless networks, http://web.cs.wpi.edu/~claypool/papers/wbest/