M. Combining and C. Sfu, Spare cloud video conferencing provider resources in terms of CPU cycles and network bandwidth consumption -Significantly reduce end-to-end delay, improving end user QoE Figure 4.7: Structure of DGC system integrated with Cloud The idea is the following: we combine before mentioned techniques and obtain four possible approaches to video conferencing. Signaling server can be in Cloud or onpremises . We are talking here only about media server and media flows. SFU in Fog: '+': No Cloud CPU utilization '+': No WAN utilization '+': No additional decoding/encoding MCU in Fog: '+': No Cloud CPU utilization '+': No WAN utilization, Moderate Cloud CPU utilization References

J. Zeng, O. C. Au, W. Dai, Y. Kong, L. Jia et al., A tutorial on image/video coding standards, 2013 Asia-Pacific Signal and Information Processing Association Annual Summit and Conference, 2013.
DOI : 10.1109/APSIPA.2013.6694346

, Advanced video coding for generic audiovisual services, 2003.

G. Annex and . Itu-t, Advanced video coding for generic audiovisual services, 2007.

, H.265 : High efficiency video coding, 2013.

J. Bankoski, J. Koleszar, L. Quillio, J. Salonen, P. Wilkins et al., VP8 Data Format and Decoding Guide, 2011.

J. Uberti, S. Holmer, M. Flodman, J. Lennox, and D. Hong, RTP Payload Format for VP9 Video, IETF Work in Progress, 2016.

A. Fuldseth, G. Bjontegaard, S. Midtskogen, T. Davies, and M. Zanaty, IETF Work in Progress, 2016.

H. Schulzrinne, S. Casner, R. Frederick, and V. Jacobson, RTP: A Transport Protocol for Real-Time Applications, 2003.
DOI : 10.17487/rfc3550

J. Rosenberg, H. Schulzrinne, G. Camarillo, A. Johnston, J. Peterson et al., SIP: Session Initiation Protocol, 2002.
DOI : 10.17487/rfc3261

, H.323 : Packet-based multimedia communications systems, 1996.

S. Ludwig, P. Saint-andre, S. Egan, R. Mcqueen, and D. Cionoiu, XEP-0167: Jingle RTP Sessions, 2009.

E. Burger, J. Van-dyke, and A. Spitzer, Basic Network Media Services with SIP, IETF RFC, vol.4240, 2005.
DOI : 10.17487/rfc4240

J. Rosenberg, A Framework for Conferencing with the Session Initiation Protocol (SIP), 2006.
DOI : 10.17487/rfc4353

A. Saleem, Y. Xin, and G. Sharratt, Media Server Markup Language (MSML) " , IETF RFC 5707, 2010.

J. Van-dyke, E. Burger, and A. Spitzer, Media Server Control Markup Language (MSCML) and Protocol, 2006.

M. Barnes, C. Boulton, and O. Levin, A Framework for Centralized Conferencing, 2008.
DOI : 10.17487/rfc5239

, An Architectural Framework for Media Server Control, IETF RFC, vol.5567, 2009.

, JSR 309: Media Server Control API, 2009.

R. Presta and S. Romano, IETF Work in Progress, 2016.

M. Baugher, D. Mcgrew, M. Naslund, E. Carrara, and K. Norrman, The Secure Real-time Transport Protocol (SRTP), 2004.
DOI : 10.17487/rfc3711

P. Zimmermann, A. Johnston, and J. Callas, ZRTP: Media Path Key Agreement for Unicast Secure RTP, 2011.
DOI : 10.17487/rfc6189

J. Arkko, E. Carrara, F. Lindholm, M. Naslund, and K. Norrman, MIKEY: Multimedia Internet KEYing, 2004.

F. Andreasen, M. Baugher, and D. Wing, Session Description Protocol (SDP) Security Descriptions for Media Streams, 2006.
DOI : 10.17487/rfc4568

D. Mcgrew and E. Rescorla, Datagram Transport Layer Security (DTLS) Extension to Establish Keys for the Secure Real-time Transport Protocol (SRTP), 2010.
DOI : 10.17487/rfc5764

J. Rosenberg, R. Mahy, P. Matthews, and D. Wing, Session Traversal Utilities for NAT (STUN), p.5389, 2008.
DOI : 10.17487/rfc5389

R. Mahy, P. Matthews, and J. Rosenberg, Traversal Using Relays around NAT (TURN): Relay Extensions to Session Traversal Utilities for NAT (STUN), 2010.
DOI : 10.17487/rfc5766

URL : https://www.rfc-editor.org/rfc/pdfrfc/rfc5766.txt.pdf

J. Rosenberg, Interactive Connectivity Establishment (ICE): A Protocol for Network Address Translator (NAT) Traversal for Offer/Answer Protocols, 2010.
DOI : 10.17487/rfc5245

URL : http://www.hakusan.tsg.ne.jp/%7Etjkawa/www.ietf.org/rfc/pdf/rfc5245.txt.pdf

M. Westerlund and S. Wenger, IETF RFC, vol.7667, 2015.

F. Kuipers, R. Kooij, D. D. Vleeschauwer, and K. Brunnström, Techniques for Measuring Quality of Experience, 8th International Conference WWIC 2010, 2010.
DOI : 10.1007/978-3-642-13315-2_18

, The NIST Definition of Cloud Computing " , National Institute of Standards and Technology, 2011.

C. Holmberg, S. Hakansson, and G. Eriksson, Web Real-Time Communication Use Cases and Requirements, IETF RFC 7478, 2015.
DOI : 10.17487/rfc7478

URL : https://www.rfc-editor.org/rfc/pdfrfc/rfc7478.txt.pdf

L. M. Vaquero and L. Rodero-merino, Finding your Way in the Fog, ACM SIGCOMM Computer Communication Review, vol.44, issue.5, 2014.
DOI : 10.1145/2677046.2677052

D. Kondo, M. Taufer, C. Brooks, H. Casanova, and A. Chien, Characterizing and evaluating desktop grids: an empirical study, 18th International Parallel and Distributed Processing Symposium, 2004. Proceedings., 2004.
DOI : 10.1109/IPDPS.2004.1302936

G. Novelli, G. Pappalardo, C. Santoro, and E. Tramontana, A grid-based infrastructure to support multimedia content distribution, Proceedings of the second workshop on Use of P2P, GRID and agents for the development of content networks , UPGRADE '07, pp.57-64, 2007.
DOI : 10.1145/1272980.1272983

S. Chakraborty and C. H. Yen, A Simulation Based Comparative Study of Normalization Procedures in Multiattribute Decision Making, Proceedings of the 6th WSEAS Int, pp.102-109, 2007.

K. Yoon and C. L. Hwang, Multiple Attribute Decision Making Introduction, 1995.

A. Alalousi, A. Osman, S. Noori, A. Hussain, A. Munther et al., A Study on Video Conferencing using Overlay Network, European Journal of Scientific Research, vol.59, issue.3, 2011.

M. Chen, M. Ponec, S. Sengupta, J. Li, and P. Chou, Utility Maximization in Peerto-Peer Systems With Applications to Video Conferencing, IEEE/ACM ToN, vol.20, issue.6, 2012.
DOI : 10.1109/tnet.2012.2201166

X. Yu and Z. Yu, A Distributed Architecture of Video Conference Using P2P Technology, Journal of Networks, vol.7, issue.11, 2012.
DOI : 10.4304/jnw.7.11.1852-1859

A. Munther, S. Noori, A. Osman, A. Hussain, I. Jasim et al., Peer-to- Peer Video Conferencing Using Hybrid Content Distribution Model, Journal of Computer Science, vol.8, issue.7, p.2012

". G. , One-way transmission time, 2003.

, P.910 : Subjective video quality assessment methods for multimedia applications, 2008.

R. Pastrana and . Vidal, Sporadic frame dropping impact on quality perception, Human Vision and Electronic Imaging IX, 2004.
DOI : 10.1117/12.525746

R. Pastrana-vidal and J. Gicquel, Looking at the relationship between video bitrates and end-user quality assessment: subjective tests approach, ETSI Workshop Effect of transmission performance on Multimedia Quality Service, 2008.

I. Bt, SAMVIQ ? Subjective Assessment Methodology for Video Quality, 1788.

A. Azzazi, H. Abusaimeh, and S. R. Masadeh, CPU Utilization for a Multiple Video Streaming Over a Fiber Optic ATM-Network when Varying the Quality of Service, Journal of Emerging Trends in Computing and Information Sciences, vol.5, issue.3, 2014.

M. Goudarzi, L. Sun, and E. Ifeachor, Impact of Bursty Packet Loss on Voice and Video Quality in Wireless Networks, Postgraduate Conference for Computing: Applications and Theory (PCCAT), 2010.

A. Tarakanov, O. Gushchina, and I. Nenakhov, Influence of packets losses on video quality in case of using multiple description coding with time division into two and three substreams, 2015 17th Conference of Open Innovations Association (FRUCT), 2015.
DOI : 10.1109/FRUCT.2015.7117998

S. Murphy, M. Searles, C. Rambeau, and L. Murphy, Evaluating the Impact of Network Performance on Video Streaming Quality for Categorised Video Content, 14th International Packet Video Workshop, 2004.

A. Kwon, J. Xiao, S. Seo, R. Hong, and . Boutaba, The Impact of Network Performance on Perceived Video Quality in H, 2012 IEEE Network Operations and Management Symposium, p.2012

M. Claypool and J. Tanner, The Effects of Jitter on the Perceptual Quality of Video, ACM Multimedia, vol.2, 1999.

A. Khan, L. Sun, and E. Ifeachor, Impact of Video Content on Video Quality for Video over Wireless Networks, 2009 Fifth International Conference on Autonomic and Autonomous Systems, 2009.
DOI : 10.1109/ICAS.2009.23

R. Alimi, R. Penno, and Y. Yang, Application-Layer Traffic Optimization (ALTO) Protocol, 2014.
DOI : 10.17487/rfc7285

T. S. Ng and H. Zhang, Predicting Internet network distance with coordinates-based approaches, Proceedings.Twenty-First Annual Joint Conference of the IEEE Computer and Communications Societies, p.2, 2002.
DOI : 10.1109/INFCOM.2002.1019258

URL : http://www-2.cs.cmu.edu/~eugeneng/papers/INFOCOM02.ps.gz

F. Dabek, R. Cox, F. Kaashoek, and R. Morris, Vivaldi: A Decentralized Network Coordinate System, ACM SIGCOMM, 2004.

M. Costa, M. Castro, R. Rowstron, and P. Key, PIC: practical Internet coordinates for distance estimation, 24th International Conference on Distributed Computing Systems, 2004. Proceedings., 2004.
DOI : 10.1109/ICDCS.2004.1281582

URL : http://www.cl.cam.ac.uk/Teaching/2003/AdvSysTop/pic.pdf

V. Ramasubramanian, D. Malkhi, F. Kuhn, I. Abraham, M. Balakrishnan et al., A Unified Network " Coordinate " System for Bandwidth and Latency, 2008.

H. Lim, J. C. Hou, and C. Choi, Constructing internet coordinate system based on delay measurement, Proceedings of the 2003 ACM SIGCOMM conference on Internet measurement , IMC '03, 2003.
DOI : 10.1145/948205.948222

Y. Chen, Y. Xiong, X. Shi, J. Zhu, B. Deng et al., Pharos: accurate and decentralised network coordinate system, IET Communications, vol.3, issue.4, 2009.
DOI : 10.1049/iet-com.2008.0187

P. Francis, S. Jamin, C. Jin, Y. Jin, D. Raz et al., IDMaps: a global Internet host distance estimation service, IEEE/ACM Transactions on Networking, vol.9, issue.5, 2001.
DOI : 10.1109/90.958323

URL : http://www.stanford.edu/class/cs244b/pdf/idmaps-ton.pdf

B. Wong, A. Slivkins, and E. G. Sirer, Meridian: A Lightweight Network Location Service without Virtual Coordinates, ACM SIGCOMM, vol.35, issue.4, 2005.

M. J. Freedman, K. Lakshminarayanan, and D. Mazières, OASIS: Anycast for Any Service, NSDI'06 Proceedings of the 3rd conference on Networked Systems Design & Implementation, 2006.

L. Chao, Z. Miao, and L. Yong, Optimal Bandwidth Sharing in Multiswarm Multiparty P2P Video-Conferencing Systems, IEEE/ACM Transactions On Networking, vol.19, issue.6, 2011.

T. Ruso, C. Prabhu, and C. Chellappan, Netrawalm: Network Based Resource Aware Application Layer Multicast For Multiparty Video Conference, International Journal of Distributed and Parallel systems, vol.2, issue.5, 2011.
DOI : 10.5121/ijdps.2011.2503

URL : https://doi.org/10.5121/ijdps.2011.2503

E. Karrupiah, E. Lin, T. Phan, N. Thoai, E. Muramoto et al., Bandwidth Fair Application Layer Multicast for Multi-Party Video Conference Application, Consumer Communications and Networking Conference, 2009.

A. Abbasi and T. Mehmood, Dynamic Scalable Model for Video Conferencing (DSMVC) using Request Routing, International Journal of Video & Image Processing and Network Security, vol.9, issue.9, 2009.

X. Wu, K. Dhara, and V. Krishnaswamy, Enhancing Application-Layer Multicast for P2P Conferencing, 2007 4th IEEE Consumer Communications and Networking Conference, 2007.
DOI : 10.1109/CCNC.2007.199

P. Yuen and G. Chan, MixNStream, Proceedings of the 2010 ACM workshop on Advanced video streaming techniques for peer-to-peer networks and social networking, AVSTP2P '10, 2010.
DOI : 10.1145/1877891.1877909

W. Ooi and R. Renesse, Distributing media transformation over multiple media gateways, Proceedings of the ninth ACM international conference on Multimedia , MULTIMEDIA '01, 2001.
DOI : 10.1145/500141.500166

URL : http://www.bmrc.berkeley.edu/~weitsang/papers/dist-acmmm01-final.ps.gz

D. Maggiorini and D. Riboni, Continuous Media Adaptation for Mobile Computing Using Coarse-Grained Asynchronous Notifications, 2005 Symposium on Applications and the Internet Workshops (SAINT 2005 Workshops), 2005.
DOI : 10.1109/SAINTW.2005.1620002

URL : http://homes.dico.unimi.it/~riboni/saint05.pdf

S. E. Restrepo, P. Pinaud, J. E. Pezoa, and S. Sobarzo, Energy-aware image allocation for distributed video processing on handheld devices, 2013 IEEE 32nd International Performance Computing and Communications Conference (IPCCC), 2013.
DOI : 10.1109/PCCC.2013.6742761

S. Mohapatra, R. Cornea, N. Dutt, A. Nicolau, and N. Venkatasubramanian, Integrated power management for video streaming to mobile handheld devices, Proceedings of the eleventh ACM international conference on Multimedia , MULTIMEDIA '03, 2003.
DOI : 10.1145/957013.957134

URL : http://webfiles.uci.edu/smohapat/pub/mohapatra03acmmm.pdf

R. Lienhart, I. Kozintsev, Y. Chen, M. Holliman, M. Yeung et al., Challenges in Distributed Video Management and Delivery, Handbook of Video Databases Design and Applications, 2003.

M. Kim, Y. Cui, H. Lee, and H. Lee, Performance Evaluation of a Hadoop-based Distributed Video Transcoding System for Mobile Media Service, Proceedings of IST 2012 International Conference, 2012.

M. Hossain and J. Khan, Dynamic MCU Placement for Video Conferencing on Peer-to-Peer Swarm, 2015 IEEE International Symposium on Multimedia, 2015.
DOI : 10.1109/ism.2015.125

P. Troubil, H. Rudova, and P. Holub, Media Streams Planning with Transcoding, 2013 IEEE 12th International Symposium on Network Computing and Applications, 2013.
DOI : 10.1109/NCA.2013.46

Y. Wu, C. Wu, B. Li, and F. C. Lau, vSkyConf, Proceedings of the second ACM SIGCOMM workshop on Mobile cloud computing, MCC '13, 2013.
DOI : 10.1145/2491266.2491273

Y. Feng, B. Li, and B. Li, Airlift: Video conferencing as a cloud service using inter-datacenter networks, 2012 20th IEEE International Conference on Network Protocols (ICNP), 2012.
DOI : 10.1109/ICNP.2012.6459966

URL : http://iqua.ece.toronto.edu/~bli/papers/yfeng-icnp12.pdf

C. Liang and Y. Liu, Optimal Resource Allocation in Multi-Source Multi- Swarm P2P Video Conferencing Swarms, IEEE/ACM Trans. on Networking, 2011.

Y. Zhao, Y. Liu, C. Chen, and J. Zhang, Enabling P2P One- View Multiparty Video Conferencing, IEEE Transactions on Parallel and Distributed Systems, vol.25, issue.1, 2014.

H. Zhao, D. Smilkov, P. Dettori, J. Nogima, F. A. Schaffa et al., A Feasibility Study of Collaborative Stream Routing in Peer-to-Peer Multiparty Video Conferencing, 2011 IEEE International Symposium on Multimedia, 2011.
DOI : 10.1109/ISM.2011.45

D. Smilkov, H. Zhao, P. Dettori, J. Nogima, F. A. Schaffa et al., Non-intrusive Adaptive Multi-media Routing in Peerto-Peer Multi-party Video Conferencing, IEEE International Symposium on Multimedia, 2010.
DOI : 10.1109/ism.2010.24

L. Xin, G. Jianfeng, and Z. Hongke, Distortion Optimized Mobile Multiparty Video Conferencing, 2009 WRI International Conference on Communications and Mobile Computing, 2009.
DOI : 10.1109/CMC.2009.295

D. Chattopadhyay, A. Sinha, and T. Chattopadhyay, A Low Cost Multiparty H.264 Based Video Conference Solution for Corporate Environment, 2010 International Conference on Computational Intelligence and Communication Networks, 2010.
DOI : 10.1109/CICN.2010.24

X. Zhang, C. Li, and X. Li, Multi-party Videoconferencing Based on Hybrid Multicast with Peer-Forwarding, 2010 IEEE 16th International Conference on Parallel and Distributed Systems, 2010.
DOI : 10.1109/ICPADS.2010.91

M. Ponec, S. Sengupta, M. Chen, J. Li, and P. A. Chou, Optimizing Multi-Rate Peer-to-Peer Video Conferencing Applications, IEEE Transactions on Multimedia, vol.13, issue.5, p.5, 2011.
DOI : 10.1109/TMM.2011.2161759

URL : http://home.ie.cuhk.edu.hk/~mhchen/papers/p2p.conf.multirate.TMM.pdf

S. Nari, H. R. Rabiee, A. Abedi, and M. Ghanbari, An Efficient Algorithm for Overlay Multicast Routing in Videoconferencing Applications, 2009 Proceedings of 18th International Conference on Computer Communications and Networks, 2009.
DOI : 10.1109/ICCCN.2009.5235342

X. Chen, M. Chen, B. Li, Y. Zhao, Y. Wu et al., Celerity, Proceedings of the 19th ACM international conference on Multimedia, MM '11, 2011.
DOI : 10.1145/2072298.2072362

Z. Wang, J. Zhao, W. Xi, and Z. Jiang, A Scalable P2P Video Conferencing System Based on VCStream Model, 11th International Conference on Computer and Information Science, 2012.

K. Singh and V. Krishnaswamy, Building Communicating Web Applications Leveraging Endpoints and Cloud Resource Service, 2013 IEEE Sixth International Conference on Cloud Computing, 2013.
DOI : 10.1109/CLOUD.2013.39

F. Zhiyuan, L. Wei, F. Zhang, Z. Fang, D. Huang et al., A Cloud-Based Pan-Terminal Video Conferencing System, 2013 IEEE 10th International Conference on e-Business Engineering, 2013.
DOI : 10.1109/ICEBE.2013.69

T. Le and H. Nguyen, Application-aware cost function and its performance evaluation over scalable video conferencing services on heterogeneous networks, 2012 IEEE Wireless Communications and Networking Conference (WCNC), 2012.
DOI : 10.1109/WCNC.2012.6214155

URL : https://hal.archives-ouvertes.fr/hal-00703013

D. and B. Khedher, A Peer-to-Peer self-organizing scheme for multiparty session, 2012 IEEE International Conference on Communications (ICC), 2012.
DOI : 10.1109/ICC.2012.6364949

H. Liu, Z. An, and Y. Lv, Audio-video conference systems design and implementation base on P2P and multicast, 2011 International Conference on Electronics, Communications and Control (ICECC), 2011.
DOI : 10.1109/ICECC.2011.6066379

T. Le and H. Nguyen, Perception-Based Application Layer Multicast Algorithm for Scalable Video Conferencing, IEEE Global Telecommunications Conference, 2011.
URL : https://hal.archives-ouvertes.fr/hal-00625862

T. Le and H. Nguyen, Centralized and distributed architectures of scalable video conferencing services, 2010 Second International Conference on Ubiquitous and Future Networks (ICUFN), 2010.
DOI : 10.1109/ICUFN.2010.5547169

URL : https://hal.archives-ouvertes.fr/hal-00625807

O. Istemi-ekin-akkus, M. R. Ozkasap, and . Civanlar, Peer-to-peer multipoint video conferencing with layered video, Journal of Network and Computer Applications, issue.34, 2011.

T. Le and H. Nguyen, Perception-based Application Layer Multicast Algorithm for scalable video conferencing, IEEE Global Telecommunications Conference, 2011.
URL : https://hal.archives-ouvertes.fr/hal-00625862

T. A. Le and H. Nguyen, Human perception-based distributed architecture for scalable video conferencing services: theoretical models and performance, annals of telecommunications - annales des t??l??communications, vol.4, issue.4, pp.1-2, 2014.
DOI : 10.1007/s10257-005-0024-3

URL : https://hal.archives-ouvertes.fr/hal-01261282

I. Rimac, V. Hilt, M. Tomsu, V. Gurbani, and E. Marocco, A Survey on Research on the Application-Layer Traffic Optimization (ALTO) Problem, 2010.
DOI : 10.17487/rfc6029

URL : https://www.rfc-editor.org/rfc/pdfrfc/rfc6029.txt.pdf

D. Finstad, H. Stensland, H. Espeland, and P. Halvorsen, Improved Multi-Rate Video Encoding, 2011 IEEE International Symposium on Multimedia, 2011.
DOI : 10.1109/ISM.2011.53

URL : http://heim.ifi.uio.no/%7Epaalh/publications/files/ism2011.pdf