03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing Streaming 1

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Agenda F Types of Streaming F Unicast and Multicast mechanisms F Stream Control Transmission Protocol 2

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Types of Streaming Streaming stored audio/video refers to on- demand requests for compressed audio/video files. Streaming live audio/video refers to the broadcasting of radio and TV programs through the Internet. Interactive audio/video refers to the use of the Internet for interactive audio/video applications. 3

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 User Datagram Protocol (UDP) F Simple protocol and limited overhead as compared to IP packet. F No additional services added into the IP packet, apart from start and stop the connection. F Connectionless and unreliable transport protocol. F Independent datagram - not numbered F Suitable for simple request-response communication 4

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Transmission Control Protocol (TCP) F Connection-oriented protocol and reliable transport protocol. F Create a virtual connection between two application programs to send data. F Virtual connection – connected as in the transport layer 5

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Streaming Multimedia: UDP or TCP? UDP F server sends at rate appropriate for client (oblivious to network congestion !) –often send rate = encoding rate = constant rate –then, fill rate = constant rate - packet loss F short playout delay (2-5 seconds) to remove network jitter F error recover: time permitting TCP F send at maximum possible rate under TCP F fill rate fluctuates due to TCP congestion control F larger playout delay: smooth TCP delivery rate F HTTP/TCP passes more easily through firewalls

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Unicasting F In unicasting, the router forwards the received packet through only one of its interfaces. 7

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Multicasting F In multicasting, the router may forward the received packet through several of its interfaces 8

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Multicasting versus Multiple casting 9

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Streaming Stored Multimedia 1. video recorded 2. video sent 3. video received, played out at client Cumulative data streaming: at this time, client playing out early part of video, while server still sending later part of video network delay time

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Web Server Streaming 11 F audio or video stored in file F files transferred as HTTP object –received in entirety at client –then passed to player

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Web Server with Metafile Streaming 12 r browser GETs metafile r browser launches player, passing metafile r player contacts server r server streams audio/video to player

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Media Server Streaming 13 F allows for non- HTTP protocol between server, media player F UDP or TCP for steps (4,5)

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Media Server and RTSP Streaming RTSP - Real Time Streaming Protocol 14

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Streaming Live Multimedia Examples: F Internet radio talk show F live sporting event Streaming (as with streaming stored multimedia) F playback buffer F playback can lag tens of seconds after transmission F still have timing constraint Interactivity F fast forward impossible F rewind, pause possible!

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Real-Time Interactive Multimedia F end-end delay requirements: –audio: < 150 msec good, < 400 msec OK includes application-level (packetization) and network delays higher delays noticeable, impair interactivity F session initialization –how does callee advertise its IP address, port number, encoding algorithms? r applications: IP telephony, video conference, distributed interactive worlds

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing Real-Time Protocol (RTP) F RTP specifies packet structure for packets carrying audio, video data F RTP packet provides –payload type identification –packet sequence numbering –time stamping F RTP runs in end systems F RTP treated like application program and encapsulated in UDP segments F interoperability: if two Internet phone applications run RTP, then they may be able to work together

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing Real-Time Control Protocol (RTCP) F works in conjunction with RTP. F each participant in RTP session periodically transmits RTCP control packets to all other participants. F each RTCP packet contains sender and/or receiver reports –report statistics useful to application: # packets sent, # packets lost, interarrival jitter, etc. F feedback can be used to control performance –sender may modify its transmissions based on feedback

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing Synchronization of Streams F RTCP can synchronize different media streams within a RTP session F consider videoconferencing for which each sender generates one RTP stream for video, one for audio. F timestamps in RTP packets tied to the video, audio sampling clocks F each RTCP sender-report packet contains (for most recently generated packet in associated RTP stream): –timestamp of RTP packet –wall-clock time for when packet was created. F receivers uses association to synchronize playout of audio, video

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 20

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Stream Control Transmission Protocols F SCTP is a message-oriented, reliable protocol that combines the good features of UDP and TCP. 21

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Multiple-stream Concept 22

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Multihoming Concept 23

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Summary F SCTP is a message oriented, reliable protocol that combines the good features of UDP and TCP F SCTP provides additional services that are not provided by UDP or TCP. F More reading from Wikipedia – Protocolhttp://en.wikipedia.org/wiki/Stream_Control_Transmission_ Protocol – – – 24

03/11/2015 Michael Chai; Behrouz Forouzan Staffordshire University School of Computing IADCN - Week 10 Reading about Streaming Methods F Streaming from a Web Server ( owto/articles/webserver.aspx) F Streaming Methods: Web Server vs. Streaming Media Server ( ompare/webservvstreamserv.aspx) ompare/webservvstreamserv.aspx 25