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Internet Video

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The Video/Multimedia streaming in Internet and the Internet stability problem.

The Video/Multimedia streaming in Internet and the Internet stability problem.

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  • 1. Internet & Video Salvatore Loreto Salvatore.loreto@ieee.org www.sloreto.com May 21st, 2009 1
  • 2. Outline Ì Internet Video vs IPTV Ì MultiMedia Streaming Ì The Internet Stability Ì UDP a challenge for the future Ì Suggestions 2
  • 3. Outline Ì Internet Video vs IPTV Ì MultiMedia Streaming Ì The Internet Stability Ì UDP a challenge for the future Ì Suggestions 3
  • 4. Internet Video vs IPTV Internet Video: IPTV: Internet Video runs on Is a provider offered, top of the Best managed service with Effort network certain quality of service requirements. Ì Challenge: Ì The provider does not Deal with multimedia in a best- simultaneously broadcast effort network: everything due to limited technical challenges bandwidth on the access network Ì Challenge: How the Internet might evolve to better support multimedia? 4
  • 5. Outline Ì Internet Video vs IPTV Ì MultiMedia Streaming Ì The Internet Stability Ì UDP a challenge for the future Ì Suggestions 5
  • 6. MultiMedia Classes of MultiMedia: Fundamental characteristics: 1) Streaming stored Ì Typically delay sensitive r end-to-end delay 2) Streaming live r delay jitter 3) Real-time interactive Ì But loss tolerant: infrequent losses cause minor glitches 6
  • 7. Streaming Stored Multimedia Streaming: Ì media stored at source Ì transmitted to client Ì streaming: client playout begins before all data has arrived Ì timing constraint for still-to-be transmitted data: in time for play out 7
  • 8. Streaming Stored Multimedia: Interactivity Ì VCR-like functionality: client can pause, rewind, FF, push slider bar r 10 sec initial delay OK r 1-2 sec until command effect OK 8
  • 9. Streaming Live Multimedia Examples: Ì Internet radio talk show Ì Live sporting event Streaming Ì play can lag tens of seconds Ì still have timing constraint (but shorter delay required) Interactivity Ì fast forward impossible Ì rewind, pause possible! 9
  • 10. Interactive, Real-Time Multimedia Ì applications: IP telephony, video conference, distributed interactive worlds Ì end-end delay requirements: r audio: < 150 msec good, < 400 msec OK • includes application-level (packetization) and network delays • higher delays noticeable, impair interactivity Ì session initialization r callee be able to advertise its IP address, port number, encoding algorithms. 10
  • 11. Multimedia telephony services -P2PSIP realization SN A DSN UE A UE B SN E AAA server Ì P2PSIP in an IETF protocol that uses the Session Initiation Protocol (SIP) for establishing and managing sessions in a Peer to Peer network. In this scenario the DHT are only used to discover the peer to communicate with. The streaming for the call happens end to end.
  • 12. Streaming services-PPSP realization Distribute Service Network Ì Peer to Peer Streaming Protocol (PPSP) the aim of this protocol is locating and transmitting real- time data efficiently from multiple sources with different pieces in peer to peer environment.
  • 13. Content distribution It is not clear yet if a pure P2P distribution is good for streaming and especially for live streaming!
  • 14. Outline Ì Internet Video vs IPTV Ì MultiMedia Streaming Ì The Internet Stability Ì UDP a challenge for the future Ì Suggestions 14
  • 15. The Internet Stack APPLICATION TCP/UDP IP Link 15
  • 16. The Internet Stability The stability of the Internet is what allow everybody to send and receive data on the Internet without occupy all the available bandwidth. 16
  • 17. The Internet Stability Ì The stability of the Internet is due to the TCP congestion control algorithm Ì ...Indeed almost all the Internet traffic nowadays is over TCP Ì ...This is the reason for which many Web sites (e.g. Youtube) that host small length and low resolution videos use only pseudo-streaming technologies that are based on the simple TCP download Ì ...In this way the generated traffic is not harmful for the stability of the Internet 17
  • 18. Streaming from Web Server Ì multimedia files stored in Web servers Ì Browser requests file with HTTP request message Ì Web server sends file in Browser launches media player, and HTTP response message passes file to media player Ì Content-type header line indicates an audio/video encoding Open Issues Ì How to improve Browser launches media player and passes it the HTTP streaming meta file. Player sets up a TCP connection with Ì HTML 5 server and sends HTTP request 18
  • 19. The Internet Stability Ì ...moreover, it is not clear if the perceived quality is satisfactory for the user Ì ...indeed TCP doe not provide content delivery within delay constrains Ì ...the TCP congestion control is not optimal for VoIP/Multimedia application As consequence, audio and video applications are in practices transported by hidden proprietary protocols using the UDP protocol 19
  • 20. Outline Ì Internet Video vs IPTV Ì MultiMedia Streaming Ì The Internet Stability Ì UDP a challenge for the future Ì Suggestions 20
  • 21. UDP a challenge for the future Ì UDP protocol does not employ a congestion control neither a retransmission mechanism Ì ... that means that it can an application using UDP can consume all the available bandwidth causing congestion However the usage of UDP is increasing lately for different reasons. The mains are: Ì UDP works very well with the NAT Ì UDP is optimall for multimedia streams 21
  • 22. UDP a challenge for the future Ì ...multimedia streaming service can tolerate some low packet loss percentage, but require more tight quality of service (QoS) requirements in terms of: - end-to-end delay - jitter 22
  • 23. UDP a challenge for the future Ì RTP/RTCP/RTSP are protocols that have been designed to run on top of UDP, to transport multimedia streaming RTP: RTCP: provides provides Ì Payload type Ì Minimal control to the identification application Ì Sequence numbering Ì Quality monitoring Ì Time-stamping service for RTP transport 23
  • 24. RTSP/RTCP/RTP HTTP GET Web Web browser presentation desc. server RTSP media player RTCP media server RTP client server RTSP: Real-Time Signaling Protocol RTCP: Real-Time Control Protocol RTP: Real-Time Transport Protocolc 24
  • 25. RTSP: Initialization and Control HTTP GET Web Web browser presentation desc. server SETUP PLAY media media stream (RTP) media player server RTCP PAUSE TEARDOWN client server 25
  • 26. UDP a challenge for the future Ì ...UDP lacks congestion control algorithms Ì … however High-bandwidth UDP applications must implement congestion control themselves - a difficult task – or risk rendering congested network unusable! 26
  • 27. UDP a challenge for the future Ì ...RTP/RTCP/RTSP do not provide any congestion control neither Ì ..so all the applications that use RTP/RTSP to transport media (e.g. Skype) SHOULD implement a proprietary form of congestion control algorithm to reduce the sending rate when a big packet loss rate is measured The problem is that those proprietary algorithms are much more aggressive that the TCP one! 27
  • 28. UDP a challenge for the future Is not clear YET the impact of Multimedia traffic on the Stability of the Internet when a VERY large amount of this traffic will populate the network It is a challenge to Telecom operators and ISP both from the point of view of Ì business model and Ì network stability 28
  • 29. Outline Ì Internet Video vs IPTV Ì MultiMedia Streaming Ì The Internet Stability Ì UDP a challenge for the future Ì Suggestions 29
  • 30. Suggestions From a protocol point of view, -there is a need to standardize and implement the right algorithm: Ì e.g. RFC 5348 “TCP Friendly Rate Control (TFRC) Protocol Specification” -there is a need to recover from relatively infrequent and short bursts of loss using a combination of video and packet recovery mechanisms and protocols e.g.: Ì Forward Error Correction (FEC) Ì Retransmission approach based on RTP/RTCP 30
  • 31. Suggestions From a network point of view, there is a need to increase the bandwidth and improve its usage Ì the optical Broadband (for the wireline) Ì Multimedia Broadcast Multicast Service (MBMS) (for the wireless) 31
  • 32. Q&A @$%#^*&% %^&#$ *&^$ %^ !@! @^&% %$
  • 33. RTMP – Real Time Messaging Protocol Real Time Messaging Protocol (RTMP) is a proprietary protocol developed by Adobe System for streaming audio, video and data over the Internet, between a Flash player and a server. • It works on top of TCP • Or can be encapsulated within HTTP requests to traverse firewalls. There are also other companies working on similar protocol based on TCP or encapsulated in HTTP e.g. Apple
  • 34. Datagram Congestion Control Protocol (DCCP) ( RFC 4340) Is a new transport protocol that adds o a UDP- like foundation the minimum mechanisms necessary to support congestion control. It is a message-oriented and implements: - Reliable connection setup, teardown - ECN - Congestion control - Feature negotiation