1 How Streaming Media Works Bilguun Ginjbaatar IT 665 Nov 14, 2006

2 Outline Introduction: What’s Streaming? Source Material for Streaming Streaming Technology Streaming Servers Media Players Streaming Audio Streaming Video Bandwidth How Does Edinboro University broadcast? Protocols

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4 Playing compressed video or sound in real time as it is downloaded over the internet

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Streaming Audio 1.Capture Audio Source -Microphone -CD 2.Optimizing the Audio Source -Use sound editor Encoding the streaming audio clip 3.Encoding the streaming audio clip -choose streaming format -choose one or several streaming bandwidth Deliver the streaming audio clip 4.Deliver the streaming audio clip -broadcast is available through website -If combined with another streaming clip, create SMIL file.

13 Streaming Audio Bit Rates Internet Radio=56 Kbps, Talk show=32 Kbps, Stereo & CD Quality=256 Kbps

14 Applications

15 Streaming Bandwidth and Storage Usual Video window size: 320 x 240 Streaming Media Storage Size –Megabytes –Gigabytes –Terabytes What’s the Storage Size for 1 hour of video, encoded at 300kb/s?

16 Streaming Video (Webcast)

17 How does EUP broadcast the Commencement Ceremony? Firewire Windows 2003 Server Port 1185 Ross Hall Windows Media Encoder 64Kbps 256 Kbps

18 Protocols User Datagram Protocol (UDP) Real-Time Streaming Protocol (RTSP) Real Data Transport (RDT) Real-time Transport Protocol (RTP) Real-Time Transfer Control Protocol (RTCP) Resource ReSerVation Protocol (RSVP)

19 UDP Sends media as series of small packets Provides connectionless & best-effort message service Simple & efficient Packets are liable to be lost or corrupted Client may use Error Correction to recover data or Drop Out

20 RTSP Developed in 1998 as RFC-2326 Allows client remotely control: play, pause, next Clients: RealPlayer, VideoLAN, MPlayer, Windows MP, Quicktime Session ID is used to keep track –No permanent TCP connection needed RTSP requests based on HTTP –DESCRIBE: includes rtsp://… –SETUP: request specifies how a single media stream must be transported –PLAY: request will cause one or all media streams to be played –RECORD: used to send a stream to the server for storage –TEARDWON: used to terminate the session

21 RDT Real Data Transport proprietary transport protocol for audio/video Developed by RealNetworks in 1990’s. Tolerant to loss. Works in companion with RTSP. Uses ports: – 32767

22 RTP Real-time Transport Protocol Provides end-to-end delivery interactive audio/video over the internet. Can be used for VOIP applications: Skype, VoipCheap 1996: RFC 1889 => 2003: RFC 3550 Does not have standard TCP or UDP port to communicate UDP connections are done only via an 2n port. 2n+1 port is used for RTCP communications.

23 RTP Packet Real-time Transport Protocol

24 RTCP Sister protocol of Real-time Transport Protocol (RTP) Defined in RFC 3550 Partners with RTP in delivery of multimedia data DOES NOT transport any data itself Monitors participating packets in steaming multimedia session. –Sends control packet to get feedback on QoS –Gathers stat info on: bytes sent, bytes received, lost packets, jitter, roundtrip delay Types of RTCP: –Sender Report Packet –Receiver Report Packet –Source Description RTCP packet –Goodbye RTCP packet SRTCP (Secure) is used for encryption, authentication, and integrity

25 RSVP Transport Layer protocol designed to reserve resources across the Internet Described in RFC 3936 (Oct 2004) Can be used by HOSTS or ROUTERS Delivers specific QoS for data streams RSVP is not a routing a protocol, but works with other routing procols. Notice: RSVP is rarely deployed by tele-com networks today Traffice Engineering RSVP (RSVP-TE) is available now. RSVP requests resources for simplex flows: a traffic stream in only one direction from sender to one or more receivers.

26 Conclusion Streaming is used widely everywhere To stream a media you will need: camera, firewire, encoder, server, and a high speed internet connection Media Players: Adobe Flash Player, Windows Media Player. How Streaming Audio & Video works. Streaming Bit Rates differ: higher the bit rate the better quality. The Protocols used: –User Datagram Protocol (UDP) –Real-Time Streaming Protocol (RTSP) –Real Data Transport (RDT) –Real-time Transport Protocol (RTP) –Real-Time Transfer Control Protocol (RTCP) –Resource ReSerVation Protocol (RSVP)

27 Reference