270 likes | 632 Views
How Streaming Media Works. Bilguun Ginjbaatar IT 665 Nov 14, 2006. 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.
E N D
How Streaming Media Works Bilguun Ginjbaatar IT 665 Nov 14, 2006
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
Playing compressed video or sound in real time as it is downloaded over the internet
Capture Audio Source -Microphone -CD Optimizing the Audio Source -Use sound editor 3. Encoding the streaming audio clip -choose streaming format -choose one or several streamingbandwidth 4. Deliver the streaming audio clip -broadcast is available through website -If combined with another streaming clip, create SMIL file. Streaming Audio
Streaming Audio Bit Rates Internet Radio=56 Kbps, Talk show=32 Kbps, Stereo & CD Quality=256 Kbps
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?
How does EUP broadcast the Commencement Ceremony? Windows Media Encoder http://147.64.32.6 Firewire 64Kbps 256 Kbps Windows 2003 Server http://147.64.32.8: Port 1185 Ross Hall
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)
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
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
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: 16384 – 32767
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.
RTP Packet Real-time Transport Protocol
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
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.
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)
Reference • www.google.com • www.microsoft.com • www.realnetworks.com • www.RealNetworks.com • www.ShoutCast.com • www.StreamCast.com • www.wikipedia.org