T Multimedia Programming Maciej Korczyński, Krzysztof Zurek

Table of contents Introduction to Multimedia Streaming What is Darwin Streaming Server? The technical side Networking protocols Conclusion

Multimedia Streaming Two types of streaming: Progresive Real-time Real-time streaming works with: a streaming media server a client media player a Real-Time Streaming Protocol (RTSP) No file is ever downloaded Media is played by the client software as it is delivered

Darwin Streaming Server (1) Open source version of Apple's QuickTime Streaming Server Uses the industry standard RTP and RTSP protocols Based on the same code base as QTSS Runs on a variety of platforms

Darwin Streaming Server (2) Allows you to manipulate the code to fit your needs Code written in C/C++ Support for the latest digital media standards, like MPEG-1/2/4 or 3GPP Can stream over port 80 to avoid firewalls

What can you deliver using DSS? Broadcasts of live events in real time Video on demand Playlist broadcasts of prerecorded content

Live vs. On-Demand Delivery  Continous (Live) transmission Assistance of broadcasting needed Encoding of a live source Delivering the resulting stream to the server Each customer sees the same point in the stream at the same time  On-Demand transmission Each customer initiates the stream from the beginning No customer ever comes in “late” to the stream No broadcasting software is required

Example: Setup for Live Video (1) classroom presentation live and on demand can be seen on-line later enable students to play an archived version on their computers

Example: Setup for Live Video (2) The streaming setup in this example has features: A digital video (DV) camera and microphone are set up in a classroom or lecture hall to convert the live presentation to digital form. The DV camera is connected through a FireWire port to a laptop running QuickTime Broadcaster (it encodes the digitized live presentation and transmits the signal via an Ethernet connection to the streaming server) The streaming server with e.g DSS reflects the encoded live presentation as a unicast stream to each client computer on the campus network and on the Internet The broadcaster laptop running iMovie is used to produce high- quality on-demand versions of a live presentation after the presentation is concluded

Multicast versus Unicast (1) Multicast : a single stream is shared among the clients reduces network congestion require access to the multicast backbone

Multicast versus Unicast (2) Unicast each client initiates its own stream possible result: heavy network traffic reliable for delivery no special transport support is required

Networking protocols in DSS(1) The main networking protocols used for multimedia streaming in DSS are: Real-Time Streaming Protocol (RTSP) Real-Time Control Protocol (RTCP) Real-Time Protocol (RTP)

Networking protocols in DSS(2) Real-Time Streaming Protocol (RTSP) [7] : application-level signaling protocol control the delivery of data real-time properties establishing and managing a client/server streaming connection session initiation and media negotiation RTSP connection is finished in case the client wishes to pause, stop, rewind, or replay the media stream

Networking protocols in DSS(3) RTP and RTCP are the protocols used to transmit and control the actual media data Real-Time Protocol (RTP) [8] -> real-time multimedia transport over IP networks Real-Time Control Protocol (RTCP) [8] -> an adaptive feedback control protocol for RTP

Networking protocols in DSS(4) A media streaming session has three distinct phases: Initialization Media Transmission Session Termination

Conclusion Disscused aspects of Apple Darwin Streaming Server are: DSS represents Real-time streaming Supports multiple platforms Supports Live and On-Demand delivery Multicast and Unicast delivery is possible Networking protocols are necessary to control interaction between streaming server and matching streaming client

References: _admin_guide.pdf [1] ex.html [2] 05.pdf [3] [4] [5] [6] [7] [8]

Questions? Thanks for your attention!