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Multimedia Streaming CE00164-3

Multimedia Streaming CE00164-3. Module Information. Module code CE00164-3 Module Title MULTIMEDIA STREAMING Level 3 (Semester 2) Credit Value 15 Lecture/Teaching Areas E6 Module Tutor Mohamed Abdel Maguid Room C207, Tel 01785 353324 m.m.abd-el-maguid@staffs.ac.uk

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Multimedia Streaming CE00164-3

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  1. Multimedia Streaming CE00164-3

  2. Module Information • Module code CE00164-3 • Module Title MULTIMEDIA STREAMING • Level 3 (Semester 2) • Credit Value 15 • Lecture/Teaching Areas E6 • Module Tutor • Mohamed Abdel Maguid • Room C207, Tel 01785 353324 • m.m.abd-el-maguid@staffs.ac.uk • Module Moderator • Tim Dunning • Room C206, Tel – 01785 353433 • t.s.dunning@staffs.ac.uk

  3. Accessing documents • Resources • Blackboard for all documents

  4. You will study • The theory and practice of Media Streaming • How streaming media is created and delivered to the world. • Windows Media Streaming using specialised Media Servers design to stream high bandwidth media content. • Computer networks • Video encoding • SMIL to integrate presentations and media content. • Management of media rights, authentication and conditional access

  5. Assessment • The assessment is to create in pairs a synchronised media presentation and streaming it live. • A presentation of it is also required to demonstrate your understanding of the theory and practice. • There will also be 2 compulsory multiple choice tests on Blackboard conducted at separate times during the term.

  6. Attendance • All students are expected to attend every week and conduct 4 hours of homework per week. • The material delivered each week is the homework and must be studied in time for the lesson that follows it.

  7. Timetable • Lecture is on Monday 11-12 in E6. • The tutorial is Thursday 1-3 in E6. • You have been given one additional session to use the E6 lab to practice using the servers on Wednesday 12-1.

  8. Teaching Plan • Week 1: Introduction to module • Investigating and using Google Video / You Tube • Week 2: Theory of Streaming Media • Week 3: Introduction to Networking • Intro to on demand streaming • Week 4: Introduction to video coding • Intro to live streaming • Week 5: Principles of encoding for the web • More Live Streaming • First multiple choice test • Week 6: Digital Media Access Rights – Load balancing • Week 7: Introduction to SMIL • Week 8: Introduction to SMIL • Week 9: Introduction to SMIL • Second Multiple choice test • Week 10: Wireless Streaming with Aztec • Week 11: Flash Streaming • Week 12: Independent study week

  9. Basic Streaming • What is streamed media? • A) when the complete file is downloaded first before playback? • B) It is how TV is delivered to the home • C) Or when only a small number of packets of video required and the computer memory builds up a few seconds of video and instantly plays I back? • Answer • It can be A and C

  10. What are the basic requirements for Streaming media? • Correctly encoded media content • Specialised computer servers • High speed high bandwidth networks • A media player device that can receive the video stream • Transportation protocols to ensure real time delivery of information

  11. Basic forms of Streaming • Progressive Download • Commonly called download and play • Issues? • Video is stored in a temporary file on hard drive thus occupying space. • Cannot be sure on what bitrate the file is until it has fully downloaded. An issue on a low bandwidth connection. • Can saturate your network connection. • True streaming • Advantages? • Does not occupy any hard disc space • Efficient streaming • Does not saturate your network connection • User controls are available.

  12. Basic Uses and Services • Streaming radio stations • Promotional videos • Short News Articles • Longer video broken up into chapters • Education and entertainment • Offer on Demand Televisions programmes • Multiple languages and subtitles

  13. What devices can be streamed to? • Computers • Mobile Phones • PDA’s • Blackberry’s • Games Consoles • Anything with an Internet connection and a media player

  14. Week 2 Streaming

  15. What is required to view a stream? • A specific plugin on your device • Plugins include • Windows Media Player • Real Player • Quicktime player • Flash Player

  16. How do you stream? Media Server Encoder Internet

  17. How Does Streaming Work? 2 Web Server returns location of media file User clicks on stream link Media player is launched Media player requests media file from media server Media server sends stream to media player 5 4 1 3 1 Web Server 2 3 Media Server 4 5 Media player decompresses and plays stream 6

  18. How does it work? • File encoded and compressed to a smaller file • Break it into small packets • Send them one after the other • When the packets reach their destination, they are decompressed and resembled into a form that can be played • Playing a music or video file as it is downloaded from the internet. • Copy is never stored on the user’s computer.

  19. How does it work? (Cont) • To maintain the seamless play the packets are buffered in memory • Process by which the media player downloads a few seconds of the media file prior to actual playback. • Allows for uninterrupted playback as when buffer plays more packets are downloaded and queued for playback • Streams can be opened before a download is complete • Organised to be rendered ASAP • Play as data is received

  20. Open Connection • Streaming media files maintain an open connection • Media server and media client negotiate connection • Sent over the connection until the entire file has been received • Media clients play data over the open connection • Is buffered to overcome congestion

  21. Playback Rates • Streams can be encoded and downloaded at different bit rates. • Measured in kbps (kilobits per second). • 128 kbps is considered to be CD quality when using special codecs. • 1-2Mbps is considered to be DVD / Broadcast quality. • User’s bandwidth determines that maximum bit rate that can be played. • Can select the usual connection speed or give various options

  22. Encoding • The process of digitizing and compressing a piece of traditional media into a format capable of being broadcast over the internet and played by a computer • Raw data is typically uncompressed • Big files - Contains all data essential to proper play • Raw data is then encoded (compressed) to stream • Encoders use audio and video codecs to compress data • Compression is different for audio and video

  23. Codecs • Stands for Compression and Decompression • Compresses multimedia content prior to transmission and decompresses upon playback. • This uses less bandwidth and increases playback speed. • Users must have the proper media player to stream each format.

  24. Sound/Music Codecs • MPEG-1 layer 3 (MP3) • 8 to 320kbs • Qdesign (Quicktime) • Basic – 8 to 48kbs • Pro – 4 to 128kbs • MPEG4 (v1,v2,v3,v7,v10) • 2kbs to 2mbs

  25. MPEG • MPEG (Moving Picture Experts Group), develops standards for digital video and digital audio compression. • MPEG-1 was designed for coding progressive video at a transmission rate of about 1.5 million bits per second. It was designed specifically for Video-CD and CD-i media. • MPEG-1 audio layer-3 (MP3) has also evolved from early MPEG work.

  26. MPEG (Cont) • MPEG-2 was designed for coding interlaced images at transmission rates between 1 and 80 megabits per second. • MPEG-2 is used for digital TV broadcast and DVD. An MPEG-2 player can handle MPEG-1 data as well. • A proposed MPEG-3 standard, intended for High Definition TV (HDTV), was merged with the MPEG-2 standard

  27. MPEG4 and beyond…. • The standard for multimedia for the web and mobility. • MPEG-4 is able to throw away a lot more information and to save files 8 to 12 times smaller than those of MPEG-2. • Divx is based upon MPEG-4

  28. MPEG-4 • Real power of MPEG-4 is the interactivity that can built into the video file or stream. • Multimedia producers and software and game developers can isolate parts of the video for particular special effects. • Pocket PC devices and Windows CE already play back MPEG-4 and related codecs.

  29. Encoding Streaming Video • Choice of formats • Real Video (Helix) • QuickTime • Windows Media • Flash Video Streaming (New up and coming)

  30. Choice of delivery speeds • What connection are you streaming to? • Dial up modem (56Kbps) • ISDN/Dual ISDN (64/128Kbps) • Cable 128 up to 100Mb per sec • ADSL (copper twisted pair up to 16Mbs at least) • T-1 (1.5Mb’s) T-3 45Mbps’s • E-1 (more commonly called 2Mbps pipe)

  31. Considerations for streaming • Movie size – size affects bandwidth • Frame rates – broadcast TV is 25fps most webcasts are lower • Is it audio, video or both • Encoding the media – which format • Making a website which is suitable to play a streaming file. • Serving the media

  32. What computer hardware do you need? • A standard web server with the correct software installed OR • A specialised media server

  33. Both have streaming capabilities but why is one better than the other? • Live Streaming requires a dedicated media server • A web server is fine for low usage streaming files but if volume of people wishing to stream from your site is above 10 at a time you need a media server. • Media Servers give you much more control for your streams and offers many more services for your clients. • Media Servers enable 2 way communication the client can say rewind your media file (only for unicast).

  34. Web Server V Media Server

  35. Media Servers • Servers needed to serve streams. • In order to stream, a web site must install media servers into it’s network. • Capacity is typically measured by the maximum number of concurrent streams that the server can serve.

  36. Multiple Stream • From a normal web server • Content has been encoded for one bit rate only • Not really streaming, just being downloaded • TCP will resend lost packets and could cause playback pauses • Dedicated media server • Content can be encoded at multiple bit rates and the server will choose the right one • Server uses proprietary protocol to control content – can choose best transport • Server is tuned to provide optimum performance under heavy use – big beefy machine, multiple CPU’s, high memory and disk drive space.

  37. Media Servers • Helix Server • Real Networks • Microsoft Media Server • Quicktime Streaming Server / Darwin Streaming server • Hyperlinks use a linking file • Signals the browser to launch the streaming application • URL is passed indicating the server protocol, media server, and media file • RAM / RA – Realnetworks, ASX / WMX for Microsoft

  38. Transmission Models • Unicast • Streaming between sender and a single recipient • Multicast • Streaming between sender and multiple specific recipients • Broadcast • Streaming between a sender and any receiver • Live and prescheduled content • Some radio and television stations over WWW • Use playlists to automate playback

  39. Basic Networking Requirements • A communication protocol (language) • E.g TCP/IP and UDP • A networking standard • Ethernet, the standard for Local Area networks (LAN’s) • IP addressing • Each computer is given a unique name to identify it on an Ethernet network. • The format of an IP address is a 32-bit numeric address written as four numbers separated by periods e.g 192.168.1.1 for PC no.1, 192.168.1.2 for PC no.2 • Gateway • Give you access to the Internet (WAN – wide area network) • Ping • TTL • Switches and Routers • A means of linking computers together • It filters and forwards network packets that are sent from PC 1 to another PC

  40. Unicast streaming • One to one client server relationship • Like you playing a VCR • Communication channel remains as packets travel to client. • Allows the user to use controls like FF, RW and play.

  41. Unicast Setup

  42. Multicast • Uses watch content (Little bit like watching TV). • Media server generates one stream that allows players to connect to it. • Client connects to stream and not server • Replacement packets cannot be resent • Uses special Multicast UDP

  43. Multicast • Networks must be equipped with switches and routers supporting multicast protocols. • Efficient and cost effective. • 1 stream easier to distribute than 1000 • Uses Class D IP addressing • In range 224.0.0.0. – 239.0.0.0

  44. Multicast setup

  45. Transmission protocols • UDP V TCP • Protocols • UDP, Multicast UDP and TCP • Rollover Protocols • UDP, TCP and HTTP (MMS automatically does this when you have setup the server correctly and so does Real to)

  46. Server Delivery Protocols • TCP/IP = Transmission control protocol/internet protocol. • Dedicated media servers use proprietary delivery protocols • Server attempts to provide content over UDP (User Datagram Protocol) • If unreliable or firewall then TCP is used • Allows server to control content • Content is streamed directly to the viewer and not saved or cached

  47. Requirements for Streaming • Powerful Networks – the delivery mechanisms • Reliable Networks • Compressed media files • Transportation protocols • Real Time delivery of information • Digital Rights?

  48. Common Protocols to Learn Basics of • TCP/IP – Transmission control/Internet protocol • UDP – User Datagram protocol • RTP – Real Time Protocol • HTTP- Hyper Text Transfer Protocol • RTSP – Real Time Streaming Protocol • MMS – Microsoft Media Server protocol

  49. TCP v UDP

  50. Protocols - TCP/IP • A layer 4 protocol (transport layer) • Developed by US department of defence • Error resilient protocol for use on high error rate networks. • If packets arrive in wrong order, some are lost or corrupted it will send a message back for them to be sent again. • Problems – high latency, overhead of this guarantee is the transmission rate e.g Not very quick. • Used for lossless data packets such as images, text,etc. • Packet ordering guarantee.

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