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  1. 1. E0262 - Multimedia Communications Prof. Pallapa Venkataram, Electrical Communication Engineering, Indian Institute of Science, Bangalore – 560012, India Multimedia Communications
  2. 2. E0262 - Multimedia Communications Objectives ● To know the networking evolution. ● To understand the network types. ● To discuss multimedia requirements in the  communication systems. ● To understand the basics of a multimedia communication  system. ● To illustrate multimedia networks. ● To know the Internet protocol suite for multimedia  communications.
  3. 3. E0262 - Multimedia Communications Networking Infrastructure Evolution ● Network deployment issues
  4. 4. E0262 - Multimedia Communications Network Topologies Evolution ● LAN – Linear topology – Star­wired – Multisegment – Backbone­connected – Switched­backbonet ● WLAN ● WAN
  5. 5. E0262 - Multimedia Communications Multimedia Requirements ● To develop schemes for multi­access networks which can  provide performance guarantees.  ● To develop a distribute route­selection strategy for point­ to­point networks. ● Real­time multimedia applications require guaranteed  performance communication services, such as throughput,  delay, delay jitter and loss rate. ● The characteristics of a source, such as peak and average  rate, are known at channel establishment time. ● Channel parameters have to be predicted in live  continuous video sources.
  6. 6. E0262 - Multimedia Communications Communication Service for Multimedia ● Quality­of­service (QoS) support and group communication system: – establishment and take­down of appropriately congured  channels; – negotiation of QOS levels between end­systems, intermediate  systems, and network control; and – control of the agreed QOS level ● bandwidth, delay, delay jitter (variance), and reliability. ● Audio/Video groups can: – have static or dynamic memberships during their lifetime, – have centrally (typically sender) or distributedly (typically receiver)  controlled membership, – consist of members with homogeneous or be heterogeneous  characteristics and requirements.
  7. 7. E0262 - Multimedia Communications Multimedia Communication System ● Communication system ­ A system or facility capable of  providing information transfer between persons and  equipment. ● CD­ROM: “Compact disk read­only memory.” ● Client­Server Model: A client makes a request and a  server fulfills that request. ● Composite Video: Analog video signals can be broken  down into parts such as luminance (Black & White) and  chrominance (color).
  8. 8. E0262 - Multimedia Communications Multimedia File types ● Here are some examples of le types: ● Text Files: .txt, .doc, .rtf ● Audio Files: .au, .aif, .wav ● Graphic files: .jpg, .gif, .tif, .bmp, .pict, .pcx ● Moving video files: .qt, .mov, .avi ● Animation: .fli, .flc
  9. 9. E0262 - Multimedia Communications Multimedia Communication System ● Interactive Multimedia Design ● Interlacing ● Interleaved ● Linear Multimedia ● Non­Interactive Multimedia ● Nonlinear Multimedia ● Presentation Multimedia ● Latency and Bandwidth
  10. 10. E0262 - Multimedia Communications Multimedia Application Environment
  11. 11. E0262 - Multimedia Communications Multimedia Communication System ● LAN Access Method ● Routing ● Frame and Packet Structures ● Packet Discrimination ● Identify packets that require special handling. ● Be capable of accommodating those special requirements. ● Bandwidth Requirement, Reservation and Conservation ● High bandwidth and low latency
  12. 12. E0262 - Multimedia Communications Multimedia Communication System Architecture ● The ability to manage dynamically the achieved QoS of each service  component ● The possibility for users to select some resources that best meet their  needs. ● The possibility to interact with another user whose equipment has differing  characteristics. ● The communications network must allow any user to select the service  components he/she wants: ● The possibility for users to join in or withdraw from a communication  session according to certain policies, such as agreement of all interacting  partners before admitting a new user. ● The possibility to set such quality of service parameters as the  synchronization tolerance between the service components, the echo  sensitivity, the burst sensitivity, and so on.
  13. 13. E0262 - Multimedia Communications Multimedia Networks ● Technical Issues – Admission control – Scheduling – Resource management – Congestion control – Policing/Shaping
  14. 14. E0262 - Multimedia Communications Multimedia Network Reference Model
  15. 15. E0262 - Multimedia Communications Multimedia Hardware/Software ● Audio/Video Hardware ● Digital Video (DV) ● Analog to Digital devices ● Built­in Hardware ● Digital Video Software ● Multimedia Software
  16. 16. E0262 - Multimedia Communications Comparison of Stacks
  17. 17. E0262 - Multimedia Communications INTERNET
  18. 18. E0262 - Multimedia Communications Connection to Internet
  19. 19. E0262 - Multimedia Communications Multimedia Internet Protocols ● Multimedia over TCP ● Multimedia over UDP
  20. 20. E0262 - Multimedia Communications RTP ● Real­time Transport Protocol (RTP) provides support for  the transport of real­time data such as video and audio  streams. ● RTP needs support from lower layers that actually have  control over resources in switches and routers ● RTP/RTCP provides functionality and control  mechanisms necessary for carrying real­time content. ● RTP/RTCP itself is not responsible for the higher­level  tasks like assembly and synchronization. These have to  be done at application level.
  21. 21. E0262 - Multimedia Communications RTCP ● Real­Time Control Protocol extends RTP ● In an RTP session, participants periodically send RTCP packets to convey  feedback on quality of data delivery and information of membership. ● Packets defined for carrying control information: – SR: Sender report, for transmission and reception statistics from  session participants that are – active senders. – RR: Receiver report, for reception statistics from session participants,  that are not active – senders. – SDES: Source description items, including CNAME – BYE: Indicates end of participation – APP: Application specific functions
  22. 22. E0262 - Multimedia Communications Multimedia Internet Protocols ● SAP & SDP – Peer to peer communication, the concept of session. ● SIP – Signaling mechanisms that are necessary to establish a  session and to negotiate the parameters to be used in it,  such as codecs, media, location, etc. ● MBONE Tools – SDR, VIC, VAT and RAT, WB, NTE.
  23. 23. E0262 - Multimedia Communications Multimedia Internet Protocols ● RSVP – Network control protocol – Allows data receiver to request a special end­to­end quality  of service for its data flows. ● RTSP – A client­server multimedia presentation protocol to enable  controlled delivery of streamed multimedia data over IP  network. – Aims to provide the same services on streamed audio and  video just as HTTP does for text and graphics. 
  24. 24. E0262 - Multimedia Communications Multimedia Communications ● High­Density File Transfers ● Graphics File Transfers ● Audio File Transfers  ● Video File Transfers ● Audio Communication ● Computer­Based Telephony ● Computer­Based Audio Conferencing ● Streaming Audio ● Video Communication ● Video Conferencing ● Streaming Video