Chapter 4-Multimedia Communications

8/9/2019 Chapter 4-Multimedia Communications

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Multimedia Communications


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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.


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Networking Infrastructure Evolution Network deployment issues


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Network Topologies Evolution LAN

Linear topology

Star-wired

Multisegment

Backbone-connected

Switched-backbonet

WLAN WAN


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Multimedia Requirements To develop schemes for multi-access networks which can

provide performance guarantees. To develop a distribute route-selection strategy for point-

to-point networks.

Real-time multimedia applications require guaranteedperformance 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.


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Communication Service for Multimedia Quality-of-service (QoS) support and group communication system:

establishment and take-down of appropriately congured channels;

negotiation of QOS levels between end-systems, 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.


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Multimedia Communication System Communication system - A system or facility capable of

providing information transfer between persons andequipment.

CD-ROM: Compact disk read-only memory.

Client-Server Model: A client makes a request and aserver fulfills that request.

Composite Video: Analog video signals can be broken

down into parts such as luminance (Black & White) andchrominance (color).


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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


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Multimedia Communication System Interactive Multimedia Design

Interlacing

Interleaved

Linear Multimedia

Non-Interactive Multimedia

Nonlinear Multimedia

Presentation Multimedia

Latency and Bandwidth


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Multimedia Application Environment


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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


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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.


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Multimedia Networks Technical Issues

Admission control

Scheduling

Resource management

Congestion control

Policing/Shaping


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Multimedia Network Reference Model


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Multimedia Hardware/Software Audio/Video Hardware

Digital Video (DV)

Analog to Digital devices

Built-in Hardware

Digital Video Software

Multimedia Software


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Comparison of Stacks


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INTERNET


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Connection to Internet


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Multimedia Internet Protocols

Multimedia over TCP

Multimedia over UDP


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RTP Real-time Transport Protocol (RTP) provides support for

the transport of real-time 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 real-time content.

RTP/RTCP itself is not responsible for the higher-leveltasks like assembly and synchronization. These have to be

done at application level.


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RTCP Real-Time 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


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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.


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Multimedia Internet Protocols RSVP

Network control protocol

Allows data receiver to request a special end-to-end quality

of service for its data flows.

RTSP A client-server 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.


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Multimedia Communications High-Density File Transfers

Graphics File Transfers

Audio File Transfers

Video File Transfers

Audio Communication Computer-Based Telephony

Computer-Based Audio Conferencing

Streaming Audio

Video Communication

Video Conferencing

Streaming Video

Documents

Chapter 4-Multimedia Communications