Prof. Pallapa Venkataram, Electrical Communication Engineering, Indian Institute of Science, Bangalore – 560012, India. Multimedia Communications. Objectives. To know the networking evolution. To understand the network types.
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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.
Network deployment issues
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 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.
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.
Communication system - A system or facility capable of providing information transfer between persons and equipment.
CD-ROM: “Compact disk read-only memory.”
Client-Server 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).
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
Interactive Multimedia Design
Latency and Bandwidth
LAN Access Method
Frame and Packet Structures
Identify packets that require special handling.
Be capable of accommodating those special requirements.
Bandwidth Requirement, Reservation and Conservation
High bandwidth and low latency
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.
Digital Video (DV)
Analog to Digital devices
Digital Video Software
Multimedia over TCP
Multimedia over UDP
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-level tasks like assembly and synchronization. These have to be done at application level.
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
RR: Receiver report, for reception statistics from session participants, that are not active
SDES: Source description items, including CNAME
BYE: Indicates end of participation
APP: Application specific functions
SAP & SDP
Peer to peer communication, the concept of session.
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.
SDR, VIC, VAT and RAT, WB, NTE.
Network control protocol
Allows data receiver to request a special end-to-end quality of service for its data flows.
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.
High-Density File Transfers
Graphics File Transfers
Audio File Transfers
Video File Transfers
Computer-Based Audio Conferencing