Multimedia Over Internet

Growth of Internet● No production cost

● Low cost infrastructure

● No fees for joining or licenses

to buy

● Choice of products and

services

● No sales experience needed

● No employees required

● No expensive accounts

needed

● No inventory to carry

● No order processing

● No product shipping

● No customer service

concerns

● Make money while you

sleep

● The world at your doorstep

● Minimal risk

● High income potential

Multimedia Over IP Multicast Network

Multimedia Over IP Multicast Network

Delivering Real-time Multimedia over Internet

● framework for transporting real-time Internet video

includes two components: congestion control and

error control

● Congestion control consists of rate control, rate-

adaptive encoding, and rate shaping

● Error control consists of forward error correction

(FEC), retransmission, error resilience, and error

concealment

● QoS issues are bandwidth, delays and loss of data

Heterogeneity Network Environment● Network heterogeneity and Receiver heterogeneity

● Network heterogeneity refers to the subnetworks

in the Internet having unevenly distributed resources

(e.g., processing, bandwidth, storage, and

congestion control policies).

● Receiver heterogeneity means that receivers have

different or even varying latency requirements,

visual quality requirements, and/or processing

capability.

Heterogeneity Network Environment● Network-centric approach:

– Routers/switches in the network are required to provide

QoS support to guarantee bandwidth, bounded delay,

delay jitter, and packet loss for video applications (e.g.,

integrated services, or differentiated services).

● End-system based approach:

– Control techniques to maximize the video quality

without any QoS support from the transport network.

– The integrated solutions is based on both transport (use

of control/processing techniques without regard of the

specific video) and compression perspectives

(employing signal processing techniques with

consideration of the video semantics).

Heterogeneity Network Environment● Congestion Control:

● Bursty loss and excessive delay are caused by

network congestion

● Reduce packet loss and delay

● Rate control matches the rate of the video stream to

the available network bandwidth.

● Rate-adaptive video encoding or rate shaping is

required.

● Rate control is from the transport perspective, while

rate-adaptive video encoding is from the

compression perspective; rate shaping is in both

transport and compression domain.

Heterogeneity Network Environment

● Error Control

● Four types: Forward error correction (FEC),

retransmission, error resilience, and error

concealment.

● FEC adds redundant information to a compressed

video bit stream so that the original video can be

reconstructed the in presence of packet loss. Three

kinds of FEC:

– channel coding;

– source coding-based FEC;

– joint source/channel coding.

Internet Multimedia Applications● Classes of multimedia applications

● Streaming Stored Multimedia Data Applications

– Clients request on-demand data (for example,

compressed audio or video files) which is stored on

servers.

● One to many streaming of real-time data applications

– Similar to ordinary broadcast of radio and television,

except the transmission takes place over the Internet.

● Real-time interactive multimedia applications

– Allows people to use audio/video to communicate with

each other in real-time

Multimedia Data Streaming● Significant improvement over the download-and-play

approach to multimedia file distribution

● Allows the data to be delivered to the client as a

continuous flow with minimal delay before playback

can begin

● Streaming is a server/client technology that allows live

or pre-recorded data to be broadcast in real time

● Multimedia applications such as news, education,

training, entertainment, advertising, and a host of

other uses

● Streaming enables the Internet or company Intranet

as a new broadcast medium for audio and video.

Multimedia Data Streaming● Example:

● If there are 100 requests for a video stream

compressed at 28.8 Kbps,

– the server would require at least a 3 Mbps connection.

– The Encoding Station and the Video Streaming Server

can be one single system.

– However, unless hardware encoding is used, this would

typically be for a situations requiring limited

performance (e.g. a single input stream and a small

number of viewer requests).

– Even so, it would still require a fairly high-performance

system.

– It is much more common to have two separate

systems.

Multimedia Data Streaming

Unicast vs. IP Multicast● Streaming delivery techniques: Unicast and Multicast.

● Unicast: Computers establish two-way,

– point-to-point connections.

● Client computer can communicate with the computer supplying

the multimedia stream.

● Each client that connects to the server receives a separate

stream, which rapidly uses up network bandwidth.

● IP Multicast: One computer sends a single copy of the data over

the network and many computers receive that data.

– Only a single copy of the data is sent across the network, which

preserves network bandwidth.

– It is connectionless; clients have no control over the streams they

receive

Web Multimedia Information Systems● Web Process

– Organizing entity that determines a set of activities

and specifies their relations

● Activity

– Process step, which participates in the fulfillment of

an overall objective. An agent who satisfies the

required skills and rights (paradigm of role) fulfilled it.

● Activities Synchronization

– Temporal preconditions to define a temporal order

between activities, Alternatives to let the user decide

on the media to use for a specific purpose, Parallelism

between activities what is especially useful in the case

of collaborative work.

Web Information System Architecture

Interactive Web Pages

Interactive Multimedia Applications

Multimedia Services & Applications

Multimedia Services & Applications

Video Streaming

Interactive Multimedia Applications

● Flexible scheduling based on a finite set of channels

available to all viewers

● A set of channels are multicast to all viewers tuned to the

respective channel.

● Viewers may watch a program playing on any channel or

make a request for something of their own choosing.

Viewers' requests are scheduled on one of the jukebox's

channels using scheduling criteria like minimum waiting

time, etc.

● A schedule of currently playing and scheduled programs,

updated in real-time, is available to all viewers. Viewers

can watch any program, including those scheduled by

others, by tuning to the appropriate channel.

Jukebox Policies● Content-based scheduling

– Limitations may be imposed based on the content

● Service provider scheduling

– A service provider may have a desire or obligation to

schedule certain programs at certain times

● Limited viewer input

● A service provider may want to blunt the ability of

individual viewers to control what programs are

playing

Jukebox - Architecture

Jukebox - Architecture● Scheduling control: The scheduler receivers viewer

requests, performs scheduling, controls the video

server, and provides a schedule of programs to all

viewers.

● Video server: The video server transmits audio/video

streams into the network

● Network: The network must provide an effcient

multicast facility and have sufficient bandwidth to

meeting viewer quality expectations

● Receivers: Receivers must be able to receive,

decode, and display an audio/video stream.

Collaborative Work

Collaboration Work

● Client: A client can send some session requests to a

session server to create or join the session so that it

can take part in some meeting.

● Media Server: A media server is a RTP Channel for

audio and video communication between clients.

● Session Server: The session server is the core of the

XGSP, which can accept request of various clients

and organize the video conference.

Multimedia Messaging System

MMS Network Architecture

MMS Operation● Sending Messages: A user sends a message by having its MMS-

UA submit the message to its home MMS-RS.

● Receiving Messages: Upon reception of a message, the

recipient MMS-RS verifies the recipient profile and generates a

notification to the recipient MMS-UA.

● Message Adaptation: Within a request for delivery of a

message, the recipient MMS-UA can indicate its capabilities,

e.g., a list of supported media types and media formats, for the

recipient MMS-RS.t

● Delivery Reports: If a delivery report has been requested by

the originator MMS-UA and if the recipient MMS-UA did not

request a delivery report not to be generated, the recipient

MMS-RS generates a delivery report and delivers the delivery

report to the originator MMS-RS.