introduction to multimedia systems and applications

1. Introduction to Multimedia
BY : Selma Abdelbagi Ibrahim

2. What is Multimedia
• Multimedia means that computer information can be
represented through audio, video, and animation in
addition to traditional media (i.e., text, graphics drawings,
images).
• A good general definition is:
• Multimedia is the field concerned with the computer-
controlled integration of text, graphics, drawings, images
,Video, animation, audio, and any other media where
every type of information can be represented, stored,
transmitted and processed digitally.

3. Multimedia Systems
• A Multimedia System is a system capable of
processing multimedia data and applications.
• A Multimedia system has four basic characteristics:
 Multimedia systems must be computer controlled.
 The information they handle must be represented
digitally.
 The interface to the final presentation of media is
usually interactive.
 Multimedia systems are integrated.

4. Desirable Features for a Multimedia
System
 Very High Processing Power:
• To deal with large data processing and real time
delivery of media.
• Special hardware commonplace.
 Capable File System
• To deliver real-time media -- e.g. Video/Audio
Streaming.
• Special Hardware/Software needed

5. Desirable Features for a Multimedia
System
 Data Representations/File Formats
• should be easy to handle yet allow for compression
/decompression in real-time.
 Efficient and High I/O
 Special Operating System
 Large Storage and Memory
 Network Support
 User friendly Software Tools

6. Components of a Multimedia System
 Capture devices
• -- Video Camera, Video Recorder, Keyboards, mice.
 Storage Devices
• Hard disks, CD-ROMs, DVD, etc
• Communication Networks
• Ethernet, Token Ring, FDDI, ATM, Intranets, Internets.
• Computer Systems
• Multimedia Desktop machines, Workstations
 Display Devices
• speakers, monitors, Colour printers etc.

7. Multimedia information
representation
• Applications involving text and images comprise
blocks of digital data
 Text: block of characters with each represented by a
fixed number of bits (codeword)
• Digitized Image : comprises a two dimensional
block of what are called picture elements with each
element represented by a fixed number of bits .
• Application involving audio and video represented
by analog signal

8. Multimedia information
representation
• In application that involve a single type of media the
basic form of representation of the particular media
type is often used .
• In the applications that involve text and images or
audio and video their basic form is often use since the
two media types have the same form of representation
• In application that involve the different media type
integrated in some way it becomes necessary to
represent all media types in a digital form.

9. Multimedia networks
• Telephone networks
• Data networks
• Broadcast television netwoks
 Cable network
 Satellite network
• Integrated services digital networks(ISDN)
• Broadband multiservice networks (B-ISDN)
 ATM
 Frame Rely

10. Multimedia applications
• A Multimedia Application is an Application which
uses a collection of multiple media sources e.g. text,
graphics, images, sound/audio, animation and/or
video.
• They can be placed into one of three categories :
 Interpersonal communications
 Interactive application over internet
 Entertainment applications

11. Interpersonal Communications
Speech only :
 Telephony
• Provided using PSTN/ISDN/cellular phone network.
• User can take part in telephone calls through the PC.
• This required computer telephony integration (CTI)
 Voice mail:
• Spoken message is left in voice mailbox located in
voice mail server.

12. Interpersonal Communications
 Teleconferencing calls:
• Multiple interconnected telephones/PC.
• Each person can hear and talk to all of the others
involved in the call.
 VoIP:
• Telephony over the internet is also known packet
voice

13. Interpersonal Communications
Image only:
• Exchange of electronic image of document Over
PSTN / ISDN .
• This simply known as fax.
• To send a document the sender keys in the telephone
number of intended recipient and a circuit is set up
through the network in the same way as for a
telephone call.

14. Interpersonal Communications
Text only :
• An example is electronic mail over the internet.
• Associated with each network is a set of one or more
server computers (e-mail server) that contain a
mailbox for each user.
Text and image
• An example is computer-supported cooperative
working (CSCW) .
• A distributed group of people –each in his or her
place of work-are all working on the same project.

15. Interpersonal Communications
• A window on each person’s display is used as a shared
workspace/ whiteboard.
• The display comprises text and images integrated
together.
• The software associated with CSCW comprises a central
program known as whiteboard program that is made up of
tow parts: a change notification part and an update control
part.
• Whenever a member of the group updates the contents of
his or her white board, the change notification part sends
details of the changes to the whiteboard program.

16. Interpersonal Communications
• This relays the changes to the update control in each
of the other PCs which in turn proceed to update the
contents of their copy of the whiteboard.
 Speech and video
• An example is video telephoning
• Supported by all the networks types.
• The terminals incorporate a video camera,
microphone and speaker.
• The integration of the video with speech requires
more bandwidth than that required for speech only.

17. Interpersonal Communications
• A call may involve several people (a desktop
videoconferencing).
• A separate window on the screen of each participant’s
PC should be used to display the video image of all
the other participants.
• This would require multiple integrated
communication channels, one for each participant.
• In case of enterprise network, In order to support
videoconferencing there is a central unit called
multipoint control unit(MCU).

18. Interpersonal Communications
• Alternatively networks such as LANs and the internet
support multicasting. Thus MCU is not required.
• There are applications that involve groups of people
at one or more of the locations such as remote lecture
and group video conferencing .
• Remote Lecture has similar requirements to those for
two party video call .
• If the lecture is being relayed to multiple locations
either a separated channel is require to each remote
site or an MCU is used .

19. Interpersonal Communications
• In the case of group videoconferencing , an equipped
room called a videoconferencing studio is used .
• videoconferencing studio contains all the necessary
audio and video equipment : video camera , large
screen display , and associated audio equipment all of
which is connected to a unit called videoconferencing
system.
• A conference can involve two locations and or more .
• In the case of the later, an MCU is used.

20. Interpersonal Communications
Multimedia
• An example mail that containing many types media type :
• Voice mail:
• Internet based voice mail
• In addition to e-mail server there is also a voice mail
server associated with each network .
• Multimedia mail
• The textual information is annotated with a
digitized image , speech or video.

21. Interpersonal Communications
• The annotation can be sent together with
original textual message and hence stored and
played out in the normal way.
• Alternatively The annotation can be requested
by the recipient when the textual message is
being read.

22. Interactive applications over the
internet
Web server
• The internet is used to support a range of interactive
applications , the most widely used being for
interaction with World Wide Web (WWW) or simply
Web server .
• Web server comprises a linked set of multimedia
information severs that distributed around the
internet .
• The information stored on all servers is equivalent
to a vast library of document .

23. Interactive applications over the
internet
• Each document comprises a linked set of pages and
linkage between these pages known as hyperlinks .
• Hyperlinks references either to other pages of the
same document or to any other document within the
total Web.
• Document comprising only text are created using
what is called hypertext , while those comprising
multimedia information are created what is known as
hypermedia .

24. Interactive applications over the
internet
• Each document has a unique address – known as a
uniform resource locater (URL) .
• URL identifies both the location of the sever on the
internet where the first page of the document is stored
and the file reference on that sever .
• The first page of the document is known as home
page .
• A standard format is used for writing documents

25. Interactive applications over the
internet
• This known as hypertext markup language (HTML)
• HTML is also used to write client software to explore
the contents of the Web.
• The client function is called browser .

26. Entertainment applications
Movie or video on demand
• Video and audio on demand associated with
entertainment must be of higher quality / resolution.
• A digitized movie/video - with sound – requires a
minimum channel bit rate (bandwidth) of 1.5 Mbps.
• The network used to support this type of application
must be either a PSTN with high bit rate modem or
cable network.
• A collection of digitized movie/video stored on a
server .

27. Entertainment applications
• Subscriber terminal comprises a television with a
selection device for interaction purposes .
• The user interactions are relayed to the server through
a set up box .
• A key feature of video / movie on demand is that a
subscriber can initiate the showing of the movies at
any time of the day or nigh .
• This means that the server must be capable of playing
out simultaneously a large number of video streams
equal to the number of subscribers currently watching
a movie .

28. Entertainment applications
• If the server is supporting large number of subscribers
, then it is common for several subscriber to request
the same movie within a short time interval between
each request .
• An alternative mode of operation is near movie on
demand (N-MOD)
• In N-MOD requests for a particular movie are not
played out are queued until the start of the next play
out time of that movie .

29. Entertainment applications
• In this way , all request are satisfied simultaneously
by the server outputting a single video stream.

30. Entertainment applications
Interactive television
• By connecting appropriate terminal equipment to the
STB – a key board , telephone and so on – the
subscriber is able to gain service provided through the
PSTN .
• Then the subscriber is able to actively respond to the
information being broadcast.