What is Multimedia?
Multimedia can have a many definitions these include:
- 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, still and moving images (Video), animation, audio, and any other media where every type of information can be represented, stored, transmitted and processed digitally.
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.
Hypermedia can be considered as one of the multimedia applications.
What is HyperText and HyperMedia?
Hypertext is a text which contains links to other texts. The term was invented by Ted Nelson around 1965.
Hypertext is therefore usually non-linear (as indicated below).
 
Definition of Hypertext
- HyperMedia is not constrained to be text-based. It can include other media, e.g., graphics, images, and especially the continuous media - sound and video. Apparently, Ted Nelson was also the first to use this term.

Definition of HyperMedia
- The World Wide Web (WWW) is the best example of hypermedia applications.Multimedia Systems
- A Multimedia System is a system capable of processing multimedia data and applications.
- A Multimedia System is characterised by the processing, storage, generation, manipulation and rendition of Multimedia information.
Characteristics of a Multimedia System
- A Multimedia system has four basic characteristics:
- Multimedia systems must be computer controlled.
- Multimedia systems are integrated.
- The information they handle must be represented digitally.
- The interface to the final presentation of media is usually interactive.
Challenges for Multimedia Systems
Supporting multimedia applications over a computer network renders the application distributed. This will involve many special computing techniques -- discussed later.
Multimedia systems may have to render a variety of media at the same instant -- a distinction from normal applications. There is a temporal relationship between many forms of media (e.g. Video and Audio. There 2 are forms of problems here
Sequencing within the media -- playing frames in correct order/time frame in video
Synchronisation -- inter-media scheduling (e.g. Video and Audio). Lip synchronisation is clearly important for humans to watch playback of video and audio and even animation and audio. Ever tried watching an out of (lip) sync film for a long time?
The key issues multimedia systems need to deal with here are:
How to represent and store temporal information.
How to strictly maintain the temporal relationships on play back/retrieval
What process are involved in the above.
Data has to represented digitally so many initial source of data needs to be digitise -- translated from analog source to digital representation. The will involve scanning (graphics, still images), sampling (audio/video) although digital cameras now exist for direct scene to digital capture of images and video.
The data is large several Mb easily for audio and video -- therefore storage, transfer (bandwidth) and processing overheads are high. Data compression techniques very common.
Desirable Features for a Multimedia System
Given the above challenges the following feature a desirable (if not a prerequisite) for a Multimedia System:
- Very High Processing Power
needed to deal with large data processing and real time delivery of media. Special hardware commonplace.
- Multimedia Capable File System
needed to deliver real-time media -- e.g. Video/Audio Streaming. Special Hardware/Software needed e.g RAID technology.
Data Representations/File Formats that support multimedia
Data representations/file formats should be easy to handle yet allow for compression/decompression in real-time.
- Efficient and High I/O
input and output to the file subsystem needs to be efficient and fast. Needs to allow for real-time recording as well as playback of data. e.g. Direct to Disk recording systems.
- Special Operating System
to allow access to file system and process data efficiently and quickly. Needs to support direct transfers to disk, real-time scheduling, fast interrupt processing, I/O streaming etc.
- Storage and Memory
large storage units (of the order of 50 -100 Gb or more) and large memory (50 -100 Mb or more). Large Caches also required and frequently of Level 2 and 3 hierarchy for efficient management.
- Network Support
Client-server systems common as distributed systems common.
Software Tools
user friendly tools needed to handle media, design and develop applications, deliver media.
Components of a Multimedia System
Now let us consider the Components (Hardware and Software) required for a multimedia system:
- Capture devices
- Video Camera, Video Recorder, Audio Microphone, Keyboards, mice, graphics tablets, 3D input devices, tactile sensors, VR devices. Digitising/Sampling Hardware Storage Devices.
- Hard disks, CD-ROMs, Jaz/Zip drives, DVD, etc
- Communication Networks
Ethernet, Token Ring, FDDI, ATM, Intranets, Internets.
- Computer Systems
Multimedia Desktop machines, Workstations, MPEG/VIDEO/DSP Hardware
- Display Devices
CD-quality speakers, HDTV,SVGA, Hi-Res monitors, Colour printers etc.
Applications
Examples of Multimedia Applications include:
World Wide Web
Hypermedia courseware
Video conferencing
Video-on-demand
Interactive TV
Groupware
Home shopping
Games
Virtual reality
Digital video editing and production systems
Multimedia Database systems
Trends in Multimedia
Current big applications areas in Multimedia include:
World Wide Web
-- Hypermedia systems -- embrace nearly all multimedia technologies and application areas. Ever increasing popularity.
MBone
-- Multicast Backbone: Equivalent of conventional TV and Radio on the Internet.
Enabling Technologies
-- developing at a rapid rate to support ever increasing need for Multimedia. Carrier, Switching, Protocol, Application, Coding/Compression, Database, Processing, and System Integration Technologies at the forefront of this.
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