dictionary of multimedia and internet applications: a guide for developers and users. francis botto

Print ISBN 0-471-98624-0 Online ISBN 0-470-84178-8

I

i750 chipset A chipset initially developed by Intel for the compression and

delivery of DVI (Digital Video Interactive) video. The ActionMedia capture and playback boards for DVI video were based on the i750 chipset. Nowadays it is used to playback Intel Indeo video at high speed using such expansion cards as the ActionMedia II.

(See MMX Technology and MPEG*.)

IAP (Internet Access Provider) A company that provides users with

access to the Internet; an alternative name for ISP.

(See ISP.)

IBM (International Business Machine) A major manufacturer of business

computer systems and software products, including OS/2. Launched the IBM PC in early 1980s, which was to become an industry standard. Its successor, the PC AT, was downwardly compatible, and it too became an industry standard. Introduced the Personal System/2 (PS/2) in mid-1987, incorporating the Micro-channel Architecture (MCA) bus for the first time.

IBM ViaVoice (See ViaVoice.)

ICMP (Internet Control Message Protocol) A protocol used between

an Internet gateway and hosts. It returns error messages and reports, including:

● Unreachable destination

● Echo

● Echo reply

● Parameter problem

● Redirect

● Time exceeded

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Icon

● Timestamp

● Timestamp reply.

(See TCP/IP.)

Icon A graphical representation of an option, application or feature on

screen. Selected by pointing and clicking with a mouse, or through other means of user interaction including voice commands.

IconAuthor A popular multimedia authoring environment; it competes with such packages as Macromedia Authorware and Asymetrix ToolBook.

(See Authorware, Lingo, OpenScript and ToolBook.)

IDA (Integrated Digital Access) A digital network pilot scheme which

was introduced in 1988 by British Telecom. It was operated in Manchester and London.

IDC 1. Internet Database Connector: a Microsoft server extension, which interacts with 32 bit ODBC-compliant databases such as:

● Microsoft Access

● Microsoft SQL Server

● Microsoft FoxPro

● Oracle

● Sybase.

The IDC:

● is a DLL, and receives database requests via the Web server from the

user’s browser

● interacts with the database, and submits SQL queries ● receives resulting data from the database ● passes the data to the user’s browser via the Web server. IDC files may be created using Microsoft’s FrontPage Database Con-nection Wizard. (See FrontPage, Web* and Web server) 2. A firm of analysts specialising in IT.

IDE (Integrated Disk Electronics) A disk controller used widely on PCs,

often integrated with the motherboard. In its standard form, at least two hard disks and two floppy disk drives are supported. IDE CD-ROM controllers are also widespread.

IEEE Multimedia An arm of the Institute of Electrical and Electronics

Engineers, focusing on multimedia.

IEEE1394 (See Firewire.)

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Interactive Web Architecture

IIS (Internet Information Server) A Microsoft Web server, which forms

part of the Windows NT 4.0 Server default installation. Including FTP, HTTP and Gopher services, the IIS may be implemented to perform the standard and specialised functions of:

● downloading HTML pages to browsers ● downloading streaming audio ● downloading streaming video

● downloading streaming multimedia ● downloading files using FTP

● uploading files using FTP.

The IIS provides a migration path for the renovation of legacy systems, supporting CGI components.

(See ASP, CGI, FTP, HTTP, ISAPI and Web server.)

IMA (Interactive Multimedia Association) An organisation that provides

considerable information resources and support for multimedia pro-fessionals.

Image compression A means by which pixel data can be compressed. The

compression process may be lossless or lossy. Discrete Cosine Transform (DCT) features strongly in image compression. This has been adopted by numerous manufacturers and is the mainstay of the JPEG algorithm.

(See DCT, JPEG and MPEG-1/2.)

Image format Numerous image file formats exist for storing digital images,

including PIC, TIFF, IMG, EPS and GIF.

Image processor A processor specifically designed for image compression

purposes. Unlike a conventional processor, it is usually designed to carry out specific matrix transformations at high speed.

Immersive VR Full immersion VR places the user in a virtual world, which can be navigated and interacted with to varying degrees. Users can interact with other users. Achieving a virtual world requires the user to wear a head mount display (HMD) which normally contains miniaturised LCD screens.

(See VR.)

Inactive Web Architecture An architecture where an HTTP server is con-

nected to HTML clients (with browsers). The connection is provided by an IP network such as the Internet or an intranet. The client functionality is restricted to information browsing and the reception of HTML documents.

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Include <file>

HTTP

Server

IP network Client

Internet or intranet

Client Client

Browser

Client

Inactive Web

The information flow is unidirectional, and the client cannot edit or enter data into HTML documents. The Inactive Web model is rarely used, other than when an intranet is required for information distribution and browsing.

(See Active Web Architecture and Web.)

include <file> A C++ command which is implemented by the pre-processor and causes the contents of a named file to be read. Its precise syntax conforms to:

#include

(See C++.)

Information browsing A process of searching for and retrieving in-

formation which might be on the Internet or on a single CD-ROM or network. CD-ROM-based titles embody a retrieval engine, which is a piece of software that will accept search strings and logic operators, as well as permitting hypertext-style navigation and browsing. More modern naviga-tion and browsing tools include Microsoft Internet Explorer, Netscape Navigator and HotJava. These may be used to tour the World Wide Web (WWW or W3) using the hypertext-style model for information storage and retrieval.

(See Browser.)

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Input

Inheritance An OOP methodology where a defined type inherits the charac-

teristics of an existing type. The new type is a subclass or derived type.

(See C++, Java* and OOP.)

Inmos A chip manufacturer responsible for the innovative Transputer, a milestone in parallel processing history, and numerous other components including image compression processors and graphics chips. Once British-owned, it was bought by the European Consortium SGS-Thompson in the late 1980s.

(See Occam, MMP, NUMA and SMP.)

Inprise A software company that began life as Borland, which was

founded by Philippe Kahn in order to market and sell Turbo Pascal for the PC environment. Inprise is best known for programming tools such as Delphi Turbo C++, as well as business applications. Its headquarters are in Scotts Valley, CA. Its lesser known products include the Sprint word processor. The company was founded by Philippe Kahn, and its initial rapid growth can be attributed largely to its PC programming tools, which include Turbo Pascal. Inprise (UK) International is headquartered in Twyford, and its European headquarters are in Amsterdam.

(See C++.)

Input 1. An input device provides a means for user interaction. A key-

board is an input device, as is a mouse or remote control device. Touch-screens, track balls, joy sticks and control dials are also input devices. These were referred to as user communication devices in earlier days. 2. The process of entering data into an application. Using early versions of BASIC, such as BBC BASIC, you would enter data using a statement such as:

200 INPUT A$

210 REM * Assign the entered keyboard characters to

the string variable A$

Similarly, keyboard entries could be placed in an array using BBC BASIC with a simple loop:

10 DIM A$(2,10)

20 REM Create an array

30 REM

40 FOR X%=1 to 10

50 INPUT A$(1, X%)

60 NEXT X%

70 REM

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Input device

Input device A device used to input data to and interact with an applica-

tion or environment. Typical examples include a mouse, touchpad and touch screen.

InstallShield A tool used widely in the creation of installation programs.

(See www.installshield.com.)

Instance 1. A unit object defined by a class. It may have many running

copies or instances in an OO implementation, which may contain one or more programs in the form of executables and DLLs. (See DLL.) 2. An instance variable is the container portion of an object. This container may be used to store data. 3. A single running copy of an application. It is possible to run multiple instances of many Windows applications.

Intel A chip manufacturer founded by Gordon Moore. The world’s largest

manufacturer of PC processors, it makes the fifth generation Pentium and sixth generation Pentium Pro series of processors. Pentium processors are also available with MMX Technology, which is designed to accelerate multimedia performance. A modern fully specified PC should be con-sidered as comprising a minimum of a Pentium-class processor.

(See MMX Technology.)

Intel Indeo Video A video compression standard. The resultant video can

be played using software decompression or hardware decompression.

(See AVI, MPEG* and Video*.)

Interchangeability A generic term used to describe a peripheral device or

storage medium able to exist within more than one system type or operating system environment.

Interface device A means of connecting peripheral devices to a computer

system, consisting of hardware and software.

Interframe compression A video stream that is composed of intermittent

full frames (or intraframes) that are interwoven with partial frames. The frequency of intraframes determines the frequency of random access points for non-linear playback or editing. The partial frames sandwiched between intraframes generally contain frame information that is different from that of the intraframes. MPEG is the best known intraframe compression variant that uses what were specified as Intraframes or I frames. In MPEG compressed video streams partial frames can exist as Predicted frames or Bi-directional frames. A principal disadvantage of interframe compression

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Internet

is that it does not lend itself to non-linear editing. It also results in higher compression ratios than can be achieved using intraframe compression.

(See MPEG*.)

Interlaced A mode of operation in which the image on a monitor screen is

generated by scanning even and odd numbered lines using two separate fields. This technique was introduced in television broadcasting specifically to optimise transmission bandwidth and reduce screen flicker. However, it can generally be assumed that a monitor operating in interlaced mode presents an image that flickers considerably more than a non-interlaced monitor.

(See CRT and Monitor.)

Internet A technical definition might be: a global network of computer

networks. Conceptually, however, the Internet is much more, and it has become a universal publishing, distribution, real-time communications and broadcasting medium. It can also be used to gather information from users. The World Wide Web (or Web) is seen as a mainstay of the Internet, and it presents users with a hypertext navigation scheme. This now offers stream-ing multimedia playback, and may include streaming video, streaming WAV audio, graphics, photographic quality images and text. The growing number of day-to-day Internet applications include:

● e-mail

● information browsing

● downloading and uploading files to and from FTP (File Transfer

Protocol) sites

● e-commerce

● distance learning

● low-cost Internet telephony

● publishing information through personal home pages ● videoconferencing

● radio broadcasting

● Web TV (television broadcasting).

Access technologies include:

● POTS

● ISDN

● Cable

● GSM.

Cyberspace is another term for the Internet. The Internet is a fast-evolving multimedia medium that is able to combine increasingly sophisticated still images, audio and video. Moreover, the Internet is cultivating an improved

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Internet 2

real-time identity. This provides a gateway to numerous applications in-cluding telephony, videotelephony, videoconferencing, and radio and tele-vision broadcasting. Continuing evolution of the Internet will see:

● increasingly sophisticated still images, audio and video ● a growing number of Web sites used to deploy information and services,

along with qualitative improvements

● improving search engine architectures that users access in order to find

and retrieve Web pages

● faster access technologies. These include cable, ISDN and the increasing

speed of conventional modems that offer 56.6 Kbps speeds ● improved software interfaces with the Web through better browser

designs, which are programs that permit users to interact with Internet ● faster client systems such as PCs. (See Web.)

Internet 2 A high-performance Internet implementation, which is currently the preserve of US academic establishments.

Internet 3 A high-performance Internet implementation which is

currently under construction in the USA.

Internet Engineering Task Force (IETF) A publisher, originator and

certifier of specifications of Internet protocols such as TCP/IP. Further information can be obtained at www.ietf.cnri.reston.va.us.

Internet Explorer A market-leading Web browser from Microsoft, which

supports:

● ActiveX

● VBScript

● JScript

● Just-in-Time compiler for Java Applets ● SSL 2.0/3.0

● PCT 1.0

and runs on Windows 3.x/95/98/NT and Macintosh. Explorer records visited pages using a cache called the History folder. This optimises performance, as the cache is checked prior to connecting to remote Web sites. The period of time that Explorer maintains the pages within the History folder can be defined.

(See ActiveX*, Browser, JScript, PCT, SSL and VBScript.)

Internet Information Server (IIS) (See IIS.)

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Internet telephony

Internet Locator A Windows NT-based server which is part of the MCIS.

It permits users to search a database of current visitors to a Web site, and to chat with them using Microsoft NetMeeting.

(See Chat, IRC and MCIS.)

Internet relay chat (See IRC.)

Internet Society A publisher of Internet statistics and market research.

Internet telephony A method of making telephone calls using packet-

switched IP networks. In 1997 low-cost Internet telephony began to change the face of telcos, Internet Service Providers (ISPs) and corporations; the largely unregulated Internet became interwoven with telephony. For the first time ISPs could mine revenue-rich long-distance and international call businesses, which were once the preserve of telcos like BT and Mercury. Corporations and government departments may also ‘toll bypass’ the telcos by using Internet telephony over their own networks such as intranets, and significantly reduce their operating costs in the process. Similarly, since VocalTec launched the Internet Phone in 1995, growing numbers of ISP subscribers have been making long-distance and international calls for the cost of a local phone call. Internet telephony theoretically means that an ISP could become an international telco. The domestic long-distance call business presents ISPs with one opportunity to compete with telcos, as does

Internet

IP Network

ISP

Access technology

- analogue modem

- ISDN

- ATM ISP- ADSL

- cable modem

- GSM

- PC

Client Client - MAC

- NC

- Web Browser

- Internet telephony hw/sw

Internet telephony

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Interpreted

the international call business. The technology is also being embedded into the existing switched network, where it will become transparent to the user. The successful proliferation of Internet telephony also hinges on emerging internationally agreed standards, such as H.232, which collectively will unify ISP services globally. The corporate sector will also be affected by Internet telephony, with companies like Lucent technologies and Bay Networks providing turnkey solutions that integrate into existing networks. According to an IDC report, 35 per cent of medium to large companies today already have an intranet. By 1998 that is going to increase by a further 25 per cent, and by the year 2000, 80 per cent of all companies are expected to be using an intranet. With tour de force Internet telephony products, Lucent Technologies is already working with numerous corporations and an undisclosed ISP in Australia. Its products are currently used by five of the seven largest banks in Australia, and the telcos MCI, GTE and France Telecom continue to evaluate its technology. One school of thought indicates that telcos have large margins in international traffic while ISPs have small margins. It follows, then, that when Internet telephony reaches critical mass, telcos will react strongly, with falling international call prices.

(See Web.)

Interpreted A computer language in which object code is generated from

source code each time a program is run. Almost all inexpensive micro-computers of the 1980s included BASIC interpreters. Even the first IBM PC XT included a basic interpreter, which was stored as a firmware pack-age. The error message ‘Missing Basic Interpreter’, occasionally seen on later PCs, was a legacy of its earlier inclusion.

Interpreter A program which interprets a language.

(See Interpreted.)

Intraframe A key or reference frame in an MPEG video sequence. It is a full frame and does not depend upon other frames for its data. An MPEG sequence composed entirely of intraframes is termed editable MPEG because it provides random access points. Intraframes are compressed in a similar way to JPEG images, and a comparable compression ratio is achieved.

(See MPEG*.)

Intraframe compression A video stream that can be assumed to be

composed of full frames. M-JPEG is an example of intraframe compression. Its main advantage is that the resultant video files lend themselves to non-linear editing. It can also result in higher video quality than interframe compression, but compression ratios are a great deal less.

(See MPEG*.)

160

IP address

Intranet An IP (Internet Protocol) network based on Internet technology

which is confined to selected users. Firewalls serve to partition intranets and networks from the wider Internet. Initially intranets were used for publishing internal documents in large organisations. Increasingly they are being used for transaction processing, and are displacing, and coexisting with, traditional client/server and mainframe (or legacy) systems. Intranets are based on Internet technologies, including the same protocols, client devices, server-side components etc.

(See Firewall, Security and Web.)

IP (Internet Protocol) 1. A collection of standard protocols used on the Internet and compliant networks. The standard IP protocols include:

TCP (Transmission Control Protocol).

ICMP (Internet Control Message Protocol).

UDP (User Datagram Protocol).

(See TCP/IP.) 2. A standard protocol initially developed to transmit TCP (Transmission Control Protocol) segments between different networks. (See ARPANET.)

IP address A physical IP address consisting of 32 bits, which identifies a

network and its connected computers. The syntax for such addresses con-sists of four bytes, each written in decimal form and separated by a full stop:

118.234.98.87

Internet

Class C Class B Class A

Network Network Network ≤253 hosts ≤65 536 hosts ≤16 777 216 hosts

Class A, B and C addresses

IP address class A 16 24 A networks may have between 2 (65 536) and 2 (16.7

million) hosts.

Bits

0 9 32

0 netid hostid

Class A address format

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IP multicast

IP address class B 8 16 B networks may have between 2 (256) and 2 (65 536) hosts.

Bits

0 17 32

1 0 netid hostid

Class B address format

IP address class C C networks may have up to 253 hosts, and not 255 because

two values are reserved.

Bits

0 17 25 32

1 1 0 netid hostid

Class C address format

The addresses consist of a network address (netID) and a host address (hostID). The leftmost digits represent the netID address. This is set to zero when addressing hosts within the network.

(See Subnet.)

IP multicast An IP addressing system, which is known as class D and was

developed at Xerox PARC. A multicast packet addresses a multicast group of nodes or hosts. The first multicast tunnel was implemented at Stanford University in 1988.

(See Mbone.)

IPv6 (Internet Protocol) An advancement of the IP protocol which introduces 128 bit addressing and other improvements. The scaling of IPv4 32 bit addressing to 128 bit is intended to accommodate the future growth of the Internet in terms of the growing number of network addresses. IPv6 is also called IPng (IP Next Generation), and is specified by the Internet Engineering Task Force (IETF). IPv6 supports addressing of the types:

● multicast, which connects a host to multiple addressed hosts ● unicast, which connects a host to a single other addressed host ● anycast, which connects a host to the nearest of multiple hosts. (See IP address.)

IRC (Internet Relay Chat) A means of communicating using text in real

time across the Internet. The emergence of Internet Relay Chat or IRC in the late 1980s started a quiet revolution in the way people communicated

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