A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #

Glossary

Access control

A means of protecting computer data from unauthorised access.

Active matrix

A controller which allows the brightness and colour of every pixel on an image.

ADSL

An Asymmetrical Digital Subscriber Line can transmit at speeds of up to 7Mbps over a single copper pair.

Algorithm

A sequential, step-by-step, problem-solving procedure that can also determine how to decompress data.

Aliasing

Also often known as ‘twittering’, this is a problem associated with interlaced video sources and affects the sharp lines and edges during camera movement, causing objects to shimmer.

ALIS

Alternate Lighting of Surfaces is a method of achieving high definition and high brightness.

Ambient light

The level of lighting present in a room other than the light emitted by a projector.

Analogue

Analogue signals are the traditional format in which audio and video are transmitted. A digital signal will usually produce a superior video quality.

ANSI

American National Standards Institute.

ANSI lumens

The degree of lamp brightness, measured in candela.

Aperture

The hole behind a lens through which light is allowed to pass.

API

Application Programming Interface is the format used by an application to communicate with an operating system.

Application

Computer software designed for a specific purpose, from sending emails to viewing videos.

Archive

Data that has been stored in a format suitable for retrieval on demand.

ASF

Advanced Systems Format is a file format which enables digital media data to be streamed over a network. Active Streaming Format is the standard file format of WindowsMediaTM Technologies files.

Aspect ratio

The ratio of width to height of an image.

Asynchronous

Asynchronous refers to two or more signals which operate at different rates despite having the same nominal rates. ATM (Asynchronous Transfer Mode) is the CCITT standard for cell relay, where information for multiple types of services, including voice, vi

ATM layer

This refers to the layer within the ATM protocol stack for routing and processing activities, including building the ATM header, payload identification, header validation and cell reception, cell routing using CPIs and VCIs, cell multiplexing and de-multi

Attenuation

The loss of signal in a transmission system.

Audio in and out

Connections for external amplifiers and speakers to allow sound output.

Authoring systems

Entry level software solutions that help users develop interactive multimedia packages, particularly suited to training and education.

Auto balance

Automatic correction of errors in colour balance in black and white areas of an image.

AVI

Audio Video Interleave is a digital file format for developing and storing sound and video.