Bibliographic Management | Factfile

Digital media

A variety of content can be recorded in digital format: text, maps, still and moving images, sound, and datasets. Depending on the type of content, one of a number of digital formats is used to store the data. A variety of carriers are used to hold the digital (or digitised) content.

Formats

• Text
• Audio
• DAISY
• Image
• Datasets

Carriers

• Optical disc
• Magnetic tape

Formats

Text

Text can be held as simple ASCII files, or in formatted word processor files (such as Microsoft Word). There are also formats for holding numerical data (spreadsheets), and slideshows for presentations.

Audio

MP3 is a digital audio encoding and lossy compression format, designed to reduce the amount of data (10:1 compression is common) required to represent audio. The name is derived from MPEG-1 Audio Layer 3.

DAISY

Digital Talking Books (DTBs) are a multi-media representation of a print publication. The audio component is a human voice. Digital talking books use the DAISY (Digital Accessible Information SYstem) standard.

Image

There are several types of image files: JPG, GIF, TIFF, PNG, BMP, etc. Image files tend to be large; compression levels and the number of colours included are among the factors that determine the size of the file. Image files can be held on servers, PCs and storage media such as floppy disks, CDs and DVDs.

Datasets

Where the data to be held consists of large numbers of facts, which are variously linked to each other, and the data needs to be interrogated, it is held as a dataset. In addition to general purpose database formats, more specialised formats have been developed for specific types of data.

Carriers

Digital content is held on computers, and is either accessed directly (the data is held on a person's own PC, for instance) or remotely (for example, the content of any web site). In addition, the data can be recorded onto storage media, either for backup or for moving data from one computer to another.

Optical disc

An optical disc is a flat, circular, usually polycarbonate disc on which data is stored. The data is usually accessed when a special material on the disc (often aluminium) is illuminated with a laser diode. Examples of optical discs are: Blu-Ray disc, Compact Disc (CD), DVD, HD-DVD, Laserdisc, magneto-optical disc and mini-disc.

Magnetic tape

Magnetic tape is an information storage medium consisting of a magnetisable coating on a thin plastic strip. It was used for general purpose digital storage, often for backup, in computer installations of the 1990s. The tape was held as a cartridge, cassette or reel.