Managing Interactive Media Glossary: D

Glossary: D (41 entries found)

DAT: Digital Audio Tape, an obsolescent format using 4 mm tape in cassettes origin-ally designed for digital audio (48 kHz sampling 16 bit) but also used to store data when it operates as a streamer tape format, when it is called DDS. Being replaced by hard disc and memory-card recorders.
data protection: The concept in European law whereby personal information is protected and the organizations who use this data and the use they can make of the data are registered and regulated. See also safe harbour.
DCT: Discrete Cosine Transform, a mathematical technique for transforming a bit map of an image, which contains individual dots of the image from left-to-right and top-to-bottom. The DCT analyses the image block by block to find the large areas of colour and the fine detail in them. The resulting file can then be analysed to determine what can be removed without seriously affecting the look of the image. This is the basis of JPEG and the first stage of MPEG compression.
DDS: Digital Data Storage, data format that uses DAT tapes.
debug: To study an application with the intention of removing any errors found.
deck: The equivalent of a website in WAP. The analogy is a deck of cards.
decompile: To take the machine code version of a program and change it back into something a human can understand.
decryption: To remove the encryption from something so that the original is produced.
delivery medium: The system used to distribute an application. The World Wide Web can be considered to be a delivery medium.
delivery platform: The multimedia system or systems that people will use to interact with the application. The total specification of the platform is important so that the application is developed within the capabilities. A web browser can be considered to be a delivery platform.
design brief: Usually a document - but may be oral instructions - produced by clients for developers to describe the outcomes they expect from a project.
development platform: The multimedia system that is used to develop the application. This may not be the same as the delivery platform. It is important that the final application is tested on the delivery system to check that it will perform on the specified platform.
development testing: This is iterative testing applied naturally during the development of a project to ensure that all the pieces work.
diaphragm: In a microphone, the membrane that is vibrated by sound and so causes the production of an electrical signal that represents the sound.
digital: In a digital system, the signal (including such things as sounds and pictures) is turned into a series of numbers, and it is these numbers that are stored or transmitted. In an analogue system the signal itself is either stored or transmitted directly, or is converted into another medium that can follow its variations and itself be stored or transmitted. Whereas analogue systems are prone to distortion and noise, digital systems are much less susceptible, although such degradation is likely to lead to total failure.
direct competitors: Companies that are in the same line of business, competing for sales from the same people.
direct marketing email: Emails sent to lists of addresses informing people about products or services. These may be solicited or unsolicited emails. See also spam.
discovery learning: A learning situation that is structured to allow the learner to explore and find answers rather than simply being given the information.
distance learning: A learning situation in which the student studies a course away from the institution using any medium that is provided. This may include interactive programs. See also open learning centres.
distribution channel: A well-defined and sustained system for moving goods from production out to the people who will buy the products.
dither: Small, seemingly random perturbations to a signal or image designed to fool the eye or ear into thinking that it has greater quality than it really does. In graphics a dither is a seemingly random pattern of dots of a limited range of colours that, when viewed from a distance, appears to have a greater range of colours. When digitizing a signal a dither is used to reduce the effect of digitizing errors because our eyes and ears are less distressed by noise (which dither looks like) than by the sharp changes in a signal that the dither disguises.
DLT: Digital Linear Tape, a streaming tape format used for data backup and also used to send DVD masters to replication facilities. Replaced exabyte and DAT for these purposes where large quantities of data are involved.
document-based programming: Programming in which the format of the document is standardized and one or more applications can be used in concert to read or display it. The World Wide Web is an example of this.
Dolby: The company (and inventor) famous for a system for reducing noise in an audio recording and for systems providing multichannel (surround) sound in cinemas and the home. The name is often used ambiguously for either. Dolby is a trade mark.
domain name: The Internet equivalent of a street address, showing the route to a particular computer. The name will end with the top-level domain name (TLD), which designates a user sector, primarily in the USA, such as .com for commercial, .gov for government or .edu for education. There are also internationally agreed country names used as TLDs such as .us, .uk, .fr and .dk, and a machine will usually be situated in that country. New TLDs are occasionally added. The US sector top-level domains are often used by organizations wishing to show an international presence even if they are based outside the USA. In an email address the domain name appears after the @ symbol. An individual computer can have a fully qualified domain name (FQDN), which uniquely identifies it. Every FQDN must have a corresponding IP address but the reverse is not true.
domain name registrar: A company authorized to sell domain names and arrange for them to be made available on the Internet.
domain name system: Usually just called DNS, this is a distributed database on the Internet that maps domain names to IP addresses and vice versa.
dot com company: Usually used to refer to a company that exists and trades solely in cyberspace. The name comes from the top-level domain where many businesses have their domain names.
dot pitch: The distance between dots of phosphor on a colour television or monitor cathode ray tube (CRT). Figures of .23-.28 mm are common, and a smaller dot pitch means a higher resolution is possible. The dot pitch of a CRT is not directly related to the resolution of the image being displayed: the actual pixels of the image usually cover several dots. This is different to an LCD where there is a one-to-one relationship between pixels in the image and pixels in the screen structure so that changing the resolution of an image involves rescaling it to fir the screen resolution required.
double byte: The use of 16 bits (2 bytes) that allows all the characters needed for all world languages to be represented in software. This includes Hindi, Thai, Chinese and Japanese, for example, and the standard for this is called Unicode. Most Western European languages can be represented in 8 bits using the standard called ASCII. See also bi-directional.
downtime: The period of time when the development team are waiting for a response or assets from the client and cannot continue with productive work until they receive these.
dpi: The density of dots in an image or on a computer screen.
draw object: In graphics, an image that is defined in terms of simple graphics 'primitives' such as lines, arcs and fills. It has no actual size, only a shape, and can be scaled cleanly.
drop frame: In NTSC television time code, a time code format which adjusts to compensate for NTSC not having a whole number of frames per second by dropping some time code numbers to keep in step.
dub: To copy something, usually an audio or videotape recording. A dub is the copy itself. In digital terminology a direct digital copy is often called a clone since it will be indistinguishable from the original.
dumb terminal: A computer terminal with a keyboard and screen that does nothing other than show a display generated at a distant computer and send back your typed input.
DVB: Digital Video Broadcasting, the system used in most of the world apart from the USA. Also a mark used on European digital televisions to show that they will receive digital TV programmes.
DVD: Digital Versatile Disc, originally called digital video disc, this is the successor to CD-ROM and has many incarnations. The capacity of a DVD disc is much greater than that of a CD-ROM because the system packs the information more tightly on the disc, has the possibility of two information layers per side and can have information on both sides of the disc. As with CD, recordable, re-writeable, audio, and ROM versions are possible. DVD Audio is one of two new formats designed to supersede compact disc audio; the other is SACD.
DVD-ROM: Use of DVD to hold a large amount of data (up to almost 18 gigabytes), which can then be accessed by a computer. Basically the equivalent of a big CD-ROM.
dynamic range: In audio, the range of loudness or volume of a sound.
dynamic web page: A web page that is composed by a program running on the web server computer based on factors such as the kind of request from the browser and what information is currently available. To the browser it looks exactly like a static page.