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

U A chrominance component in a video signal that comprises colour information.

UART (Universal Asynchronous Receive Transmit) An electronic device used for serial communications.

UDP (User Datagram Protocol.) A protocol which is used widely in streaming audio and video. Macromedia Shockwave Director 6.0 is among a number of leading streaming server technologies which use UDP. It does not feature the reliability of TCP, and is therefore appropriate for stream-ing media where intensive error detection and correction is less important. Dropped packets, which are those that do not reach their destination, are acceptable in streaming media. UDP therefore optimises performance and makes better use of available bandwidth because it does not insist on the retransmission of erroneous packets.

(See Streaming* and ASF)

UI (user interface) A software module or program through which users

interact with one or more applications.

(See GUI, OOUI and Windows.)

UI builder A development tool used to build user interfaces. Most modern UIs are OO. The resulting UIs may be text-based or graphical, as is common today. The latter naturally require the use of GUI builders, which provide a means of implementing the presentation element, together with its interaction with objects, applications and application logic. GUIs can be built using all modern multimedia authoring tools, which include Author-ware, IconAuthor and ToolBook. Programming tools such as Microsoft Visual Basic, and others included with Microsoft Visual Studio, also have the capability to construct GUIs using visual techniques. Such development

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