te that is least twice its highest frequency). The instantaneous amplitude of each sample is expressed as one of a defined number of discrete levels. These levels can then be assigned a digital value. quantization matrix A set of values used by a de-quantizer. The H.261 quantization matrix specifies 64 8-bit values. QuickTime Apple's video compression solution developed for the Macintosh product line. Decompression can be accomplished using nothing more than standard computer hardware although QuickTime accelerator cards with hardware decompression chips allows much better results. See random access memory. Random Access Memory RAM. A storage receptacle that is volatile, i.e., that it only retains information until a computer is turned off. raster The pattern of horizontal lines that form the image scanning of a television system. raster scan The process of continually scanning both vertically and horizontally using an electron beam to create moving images on a television screen. Regional Bell Operating Company. This term is used in a general sense today to refer to any of the original 22 Bell Operating Companies that were spun off parent AT&T as part of the MFJ (pronounced R-BOK). Radio Corporation of America. First large commercial enterprise to wholeheartedly pursue television in the Video Communication: the Whole Picture US under the direction of David Sarnoff. RCA Jack A physical interface commonly used in audio and video equipment (often colored red, white, or yellow). Real-time The time that elapses when events occur naturally. This term describes computing and electronic applications in which there is no perceived delay in the transmission of an interactive communication. Real-time compression Capture and compression of video in one step SO that it can be written to disk or other storage media. Real-Time Transport RTP adds a layer to IP to address problems caused Protocol when interactive multimedia communications are transported over TCP/IP networks. Packet-switched networks were designed for data in whi