standard interface between a network access device and a network. An ITU-T list of interchange circuits for connecting a terminal device to a modem or one type of communications equipment to another. Videocassette recorder-originally a trade name but now a generic term commonly used for a device that plays videotapes. Very-high-speed-digital subscriber line. vector quantization A vector is a mathematical representation of a force (in video the force is a frequency, or a series of Video Communication: the Whole Picture frequencies). In vector quantization blocks of pixels are analyzed to determine their vectors. Vectors are then used to select predefined equations that describe them in a more efficient way. These equations are expressed as codes, which might be only a few bits long. A decoder interprets these abbreviated codes and uses them to describe a frequency with a given hue and saturation. vertical blanking An interval that occurs at the beginning of each video field in which the reproducing spot is turned off during the process of retracing from the bottom right to the top left of the screen. After the vertical blanking period has ended the electron starts shooting electrons at the screen again, starting at the top and working toward the bottom. vertical resolution The total number of horizontal scan lines. vertical sweep signal The electrical signal that moves each horizontal scan line vertically. Video Graphics Array. Developed by IBM, this has become the dominant standard for PC graphics. VGA provides two different graphics modes: 640 by 480 pixels at 4-bits per pixel or 320 by 200 pixels where 8 bits are used to describe a pixel. Very High Frequency. The frequency band used to transmit television channels two through 13. video A sequence of still images that, when presented at a sufficiently high frame rate, give the illusion of fluid motion. In the US, full-motion video (TV) is sent at 30 frames per second In Europe and most of the rest of the world the frame rate is 25 per second. Motion pictures sen