 on and off. See CD-ROM. companding Like 'codec' or 'modem,' companding is a contraction, in this case, combining the words compressing and expanding. It refers to the reduction of the dynamic range of an audio or video signal in which the signals are sampled and transformed into non-linear codes. component video Transmission and recording of color television with luminance and chrominance (red, green and blue picture components) treated as separate signals. Component video is not a standard but rather a technique that yields greater signal controls and image quality. Hue and saturation (chrominance) are considered a single component, as is luminance (brightness), which is recorded at a higher frequency than chrominance; this makes it possible to exceed 400 lines of resolution. Component video is also known as Y/C. In component video, synchronization information may be added with the G signal; it can also be a separate signal. composite video A color television signal in which the chrominance signal is a sine wave that is modulated onto the luminance signal that acts as a subcarrier. This is used in NTSC and PAL systems. compression The process of reducing the information content of a signal SO that it occupies less space on a transmission channel or storage device and a fundamental concept of video communications An uncompressed NTSC signal requires about 90 Mbps of throughput, greatly exceeding the speed of all but the fastest and shortest of today's networks. Squeezing the video information Video Communication: the Whole Picture can be accomplished by reducing the quality (sending fewer frames in a second or displaying the information in a smaller window) or by eliminating redundancy. conditional frame A process of compression in which only the changes replenishment that are present in the current video frame, when compared to the past video frame, are transmitted. conferencing The ability to meet over distance in which meetings can include both visual and audible information. Typically videoconferencing syste