itecture discusses scalability, security, topology, capacity and other high-level attributes. artifacts Spurious effects introduced to a signal that result from digital signal processing. These effects manifest as jagged edges on moving objects and flicker on fine horizontal edges. ASCII American Standard Code for Information Interchange, a digital coding scheme that is capable of representing 256 (text) characters. ASCII is a 7-level code for asynchronous character transmission over a network. It is a universal code. Application-Specific Integrated Circuit. A chip designed for a specific application or purpose. aspect ratio The ratio of the width to the height of an image or video displayed on a monitor. NTSC and PAL television uses an aspect ratio of 4 wide to 3 high, which is expressed 4:3. asymmetrical compression Techniques in which the decompression process is not the reverse of the compression process. Asymmetrical compression is more processing- intensive on the compression side SO that video images can be easily decompressed at the desktop or in applications in which sophisticated codecs are not cost effective. asynchronous Lacking in synchronization. A method of transmitting data over a network using a start bit at the beginning of a character and a stop bit at the end. The time interval between characters may be of varying lengths. In video, a signal is asynchronous Glossary of Terms when its timing differs from that of the system reference signal. Asynchronous Transfer Mode (also known as cell relay). ATM provides a single network interface for audio, video, image and text with sufficient flexibility for handling these different media types. The ATM transport technique uses a multiplexing scheme in which data are divided into small but fixed-size units called cells. Each cell contains a 48-byte information field and five-bytes of header information for a total cell size of 53-bytes. Although it is a packet switching technique, ATM can achieve the integration of all types of traffic, including those th