If you are new to computer video or just want to brush up on some of the basic terms, this short glossary will help you sort out some of the often confusing technical jargon that video editors and Web streamers use. Here are a few definitions that’ll help any beginner understand the technical talk of the trade.




artifacts Unwanted visual distortions that appear in a digitized video image, such as cross-color artifacts, cross-luminance artifacts, jitter, blocking, ghosts, etc.


aspect ratio Proportional width and height of a picture on screen. Current standard for conventional receiver or monitor is four-by-three (4:3); sixteen-by-nine (16:9) for HDTV.


batch capture The ability of certain computer-based editing systems to automatically capture whole lists or "batches" of video clips from source tapes.


capture card A piece of computer hardware that captures digital video and audio to a hard drive, typically through a FireWire (IEEE 1394) port.


compression Reducing the digital data in a video frame, typically from nearly one megabyte to 300 kilobytes or less, by throwing away information the eye can’t see. JPEG, Motion-JPEG, MPEG, DV, Indeo, Fractal and Wavelet are all common video compression schemes.


digitizer Device that imports and converts analog video images into digital information and stores it on a hard drive for editing.


dissolve Image transition effect where one picture gradually disappears as another appears. Other transition effects include such elements as wipes, flips and page curls.


encoder Device that translates a video signal into a different format RGB to composite, DV to MPEG. Encoders are used to convert video files for Internet streaming.


FireWire (IEEE 1394 or i.LINK) A high-speed, two-way bus that was developed by Apple Computers. It is used, among other things, to connect digital camcorders to computers. FireWire carries digital video and audio and edit control information.


frame rate Number of video frames displayed each second. Full speed video moves at 30 frames per second. On the Internet, frame rate is dependent upon the bandwidth available and the multimedia format from which the video file is produced.


full-motion video A standard for video playback on a computer; refers to smooth-flowing, full-color video at 30 frames per second, regardless of the screen resolution.


hard disk (hard drive) Common digital storage component in a computer. For video use, hard disks need: 1) an access time of less than 10 milliseconds; 2) a sustained throughput (data transfer rate) of three Megabytes per second; and 3) a maximum housekeeping of 33 milliseconds.


nonlinear editing Digital "random access" editing that uses a hard drive instead of tape to store images. Random access allows easy arrangement of scenes in any order. Also eliminates the need for rewinding and allows for multiple dubs without loss of image quality.


rendering time The time it takes an editing computer to composite source elements and commands in its edit decision list into a single video file so the sequence, including titles and transition effects, can be played in full motion (30 frames per second).


slideshow Series of still images delivered via the Internet one after another, often with sound. Images may advance automatically or by point-and-click selection.


streaming Playing sound or video in real time as it is downloaded from the Internet as opposed to storing it in a local file first. Streaming audio or video avoids the delay entailed in downloading an entire file and then playing it with a helper application.


superimposition (super) Titles or graphics appearing over an existing video picture, partially or completely hiding areas they cover. Also PIP (picture in picture).


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