|
|
- Back to Glossary -
|
|
- A -
Analog - waveforms, with valleys and ridges, referring to the natural form of sound/audio. To store/playback on a computer, analog data is converted to digital data.
- Anti-aliasing - Process used to remove jagged edges in computerized graphics.
- .AVI (Audio Video Interleaved) - Windows format for saving video with sound.
- B -
Bandwidth - the width of the band over which frequencies are transmitted. A band is a portion of the electromagnetic spectrum, defined by the lowest and highest frequencies in it. The bandwidth is the difference between the highest and lowest frequencies. The greater the bandwidth, the greater the carrying capacity. The Federal Communications Commission allocates portions of the band. For example, the band for VHF television broadcast is defined from 54 to 88 million cycles per second. And, of course, the band contains many "channels".
.BMP- bitmap file; the official file format for Microsoft Windows images. BMP is an RGB-only format; it supports Indexed 256 colors, Grayscale and 24-bit RGB documents; does not support CMYK documents.
- C -
.CDR - a vector graphics file format from an illustration package CorelDraw. Generally, graphics created in the .CDR format needs to be exported as a .TIF or .JPEG file in order to be used in any authoring software.
CODEC - program/device that COmpresses/DECompresses digital video.
Compression - Process that reduces the number of bytes required to store/transmit digital video. Typical schemes involve comparing frames and coding-out, or eliminating, inter-frame and intra-frame redundancies. The compression may be done by software, hardware or a combination of the two. On playback, the data is decompressed. (see also: CODEC).
Why compress video data? To reduce storage space and to playback faster. A full-screen (640 x 480 pixels) image with 16.4 million colors takes up 1 Mb of memory. For full-motion, the computer needs to display 30 pictures/frames per second, thus requiring it to "shuffle" 30 Mb of data every second. Storing 10 seconds of video would require 300 Mb.
Compression, Lossless - digitized video containing ALL the original video information.
Compression, Lossy - digitized video which, to save space, does NOT contain all the original video information.
Cross-platform - Files usable/executable with different operating systems. For example, Virtus WalkThrough, a 3-D animator program, can produce "cross-compatible" animation files for Macintosh and DOS/Windows machines. "Power" Mac's let you change to the PC work-mode; "power" PC's can handle Macintosh software/files.
- D -
Data Projector - used to project a computer’s image onto a screen. Commonly used in conjunction with a presentation graphics program such as Microsoft’s PowerPoint. (see also: DLP, InFocus projector, PowerPoint, Presentation Graphics Program).
Digital - patterns of on's/high-voltage (1's) and off's/low voltage (0's) that can be processed by a computer.
Digitalization/Digitized - process of converting video or audio signals normally in waveform (analog), into 1's and 0's.
DLP - Digital Light Projectors. (see also: Data Projector, InFocus Projector, PowerPoint, Presentation Graphics Program.)
Document Camera - a camera used to take digital images of documents/transparencies to be projected on a screen using a data projector. This technology serves the purpose of, and will eventually replace, standard overhead projectors.
DVD (digital video disc or digital versatile disc) - a new standard for recording video on CD-ROM's using MPEG2, thus boasting better-than-broadcast TV quality. Costing about the same as a CD, DVD-ROM's hold 8 to 40 times more data. Sony/Phillips and Toshiba/Time, the two major developers, predict DVD will replace videocassettes, laserdiscs, CD-ROM's and audio CD's. Recently (June '97) Hitachi announced a re-writable DVD, which may spell the end to re-writable CD's.
- E -
Elmo - popular brand of document camera. (see also: document camera)
Ethernet - network access system using the Carrier-Sense Multiple Access with Collision Detection (CSMA/CD) access method in which nodes may transmit a signal at any given time, and if two devices transmit at the same time both devices will wait a random period of time before attempting to resend.
- F -
Fiber-optic cable - type of cable used to connect devices on a network. Made of plastic or glass fibers covered with an opaque sheath. Digital signals are sent via code pulses of light. These cables are fast, reliable, and have extremely wide bandwidth.
File Transport Protocol (FTP) - a method for retrieving files from a remote Internet site. Many sites out there allow what is termed an 'anonymous' connection. In other words, there exists a special username called 'anonymous' so that the site can act as a library of useful public domain programs and documents.
Firewall - used in networking to prevent unauthorized users on the Internet from reaching the files and programs on the local area network.
Firewire (IEEE-1394) - emerging serial interface technology that allows connection of devices at speeds up to 50 Mbytes/s. Used for devices such as video cameras so that they can feed real time video to a computer. Also allows devices to be hotswapped (added and removed without rebooting).
FPS - frames per second - the number of picture images displayed per second, giving digital video the illusion of motion. Full-motion video, with no dropped frames, is considered 30 fps.
Frame - a single picture in a computerized "movie"/digital video.
Frame rate - number of images per second displayed in a stream of video.
Full-motion video - digital video running at 30 fps. It does not necessarily fill the screen.
Full-screen video - digital video filling the entire screen.
- G -
.GIF (Graphic Interchange Format) - is a CompuServe's Graphics Interchange Format - the industry standard for Web pages. GIF files support only 8-bit, or 256 colors. GIF files use LZW compression which is referred to as lossless compression - the images stay true when compressed. Most frequently the GIF file format is used for cartoons, line-art and flat illustration (this file format preserves sharp edges, as opposed to the JPEG file format). GIF is the only file format which allows for transparent images (the file contains a header with the information which color in the image is invisible).
- H -
HDTV - High Definition Television. Because of the larger picture size (16-by-9 display ratio for HDTV versus 4-by-3 for regular TV) and more horizontal picture lines, HDTV will have a higher quality display than conventional TV. Also, HDTV has cd-quality sound and involves digital transmission instead of analog.
HI8 (high-band 8mm) - Improved version of 8mm videotape format characterized by higher luminance resolution for a sharper picture. Compact "conceptual equivalent" of Super-VHS.
- I -
Image File Formats - .BMP, .GIF, .JPG, .TIFF, .PICT, .CDR
InFocus Projectors - brand of data projector used by Multimedia Services. (see also: Data Projector, DLP, Presentation Graphics Program, PowerPoint).
IP - Internet Protocol (IP) - the protocol which provides addresses needed to move packets of information across networks. IP addresses have two parts: a network identifier and a host identifier.
IP Conferencing - video conferencing using IP networking.
ISDN (Integrated Services Digital Network) - a network/telephone connection that transfers data at rates more than 4 times faster than a 28.8Kbps modem. Ordinary modems (non-ISDN) convert computer data to audio tones/analog to transfer over the phone lines. ISDN "modems" connect digitally: Inherently faster digital signals rather than tone signals transfer over the lines. Basic Rate ISDN, often called "2B+D" or RI, arrives on 3 channels - one Delta ("D") 16 Kbps channel carrying telephone signals and two "Bearer" ("B") channels delivering data at 64 Kbps. Primary Rate ISDN, also known as T1 service, has 23 B channels and one D channel, delivering at a rate of 1.544 Mbps (T3 transmits at an extremely high rate - 44.7 Mbps).
ISDN Conferencing - video conferencing using ISDN lines rather than IP.
- J,K -
.JPG, .JPEG (Joint Photographic Experts Group) - compressed, still-image graphics files. There are two major types of JPEG - progressive, where a fuzzy images emerges into 100% decompression/clarity, and baseline or standard, where a clear image is revealed, part-wise, top-down. Progressive, or interleaved, decompression looks better over networks.
- L -
LAN (Local Area Network) - A privately-operated communications system interconnecting computers and communications equipment over a limited geographic area, usually 5 miles or less. LAN's enable local resource -sharing (printers, files, etc.).
Line Level - A signal level between -10dBu and +30dBu. CD players, VCRs, surround processors, and most recording devices are connected to a system at line level (before power amplification).
Live Feed - real-time continuous broadcast.
Luminance - a color's brightness.
- M, N -
Mic Level - The typical level of a microphone signal. Usually lower than -40 dBu.
.MOV - see: QuickTime
MPEG (Motion Picture Experts Group) - a developing standard for digital video compression used to send movie files for viewing on the World Wide Web. The MPEG file name extension is either .mpeg or .mpg. (see also: CODEC)
Multimedia - the combined use of several media, such as high-quality graphics, animations, and sound.
Mulitpoint Videoconferencing - videoconference allowing three or more participants to sit in a virtual conference room and communicate as if they were sitting right next to each other.
- O -
On-Demand Feed - playback of a previously recorded session during which the viewer/listener can fast-forward, back up, or pause.
- P -
.PICT - it's a standard image format for Macintosh; it was designed as both a vector and bitmapped image format. PICT is not efficient for storing large documents (10Mb or larger).
Pixels - PICture ELements = Pixel. The tiny dots comprising a picture.
Point-to-Point Videoconferencing - videoconference between two participants.
PowerPoint - Microsoft presentation graphics program used frequently at NCAR. (see also: Presentation Graphics Program, Data Projector, InFocus Projector, DLP).
Presentation Graphics Program - allow end-users to put together multimedia shows for presentations, meetings, lectures, and special events. (see also: PowerPoint, Data Projector, InFocus Projector, DLP).
- Q -
QuickTime (.MOV) A Cross-Platform real-time video and multimedia data format developed by Apple Computer. QuickTime files can include text, sound and video.
- R -
RCA - Also called "phono plug" or "RCA phono," popular cable connector for home audio as well as video components. Standard connection for direct audio/video inputs/outputs. Not to be confused with phone plug.
RealAudio - real-time, live audio on the Web. RealAudio highly compresses sound files to ship down the network. After front-loading a portion of the recording, the receiving player starts, pulling in remaining portions. This lets users begin listening as the sound file is being downloaded, hence "real-time", rather than having to wait until downloading is complete.
RealVideo - delivers "broadcast-quality" video over the Internet in real-time. The software operates over modems operating at 28.8 Kbps and up.
Resolution - the clarity of the displayed/printed image. The more pixels/dots per square inch (dpi), the finer the detail (higher resolution).
- S -
Scanconverter - an adapter card used to convert a computer’s digital signal to the analog signal needed as input in a TV. Used to display the computer’s image on a standard television set.
Sound card - An add-in circuit board that once installed, enables the computer to accept audio input from a microphone, edit/trim/mix recordings, play sound files stored on disks or CD-ROM's, and produce audio output through speakers or earphones. For output, sound cards can 1) create or synthesize sounds, like a keyboard/synthesizer, and 2) play previously-recorded sounds, like a tape recorder/player.
Streaming Audio/Video - capability to begin playing media on the client side before it has fully downloaded from the server side, i.e. begins playing as it is coming in, " in real-time."
Subnet - A portion of a network that shares a common address component. On TCP/IP networks, subnets are defined as all devices whose IP addresses have the same prefix. For example, all devices with IP addresses that start with 100.100.100. would be part of the same subnet. Dividing a network into subnets is useful for both security and performance reasons.
SVGA (Super-VGA) - a set of graphics standards designed to offer greater resolution than VGA.
S-VHS - video format of superior quality to standard VHS. (see also: Video, Component).
- T -
10base-T - type of cable used to connect devices on a network. 10base-T uses a twisted pair cable (similar to a phone line).
10base-2 - type of cable used to connect devices on a network. 10base-2 uses coaxial cable that is thinner than TV cable.
TCP/IP- "Transmission Control Protocol/Internet Protocol"; a set of communication standards through which different kinds of computers on the Internet communicate together; the "language" of the Internet. (see also: IP)
Teleconference - a phone meeting where callers can both see and hear each other. (see also: Video Teleconferencing)
.TIFF (Tagged Image File Format) - general purpose file for bitmapped graphics; developed by Aldus Corporation; in general it can handle any type image. Usually the .TIF documents are 24-bit graphics images.
- U, V -
Vector Graphics - Images composed of sets of graphical objects (lines, rectangles, ellipses, arcs, curves, etc.) stored by software as numerical coordinates and mathematical formulas specifying their shape and position in an image.
VGA (video graphics array) - VGA systems provide a resolution of 720 by 400 pixels. In graphics mode, the resolution is either 640 by 480 (with 16 colors) or 320 by 200 (with 256 colors). The total palette of colors is 262,144.
Video, Analog - True full-motion video from laser discs, videotapes. Formats: Hi8, 8mm, S-VHS, VHS.
Video Capture Card - adapter card which allows recording and digitalization of pictures for use with a computer. The pictures may be still-images or movies. Once captured, the picture data is compressed using a CODEC, with playback requiring CODEC-decompression. (see also: CODEC)
Video, Composite - single-signal video, used in VHS. Inferior to component video.
Video, Component - Used in Hi8 and SuperVHS cameras, component video splits the single composite video signal into colors (RGB) and improves the quality by adding a luminance or brightness (Y) channel and a color/chroma intensity (C) channel. Superior to composite video.
Video, Digital - Digitized video, i.e. video converted/compressed to file format. Formats: .AVI (Video for Windows) and .MOV (QuickTime - cross-platform for both Macintosh and Windows).
Video Teleconferencing - transporting real-time voice and video over telecommunications services.
- W,X,Y,Z -
WAN - Wide Area Network
.WAV - WAVE file. The most common file format for Windows sounds.
Webcasting - using the Web to deliver live or delayed versions of sound or video broadcasts.
Whiteboard - teleconference function that lets multiple users simultaneously view and annotate electronic documents with pens, highlighters and drawing tools.
XGA (extended graphics array) - a high-resolution graphics standard introduced by IBM in 1990. It provides 640 by 480 or 1024 by 768 and supports more simultaneous colors (65 thousand compared to 8514/A's 256 colors). In addition, XGA allows monitors to be non-interlaced.
XLR Connector - A 3 prong connector commonly found on microphones.
- Sources -
- Back to Glossary - Word Suggestions, questions or comments on this web page. -
- Copyright©2000 -
This page last updated: 22 March 2000
