MULTIMEDIA: A Glossary May 14, 1992 We've assembled this glossary to help you understand Intel's meaning for many of the following words and acronyms when you find them in our materials. Much information for this glossary came from four published sources. All four are excellent publications, with more multimedia terminology and definitions than has been included here. Multimedia Applications Development Using DVI Technology, by Mark J. Bunzel and Sandra K. Morris, McGraw Hill Book Company, New York, 1992. Digital Video in the PC Environment, by Arch. C. Luther, McGraw-Hill Book Company, New York, 1991. Multimedia & Related Technologies: A Glossary of Terms, published by the editors of Multimedia and Videodisc Monitor at Monitor Information Services, (703) 241-1799. The Video Compression Glossary, by Craig Birkmaier, Videography, June 1991. (212) 779-1919. A ActionMedia(r) DVI board and software product family, jointly developed with IBM. An Intel trademark. active pixel region On a computer display, the area of the screen used for actual display of pixel information. ADPCM Adaptive Differential Pulse Code Modulation. An encoding format for storing audio information in a digital format. adaptive compression Data compression software that continually analyzes and compensates its algorithm, depending on the type and content of the data and the storage medium. additive color Color produced by "adding" colors, usually the combination of red, green, and blue. algorithm In compression software refers to a specific formula used to compress or decompress video. aliasing A form of image distortion associated with signal sampling. A common form of aliasing is a stair-stepped appearance along diagonal and curved lines. analog The representation of numerical values by physical variables such as voltage, current, etc. Analog devices are characterized by dials and sliding mechanisms. See also digital. analog video A video signal that represents an infinite number of smooth gradations between given video levels. By contrast, a digital video signal assigns a finite set of levels. See also digital video. anamorphic Unequally scaled in vertical and horizontal dimensions. antialiasing A form of interpolation used when combining images; pixels along the transitions between images are averaged to provide a smooth transition. ANSI American National Standards Institute. A standards-setting, non-government organization which develops and publishes standards for voluntary use in the United States. API Application Programmers Interface. Loosely used to describe the point at which software modules or layers meet and interconnect. artifact An unintended, unwanted visual aberration in a video image. ASCII American Standard Code for Information Interchange. The most popular coding method used by small computers for converting letters, numbers, punctuation, and control codes into digital form. aspect ratio The relationship of width and height. When an image is displayed on different screens, the aspect ratio must be kept the same to avoid "stretching" in either the vertical or horizontal direction. asymmetrical compression A system which requires more processing capability to compress an image than to decompress an image. It is typically used for the mass distribution of programs on media such as CD-ROM, where significant expense can be incurred for the production and compression of the program, but the playback system must be low in cost. audio What a human can hear. Audio frequencies range from 15Hz to 20,000Hz. authoring system Software which helps developers design interactive courseware easily, without the painstaking detail of computer programming. AVSS Audio-Video Support System. DVI system software for DOS. It plays motion video and audio. AVK Audio Video Kernel. DVI system software designed to play motion video and audio across hardware and operating system environments. B bandwidth Usually used in context to refer to the amount of data/unit of time that must move from one point to another - such as from CD-ROM to processor. bit map Representation of characters or graphics by individual pixels arranged in row (horizontal) and column (vertical) order. Each pixel can be represented by either one bit (simple black and white) or up to 32 bits (high definition color). bit-mapped graphics Images which are created with matrices of pixels, or dots. Also called raster graphics. bit specifications Number of colors or levels of gray that can be displayed at one time. Controlled by the amount of memory in the computer's graphics controller card. An 8-bit controller can display 256 colors or levels of gray; a 16-bit controller, 64,000 colors; a 24-bit controller, 16.8 million colors. bpp Bits Per Pixel. The number of bits used to represent the color value of each pixel in a digitized image. bps Bits Per Second. The number of bits transferred in a data communications system. Measures speed. brightness The balance of light and dark shades in an image. C CCITT Consultative Committee for International Telephone and Telegraph. An international standards organization dedicated to creating communications protocols that will enable global compatibility for the transmission of voice, data, and video across all computing and telecommunications equipment. CD Compact Disc. A standard medium for storaging digital data in machine-readable form, accessible with a laser-based reader. CD-I Compact Disc-Interactive. A compact disc format (developed by NV Philips and Sony Corporation) which provides audio, digital data, still graphics and limited motion video. CD-ROM Compact Disc-Read Only Memory. A 4.75" laser-encoded optical memory storage medium (developed by NV Philips and Sony Corporation) with the same constant linear velocity (CLV) spiral format as compact audio discs and some videodiscs. CD-ROMs can hold about 550 megabytes of data. CD-ROM XA Compact Disc-Read Only Memory eXtended Architecture. An extension of the CD-ROM standard billed as a hybrid of CD-ROM and CD-I, and promoted by Sony and Microsoft. The extension adds ADPCM audio to permit the interleaving of sound and video data to animation and with sound synchronization. It is an essential component of Microsoft's plan for multimedia computers. CDTV Commodore Dynamic Total Vision. Consumer multimedia system from Commodore which includes CD-ROM/CD audio player, Motorola 68000 processor, 1MB RAM, and 10-key infrared remote control. CGA Color Graphics Adapter. A low resolution video display standard, invented for the first IBM PC. CGA pixel resolution is 320x200. CGM Computer Graphics Metafile. A standard format that allows for the interchanging of graphics images. chroma, chrominance The color portion of the video signal that includes hue and saturation information. Requires luminance, or light intensity, to make it visible. CIE Commission International de l'Eclairage. The international commission on illumination. Developer of color matching systems. CMYK Cyan, Magenta, Yellow, and blacK. The four process colors that are used in four-color printed reproduction. color cycling A means of simulating motion in a video by changing colors. color keying To superimpose one image over another for special effects. composite video The complete visual wave form of the color video signal composed of chromatic and luminance picture information; blanking pedestal; field, line, and color sync pulses; and field equalizing pulses. compound document A file that has more than one element (text, graphics, voice, video) mixed together. compressed video A digital video image or segment that has been processed using a variety of computer algorithms and other techniques to reduce the amount of data required to accurately represent the content - and thus, the space required to store that content. compression The translation of data (video, audio, digital, or a combination) to a more compact form for storage or transmission. continuous tone An image that has all the values (0 to 100%) of gray (black and white) of color in it. A photograph is a continuous tone image. contrast The range between the lightest tones and the darkest tones in an image. convergence In an RGB monitor, where red, green, and blue signals all "converge" in one pixel. At full brightness, the RGB pixel in convergence would be white. CSC Computer Support Collaboration. Describes computers that enhance productivity when working in groups. Application examples include video conferencing, video mail, and shared workspaces. D DAT Digital Audio Tape. A consumer recording and playback media for high quality audio. data rate The speed of a data transfer process, normally expressed in bits per second or bytes per second. DCT Discrete Cosine Transform. A form of coding used in most of the current image compression systems for bit rate reduction. decompression To reverse the procedure conducted by compression software, and thereby return compressed data to its original size and condition. density The degree of darkness of an image. Also, percent of screen used in an image. delivery system The equipment used by end users to run or "play" on interactive program. device driver Software that tells the computer how to talk to a peripheral device, such as a videodisc player or printer. digital A method of signal representation by a set of discrete numerical values, as opposed to a continuously fluctuating current or voltage. See also analog. digital video A video signal represented by computer-readable binary numbers that describe a finite set of colors and luminance levels. See analog video. digitization Process of transforming analog video signal into the digital information. DVI(r) Intel's brand name for a variety of digital video and audio products. Current product families include the i750(r) video processor, ActionMedia(r) II boards, AVK and AVSS system software, and PLV, RTV and JPEG algorithms. Future versions of the i750 video processor will support Px64 and MPEG motion video standards. An Intel trademark. E EGA Enhanced Graphics Adapter. A display technology for the IBM PC. It's been replaced by VGA. EGA pixel resolution is 640x350. encoding The process of creating a compressed file. F field One-half of a complete video frame, consisting of every other analog scan line. filtering A process used in both analog and digital image processing to reduce bandwidth. Filters can be designed to remove information content such as high or low frequencies, for example, or to average adjacent pixels creating a new value from two or more pixels. fractals Along with rastor and vector graphics, a way of defining graphics in a computer. Fractal graphics translate the natural curves of an object into mathematical formulas, from which the image can be later constructed. frame A single, complete picture in a video or film recording. A video frame consists of two interlaced fields of either 525 lines (NTSC) or 625 lines (PAL/SECAM), running at 30 frames per second (NTSC) or 25 fps (PAL/SECAM). Film runs at 24 fps. frame grabber A device that "captures" and potentially stores one complete video frame. Also known as frame storer. frame rate The speed at which video images are displayed. full-motion video Video reproduction at 30 frames per second (NTSC-original signals) or 25 frames per second (PAL-original signals). G gain The increase in signaling power as an audio signal is boosted by an electronic device. It's measured in decibels. gradient In graphics, having an area smoothly blend from one color to another, or from black to white, or vice versa. gray scale The spectrum, or range, of shades of black an image has. H HDTV High Definition TV. A proposed standard, recommending the doubling of current 525 lines per picture to 1050 lines, and increasing the screen aspect ratio (width:height) from the current 12:9 to 16:9, which would create a television screen shaped more like a movie screen. high resolution An adjective describing improvement in image quality as a result of increasing the number of pixels per square inch. Called hi-res for short. High Sierra format A standard format for placing files and directories on CD-ROM, revised and adopted by the International Standards Organization as ISO 9660. HSB Hue Saturation Brightness. With the HSB model, all color can be defined by expressing their levels of hue (the pigment), saturation (the amount of pigment) and brightness (the amount of white included), in percentages. Hz Abbreviation for Hertz; cycles per second. I i750(r) Name of the programmable video processor family from Intel. An Intel trademark. IMA Interactive Multimedia Association. Formed in 1991 (rooted in IVIA, Interactive Video Industry Association), industry association chartered with creating and maintaining standard specifications for multimedia systems. image The computerized representation of a picture or graphic. image resolution The fineness or coarseness of an image as it was digitized, measured in Dots Per Inch (DPI), typically from 200 to 400 DPI. interactive video The fusion of video and computer technology. A video program and a computer program running in tandem under the control of the user. In interactive video, the user's actions, choices, and decisions genuinely affect the way in which the program unfolds. interlace Scheme to display a video image by displaying alternate scan lines in two discrete fields. ISO International Standards Organization. Worldwide group responsible for establishing and managing various standards committees and expert groups, including several image compression standards. ISV Independent Software Vendor. Company which develops and sells application tools and/or software titles. interframe coding Compression techniques which track the differences between frames of video. Results in more compression over a range of frames than intraframe coding. interpolation The process of averaging pixel information when scaling an image. When reducing the size of an image, pixels are averaged to create a single new pixel; when an image is scaled up in size, additional pixels are created by averaging pixels of the smaller image. intraframe coding Compression within each frame individually. Results in less compression over a range of frames than interframe coding. J JPEG Joint Photographic Experts Group. A working committee under the auspices of the International Standards Organization (ISO) that is attempting to define a proposed universal standard for the digital compression and decompression of still images for use in computer systems. L LAN Local Area Network. lossless compression Ensures that the original data is exactly recoverable with no loss in image quality. lossy compression The original data is not completely recoverable. Although image quality may suffer, many experts believe that up to 95 percent of the data in a typical image may be discarded without a noticeable loss in apparent resolution. luminance Brightness; one of the three image characteristics coded in composite television (represented by the letter Y). May be measured in lux or foot-candles. M MAN Metropolitan Area Network. MCA Media Control Architecture. System-level specification developed by Apple Computer for addressing various media devices (videodisc/videotape players, CD players, etc.) to its Macintosh computers. MCI Media Control Interface. Platform-independent multimedia specification (published by Microsoft and others in 1990) that provides a consistent way to control devices such as CD-ROMs and video playback units. Micro Channel Personal computer bus architecture introduced by IBM in some of its PS/2 series microcomputers. Incompatible with original PC/AT (ISA) architecture. MIDI Musical Instrument Digital Interface. An industry-standard connection for computer control of musical instruments and devices. MIPS Millions of Instructions Per Second. Refers to a computer processor's performance. MOPS Millions of Operations Per Second. In the case of DVI technology, more MOPS translate to better video quality. Intel's video processor can perform multiple video operations per instruction, thus the MOPS rating is usually greater than the MIPS rating. MPEG Motion Picture Experts Group. A working committee under the auspices of the International Standards Organization (ISO) that is attempting to define standards for the digital compression and decompression of motion video/audio for use in computer systems. The first phase of the committee's activity is addressing methods for encoding video within the 1.5 Mbit/second CD-ROM data rate. multimedia Refers to the delivery of information which combines different content formats (motion video, audio, still images, graphics, animation, text, etc.). multimedia computing Refers to the delivery of multimedia information delivered via computers. N NLM Network Loadable Module. NOS Network Operating System. NTSC National Television Systems Committee of the Electronics Industries Association (EIA) that prepared the standard of specifications approved by the Federal Communications Commission, in December 1953, for commercial color broadcasting. NTSC is still the TV standard for the U.S. and Japan, et. al - (See NTSC format). NTSC format A color television format having 525 scan lines; a field frequency of 60 Hz; a broadcast bandwidth of 4 MHz; line frequency of 15.75 KHz; frame frequency of 1/30 of a second; and a color subcarrier frequency of 3.58MHz. See also PAL, SECAM. O OEM Original Equipment Manufacturer. Company which develops, produces and sells computer and consumer hardware. P Px64 Also known as CCITT Recommendation H.261. A draft standard for motion video compression in videophone and teleconferencing applications, designed around 64 kbit/second transmission channels. DVI technology's next generation video processor will support Px64. PAL format Phase Alternation Line; the European video standard, except for France. See also NTSC, SECAM. PCM Pulse Code Modulation. The most common method of encoding an analog signal into a digital bit stream. A digitization technique, not a universally accepted standard. pixels An abbreviation for picture element. The minimum raster display element, represented as a point with a specified color or intensity level. One way to measure picture resolution is by the number of pixels used to create images. PLV Production Level Video - Highest quality DVI motion video compression algorithm today. Compression is achieved "off-line", (non-real-time), while playback (decompression) is real-time (asymmetrical compression). Independent of the technology in use, off-line compression will always produce a better image quality than real-time or symmetrical compression since more time and processing power is used per frame. R raster graphics Images defined as a set of pixels or dots in a column-and-row format. Also called bit-mapped graphics. real-time In computing, refers to an operating mode under which data is received, processed and the results returned instantaneously. resolution Number of pixels per unit of area. A display with a finer grid contains more pixels and thus has a higher resolution, capable of reproducing more detail in an image. RGB Red-Green-Blue. A type of computer color display output signal comprised of separately controllable red, green, and blue signals; as opposed to composite video, in which signals are combined prior to output. RGB monitors typically offer higher resolution than composite. See also composite video. RIFF Resource Interchange File Format. Platform-independent multimedia specification (published by Microsoft and others in 1990) that allows audio, image, animation, and other multimedia elements to be stored in a common format. See also Media Control Interface (MCI). RTV Real Time Video. On-line, symmetrical, 30 frames per second, DVI motion video compression algorithm. S sampling The first step in the process of converting an analog signal into a digital representation. This is accomplished by measuring the value of the analog signal at regular intervals called samples. These values are then encoded to provide a digital representation of the analog signal. saturated colors Strong, bright colors (particularly reds and oranges) which do not reproduce well on video; they tend to saturate the screen with color or bleed around the edges, producing a garish, unclear image. scalability The ability to vary the information content of a program by changing the amount of data that is stored, transmitted or displayed. In a video image, this translates into creating larger or smaller windows of video on screens (shrinking effect). scaling Process of uniformly changing the size of characters or graphics. SECAM format "SEquential Couleur A Memoire" (sequential color with memory), the French color TV system also adopted in Russia. The basis of operation is the sequential recording of primary colors in alternate lines. See also NTSC, PAL. SMPTE time code An 80-bit standardized edit time code adopted by SMPTE, the Society of Motion Picture and Television Engineers. See time code. Subsampling Bandwidth reduction techniques which reduce the amount of digital data used to represent an image, part of a compression process. S-video Type of video signal used in the Hi8 and S-VHS videotape formats. It transmits luminance and color portions separately, using multiple wires, thus avoiding the NTSC encoding process and its inevitable loss of picture quality. Also known as Y/C video. symmetrical compression A compression system which requires equal processing capability for compression and decompression of an image. This form of compression is used in applications where both compression and decompression will be utilized frequently. Examples include: still image databasing, still image transmission (color fax), video production, video mail, videophones, and videoconferencing. See asymmetrical compression. T teleconference A general term for a meeting not held in person. Usually refers to a multi-party telephone call, set up by the phone company or private source, which enables more than two callers to participate in a conversation. The growing use of video allows participants at remote locations to see, hear, and participate in proceedings, or share visual data ("video conference"). TIFF Tagged Image File Format. A bit map file format for describing and storing color and gray scale images. time code A frame-by-frame address code time reference recorded on the spare track of a videotape or inserted in the vertical blanking interval. It is an eight-digit number encoding time in hours, minutes, seconds, and video frames (e.g.: 02:04:48:26). tint Another name for hue. trichromatic The technical name for RGB representation of color to create all the colors in the spectrum. V VAR Value Added Reseller. A company which resells hardware and software packages to developers and/or end-users. VCR Video Cassette Recorder. An analog magnetic recording and playback machine. Generally used for recording and viewing full-motion video; also useful as a data backup device. VDRV Variable Data Rate Video. In digital systems, the ability to vary the amount of data processed per frame to match image quality and transmission bandwidth requirements. DVI symmetrical and asymmetrical systems can compress video at variable data rates. vector graphics Images defined by sets of straight lines, defined by the locations of the end points. VESA Video Electronics Standards Association. VGA Video Graphics Array. Standard IBM video display standard. Provides medium-resolution text and graphics. VGA pixel resolution is 640x480. W WAN Wide Area Network. X XGA EXtended Graphics Adapter. New IBM graphics standard that includes VGA and supports higher resolutions, up to 1024 pixels by 768 lines interlaced. Y YUV color system A color encoding-scheme for natural pictures in which the luminance and chrominance are separate. The human eye is less sensitive to color variations than to intensity variations, so YUV allows the encoding of luminance (Y) information at full bandwidth and chrominance (UV) information at half bandwidth. ActionMedia, DVI and i750 are registered trademarks of Intel Corp.