MultiMedia Glossary |
ID: Q108803
The information in this article applies to:
- Microsoft Video for Windows, versions 1.0, 1.1
SUMMARY
Below is a glossary of common terms used when describing video devices and capture routines.
MORE INFORMATION
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. ADPCM (Microsoft): Offers both real-time and non-real-time compression. When authors choose the latter option, the compression process takes longer, but they can create better-sounding audio files. Microsoft ADPCM is the codec used for Microsoft Encarta multimedia encyclopedia and other CD-based publications. 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, and so on. 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 that develops and publishes standards for voluntary use in the United States. API: Application Programming 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 that 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 that helps developers design interactive courseware easily, without the detail of computer programming. AVSS: Audio-Video Support System. DVI system software for MS-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 that 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; and 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 value associated with a pixel, representing its gray value from black to white. C Cascading: A series of components or networks, where the output of each serves as the input for the next. CAV: Constant Angular Velocity. One method of mastering or pressing video discs. With CAV, one frame of video exists on each concentric ring of the laser disc. CAV disks can freeze video, but can only hold 30 minutes of video per slide. CCIT G.711 A-Law and u-Law (Microsoft): Provided for compatibility with telephony standards for Europe and North America. This codec is supported by many hardware configurations and offers a 2-to-1 compression ratio (from 16 bits to 8 bits per sample). 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 storing 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) that provides audio, digital data, still graphics, and limited motion video. CD-ROM: Compact Disc-Read Only Memory. A 4.75-inch 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 that 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 320 x 200. 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. Chrominance: Typically refers to the color component of the video signal. Chrominance has two components: hue and saturation. Hue is defined as tint. Saturation indicates the degree to which the color is diluted by luminance (or by white light). CIE: Commission International de l'Eclairage. The international commission on illumination. Developer of color matching systems. Cinepak: Licensed from Supermac, provides good-looking video quality with good playback performance, typically 320x240 images at 15 frames per second or better. Compression times are very long, typically 12 to 16 hours for 10 minutes of finished video. Cinepak is a common video codec for CD-ROM titles for both Windows and the Macintosh. It is the codec used on Microsoft(r) Dinosaurs and Cinemania(r). CLV: Constant Linear Velocity. One method of mastering or pressing a laser disc. With CLV discs, as many video frames are fit onto each concentric ring of the disc as possible. Inner rings or tracks will hold one frame, while outer rings will hold four frames. CLV discs cannot freeze the image, but they can hold one hour of video per slide. 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: A signal that combines the luminance, chrominance, and synchronize video information onto a single line. This has been the most prevalent NTSC video format, although the recently introduced S-Video format is now available to the consumer market. Contrast: The range of light and dark values in a picture or a measure of brightness content in an image. 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 percent) 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. DSP Group, Inc. Truespeech: Offers good compression for voice-oriented sound, but is not a good option for non-voice sound. Truespeech offers a better decompression rate than GSM. Truespeech is a good option for users who want to record notes in their documents or spreadsheets, or store voice mail on their computers. Truespeech does not offer real-time compression rates, but does offer real- time decompression rates, making this codec a good alternative for use with modems and networks. 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 has been replaced by VGA. EGA pixel resolution is 640 x 350. Encoding: The process of creating a compressed file. F Field: One half of a television picture. One complete vertical scan of the picture, containing 262.5 lines. Two fields make up a complete television picture (frame). The lines of field 1 are vertically interlaced with field 2 for 525 lines of resolution. 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) or to average adjacent pixels, creating a new value from two or more pixels. Fractals: Along with raster and vector graphics, fractals are 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 screen-sized image that can be displayed in sequence with other slightly different images to create animated drawings. 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 frames per second (PAL/SECAM). Film runs at 24 frames per second. Frame Grab: The process by which individual fields of full frames of video are taken from their original analog form and stored in digital form in RAM. This RAM is usually video RAM, and, as such, the captured still-frame or field of video is displayed on the monitor or display device. Frame Grabber: A device that captures and potentially stores one complete video frame. Also known as frame storer. 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 (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 (range) of shades of black that an image has. GSM 6.10 Audio (Microsoft): Offers real-time compression (so long as the hardware is fast enough to support it), making this codec a good option for recording voice with Sound Recorder. GSM is the codec that conforms to the European Telecommunications Standards Institute - Groupe Special Mobile recommendation 6.10. GSM allows you to select from among a range of sampling rates. H HDTV: High Definition TV. A proposed standard that recommends the doubling of the current 525 lines per picture to 1050 lines and increasing the screen aspect ratio (that is, width to 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. 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 colors 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. Hue: The color tint of an image. The color of the analog video signal is determined by three factors: hue, saturation, and luminance. Hz: The abbreviation for hertz (cycles per second). I i750(r): The name of the programmable video processor family from Intel. IMA: Interactive Multimedia Association. Formed in 1991 (with help from Interactive Video Industry Association [IVIA]), an industry association chartered with creating and maintaining standard specifications for multimedia systems. IMA ADPCM: Defined by the Interactive Multimedia Association for multiple hardware platforms; similar to Microsoft ADPCM. It offers real-time compression. 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 ranging from 200 to 400 DPI. Indeo: Developed by Intel, offers good video quality and playback performance, and faster compression. Intel sells an inexpensive video capture adapter with built-in hardware compression for real-time capture and compression. 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. Interlaced: A scanning method that divides the screen into two fields, alternately drawing odd-numbered and even-numbered scan lines. Or, it is a scheme to display a video image by displaying alternate scan lines in two discrete fields. Interlaced signals are used in broadcast video and are required for video to be compliant with the National Television Standards Committee (NTSC). ISO: International Standards Organization. The worldwide group responsible for establishing and managing various standards committees and expert groups, including several image-compression standards. ISV: Independent Software Vendor. A company that develops and sells application tools and/or software titles. Interframe Coding: Compression techniques that track the differences between frames of video. This 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. This results in less compression over a range of frames than interframe coding. J JPEG: Joint Photographic Experts Group. A working committee under the guidance 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: In video, luminance is used to describe the black-and-white component of a video signal. The amount of luminance contained in a video signal is directly related to the amount of light intensity. In the absence of luminance, color video signals are black. Also, 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. The system-level specification developed by Apple Computer for addressing various media devices (videodisc/videotape players, CD players, and so forth) to its Macintosh computers. MCI: Media Control Interface. The 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. MPEG: MPEG (which stands for Motion Pictures Experts Group) is a popular codec for squeezing full-screen, VHS-quality digital video into a small data stream so that it can be played from a CD-ROM drive. It is an intense and thorough way of compressing data. It allows for VHS-quality (that is, 640x480, 30 frames-per-second) digital video playback at very low data rates. A double-speed CD-ROM would be sufficient for playback of this quality of video. Micro Channel: Personal computer bus architecture introduced by IBM in some of its PS/2 series microcomputers. Incompatible with original PC/AT (ISA) architecture. Microsoft ADPCM: Offers both real-time and non-real-time compression. When authors choose the latter option, the compression process takes longer but authors can create better-sounding audio files. Microsoft ADPCM is the codec used for Microsoft Encarta(tm) multimedia encyclopedia and other CD-based publications. Microsoft CCIT G.711 A-Law and u-Law: Provided for compatibility with telephony standards for Europe and North America. This codec is supported by many hardware configurations and offers a 2-to-1 compression ratio (from 16 bits to 8 bits per sample). Microsoft GSM 6.10 Audio: Offers real-time compression (so long as the hardware is fast enough to support it), making this codec a good option for recording voice with Sound Recorder. GSM is the codec which conforms to the European Telecommunications Standards Institute - Groupe Special Mobile recommendation 6.10. GSM allows you to select from among a range of sampling rates. Microsoft PCM converter: Included for use with Sound Blaster(tm) and other 8-bit sound cards. With this codec, 8-bit cards can play 16-bit samples. Likewise, you can use this converter to play a sample at one megahertz rate on a card that supports another rate. Microsoft Run-Length Encoding (RLE): Intended for compressing clean graphic images such as bitmaps and animating bar charts. It has a low CPU overhead, but does not handle rapid, complex scene changes well. Microsoft Video 1: Compresses data quickly, has a low CPU overhead, and is good for full motion, moderate quality video. You can also install other video and image codecs such as JPEG for image data and Motion JPEG for video data. 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. Monaural: Pertaining to a system of transmitting, recording, or reproducing sound, whereby one or more sources are channeled into a single character. 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 Pictures Experts Group (MPEG) is a popular codec for squeezing full- screen, VHS-quality digital video into a small data stream so that it can be played from a CD-ROM drive. It is an intense and thorough way of compressing data. It allows for VHS-quality (that is, 640 x 480, 30 frames- per-second) digital video playback at very low data rates. A double-speed CD-ROM would be sufficient for playback of this quality of video. Multimedia: Refers to the delivery of information that combines different content formats (motion video, audio, still images, graphics, animation, text, and so forth). Multimedia Computing: Refers to the delivery of multimedia information by computers. N NLM: Network Loadable Module. Non-Interlaced: The method of scanning all lines on a display from top to bottom in sequential order at a specific rate per second. Unlike television, which uses an interlaced scanning method, non-interlaced monitors are typically used with computers. 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. The standard established by the NTSC is referred to as the RS-170A video standard. This is a composite video signal comprised of 525 horizontal lines per frame, interlaced at a scan rate of 30 frames per second (60 fields per second). This has become the broadcast standard for the United States and Japan. 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 and SECAM. O OEM Original Equipment Manufacturer. A company that develops, produces, and sells computer and consumer hardware. P Px64 A draft standard for motion video compression in videophone and teleconferencing applications, designed for 64 Kbit/second transmission channels. DVI technology's next generation video processor will support Px64. Also known as CCITT Recommendation H.261. PAL Format: Phase Alternation Line; the European video standard, except for France. See also NTSC and 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. PCM Converter (Microsoft): Included for use with Sound Blaster and other 8-bit sound cards. With this codec, 8-bit cards can play 16-bit samples. Likewise, you can use this converter to play a sample at one megahertz rate on a card that supports another rate. 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. The highest-quality DVI motion video compression algorithm today. Compression is achieved offline (that is, non-real-time), while playback (decompression) is real-time (asymmetrical compression). Independent of the technology in use, offline compression always produces a better image quality than real-time or symmetrical compression because 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 bitmapped graphics. Real-Time: In computing, refers to an operating mode under which data is received and processed and the results are 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: The primary colors in color video--red, green and blue. RGB is often used to describe a type of video color recording scheme and the type of equipment that uses it. Also, 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 monitors. 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. Online, symmetrical, 30 frames per second, DVI motion video-compression algorithm. Run-Length Encoding (RLE) (Microsoft ): Intended for compressing clean graphic images, such as bitmaps and animating bar charts. It has a low CPU overhead but does not handle rapid, complex scene changes well. 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. Saturation: The extremes of operating range wherein the output is constant, regardless of changes in input. 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 "Sequential Couleur A Memoire": Sequential Color with Memory. This is the television standard for most of Eastern Europe. It is the French color TV system and is also adopted in Russia. Like PAL, SECAM is based on a 50Hz power system, but it uses a different encoding process and displays 819 horizontal lines per frame at a scan rate of 25 frames per second (50 fields per second). See also NTSC and PAL. SMPTE Time Code: An 80-bit standardized edit time code adopted by the Society of Motion Picture and Television Engineers (SMPTE). See Time Code. Subsampling: Bandwidth reduction techniques that reduce the amount of digital data used to represent an image (part of a compression process). S-Video: A video signal that separates the luminance and color (Y/C) components of the signal for improved quality over composite video. It is the type of video signal used in the Hi8 and S-VHS videotape formats. Because the luminance and color signals are separated, the resulting image has a much higher vertical resolution than composite video devices. S-Video equipment was originally designed for high-end television production but is now available to the consumer market. 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 that requires equal processing capability for compression and decompression of an image. This form of compression is used in applications in which both compression and decompression are used frequently. Examples include still-image databasing, still-image transmission (color fax), video production, video mail, videophones, and video conferencing. 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, that 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 conferencing). TGA: Targa Graphics Adapter. This is the format in which true color images are stored. This file format is widely accepted by the graphics industry. (It originated on the Targa board.) TIFF: Tagged Image File Format. A bitmap 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 (for example, 02:04:48:26). Tint: Another name for hue. Treble: Usually refers to the controls in an audio system that adjust the amount of high-frequency sound waves emitted by the system. Trichromatic: The technical name for RGB representation of color to create all the colors in the spectrum. Truespeech (DSP Group, Inc.): Offers good compression for voice-oriented sound, but it is not a good option for non-voice sound. Truespeech offers a better decompression rate than GSM. Truespeech is a good option for users who want to record notes in their documents or spreadsheets or store voice mail on their computers. Truespeech does not offer real-time compression rates, but does offer real- time decompression rates, making this codec a good alternative for use with modems and networks. V VAR: Value Added Reseller. A company that resells hardware and software packages to developers and/or endusers. 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. The governing body that establishes standards for the video and graphics portions of the electronics industry. VGA: Video Graphics Array. Standard IBM video display standard. Provides medium- resolution text and graphics. VGA pixel resolution is 640x480. Video 1 (Microsoft): Compresses data quickly, has a low CPU overhead, and is good for full motion, moderate quality video. You can also install other video and image codecs such as JPEG for image data and Motion JPEG for video data. Video codecs: Full-color video, which requires 3 bytes per pixel, at 640x480 resolution equals nearly 1 megabyte (MB) of digital data per frame. This means that a developer could easily use up 1 gigabyte (GB) of hard disk space by storing less than one minute of uncompressed digital video information. 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.
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Last Reviewed: April 14, 2000 |
