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Multimedia

Multimedia Category

Multimedia terms – also refer to sound and graphics sections

Web

  • Popular term for the World Wide Web.

Web Browser

  • A client application that fetches and displays Web pages and other WWW resources to the user. The most popular browsers are Microsoft’s Internet Explorer and Netscape’s Navigator.

Watermark

  • A background image. Typically used to decorate and identify pages in a Web site, a watermark remains stationary as the page scrolls.

VRML

  • Virtual Reality Modelling Language: a database description language applied to create 3D worlds. VRML viewers, similar to HTML Web browsers, interpret VRML data downloaded from the Web and render it on your computer. This allows the bulk of the processing to be performed locally, and drastically reduces the volume of information for transmittal from the Web.

Virtual Reality

  • Technology that allows the user to experience 3D interaction with the computer. Some VR systems may incorporate special visors, helmets, gloves, and special 3D graphics technology to simulate the real world environment.

Video1

  • The default video compression algorithm in Microsoft’s Video for Windows. Can produce 8- or 16-bit video sequences.

VideoCD

  • Format that allows the viewing of MPEG-1 (also known as the ISO IEC 11172 compression standard) video on CD-ROM. Originally devised by Philips, it allows for more than an hour of compressed video, the audio also being compressed and giving hi-fi standard. The whole point of VideoCD is cross-platform compatibility. The discs should work on suitably equipped PCs, Macs, dedicated VideoCD players, and CD-i systems. Video CD is based on the White Book standard developed by Philips and other industry leaders. Also referred to as VCD.

Video Mapping

  • A feature allowing the mapping of an AVI, MPEG movie or animation on to the surface of a 3D object.

Video Capture

  • Performed by an expansion board that digitises full-motion video from a VCR, camera or other video source. The digital video is then stored in a compressed format on hard disk.

VidCap

  • Microsoft’s Video For Windows program to capture video input to RAM or hard disk memory.

VHS

  • A VCR format introduced by JVC in 1976 to compete with Sony’s Beta format. VHS subsequently become the standard for home and industry, and Beta became obsolete. S-VHS (Super VHS) is a subsequent format that improves resolution.

VfW

  • Video for Windows: a standard established by Microsoft for the integration of digital video, animation and sound which uses the .AVI file format. The necessary software drivers are incorporated into the Windows operating system.

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.

VDI

  • Video Device Interface: a software driver interface that improves video quality by increasing playback frame rates and enhancing motion smoothness and picture sharpness. VDI was developed by Intel and will be broadly licensed to the industry.

VCR

  • Video Cassette Recorder: a videotape recording and playback machine that is available in several formats. Sony’s Beta tape was the first VCR format, but is now defunct. VHS 1/2in tape is the most commonly used format. Although VCRs are analogue recording machines, adapters allow them to store digital data for computer backup. See also VHS.

URL

  • Uniform Resource Locator: a logical address that identifies a resource on the Internet.

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).

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”).

Tearing

  • Video artefact in which portions of a video window are not updated in time for the next frame.

SVCD

  • Super VCD: an evolution of the VCD format that uses MPEG-2 compression to store between 35 and 80 minutes (depending on bit rate) of SVHS quality video on a CD. Also known as Chaoji VCD.

Subsampling

  • Bandwidth reduction techniques which reduce the amount of digital data used to represent an image. Part of a compression process.

SSE

  • Streaming SIMD Extensions: Intel’s SSE and SSE2 technologies are effectively sets of instructions for accelerating multimedia applications. SSE is found on Intel Pentium III processors; SSE2 is an incremental supported on Intel Pentium 4 processors. Some of the benefits of SSE/SSE2 include rendering higher quality images, high quality audio, MPEG2 video, simultaneous MPEG2 encoding and decoding and reduced CPU utilisation for speech recognition. See also SIMD.

sRGB

  • Standardised Red, Green and Blue: the colour space standard established by the International Electrotechnical Commission which forms the basis of colour matching hardware devices such as CRT monitors, LCD panels, projectors, printers, scanners and digital cameras and applications, including the World Wide Web.

SMPTE Timecode

  • An 80-bit standardised edit time code adopted by SMPTE, the Society of Motion Picture and Television Engineers. See also Time Code, for measuring video duration. Each frame is identified in the form hours:minutes:seconds:frames.

SIMD

  • Single Instruction Multiple Data: a method of efficiently processing data in which a single instruction is applied to multiple pieces of data simultaneously rather than to each piece of data individually. Repetitive tasks are effectively consolidated into a single one, greatly increasing the speed of data processing. Instructions of this nature are often associated with 3D graphics and multimedia. See also SSE.

SIF

  • Standard Interchange Format: format for exchanging video images of 240 lines with 352 pixels each for NTSC, and 288 lines by 352 pixels for PAL and SECAM. At the nominal field rates of 60 and 50 fields/s, the two formats have the same data rate.

SECAM

  • Sequentiel Coleur A Memoire: European video standard, used in France and Eastern Europe, with image format 4:3, 819 lines per frame, 50 Hz and 6 MHz video bandwidth with a total 8 MHz of video channel width. Like the similar PAL standard, it has a 25-frame per second update rate. The major difference from PAL is that SECAM uses FM-modulated chrominance.

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).

S-Video

  • Type of video signal used in Hi8, S-VHS and some laserdisc formats. S-Video is a hardware standard for the way a signal is carried on the cable itself and also defines the physical cable jacks. It transmits luminance and colour portions separately, using multiple wires, and avoids composite video encoding (such as NTSC) and the resulting loss of picture quality. Also known as Y-C Video.

RS170A

  • The EIA standard for the combination of signals required to form NTSC colour video.

RTV

  • Real Time Video: single step compression of video.

RPC

  • Regional Playback Control: restrictions to prevent unauthorised playback of DVD discs in countries they were not intended for.

RLE

  • Run Length Encoding: Microsoft’s video compression algorithm for base level multimedia PCs. Compresses 8-bit sequences only. Playback is also in 8 bit and isn’t scaleable for higher power PCs.

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).

RCA

  • Radio Corporation of America: refers to the standard single-ended analogue cables used to connect audio and video devices together. Typically red/white inputs are for the left/right channels of sound and yellow is for video.

QuickTime

  • Apple Computer’s video environment (like Microsoft’s Video For Windows). QuickTime video files must be converted to .AVI format to run under Microsoft’s Video For Windows.

PX64

  • Similar to MPEG, but adapted to slower bit rate. Typically used for video conferencing over an ISDN phone line.

PDF

  • Portable Document Format: Acrobat file format containing embedded fonts and graphics.

PAL

  • Phase Alternating Line: video format – used in most of Western Europe, Australia and China as well as in various African, South American and Middle Eastern countries – with a 4:3 image format, 625 lines per frame, a field frequency of 50Hz and 4 MHz video bandwidth with a total 8 MHz of video channel width. PAL has a 25-frame per second update rate and uses YUV colour space.

Overlay

  • The ability to superimpose computer graphics over a live or recorded video signal and store the resulting video image on videotape. It is often used to add titles to videotape.

NTSC

  • National Television Standards Committee: the industry group that formulated the standards for American television. An NTSC signal is a composite video signal used by televisions and VCRs in North America and some other parts of the world. The NTSC system uses 525 lines per frame, a field frequency of 60 Hz, a 30-frame per second update rate, and the YIQ colour space. Modern NTSC encoders and decoders may also use the YUV colour space.

NLE

  • Non-Linear Editing: refers to the ability to manipulate digitised video on a computer under software control. The required file segments can be cut, pasted and copied anywhere in the timeline of your project. In the context of AV applications, NLE is to video editing what the word processor was to the typewriter.

Multimedia

  • Refers to the delivery of information that combines different content formats (motion video, audio, still images, graphics, animation, text, etc.).

MPEG-4

  • A standard for video compression that is targeted at bit rates of tens of kilobytes and below to accommodate applications for digitally-encoded moving pictures and synchronised audio that can be enabled only at very low bit rates. The low bit rates targeted by MPEG-4 are the operating points for widespread communication channels, such as public switched telephone network and low-cost wired and wireless networks.

MPEG-2

  • The newer MPEG-2 standard offers resolutions of 720×480 and 1280×720 at 60 fps, with full CD-quality audio. This is sufficient for all the major TV standards, including NTSC, and even HDTV. MPEG-2 is used by DVD-ROMs and is capable of compressing a 2 hour video into a few gigabytes.

MPEG-1

  • MPEG-1 video, used in VideoCDs, is defined for non-interlaced, computer-type data streams. It is the form normally used with PCs. Typical MPEG-1 video compression ranges up to 100:1 for images comprised of 352 pixels (picture elements) by 240 lines at a refresh rate of up to 30 frames per second with 24-bit colour and CD-quality sound.

MPEG

  • Moving Picture Experts Group: a standards committee, supported by the ISO, formed to establish uniform methodologies and algorithms for digital audio and video compression.

MPC

  • Multimedia PC: a specification developed by the Multimedia Council. It defines the minimum platform capable of running multimedia software. PCs carrying the MPC logo will be able to run any software that also displays the MPC logo.

Motion-JPEG

  • A derivative of JPEG that includes some keyframe-based compression to make it suitable for video.

Motion Video

  • Video that displays real motion by displaying a sequence of images (frames) rapidly enough that the eyes see the image as a continuously moving picture.

Morph

  • Short for metamorphosing, morphing refers to an animation technique in which one image is gradually turned into another.

Mixed-Signal Device

  • Collects analogue signals and converts them into digital data to be processed. Once a DSP processes and compresses the digital data, a mixed-signal device decompresses, transmits and displays the digital data as either digital or analogue signals.

miniDVD

  • A CD-R(W) disc containing up to 15 minutes of DVD-encoded video.

MIME

  • Multi-purpose Internet Mail Extension: the format for transferring multimedia type file transfers across the Internet. Since email messages are designed for text data, this format converts non-text data into a text-based format.

MCI

  • Media Control Interface: platform-independent multimedia specification published by Microsoft Corporation and others in 1990. Provides a consistent way to control devices such as CD-ROMs and video playback units.

Laser Disc

  • An optical disk used for full-motion video. In the 1970s, various videodisc systems were introduced, but only the Philips LaserVision survived. Began being superseded by DVD-ROM during 1998.

Keyframe

  • Most video compression schemes work by taking keyframes at certain intervals and working out the differences between that frame and the following frames. This means that only small pieces of information need to be stored about each frame in order to allow the whole frame to be reconstructed. See also Delta Frame.

JavaScript

  • Netscape’s simple scripting language for Web pages which allows simple interactivity to be built into a page.

Java

  • Sun Microsystem’s object oriented programming language, designed for networked systems such as the Web.

Inverse Kinematics

  • In an object hierarchy where there are parent and child objects, grabbing one child object at the end of a chain and automatically calculating the proper movements back to the first object, all according to a series of pre-programmed constraints. An example would be an articulated hand, where moving the tip of a finger causes all the other parts to move together in a properly jointed way.

Interframe Coding

  • Compression techniques which track the differences between frames of video. Results in more compression over a range of frames than intraframe coding.

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 affect the way in which the program unfolds.

IMA

  • Interactive Multimedia Association: formed in 1991 (rooted in IVIA, Interactive Video Industry Association), an industry association chartered with creating and maintaining standard specifications for multimedia systems.

IEEE 1394 – FireWire

  • An international high-performance serial-bus standard that offers the real-time data transfer of video, audio and peripheral applications through a universal I/O interface. With this technology, digital cameras, CD-ROMs, printers, hard-disk drives and audio/stereo equipment can move data at high speeds to desktops and portable computers through a single cable.

Hyperlink

  • A pointer from text or from an image map to a page or other type of file on the WWW. On Web pages, hyperlinks are the primary way to navigate between pages and among Web sites.

HTTP

  • Hypertext Transfer Protocol: the way a Web browser and the server computer delivering Web pages communicate.

HTML

  • Hypertext Markup Language: an ASCII text-based, script-like language for creating hypertext documents like those on the Internet’s World Wide Web.

HDTV

  • High Definition TV: a television system with approximately twice the horizontal and twice the vertical resolution of current 525-line and 625-line systems, component colour coding (e.g. RGB or YCbCr) a picture aspect ratio of 16:9 and a frame rate of at least 24 Hz. The principal scanning formats have active vertical scanning lines of 720 progressive (720p), 1080 interlaced (1080i). Though 1080i as higher resolution than 720p, it doesn’t render motion quite as well the progressive scanning format.

HDCP

  • High-bandwidth Digital Content Protection: an encoding method for distributing digital content via a DVI (Digital Visual Interface) port. Using hardware on both the graphics adapter card and the monitor, HDCP encrypts data on route to a display device, where it is then decrypted.

VC-1

  • The emerging Society of Motion Picture and Television Engineers (SMPTE) standard implemented by Microsoft as Windows Media Video (WMV) 9 Advanced Profile. Formally known as SMPTE 421M, VC-1 minimises the complexity of decoding HD content through improved intermediate stage processing and more robust transforms decoding HD video twice as fast as the H.264 standard, while offering 2-to-3 times better compression than MPEG-2 and at a quality claimed to be better than MPEG-4.

H.261

  • A video compression standard developed for video teleconferencing systems. It is DCT-based and resembles MPEG to some degree. It is hoped that this will be the standard that allows a videophone from one manufacturer to “talk” to a videophone from another manufacturer, just as two different FAX machines can “talk” to each other.

GOP

  • In an MPEG signal the GOP is a group of frames between successive I frames, the others being P and/or B frames. The GOP concept allows the temporal redundancy across frames (from frame to frame) for video content to be reduced.

Full-Motion Video

  • FMV: video reproduction at 30 frames per second (NTSC-original signals), 25 frames per second (PAL-original signals) and 30 frames per second (compressed MPEG).

Frame Grabber

  • A device that “captures” and potentially stores one complete video frame. Also known as frame storer.

Frame Rate

  • How fast the source repaints the screen with a new frame. NTSC repaints the screen every 1/30th of a second for a frame rate for 30 frames per second. PAL is 25 frames per second. “Full-motion” playback of compressed MPEG files is at 30 frames per second.

Frame

  • A single, complete picture in 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 frames per second (PAL/SECAM).

FPX

  • FlashPIX: an emerging WWW standard for images. The FPX file format is a single, interoperable digital imaging format which supports other file formats like JPEG, PCX, PICT and TIFF. It has multi-resolutions because it stores images in multiple sizes.

FPS

  • Frames Per Second: an expression of frame rate.

Filtering

  • A process used in both analogue 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.

Field

  • One-half of a complete video frame, consisting of every other analogue scan line.

Digital Video – DV

  • A consumer digital video format endorsed by all major video equipment vendors. Using 1/4″ (6.35mm) metal evaporated tape, DV is recorded at 25 Mbps (18.8mm/sec) on three-hour standard cassettes or MiniDV cassettes providing up to 90 minutes of record time in long-play mode.

DeskTop Publishing – DTP

  • DTP software aids a designer to create print projects from business cards and flyers to magazines, books and posters. Many home DTP systems are affordably priced and designed to aid amateur level productions of common home printing tasks. More in-depth DTP software packages such as Quark and InDesign are highly expensive and aimed at professional print designers.

DTCP

  • Digital Transmission Content Protection: a system devised for secure transmission in the home environment over two-way transmission lines such as the FireWire bus. DTCP prevents unauthorised copying of digital content while allowing legitimate copying for purposes such as time shifting.

DSP Solution

  • The use of a Digital Signal Processor in conjunction with mixed-signal devices and embedded software to collect, process, compress, transmit and display the analogue and digital data found in today’s most popular multimedia applications.

DSS

  • Digital Satellite System, a network of satellites that broadcast digital data. An example of a DSS is DirecTV, which broadcasts digital television signals.

DirectX

  • This Microsoft Windows API was designed to provide software developers with direct access to low-level functions on PC peripherals. Before DirectX, programmers usually opted for the DOS environment, which was free of the limited multimedia feature set that characterised Windows for many years.

Digital Video

  • A video signal represented by computer-readable binary numbers that describe a finite set of colours and luminance levels.

Digitisation

  • Process of transforming analogue video signal into digital information.

Delta Frame

  • Also called Difference Frame. Contains only the pixels different from the preceding Keyframe. Delta Frames reduce the overall size of the video clip to be stored on disk. See also Keyframe.

Delivery System

  • The equipment used by end users to run or “play” an interactive program.

DeCSS

  • Open-source Linux computer code that appeared in late 1999 and allows encrypted DVD movies to be read. By reverse-engineering the Content Scrambling System (CSS) method that had been adopted by the MPAA (Motion Picture Association of America) to prevent the playing of DVD movies on unlicensed DVD players, the developers of the DeCSS utility made possible the online trading of DVD movies.

Decompression

  • To reverse the procedure conducted by the compression software algorithm to return data to its original size and condition.

DCT

  • Discrete Cosine Transform: a coding methodology – similar to Fast Fourier Transform – used, for example, in the JPEG and MPEG image compression algorithms to reduce the number of bits for actual data compression. DCT converts data into sets of frequencies, the first being the most meaningful. Latter frequencies are stripped away based on allowable resolution loss.

CSS

  • Content Scrambling System: the copy protection system used for DVD media. It is implemented in chipsets inside the DVD player.

CPPM

  • Content Copy Protection for Pre-recorded Media: the digital copy protection system used for DVD-Audio discs. Developed when the intended CSS-II method of DVD-Audio encryption was abandoned after the emergence of the DeCSS hack.

CPRM

  • Content Protection for Recordable Media: copy protection for writable DVD formats that ensures that DVD discs cannot be copied – or that first-generation copies cannot be further copied – unless permitted by the content owner.

Compression

  • The translation of data (video, audio, digital, or a combination) using a variety of computer compression algorithms and other techniques to reduce the amount of data required to accurately represent the content.

Colour Keying

  • To superimpose one image over another for special effects.

Colour Cycling

  • A means of simulating motion in a video by changing colours.

Codec

  • COmpression DECompression: any technology that converts analogue signals, such as video and voice signals, into digital form and compresses them to conserve bandwidth on a transmission path. Used by QuickTime and Video for Windows to make videos smaller for storage and to expand them for display.

CIF

  • Common Image Format: the standardisation of the structure of the samples that represent the picture information of a single frame in digital HDTV, independent of frame rate and sync/blank structure. An image that is digitised to CIF format has a resolution of 352 x 288 or 352 x 240.

Chapter

  • Subdivisions of a video title (e.g. movie) on a DVD-Video disc, each chapter being a scene or other section as defined during authoring.

CGMS

  • Copy Guard Management System: a method of preventing copies or controlling the number of sequential copies allowed. CGMS/A is added to an analogue signal (such as line 21 of NTSC). CGMS/D is added to a digital signal, such as IEEE 1394.

CGM

  • Computer Graphics Metafile: a standard format that allows for the interchanging of graphics images.

CGI

  • Common Gateway Interface: a standard method of extending Web server functionality by executing programs or scripts on a Web server in response to Web browser requests. A common use of CGI is in form processing, where the browser sends the form data to a CGI script on the server, and the script integrates the data with a database and sends back a results page as HTML.

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.

CCIR 601

  • A recommendation developed by the International Radio Consultative Committee for the digitisation of colour video signals. The CCIR 601 recommendation deals with colour space conversion from RGB to VCrCb, the digital filters used for limiting the bandwidth, the sample rate (defined as 13.5 MHz), and the horizontal resolution (720 active pixels).

CBR

  • Information that is represented in a digital form by a constant stream of bits is said to have a constant bit rate. This type of encoding has advantages for multimedia streaming applications where video will not be interrupted by sudden drops or spikes in the available bandwidth.

BLOB

  • Binary Large OBject: a database entity comprising multimedia objects – such as images, videos, and sound – stored as a collection of binary data.

AVSS

  • Audio-Video Support System: DVI system software for DOS. It plays motion video and audio.

AVI

  • Audio Video Interleaved: Microsoft’s file format for digital video and audio under Windows. Blocks of video and audio data are interspersed together in this format. It is cross-platform compatible, allowing *.AVI video files to be played under other operating systems.

AVK

  • Audio Video Kernel: DVI system software designed to play motion video and audio across hardware and operating system environments.

Avatar

  • Digital representation of yourself in a digital environment.

AV

  • Audio Visual or Audio Video: refers to equipment used in audio and video applications, such as microphones, videotape machines (VCRs), sound systems and hard disk systems for storing digitised audio or video data.

Authoring System

  • Software which helps developers design interactive courseware easily, without the painstaking detail of computer programming.

Asset

  • Term for all the constituent media files (such as text, graphics, sounds, video) that make up a multimedia movie.

APS

  • Analogue Protection System: a technology developed by Macrovision that helps thwart attempts to copy programming onto VCRs. Used on the majority of DVD-Video discs currently being produced, the technology is designed to degrade unauthorised copies made on consumer VCRs without impacting the original picture.

Applet

  • Small program that performs a limited range of tasks as part of a Web page.

Animated GIF

  • A file containing a series of GIF images that are displayed in rapid sequence by some Web browsers, giving an animated effect.

Animation Path

  • An editable line that objects follow during the course of an animation.

Anamorphic

  • Unequally scaled in vertical and horizontal dimensions. The term is used to describe the representation of a wide-screen video image by squeezing it horizontally to fit into a conventional 4:3 aspect ratio for purposes of storage and transmission.

Analogue Video

  • A video signal that represents an infinite number of smooth gradations between given video levels. Contrast with a Digital Video signal which assigns a finite set of levels.

Algorithm

  • In compression software refers to a specific formula used to compress or decompress video.

Adaptive Compression

  • Data compression software that continually analyses and compensates its algorithm, depending on the type and content of the data and the storage medium.

ActiveX

  • Microsoft’s object technology for the Web, will allow smooth animations and interactivity over the Internet.

ActiveMovie

  • Microsoft software component for handling and displaying digital video, including AVI, MPEG, and QuickTime. Incorporated into Windows 98 it is intended to replace Video for Windows. Renamed DirectShow in 1997.

Acrobat

  • Adobe’s system for producing documents to be displayed on the screen, with the correct fonts and layout.

WML

  • Wireless Markup Language: XML is a meta-language defined by the World Wide Web Consortium. This means that it is a series of rules for how to create other languages for specific applications. Content is not directly encoded in XML, but in a specific markup language defined using XML. WML is an example of a specific language for wireless applications that is fully compliant with XML’s rules. WML is thus an XML application.

WWW

  • World Wide Web: a collection of richly formatted graphic/hypermedia documents located on computers around the world and logically linked together by the Internet. With a graphical Web browser users can “surf” the Web by clicking highlighted words on the screen. Each click activates a hypertext link, connecting the user to another Web location identified by a URL.

YCrCb

  • The colour space used in the CCIR601 specification. Y is the luminance component, and the Cr and Cb components are colour difference signals. Cr and Cb are scaled versions of U and V in the YUV colour space.

YIQ

  • The colour space used in the NTSC colour system. The Y component is the black-and-white portion of the image. The I and Q parts are the colour components; these are effectively nothing more than a “watercolour wash” placed over the black and white, or luminance, component.

YUV

  • A colour encoding scheme for natural pictures in which luminance and chrominance are separate. The human eye is less sensitive to colour variations than to intensity variations. YUV allows the encoding of luminance (Y) information at full bandwidth and chrominance (UV) information at half bandwidth. YUV is used by the PAL colour system.

720p

  • One of the resolution specifications used in the HDTV. 720p stands for resolution of 1280×720 pixels and the “p” means that the video is in progressive format. Other common HDTV resolutions are 1080i and 720i.

Streaming

  • A technique for transferring data such that it can be processed as a steady and continuous stream. Streaming allows the user to play media from the Internet immediately, without having first to download the entire media file.

Dichroic Mirror

  • A mirror used to reflect light selectively according to its wavelength.

Screen Door Effect

  • Screen Door Effect (SDE) is common with LCD-based projectors and relates to a viewer’s awareness of the grid, or spacing between the pixels. The lines which form the grid are, in fact, where the panel’s control electronics are preventing light from shining through the panel.

Rainbow Effect

  • An artefact unique to single-chip DLP projectors which appears as a rainbow or multi-colour shimmer briefly noticeable by some people when they change focus from one part of the projector screen to another. It appears as a secondary image that appears at the viewer’s peripheral vision and is typically noticeable when shifting focus from a high contrast area or bright object.

Fill Factor

  • Used in connection with digital display technologies (such as LCD and DLP) to convey how much of the area of a single pixel is used for the image as opposed to the grid surrounding the pixel. The higher the “fill factor” the better. See also Screen Door Effect.

1080i

  • One of the resolution specifications used in the HDTV, 1080i stands for resolution of 1920×1080 pixels. The “i” stands for interlaced as opposed to progressive scanning, used in the other main HDTV standard, 720p.

Front Projection

  • Front projection is when a projection unit is positioned in front of the screen. See also Rear Projection.

Rear Projection

  • With rear projection, the projector is placed behind a translucent screen. See also Front Projection.

Home Theatre

  • a home theatre system is a combination of audio-video components – such as a TV, VCR, DVD player and surround-sound speaker system – designed to recreate the experience of watching a movie in a cinema.

LCOS

  • Liquid Crystal on Silicon: a liquid crystal layer on top of a pixelated, highly-reflective substrate. Below the substrate is a backplane that includes the electronics to drive the pixels. The backplane and liquid crystals are combined into a panel and packaged for use in a projection subsystem or “light engine.”

PVR

  • Personal Video Recorder: a generic term for the modern-day replacement of the VCR. Using hardware-based MPEG-2 compression like that used by DVDs, PVRs encode video data and store the data on a hard disk drive. PVRs have all of the functionality of VCRs, (recording, playback, fast forwarding, rewinding, pausing) plus the ability to instantly jump to any part of the program without having to rewind or fast forward the data stream. Also referred to a Digital Video Recorder.

ADD2

  • An ADD2 card is a PCI Express adapter card that can be used to display system output to a television, digital display, or simultaneously to a monitor and digital display.

Reed-Solomon

  • An error-correction encoding system that cycles data multiple times through a mathematical transformation in order to increase the effectiveness of the error correction, especially for burst errors (errors concentrated closely together, as from a scratch or physical defect). DVD uses rows and columns of Reed-Solomon encoding in a two-dimensional lattice, called Reed-Solomon product code (RS-PC).

Viterbi Decoder

  • A decoding algorithm developed in the late 1960s by Andrew Viterbi and used to decode a particular convolutional code (i.e. that adds redundancy to the data to improve the signal-to-noise ratio). Viterbi decoders output a 0 or a 1 based on an estimate of the input signal. Viterbi decoders are needed for reading HD DVD and Blu-ray discs.

AVC

  • Advanced Video Coding; also known as MPEG-4 AVC, MPEG-4 part 10 or H.264, this codec is expected to offer up to twice the compression of the current MPEG-4 ASP (Advanced Simple Profile) standard, as well as improvements in perceptual quality.

24p

  • Refers to 24fps progressive scan. This has been the frame rate of motion picture film since talkies arrived. It is also one of the rates allowed for transmission in the DVB and ATSC television standards, allowing them to handle film without needing any frame-rate change. It is now accepted as a part of television production formats, usually associated with high-definition, 1080-line, progressive scans.

ATSC

  • An international, non-profit organisation responsible for developing voluntary standards for digital television in the USA, including the high definition television (HDTV) and standard definition television (SDTV) families of standards. See also DVB.

DVB

  • The Digital Video Broadcasting project is a European consortia that has developed a set of standards that define digital broadcasting using existing satellite, cable, and terrestrial infrastructures. See also ATSC.

SDTV

  • Standard-definition television: a type of digital television operation method which is able to transmit and produce images which are of a higher quality than standard analogue broadcasts. SDTV is typically a 480i signal – where “480” represents the vertical resolution and “i” represents interlaced.

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