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AC-3
Dolby Laboratories AC-3 digital coding was specified by the FCC as the audio standard for DTV broadcasting, per ATSC standards. Dolby now calls AC-3 "Dolby Digital"- the same system in common use for theatrical release prints and DVD mastering. See: Dynamic Range Control and Understanding Dialnorm.
ACTV
ACTV is a US company that developed HyperTV, a technology for PC-Synchronized TV Enhancements.
Active Streaming Format (ASF)
Associated with Windows Media Files. The ASF specification defines the structure of complex, synchronized object data streams. Any object can be placed into an ASF data stream, including audio and video data objects, scripts, ActiveX controls, and HTML documents. ASF is optimized for limited-bandwidth situations.

AOLTV
AOLTV is an Internet-on-TV service provided by America Online, Inc. via cable networks and DBS providers using a proprietary set-top-box manufactured by Philips Consumer Electronics. ATVEF enhanced features may be added. Analogous to WebTVPlus. In November 2002 AOL stopped selling new AOLTV subscriptions. It continues to support existing customers.
Applet
An applet is a small application. For example, a Java interactive animation applet could be included within a web page or television enhancement if the user platform includes a Java run-time engine. Java is a more powerful language than ECMAscript (JavaScript).

Application Program Interface (API)
An Application Program Interface is a set of programming tools that pre-define functions and routines affording convenience to developers by grouping common programming material into blocks.

Asynchronous Transfer Mode (ATM)
Asynchronous Transfer Mode is a network data transfer protocol that delivers packets of a fixed size. Each ATM transfer uses a single route rather than sending packets that compose a file through various network routes, as is done in other transfer schemes. Current ATM transfer rates range from 25 to 622 megabits per second.

ATSC
The Advanced Television Systems Committee is a non-profit coalition formed to develop terrestrial digital television standards for the United States.
Attachment
In addition to the main text of an email message, files can be "attached" to a message and can contain any data including pictures, video or sound.

ATVEF
The Advanced Television Enhancement Forum is a non-profit coalition formed to promote html-based enhanced television standards and deployment. The foundation for ATVEF content is existing web standards.

Triggers to activate content may arrive via text channel 2 of line 21. The content cache can be loaded by broadcast data if available, or upon demand over the Internet. The "TV:" URL is added to reference television channels and may be used anywhere that a URL may reference an image.

Content Level 1.0 requires support for HTML 4.0, CSS 1, ECMAScript and DOM 0. (However, some receivers claiming ATVEF compliance do not support all features of HTML 4.0) (ECMAScript + DOM 0 = JavaScript 1.1) Receivers are required to provide 1MB for content caching and 1KB for session cookies. Six MIME types must be supported: text/html (HTML 4.0), text/plain, text/css (CSS1 only), image/png, image/jpg (no progressive encoding) and audio/basic.

Possible directions for future content levels include Dynamic HTML, synchronized multimedia, 3-D rendering, tuning, XML, Java, and higher-quality audio among others.

SMPTE is standardizing ATVEF as DDE.

(Related ETVCookBook pages: ATFEF Transport A - ATVEF Transport B - Localize ATVEF)
Back Channel
A two-way data connection, typically via the Internet, from the user to the network or broadcaster originating a program. Since many forms of media are distributed using a one-way distribution method, the back channel is necessary to add transactional features or to provide access to interactive content not included in a data broadcast.

Back-End
The infrastructure of servers, databases, and software that supports the actions of users who interact with delivered content.

Broadband
A class of technologies that offer high-speed Internet access to homes and businesses. DSL and Cable Modems are typical broadband technologies.

Broadcast Compositing Library (BroadcastCL)
A low level graphics API specification for interactive set top and media devices put forth by companies including Broadcom, Sun and Sony to allow multiple video, animation and text media types to be seamlessly integrated.
Broadcasting
Historically, "broadcasting" referred to the activity of radio and television stations. As cable, satellite and the Internet have developed, it is often used to describe the simultaneous real-time distribution of any media from one source to many recipients, using any transport method.

BskyB
British Sky Broadcasting is a leading provider of sports, movies, entertainment and news - whose channels are received by almost 10 million households in the United Kingdom, including 5 million digital satellite subscribers. Sky's majority owned company, Open, is developing the network's interactive services.
CableWare 2000
CableWare 2000 is a middleware product developed by WorldGate. It is designed to operate within basic set-tops such as the Scientific-Atlanta Explorer 2000 and Motorola DCT-5000.
Cache
Storage in RAM or disk set aside for temporary storage of data in order to improve access speed. A cache can be used as a store for the most recently accessed data in cases where the user often returns to recently accessed content. A cache can also be used to store new data that the system anticipates the user will be accessing soon. Usually, the oldest content of a cache is deleted without knowledge of the user in order to make room for the new content.

CANAL+
The France based Canal+ Technologies is an international provider of digital and interactive TV software solutions. The open system strategy of it's middleware product MediaHighway is consistent with the concept basis of the OpenCable Application Platform.
CDN
A Content Delivery Network (CDN) provides fee-for-service delivery of streaming content via the Internet. Their network consists of linked "edge" servers throughout the Internet that help reduce network congestion and server overload for content delivered to many users.
Centralcasting
The management of various aspects of broadcast operations, including technical, accounting, and programming support for multiple broadcast facilities from a central location.

Codec
Data compressor-decompressor software that translates data files between compressed and uncompressed states.

Compression
Any technique that reduces the size of a file or the required bandwidth for transport of a signal. Compression can be lossless, whereby the decompressed version is absolutely identical to the original. (zip is loss less). Compression can be lossey, whereby the decompressed version is not identical and is either perceptually identical or impaired. (MPEG, Real Media and MP3 are lossey compression techniques.)

Conditional Access
Conditional Access systems restrict television program access to certain groups of users either because of concerns for privacy or the desire to collect revenue for the service. Providing conditional access requires secure encryption of the program content, secure decryption in a set-top-box for each viewer, and an embedded serial number that is registered in a central conditional access system database. Cable television systems have employed a variety of conditional access systems over the years, many of which have been "broken" by pirates. The newest approach is to embed the decryption technique in a credit-card-sized "point of deployment" module (POD) that can be replaced if the system security is compromised. This approach is much more cost effective than replacing the entire set-top-box.

Cookie
A cookie is a small personalized code placed on your hard drive by a particular web site and accessed each time you visit that site so that your identity and preferences can be recognized. This is how web sites welcome you back by name, create a custom home page just for you and place subsequent orders without asking for an id each time.

CRQ
A PC-synchronous enhancement technique formerly offered by DigitalConvergence where an audio cable was connected from a television audio output jack to a PC audio input jack with appropriate free software. Triggers to activate program-related web pages on the PC were sent by inserting audible data-modulated bursts in the program audio channel using proprietary equipment. DigitalConvergence is in bankruptcy and has apparently sold the patents on this technology.

CSS
The Cascading Style Sheet recommendation from the World Wide Web Consortium (W3C) defines the derivation of web page contents from multiple sources, with a hierarchical order of precedence. This makes it possible, for example, to change just one format page in order the change the appearance of many derived content pages. CSS 1 is implemented in the current versions of the Netscape and Microsoft browsers.
DASE
The Digital Applications Software Environment is a subcommittee of the ATSC seeking to standardize and deploy technologies for enhanced television. The DASE standard provides a higher level of functionality than ATVEF and requires a more powerful enhanced TV receiver including a Java run-time engine. The DASE standard is similar in features and scope to the DVB-MHP standard. (Related ETVCookBook page: DASE)
Datacast
Delivery of program-related or non-program-related data files over a one-way broadcasting medium (like digital television). If communication is required from the viewer back to the broadcaster, an additional back channel is required.

DCT2000
(Formerly DCT-2000) A basic digital cable set-top built by General Instruments (now Motorola) that includes both cable and telephone modems. Newer models in this series include DCT2500 and DCT2600.
DCT2500
A digital cable thin client set-top by Motorola's Broadband division. This model offers all the features of their DCT2000, but adds processing power, scaled video, improved graphics and data extraction for text and other information services.
DCT2600
A digital cable thin client set-top by Motorola's Broadband division. This model offers all the features of their DCT2000, but adds processing power, scaled video, improved graphics, a hard disk for PVR use and data extraction for text and other information services.
DCT5000
(Formerly DCT-5000) An advanced digital cable thick client set-top built by General Instruments (now Motorola) that includes both cable and telephone modems. Now out of production, but new versions on this series - DCT5100 & DCT5200 are available.
DDE
Following in the footsteps of ATVEF was DDE-1, a joint effort between NIST's now defunct interactive television program and SMPTE to make the ATVEF Specification a SMPTE standard as well as clean up parts of the ATVEF specification. The basic browser functionality is now defined under SMPTE 343, "Declarative Data Essence," while transport related issues are covered in SMPTE 357M, "Declarative Data Essence, IP Multicast Encapsulation," SMPTE 364M, "Declarative Data Essence - Unidirectional Transport Protocol," and SMPTE Proposed Standard 361M, "NTSC IP and Trigger Binding to VBI."
Deployment
A deployment is the distribution of a common platform and middleware to many users, typically controlled by a cable MSO. Too often, content must be re-authored for each deployment as common standards are not yet prevalent. See Cookware:Deployments.

Dialnorm
The purpose of dialnorm (dialog normalization) is to maintain a consistent dialog level for the listener. Dolby Labratories requires dialnorm implementation in every Dolby Digital encoder and decoder.

The dialnorm metadata parameter is set in the encoder, and ranges from -31 to -1. If dialnorm is increased from -31 to -1, the decoder reduces the audio level by an equal number of decibels.

Dolby suggests setting this parameter equal to the encoder digital input average A-weighted dialog level unique to each show. They also recognize that it may be simpler to fix dialnorm at a setting appropriate to archives, and adjust the audio mix of new productions to match. This eliminates the need to implement a complex metadata system. The ETVCookbook test kitchen measures dialnorm of -25 for typical PBS network shows (with a -20 dBFS reference level.)See: Understanding Dialnorm
DirecTV
DirecTV is one of two major DBS service providers.
DirectX
DirectX is an application program interface developed by Microsoft, first for Windows 95, for creating and managing graphic images and multimedia effects in applications such as games and active Web pages. It includes the DirectDraw API for direct access to video memory.
DISH Network
The DISH Network is the DBS service of EchoStar.
DishPVR
DishPVR (formerly DISHPlayer) is a DBS receiver developed by EchoStar and WebTV that adds PVR functions including the ability to pause live shows. Earlier "DISHPlayer" models had an extra charge for the PVR functions; that functionality is now bundled into the base price.
DivX
A format promoted for the compatible interchange of compressed video files between PC's. It may become the video equivalent of MP3. It has nothing to do with DIVX, the limited-access DVD technology once promoted by Circuit City.
DOCSIS Modem
The Data Over Cable Systems Interface Specifications for cable modems were developed by Cable Labs and standardized internationally. The common term for modems meeting this specification is "Cable Labs Certified Cable Modems"
Document Object Model (DOM)
The Document Object Model is a platform and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure and style of documents. DOM 3 is the currrent working draft at W3C. DOM Level 2 HTML is currently the recommended level.

DOM Level 0 is loosely defined as "that which went before DOM 1" and has the DOM capabilities of Microsoft Internet Explorer 3.0 and Netscape Navigator 3.0 . Outside of this loose description and documentation by these two vendors, there is no standard reference.

DOM-T or transitional is a standard developed by SMPTE which is loosely defined as the intersection of the DOM capabilities of Microsoft Internet Explorer 3.0 and Netscape Navigator 3.0. It was designed to create content playable on both platforms and to be compatible with future versions of DOM.
Dolby Digital (AC-3)
Dolby Laboratories AC-3 digital coding was specified by the FCC as the audio standard for DTV broadcasting, per ATSC standards. Dolby now calls AC-3 "Dolby Digital"- the same system in common use for theatrical release prints and DVD mastering. See: Dynamic Range Control and Understanding Dialnorm.
Download
Transmission of a data file from a remote file server to a user.

DTV
The general term for digital television. Although first used to identify digital terrestrial broadcasting, it is sometimes used to describe any form of digital television including digital cable and DVD players. The Consumer Electronics Association even uses it to describe analog displays with component inputs.

DTV Multicast
The use of one digital transmitter to simultaneously send multiple programs that users can choose from.

Dublin Core Metadata Initiative
An organization convened in the mid 1990s to promote the development of standards for metadata and efficient terminology conducive to the support of such standards.
DVB
A European consortia for the standardization and deployment of digital television via terrestrial broadcast and satellite.
DVD
The Digital Versatile Disk is identical in physical size to the compact disk but capable of storing 4.7 gigabytes of data - an amount adequate for storing movie-length video encoded with MPEG-2.

DVR
Digital Video Recorder. See PVR.

DVS
Descriptive Video Service denotes an additional audio track that uses the pauses between dialogs to verbally describe the visual elements of a program. Primarily an aid for blind or low-vision users.

EchoStar
EchoStar is the operator of DBS satellies and services including the DISH Network.
ECMAScript
ECMAScript is an internationally standardized, general purpose, cross-platform programming language that can be used to provide scripting of events, objects, and actions. Prior to standardization, ECMAScript was known as Netscape JavaScript. ECMAScript + DOM 0 is equivalent to JavaScript 1.1.
EIA
The Electronic Industries Alliance is an association of consumer electronics manufacturers.
Emulator
When developing content for enhanced TV set-top boxes, it may not be possible to test the content by transmitting it to a set-top box, especially if the content developer is not local to the desired cable system or broadcaster. As an alternative, the middleware developer may provide a PC application that is intended to simulate the functionality of the middleware and related set-top box. The success of this approach depends upon the ability of the emulator author to precisely duplicate the way the actual set-top box deals with content.

Enhanced TV
The ETVCookbook considers Enhanced TV to be any new service that cannot be delivered with just a regular TV. The industry seems to be using the term "Enhanced TV" to describe interactive content that is provided for specific television programs.

Enhancement
Data sent with the intent of adding value to the user beyond what is possible with the traditional television and channel-changing remote control. Enhancement data can be sent before, during or after the broadcast. Enhancements may enhance user learning or enjoyment, may extend the life of a broadcast or may make the experience more interactive by adding on-demand resources.

Electronic Program Guide (EPG)
An electronic program guide allows the user to scan available channel offerings and tune to current programs by using their remote control to point to specific program listings. First offered in the US by DBS services, this popular feature is seen as a key advantage of digital cable and digital television receivers. Some set-top-boxes also allow programming a VCR or personal video recorder to record an upcoming show. (Related ETVCookBook pages: DTV EPG - Cable EPG)

Episode
A single show that is part of a series of shows. "The Incredible Machine" is an episode of the series "NOVA".

Explorer
The Scientific-Atlanta Explorer series of digital cable set-top boxes offer various levels of ETV functionality. (See Cookware: Platforms)
Flash
Flash is Macromedia's vector graphics-based resizable animation format with navigation and simple interactivity features. The files are small and practical for low-speed modem connections and yet provide much of the look of real-time video. Macromedia offers a free player.
Gemstar - TV Guide
Gemstar - TV Guide, Inc. holds key patents for Interactive Program Guides / Electronic Program Guides.
HAVI
Home Audio Video Interoperability is an open specification for networking digital home entertainment products. It was developed by eight of the world's leading manufacturers of audio-visual electronics.
Head-End
The facility in a cable system that aggregates the various signals that will be sent to all viewers in the cable system. The deployment of fiber which allows cable signals to travel further distances, and the increasing cost of each head-end is causing cable systems to consolidate systems and feed more consumers each head-end.

Hybrid Fiber / Coax (HFC)
HFC is a technology in rapid deployment within the cable-television industry. Fiber optic cables replace coaxial copper trunk lines from the cable head-end to individual neighborhoods of some 200-1000 homes. By doing so, the economy of home coaxial distribution is maintained, while the signal degradation of long distance coaxial runs is eliminated. This makes it possible to add new digital services on even higher RF frequencies. Moreover, with high bandwidth fiber to small groups of homes, high speed (broadband) two-way data services can be offered without congestion or interference.
HTML
Hypertext Markup Language is the standard page-description language used on the World Wide Web.
HyperTV
A technology developed by ACTV for PC-Synchronized TV Enhancements. The user installs the HyperTV application on their PC, registers a user name and password, downloads "skin" file that is the look-and feel template for a given show and logs in for the desired show in the desired time zone. Current shows include Ripley's Believe It or Not and WCW Thunder on the TBS Superstation Channel, Ultimate Fan Search on the TVLand channel, and Box Fusion on the Box Music Network.
ICAP
Interactive Communicating Application Protocol was developed by Wink for set-tops and TVs that lack the hardware resources necessary to run a full HTML browser.
IETF
The Internet Engineering Task Force (IETF) is a large open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet. It developed the "Recommended Practices", with the force or standards, that determine how the Internet infrastructure operates. It is open to any interested individual.
Indrema
Indrema was a developer of Linux-based software and hardware for TV gaming and Internet access. Indrema closed its doors in spring of 2001.

Input Device
Any piece of hardware used by a viewer to make choices or add content. The remote control, mouse, keyboard and digital camera are examples of input devices.

Interactive Network
A US company with history in interactive trials since 1988 and holder of core interactive patents. A merger with TWIN Entertainment and Two Way TV Ltd. of the UK produced the current Two Way TV (US).
Interactive TV
A term used loosely to describe Enhanced TV (interactive content provided in synchronism with specific television programs), Interactive Program Guides (IPG), Personal Video Recorders (PVR) and Walled Gardens.

iTV Production Standards Initiative
This initiative sets a goal of establishing an open XML-based iTV production standard, in order to make it more economical to produce, and to increase the quatity of iTV programming available. Version 1.1 of their standard was released in February 2003 and is available to registered participants at the website (registration is free). The standard will support the leading one- and two-screen platforms, including middleware from Liberate, OpenTV, Microsoft, and PowerTV; set-top boxes from AOLTV, UltimateTV, and MSNTV/WebTV; and PCs and Macs.
Internet Ready 7200
An OEM set-top-box built by Coollogic for branding and sale by resellers. It operated with a Coologic version of Linux and a National Semiconductor 233 MHz GX processor. It had 32MB of SDRAM and 16MB of flash memory and was to support Netscape Navigator 4.7, SSL v3 and a Java Virtual Machine. It came with a wireless keyboard and mouse, and, optionally, a variety of modems including DSL.

Internet TV
Internet TV refers to a set-top box that makes it possible to view web content on a television screen. WebTV was one of the first examples of such a device, with AOLTV a more recent example. A device labeled "Internet TV" is typically not able to respond to synchronous enhancement triggers. Since the TV screen has much lower resolution than a typical computer monitor, and since the user sits so much further away, content that is optimized for the web is often not very successful on an Internet TV. This is why some interactive set-top deployments only provide access to web pages that have been optimized for TV viewing - the "walled garden" concept.

IPG
The term Interactive Program Guide suggests an EPG with more advanced features such as program searching by genre or title and one click VCR recording.

IP Multicast
The simultaneous transmission of identical data to many users by the use of special Internet Protocol multicasting features in order to avoid clogging data networks and servers. Instead of a single server communicating with many individual computers, a single server distributes content to many distributed routers that in turn distribute to many other routers and finally to many individual users.

IPreview
IPreview is a technique developed by TiVo to allow flagging a program promo so that user can simply click to ask that the future program be recorded.
iSurfTV
iSurfTV provides a solution for the design, development, and deployment of electronic program guides (EPG). The SurfGuide technology package includes a development studio for Windows, a light client core for "low end" set-top boxes MS-TV, OpenTV, Liberate, PowerTV, etc.) and a commerce server.
Java
Java is a platform-independent high-level programming language from Sun Microsystems. It is distinct from JavaScript, a web-browser scripting language from Netscape.
JavaScript
JavaScript is an interpreted script language from Netscape for enhancing the look and functionality of web pages. It was the basis for the ECMAScript international standard. Although it bears some structural resemblance, it is distinct from Java, the high level programming language from Sun Microsystems.
JScript
JScript is Microsoft's implementation of JavaScript. The current version is claimed to be fully compliant with the ECMAScript standard.

LAeq
LAeq refers to the "equivalent" average sound level measured using the A-weighting which is most sensitive to speech intelligibility frequencies of the human ear. LAeq is prescribed in the AC-3 DTV audio standard as the proper means to set the "dialnorm" value which sets the volume of dialog in every consumer DTV receiver.

Latency
Latency is the transit time through a digital process, from input to output. It is a minimum, and usually undesirable, delay.

Liberate
Liberate provids middleware software for set-top boxes and back-end software to support set-top interactivity.
Line 21
Line 21 was chosen as a location for data to carry television closed captions as specified by EIA 608. (The top of active video begins in line 22.) The data rate was set very low, 480 bits per second, to insure that the signal could still be decoded after passing through noisy transmission channels and low-grade consumer VCRs. The primary use is for closed captions on Caption Channel 1, now legally mandated for many programs. Text Channel 2 is used for ATVEF triggers to TV enhancements, as specified in EIA 746. (Related ETVCookBook page: ATVEF Transport A)

Linear Video
Traditional television: a program that lasts a set amount of time and is intended to be viewed from beginning to end without stopping.

Local Enhancement Collaborative (LEC)
The Local Enhancement Collaborative of four public television stations developed this web resource as the primary component in its effort to further the role of local public television stations in the evolving world of enhanced television. The LEC, in partnership with PBS, explores practical ways in which stations can enhance locally produced programs, localize nationally enhanced programs and broadcast enhanced programs. The LEC efforts are made possible by a grant from the Corporation for Public Broadcasting Future Fund.
Metadata
Metadata is "data about the data". If the "data" is a video program or image (in SMPTE terminology this is the "essence"), the metadata might include information about the artist, image format, year, copyright holder, geo-spatial coordinates, compression method and any number of additional asset descriptors.

MHEG
Multimedia and Hypermedia information coding Expert Group developed this ISO standard for multimedia scripting, display and user interaction. It is suggested as an alternative to HTML and Java for enhanced television.
MHP
Multimedia Home Platform (MHP) is a standard within the DVB for enhanced television. It defines a generic interface between interactive digital applications and the terminals on which those applications execute. It supports many kinds of applications including electronic program guides, information services, synchronous enhancements, e-commerce and secure transactions. It requires a Java run-time engine within the set-top-box, allowing complex applications to be developed.
Microsoft TV (MS-TV)
Microsoft offers two levels of products for interactive services. The "Access Channel Server" provides Internet-level access for boxes including ones running their "Basic" middleware. The "TV Server" provides enhanced TV services to compatible set-tops including those running their "Advanced" middleware.
Middleware
Middleware is a layer of software that runs on top of set top box operating systems (OS) creating a consistent environment to run application software over a wide variety of set top boxes. Examples of set-top middleware include MS-TV, OpenTV, Liberate, PowerTV, etc. See: Cookware: Middleware)

MIME
Multi-Purpose Internet Mail Extensions are inserted by servers at the beginning of every Web transmission. Clients use this header to select an appropriate "player" application. Some of these players are built into the web browser, other players may be already separately installed, while others may need to be downloaded before the file can be presented. MIME is specified in several "Request for Comments" to the Internet Engineering Task Force.
Mixed Signals
Mixed Signals provided software and hardware products for the creation and encoding of synchronized television enhancements. They developed ATVEF enhancements for Wheel of Fortune and Jeapordy. Mixed Signals' product line is now handled by Ultech LLC, their enhanced programs went to Goldpocket Interactive.
MPEG
The Moving Picture Experts Group, a working group of ISO/IEC, has developed international standards for compressed digital video and audio. MPEG-1 provides resolution up to 1/4 of standard definition video, at bit rates up to roughly 1.5 Mbits/second. MPEG-2 provides a family of compression profiles and levels, including ones for High Definition Television. MPEG-4 provides an even higher range of resolution options, plus the ability to include image objects.
MPEG-1
A standard established by the Moving Picture Experts Group for compressing 525- or 625-line video and its associated audio into a 1.5 Mbit/s, 352x240 pixel stream.
MPEG-2
A group of standards established by the Moving Picture Experts Group, MPEG-2 supports several profiles for compressing video & audio. MPEG-2 profiles support DVD playback, broadcast-quality video, and HDTV.
MPEG Layer-3 Audio (MP3)
A popular audio compression standard for Internet delivery of sound files.

MSO
A Multiple System Operator is a company that owns multiple cable systems.

Association for Maximum Service TV (MSTV)
The Association for Maximum Service Television, Inc. (MSTV) is a national association of local television stations dedicated to preserving and improving the technical quality of free, universal, community-based television service to the American public.
Multicast
See IP multicast and DTV multicast.

NABTS
The North American Basic Teletext Specification as described in standard EIA 516 provides for the encoding of data within the analog vertical blanking interval at rates up to 15,600 bits/sec per video line, (with error correction). Although Teletext has enjoyed success in Europe, North America has not seen wide deployment of services, broadcast station infrastructure or the required decoder functionality in televisions. Consumer and semi-professional VTRs cannot reliably record this data.
NIST
The National Institute of Standards and Technology is building a reference DASE implementation in collaboration with the ATSC.
Norpak
Norpak is a Canadian company providing hardware and associate software for the insertion and management of data in Line 21, the analog VBI, and the Vertical Ancillary (VANC) channel within digital video.
NVOD
Near Video On Demand (NVOD) refers to a technology that makes it possible for a consumer to start watching any from a selection of popular programs within 15 minutes or so of when they make their choice. This can be accomplished over any broadcast system that has enough channel capacity to support the required multiple channels for multiple programs. Digital Cable and DBS are promoted as viable for this service. See VOD.

OCAP
OpenCable Application Platform is CableLabs middleware specification. CableLabs has selected Sun Microsystems, Liberate, and Microsoft as the primary software authors for OCAP. Going beyond the requirements of ATVEF, this specification includes key components of JavaTV.
OpenGL
OpenGL is an open specification for an applications program interface for defining 2D and 3D objects. With OpenGL, an application can create the same effects in any operating system using any OpenGL-adhering graphics adapter. Its development was initiated by Silicon Graphics.
OpenTV
A company providing middleware software for set-top boxes and back-end software to support set-top interactivity. They offer various generations of software for set-tops of varying capability. EN2 is the second generation version. OpenTV is a subsidiary of Liberty Broadband Interactive Television, Ltd.
Operating System (OS)
The layer of software in a computer-based device that directly drives the computing hardware. The operating system manages memory, input and output devices, and computing resources. Middleware requires an underlying operating system in order to run on a set-top box..

PC-Synchronous Enhancements
PC-Synchronous Enhancements are delivered over the Internet and synchronized with a related TV program. Technolgies for authoring and distributing this type of synchronous enhancement include SpiderDance and HyperTV. (Related ETVCookBook page: PC-Synchronous Enhancements)
Personal TV
A name given to the time-shifting, auto recording and preview features of the PVR.

Personal Video Recorder (PVR)
Devices that allow TV viewers to time shift, pause and fast forward (until real time) using hard-drive video storage. Systems like SONICblue's ReplayTV and TiVo also provide an electronic program guide to enable additional features tied to keywords and key programs in the TV schedule. See: Appetizers:PVR Record Triggers.
Platform
The term "platform" is used loosely within the industry to describe a particular set-top-box including it's internal operating system, a certain kind of middleware, or some combination of the two. Within the ETVCookbook, the term is used for the set-top/OS package only. See Cookware:Platforms.

POD
The Point of Deployment Module (POD) is a standardized hardware decryption security device the size of a credit card that plugs into a compatible slot in many new set-top boxes. This approach makes it possible to make set-top boxes that can operate within any cable system. The cable system simply provides the POD, and could change it for all their subscribers if the associated security system is compromised. See Conditional Access.

PopTV
A service of Liberate Technologies, Inc. for enhanced content producers. The program provides technical support, tools, and co-marketing opportunities with Liberate and Liberate partners and customers.
Post Program Enhancements
Enhancements that are transmitted during a television program they are related to, but designed to be used interactively after the broadcast concludes. Also "Post-broadcast data" (As opposed to Synchronous Enhancements and Walled Garden Enhancements.)

PowerTV
PowerTV's offerings include an operating system specifically designed and implemented for the digital interactive cable broadband network, middleware functionality supporting HTTP protocol, HTML content creation, and PersonalJava development. The PowerTV Operating System is currently deployed in over 2.5 million customer homes. PowerTV's operating system, middleware layer, and applications are most prominent in the Scientific-Atlanta networks, deployed on the Scientific-Atlanta Explorer 2000 and 3000 series, Pioneer Voyager I series set-top boxes, and PACE set-top boxes.
Progressive Download
Also referred as HTTP streaming. Allows user to view or interact with data while the content is being downloaded.

PSIP
Program and System Information Protocol is the ATSC A65 channel naming and navigation standard for digital television. (Related ETVCookBook page: DTV PSIP)
Pull
"Pull" refers to content delivered to the user upon request. Web browsing is considered "pull". See Push.

Push
"Push" refers to content delivered regardless of user interest. The user chooses what to view without controlling what is sent. Broadcast television is considered "push". See Pull.

QuickTime
A digital video file format developed by Apple. It is often used for short, small segments, and can be played on both Macintoshes and PCs. QuickTime has been named as the underlying format for the MPEG 4 standard specification.
Real Media
RealNetwork's audio/video streaming product. Their latest player, "RealOne", is available for Windows only. Older "RealPlayer" software is available for Windows, Macintosh, and several UNIX OSs. Competes with Windows Media, QuickTime, and possibly someday DivX or Ogg Theora.
ReplayTV
One of two major over-the-air PVRs (the other one is TiVo). Both of these products require a telephone line to enable value-added services such as program guides. Some cable TV set top boxes now include PVR functions.

ReplayTV is now sold by SONICblue.
RespondTV
A company which offered ATVEF-compliant tools and back-end tracking services.

Router
In a data network, the device that controls the path by which data gets from the source to the destination. The Internet is designed in a "self-healing" fashion, so that failures or congestion in a particular part of the network results in routers automatically re-routing the data through a better path.

SCTE
"The Society of Cable Telecommunications Engineers is a nonprofit professional association dedicated to advancing the careers of cable telecommunications professionals and serving the industry through excellence in providing technical training, certification and standards."
Serial Digital Interface (SDI)
SDI is the short-hand used within the video industry to describe the ITU R BT 601 standard for interface of component digital video. One component of luminance (with 720 samples per line), and two of color (each with 360 samples per line) are present, in what is called "4:2:2" sampling. There are either 10 or 8 bits per sample. The standard accommodates either "525" or "625" systems in the same 270 Mbps 75 ohm interface. There is a similar interface used for HDTV, with a data rate of 1.5 Gbps.

SDK
Software Developer's Kit. A collections of tools, utilities, and APIs to author platform specific content.

Seamless
Complex technology that is transparent to the user. (Many Internet-based interactive technologies are not considered seamless as they require a high degree of user-intervention and knowledge: installing software, connecting the modem, downloading plug-ins, etc.)

Set Top Box
Any electronic device in a box designed to sit on top of and be connected to a standard 82-channel television receiver to provide additional channels or enhanced capabilities. Nintendo, Cable boxes, and WebTV are all types of Set Top Boxes. (Related ETVCookBook page: Reference: Hardware Platforms)
Shockwave
Shockwave is a multimedia file format with features sufficient to support games. Macromedia offers a free player.
SMIL
The Synchronized Multimedia Integration Language (SMIL, pronounced "smile") enables simple authoring of interactive audiovisual presentations. SMIL is typically used for "rich media" / multimedia presentations which integrate streaming audio and video with images, text or any other media type. SMIL is an easy-to-learn HTML-like language, and many SMIL presentations are written using a simple text-editor.
Society of Motion Picture and Television Engineers (SMPTE)
The Society of Motion Picture and Television Engineers is a professional membership organization and standards setting body for the film and television industry.
SpiderDance
SpiderDance is a company providing infrastructure and tools to synchronize online content with on-air broadcasts. No special user hardware is required beyond a normal TV and PC. The user does need to actively search out the appropriate web site and time zone feed to enable the synchronous content. The technology does not allow time-shifting with either a VCR or PVR. Current programs include "webRiot" on MTV and "History IQ" for the History Channel.
SpotNet
SpotNet develops content management and delivery systems for interactive advertising on computers, PDAs, Internet Appliances, set-top-boxes, and mobile phones. It appears that they intend to centrally receive ATVEF-enhanced programs and push the related enhanced content to their "TeleWebbie" client software on various platforms. This approach avoids the need for specialized ATVEF-enabled hardware, but would seem to eliminate the possibility of placing the enhanced content surrounding or overlaid the program video. It also would preclude enjoying synchronous enhancements that have been tape delayed either at a local station or by the user.
Streaming
Streaming involves sending video from a server to a client over a network in packets. At the receiving end, the packets are reassembled to play the video as it arrives. The video file is never actually downloaded since the packets are discarded after they have been decoded and viewed.

Because the timing of packet arrival is so important, streaming servers use the Realtime Transport Protocol (RTP) instead of the HTTP protocol normally used for web content. RTP uses UDP instead of IP for transport, with no attempt to retransmit lost packets. This also allows the content to be multicast, potentially reducing server load considerably.

Some parties expand the definition of "streaming" to include media file download and refer to the above definition as "live streaming".
SVOD
Subscription Video On Demand (SVOD) is typically described as a service that has a per month fee. The trial fees range from $3.95 per month to $9.95 per month. Notable networks that have offered some form of SVOD include HBO, Showtime, and Starz/Encore.

The user accesses his/her selection through an interactive portal with full VCR functionality. Subscribers can watch any offered program as often as they wish during the subscription period without incurring any additional costs.

See VOD, NVOD.

Synchronous Enhancements
Enhancements designed to appear at specific points in time during the television program. (As opposed to Post Program Enhancements and Walled Garden Enhancements.) See also PC-Synchronous Enhancements. (Related ETVCookBook page: PC-Synchronous Enhancements)

Thick Client
The concept of robust computer processing power, storage, and memory within the end users set top box or PC client. Software application(s) can and usually reside at the users location. Also known as "Heavy" Client.

Thin Client
The concept of minimizing required storage, memory and computing horsepower at the user location by performing computing and storing information in a central location, with connections for user input and display over a medium-speed network.

TiVo
One of two major companies offering personal video recorders. (See also ReplayTV)
Transport
A transport is a unique means of media delivery. Each transport has a different combination of ownership and technical capability that determines what types of media are delivered. See Cookware:Transports.

Transport A, Transport B
Nomenclature used in the ATVEF specification to denote the means by which the enhanced content is delivered to the set-top-box. Transport A denotes delivery of the enhanced content via the Internet, either via a traditional modem or broadband connection. Transport B denotes delivery of enhanced content via a data broadcast. Even though the number of users with broadband connections to the Internet is growing, it is presumed that servers will not be able to handle the potential millions of simultaneous clicks on popular enhanced content for popular shows. Instead, by sending the content in the data-broadcast to every user cache in advance of the trigger, no excessive demands are placed upon the server. Enhanced content can use a mix of both transports; Transport A for a wide array of less popular content that would exceed the data-broadcast bandwidth and cache size, and Transport B for a smaller amount (1MB in ATVEF) of highly popular content. In either case, triggers are presumed to arrive via the broadcast. (Related ETVCookBook pages: ATVEF Transport A - ATVEF Transport B)

Trigger
A message that arrives at a specific point in time during a broadcast, intended to activate specific enhanced content. ATVEF provides triggers over text channel 2 of the closed caption channel carried on line 21 of NTSC video.
TV Crossover Link
A TV Crossover Link refers to a URL embedded within a Line 21 of television program per EIA 746. The web content might be viewed on an Internet-enabled TV or on a PC that either has a TV nearby or a TV tuner card within.

TVEveryWhere
TVEveryWhere is a product of WorldGate
TWIN Entertainment
Former name of Two Way TV (US) -- a joint venture of Interactive Network Inc. and Two Way TV of the U.K.

Please see Two Way TV.
Two Way TV
Two Way TV is a London-based full-service provider of ITV software and services and has provided enhancements for many UK programmes. Their authoring software, Ark, supports multiple platforms and provides interactivity to UK networks NTL and Telewest's digital cable as well as the BBC, Channel 4, Flextech and Sky Sports. Two Way TV also has its own branded games channel.

Two Way TV (US) is a merger of Two Way TV (UK), Interactive Network, and TWIN Entertainment. Their assets include 100+ off-the-shelf interactive games and key patents in the field.
Ultech LLC
Ultech provides products for the broadcast, post production, and media services industry. Applications addressed by the company include closed captioning, subtitling, descriptive video services, language translation, subscription audio services, and Enhanced TV.

Founded in 1991, ULTECH merged with Mixed Signals Technologies in 1999 to further the state of the art of Interactive Television. In 2002, ULTECH LLC became a wholly owned company of the National Captioning Institute Foundation.
UltimateTV
UltimateTV is the PVR offering from Microsoft WebTV Networks for DirectTV receivers. It integrates personal video recording (including dual-tuner/dual-PVR models), interactive television and Internet features.
Unicast
In the Unicast model, a server delivers content through a separate bi-directional conection with every user. The World Wide Web's HTML and TCP/IP protocals use the Unicast model, in contrast to the multicast model.

URL
The Uniform Resource Locator is the syntax used in the world wide web as a unique identifier for access to billions of individual web pages and page elements.

VANC
Within the standards established by SMPTE for digital video, there exists data corresponding to the vertical blanking interval that is unused for video. The standards allow using this Vertical Ancillary data (VANC) for any desired purpose, although industry-standard video servers and digital VTRs have only limited ability to record it. Within Standard Definition video, more than 300,000 Kb/sec can be contained in each line. With High Definition video, this amount increases to more than 900,000 Kb/sec. The VANC data is one candidate for ATVEF Transport B data.

Variable Bitrate (VBR) Encoding
Multiple pass encoding of content that varies the data compression rates based on program content.

Veon
Veon was a company that provided an end-to-end solution for authoring, deploying, managing and measuring the effectiveness of interactive programming delivered via a broadband connection to a PC equipped with a free Veon player. In 2001 Royal Philips Electronics acquired Veon and incorporated the technology in Philips MP4Net. Philips is concentrating on wireless delivery of MPEG-4 streams to PDAs.
Vertical Blanking Interval
Cathode Ray tubes, as used in nearly all televisions and computer monitors, require a small amount of time for the scanning circuitry to return to the top of the screen after completing scanning of the last line at the bottom. Video signal standards recognize this fact by inserting a number of "blank" lines at the beginning of each new picture. These blank lines make up the "vertical blanking interval."

Video Over IP
A term that describes a method of transmitting video, audio and data signals as packetized data over an IP network.

Virtual Machine
An operating environment working in conjunction with, yet independent of a host operating system. Used in such applications as a middleware component of a Set Top Box, virtual machines accommodate proprietary philosophies of associated software and service vendors. Examples include HTML virtual machines, and the Java Virtual Machine.

VOD
Video On Demand (VOD) refers to a technology that makes it possible consumers to control the start of a viewed program. For example, by remote control a consumer might pick from an on-screen list of movies and start and pause it at their convenience. If fully deployed, it would eliminate the role of video rental stores and change the nature of television services. It would require massive video servers and networks that provide individual video channels from each home to a server location. Cable Hybrid Fiber Coax (HFC) and telephone DSL are possible ways to provide this service. See NVOD.

W3C
The World Wide Web Consortium (W3C) develops interoperable technologies (specifications, guidelines, software, and tools) to lead the Web to its full potential as a forum for information, commerce, communication, and collective understanding.

Walled Garden
Content that is designed specifically to be available to some subset of users, and not generally available on the world wide web. (Related ETVCookBook page: Walled Garden)

Walled Garden Enhancements
Interactive content that is designed without links to the World Wide Web and often optimized for TV viewing with larger fonts, NTSC compliant colors, smaller pages and fewer links. (Related ETVCookBook page: Walled Garden)

WatchPoint Media
WatchPoint Media is a developer of authoring and user application software to allow tracking moving objects in a video program in order to make them "clickable". When the user enables this feature, visable shading appears over all clickable objects. The remote control cursors are then used to make the desired object active, and the press of an action key orders the product or reveals more information about it. Synchronous broadcast data, on the order of 100,000 bits/sec, is required to support this application. An advanced set-top box is also necessary.
Wavexpress
Wavexpress is a developer of e-commerce solutions for DTV. Their initial model is targeted initially at PC DTV receivers, with a migration path to DTV set top boxes. They intend to overcome limitations of traditional Internet e-commerce by deploying their "trusted client" to enable secure transactions and to protect content from piracy.
WebFlyer
WebFlyer was a multimedia set-top box produced by Eagle Wireless International and marketed by Eagle subsidiary BroadbandMagic.com under the BroadbandMagic brand name or under a customer private label. The Webflyer ran a Microsoft Windows-based operating system and was powered by a 450MHz AMD-K6(tm)-2E embedded processor, supporting broadband Internet access, wireless Bluetooth home networking, DVD movies and wireless DSL connectivity. Similar models are currently available from BroadBandMagic.
WebTV
MSN TV (formerly WebTV) is a Microsoft-owned company that provides set-top boxes and a service that allows viewing Internet content on a television screen for a monthly fee. Also the appliance with the same name. It is estimated that there have been roughly 1,000,000 WebTV boxes sold.

The WebTV Classic box provided basic "Internet On TV" functionality. The WebTV Plus boxs and MSN TV Internet Receivers also include TV enhancements. The enhancements are triggered by an EIA 746A standard URL in text channel 2 of the closed caption signal on line 21 of analog video. The enhancement content is retrieved via an analog phone line connected to a built-in modem.
WebTV For Windows
A version of the WebTV interface usable in Windows98 for users with a compatible TV tuner installed. There is no monthly fee, but it does not provide the same video-within-web-page functionality as the WebTV Plus box.

Windows Media
Microsoft's audio / video streaming product. Windows Media Player comes standard with Windows and is available for Macintosh OS. Competes with Real Media, QuickTime, and someday possibly DivX or Ogg Theora.
Wink
Wink is a company that provides end-to-end authoring, back-end and client software enhanced television solutions. Wink content is authored using ATVEF standards or Wink's ICAP, a protocol with less demands on the set-top and fewer features. Wink is now owned by Libert Broadband Interactive Television.
Wireless Markup Language (WML)
Wireless Markup Language is a language for presentation of text from Web pages on cell phones and personal digital assistants. WML is part of the Wireless Application Protocol that is being proposed as a standard.

WorldGate
WorldGate is a developer of interactive television services that enable cable subscribers to view web content, exchange email and access channel-related web sites directly (channel hyperlinking) using a suitable analog or digital cable box and remote or keyboard supplied by the cable company. Their products include CableWare 2000 middleware.
XML
Extensible Markup Language is a recommendation from the World Wide Web Consortium for a more powerful language for the description of shared data. Whereas HTML is restricted to describing the format of transmitted data, XML allows transmitting the data in a format-independent manner so that the receiving computer can exert more control over the way in which the data is processed and presented. XML can be used by any individual or group of individuals or companies that wants to share information in a consistent way.

Please suggest corrections or additional words for this glossary.

Revised Tuesday, 25-Mar-2003 15:54:39 CST - p

© 2000 - 2003 Local Enhancement Collaborative & CPB.