One of two HD formats. The resolution of the picture is 1,920 vertical pixels by 1,080 horizontal pixels and 'i' stands for interlaced scanning. Interlaced scanning is based on the principle that the screen shows every odd line at one scan of the screen and then all the even lines in a second scan.


One of the two main HD formats. 720p means that the resolution of the picture is 1,280 vertical pixels by 720 horizontal pixels. The 'p' stands for progressive scanning. Progressive scanning offers a smoother picture, as 720 horizontal lines are scanned progressively.

Aspect Ratio

The ratio of the width to height of a TV screen. The most popular are 4:3, which was the norm until the nineties, and 16:9 otherwise known as widescreen, which is more popular now and is the format used by HD.

Common Interface (CI)

The Common Interface is an extensible digital interconnect found in the digital TV market. All Common Interface equipment must comply with the EN 50221-1997 standard. The interconnect is formed between a host and a module. Examples of a host are a digital television or digital set-top box. The EN 50221 specification allows many types of module but only the Conditional Access Module (CAM) has found popularity because of the Pay TV market. The common interface shares many features of the PC Card Standard (PCMCIA). By reducing the widths of the address and data busses it has been possible to include a bi-directional parallel transport stream interface. In addition there is a command interface for communication between the host and module. This communication is in the form of a layered protocol stack which allows the host and module to share resources. For example the module can request the current date and time from the host, or can make the host display messages on the TV screen and can then read keypresses from the host remote control. The resource-sharing feature allows the CAM to request and receive PIN numbers as well as allowing the module to implement an interactive TV service. The Command Interface is extensible and there are several specification documents available which describe these extensions. For example the host could contain a modem for communication over a telephone line allowing the CAM to implement pay-per-view. However these extensions have often not proved popular with manufacturers.


DivX is a brand name of products created by DivX, Inc. (formerly DivXNetworks, Inc.), including the DivX Codec which has become popular due to its ability to compress lengthy video segments into small sizes while maintaining relatively high visual quality. The DivX codec uses lossy MPEG-4 Part 2 compression, also known as MPEG-4 ASP, where quality is balanced against file size for utility. It is one of several codecs commonly associated with "ripping", whereby audio and video multimedia are transferred to a hard disk and transcoded. Many newer "DivX Certified" DVD players are able to play DivX encoded movies, although the Qpel and global motion compensation features are often omitted to reduce processing requirements. They are also excluded from the base DivX encoding profiles for compatibility reasons.


Digital Light Processor. A device that uses millions of little mirrors - one for each pixel - to create a projected image on a screen. Most of these devices are HD.

Dolby Digital

Multi-channel digital audio surround sound format will accompany many of Sky's HD movies.


The Digital Visual Interface (DVI) is a video interface standard designed to maximize the visual quality of digital display devices such as flat panel LCD computer displays and digital projectors. It was developed by an industry consortium, the Digital Display Working Group (DDWG). It is designed for carrying uncompressed digital video data to a display. It is partially compatible with the High-Definition Multimedia Interface (HDMI) standard in digital mode (DVI-D).


Free-to-view (FTV) is a term used in the United Kingdom for certain television channels on the Sky Digital satellite platform which require a working VideoGuard receiver and viewing card to decrypt the signals, but do not require any form of continual subscription.

HD Ready

This is the all important label to look for if you are thinking about buying an HD TV. If a TV set carries the 'HD Ready' label, it will be compatible with Sky's HD broadcasts. Many new screens in the shops now sport 'HD Ready' labels.


High-bandwidth Digital Content Protection is a copyright protection system which ensures that content providers are happy to make their HD content available for viewing. HDCP is incorporated into Sky's HD box and 'HD Ready' sets in order to prevent unauthorised duplication and distribution of protected content.


The High-Definition Multimedia Interface (HDMI) is a compact audio/video connector interface for transmitting uncompressed digital streams. It represents a digital alternative to consumer analog standards such as Radio Frequency (RF) coaxial cable, composite video, S-Video, SCART, component video, D-Terminal, and VGA. HDMI connects digital audio/video sources such as set-top boxes, Blu-ray Disc players, personal computers, video game consoles, and AV receivers to compatible digital audio devices, computer monitors, and digital televisions. HDMI supports, on a single cable, any TV or PC video format including standard, enhanced, and high-definition video along with up to 8 channels of digital audio.[1] It is independent of the various digital television standards such as ATSC and DVB as these are encapsulations of compressed MPEG video streams (which can be decoded and output as uncompressed video stream on HDMI).

High Definition (HD) Television

Generally described as TV with at least four times the amount of picture data as current digital and analogue TV systems, making the picture sharper, with more intense colours and a greater sense of depth.


A Liquid Crystal Display television uses liquid crystals that act as 'shutters' within the television screen. Some LCD screens are compatible with Sky's HD broadcasts.


MPEG4 is an efficient means of compressing the data that is sent to a TV. It will be used by Sky for its HD service.


NTSC (National Television System Committee) is the analog television system used in the United States, Canada, Japan, Mexico, the Philippines, South Korea, Taiwan, and some other countries (see map). NTSC is also the name of the U.S. standardization body that adopted it.[1] The first black-and-white NTSC standard for broadcast was developed in 1941 and had no provision for color transmissions. The standard called for 525 lines of picture information in each frame, and 30 interlaced frames per second; the frame rate was later slightly adjusted for the color standard. Civilian development of commercial television was halted with the entry of the United States into the war. In 1953 a second standard was issued, which allowed color broadcasting to be compatible with the existing stock of black-and-white receivers, while maintaining the broadcast channel bandwidth already in use. This was an important commercial advantage over incompatible color systems that had also been proposed. NTSC was the first widely adopted broadcast color system. After over a half-century of use, the vast majority of over-the-air NTSC transmissions will be replaced with ATSC by February 17, 2009 in the United States, and August 31, 2011 in Canada. Various digital television systems have replaced the vacuum-tube era standard.


PAL, short for Phase Alternating Line, is a colour-encoding system used in broadcast television systems in large parts of the world. Other common analogue television systems are SECAM and NTSC. This page discusses the colour encoding system only. See Broadcast television systems and analogue television for discussion of frame rates, image resolution and audio modulation.


Picture and element condensed into one word. A pixel is a tiny sample of video information, the "little squares" that make up an overall picture. Plasma Display: A Plasma display uses hundreds of thousands of miniature, embedded cells to produce a picture. Some plasmas are compatible with HD broadcasts.


The higher the resolution, the more picture detail there is, the better the picture quality.


A situation comedy, usually referred to as a sitcom, is a genre of comedy programs which originated in radio. Today, sitcoms are found almost exclusively on television as one of its dominant narrative forms. Sitcoms usually consist of recurring characters in a common environment such as a home or workplace, and usually include laughtrack.

Sketch show

Sketch comedy consists of a series of short comedy scenes or vignettes, called "sketches," commonly between one and ten minutes long. Such sketches are performed by a group of comedic actors, either on stage or through an audio or/and visual medium such as broadcasting. Often sketches are first improvised by the actors and written down based on the outcome of these improv sessions; however, improvisation is not necessarily involved in all sketch comedy. An individual sketch or vignette is a brief scene or skit formerly used in vaudeville and used today on variety shows, comedy programs, adult entertainment, talk shows, or certain children's television programs (such as Sesame Street). Such a sketch can include footage of a "man on the street" on evening comedy television interview programs like the "Tonight Show."

Soap opera

A soap opera is an ongoing, episodic work of fiction, usually broadcast on television or radio. Programs described as soap operas have existed as an entertainment long enough for audiences to recognize them simply by the term soap. The name soap opera stems from the original dramatic serials broadcast on radio that had soap manufacturers such as Procter and Gamble, Colgate-Palmolive, and Lever Brothers as the show's sponsors. These early radio serials were broadcast in weekday daytime slots when mostly housewives would be available to listen; thus the shows were aimed at and consumed by a predominantly female audience. The term soap opera has at times been generally applied to any romantic serial, but is also used to describe the more naturalistic, unglamorous evening, prime-time drama serials of the UK such as Coronation Street.

Television series

A elevision programme, or television show is something that people watch on television. It may be a one-off broadcast or, more usually, part of a periodically recurring television series. A television series that is intended to be broadcast a finite number of episodes is usually called a miniseries or serial (although the latter term also has other meanings). North Americans call a short run lasting less than a year a season; People of the United Kingdom and the Republic of Ireland call this a series. This season or series usually consists of 6–26 installments in the USA, but in the UK there is no defined length. U.S. industry practice tends to favor longer seasons than those of some other countries.

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