AC-3

The 5.1-channel sound system specified in the Standard for Digital-HDTV. Also known as "Dolby Digital," AC-3 delivers CD-quality digital audio and provides 5 full-bandwidth channels for front left, front right, center, surround left & surround right speakers, plus an LFE (low frequency effect) subwoofer, for a total of 5.1 channels.

A/D

Analog to digital conversion (or converter). Used at transmission end of broadcast.

Artifacts

Unwanted visible effects in the picture created by disturbances in the transmission or image processing, such as 'edge crawl' or 'hanging dots' in analog pictures, or 'pixelation' in digital pictures.

Aspect Ratio

Refers to the width of a picture relative to its height. If an NTSC picture is 4 feet wide, it will be 3 feet high; thus it has a 4:3 aspect ratio. HDTV has a 16:9 aspect ratio.

ATSC  (Advanced Television Systems Committee)

The ATSC is the committee responsible for developing and establishing Digital-HDTV Standards; as well as all formats of Digital TV successors of NTSC.

Bandwidth

A range of frequencies used to transmit information such as picture and sound. A maximum bit rate possible within the bandwidth is 19.4 Mbps, which is one HDTV channel. SDTV has a lower bit rate, therefore the bandwidth can accommodate more than one channel.

Bit Rate

Measured as "bits per second," and used to express the rate at which data is transmitted or processed. The higher the bit rate, the more data that is processed and, typically, the higher the picture resolution.

Blu-ray

Optical disc storage medium. Its main uses are high-definition video & data storage.

Component  Video Connection

The output of a high definition video device (such as an HDTV set-top box), or the input of an HDTV receiver or monitor, comprised of (3) primary-color signals: red, green, and blue - each on a separate wire. The combination of these three signals convey all necessary picture information. In consumer video products, these (3) separate component signals refer to: Luminance (Y) - for Light; and two Chroma (Color) signals (Pb - blue) and (Pr - red). HDTV-Component cables and connections are commonly labeled: Y/Pb/Pr.

Compression

A method of electronically reducing the number of bits required to store or transmit data within a specified time or space. The video industry uses several types of compression methods but the method adopted for digital tv is called "MPEG2." Four full-range channels of programming and data can be compressed into the same space required by a single analog channel.

D/A

Conversion of digital to analog signals. The device is also referred to as DAC (D/A converter). In order for conventional television technology to display digitally transmitted TV data, the data must be decoded first and then converted back to an analog signal.

DLP (Digital Light Processing)

A microdisplay technology invented by Texas Instruments, DLP is based on a digital micromirror device (DMD), a chip with millions of hinged, microscopic mirrors attached, each of which corresponds to a single pixel in the projected image. Red, green, and blue light filtered through a color wheel is directed alternately onto the DMD, which switches on and off up to 5,000 times a second. The reflected light is directed through a lens and onto a screen, creating an image. High-end HDTV projectors use a three-chip solution, with separate DMD's for green, red, and blue, and forego the color wheel.

Dolby Digital

6-channel digital audio standard that, also called AC-3 or Digital 5.1. The channels consist of front left, front right, front center, surround or rear left, surround or rear right, and a separate subwoofer.

Downconvert

The conversion from a higher-resolution input signal number to a lower one.

DTS (Digital Theater Systems sound)

Discrete 5.1 channel surround system similar but not the same as Dolby Digital.

Digital Video Broadcasting (DVB)

Suite of internationally accepted open standards for digital television. DVB standards are maintained by the DVB Project, an industry consortium with more than 270 members, and they are published by a Joint Technical Committee (JTC) of European Telecommunications Standards Institute (ETSI), European Committee for Electrotechnical Standardization (CENELEC) and European Broadcasting Union (EBU).

DVI  (Digital Visual Interface)

This is a high-bandwidth video connection that carries digitized RGB picture information and can support copy-protection methods. The DVI specification allows for the presentation device and display device to agree on an optimal picture size and resolution to ensure the highest quality picture automatically.

DVR (Digital video recorder)

A digital television recorder such as you see on HDD recorders, or setop-boxes that uses a hard drive, an EPG (Electronic program guide), and internal processing to drastically simplify programmed recording and playback of recorded programs. A DVR vastly increases recording time compared to VCRs or DVD-recording decks. Also called personal video recorder (PVR) or hard disk video recorder.

EPG (Electronic program guide)

An on-screen display of channels and program data.

Frequency

The number of times per second that a signal fluctuates. The international unit for frequency is the hertz (Hz). One thousand hertz equals 1 KHz (kilohertz). One million hertz equals 1 MHz (megahertz). One billion hertz equals 1 GHz (gigahertz).

High Definition Television (HDTV)

The generally agreed upon definition of HDTV is approximately twice the vertical and horizontal picture resolution of outdated TV standards like PAL & NTSC, which essentially makes the picture twice as sharp. HDTV also has a screen ratio of 16:9 as compared with most of today's TV screens, which have a screen ratio of 4:3. HDTV offers reduced motion artifacts (i.e. ghosting, dot crawl), and offers 5.1 independent channels of CD-quality stereo surround sound, (also referred to as AC-3).

HDCP (High-bandwidth Digital Content Protection)

Copy-protection scheme developed by Intel to be used in conjunction with DVI and HDMI connections.

HDMI  (High-Definition Multimedia Interface)

USB-like digital video connectivity standard designed as a successor to DVI; can transmit both uncompressed digital audio and video signals; protected by HDCP digital copy protection.

HD-DVD (High-definition digital video disc)

Obsolete high-density optical disc format for storing data and high-definition video

IEEE 1394 (FireWire)

A digital interface developed by the IEEE 1394 working group. Transports data at 100, 200, or 400 Mbps. Can be used to connect digital television devices together. IEEE 1394 data transfer can be - “asynchronous” - or “isochronous.”
Asynchronous transport is the traditional computer memory-mapped, load and store interface. Isochronous data channels provide guaranteed data transport at a pre-determined rate. This is especially important for time-critical multimedia data where just-in-time delivery eliminates the need for costly buffering.

LCD (Liquid Crystal Display)

An LCD television or monitor uses liquid crystals that act as "shutters" within the television screen. An LCD television has thousands of small light sources at the rear of the display. A layer of cells containing the liquid crystals is placed between the light sources and the display screen. When the liquid crystal cells are electrified with current, the crystals align and block any light from shining through, or scatter allowing the light to shine through to the screen.

Letterbox Mode

A method of presenting widescreen images on a standard screen television. In order to preserve the aspect ratio of the original video content, the picture is scaled down so that it fits the available width of the television screen. Since the picture will not fill the screen vertically, dark bars are displayed above and below the picture.

MPEG-2

Standard for "the generic coding of moving pictures and associated audio information" It describes a combination of lossy video compression and lossy audio compression (audio data compression) methods which permit storage and transmission of movies using currently available storage media and transmission bandwidth.

NTSC (National television system committee)

The organization that developed the analog television standard currently in use in the U.S., Canada, and Japan. Now generally used to refer to that standard. The NTSC standard combines blue, red, and green signals modulated as an AM signal with an FM signal for audio.

PAL (Phase Alternate Line)

Tv broadcast standard in Europe & parts of Asia; (excluding France & Eastern Europe, where SECAM is the standard). PAL signals have 25 frames per second, and so are incompatible with NTSC TV. The PAL Standard transmits (625) lines of resolution, nearly (20%) more than the U.S. NTSC Standard of (525 lines).

Pan & Scan

A method used to crop the picture frame of the original source material produced in a "wide-screen" format, (any format wider than PAL/NTSC-analog's 4:3 aspect ratio) so it will fit a conventional (4:3) TV set. By "panning" the focus is kept 'centered' on the original image, in such a way as to follow the on-screen action. This can mean loss of critical detail, resulting in the scene being viewed entirely different from what the director intended.

Pillarbox

The effect of displaying a traditional (4:3 aspect ratio) image on a widescreen (16:9) tv. In order to preserve the aspect ratio of the original video content, the picture is scaled so that it fits the television screen, without distorting the image. This allows the picture to fill the height of the screen, but since the picture will not fill the screen horizontally, dark bars are displayed on both the left and right sides of the picture.

Pixel

A shortened version of "Picture cell" or "Picture element." Digital TV Pixels are rectangular-shaped, while HDTV Pixels are virtually square- shaped and significantly smaller in size. This allows High-Definition pictures to contain many more horizontal and vertical colored-dots than standard definition pictures.

Progressive Scan

In Progressive Scanning all the horizontal scan lines are scanned on to the screen at one time. The HDTV Standards accept both Interlaced Scan and Progressive Scan broadcast and display methods. Progressive Scan has long been used in Computer Monitors.

Plasma Display Panel (PDP)

A Plasma TV uses hundreds-of-thousands of miniature, embedded cells to produce a picture. Each cell equals one pixel, (picture element) and has three sub-cells. The three sub-cells are filled with a plasma gas which will 'glow' red, blue, or green (depending on the phosphor coating) when charged electrically. Light from the three "RGB" sub-cells combines to form a one colored pixel on the screen.

Resolution

A measurement of the finest (smallest) detail that is visible, or can be resolved, in a video image. TV Resolutions may be expressed as "number of pixels" in an image; or more commonly, "As Total Number of (horizontally scanned) Lines used to create the image.

High Definition TV (HDTV) Resolutions:

• 720p - 1280x720 pixels.

• 1080i - 1920x1080 pixels, interlaced.

• 1080p - 920x1080 pixels.

RGB

The abbreviation for red, green and blue signals, the primary colors of light (and television). RGB is digitized with 4:4:4 sampling which occupies 50 percent more data than 4:2:2.

SECAM (Système Electronique Couleur Avec Mémoire)

Tv standard used in video equipment in France and the former Soviet Union. It is incompatible with PAL and NTSC formats.

Set-top Box (STB)

Also called decoder, receiver, or tuner capable of receiving & decoding digital TV broadcasts.

Upconvert

The term used to describe the conversion of a lower apparent resolution to a higher number, such as "up-converting" 720p to 1080i. This is a misnomer, though, since to accomplish this, the horizontal scanning frequency is actually lowered from 45kHz to 33.75kHz. Resolution quality is not improved by this method.

Y/Pb/Pr

Designation for HDTV Component Type Connections. Advanced method for interconnecting decoded video data. Generally used where a digital TV signal source is used. Preferred connection for High Definition TV signals; enables superior quality in transmitted picture. The video signal is separated into its component parts of brightness and color differentials.

Y/U/V or Y/Cr/Cb