| High Definition Glossary |
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| Written by Marco Lecointo | |
| Friday, 25 May 2007 | |
Medias BD R BD RE BD ROM Blu-Ray Disc CD DVD Gigabyte (GB) HD DVD: High-density optical disc format designed for the storage of data and high-definition video. Layer
HDTV “tech-speak” termsAC-3 Advanced Television Systems Committee (ATSC) A/D Addressable Resolution Analog TV Artifacts Aspect Ratio ATSC ATV Bandwidth Bit Rate Channel Component (HD) Video Connection Composite Video Compression D/A DBS 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 - Six-channel digital audio standard that is part of the U.S. digital television standard; 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 (the .1). Downconvert - In DTV, the conversion from a higher-resolution input signal number to a lower one. For example, some DTV receivers can be set to downconvert an HDTV 1080i signal to a standard 480i signal that any TV can display. DTCP - Digital Transmission Copy Protection. HDTV copy-protection scheme more commonly called 5C. DTLA - Digital Transmission Licensing Administrator. The licensing organization for the 5C DTCP HDTV copy-protection technology. DTS DTV - Digital television. Generic term that refers to all digital television formats, including high-definition television (HDTV) and standard-definition television (SDTV). 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. D-VHS - Digital-VHS. Version of VHS (Video Home System) videocassette standard capable of recording HDTV via a FireWire connection; D-VHS decks are made by JVC and Mitsubishi. DVR - Digital video recorder. A television recorder such as Replay and TiVo 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; often enables smart programming, in which the device records an entire series or programming defined by keywords, genre, or personnel; and offers pause control over "live" broadcasts. Also called personal video recorder (PVR) or hard disk video recorder. EPG Frequency 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. Several formats have been proposed for these high-capacity DVD's, including Blu-ray. 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.” Interactive television: An anticipated use of television with interactive content and enhancements, enabling the viewer to interact with the program. Interactive television, in theory, would enhance the entertainment experience by providing access to additional information; combining normal TV viewing with the interactivity of a personal computer. Interlaced Scanning I/O: Input/output. Typically refers to sending information or data signals to and from devices. Often used in referring to video/audio component connections. ISDN: Integrated Services Digital Network. Enables transmission of data at high speed over the a telephone network. ISDN varies from a Basic Rate of 64 Kbits/sec up to a Primary Rate of 2 Mbps; referred to as (ISDN-30) since it comprises 30 Basic Rate channels. 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. LCD monitors typically only display video signals in a progressive scan format. LCD monitors do not use phosphors and are not susceptible to screen burn. Line Doubling 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. Lossy compression: Reducing the total data rate by discarding data that is not critical. Both video and audio for DTV transmission use lossy compression. Luminance: (Light or Brightness) In video signals the component that includes information about its brightness. Megabyte: One million bytes (actually 1,048,576); one thousand kilobytes. Modem: Modulator/demodulator. A device that transforms a typical two-level computer signal into a form suitable for transmission over a telephone line. Also does the reverse--transforms an encoded signal on a telephone line into a two-level computer signal. MPEG: Compression standards for moving images advanced by the “Motion Pictures Expert Group;” the international group of industry experts that set standards for compression of video and audio. MPEG-2 is the basis for ATSC digital television transmission. MPEG-2: Designed to cover a wide range of requirements from "VHS quality" to HDTV, using a series of algorithms and image resolution levels. MPEG-2 is the compression used by the ATSC and DVB standards. 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. The television broadcast standard in Europe and parts of Asia; (excluding France and 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 and Scan: A method used to crop the picture frame of the original source material produced in a "wide-screen" format, (any format wider than 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. Parallel cable: A multi-conductor cable carrying simultaneous transmission of digital data bits. Parallel data: Transmission of data bits, in groups, along a collection of wires (called a bus). A parallel bus may accommodate transmission of one 8-, 16-, or 32-bit byte at a time. Parallel digital: A digital video interface which uses twisted pair wiring and 25-pin D connectors to convey the bits of a digital video signal in parallel. There are various component and composite parallel digital video formats. PCM: Pulse code modulation. Sounds are reproduced by modulating the playback rate and amplitude of the sampled digital pulses. This allows PCM sound to be reproduced with varying pitch and amplitude. Pillarbox: The effect of displaying a traditional (4:3 aspect ratio) image on a widescreen (16:9) monitor. 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 Digital TV and HDTV Standards accept both Interlaced Scan and Progressive Scan broadcast and display methods. Progressive Scan has long been used in Computer Monitors. Protocol: Set of syntax rules defining exchange of data including items such as timing, format, sequencing, error checking, etc. PSIP: Program and System Information Protocol. Plasma Display — A Plasma TV Display 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. Development of Plasma Display Technology is ongoing; with specific areas of concern remaining. Plasma Displays use phosphor coated screens, placing them at high risk of screen 'burn-in'. Plasma displays are not able to reproduce the color black; various shades of gray are the best that can be achieved - this can negatively affect picture quality. The plasma pixel-cells deteriorate over time causing the picture quality to diminish (fade) 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. While a TV's Resolution can be influenced by the number of pixels in the image, it is important to note that the pixel numbers do not define ultimate resolution; ONLY the resolution of that part of the equipment. Standard Digital TV Resolutions:SDTV:
HDTV:
Return Loss: The ratio of signal power transmitted into a system, to the power reflected or returned. This is like an echo that is reflected back by impedance changes in the system. Variation in impedance from the source results in some returned signal. Cabling systems lack perfect impedance structure and matching, and have a measurable return loss. RGB: The abbreviation for red, green and blue signals, the primary colors of light (and television). Cameras and telecines have red, blue and green receptors, the TV screen has red, green and blue phosphors illuminated by red, green and blue guns. Much of the picture monitoring in a production center is in RGB. RGB is digitized with 4:4:4 sampling which occupies 50 percent more data than 4:2:2. SECAM (Système Electronique Couleur Avec Mémoire) is a signal format used in video equipment in France and the former Soviet Union. It is incompatible with PAL and NTSC formats. Set-top Box, "STB" (also: Decoder, Receiver, Tuner) Spectrum Standard Definition Television (SDTV) S-Video UHF Upconvert VHF Y/Pb/Pr - Designation for HDTV Component Type Connections Y/U/V or Y/Cr/Cb
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