HDTV Glossary of Terms
1080i means that the resolution of the picture is 1920 vertical pixels by 1080 horizontal pixels interlaced. 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.
1080p means that the resolution of the picture is 1,920 vertical pixels by 1,080 horizontal pixels and the "p" stands for progressive scanning. This format works on the same principle as 720p; the only difference is that in this type there are more pixels. Progressive scanning offers a smoother picture as horizontal lines are scanned progressively or in succession in a vertical frame that is repeated (in the USA) 30 times a second.
The aspect ratio of widescreen DTV formats used in all HDTV (High Definition TV) and some SDTV (Standard Definition TV); it stands for 16 arbitrary units of width for every 9 arbitrary units of height.
The aspect ratio of National Television Systems Committee (NTSC) TV screens; it stands for four arbitrary units of width for every three arbitrary units of height.
720p means that the resolution of the picture is 1,280 vertical pixels by 720 horizontal pixels progressive. Progressive scanning offers a smoother picture as 720 horizontal lines are scanned progressively or in succession in a vertical frame that is repeated, in the USA, 30 times a second.
Advanced Television Systems Committee (ATSC)
Advanced Television Systems Committee is responsible for establishing and developing digital television standards, as well as all 18 formats of Digital TV.
Describes a continuously variable signal of some sort. Commonly used to describe equipment or methods that do not involve the electronic digitization of a signal into data. Examples can be found in Audio Recording (Vinyl Records, Cassette tapes), Video Recording (BetacamSP, VHS), and Broadcasting (AM, FM, Conventional TV).
Artifacts are defined as unwanted visible effects in the picture caused by disturbances and errors in the video transmission or digital processing. Artifacts include “edge crawl” or “dot crawl” or “hanging dots” in analog pictures, and “pixilated”, “contouring” or “blockyness” in digital pictures.
A numerical expression of the relationship of width to height of a TV screen.
An example apsect ration is 4:3: This numerical sequence refers to the aspect ratio of the National
Television Systems Committee (NTSC) TV screen, with "4" unit width corresponding to "3" unit height, proportionally, regardless of the actual size of the screen. The 16:9 numerical sequence refers to the aspect ratio of wide screen DTV formats for all HDTV and some SDTV (Standard Definition) video. A "16" unit width corresponds to "9" unit height proportionally, regardless of the actual size of the screen. The widescreen 16:9 numerical sequence provides a viewing experience very similar to that of 35mm movies.
Bandwidth, in general, means an amount of information that can be carried in a given time period (usually a second). More exactly, it is a range of frequencies used for transmitting picture and sound information from the transmitter to your TV. Federal Communications Commission (FCC) has allocated 6 Mhz for TV broadcasters for each channel.
Bit rate is measured as "bits per second" (bps) and refers to the rate at which the data is transmitted. For Digital TV, the maximum possible bit rate within the bandwidth is 19.4 Mbps, while SDTV has a lower bit rate. The higher the bit rate, the more data is processed which usually results to higher picture resolution or better sound quality.
This term is short for "Coder-decoder." A codec is a device that converts analog video and audio signals into a digital format for transmission. It also converts received digital signals back into an analog format.
Compression refers to the reduction of the size of digital data files by
removing redundant and/or non-critical information ("data" being the elements of video, audio and other "information"). Digital TV in the U.S. would not be possible without compression.
The output of a video device (such as a DTV set top box) or the input of a DTV receiver or monitor consisting of 3 primary color signals: red, green and blue that together convey all necessary picture information. With current consumer video products, the 3 component signals have been translated in luminance (Y) and tow color difference signals (PP, PR) each on a separate wire.
An analog, encoded video signal that includes vertical and horizontal synchronizing information. Since both luminance (brightness) and chrominance (color) signals are encoded together, only a single connection wire is needed.
CRT (Cathode-Ray Tube)
CRT stands for cathode-ray tube. Invented in 1897, CRT is the most common display technology for televisions. The tube uses an electron beam to scan lines on the screen coated with phosphor, which glows when struck by the beam.
Also known as "enhanced TV." Datacasting is the act of providing enhanced options offered with some digital programming to provide additional program material or non-program related resources. This allows viewers the ability to download data (video, audio, text, graphics, maps, services, etc.) to specially equipped computers, set-top boxes, or DTV receivers.
A service provided by many cable providers, digital cable offers viewers more channels. Contrary to many consumers' beliefs, digital cable is not the same as High Definition Television or digital television; rather digital cable simply offers cable subscribers the options of paying for more services.
DTV monitors are televisions that can display a digital signal but lack an integrated tuner (unlike an integrated digital set), and thus cannot receive a digital broadcast signal without an additional set-top box.
A digital tuner serves as the decoder required to receive and display digital broadcasts. It can be included inside TV sets or via a set-top box.
Texas Instruments Inc Digital Light Processing technology, the projection and display technology which uses Digital Micromirror Devices (DMD's) to control the light output. DLP technology enables very compact, high brightness, high-resolution digital projectors.
Dolby Digital (Dolby AC-3)
This is a digital surround sound technology used in movie theaters and upscale
home theater systems that enhances audio. Home theater components with this
technology work in conjunction with a "5.1-speaker" system (five speakers plus a low-frequency sub woofer) to produce true-to-life audio that draws the listener into the onscreen action.
The process of converting high resolution video to lower resolution video. Often done to high definition camera reels so that programs can be off loaded on inexpensive standard definition editing systems before being conformed in High Definition. Also done to finished HD programs for delivery to non-HD clients.
DTV (Digital Television)
Digital TV is the umbrella term encompassing High-definition Television and several other applications, including Standard Definition Television, datacasting, multicasting and interactivity.
Digital Versatile Disk, Disk of the size of a CD, but with a storage capacity of up to 17 Gbyte. The single layer one side DVD stores up to 4.7 Gbyte, more then eight time as much as on a CD. It is an ideal media for video and multi channel audio applications. The term DVD has become synonymous with DVD-Video, which holds MPEG-2 compressed video, multi channel audio, subtitles, menus, and other features onto a DVD disk for playback in industry standard players.
EDTV (Enhanced-Definition Television)
EDTV stands for Enhanced Definition Television. The picture quality of EDTV is superior to that of standard analog TV (480i) but not as good as HDTV (1080i or 720p). EDTV displays the picture at a resolution of 852x480 (480p) lines in either 4:3 or 16:9 aspect ratios and it includes Dolby Digital sound system.
EPG stands for electronic program guide. It is a system displaying channels and program data on-screen.
Flat-panel TV typically displays picture using gas plasma or LCD technology and is only a few inches thick.
Used to describe the number of times per second that a complete picture is updated in an imaging system. In a progressive system the frame rate equals the capture rate. In an interlaced system, the frame rate is one half of the capture rate. Also see Capture Rate, Interlace Imaging, Progressive Imaging.
Front-projection TV comprises 2 parts – a separate front projector (usually placed on a table or ceiling-mounted) and a reflective screen (or simply a wall). The projector is placed at one end of the room, the screen is at the other end, and the speakers may be placed wherever they will provide you good sound experience. The picture can be rather large but remember – the larger the picture, the more visible the pixels or scan lines and the darker the image.
Ghosting means multiple overlaid TV images or “ghosts” which you can notice around the objects while watching TV. Ghosting is caused by the broadcast signal traveling to your TV through various obstacles, for example hills or tall buildings, and your antenna picks up the original TV signal along with signals reflected by the obstacles. If the ghosting is changing rather than static, it may be caused by the signal reflected by flexible objects, for example trees.
HDTV (High-Definition Television)
HDTV stands for High Definition Television. This highest-resolution subset of Digital Television offers film like picture quality with impressive surround sound. With twice the vertical and horizontal picture resolution, the picture of HDTV is approximately twice as sharp as that of NTSC. HDTV has widescreen aspect ratio of 16:9 and Dolby Digital sound system. Currently used HDTV formats - 1080i and 720p both offer reduced motion artifacts like ghosting and dot crawl.
This process divides and presents each video frame as two
fields. Imagine a video frame being divided by the odd and even horizontal lines
that make up the picture. The first field presents the odd lines; the second
field represents the even lines. The fields are aligned and timed so that, with
a still image, the human eye blends the two fields together and sees them as
one. Motion in the image makes the fields noticeable. Interlace scanning allows
only half the lines to be transmitted and presented at any given moment.
LCD (Liquid Crystal Display)
LCD stands for Liquid Crystal Displays. It refers to a flat panel technology which uses liquid crystals sandwiched between two glass plates for example in laptop computers, other small portable displays and also in televisions. Wide-screen HDTVs are available with displays of adequate resolution up to about 52 inches.
Letterbox refers to the image of a wide-screen picture on a standard 4:3 aspect
ratio television screen, typically with black bars above and below. It is used
to maintain the original aspect ratio of the original source (usually a
theatrical motion picture of 16:9 aspect ratio or wider).
The option to multicast was made possible by digital technology to allow each digital broadcast station to split its bit stream into 2, 3, 4 or more individual channels of programming and/or data services. (For example, on channel 7, you could watch 7-1, 7-2, 7-3 or 7-4.)
NTSC (National Television Systems Committee)
NTSC is the acronym that stands for National Television Systems Committee" and the name of the current analog transmission standard used in the U.S., which the committee created in 1953.
Over-the-air Broadcast (OTA)
Over-the-air Broadcast is also called Terrestrial Broadcast. It is standard over-the-air broadcast to an antenna, as opposed to satellite or cable transmission.
Picture-in-picture is a television feature in which you can see one program inside a small window on the screen, while watching another program on the large background screen. You can choose whatever you wish – you can watch two TV programs simultaneously or you can watch TV and video or DVD at the same time.
Pixel comes from the words “picture element” and it refers to the smallest element in a television picture. Pixels are single displayable video dots from which the overall picture is made up.
Plasma Displays (PDP)
Plasma display is created by thousands of tiny tubes filled by ionized gas in a plasma state. Ionized gas is very light and flat panel TVs made by this technique can be even hanged on the wall! Plasma displays offer excellent resolution and color and they are the most suitable for the home theatre.
Progressive scanning is used by some HDTVs. Progressive scanning offers rather smooth picture as 720 or 1080 horizontal lines are scanned progressively or in succession in a vertical frame that is repeated 30 times a second. Some displays, for example LCD and plasma use progressive scanning method, while CRTs may use progressive (e.g. in computer monitors) or interlaced scanning method.
Rear projection is a TV system where the picture is projected against a mirror inside the cabinet and you can watch it as you would an average television. Until recently, the rear projection TVs comprised three CRTs but the new types of rear projection TVs include LCD.
Resolution reflects the density of lines, and dots per line which make up a visual image. It is measured by the number of pixels displayed. The level of resolution directly affects picture quality. Usually the higher number of lines and dots means also sharper and more detailed picture. Analog TV has a little over 200,000 color pixels while HDTV, with 1080 vertical pixels and 1920 horizontal ones, has more than 2 million pixels creating the image.
Short for Red, Green, Blue, the colors used to create all color television and video. Often, the Red, Green and Blue components are only directly present at the image capture stage (in the camera) and on display (on the monitor). At other times they are converted to other forms such as Y, R-Y, B-Y for transportation, storage, and processing. See Y, R-Y, B-Y
SDTV (Standard-Definition Television)
SDTV stands for Standard Definition Television. The SDTV picture, having either in 4:3 or 16:9 aspect ratios, is better and of higher quality than the one of NTSC, however, it does not reach the quality and resolution of HDTV. SDTV is based on 480 lines of vertical resolution and in both interlaced and progressively scanned formats.
Set-top Box (STB)
Set-top box is responsible for receiving, converting and sending the picture and sound of the broadcast to the associated television. If your HDTV-ready TV has no built-in HDTV tuner you must connect it to a compatible HDTV STB first. Until then it will not receive and display digital television programs.
Widescreen TV is the television with 16:9 aspect ratio. 16:9 is the aspect ratio of movie screen and widescreen DTV formats used in all HDTV (High Definition TV) and some SDTV (Standard Definition TV); it stands for 16 arbitrary units of width for every 9 arbitrary units of height.