The following list provides brief definitions for common digital entertainment terms.
| 1394 |
The standard for a digital connection or bus used to transfer
data between two independent systems. The 1394a standard provides 400-Mbps
bandwidth but the reach is limited to 3 or 4 meters. The 1394b standard
extends the bandwidth to 800 Mbps and the reach to a whole-house environment.
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1080i |
Type of high-definition television (HDTV) image, 1,080 vertical
lines by 1,920 horizontal pixels wide, displayed in interlaced format. (16:9
aspect ratio, 29.97 Hz frame rate, as defined by the Advanced Television
Systems Committee (ATSC) standard.) |
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| 720p |
Type of high-definition television (HDTV) image, 720 vertical
lines by 1,280 horizontal pixels wide, displayed in progressive format.
(16:9 aspect ratio, 59.94 Hz, 29.97 Hz, and 23.98 Hz frame rates, as defined
by the ATSC standard.) |
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480p |
High-definition television (HDTV) image 480 vertical lines
by 720 horizontal pixels displayed in progressive format (4:3 or 16:9 aspect
ratio, 59.94 Hz, 29.97 Hz, and 23.98 Hz frame rates, as defined by the ATSC
standard.) |
|
| 480i |
Type of standard digital television (SDTV) image, 480 lines
by 720 pixels wide, displayed in interlaced format. (4:3 or 16:9 aspect
ratio, 29.97 Hz frame rate, as defined by the ATSC standard.) |
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802.11b |
IEEE specification for wireless networking at 11 Mbps. |
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| 802.11g |
IEEE specification for wireless networking at 54 Mbps over
short distances. |
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| A |
| Analog |
A type of waveform signal that contains information such
as image, voice, and data. Analog signals have unpredictable height (amplitude)
and width (frequency) and can vary infinitely over a given range. |
|
Aspect ratio |
Ratio between the width and height of the video image. Standard
National Television System Committee (NTSC), phase-alternation line (PAL),
Advanced Television Systems Committee (ATSC) (standard definition) and digital
video broadcasting (DVB) (standard definition) use a 4:3 ratio, ATSC and
DVB high-definition formats use a 16:9 format. |
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| Advanced Television Systems Committee (ATSC) |
Committee established by the FCC to define new standards
for publicly regulated broadcast television in the U.S. |
|
Advanced Television Enhancement Forum (ATVEF) |
A standard for combining intellectual property (IP) data
with television video.
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| B |
| B frame |
An MPEG-2 compressed video frame derived by extrapolation
between previous and future frames. |
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Bandwidth |
A measure of the capacity of a circuit or channel. In other
words, the amount of information transferred between points within a specified
time period. |
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| Broadband |
Term that generally refers to high-bandwith capacity. Broadband
has a multi-channel capacity that is greater or equal to 45 Mbps (US standard)
or 34 Mbps (European / international standards). |
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| C |
| Conditional access (CA) |
A cryptographic technique for controlling which receivers
are able to access a particular signal. |
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Coded orthogonal frequency division multiplexing (COFDM) |
The modulation scheme selected by the DVB committee for digital
terrestrial broadcast television. (See "Modulation" below.) |
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| Compression |
A mathematical method of reducing the amount of digital information
needed to re-create a television picture or frame. |
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Content protection (CP) |
Cryptographic and design techniques used to limit how data
flows within a receiving device and between devices. Generally this is used
to restrict copying of copyright protected material.
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| D |
| Datacasting |
Jargon referring to the propagation of information from one
source to another source |
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Demodulation |
A method for extracting digital information stored in a specific
pattern on a radio frequency (RF) signal. |
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| Digital |
Information sent as a series of high (1) and low (0) signals
separated by a fixed period of time. |
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Discrete Cosine Transform (DCT) |
A step used in the MPEG coding process to convert data from
spatial to temporal domain. |
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| Digital light projection (DLP) |
A technique developed by Texas Instruments that creates a
video image on a piece of silicon and uses mirrors and light to project
the image onto a viewable screen. |
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Digital satellite service (DSS) |
MPEG-2-based digital transmission format (e.g., DirectTV). |
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| Digital set-top-box (DSTB) |
A device that receives and decodes digital video broadcasts
for consumer viewing. |
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Digital television (DTV) |
A device that receives, decodes, and displays digital video
broadcasts (in both high-definition and standard-definition formats) for
consumer viewing |
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| Digital video broadcast (DVB) |
MPEG-2-based digital television standard that defines formats
for cable, satellite, and terrestrial broadcast. |
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Digital visual interface (DVI) |
Digital connection between a video source and a monitor.
Replaces video graphics array (VGA).
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| E |
| Encryption |
A mathematical technique for scrambling information such
that only those with a key piece of information can unscramble the information
to recreate the original message. |
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Enhanced television |
Any of several techniques for providing a viewer with additional
information associated with a television program or advertisement.
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| F |
| Federal Communications Commission (FCC) |
The U.S. government body responsible for setting and enforcing
regulations of transmissions over publicly accessible airwaves |
|
Frame |
The lines and columns of pixels that make up the displayed
image. Video speed, expressed as frames per second (FPS), gives the rate
at which the video image is updated. |
| H |
| High-definition television (HDTV) |
High-definition video formats that have 16:9 aspect ratio.
Generally refers to 1080i or 720p images. (See "1080i" and "720p"
above.) |
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Hypertext markup language (HTML) |
Standard text format used for Internet documents. |
| I |
| I frame |
An MPEG-2 compressed video frame containing most of the original
information. Used as a reference to build subsequent B and P frames. |
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Inverse discrete cosine transform (IDCT) |
A step in the MPEG decoding process to convert data from
temporal back to spatial domain. |
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| Interactive television |
A capability in DTV or DSTB that allows a user to control
the action of the television and view the results of his/her action on the
television. |
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Interlaced |
A scanning technique in a video system where odd and even
horizontal lines of a video frame are displayed during alternating update
cycles. Lines 1,3,5, etc. are displayed during the first cycle, creating
one field. Lines 2,4,6, etc. are displayed on the second cycle, creating
the next field. Two fields combine to make one frame. |
| M |
| Macrovision |
A copy-protection scheme that inhibits illegal copying of
analog television programs. Macrovision Corporation developed and licenses
the technology. |
|
Modulation |
A technique for embedding digital information in a radio
carrier wave for broadcast. |
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| Motion compensation (MC) |
A step in the MPEG-2 video decompression (decoding) process. |
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MPEG-2 |
A mathematical technique for compressing video data to reduce
the data file size. |
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| Multicasting |
Generally, multicasting refers to propagation from one source
to only a subset of potential destinations. It also means a technique for
simultaneously sending multiple DTV programs on a single channel. The frequency
used to carry a single analog television program can be used to carry up
to six digital programs. |
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| N |
| National Television System Committee (NTSC) |
The committee that decided on the compatible color television
system for the US. The FCC adopted it in 1953. |
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| P |
| Phase-alternating line (PAL) |
The analog color video composite system developed in Europe
and used by countries around the world. It is similar to the NTSC standard,
but it uses a sub-carrier phase alternation technique that makes certain
kinds of transmission errors appear to cancel. |
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P frame |
An MPEG-2 compressed video frame containing original information
and information derived from previous frames. |
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| Pixel |
The smallest unit of color in a display. Frames are made
up of lines and columns of pixels. The number of pixel lines in each frame
expresses video resolution. |
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Plasma display panel (PDP) |
Flat panel display using plasma electronic technology. |
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| Pay-per-view (PPV) |
A technique of controlling television access whereby the
customer is charged on the basis of what programs he/she watches. |
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Progressive |
A picture-scanning process where all the lines of the image
are scanned by every vertical scan. |
| Q |
| Quadrature amplitude modulation (QAM) |
A modulation method used by cable DTV that combines changes
in phase and amplitude to send four bits with each baud. |
|
Quadrature phase shift keying (QPSK) |
A modulation method used by satellite DTV that transmits
information by varying the phase of a sine wave. |
| R |
| Radio frequency (RF) |
Refers to the use of radio carrier waves to transmit a broadcast
signal. (See "Modulation" above.) |
|
Red, green, blue (RGB) |
The basic color signals used to drive a display. |
| S |
| Standard definition television (SDTV) |
Standard definition video format that has 4:3 aspect ratio.
Generally refers to 480i. (See "480i" above.) |
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| T |
| Terrestrial television |
Television signals broadcast from local radio towers. Homes
with antennas capable of picking up the broadcast signals are able to receive
the television program. |
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| U |
| Universal serial bus (USB) |
A digital connection between two separate electronic devices
which provides "plug-and-play" capability. |
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| V |
| Video on demand (VOD) |
The viewer pays a small fee to the television service provider
in order to watch particular movies listed on the on-screen television menu.
Similar to pay-per-view. |
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Vestigial sideband (VSB) |
Modulation scheme selected by the U.S. Advanced Television
Systems Committee (ATSC) for digital terrestrial broadcast television. (See
Modulation.) |
Literature
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