Special Feature
Home Theater Glossary
16x9-enhancement: A method of boosting resolution in 1.78:1 transfers, by horizontally, but not vertically, compressing (discarding resolution) into 4:3 proportions to fit in the standard DVD image area, and which requires horizontal expansion by ~33% or vertical contraction by ~25% to assume proper proportions for viewing. Also known as anamorphic enhancement. Because they are only compressed horizontally, 16x9-enhanced transfers contain more image resolution when used with widescreen displays than do standard 4:3 letterboxed images, which compress in both the horizontal and vertical axes. The resolution gain is 33% if the aspect ratio of the image is 1.78:1 or greater, but decreases the farther it gets away from this.
AC-3: Acronym for Audio enCoding 3, a 6-channel audio system from Dolby Laboratories. See Dolby Digital 5.1.
Anamorphic: A term used to describe intentional distortion of an image, especially by unequal scaling or magnification along perpendicular axes, such as the techniques used by the Panavision filming process to fit a widescreen image into a 1.37:1 frame and the 16x9-enhancement for DVD to fit a widescreen image into a 4:3 frame.
Anamorphic enhancement: See 16x9-enhanced.
Aspect ratio: In cinema and video, the width-to-height ratio of a film or video image. Common aspect ratios are 4:3, 1.37:1, 1.66:1, 1.78:1 (16:9), 1.85:1, and 2.35:1. For the first sixty years or so of the moving image, 4:3 or 1.37:1 was used (standard television uses the former), but in the early 1950s, "wider" aspect ratios like 1.66:1 became popular for feature films.
Avia: A DVD title containing explanations and instructions for setting up and calibrating home theater audio and video systems.
Betamax: Analog videocassette format developed by Sony in the early 1970s, and marketed from 1975 to 2002.
Cadence-based deinterlacer: A video deinterlacing system which uses digital image processing algorithms to combine interlaced video fields into progressive scan frames. With DVD, can offer superior quality to flag-based deinterlacing, since DVD flags are sometimes incorrect.
Co-ax: Short for coaxial, a type of cable where one conductor is surrounded by another in the form of a mesh. Also used to refer to a method of transmitting raw audio data from a playback device to a decoder.
Component inputs: Analog video connection system which transmits the video stream using three separate signals, one for luminance (brightness) and two for color. Superior to the other analog connection systems (RF, composite, and S-Video).
Composite video: Analog video connection system which transmits the video stream separately from the audio. An improvement over the old RF, but inferior to S-Video or component (with laserdisc, since the video is stored as composite, may be the best choice if the player's comb filter is inferior to that of the destination device).
CSS: Content Scrambling System, digital encryption system used to protect DVD-Video content.
D-VHS: A digital, high-definition videocassette format (an extension of the analog VHS) offering the capacity of approximagely four hours of HD content. Backwardly compatible with the older analog standard.
DD 2.0: See Dolby Digital 2.0.
DD 5.1: See Dolby Digital 5.1.
Digital Theater Systems: Company which develops and markets multichannel digital audio systems.
Digital TV: A television where the display screen is made up discrete picture elements (pixels) which are addressed digitally; examples are plasma, LCD, and DLP types. This term is often erroneously used to refer to analog designs capable of HDTV resolutions, such as 16x9 CRT projection sets.
Divx: Defunct home video system, a rental variant of DVD, conceived by a prominent Los Angeles entertainment law firm and developed by U.S. electronics retailer Circuit City, sold from June 1998 to June 16 of 1999.
DivX: A digital video codec popular with file downloaders and often confused with Divx, the defunct home video system.
Dolby Digital: Digital audio coding system from Dolby Laboratories, which can contain mono, stereo, or multichannel soundtracks, including Dolby Digital 1.0, Dolby Digital 2.0, or Dolby Digital 5.1.
Dolby Digital 1.0: Monophonic (single-channel) digital audio system from Dolby Laboratories.
Dolby Digital 2.0: Multichannel digital audio system from Dolby Laboratories, which can contain either Dolby Surround- or Dolby Pro Logic-type audio.
Dolby Digital 5.1: A compressed 6-channel surround sound system, developed by Dolby Laboratories and originally known as AC-3. The audio is separated into front left, center, front right, rear left, rear right, and low frequency effects (deep bass only, not full frequency, hence the ".1").
Dolby Pro Logic: A 4-channel audio system from Dolby Laboratories, with discrete front, center, and rear channels, and a shared channel for use by rear left and right.
Dolby Surround: An early multichannel audio system from Dolby Laboratories having four speakers and three channels, with the left front and right front speakers each having their own channels, and a pair of rear speakers sharing a channel.
DTS: Acronym which stands for Digital Theater Systems, a company which produces multichannel audio systems for cinema and home video, but which is generally used to refer to an lossy 6-channel audio system commonly used with laserdisc and DVD.
DVD: 5-inch optical disc format most famous and widely used for MPEG-2 video (the DVD-Video format). Also has DVD-ROM variant (computer data storage) and an audio variant. DVD discs can have one or two data layers per side, and data on one or both sides; thus, there are several different types of physical DVD media, including DVD-5 (single sided, single layer), DVD-9 (single sided, two layers), and DVD-18 (two sided, two layers).
DVD-9: A DVD disc with two data layers on one side, giving a raw storage capacity of about 7.95 gigabytes (a gigabyte is equivalent to 1024 megabytes).
DVD-18: A DVD disc with two data layers on each side, giving a raw storage capacity of about 15.9 gigabytes.
DVI: Digial Visual Interface, an interface standard for connecting both analog and digital monitors. It offers a high bandwidth for digital data transfer, and can carry digital copy protection, hence its advocacy by Hollywood studios and certain consumer electronics manufacturers.
Flag-reading deinterlacer: A DVD deinterlacing system that uses disc flags in converting interlaced video to progressive.
Front-projection: A video display based on projection that that projects its image forward onto a screen, instead of reflecting it backwards via a mirror.
FULL-mode lock: Behavior exhibited by widescreen TVs, where any signal sent to progressive inputs is displayed as 1.78:1; if the aspect ratio of the image input is anything other than 1.78:1, it is reshaped to be so. No direct user overriding of this behavior is permitted. This poses a problem for progressive-scan DVD players that output 4:3 and non-enhanced letterboxed images, because they will be improperly stretched by the display.
HDCP: High-bandwidth Digital Content Protection, a DVI-based copy protection scheme for protecting video data as it travels between the source and the display.
HDTV: High Definition Television, generally used to refer to a television system using digital transmission and having higher resolution than the old analog NTSC, PAL, and SECAM systems currently in use. In the U.S., the new HDTV system is known as ATSC, and has 18 different picture formats of varying resolutions and scan rates, with 14 being progressive-scan, and 4 interlaced.
HD-ready: A monitor or television capable of displaying high-definition signals, but not having an integral set-top box for decoding them.
Interlaced: A method of displaying video, in which the odd and even scan lines are displayed separately. This method is used by the current television standard in North America, NTSC, for legacy purposes (when it was developed in the 1930s, the available display phosphors did not allow for a quality progressive-scan image).
Joe Six-Pack: A person who is unsophisticated in matters pertaining to home theater.
Keepcase: A rectangular plastic case for storing DVD discs, having several different hub designs, including the Amaray, Alpha, and Scavano.
Laserdisc: 12-inch analog optical disc format produced from approximately 1978 to 2000, a niche format which appealed to cinemaphiles due to its higher video and audio quality, and the fact that many of the releases were oriented towards collectors (with higher video quality, OAR formatting, and extra features).
Layer change: The process whereby a DVD player reading a dual-layer disc switches from one layer to another; can result in a visible hesitation or "freezing" of playback.
Letterboxing: A technique for fitting a rectangular image into a frame with a lesser width-to-height ratio, by shrinking it until its horizontal axis fits in the destination without cropping, at the expense of leaving unused display area area (in the form of bars, usually black, at the top and bottom of the screen).
LFE: Low Frequency Effects, a low-frequency channel in audio (deep bass), such as the ".1" channel in Dolby Digital 5.1.
Macrovision: Content-protection company, which markets a form of analog content protection commonly used with pre-recorded tapes and DVDs.
MAR: Modified Aspect Ratio, the modification of a video image to something other than that envisioned by the director. Usually done to enable it to fit a television screen without letterboxing.
OAR: Original Aspect Ratio, the aspect ratio originally intended for a film, TV program, or other moving image work.
Optical connection: A digital transmission system based on light rather than electrical pulses and transmitted via fiber optics, such as Toslink. In home theater, used to transmit raw digital audio bitstreams from the playback device to the receiver.
Open matte: A presentation of a matted widescreen film (originally intended to be displayed with portions of the top and bottom of the image matted off) with the matting bars removed. Open matte presentation is a common MAR technique.
PAL: Phase Alternating Line, a television standard popular widely used outside of North America and Japan, with a 625 lines of vertical resolution at 50 frames (half-images) per second.
Pan&scan: A MAR technique in which a narrower, changing "window" into a "wider" image is maintained; as the image is being cropped, the intent is to keep the post pertitent part of it visible.
PCM: Pulse Code Modulation, an uncompressed digital audio format; used by CD-Audio, amongst others.
Pillarboxing: A technique for fitting a rectangular image into a frame with a greater width-to-height ratio, by shrinking it until its vertical axis fits in the destination without cropping, at the expense of leaving screen area unused (in the form of bars, usually black, at the sides of the screen).
Progressive scan: A video display where an entire frame is drawn in a single sweep, instead of as fields consisting of either odd or even scan lines, as with the interlaced NTSC system. This results in greatly reduced flickering and artifacting, and a more film-like image overall.
Rear-projection: Video display that projects its image backwards, using a mirror, onto a screen in the front of the set.
RSDL: Reverse Spiral Dual Layer, a DVD with dual storage layers, and which the information for the second layer starts on the innermost portion of the data area.
Set-top box: A device used to convert HDTV signals into video signals usable by the display. Often standalone, but sometimes built into sets.
Satellite speakers: Speakers used in surround-sound systems that are intended to be placed around a center channel speaker, as a part of a technique to recreate "three-dimensional" immersive sound; they tend to be smaller than the center speaker, and often contain audio to the left, right, and behind of the center channel.
Scaler: A device used to change the resolution of video images, as in upscaling, and converting non-16x9-enhanced video images for proper display on 16x9, or widescreen, sets.
S-Video: Analog video connection system where the video stream is transmitted separately, and is further broken up into chrominance (color) and luminance (brightness) signals. An improvement over RF and composite (except in certain situations with laserdisc), but inferior to component.
Super-35: A filming process which uses a 1.6:1 rather than a 1.37:1 frame (the extra horizontal area is obtained by overlaying image over the area normally occupied by audio tracks); one benefit is that it allows for 4:3 MAR video versions with less cropping than that required with anamorphic processes like Panavision.
Subwoofer: A large speaker used for low frequency effects (deep bass) in surround-sound systems.
Toslink: An optical cable standard for transmitting digital data; commonly used to transmit raw digital audio data from from playback devices to decoders.
Vertical squeeze: A technique used by some 4:3 televisions to accomodate 16x9-enhanced images without having to discard resolution, through displaying the scan lines closer together.
VHS: Analog videocassette standard developed by JVC and first marketed in the mid-1970s; for over 20 years, the dominant home video format until recently displaced by DVD.
Video processor: A device used to format and enhance video signals, especially through upconversion and scaling.
Widescreen TV: A television display having an image aspect ratio of 1.78:1; does not necessarily have a large screen.
Windowboxing: Occurs when an image is in a frame with greater dimensions, thus leaving unused display area on all four sides of the image (in the form of bars, usually black).
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