Glossary of A/V Terms
Glossary of A/V Terms
Reprinted with permission of the author from the book Home Theater for Everyone, © 1997–2006
by Robert Harley. www.hifibooks.com
As you read the reviews and features of The Perfect Vision, there’s a good chance you’ll
come across a term or two that you don’t understand. Not to worry. Here’s a comprehensive
compendium of the definitions of common audio and video terms to help demystify the
technospeak and clarify techy concepts.
1080i Pronounced “ten-eighty
interlaced” or “ten-eighty eye.” HDTV
format in which 1080 scanning lines
are presented in interlaced format.
3:2 pulldown A technique of
translating video material originally
shot on 24fps film to 30fps video.
Also called “inverse telecine.”
conditioner/protector, and the conditioner is plugged into the wall.
acoustic absorber Any material
that absorbs sound, such as carpet,
drapes, and thickly upholstered furniture.
acoustic diffuser Any material
that scatters sound.
3-way speaker A loudspeaker
that divides the frequency spectrum
into three parts (bass, midrange, treble) for reproduction through three or
more drivers.
5C See “Digital Transmission
Content Protection.”
5.1 channels The standard number of channels for encoding film
soundtracks. The five channels are
left, center, right, surround left, and
surround right. The “.1” channel carries frequencies below about 100Hz
and is reserved for bass effects.
acoustics The science of sound
behavior. Also refers to a room; i.e.,
“This room has good acoustics.”
AC-3 The encoding format used to
create Dolby Digital, the 5.1-channel
discrete digital surround-sound format; see “Dolby Digital.”
active subwoofer A speaker
designed to reproduce only low frequencies and that includes an integral
power amplifier to drive the speaker.
receiver or controller with six discrete
inputs that will accept the six discrete
outputs from a Dolby Digital or DTS
decoder. This feature allows you to
add discrete digital decoding to a
receiver or controller.
adjacent-channel selectivity
720p HDTV format in which the
set the terrestrial transmission and
format standards for digital television.
Also, the transmitted signals that follow that format.
image is composed of 720 scanning
lines presented in progressive format.
A/B comparison A back-andforth listening comparison between
two audio or video presentations, A
and B.
AC line-conditioner/protector
A device that filters noise from the AC
powerline and isolates equipment
from voltage spikes and surges.
Some AC line-conditioners/protectors
also protect equipment from lightning
strikes. Home-theater equipment is
plugged into the AC line-
analog-to-digital converter
(A/D, ADC) A circuit that converts
an analog signal to a digital signal.
anamorphic A film or video format in
which a widescreen image has been
“squeezed” horizontally (either with
lenses or by digital manipulation) to
fit a standard 4:3 aspect ratio. Correct
picture geometry is restored on playback by “unsqueezing” the image into
its original aspect ratio. The anamorphic format delivers the correct aspect
ratio without sacrificing resolution.
Anamorphic DVDs may carry the legend “Anamorphic Widescreen,” “16:9
Enhanced” or “Enhanced for
Widescreen Televisions.”
AV/C Audio-Video Control, a simple
FireWire-based technology for controlling the components in a home-theater system as a single unit with one
remote control.
A/V input An input on an A/V
receiver or controller that includes
both audio and video jacks.
A/V loop An A/V input and A/V output pair found on all A/V receivers
and controllers. Used to connect a
component that records as well as
plays back audio and video signals.
A DVD recorder is connected to a
receiver’s or controller’s A/V loop.
A/V preamplifier Also called by
its more descriptive name of an “A/V
controller,” the A/V preamplifier is a
component that performs surround
decoding and lets you control the playback volume and select which source
you want to watch and listen to.
ADC See “analog-to-digital converter.”
5.1-channel ready An A/V
analog An analog signal is one in
which the varying voltage is an analog of the acoustical waveform; i.e., it
is continuously variable. Contrasted
with a digital signal, in which binary
ones and zeros represent audio or
video information.
Tuner specification that describes a
tuner’s ability to reject radio stations
adjacent to the desired station.
Advanced Television System
Committee (ATSC) Group that
ANSI lumens Measurement of a
video display’s light output, or the
light output from a front projector as
reflected from a projection screen.
A/V preamplifier/tuner An A/V
aspect ratio The width-to-height
ratio of a visual image. Standard television sets have an aspect ratio of
4:3 (1.33:1). Widescreen television
sets have an aspect ratio of 16:9
(1.78:1).
A/V receiver The central compo-
aspect-ratio control A feature
preamplifier that includes, in the same
chassis, an AM and/or FM tuner for
receiving radio broadcasts.
nent of a home-theater system; receives
signals from source components, selects
which signal you watch and listen to,
controls the playback volume, performs
surround decoding, receives radio
broadcasts, and amplifies signals to
drive a home-theater loudspeaker system. Also called a “surround receiver.”
Tuner specification describing a tuner’s
ability to reject stations two channels
away from the desired station.
in some HD-ready televisions that
allows you to manually adjust the
aspect ratio.
baffle The front surface of a loud-
atmosphere See “ambience.”
speaker, on which the drivers are
mounted.
ambience Spatial aspects of a film
ATSC See “Advanced Television
soundtrack that create a sense of size
and atmosphere, usually reproduced
by the surround speakers.
System Committee.”
alternate-channel selectivity
ampere Unit of electrical current,
abbreviated A.
A/V Short for audio/video. Identifies
a component or system as one that
processes video as well as audio
signals.
AVGuide.com Reprinted from Home Theater for Everyone by Robert Harley
balanced cable A cable that carries a balanced signal on three conductors. Contrast with unbalanced (or
“single-ended”) cable.
balanced output A connector on
some A/V products that presents the
Glossary of A/V Terms (continued)
audio signal on three conductors,
rather than the two conductors of an
unbalanced output. Balanced outputs
appear on XLR jacks. Found only on
high-end products.
Usually reserved for sets with diagonal
dimensions greater than 40 inches.
binding post A connection on
receivers and power amplifier for
attaching loudspeaker cables.
banana jack A small tubular connector found on A/V receivers and
power amplifiers for connecting
speaker cables terminated with
banana plugs.
bipolar speaker A speaker that
produces sound equally from the front
and the back. Unlike the dipolar speaker, the bipolar’s front and rear sound
waves are in phase with each other.
banana plug A common speakercable termination that fits into a
banana jack.
bandwidth In audio, the range of
frequencies that a device can process
or pass; the human ear has a bandwidth of 20Hz–20kHz. In radio and
television transmission, the range of
frequencies occupied by one channel
of information; a television broadcast
channel occupies a band of frequencies 6MHz wide. In digital, the maximum bit rate a system is capable of
conveying; the bandwidth of a
FireWire 400 connection is 400Mbps.
bass Sounds in the low audio
range, generally 20Hz–200Hz.
bit rate The number of bits per
second transmitted by a digital audio
or digital video signal. For example,
the bit rate of Dolby Digital is 384kbs
(384,000 bits per second) or
448kbs. MPEG-2 video encoding produces a digital video signal with a
variable bit rate that averages about
3.5Mbs (3.5 million bits per second).
Higher bit rates translate to better
audio and/or video quality.
bi-wire Connecting a loudspeaker
to a receiver or power amplifier with
two runs of cable to each of the positive and negative terminals. Possible
only with speakers featuring two pairs
of input terminals. Bi-wiring results in
better sound than single-wiring.
bass extension The lowest frequency an audio system can reproduce. A measure of how deeply an
audio system or loudspeaker will
reproduce bass. For example, a small
subwoofer may have bass extension
to 40Hz. A large subwoofer may have
bass extension to 16Hz.
bass management A combination of controls and circuits in an A/V
receiver or controller that determines
how bass frequencies are distributed
among the loudspeakers.
bass reflex A speaker with a hole
or slot in the cabinet that allows
sound inside the cabinet to emerge
into the listening room. Bass-reflex
speakers have deeper bass extension
than similarly sized speakers with
sealed cabinets, but that bass is generally less tightly controlled.
below black Information in a
video signal that falls below the technical threshold of black, 7.5 IRE.
Some DVD players pass signals that
are below black; others do not.
bi-amping Using two power
amplifiers to drive one loudspeaker.
One amplifier typically drives the
woofer, while the second drives the
midrange and tweeter.
big screen A large-screen directview television or rear-projection set.
black drop The black masking
area above and below a screen used
with a front-projection system.
black level Technically, the video
level that produces black in a video
display. Commonly, “black level”
refers to a video display’s ability to
present the color black as truly black
and not as dark gray.
Blu-ray Disc New optical disc format that can store 50GB on a duallayer disc the size of a DVD.
Competing with HD DVD to be the
high-definition replacement for DVD.
BNC jack A type of connector used
in high-end consumer and professional
A/V equipment. Used primarily for RGB
and component-video signals.
bridging Amplifier-to-loudspeaker
connection method that converts a
stereo amplifier into a monoblock
power amplifier. One amplifier channel amplifies the positive half of the
waveform, the other channel amplifies the negative half. The loudspeaker is connected as the “bridge”
between the two amplifier channels.
brightness In audio, an excessive
amount of treble that adds a shrillness to the sound. In video, the
amount of light generated by a video
display device.
brightness signal More correctly
called “luminance” and represented
by the letter Y, the brightness component of a video signal contains all the
black-and-white information. A complete color-video signal is a combination of luminance and chrominance
(color information).
burn-in Technically called “differential phosphor aging.” Phenomenon
that occurs in phosphor-based video
displays (CRT and plasma) in which
static images displayed on the screen
for long periods cause that static
image to be permanently superimposed on the screen.
CableCARD Credit-card-sized
device that inserts into a CableCARDcompliant television and replaces a
separate cable box.
calibration The act of fine-tuning
an audio or video component for correct performance. In an audio system,
calibration includes setting the individual channel levels. In video, calibration
means setting a video display device
to display the correct color, brightness,
tint, contrast, and other parameters.
cathode ray tube See “CRT.”
center channel In a multichannel
audio system, the audio channel that
carries information that will be reproduced by a speaker placed in the center of the viewing room between the left
and right speakers. The center channel
carries nearly all a film’s dialog.
center-channel mode A setting
on A/V receivers and A/V controllers
that configures the receiver or controller for the type of center-channel
speaker in the system.
center-channel speaker The
speaker in a home-theater system
located on top of, beneath, or behind
the visual image; reproduces centerchannel information such as dialog
and other sounds associated with
onscreen action.
chrominance (chroma) The
color-carrying portion of a video signal.
The chroma signal carries color and
hue, but little brightness information.
Class-A Mode of amplifier operation in which a transistor or tube
amplifies the entire audio signal.
Class-AB Mode of amplifier operation that is similar to Class-B except
that both tubes or transistors operate
when the voltage is near 0V.
Distortion is higher at low signal levels
than Class-A, but efficiency is higher,
though not as high as Class-B.
Class-B Mode of amplifier operation in which one tube or transistor
amplifies the positive half of an audio
signal, and a second tube or transistor amplifies the negative half.
Class-D Mode of amplifier operation in which the output transistors are
switched fully on or fully off in pulses.
The pulse duration determines the signal’s amplitude. Also called a “switching” or “digital amplifier.”
coaxial cable A cable in which
an inner conductor is surrounded by a
braided conductor that acts as a
shield. Coaxial cable is used between
a TV antenna and a VCR or TV,
between a DBS dish and a DBS
receiver, and sometimes between a
VCR and a TV set. It is also used to
deliver cable-TV signals into the home.
coaxial digital output A jack
found on most DVD players that provides a digital audio signal on an RCA
jack for connection to another component through a coaxial digital interconnect (which is different from the coaxial cable that carries TV signals).
coloration A change in sound
introduced by a component in an
audio system. A loudspeaker that is
“colored” doesn’t accurately reproduce
the signal fed to it. For example, a
speaker with coloration may have too
much bass and not enough treble.
channel balance The relative
levels or volumes of the different
channels in a home-theater system.
channel separation A measure
of how well sounds in one channel
are isolated from other channels. Low
channel separation results in sounds
from one channel “leaking” into other
channels, a phenomenon called
“crosstalk.” A classic example is frontchannel sounds in Dolby Surround
leaking into the surround channels.
High channel separation results in
more precise placement of sounds.
AVGuide.com Reprinted from Home Theater for Everyone by Robert Harley
color temperature
Measurement, in kelvins, of a video
display’s reproduction of gray. Too
low a color temperature and the color
gray has a red cast. Too high a color
temperature and the color gray has a
blue cast. The ideal color temperature
is represented as 6500K.
color uniformity The ability of a
projection screen to reflect all colors
equally at every point on the screen. A
screen with poor color uniformity may
impart a blue tint to the image on one
Glossary of A/V Terms (continued)
side of the screen, and a red tint on
the other side.
80Hz from the signal driving the main
speakers. Also called “cutoff frequency.”
color wheel In DLP-based video
displays, a device that sequentially
passes red, green, and blue light to
the DMD chip by means of a spinning wheel with red, green, and blue
filter wedges.
crossover slope Describes the
comb filter A circuit that splits a
composite video into separate color
and brightness signals.
component video A video signal
split into three parts: luminance and
two color-difference signals (technically known as Y, B–Y, R–Y, or YPbPr). A
superior method of connecting video
compared to composite video.
component-video switching
A feature on A/V controllers and
receivers that allows you to connect
several component-video sources to
the controller or receiver, with the controller or receiver sending the selected
signal to the video display.
steepness of a crossover filter.
Expressed as “dB/octave.” For example, a subwoofer with a crossover
frequency of 80Hz and a slope of
6dB/octave would allow audio frequencies at 160Hz (an octave above
80Hz) into the subwoofer, but signals at 160Hz would be reduced in
amplitude by 6dB. A slope of
12dB/octave would also allow
160Hz into the subwoofer, but the
amplitude would be reduced by
12dB. The most common crossover
slopes are 12dB/octave,
18dB/octave, and 24dB/octave.
Crossover slopes are also referred to
as “first-order” (6dB/octave), “second-order” (12dB/octave), “thirdorder” (18dB/octave), and “fourthorder” (24dB/octave). The “steeper”
slopes (such as 24dB/octave) split
the frequency spectrum more sharply
and produce less overlap between
the two frequency bands, but they
also cause phase anomalies.
composite video A video signal
in which the luminance (brightness,
or black-and-white) information and
the chrominance (color) information
are combined into a single signal.
Composite video inputs and outputs
appear on RCA jacks.
cone diaphragm The conically
shaped paper, plastic, or metal
diaphragm of a loudspeaker that
moves back and forth to create
sound. Contrast with “dome
diaphragm.”
congested A thickening of the
sound that makes instrumental
images less separate and distinct.
contrast The range between white
and black in an image.
crosstalk See “channel separation.”
CRT (cathode ray tube) A vacuum tube in which electrons are fired
at a screen coated with phosphors
that give off light when struck to produce a visible pattern (a picture).
Direct-view television sets use a large
CRT. Some front-projectors use three
small CRTs to project an image.
current The flow of electrons in a
conductor. For example, a power
amplifier “pushes” electrical current
through speaker cables and the voice
coils in a loudspeaker to make them
move back and forth.
deinterlacer A device that converts an interlaced video signal to a
progressive signal, and presents those
lines to a video display device at twice
the frequency of normal NTSC video.
deinterlacing Technique of converting an interlaced video image to a
progressive video image.
ments, voices, or sounds existing
behind one another in three dimensions, as in “soundstage depth.”
dialog intelligibility The ability
to clearly hear and understand the
dialog in a movie without strain.
Dialog intelligibility is affected by the
quality of components in a home-theater system, room acoustics, and
how the system is set up.
diaphragm The surface of a
loudspeaker driver that moves, creating sound.
diffraction The bending of sound
waves as they pass around an object.
Also a re-radiation of sound caused
by discontinuities in surfaces near the
radiating device, such as the bolts
securing drivers to a speaker cabinet.
diffusion Scattering of sound.
Diffusion reduces the sense of direction of sounds, which benefits sound
produced by surround loudspeakers.
digital Calculation or representation by discrete units. For example,
digital audio and digital video can be
represented by a series of binary
ones and zeros.
Digital Light Processing
(DLP) A technology developed by
preamplifier.
DAC See “digital-to-analog converter.”
convergence The integration of
various technologies, such as digital
video, digital audio, computers, and
the Internet.
data compression See “percep-
digital loudspeaker
tual coding.”
crossover A circuit that splits up
DBS See “direct broadcast satellite.”
Loudspeaker incorporating a digital
crossover and power amplifiers. A digital loudspeaker takes in a digital bitstream, splits up the frequency spectrum with digital signal processing,
converts each of those signals to analog, and amplifies them separately. The
individual power amplifiers then power
each of the loudspeaker’s drive units.
frequency.”
controller Another term for an A/V
the frequency spectrum into two or
more parts. Crossovers are found in
virtually all loudspeakers, and in
some A/V receivers and controllers.
crossover frequency The frequency at which the audio spectrum is
split. A subwoofer with a crossover frequency of 80Hz filters all information
above 80Hz from the signal driving the
subwoofer, and all information below
dB See “decibel.”
DC (direct current) Flow of
electrons that remains steady in one
direction rather than alternating directions. Contrasted with alternating current (AC).
decibel (dB) The standard unit
for expressing relative power or
amplitude levels.
digital signal processing
(DSP) Manipulation of audio or
video signals by performing mathematical functions on the digitally
encoded signal.
digital television See “DTV.”
depth The impression of instru-
Texas Instruments that reflects light
from hundreds of thousands of tiny mirrors on a semiconductor chip to project
an image. The chip itself is called a
Digital Micromirror Device (DMD).
cutoff frequency See “crossover
and converts them to analog as part
of the amplification process.
Digital Micromirror Device
(DMD) See “Digital Light
Digital Theater Systems
See “DTS.”
digital-to-analog converter
(DAC, D/A) A device that converts
digital signals to analog signals. CD
players, laserdisc players, DBS boxes,
and DVD players all contain digital-toanalog converters.
Digital Transmission Content
Protection (DTCP) An encryption technology that allows transmission of digital video and digital audio
between components in a home-theater system, but prohibits those signals from being recorded. Used with
FireWire (IEEE1394). Also called 5C
to acknowledge the five companies
that developed it.
digital video recorder (DVR)
A device that stores digital video on a
hard-disk drive. TiVo and ReplayTV
devices are DVRs.
Digital Visual Interface (DVI)
A wideband digital video interface that
can carry uncompressed high-definition video and control signals in the
same cable.
D-ILA (Direct Drive Image
Light Amplifier) A video display
technology used in rear-projection televisions and front projectors. D-ILA is
JVC's implementation of reflective LCD
technology called liquid crystal on silicon (LCoS).
dipolar speaker A loudspeaker
that produces sound from the rear as
well as from the front, with the front
and rear sounds out of phase with
each other. Dipoles are most often
used as surround speakers.
direct current See “DC.”
direct broadcast satellite
(DBS) A method of delivering highquality digital video into consumers’
homes via an 18-inch roof-mounted
dish. Previously known as digital
satellite system (DSS).
Processing.”
digital power amplifier An
amplifier that takes in digital signals
AVGuide.com Reprinted from Home Theater for Everyone by Robert Harley
director’s cut A version of a film
re-edited by the director for a premium
consumer release.
Glossary of A/V Terms (continued)
Direct Stream Digital (DSD)
A method of digitally encoding music
with a very fast sampling rate, but
with only 1-bit quantization.
Developed by Sony and Philips for
Super Audio CD (SACD).
Dolby Pro Logic II Introduced in
late 2001, Pro Logic II provides
superior decoding of two-channel
music and film sources compared
with Pro Logic.
Dolby Surround An encoding for-
direct-view Another name for a
conventional television set. Called
direct-view because you view the
image directly on the front of its picture tube.
mat that combines four channels (left,
center, right, surround) into two channels for transmission or storage. On
playback, a Dolby Pro Logic decoder
separates the two channels back into
four channels.
discrete Separate. A discrete digital
surround-sound format contains 5.1
channels of audio information that are
completely separate from each other;
contrasted with a matrixed surround
format such as Dolby Surround,
which mixes the channels together for
transmission or storage.
Dolby TrueHD Lossless audioencoding system developed for HD
DVD and Blu-ray Disc. Dolby TrueHD
can deliver high-resolution multichannel audio with perfect bit-for-bit accuracy to the source.
DLP See “Digital Light Processing.”
shaped paper, plastic, silk, or metal
diaphragm of a loudspeaker that
moves back and forth to create
sound. Normally used in tweeters.
Contrast with “cone diaphragm.”
DMD See “Digital Light Processing.”
Downmix converter A circuit
over which a loudspeaker distributes
its sound.
Dolby Digital A 5.1-channel discrete digital surround-sound format
used in movie theaters and consumer
formats. One of the surround formats
used on DVD.
Dolby Digital EX A surroundsound format that matrix-encodes a
“back-surround” channel into the left
and right surround channels of a 5.1channel Dolby Digital signal. This
back-surround channel is reproduced
by one or two loudspeakers located
directly behind the listening position.
Although Dolby Digital EX is the format’s official name, it’s often called
THX Surround EX because THX was
the exclusive licensor of the technology until late 2001. Jointly developed
by Lucasfilm THX and Dolby
Laboratories.
Dolby Digital Plus Higher-quality version of Dolby Digital developed
for HD DVD and Blu-ray Disc.
Dolby Pro Logic A type of Dolby
Surround decoder with improved performance over standard Dolby
Surround decoding. Specifically, Pro
Logic decoding provides greater channel separation and a center-speaker
output. A Dolby Pro Logic decoder
takes in a 2-channel, Dolby
Surround–encoded audio signal and
splits those signals up into left, center,
right, and surround channels. Nearly
all A/V receivers and A/V controllers
include Dolby Pro Logic decoders.
D-VHS A digital video-recording for-
DTS-ES Matrix A 5.1-channel
DVR See “digital video recorder.”
surround-sound format that includes a
rear surround channel that is matrixencoded into the left and right surround channels of a 5.1-channel signal. Unlike DTS ES Discrete, DTS ES
Matrix is not a true 6.1-channel format because the soundtrack is carried
in 5.1 channels.
DTS-HD Higher quality version of DTS
developed for HD DVD and Blu-ray Disc.
DTS Neo:6 Cinema A DTS
dome diaphragm The dome-
dispersion The directional pattern
channel is completely separate from
the left and right surround channels,
unlike DTS ES Matrix, which matrixencodes the third surround channel
into the existing left and right surround
channels of a 5.1-channel signal.
found in DVD players that converts the
5.1-channel discrete Dolby Digital
soundtrack into a 2-channel Dolby
Surround–encoded signal. A DVD
player’s downmix converter lets you
hear surround sound from DVD if you
don’t have a Dolby Digital decoder.
decoding technology for playing back
2-channel film-soundtrack sources
(such as television broadcasts and the
stereo audio channels from a VCR)
through 5.1 or 7.1 loudspeakers.
DTS Neo:6 Music A DTS decoding technology for playing back twochannel music sources (such as
stereo CDs and FM radio) through 5.1
or 7.1 loudspeakers.
DTV (digital television)
Method of encoding and transmitting
video as a stream of ones and zeros,
rather than as an analog signal.
mat that uses a conventional VHS tape
shell. D-VHS can store up to four hours
of high-definition video on one tape.
DVI See “Digital Visual Interface.”
dynamic range In audio, the difference in volume between loud and
soft. In video, the difference in light
level between black and white (also
called “contrast”).
Dynamic-range compressor
A circuit found in some Dolby
Digital¬-equipped receivers and controllers that reduces audio dynamic
range. A dynamic range compressor
can reduce the volume of peaks, or
increase the volume of low-level
sounds, or both. Useful for late-night
listening when you don’t want explosions to disturb other family members, but still want to hear low-level
sounds clearly.
equalizer A circuit that changes
the tonal balance of an audio program. Bass and treble controls are a
simple form of equalizer.
excursion The amount of backand-forth movement of a loudspeaker
diaphragm.
driver The actual speaker unit
inside a loudspeaker cabinet.
DV A digital video-interface format
DSD See “Direct Stream Digital.”
used primarily on camcorders. A simplified version of FireWire
(IEEE1394).
tion in digital displays in which dark
areas appear as solid blotches.
field The odd- or even-numbered
lines of a frame.
DVD A format that puts MPEG-
fill factor In a digital display
2–encoded digital video and Dolby
Digital (and possibly DTS) surround-sound audio on a disc the
size of a CD.
device, the ratio of pixel area to nonpicture areas between the pixels. The
higher the fill factor, the smootherlooking the image.
DVD-Audio A DVD-format disc
FireWire A wideband digital inter-
Content Protection.”
containing high-resolution multichannel or 2-channel digital audio.
D-Theater Copy-protection system
DVD-R A write-once recordable
proposed for the D-VHS digital videotape format.
DVD format.
face that can carry digital audio, digital video, computer data, and control
codes in a single cable composed of
three twisted pairs of wires. Officially
called IEEE1394 after the Institute of
Electrical and Electronics Engineers,
the body that developed the interface.
DSP See “Digital Signal
Processing.”
DSP room correction A technique of removing room-induced frequency-response peaks and dips with
digital signal processing.
DTCP See “Digital Transmission
DTS (Digital Theater
Systems) A discrete, digital surround-sound format used in movie
theaters and home-theater systems.
An alternative to Dolby Digital that
uses a higher bit rate. Also called
“DTS Digital Surround.”
DTS-ES Discrete A 6.1-channel
surround-sound format that includes a
rear surround channel in addition to
the conventional 5.1 channels. Called
“discrete” because the rear surround
DVD-RAM A re-writable DVD
recording format that is incompatible
with all other recordable DVD formats.
DVD-RW A re-writable DVD recording format.
DVD+R A write-once recordable
DVD format that is incompatible with
DVD-R and DVD-RW.
DVD+RW A re-writable DVD format that is incompatible with DVD-R
and DVD-RW.
AVGuide.com Reprinted from Home Theater for Everyone by Robert Harley
false contouring A picture distor-
fixed-pixel display A video display device that uses an array of fixed
pixels to create the image. Examples
include LCD, DLP, LCoS, and plasma.
Contrast with a CRT-based display
that has no fixed pixel structure.
fixed-pixel scaler An image
scaler that outputs only a single resolution to a fixed-pixel display. A range
of output resolutions is unnecessary
because the output resolution is facto-
Glossary of A/V Terms (continued)
ry set for the display with which the
scaler is used.
carries control data along with digital
audio and video in the same cable.
fL See “foot-lambert.”
harmonic distortion The pro-
flat A speaker that accurately reproduces the signal fed to it is called
“flat” because that is the shape of its
frequency-response curve.
duction of spurious frequencies at
multiples of the original frequency. A
circuit amplifying a 1kHz sine wave
will create frequencies at 2kHz (second harmonic), 3kHz (third harmonic), and so forth.
floorstanding speaker A
speaker that sits on the floor rather
than on a stand.
HDCP See “High-bandwidth Digital
Foley Sound effects added to a film
HD DVD New optical disc format
soundtrack, such as footsteps and
doors closing.
foot-lambert (fL) A measure of
that can store 30BGB on a dual-layer
disc the size of a DVD. Competing
with Blu-ray Disc to be the high-definition replacement for DVD.
the amount of light from a video display device.
HDMI see “High-Definition
Content Protection.”
Multimedia Interface”
forward A description of a sonic
presentation in which sounds seem
to be projected forward, toward the
listener.
HDTV (high-definition television) Refers generally to high-reso-
video or film.
lution television transmissions and
displays, which must exhibit a vertical
resolution of 720 or higher to qualify
as HDTV.
frame rate The rate at which
hertz (Hz) The unit of frequency;
frames are displayed, expressed in
frames per second (fps). The NTSC television frame rate is 29.97fps; movies
are shot and displayed at 24fps.
the number of cycles per second.
Kilohertz (kHz) is thousands of cycles
per second.
frame One complete picture in
HiFi Short for High Fidelity, the highfrequency Number of repetitions of
a repeating cycle per second.
Measured in hertz (Hz), or cycles per
second. An audio signal with a frequency of 1000Hz (1kHz) undergoes
1000 cycles per second.
frequency response A graphical
representation showing a device’s relative amplitude as a function of frequency.
front projector A video display
device that projects an image from a
distance onto a separate screen.
full-range speaker A speaker that
reproduces bass as well as midrange
and treble frequencies.
gain See “screen gain.”
quality audio format used in some
VHS videocassette recorders. A VHS
HiFi VCR can provide excellent sound
quality. Contrasted with VHS linear
tracks, which offer poor sound quality.
high-resolution digital audio
Generally regarded as digital audio
with a sampling rate greater than
48kHz and a word length longer
than 16 bits.
interpolation Filling in missing
home theater The combination of
high-quality audio and video in your
home.
HAVi (Home Audio/Video
interoperability) A FireWirebased technology for controlling various components of a home-theater
system as a single unit with one
remote control. This “interoperability” is
possible because the FireWire interface
information with a “best-guess” estimate.
in-wall speaker A speaker
Home THX A set of patents, technologies, and playback standards for
reproducing film soundtracks in the
home as the producer intended. THX
doesn’t compete with surround formats
such as Dolby Pro Logic or Dolby
Digital, but instead builds on them.
horizontal resolution A number that specifies the amount of fine
detail a video display can show (or a
video format can contain) in each
horizontal scanning line. In analog
formats such as VHS videotape and
CRT-based television sets, horizontal
resolution is expressed in TV Lines
(TVL). In digital formats and fixedpixel display devices, horizontal resolution is expressed in the number of
pixels per horizontal line of video. For
example, VHS has a horizontal resolution of 240 TVL, DVD has a horizontal resolution of 720 pixels, and
HDTV’s maximum horizontal resolution is 1920 pixels. Technically, horizontal resolution is specified as the
number of pixels or TVL per picture
height. This requirement prevents
widescreen formats from having an
apparently higher horizontal resolution than 4:3 formats.
mounted inside a wall.
inverse telecine See “3:2 pulldown.”
IRE (Institute of Radio
Engineers) The measure of brightness in video images. Black is usually defined as 7.5 IRE; white as 100
IRE, with all other brightness levels
falling between these two values.
IR repeater A pair of devices,
called an “IR sensor” and “IR flasher,”
that together relay IR commands from
a remote control to components hidden from the remote control’s direct
line of sight.
kbps (kilobits per second)
Thousands of bits per second; a
measure of bit rate.
keystoning A picture distortion in
front projectors in which the top or
bottom of the picture is narrower than
the opposite edge. Arises from nonperpendicular placement of the projector with respect to the screen.
High-bandwidth Digital
Content Protection (HDCP)
Hz See “hertz.”
laserdisc A format for storing analog video signals on a 12-inch double-sided disc.
An encryption technique that allows
transmission of digital video and digital audio between components in a
home-theater system, but prohibits
those signals from being recorded.
Used with the DVI and HDMI interfaces.
IC (integrated circuit) Many
LCD (liquid crystal display)
A/V products use ICs for processing
and amplifying audio signals; higher-quality units use discrete transistors instead.
A technology for displaying images.
Light is projected through an array
of crystals that either pass or block
light, according to the signal driving
the panel.
High-Definition Multimedia
Interface (HDMI) Digital inter-
IEEE1394 See “FireWire.”
LCD projector A projector using
i.LINK Sony’s name for their imple-
three LCD panels and a light source.
face that can carry HD video, highresolution digital audio, and control
information on a single cable.
mentation of IEEE1394 (FireWire)
impedance Resistance to the flow of
an alternating electrical current.
LCoS (liquid crystal on silicon) A technology for displaying
high-definition television
infrared (IR) The wavelength of
see “HDTV”
light used by remote controls to send
commands to components.
grayscale tracking A measurement of a video display’s performance
that reveals the display’s ability to
produce the color gray at the correct
color temperature (6500K) at varying
brightness levels.
bered scanning lines are displayed
on the second pass, to form a complete image. Contrast with “progressive scanning.”
high-density layer The information layer in a Super Audio CD that
contains high-resolution digital audio.
high-pass filter A circuit that allows
high frequencies to pass, but blocks
low frequencies. Also called a “lowcut filter.” High-pass filters are often
found in A/V receivers and A/V controllers to keep bass out of the main
speakers when using a subwoofer.
interconnect A cable that carries
line-level audio signals.
interlaced scanning The technique used in NTSC video in which
the odd-numbered scanning lines of
the video picture are displayed in
one pass from the top of the screen
to the bottom, and the even-num-
AVGuide.com Reprinted from Home Theater for Everyone by Robert Harley
images. Used in rear-projection televisions and front projectors. Similar to
LCD, but in LCoS, light is selectively
reflected from pixels in the LCoS
panel. (By contrast, LCD is a “transmissive” technology in which light
passes through the pixels rather than
being reflected by them.)
letterbox A video image that
results from displaying an image of
widescreen aspect ratio on a television set of standard aspect ratio. The
picture is presented between black
Glossary of A/V Terms (continued)
bars above and below the image.
Contrast with “windowbox.”
LFE See “Low Frequency Effects.”
linear tracks The audio tracks recorded on VHS tape as thin stripes along
the tape edge. Recorded and played
back by a stationary head. The slow
tape speed of VHS results in poor
sound quality. Different from HiFi
tracks, in which the audio is recorded
along with the video by the spinning
video head for higher audio quality.
line level An audio signal with an
amplitude of approximately 1V to 2V.
Audio components interface at line
level through interconnects.
Contrasted with “speaker level,” the
much more powerful signal that
drives speakers.
Mbps (mega bits per second) Million bits per second. A unit
of measure for expressing bit rates.
For example, MPEG-2 video encoding
has a variable bit rate that averages
3.5Mbps.
microdisplay A rear-projection
video display based on a fixed-pixel
technology such as DLP, LCoS, or LCD.
midrange Audio frequencies in the
middle of the audible spectrum, such
as the human voice. Generally the
range of frequencies from about
200Hz to 2kHz. Also: a driver in a
loudspeaker that reproduces the range
of frequencies in the middle of the
audible spectrum.
millisecond (ms) One onethousandth (0.001) of a second.
liquid crystal display
See “LCD.”
modular A/V controller An A/V
liquid crystal on silicon
controller built with interchangeable
modules for upgrading to future technologies.
See “LCoS.”
LNB (Low-Noise Blocking
Converter) A device inside a DBS
dish that picks up the transmitted digital video signal.
localization The ability to detect
the directionality of sounds.
monoblock A power amplifier with
only one channel.
motorized masking A projection
screen in which a motor-driven black
drop moves into position over the
screen to create different aspect ratios.
low-cut filter A circuit than
removes bass frequencies from an
audio signal. Also called a “highpass filter.”
motorized screen A projection
screen that retracts by motor drive into
a housing when not in use.
Low Frequency Effects (LFE)
motion artifacts Visible defects
in a displayed image resulting from
motion of objects within the image.
A separate channel in the Dolby
Digital format reserved for low-bass
effects, such as explosions. The LFE
channel is the “.1” channel in a 5.1channel format.
low-noise blocking converter
MP3 A perceptual coding format
that reduces the number of bits
required to represent a digital audio
signal. Shorthand for MPEG-1 Audio
Level 3.
See “LNB.”
low-pass filter A circuit that
MPEG (Motion Picture
Experts Group) The body that
removes midrange and treble frequencies from an audio signal. Also called
a “high-cut filter.”
develops data-compression standards
for audio and video. Pronounced
“em-peg.”
loudspeaker A device that converts
an electrical audio signal into sound.
The loudspeaker is the last component
of the audio playback chain.
MPEG-1 video compression
luminance The black-and-white,
or brightness, component of a video
signal. Represented by the letter Y.
masking The blacked-out areas to
the sides of a front-projection screen.
that produces higher-quality pictures at
standard MPEG-2 bit rates, and highdefinition pictures at bit rates of
7–10Mbps. Adopted for use in HD DVD
and Blu-ray Disc as well as in the next
generation of satellite transmission.
Results in the left and/or right edges
of the image being cut off.
MTS (Multichannel
Television Sound) The method
passive subwoofer A speaker
for reproducing bass frequencies that
must be powered by a separate power
amplifier. Contrasted with “active” or
“powered” subwoofers, which contain
built-in amplifiers.
of broadcasting stereo audio over
conventional television channels.
PCM See “Pulse Code Modulation.”
multichannel power amplifier
peak A short-term, high-level audio
A power amplifier with more than two
channels, usually five or six.
signal.
perceptual coding A method of
multichannel sound Sound
reproduction using more than two
channels feeding more than two
loudspeakers.
multipath In FM-radio or television transmission, interference
caused by the signal traveling two or
more paths to travel between transmitter and receiver. Multipath is
caused by mountains or buildings
that reflect the radio or TV signals;
the receiving antenna picks up the
directly broadcast signal along with
the signal after it has been delayed
by the reflections. Multipath introduces audible distortion in FM tuners,
and in television transmission is seen
as “ghosting” in the picture. Multipath
can cause HDTV receivers to pick up
no usable signal.
multiroom A feature on some A/V
products that lets you listen to two different sources in two different rooms.
notch filter A circuit found in inexpensive television sets in place of a
comb filter; separates the brightness
and color portions from a compositevideo signal.
NTSC (National Television
System Committee) The body
that set the American color TV standard in 1953. NTSC has become a
descriptive name for television and
video signals that conform to this
standard. Jokingly referred to as
“Never Twice the Same Color.”
reducing the number of bits needed to
encode an audio or video signal by
ignoring information unlikely to be
heard or seen. Also called “lossy
compression.”
phantom center-channel
mode A setting on A/V receivers or
A/V controllers invoked when no center-channel speaker is used.
phantom image The creation of
an apparent sound source between
two speakers.
phase In a periodic wave, the fraction of a period that has elapsed.
Describes the time relationship
between two signals.
phase adjustment A control provided on some subwoofers that lets
you delay the sound of the subwoofer
slightly so that its output is in phase
(has the same time relationship) with
the output of the front speakers.
pixel The smallest element in a displayed video image. Image resolution is
measured in pixels; the greater the number of pixels, the higher the resolution.
plasma display panel (PDP)
Fixed-pixel video display device in
which an electrical charge ionizes gas
inside a glass-matrix array, causing
phosphors on the glass to emit light.
Current plasma panels range in size
from 42 to 71 inches, and are about
three inches thick.
A video encoding method that reduces
the bit rate needed to represent the
video signal to 1.4Mbps. Provides
poor picture quality.
panning The side-to-side movement of sounds and images from one
location to another. Originally a camera term.
port Opening in a loudspeaker cabinet that channels bass from inside the
enclosure to outside the enclosure.
Also called a “vent.”
MPEG-2 video compression
pan&scan A method of converting
power amplifier An audio com-
A much-higher-quality encoding technique than MPEG-1. Used in DBS
and DVD.
a widescreen presentation to an
image within a 4:3 aspect ratio without black bars at the top and bottom
of the picture. The camera moves
back and forth (panning and scanning) in each scene to show only the
most important parts of the image.
ponent that boosts a line-level signal
to a powerful signal that can drive
loudspeakers.
matrix A method of encoding mul-
MPEG-4 video compression
tiple audio channels into two channels for transmission or storage.
Also called Advanced Video Coding
(AVC). A video compression algorithm
AVGuide.com Reprinted from Home Theater for Everyone by Robert Harley
power handling A measure of
how much amplifier power, in watts, a
speaker can take before it is damaged.
Glossary of A/V Terms (continued)
power output A measure of a
power amplifier’s ability, in watts, to
deliver electrical voltage and current
to a speaker.
power supply Circuitry found in
every audio and video component
that converts 60Hz alternating current
from the wall outlet into direct current
that supplies the device’s circuitry.
re-equalization A Home THX
technology that reduces the amount of
treble on playback so that you hear a
more natural-sounding reproduction
when a film soundtrack is played
back in the home.
resistance A measure of how
strongly a circuit impedes the flow of
a direct current.
power transformer Device in a
resolution The quality of an
power supply that reduces the
incoming voltage from 120V to a
lower value.
audio component that reveals lowlevel musical information; the
amount of fine detail in a video display or video source.
progressive scanning A
method of creating an image on a
video monitor by displaying the scanning lines sequentially from top to
bottom. Contrast with “interlaced
scanning.”
RGB A video transmission format
similar to component video; separates
color video images into red, green, and
blue parts. Carried on three cables.
RGBHV RGB video transmission
pulse code modulation
(PCM) A method of representing an
audio signal as a series of digital
samples.
format with the horizontal (H) and
vertical (V) synchronization signals
carried on separate cables. Carried on
five cables.
quantization Assigning a series
RG-6 coaxial cable A higher-
of discrete numerical values to an
analog waveform. In digital audio, the
analog waveform’s amplitude is converted to a number (quantized) each
time a sample is taken.
quality version of RG-59.
RG-59 coaxial cable A type of
cable that carries television or cableTV signals.
nal. In the NTSC system, each video
frame is composed of 525 scanning
lines (of which 480 are visible).
scan rate The frequency with
which a video display device
“paints” scan lines. NTSC video has
a scan rate of 15,734 lines per second (525 lines per frame multiplied
by 29.97 frames per second), or
15.734kHz.
screen The front of a direct-view
television’s CRT picture tube, the front
of a rear-projection TV onto which an
image is projected, or a separate
material onto which a front projector
projects a video image.
between the actual analog value and
the number representing that analog
value. Quantization error occurs when
the analog value falls between two
quantization steps; the quantizer
assigns the closest number.
Quantization error introduces noise
and distortion in digital audio, often
heard as a roughness at low signal
levels, particularly during reverberation decay.
RPTV See “rear-projection TV.”
SACD See “Super Audio CD.”
sampling The process of converting an analog audio signal into digital form by taking periodic “snapshots” of the audio signal at some
regular interval. Each snapshot
(sample) is assigned a number that
represents the analog signal’s
amplitude at the moment the sample
was taken.
quantization word length The
number of bits created by the A/D
converter at each sample point.
Compact Disc records quantization
words 16 bits in length.
radiation pattern The way in
which a speaker disperses sound.
RCA jack A connector found on
audio and video products. Signals
transmitted via RCA jacks include
line-level audio, composite video, and
component video.
rear-projection TV (RPTV)
A video display device that projects
an image onto a screen mounted at
the front of the cabinet. The image
can be generated by various technologies, including CRT, DLP, LCD,
and LCoS.
sampling frequency The rate at
which samples are taken when converting analog audio to digital audio.
Expressed in samples per second, or,
more commonly, in hertz; i.e., the CD
format’s sampling frequency is
44.1kHz.
satellite speaker A small loudspeaker with limited bass output,
designed to be used with a subwoofer.
scaler Video processing device that
changes the resolution of the input
signal to a different resolution.
scan line One sweep of a beam of
electrons from left to right across a
CRT display; also, one horizontal line
of picture information in a video sig-
Numerical value expressing in decibels the difference in level between an
audio component’s noise floor and
some reference signal level.
single-chip DLP A DLP-based
video display in which a single DMD
creates the image. A single-chip
device projects the three primary colors of red, green, and blue sequentially. Contrast with three-chip products
in which the three colors are projected
simultaneously.
soundfield See “soundstage.”
sound-pressure level (SPL) A measure of loudness. Expressed in decibels (dB SPL).
screen gain A measure of a
screen’s reflectivity compared with a
reference material. Screen gains of
more than 1.0 are possible because
some screens focus their reflected
light over a narrow viewing area.
SDI (serial digital interface)
A digital video interface that carries
standard-definition video signals, but
not high-definition, mostly in very
high-end and professional video
equipment. HD SDI carries high-definition video.
selectivity Tuner specification
quantization error Difference
signal-to-noise ratio (S/N)
describing the tuner’s ability to reject
unwanted stations. Good selectivity is
important to those who live in cities,
where stations are closely spaced on
the broadcast spectrum.
soundstage The impression of
soundspace existing in three dimensions in front of and/or around the listener.
source components A/V components that provide audio and video
signals to the rest of a home-theater
system. Digital video recorders, DBS
dishes and receivers, and DVD players are source components.
source switching Function performed by an A/V receiver or A/V controller that selects which source component’s signals are fed to the speakers and video monitor.
spade lug A speaker termination
with a flat area that fits around a
binding post.
SED See “Surface-conduction
Electron-emitter Display.”
sensitivity A measure of how
much sound a speaker produces for a
given amount of input power. Speaker
sensitivity is measured by driving a
speaker with 1W of power and measuring the sound-pressure level from a
distance of 1 meter.
set-top box (STB) A device that
receives and decodes digital television
signals. A set-top box can also
include a satellite receiver and/or a
hard-disk-based digital video recorder
(DVR).
S/PDIF (Sony/Philips Digital
Interface Format) Standardized
method of transmitting digital audio
from one component to another.
SPL See “sound-pressure level.”
speaker See “loudspeaker.”
SPL meter A device for measuring
the sound pressure level created by
an audio source.
spring clips Cheap speaker terminations found in budget A/V receivers.
STB See “set-top box.”
shielded loudspeaker A loudspeaker lined with metal to contain
magnetic energy inside the speaker.
Shielded loudspeakers are used in
home theater because the speaker’s
magnetic energy can distort a video
monitor’s picture.
subwoofer A speaker designed to
reproduce low-bass frequencies.
sibilance s, sh, and ch sounds in
spoken word or singing.
Surface-conduction Electronemitter Display (SED) Display
AVGuide.com Reprinted from Home Theater for Everyone by Robert Harley
Super Audio CD (SACD) Disc
format that can deliver high-resolution multichannel or 2-channel digital audio.
technology developed by Canon and
Glossary of A/V Terms (continued)
Toshiba that delivers a CRT-quality
picture in a flat-panel form-factor.
surround decoder A circuit or
component that converts a surroundencoded audio signal into multiple
audio signals that can then be amplified. A Dolby Digital decoder takes in
an encoded Dolby Digital signal and
outputs a 5.1-channel (left, center,
right, left surround, right surround,
subwoofer) audio signal.
terminations The fittings on the
transcoder A device that converts
end of a cable: RCA plugs, spade
lugs, banana plugs, etc.
video from one format to another,
such as VGA to component video.
THD See “Total Harmonic
Distortion.”
transient A short-lived sound,
often at high level. The sound of a
snare drum is an example of a musical transient.
three-chip DLP A DLP-based
surround decorrelation A THX
technology that makes the sound in
the monophonic left and right surround channels in a Dolby Surround
signal slightly different.
video display in which the image is
created by three separate DMDs, one
each for the three primary colors of
red, green, and blue. Three-chip
devices project the three colors
simultaneously. All LCD and LCoS
displays use three panels. Contrast
with single-chip DLP in which the
three primary colors are projected
sequentially.
surround delay A technique of
throw distance The distance
delaying the signal to the surround
channels to increase the apparent
separation between the front and surround channels.
between a front projector and the
screen.
surround mode A setting on A/V
receivers and A/V controllers that
determines what surround decoding
or signal processing is performed on
the audio signal.
surround receiver
See “A/V receiver.”
surround speakers Speakers
located beside or behind the listener
that reproduce the surround channels of surround-sound¬–encoded
audio programs.
S-VHS A variant of the VHS tape
format that provides better picture
quality by storing the video signal
with a wider bandwidth, and by keeping the video signal’s brightness and
color information separate.
S-video A video connection
method that keeps the video signal’s
brightness and color information separate. Uses a 4-pin DIN connector.
SXRD (Silicon X-tal
Reflective Display) Sony’s
trade name for its video display technology based on LCoS. “X-tal” is cute
shorthand for “crystal.”
system matching The art of
combining components to create the
most musical system for a given
budget.
treble High audio frequencies, generally the range from 3kHz to 20kHz.
tweeter A speaker driver designed
to reproduce treble signals.
2-way speaker A loudspeaker
that splits the frequency spectrum into
two parts (bass and treble) for reproduction by two or more drivers.
THX A set of patents, technologies,
and technical/acoustic performance
criteria for film-sound reproduction
in movie theaters; see also “Home
THX.”
THX-certified An A/V product that
correctly implements the THX technologies and meets stringent technical
performance criteria for film-sound
reproduction.
unbalanced connection
Connection method in which the
audio signal is carried on two conductors, called signal and ground.
Contrast with balanced connection, in
which the audio signal is carried on
three conductors.
upconvert Changing a video sig-
for Dolby Digital EX.
nal from one scanning rate to a signal
with a higher scanning rate. HD-ready
televisions upconvert 480i signals to a
higher scanning rate for display.
timbre The tonal quality or charac-
user interface The “look” and
teristic of a sound.
“feel” of the controls and displays on
a home-theater product.
surround sound An audio
recording and playback format that
uses more than two channels, and is
reproduced with two or more loudspeakers located behind the listener in
addition to the loudspeakers in front.
transistor Device made from solid
semiconductor material that can
amplify audio signals.
THX Surround EX Original name
timbre matching A THX technology that ensures sounds arriving from
the listener’s sides have the same
timbres as sounds arriving from the
front, in order to ensure smooth panning of sounds.
time shifting Recording a television or DBS program for later playback.
vertical resolution The number
of scanning lines presented by a
video display from the top of the
image to the bottom; the number of
scanning lines in a video signal.
NTSC video has a vertical resolution
of 480 lines; HDTV has a vertical resolution of 720 or 1080 lines.
tonal balance Relative levels of
bass, midrange, and treble in an audio
component or audio presentation.
video display A device that con-
TosLink A fiber-optic-based con-
video monitor A video display
with video input and output jacks but
no television tuner.
nection for carrying digital audio.
Many DVD players have a TosLink
digital output.
verts a video signal into a visual
image.
video upconverter Device or
Total Harmonic Distortion
(THD) A measure of all the harmonic distortion components (i.e.,
second harmonic, third harmonic,
etc.) produced by an audio device,
expressed as a percentage of the fundamental signal. Called “total”
because it is the sum of all the individual harmonic-distortion components created by the component.
circuit within a device that converts a
lower-resolution video signal to a
high-resolution video signal.
voice coil Coil of wire inside a
loudspeaker driver through which current from the power amplifier flows.
volt Unit of electromotive force.
One volt is defined as the differ-
AVGuide.com Reprinted from Home Theater for Everyone by Robert Harley
ence in potential required to make
one ampere of current flow
through one ohm of resistance;
see also “voltage.”
voltage Analogous to electrical
pressure. Voltage exists between two
points when one point has an
excess of electrons in relation to the
other point. A battery is a good
example: the negative terminal has
an excess of electrons in relation to
the positive terminal. If you connect
a piece of wire between a battery’s
positive and negative terminals, voltage pushes current through the wire.
Current flow is the electron charge in
motion through the conductor. One
volt across 1 ohm of resistance produces a current of 1 ampere.
watt The unit of electrical power,
defined as the power dissipated by 1
ampere of current flowing through 1
ohm of resistance.
wavelength The distance between
successive cycles of a periodic wave.
widescreen A video display or
projected image with an aspect ratio
wider than 1.33. Widescreen TVs
have an aspect ratio of 1.78, also
expressed as “16:9.”
windowbox A video image that
results from displaying an image of
standard (1.33) aspect ratio on a television set of widescreen (1.78)
aspect ratio. The picture is presented
between black bars to the left and
right sides of the image. Contrast
with “letterbox.”
XLR jack and plug 3-pin connector that usually carries a balanced
audio signal. Can also carry a 2channel digital audio signal.
YCbCr The technical term for digital
component video. The letter “Y” represents the luminance (brightness) portion of the component-video signal,
and “Cb” and “Cr” are the color-difference signals.
YPbPr The technical term for analog component video. The letter “Y”
represents the luminance (brightness)
portion of the component-video signal, and “Pb” and “Pr” are the colordifference signals.
zone plate A special video test
pattern that’s useful for assessing a
video display’s comb filter, as well
as the 3:2 pulldown performance of
progressive-scan DVD players and
image scalers within video displays.
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