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Home Theater - Movies Glossary
Category: Film and Animation > Home Theater's AV Glossary
Date & country: 19/08/2008, US
Words: 229


FM
Frequency Modulated.

Frequency
The number of cycles (vibrations) per second. In audio, audible frequencies commonly range from 20 to 20,000 cycles per second (Hz). In video, frequency is used to define the image resolution. Low-frequency video images depict large objects or images. Higher frequencies depict smaller objects (finer details).

Frequency Response
A measure of what frequencies can be reproduced and how accurately they are reproduced. A measurement of 20 to 20,000 Hz ± 3dB means those frequencies between 20 and 20,000 Hz can be reproduced no more than 3 dB above or below a reference frequency level.

Full-Range
A speaker designed to reproduce the full range (20 Hz to 20 kHz) of audio frequencies.

Gain
Increase in level or amplitude.

Graphic Equalizer
A type of equalizer with sliding controls that create a pattern representing a graph of the frequency-response changes. Raising sliders boosts the affected frequencies; lowering sliders cuts (attenuates) the affected frequencies.

Gray Scale
The ability for a video display to reproduce a neutral image color with a given input at various levels of intensity.

Hanging Dots
An artifact of composite video signals that appears as a stationary, zipper-like, horizontal border between colors.

HDCP
High-Bandwidth Digital Content Protection. Created by Intel, HDCP is used with HDTV signals over DVI and HDMI connections and on D-Theater D-VHS recordings to prevent unauthorized duplication of copyright material.

HDMI
HDTV connection format using a DVI interface that transfers uncompressed digital video with HDCP copy protection and multichannel audio.

HDR
Hard-Drive Recorder. Device that uses a computer hard drive to store compressed digital audio and video signals.

HDTV
High-Definition Television. The high-resolution subset of our DTV system. The FCC has no official definition for HDTV. The ATSC defines HDTV as a 16:9 image with twice the horizontal and vertical resolution of our existing system, accompanied by 5.1 channels of Dolby Digital audio. The CEA defines HDTV as an image with 720 progressive or 1080 inter...

Hi-Fi Stereo
Feature found on VCRs that records or plays back stereo soundtracks with improved fidelity compared to using the linear stereo tracks.

High Gain Screen
Material that reflects more light than a reference material. Increases a projector's light output at the expense of uniformity.

High Pass
A filter that passes high frequencies, and attenuates low frequencies. Same as low cut.

Home Theater in a Box
A complete home theater system in one box (or at least sold together as a package). Consists of five or more speakers, a subwoofer, and a receiver. May also include a DVD player.

Horn
A type of speaker that looks like a horn. These speakers have small drivers and very large mouths; the horn shape serves to transform the small radiating area of the driver into the much larger radiating area of the mouth of the horn.

Hz
Hertz or cycles per second. Something that repeats a cycle once each second moves at a rate of 1 Hz.

IEEE 1394
Networking standard for PCs. Combined with 5C copy protection, is used as a two-way connection to transfer the MPEG-compressed digital bitstreams between consumer electronics items, including HDTV tuners and displays, D-VHS recorders, DVD players, and DBS receivers. Also called FireWire, iLink, ...

iLink
See IEEE 1394.

Imaging
The ability to localize the individual sound sources in three-dimensional space.

Impedance
A measure of the impediment to the flow of alternating current, measured in ohms at a given frequency. Larger numbers mean higher resistance to current flow.

Integrated Amplifier
A combination preamp and amplifier.

Interconnects
Any cable or wire running between two pieces of A/V equipment. For example, RCA terminated cables connecting pre/pros and amps.

Interlace
Process of alternating scan lines to create a complete image. In CRT displays, every second field/frame is scanned between the first field/frame. The first field represents 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 blurs the two fields together and sees the...

Inverted Dome
A type of speaker-driver shape; usually used for tweeters (concave).

Isobarik
Also known as compound loading. By using two low frequency drivers (generally mounted face-to-face and wired electrically out-of-phase or mounted front-to-back in a shallow tube and wired electrically in phase) you can halve the volume of the cabinet without reducing the low frequency extension of the subwoofer.

Keystone
A form of video image distortion in which the top of the picture is wider than the bottom, or the left is taller than the right, or vice versa. The image is shaped like a trapezoid rather than a rectangle.

kHz
Kilohertz or one thousand Hz.

Laser Disc
Now-defunct 12-inch disc format with excellent analog, FM-recorded video image, and either analog or CD-quality PCM-encoded audio. Later discs used one of the analog channels to record an RF-modulated Dolby Digital/AC3 soundtrack and/or used the PCM tracks to encoded a DTS soundtrack.

LCD
Liquid Crystal Display. A display that consists of two polarizing transparent panels and a liquid crystal surface sandwiched in between. Voltage is applied to certain areas, causing the crystal to turn dark. A light source behind the panel transmits through transparent crystals and is mostly blocked by dark crystals.

LCOS
Liquid Crystal on Silicon

Letterbox
Format used widely on laser disc and many DVDs to fit wide-aspect-ratio movies (1.85:1 and 2.35:1, for example) into a smaller frame, such as the 1.78:1 area of an anamorphic DVD or the 1.33:1 area of a laser disc or video tape. The image is shrunk to fit the screen, leaving blank space on the top and bottom. This process sacrifices some vertical d...

LFE
Low Frequency Effects track. The .1 channel of a Dolby Digital, DTS, or SDDS soundtrack. The LFE is strictly low-frequency information (20 to 120 Hz, with 115 dB of dynamic range) that's added to the soundtrack for extra effect. This track does not inherently contain all the bass of the soundtrack.

Line-Level (Low-Level)
A level of electrical signals too low to make the average speaker move sufficiently. Amplifiers receive line-level signals and amplify them to speaker level.

LNB
Low-Noise Blocker. The receiving end of a satellite dish.

Low Pass
A filter that lets low frequencies go through but doesn't let high frequencies go through. Same as high cut.

Luminance
The black and white (Y) portion of a composite, Y/C, or Y/Pb/Pr video signal. The luminance channel carries the detail of a video signal. The color channel is laid on top of the luminance signal when creating a picture. Having a separate luminance channel ensures compatibility with black-and-white televisions.

Megachanger
CD or DVD player with massive disc storage capacity, holding 50 or more discs.

MHz
Megahertz, or 1 million Hz.

Midbass
The middle of the bass part of the frequency range, from approximately 50 to 100 Hz (upper bass would be from 100 to 200 Hz). Also used as a term for loudspeaker drivers designed to reproduce both bass and midrange frequencies.

Midrange
The middle of the audio frequency range. Also used as a term for loudspeaker drivers designed to reproduce this range.

MLP
Meridian Lossless Packing. Encoding format that is able to completely reconstruct the original signal at the receiving end. No information is lost or discarded, regardless of how trivial it might be. Used to encode six channels of high-resolution audio on DVD-A.

Mono
Monophonic sound. One channel.

MP3
MPEG-1 Audio Layer-3. Compression scheme used to transfer audio files via the Internet and store in portable players and digital audio servers.

Multiple-Rate Encoding
Instead of locking encoding at a certain constant data rate, it allows the codec to choose whatever rate is best for that portion of the recording. Usually reduces file size with proportionally less loss in quality.

Multiroom
System that provides audio or video to multiple areas. Usually with only one source.

Multisource
System with multiple sources. Can also be used to describe a receiver that can provide multiple different sources into different rooms.

Multizone
System that provides different sources into multiple areas simultaneously.

Negative Gain Screen
Material that reflects less light than a reference material. Often used for DLP and LCD projection systems.

Noise
An unwanted portion of a signal such as hiss, hum, whine, static, or buzzing.

NTSC
National Television Standards Committee. Government-directed committee that established the U.S. color TV standard in 1953. Also known, sarcastically, as Never Twice the Same Color or Never The Same Color due to the inherent difficulty in achieving proper color calibration.

Octave
The difference between two frequencies where one is twice the other. For example, 200 Hz is an octave higher than 100 Hz. 400 Hz is one octave higher than 200 hz.

Ohm
A measure of how much something resists (impedes) the flow of electricity. Larger numbers mean more resistance.

Optical Digital Cable
Fiber optic cable that transfers digital audio signals as light pulses.

Parametric
Equalizer with adjust-able parameters, such as center frequency and bandwidth (Q), as well as amplitude.

Passive
Not active. A passive crossover uses no external power and results in insertion loss. A passive speaker is one without internal amplification.

Passive Radiator
A radiating surface (usually similar to a conventional speaker cone) that is not electrically driven but shares the same air space in a sealed cabinet with an electrically driven loudspeaker. This arrangement is functionally similar to a loudspeaker with a vented (ported) cabinet, with the passive radiator serving the duties of the air in the port.

PCM
See Pulse Code Modulation.

Phase
Time relationship between signals; it's all relative.

Piezo
A type of speaker driver that creates sound when a quartz crystal receives electrical energy.

Pixel
Contraction of picture element. The smallest element of data in a video image.

Plasma
Flat-panel display technology that ignites small pockets of gas to light phosphors.

Port
An aperture in a loudspeaker enclosure that helps extend the usable low-frequency output. A ported enclosure is also called vented or bass reflex.

Power Amp
See Amplifier.

Power Output
A measure, usually in watts, of how much energy is modulated by a component.

Pre Outs
Connectors that provide a line-level output of the internal preamp or surround processor.

Pre Outs/Main Ins
Connectors on a receiver that provide an interruptible signal loop between the output of the internal preamp or surround processor portion of the receiver and the input of the amplifier portion of the receiver.

Pre/Pro
A combination preamp and surround processor.

Preamplifier
A control and switching component that may include equalization functions. The preamp comes in the signal chain before the amplifiers.

Processors
Anything that processes an incoming signal in some way. Surround processors, for example, can decode a Dolby Digital signal to send to an amp so you can hear it.

Progressive Scanning
Each frame of a video image is scanned complete, from top to bottom, not interlaced. For example, 480p means that each image frame is made of 480 horizontal lines drawn vertically. Computer images are all progressively scanned. Requires more bandwidth (twice as much vertical information) and a faster horizontal scan frequency than interlaced images...

Projection System
Display that projects image onto a screen.

Pulse Code Modulation
(PCM) a way to convert sound or analog information to binary information (0s and 1s) by taking samples of the sound and record the resulting number as binary information. Used on all CDs, DVD-Audio, and just about every other digital audio format. It can sometimes be found on DVD-Video.

PVR
Personal Video Recorder. Marketing term for Video HDRs.

RCA Jacks
Receptacles for coaxial cables carrying line-level audio signals. Also called phono-type connectors.

Re-EQ
Short for Re-equalization. A feature found on THX-certified receivers and pre/pros. Movie soundtracks are mixed for theaters or far-field monitors with an expected high-frequency roll-off otherwise known as an X-curve. If these soundtracks are not re-mixed for home use, they will sound too bright when played back through home speakers or near-field...

Rear-Projection Television
Display that projects an image on the backside of a screen material, usually after having been reflected off of a mirror.

Receiver
Any component that receives, or tunes, broadcast signals, be it NTSC, HDTV, DBS, or AM/FM radio. Typically refers to the single component that includes a preamp, surround processor, multichannel amplifier, and AM/FM tuner.

Resonant Frequency
The frequency at which any system vibrates naturally when excited by a stimulus. A tuning fork, for example, resonates at a specific frequency when struck.

Reverberation
The reflections of sound within a closed space.

Reverberation Time
The amount of time it takes the reverberation to decay 60 dB from the level of the original sound.

RF
Radio Frequency. Television signals are modulated onto RF signals and are then demodulated by your television's tuner. VCRs and DBS receivers often include channel 3 or 4 modulators, allowing the output signal to be tuned by the television on those channels. Also, laser discs used an RF signal for modulating Dolby Digital 5.1 soundtracks on some mo...

RGB
Red, Green, Blue. Can refer to an unprocessed video signal or the color points of a display device. Together these three colors make up every color seen on a display device.

Ribbon Speaker
A loudspeaker that consists of a thin, corrugated, metallic ribbon suspended in a magnetic field. The ribbon acts electrically like a low-impedance voice coil and mechanically as a diaphragm.

RMS
Root Mean Square or the square root of the arithmetic mean (average) of the square's set of values. A reasonably accurate method of describing an amplifier's power output.

RPTV
Rear-Projection Television

SACD
Super Audio CD. Enhanced audio format with up to six channels of high-resolution audio encoded using DSD. Requires an SACD player. Multichannel also requires a controller with six-channel analog or proprietary digital inputs for full playback.

Sampling Frequency
How often a digital sample is taken of an analog wave. The more samples taken, the more accurate the recording will be. You need to sample at a minimum of twice the highest frequency you want to capture. For example, the 44.1-kilohertz sampling rate of a CD cannot record sounds higher than 22.05 kilohertz.

Scan Lines
The lines drawn by an electron gun in a CRT system to make up the picture. Drawn horizontally, from left to right, starting at the top left and working to the bottom right.

SDTV
Standard Definition Television. Lower resolution subset of the ATSC's DTV system. 480i is typically accepted as an SD signal. Digital broadcasters can offer multiple sub-programs at SDTV quality, as opposed to one or two HD programs. Digital satellite and digital cable often refer to the majority of their programs as SDTV, somewhat erroneously, as ...

Sealed
See Acoustic Suspension.

Sensitivity
A measurement (in dB) of the sound-pressure level over a specified frequency range created by a speaker driven by 1 watt (2.83V at 8 ohms) of power with a microphone placed 1 meter away.

Signal-to-Noise Ratio
A comparison of the signal level relative to the noise level. Larger numbers are better.

Soft-Dome Tweeter
A tweeter that uses a soft fabric or plastic dome as the radiating diaphragm.

Soundfield
The total acoustical characteristics of a space, such as ambience; number, timing, and relative level of reflections; ratio of direct to reflected sound; RT-60 time; etc.

Soundstage
The area between two speakers that appears to the listener to be occupied by sonic images. Like a real stage, a soundstage should have width, depth, and height.

Source
A component from which the system's signals originate. DVD player, AM/FM tuners, and VCRs are sources.

Speaker
A component that converts electrical energy into acoustical energy.

Spider
Part of a loudspeaker driver's suspension that helps center the diaphragm and returns it to rest after being moved by an energized voice coil.