Glossary of Audio, Video and Home Theater
Advanced Audio Coding. An audio codec used increasingly for downloaded music files, streaming-media, and satellite-radio applications.
Analog Analog Digital. A designation that indicates the recorded material was first recorded with analog equipment, then remixed on analog equipment and finally placed onto a digital recording medium.
The original named used for Dolby Digital. The name was later changed to feature the Dolby name.
When audio or video signals pass through a component, the signal may be changed slightly. The closer the output is to the original input, the greater the accuracy of the component.
Acoustic Suspension Speaker
A sealed-box speaker that uses the air behind the woofer to control cone movement.
A speaker which includes an integral power amplifier to power or drive the speaker.
Active Scan Lines
The scan lines in a video frame that carry picture information rather than data for closed captioning or synchronization.
Analog to Digital. Refers to the conversion of analog sound or video to digital during storage, manipulation, or recording.
Analog Digital Digital. A designation that indicates the recorded material was first recorded with analog equipment, then remixed on digital equipment and finally placed onto a digital recording medium.
Adjacent Channel Selectivity
When tuning an FM station, the next station up or down the dial may interfere with the signal. A tuner’s ability to reject those neighboring signals is measured by its selectivity.
Alternate Lighting of Surfaces. An HD plasma panel technology designed to optimize performance when displaying 1080i material. Alternate rows of pixels are lit, similar to interlaced scanning. The resulting picture is bright, clear and improves the smoothness of movement as well extending the life of the plasma panel.
Amplitude Modulation. The encoding of a signal into a radio wave by modulating its amplitude (the height of the wave). As opposed to FM, frequency modulation, wherein the frequency of the wave is modulated.
An audio component that takes line level audio inputs and increases the gain or level and outputs the signal to speakers. Amplifiers are used with other separate components or can be integrated together to make an Integrated Amplifier. Amplifiers are also available for other signals besides audio.
When a signal is continuously variable, it is analog. When a signal is broken into units that are rounded to discrete values, it is digital. Analog signals contain “all of the data” but it is prone to interference and degradation. It is not possible to catch and remove all of the interference from an analog signal and so the quality declines as it travels to your TV. With a digital signal, certain values are expected. When a value is received that is not within the expected range, it can be filtered or adjusted. This ability to detect and filter or repair a digital signal makes it possible to deliver a signal to your TV that is as good as when it left the studio.
It is the preferred DVD format for widescreen (16:9) TVs because the image is restored to its widescreen format without any reduction in image quality. Anamorphic DVDs contain the highest level of resolution (460 to 480 lines) and thus yield the best picture quality. DVDs are often not labeled as anamorphic, so look also for the words “enhanced”, ” widescreen”, “16:9”. DVDs labeled “letterboxed” and in most cases “fullscreen” will have reduced image quality or even have some of the image edited to force it to fit a 4:3 screen. Anamorphic DVDs can be played on regular 4:3 TVs, but unless your TV or DVD player has a setting to vertically adjust the image, it will appear tall and thin.
A standard for measuring the brightness of a projection TV. ANSI is the organization that set the standards for measurement. The IEC is now the organization setting the standard, but manufacturers are reluctant to switch, fearing consumer confusion.
A device for transmitting or receiving signals. The size and shape of antennas are determined primarily by the frequency of the signal they are designed to receive. A high gain antenna is highly focused, whereas a low gain antenna receives or transmits over a wide angle.
Any imperfection in a video image resulting from digital processing such as interlacing, up or down-conversion of the signal or conversion from a native to non-native format and vice-versa.
Essentially the shape of the screen or image. It is the ratio of the width to the height. The standard square television screen is 4:3 or 1.33:1, while widescreen TV is 16:9 or 1.78:1. Most modern films are released in 1.85:1 or 2.35:1 aspects, which means that even on a widescreen TV the image will result in black bars at the top and bottom of the screen.
Advanced Television Systems Committee. The organization that set the U.S. HDTV standards. It also refers to the TV channel tuner used to tune in HD signals. Compare to the NTSC which set the standard for pre HDTV signal and the tuner that tunes analog programming.
To decrease or otherwise reduce, as in to attenuate signal noise.
Advanced Television. The system and the standards defined by the ATSC.
A feature that automatically reverses a tape when it reaches the end.
A feature that automatically rewinds a tape to its beginning when it reaches the end.
Also called a Home Theater Receiver, sometimes the term “integrated” is also used. Receivers take audio signals from components such as a CD player, tape deck and phonograph, amplify it and output it to the speakers. An A/V receiver is designed to also accept video inputs, such as from a DVD player, cable box and VCR, and output the signal to a television. In most cases the video signal is not processed but simply passed through to the TV. A/V receivers, in most cases, also have Dolby and DTS decoders to play multi-channel audio.
The connections on any component, such as a TV, receiver or VCR that enable connection to other output devices. The inputs often take the form of RCA jacks.
An audio output is a connection (most often an RCA jack) on a device, such as a TV, that can be connected to a stereo or home theater system. A fixed output means the stereo is used to control the volume. A variable output means that the TV and the stereo can each control the volume.
Its basic meaning is the width of a specified frequency spectrum. As it applies to sound, the human ear hears sound in the range of 20Hz to 20,000Hz (20KHz). The term is also used synonymously with bit rate and refers to the number of bits per second. It relates to data transfer and refers to the quantity of data that can be transferred.
Low frequency sound; typically frequencies below 185Hz.
Bidirection predictive frame. A video compression method used in MPEG encoding which creates an in-between frame by calculating only the differences from the frame before and the frame after it.
A binary digit that indicates 0 for “off” and 1 for “on.”
The rate at which data passes or is processed. Measured commonly as bits per second (bps) or millions of bits per second (Mbps).
Bitstream data is a digital audio signal decoded by Dolby and DTS decoders. DVD players often label the output jack with PCM (pulse code modulation) for the digital signal output by CDs.
A measurement of a television’s ability to display deep black. The ability to display detail in shadowy or dark parts of the picture is also a factor of a TV’s black level capabilities. CRTs generally have the best black level performance.
DVD format that supports high-definition 1080 lines compared to standard DVD of 480p. It was the leading competitor to HD-DVD in the battle to establish a new DVD standard, until Toshiba finally threw in the towel, leaving Blu-Ray the winner.
To increase, as in to boost a signal.
Combining two channels of an amplifier to make one channel that is more powerful.
Video display brightness refers to underlying light level applied to the image displayed on the screen. Similar to a dimmer on a light bulb, the light level is increased or decreased when adjusting the brightness control. Increasing the brightness to its highest levels is common for TVs on display for sale, although this is not the optimal viewing level because it tends to wash out darker parts of the scene. Brightness is best used in conjunction with contrast or white balance to display the optimal image.
When a stationary image, such as a station logo, stock ticker or video game is left on for an extended period of time, it can become burned into the screen. It appears as a ghostly image, present at all times on any program displayed. Burn-in is most common on CRT and plasma displays. The risk of burn-in can be reduced by avoiding long periods of displaying a static image and by properly adjusting the contrast and brightness settings.
Component video is comprised by three signals. One signal is luminance which is signified by “Y”. The second signal is blue, represented by “B” and finally red, represented by “R”. To extract the proper signal, luminance is subtracted from the blue signal, thus “B – Y”. Depending upon equipment and cables, this may also be labeled as “Cb” or “Pb”.
As it relates to video, calibration refers to adjusting the video display to adhere to a standard. As it relates to audio, calibration refers to adjusting the sound level of each channel to match the level of all other channels.
Component video is comprised by three signals. One signal is luminance which is signified by “Y”. The second signal is blue, represented by “B” and finally red, represented by “R”. “P” describes an analog signal while “C” indicates a digital signal. Depending upon equipment and cables, the signals may alternatively be labeled as “B – Y ” or “Pb” and “R – Y” or “Pr” respectively.
A range of the RF spectrum used by networks and cable companies to distribute programming via geo-stationary satellites. Consumers can also receive these signals using large (8 feet) satellite dish antennas.
Compact Disk. A storage medium for audio, video or data. It can hold roughly 700 megabytes of data.
Compact Disk – Recordable. A storage medium for audio, video or data. It can hold roughly 700 megabytes of data. Identical in appearance to a CD with the added feature that it can be recorded upon one time with the use of compatible recording equipment. The term is also used to refer to the recording equipment. Some but not all equipment that can play a CD can read and play a CD-R.
Compact Disk – Rewritable. A storage medium for audio, video or data. It can hold roughly 700 megabytes of data. Identical in appearance to a CD with the added feature that it can be recorded upon repeatedly with the use of compatible recording equipment. The term is also used to refer to the recording equipment. Some but not all equipment that can play a CD can read and play a CD-RW.
Custom Electronic Design and Installation Association.
Consumer Electronics Manufacturers Association.
In a surround sound system, one channel is designated for primarily carrying dialogue and sounds that would occur directly in front of the viewer. A surround sound speaker is typically placed immediately above or below the screen.
In a surround sound system, the soundtrack of a film is divided to different speakers to deliver the sounds to approximate their source location in the film.
A feature on some televisions that allows a channel to be blocked from regular viewing until the channel is specifically unlocked.
In audio, a measurement of the amount of leakage between channels, specified in dB.
The content on a DVD is usually indexed into chapters for quick selection and access enabling the viewer to skip to a particular chapter on the disk.
The color portion of a video signal. The chrominance channel carries the color signal that when combined with the luminance channel, creates the complete picture. S-video is comprised by the chrominance “C” and the luminance “Y” signals and is represented as “Y C”.
Coax or Coaxial Cable
A round cable commonly used for bringing signals from an antenna or cable provider into a home. This 75-ohm cable is used for longer runs because of its low relative signal loss. However, the use of coax should be limited to those purposes because of it is inferior to other signal carrying wires. RG6, RG11 and RG59 are common varieties of coaxial cable.
enCOder/DECoder. A process for encoding a signal for transmission and then decoding it for playback. Dolby Surround and ProLogic are an example of a Codec.
Light comes in various colors and it is measured in temperature, specifically, degrees Kelvin. A TV starts with a white base and adds color to the white base to make the picture. How the base “white” is set will affect how all other colors appear. The higher temperature, the bluer it will appear. 6500K is the standard temperature for white used for most TVs.
Built into many TVs, this device removes residual chrominance and luminance. Comb filtering enhances detail, outlines and color. However, they are not needed or used when then signal arrives by S-Video, component video, DVI or HDMI cable because they deliver a signal that requires no filtering.
An analog video signal carried on three wires. A separate signal is carried for luminance, blue and red (green is derived). Component video may be referred to as “Y, B-Y, R-Y”, “Y Pb Pr” or “Y Cb Cr”, the terms are used interchangeably. A component video signal is carried on component video cables, which provides a very high quality signal; a step above S-video. This is the minimum quality connection to enjoy the benefits of an HD TV signal or DVD progressive scan. At present, no digital component video consumer products exists, regardless of labels all signals are analog.
a video signal in which the luminance and chrominance information are both carried in a single wire. While better than an RF signal, this cable should be used only if no better connection is available.
The difference between the brightest whites and darkest blacks a TV can display. High contrast ratios are important for a TV to be able display subtle color variations and to overcome ambient light.
The alignment of three electron beams in a CRT based television to converge on one point. When a one red, one green and one blue beam converge, they create white light. The failure of these beams to converge precisely will result in color haloing of images on screen.
Cathode Ray Tube. A large glass vacuum tube in which a beam of electrons is fired at the phosphor coated screen. The energy causes the phosphors to glow, giving off light. A single tube is used in regular TVs while some rear projection and a few video projectors use three CRTs, one for each color channel.
Digital to Analog Converter. Electronic circuit built into various devices to convert digital data to analog for amplification or display by other devices.
Decibel. A measurement of the loudness of a sound; technically, the sound pressure level. The decibel scale is logarithmic and so a 10 dB represents a doubling of the sound level; so 60dB is twice as loud as 50dB.
Digital Digital Digital. A designation that indicates the recorded material was first recorded with digital equipment, then remixed on digital equipment and finally placed onto a digital recording medium..
A device, or circuit in a device, which converts interlaced video to progressive scan video. Interlaced pictures are painted in two passes. Every other line is painted in the first pass and the alternate lines are painted on the second pass. A deinterlacer, aka line doubler, creates a complete picture, filling in all of the lines, for each scan. More lines results in a better picture.
Digital Cables Ready (DCR)
A TV or product that is equipped with a CableCard slot and thus enabled to receive encrypted cable signals without the need for a set-top box (STB).
A television based upon direct view CRT technology. While rear projection CRT TVs use CRTs, they are not viewed directly but rather are reflected.
Digital light processing. A rear projection television based upon technology that uses a chip with hundreds of thousands of microscopic moving mirrors. Each mirror corresponds to a single pixel on the screen. Light is reflected through an RGB color wheel to create the required colors. More expensive models use three separate mirror devices, one for each color, instead of using a color wheel.
Dolby laboratories developed surround sound which distributes audio signals to speakers placed around the room to create an effect of directional and ambient sound. There are several Dolby products the most well known of which are ProLogic and Dolby Digital.
The conversion of a higher resolution television signal to a lower one. For example, some networks broadcast HDTV at 1080i, while many plasma screens display 752 lines. Therefore, the signal must be downconverted to be displayed on the screen. Because of the many different resolutions used in home theater, downconversion and upconversion processes are frequently required. The quality of the process varies by manufacturer and viewer preference.
Digital Signal Processing. An electronic circuit for the enhancement of signals after conversion from analog.
Digital Satellite System. A subscriber satellite broadcast service similar to cable television. Network and premium television signals are beamed from geosynchronous satellites to personal receiver dish antennas.
Digital Theater Systems. A surround sound technology directly competing with the Dolby surround standards. Products include DTS-ES and DTS:NEO6.
Digital Television. The generic overall term for the digital video broadcast (ATSC) adopted to replace the old analog standard (NTSC). It consists of 18 different formats, all of which must be supported by new digital ready televisions. For more information, see our article on HD TV.
D-VCR or D-VHS
Digital VCR. Similar to standard VHS VCRs except that they have the capability to record and playback HDTV.
Digital Versatile (or Video) Disc. A 5-inch diameter optical disc used for the recording of movies, music, software and data. The term is also sometimes used to refer to the DVD player.
Digital Visual Interface. A digital video signal connectivity standard that uses an uncompressed digital signal. DVI does not carry an audio signal, while the similar HDMI standard does. DVI signals are used in both home theater and computing. The DVI-I connector carries digital or analog while the DVI-D carries digital only. The two are compatible although an adapter may be needed to connect one to the other.
Digital Video Recorder. aka PVR or Personal Video Recorder. Similar to a VCR although with much greater capabilities. A DVR records to an internal hard disk drive. It can record and play back a different recording simultaneously. With it you can pause live television and in some cases record more than one show simultaneously. It allows for easy set-up to record a program one time or on an ongoing basis. While once a subscription product available from a small number of companies like Tivo or Replay, many cable companies and satellite systems are now offering the service.
Enhanced Definition Television. A display capable of displaying 480 lines progressively (480p). If presented with a higher resolution signal (HD signal), the signal will be downconverted to fit the native resolution of the EDTV. DVDs output 480p (when connected with component cables or better) a perfect match for EDTVs.
Electronic program guide. A feature found on most DVRs, cable and satellite set-top boxes. It provides an on-screen listing of available programming by channel and time.
When data or a signal is transmitted, pieces can become lost or damaged. Error correction technology replaces these pieces by guessing, estimating or calculating what was lost.
A screw-on connector type used with coaxial cable.
A cable containing a glass fiber for the transmission of light impulses. The light impulses carry a signal which is nearly impervious to interference and resistant to signal loss.
Frequency Modulation. The method of encoding a signal into a carrier wave by modulating the frequency of the waves.
A television projector that projects the image onto a separate screen or wall. Front projectors may use CRT, LCD or DLP technology.
Frames per second. The number of individual still pictures (frames) that are viewed or processed in one second. Film runs at 24fps, while video, runs at 30fps.
The Measurement of the reflectivity of a surface, such as a projection screen. The higher the number the greater the amount of reflected light and thus the brighter the image.
To restore a displayed image to the appearance of the original, gamma correction must be applied. When an image is filmed and then replayed, there is a difference from the original. Some parts of the image are more different than others. The relationship between any point of the display and the original can be displayed on a graph. This relationship is the gamma.
The bending of straight lines and distortions, especially at the corners of the screen.
The range of gray gradations from pure white to pure black.
High-bandwidth Digital Content Protection. This copy protection scheme was developed to prevent unauthorized copying of copyrighted material such as music and films. It is used only with digital transmissions, currently DVI and HDMI. A digital source and digital display must both be HDCP enabled for the transmission to take place.
High-Definition Multimedia Interface. High bandwidth connection allowing uncompressed transmission of digital video and audio. Successor to DVI; compatible with DVI with the use of an adapter.
High-definition television. A subset of the DTV standard called ATSC. The new broadcasting standard replaces the old NTSC analog standard. The HDTV signal is digital, supports vertical resolution up to 1080 lines and a widescreen aspect ratio of 16:9.
A channel tuner to tune in high-definition television broadcasts. Also called an ATSC tuner.
Hertz is a measurement of frequency. It measures the number of cycles of a wave per second. As it applies to sound frequency 1 hertz is a very deep sound and 20,000 hertz is very high pitched sound.
The number of dots across the screen varies depending upon the source. Examples of common sources and their horizontal resolution include VHS VCRs – 240 lines, analog TV broadcasts – 330 lines, DVDs – 540 lines and DTV signals range from 640 lines for SDTV to 1,280 lines for 720p HDTV and 1,920 lines for 1080i HDTV.
see Hertz above.
Also called Firewire or IEEE 1384. A high-speed data transfer technology. It is often used with video and digital cameras to transfer data.
In a direct current (DC) circuit it is synonymous with resistance. In an alternating current (AC) circuit, it is the interaction of inductive and capacitive forces as well as resistance.
The part of the electromagnetic spectrum just below the frequency range of visible light. Most remote controls use infrared light for signaling.
Typically a tuner, preamp and power amplifier combined into one unit. Sometimes called a receiver. If it includes video inputs and/or surround sound decoders, it is also referred to aHome Theater Receiver.
Generic term for any cable or connector used to connect audio and video equipment.
The process of painting the image onto the TV screen in two passes. On the first pass the even number horizontal lines are painted. On the second pass, the odd number lines are painted. This happens fast enough that your mind blurs the two passes into one image. Compare to progressive scan in which the entire image is created, line by line, in one single scan.
A female connector, as opposed to a plug which is a male connector.
A dried meat product made from thin dried (or cured) strips of meat. It can be eaten while watching your home theater. Sorry, we were short on “J” words.
A feature found on some VCRs that allows to the viewer to use a rotary dial to scan forward and backward to more easily find a particular passage.
An error that results in a DVD player skipping ahead.
Kbps or Kb/s
Kilobits per second. A rate of data flow or processing. 1,000 bits per second is annotated as 1 Kbps.
When an image from a video projector is projected onto a surface, the image is sometimes distorted. The distortion results from the projector being off-center and out of square with the screen. This distortion is called keystoning. Many projectors have a feature that allow an adjustment to be made to restore the image to its proper shape. Optical keystone correction adjusts the image proportions by physically modifying the light-path through the lens system. This method results in no loss of resolution. Digital keystone correction adjusts the image proportions by shrinking the image’s furthest edge before the image is generated by the projector. This method results in a loss of resolution and may also introduce artifacts.
kilohertz or 1,000 hertz. Hertz is a measurement of frequency. It measures the number of cycles of a wave per second. As it applies to sound frequency 1 hertz is a very deep sound and 20,000 hertz is very high pitched sound.
A range of the RF spectrum used by networks and cable companies to distribute programming via geo-stationary satellites. Consumers can also receive these signals using large (8 feet) satellite dish antennas.
A DVD contains up to two data layers on each side. Each data layer can hold about two hours of NTSC video. Movies longer than two hours long or encoded at a high data rate, are spread across the two layers on one side of the DVD. The laser is refocused to play the second layer and when the player changes to the second layer, the video and audio may freeze momentarily.
Liquid Crystal Display. A panel consisting of two transparent polarizing panels with a liquid crystal material sandwiched between. When voltage is applied, individual crystals turn dark. Behind the panels is a light source which flows through clear crystals and is blocked by dark crystals. The pattern of off and on crystals creates the image.
A form of universal remote that can control all the devices in a home theater from a single contoller. A universal remote control can be programmed with control codes for broad range of devices. A learning remote adds to this ability by being able to “talk” with the original remote. By placing an original remote head-to-head with a learning remote, the signal from the original remote is learned and assigned to a button on the new remote.
Light Emitting Diode. Used as an indicator light in many devices for many years, it is now also being employed as the light source in LCD (LED) televisions. LCD TVs have typically used fluorescent backlighting, but LED backlights have many advantages and may ultimately replace fluorescent backlights.
Because some images, such as wide-screen movies, do not fill a TV screen, black bars are placed above and below the image to fill the unused space. This allows to movie to be shown in its native aspect rather than being adjusted to fit the screen. When bars are placed to the left and right sides of an image it is called windowbox.
Low Frequency Effects or the bass audio signal. Generally the signal between 20-150Hz that is played through a subwoofer.
A device, or circuit in a device, which converts interlaced video to progressive scan video. Interlaced pictures are painted in two passes. Every other line is painted in the first pass and the alternate lines are painted on the second pass. A line doubler, aka deinterlacer, creates a complete picture, filling in all of the lines, for each scan. More lines results in a better picture.
A compression algorithm that doesn’t lose any of the original data. The original image or sound is completely preserved.
A compression algorithm that removes some data, to reduce the file size, while preserving the sound or image. Data that is removed is lost, thus altering the original image permanently.
A feature on many receivers that attempts to compensate for the loss in low-frequency sound at lower volume levels.
The brightness portion of a video signal, represented as “Y”. The luminance signal carries the picture detail information and can produce a complete black and white image.
Copy protection scheme used to protect DVDs and videotapes from illegal duplication.
A method of combining audio signals into fewer channels for the purpose of compression. When the matrixed signal reaches the processor, it is decoded and restored or enhanced into multichannel sound, such as surround sound.
Mbps or mb/s
Megabits per second. A measure of the volume of data transmission or processing.
Megahertz. 1 MHz is equal to one million hertz (Hz) or one thousand kilohertz (kHz). A measurement of signal bandwidth or processing speed.
A circular pattern that appears in video when straight lines appear close together. The lines tend to converge and split apart as they are drawn. The effect has to do with the nature of the television display and the relationship of the position of the rendered line and the scan line.
Monaural or Mono
Monophonic sound. A method of recording or reproducing sound in which all sound is blended into a single channel.
The term is most accurately applied to video or television monitor that has no tuner. In such a case, a monitor must have some source device connected to it in order to display anything. The is sometimes applied, less accurately, to a television that has inputs for devices such as VCR or DVD player.
A compressed audio format commonly used for music downloaded from the internet or for music stored on memory-based audio players.
Motion Picture Association of America. The organization responsible for assigning film ratings. G = General audience; PG = Parental guidance suggested; PG-13 = Parents strongly cautioned; R = Restricted, accompanying adult required; NC-17 = No one 17 and under admitted; X = No one 17 and under admitted.
Motion Picture Experts Group technical standard 2. A video compression standard used in digital broadcasts and other digital media such as DVDs. It reduces the amount of data transmission by not having to retransmit data identified as not having changed from the previous frame.
Multi-channel TV Sound. The stereo audio signal broadcast with television transmissions.
Televisions have a fixed set of pixels or scan lines. That is their native resolution. However, the programming displayed on the set may have its own native format which differs from that of the television. When this happens the program has to be converted to fit the native format of the television.
Refers to any of a variety of systems used to reduce background noise in analog audio signals. Dolby and dbx are two of the most well known noise reduction systems.
National Television System Committee. U.S. government created organization which over 60 years ago defined the analog standard for broadcast television. The term is also used to refer to the standard itself and to devices that use the NTSC standard. The standard calls for 525 scan lines of which 480 are used for picture display. The NTSC is used primarily in North America and Japan.
An enhancement for DVD players that promises additional control, features and uses for this component. The addition of a processor may enable the DVD player to take on a new role in your multimedia system. NUON was created by VM Labs.
Original Aspect Ratio. The aspect ratio in which the source material was originally produced.
The measure of resistance to the flow of electricity.
A digital audio jack to connect, most commonly, a DVD player to a Home Theater Receiver. Also called Toslink.
Over the air. Television signals that arrive through the air and are picked up by an aerial antenna are called OTA signals.
Television manufacturers enlarge the picture so that it goes outside the boundaries of the viewable screen. As much as 20% of the picture may be lost due to overscan. The reason manufacturers deliberately waste some of the picture is to hide distortion and other imperfections in the edge of the image. On some RPTVs the amount of horizontal or vertical overscan can be adjusted.
Phase Alternate Line. The most widely used analog broadcast standard worldwide. Like NTSC (used in North America & Japan) it is an interlaced signal, although it differs in that it has 625 lines of resolution and 50 cycles per second. Equipment that uses one standard cannot play the other standard. There is a third standard, SECAM, used in France; PAL programming can be played on SECAM equipment, but only in black and white.
Component video is comprised by three signals. One signal is luminance which is signified by “Y”. The second signal is blue, represented by “B” and finally red, represented by “R”. “P” describes an analog signal while “C” indicates a digital signal. Depending upon equipment and cables, the signals may alternatively be labeled as “B – Y ” or “Cb” and “R – Y” or “Cr” respectively.
Pulse Code Modulation. A method of encoding an audio signal into a digital format. PCM is the method used to encode audio data onto CD.
Black bars on all four sides of the image. This occurs when a station broadcasts an upconverted 4:3 aspect ratio program within a 16:9 frame.
One program (channel) is displayed on the full TV screen at the same time as one or more other programs are displayed in inset windows.
Pixel response time
The time it takes for a pixel to switch from active to inactive. Slow response time, more than 16 milliseconds, results in motion trails following fast moving objects on screen.
A technology used for the creation of one of the two types of thin panel displays. Plasma displays have two glass panels with roughly one million pixels sandwiched between. Each pixel has three cells, one red, one green and one blue. Each cell is filled with a gas and when current is applied the gas emits UV rays which stimulate the phosphors to glow. The process is similar to the way a fluorescent light glows.
A male connector, as opposed to a jack which is a female connector
Picture LineUp Generation Equipment. The name of a test pattern used in adjusting the picture black level.
An opening in a loudspeaker enclosure designed to improve sound quality.
The term often applied to the control section of a receiver or integrated amplifier. The control section “pre” processes input signals before sending them to the power amplifier.
On an AM or FM tuner, memory settings to recall preselected radio station frequencies.
The components of a video signal are represented by specific symbols, such as “Y” for luminance. If the signal has gamma compensation applied then a “prime” symbol is added to denote modified signal. In the case of a gamma compensated signal, it would be denoted as Y’.
In order to keep references simple, the gamma compensation may be ignored and the apostrophe is omitted.
An image that is painted line by line in a continuous fashion. Compare to interlace scan which paints every other line, requiring two scans to create a complete image.
A television thats projects an image onto a screen rather drawing it directly on a phosphor coated screen (CRT). Projection TVs can be front projection (onto a separate screen or wall up to 20 feet away) or rear projection (onto a screen built into the television housing).
Quadrature Amplitude Modulation. AM Radio uses amplitude modulation to encode a signal onto a carrier wave. In a similar fashion, signal is encoded on two AM waves that are out of phase; while one wave has a peak, the other has a valley. This method of encoding is common in cable and satellite transmissions.
A visual artifact associated with single-chip DLP based televisions. It results from the use of a color wheel to project colors in a sequential rather than continuous manner. Not all viewers can see the effect and even fewer are bothered by it.
Cable withRCA connectors are often called RCA cables. However, composite would be the more correct term, because that is what is usually being referred to when this term is used; and there are other cables that use RCA connectors.
Region Code Enhancement.
Instead of an arbitrary counter, a counter that indicates the actual number of hours, minutes and seconds played or remaining on a VCR, DVD or DVR.
In home audio, an integrated amplifier which includes an AM/FM tuner. Receivers take audio signals from components such as a CD player, tape deck and phonograph, amplify it and output it to the speakers. An A/V receiver is designed to also accept video inputs, such as from a DVD player, cable box and VCR, and output the signal to a television. In most cases the video signal is not processed but simply passed through to the TV. A/V receivers, in most cases, also have Dolby and DTS decoders to play multi-channel audio.
A method by which DVD playback is restricted by geographic region. The DVD regions are defined as: Region 1 (United States of America, Canada); Region 2 (Europe, including France, Greece, Turkey, Egypt, Arabia, South Africa); Region 3 (Korea, Thailand, Vietnam, Borneo, Indonesia); Region 4 (Australia, New Zealand, Mexico, Caribbean, South America); Region 5 (India, Africa, Russia and former USSR countries); and Region 6 (Peoples Republic of China).
The measurement of a display device’s capability to display discrete details, such as pixels or lines. For instance many LCD televisions have a vertical resolution of 720 pixels and a horizontal resolution of 1280 pixels.
RF Input, jack or connector
Radio Frequency Input. Refers to the coaxial cable input on a TV, VCR, satellite or cable box for the signal from the antenna or cable provider.
Radio Frequency Interference.
A video signal comprised by the three colors red, green and blue and carried on three separate wires.
Root Mean Square. The square root of the sum of the squares of a set of values divided by the total number of values. A common measurement of average power output in audio amplifiers.
Rear Projection Television. RPTVs include CRT, LCD, LCoS an DLP technologies. In each case the image is formed by reflecting it onto the screen from the rear. CRT based RPTVs have been around the longest and are physically the largest. The other technologies have enabled the creation of the smaller “microdisplay”, which can be placed on a tabletop.
Component video is comprised by three signals. One signal is luminance which is signified by “Y”. The second signal is blue, represented by “B” and finally red, represented by “R”. To extract the proper signal, luminance is subtracted from the red signal, thus “R – Y”. Depending upon equipment and cables, this may also be labeled as “Cr” or “Pr”.
Super Audio Compact Disc. A high-resolution audio CD format. SACD and DVD-A (DVD-Audio) are the two formats competing to replace the standard audio CD. Both SACD and DVD-A offer 5.1 channel surround sound in addition to 2-channel stereo. Both formats require special players although both will play in stereo on a standard player.
Second Audio Program. A second audio channel, used to carry an alternate sound signal such as a soundtrack in a second language on a TV broadcast channel.
Standard Definition Television. SDTV is frequently used, incorrectly, to describe old analog NTSC broadcast television. SDTV is the digital broadcast television standard defined under the DTS standards developed by the ATSC. An SDTV is defined as being able to receive an ATSC signal and in most cases will have 480 lines of resolution.
Sequential Couleur Avec Memoire. The analog broadcast standard used in France, Russia and Greece. It uses 625 scan lines, of which 575 are actually displayed and uses a refresh rate of 50Hz. Compare to NTSC and PAL.
A control on televisions that creates the effect of greater resolution by accentuating light to dark transitions. Setting the sharpness too high actually degrades the picture by exaggerating the transitions.
also S/N. Measured in decibels, this is the difference between the signal strength a system reproduces compared to the strength or amplitude of its background noise.
Electronic circuits comprised of transistors and integrated circuits, rather than vacuum tubes.
Refers to the signal source material or player. For example, source can refer to a DVD player, the DVD being played or the signal output from the player. Sources include, but are not limited to, television broadcasts, DVDs, video tapes and CDs.
Surround sound routes sound to individual speakers, which when placed around the room, makes the sound seem to come from the proper position relative to the film. As a plane flies from on screen, over your head and into the distance behind you, the sound follows the movement of the plane from the front speakers to the rear speakers.
Device used to transfer movie film onto electronic media. The flying spot scanner is the most common variety of telecine. It has a single pixel scanner that scans over an illuminated film frame to record the proper number of pixels for the format being transferred to.
Total harmonic distortion. Audio signals become distortion as they pass through electronic circuits. The amount of distortion is expressed as a percentage. Lower numbers are better, but in general the human ear cannot detect distortion less than 2%.
Video Projectors typically are rated for minimum and maximum throw distance. The minimum distance is the closest the projector can be placed to the screen while maintaining proper focus. The maximum distance is typically a recommended distance based upon image brightness.
For video projectors this ratio is the throw distance divided by the width of the projected image. A fixed throw projector can only change the image size by moving the projector closer or farther from the screen. Video projectors with a zoom feature can adjust the image size by zooming in or out, while leaving the projector itself unmoved.
A playback standard developed by Lucasfilm. It is not a recording technology as many mistakenly believe. It is a rigorous set of standards for equipment used in the playback at theaters and more recently in homes.
Recording a program for viewing at another time.
Controls for the adjustment, most often, of treble and bass.
A a squarish connector for a fiber optic cable used for DVD optical audio output. Often the entire cable is referred to as a Toslink cable. It is also called an optical cable.
The higher frequency audio signal range, approximately 3,000 Hz and higher.
Refers to a CRT television, because it uses a cathode ray “tube”.
Audio: A device for tuning AM and FM radio signals. Video: A device for tuning television broadcasts. Typically the are built into another unit (such as a A/V Receiver or TV respectively), although they can be sold as separate components.
A physically small speaker driver designed to reproduce higher frequencies 3,500 Hz and over.
A wire containing two wires widely separated in a thin flat wire use for connecting to aerial antennas. Sometimes called 300 Ohm.
A loudspeaker that has two drivers; one each for high frequencies and bass. The midrange frequencies are divided between the two drivers. Generally, two way speakers don’t perform as well as three way speakers.
Ultra High Frequency. Radio waves that carry the higher numbered television channels. VHF carries the lowered number channels.
When the television picture is not adjusted to fill the entire screen resulting in black bars around the image. This is not the same as a piller box which results from the source material not filling the screen.
Universal Remote Control
A remote control that is able to control several different audio and video components. The manufacturer provides a list of codes that the user must program into the remote for their own specific brands and models of equipment.
When the source material is changed to from a lower resolution to a higher one. The signal is upconverted to have more pixels or scan lines.
Uninterruptible Power Supply. A battery backup power source, commonly used with PCs. However, because some AV components require internal cooling fans after shut down, a UPS will prevent overheating in the event of a power outage. Most UPSs also have power filtering and surge protection circuits.
Variable Bit Rate
When a DVD is played the rate that data flows is not fixed. Complex, action and other dynamic scenes will result in higher data rates while still images require a lower data rate.
A chip built into televisions that allows certain objectionable content to be blocked. The chip reads ratings transmitted with television programming and blacks them out at the level preset by the TV’s owner.
Videocassette Recorder. A device for the recording of audio and video onto large cassette tapes. VCRs have the ability to record from OTA, cable, satellite, video cameras and other VCRs. While VCRs sales are declining, the industry hopes to revive sales with an HD model capable of recording and playing high-definition programs.
A time-shift control system featured in some VCRs to make recording easier.
Vertical Blanking Interval
The interval of time for the scan to return from the end of one frame back to the beginning of the next frame. This is typically measured in scan lines. The NTSC calls for the VBI to be 40 scan lines.
The number of lines or pixels from the top to the bottom of the screen. The larger the number, the better the resolution and the ability to show fine detail. Analog NTSC televisions can display 480 lines interlaced, DTVs can display from 480 lines progressive up to 1080 interlaced.
Video Home System. The winner of the VHS – Betamax format war for dominance. The standard prescribed the technical requirements for VCR and video tapes.
Very High Frequency. Radio waves that carry the lower numbered television channels. UHF carries the higher numbered channels.
Watts per channel. The output of an audio amplifier is typically rated in watts per channel.
More commonly called contrast. The proper setting for contrast is 12 to 20 foot lumens. If you don’t have a meter handy, then turn the contrast way down and then back up to the point where white appears white. Most TVs are shipped with the contrast set too high.
A picture that has black bars to the left and right of the image. This typically occurs when a 4:3 program is displayed on a widescreen television.
An individual speaker driver designed to handle the low frequency bass range compare to a subwoofer.
A connector used for balanced audio cable, primarily in pro-audio equipment.
Y Cr Cb
While used synonymously with Y Pr Pb, this standard does differ slightly, in part, that it is a digital signal. However, this standard is not commonly used in consumer electronics. Cables and connections marked with Cr Cb or Pr Pb are routinely cross connected. See Y Pr Pb below.
Luminance and Chrominance video signals. This two signals are carried by an S-video connection to create a complete image.
Y Pr Pb
Luminance, Analog Red and Analog Blue video signals. The three signals carried in an analog component video signal. The green signal is derived mathematically. These three components are required for an HD-signal.
Y Pr Pb H V
Similar to Y Pr Pb but with two additional cables, one for horizontal sync and one for veritcal sync. Commonly used for computer monitors.
The distance range for the placement of a video projector. The greater the distance from the screen, the larger the image. However, not all projectors yield the same image size at the same distance, so selection of a projector should be based upon the manufacturer’s statement of the image vs: distance ratio.