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Home Theater Glossary
- Definition Of Home Cinema Terms

The home cinema glossary is your friend. Don't be afraid of the geek speak! Use the jargon buster and put yourself in control!

| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |

| A | B | C | D | E | F | G | H | I | J | K | L | M |

| N | O | P | Q | R | S | T | U | V | W | X | Y | Z |

1

100Hz

A refresh rate used by modern TVs in areas which use the PAL TV system. An interlaced PAL TV signal has a refresh rate of 50Hz. The TV will create a duplicate copy of each field - so the original 50Hz refresh rate will double to 100Hz. The idea is a higher refresh rate will appear to have less motion blur and flicker to the human eye

120Hz

A refresh rate used by modern TVs in areas which use the NTSC TV system. An interlaced NTSC TV signal has a refresh rate of 60Hz. The TV will create a duplicate copy of each field - so the original 60Hz refresh rate will double to 120Hz. The idea is a higher refresh rate will appear to have less motion blur and flicker to the human eye.

1080i

A shorthand description for a type of high-definition picture. Often used to describe the capabilities of flat screen TVs and other digital video equipment. '1080' refers to the number of vertical pixel lines that make up one frame of the picture. The 'i' tells us the picture is interlaced.

1080p

A shorthand description for a type of high-definition picture - also known as full HD. 1080p currently provides the most detailed picture available with high-definition - which is why everyone gets so excited about it! Often used to describe the capabilities of flat screen TVs and Blu-ray players - although it really relates to an image resolution rather than a native resolution. '1080' refers to the number of vertical pixel lines that make up one frame of the picture. The 'p' tells us the image will be displayed using progressive scan. Follow the link for more on the 1080p resolution.

1280 x 720

The native resolution of an HD ready flat panel display, or the minimum image resolution of a high-definition picture. It means the display/image has 1280 vertical lines of pixel information, and 720 lines of horizontal pixel information. In reality, some displays may have a slightly different native resolution (eg. 1366 x 768 or 1024 x 768) due to the size and shape of the pixels that make up the screen.

16:9

The standard aspect ratio of HDTV. Also known as 1.78:1. It means the shape of the picture is 16 units across and 9 units down.

1920 x 1080

The native resolution of a full HD flat panel display, or the image resolution of a full HD picture. It means the display/image has 1080 vertical lines of pixel information, and 1920 lines of horizontal pixel information.

4

4:3

The original standard aspect ratio for television programmes. Also known as 1.33:1. It means the shape of the picture is 4 units across and 3 units down. Becoming less common as transmissions switch to widescreen.

480i

SDTV picture signal in NTSC regions. '480' is the number of visible vertical lines of information in a frame (525 lines in total). 'i' means the signal is interlaced.

480p

Enhanced definition picture signal. '480' is the number of vertical lines of information in a frame. 'p' means the signal is progressive scan.

5

5.1 Surround Sound

See surround sound.

576i

SDTV picture signal in PAL regions. '576' is the number of visible vertical lines of information in a frame (625 lines in total). 'i' means the signal is interlaced.

7

7.1 Surround Sound

See surround sound.

720p

A shorthand description for a type of high-definition picture. This is the minimum requirement for a picture that can be called high-definition. Often used to describe the capabilities of flat screen TVs and Blu-ray players. '720' refers to the number of vertical pixel lines that make up one frame of the picture. The 'p' tells us the image will be displayed using progressive scan.

A

Active Subwoofer

A subwoofer that has a built-in amplifier. This type of subwoofer should receive a pre-amp signal (a signal that hasn't been amplified yet) from an AV receiver. The subwoofer then amplifies the audio signal itself and plays it back through the speaker. Active subwoofers commonly have basic volume and equalisation controls on the unit to alter the output volume and tone. Most subwoofers designed for home cinema will be active subwoofers - and most AV receivers will send a pre-amp signal from the sub output.

Aspect Ratio

The aspect ratio tells us the shape of a TV image. The aspect ratio of an image is its width divided by its height. For example, the traditional shape of a television picture is 4:3. This means it is 4 units across and 3 units down (so not quite square). Four divided by three = 1.33. So the aspect ratio of a 4:3 image is 1.33:1 - or, it is 1.33 times wider than it is long (not quite square!). If you look on the back of a DVD case, it will tell you the aspect ratio of the film on the disc - it may say 4:3 or it may say 1.33:1 (or both!). The aspect ratio of a 16:9 HDTV image is 1.78:1. Find out more about the TV aspect ratio.

AV Amplifier

The same as an AV receiver, except it doesn't have a built-in radio tuner.

AV Receiver

The brain of a modern home cinema system - an amplifier/processor for surround sound systems and a switcher for multiple input devices. An AV receiver is used to easily switch between different input sources (such as satellite TV boxes, games consoles and DVD/Blu-ray players). All input devices are connected to the AV receiver (video and audio connections), which then sends the video signals to the display device (e.g. an LCD TV) - and the audio signals to the speakers. An AV receiver has a built-in radio tuner, which makes it different to an AV amplifier. The receiver will also process a 5.1/7.1 surround sound audio signal and send it out to the connected surround sound speaker system. For more information go to the introduction to the surround sound receiver.

B

Backlit LED TV

A type of LED TV. The LED lights are placed in banks behind the screen. Each bank can be switched on and off independently of each other (sometimes called local dimming), which results in an improved contrast ratio over standard LCD TVs.

Bipole Speakers

Bipole speakers have two sets of speaker drivers, and send the sound from two sides of the speaker cabinet at the same time. They are ideal as surround speakers in a 5.1/7.1 system as they spread the audio better than normal direct radiating speakers and create a less directional sound. Another alternative are dipole speakers.

Blu-ray Disc

A Blu-ray disc is an optical storage disc similar to a DVD. Blu-ray is the same size as a CD/DVD but it cannot be played in a conventional CD or DVD player. The advantage of a Blu-ray disc is that it can hold about six times the amount of data compared to a dual-layer DVD. This means a Blu-ray disc can store video and audio in high resolution formats that wouldn't fit on to a DVD. Therefore, a movie can be watched in 1080p high-definition video and heard with uncompressed multi-channel Dolby TrueHD or DTS-HD Master Audio. You can think of it as high definition DVD if you like. For more information go to the introduction to Blu-ray DVD players.

C

CCFL

Stands for Cold Cathode Fluorescent Lamp. The traditional type of lamp used as the backlight in an LCD TV. In some new LCD TVs, this type of lamp is now being replaced by the use of LEDs (light-emitting diodes) - and these televisions are often referred to as LED TVs.

CEC

Stands for Consumer Electronics Control. A two-way serial bus connection between AV devices that allows them to control each other. This connection is built-in to the HDMI specification and so this control happens over an HDMI interface. Each manufacturer has a different name for this feature such as BRAVIA Sync (Sony) and Viera Link (Panasonic).

Coaxial

A type of cable used for transmitting various radio, video and audio signals. It has a solid conductor core, a plastic insulation layer, another thin conductive layer and finally an outer insulation layer. A 75 ohm coaxial cable is recommended for a digital audio coaxial connection to ensure correct transmission of the signal. A coaxial connection for digital audio will use one RCA connector at each end. Find out more on the coaxial digital audio cable.

Codec

Short for coder-decoder. In terms of home cinema, codec is a term used to describe various digital compression algorithms such as those used for compressing/decompressing audio on DVD and Blu-ray discs. Therefore we can refer to the Dolby Digital codec, or the DTS 5.1 codec.

Component Video

A common output option on DVD, Blu-ray and other audio-visual equipment. You'll see the red, green and blue RCA connectors. Component video is an analog video signal that is split into two or more separate signals. This splitting of the signal creates a better image than composite video. RGB and YPbPr component video splits the signal into three parts, and each uses the same type of cable to connect devices (red, green and blue RCA cable). Find out more about the component video connection and cable.

Composite Video

A common output option on audio-visual equipment. You'll see the single yellow RCA connector. Composite video is an analog video signal and is the most basic type of video signal. The quality is not as good as S-Video or component video. It is called composite video as it combines three signals (YUV) and sends them as one. Therefore, a composite video cable only has one connection to plug in at each end - the yellow RCA. More information on the composite video connection and cable.

Contrast Ratio

The contrast ratio is the difference between the brightest (white) and darkest (black) colour signals that a panel can produce - expressed as a ratio. i.e. a contrast ratio of 500:1 means the darkest black level is 500 times darker than the brightest white level. A higher contrast ratio is theoretically better as it means the whites are whiter and the blacks are blacker - which produces a more realistic and vibrant image. However, don't get too carried away by the ever growing numbers proclaimed by the manufacturers - in real world situations they can often mean very little. Just be aware that this is something to look out for when comparing different TVs. Can your eyes see a difference between the blacks and whites on different screens? Which looks better to you?

CRT TV

The old style of TV. CRT stands for cathode ray tube and this is the technology used to produce a picture on the screen. One problem with using the cathode ray tube to display pictures is they are large, deep and heavy (which is why you used to strain your back when you had to move the TV!) They are being replaced by flat screen technologies that can provide thinner and lighter panels e.g. LCD and plasma.

D

Dipole Speakers

Dipole speakers have a pair of speaker drivers in the same cabinet, and can therefore send the sound in two different directions. They are ideal as surround speakers in a 5.1/7.1 system. The sound in dipole speakers are out of phase (when one side is pushing the other side is pulling), and this creates a very diffuse sound that is difficult to pinpoint. It is important to install this type of speaker in the correct position to get the right effect. Another alternative are bipole speakers, which are more flexible in their positioning.

De-interlacing

The process of converting an interlaced video signal into a progressive scan signal in order to display it on a fixed-pixel HDTV display. Any flat screen display shows images as progressive scan - so any interlaced scan video sources need to be de-interlaced by the TV before they are shown. This process will be done automatically by the TV - although some models will do this better than others.

DLNA

Stands for Digital Living Network Alliance. A trade organisation of over 250 companies who aim to create a set of standards to make it easier to use and share digital music, video and photos. A 'DLNA-certified' device will be able to share data with other DLNA devices on the same network. A standard setup would have a DLNA server which stores the digital media (like a PC or NAS drive), and one or more DLNA clients which will 'see' the server on the network and be able to play back the files (like a TV, laptop or Blu-ray player).

DLP

Short for Digital Light Processing. A video technology developed by Texas Instruments and used in various display systems. This system creates an image by projecting light on to a matrix of small mirrors. Widely used in the manufacture of front projectors - both for the home and in professional cinemas - and sometimes used in rear projection TVs.

Dolby Pro Logic II

An audio signal processing technology developed by Dolby. It creates a 5.1 surround sound mix from a standard 2-channel stereo soundtrack. Pro Logic II is a replacement for the original Pro Logic system, and is found on many devices such as AV receivers and games consoles.

Dolby Pro Logic IIx

Similar to Dolby Pro Logic II, except it will create a 6.1 or 7.1 surround sound mix from either a stereo or 5.1 soundtrack.

Dolby Pro Logic IIz

An improvement on Dolby Pro Logic IIx. This version adds a new height dimension to surround sound. For Dolby Pro Logic IIz you should add two speakers above the usual front left and right speakers to create an even more realistic feel to certain sound effects - especially things like wind and rain. These height speakers can be added to a 5.1 system to create 7.1 (with front height speakers instead of back left and right) - or to a 7.1 system to create a 9.1 system. Obviously the AV receiver will need to support these speaker configurations for this to be available.

Dolby TrueHD

A multi-channel audio format developed by Dolby and used on Blu-ray discs. Dolby TrueHD uses lossless compression - meaning the audio data is compressed to fit on the disc, but what you hear is the uncompressed audio i.e. you hear the audio exactly as it was on the studio master tapes. You get a wide dynamic range, deep bass and a sparkling top end. It's fab! It competes with DTS-HD Master Audio and on a Blu-ray disc you may get either format - or both.

DTS-HD Master Audio

A multi-channel audio format developed by Digital Theater System (DTS) and used on Blu-ray discs. DTS-HD Master Audio uses lossless compression - meaning the audio data is compressed to fit on the disc, but what you hear is the uncompressed audio i.e. you hear the audio exactly as it was on the studio master tapes. You get a wide dynamic range, deep bass and a sparkling top end. It's great! It competes with Dolby TrueHD and on a Blu-ray disc you may get either format - or both.

DTS Neo:6

An audio signal processing technology developed by Digital Theater System (DTS). It creates a 5.1 or 6.1 surround sound mix from a standard 2-channel stereo soundtrack. It is found on many devices such as AV receivers and games consoles, and gives a better experience for those people with a surround sound system.

DVD Audio

A digital audio format designed for DVD. Compared to a CD, the higher disc space of a DVD allows the storage and playback of higher quality audio. DVD-Audio allows high resolution stereo audio tracks up to 192 kHz/24 bit, and 5.1 surround sound up to 96kHz/24 bit resolution.

DVI

Stands for Digital Visual Interface. An interface that transmits uncompressed digital video data - but can also transmit analog video data like a VGA connection. Mainly used with flat screen LCD computer monitors and digital projectors - but is sometimes found on other devices. On a modern flat screen TV and Blu-ray player, you will usually get an HDMI connection not DVI. Follow the link for more about the DVI connector and cable.

E

Edge-lit LED TV

A type of LED TV. The LED lights behind the screen are arranged around the perimeter. This type of design allows the screen to be made very thin and also enables lower power consumption.

EDTV

Short for Enhanced Definition Television. In short, better than SDTV but not as good as HDTV. EDTV has the same number of lines of vertical information per frame as SDTV - the difference is it uses progressive scan rather than interlaced scan. So an EDTV signal can be called 480p or 576p (depending on where you live in the world). Even though there is the same amount video information as an SDTV signal, the progressive scan will produce a sharper image as it reduces the artifacts produced by interlacing.

F

Flat Screen TV

Also known as a flat panel TV. A flat screen TV is thinner and lighter than the traditional style of TV - the CRT. A flat screen TV will only be a few inches thick which makes it easier to locate in your room - and can even be hung on a wall. They come in a range of sizes from about 10 inches up to a whopping 70 inches plus. Currently, the most common types of flat screen technology are LED and OLED. Older versions that have been discontinued are LCD and plasma.

Frame/Frame Rate

A frame is each unique image, or snapshot, that a video/film camera takes while it records something. The frame rate is the number of frames that this camera takes in one second. If enough frames are taken per second - any movement in the image will be smooth and natural when seen by the human eye. A movie is traditionally shot at 24 frames per second.

G

H

HD Ready

A TV is 'HD ready' if it can accept and display at least the minimum standard for an HD signal. Therefore, this can mean 720p, 1080i or 1080p. The minimum requirement is that the TV can show a broadcast with 720 vertical lines and with a widescreen aspect ratio. In some countries, the term also requires the picture to be received via analog component or digital connections (DVI or HDMI) - which is pretty much a given with any modern display.

HD Ready 1080p

A TV can be labelled 'HD ready 1080p' if it is able to meet certain standards when displaying an HD signal. It will exceed the standards for an 'HD ready' TV. It must have minimum native resolution of 1920 x 1080 pixels (1080 vertical lines at a 16:9 aspect ratio), display the image without distortion (1 pixel for each pixel in the source image), and be enabled for HDCP.

HD DVD

Stands for High-Definition/Density DVD. Developed by Toshiba, this optical disc format for high density data storage was similar to Blu-ray. The ability to store far more data than a traditional DVD made it ideal for use with high-definition video and audio. It was discontinued in 2008 when the major content manufacturers withdrew their support and chose to go with Blu-ray technology.

HDCP

Stands for High-bandwith Digital Content Protection. A form of copy protection for digital video and audio content designed by Intel. When devices connect to each other using a DVI or HDMI interface (e.g. your Blu-ray player sends a movie to your LCD TV via an HDMI cable), the digital information that is sent can be encrypted. Both the devices (the Blu-ray and the LCD TV) talk to each other via the HDMI connection and agree if they are both HDCP compatible. When they decide they are, the Blu-ray will send the movie to the TV. This will happen transparently without your knowledge. A device which isn't HDCP compatible won't be able to receive the digital signal and will have to make do with an analog signal instead. This is to stop people making a perfect digital copy of the video/audio.

HDMI

Stands for High-Definition Multimedia Interface. An interface that transmits digital audio and video signals. This type of connection is becoming the standard way to connect modern audio-visual devices. If you are buying a new TV or Blu-ray/DVD player then it should have at least one of these. If you can, this is the connection to use rather than component or SCART connections. One HDMI cable allows the transmission of all digital video signals (including high-definition), and up to 8 channels of uncompressed digital audio (including Dolby TrueHD and DTS-HD Master Audio - with HDMI 1.3). Therefore, you have less cables running around the back of your TV - which can only be a good thing! Go here for more information on the HDMI connector and cable.

HDTV

Stands for High-Definition Television. HDTV provides images at a much higher resolution than we are used to seeing on our TV. The level of detail and life-like pictures can be astonishing to see. To be called a high-definition picture, each frame of a video signal has to have a minimum of 720 vertical lines of information with progressive scan, or 1080 vertical lines of information with interlaced scan. Therefore, 720p or 1080i are both high-definition signals - as well as the big daddy - 1080p (also known as full HD). The picture should also have a 16:9 aspect ratio (widescreen).

High-Definition

See HDTV

Home Cinema

See Home Theater

Home Theater

A term used in North America to describe a high-end home entertainment system. A basic home theater system would usually refer to a large flat screen tv or projector to display the image - and a separate amplifier and speakers for the sound. More commonly known as home cinema in Europe.

I

Image Resolution

The resolution of a TV image is defined by the number of lines of vertical data of the image by the aspect ratio of the image. For example, for HDTV the standard aspect ratio is 1.78 (16:9), and the minimum number of vertical lines per frame is 720. Therefore, 720 (vertical lines) x 1.78 = 1280 (horizontal length). So the resolution of this 720p image is said to be 1280 x 720. The resolution of an image received by your TV can vary depending on the source. This is not the same as the native resolution of the TV screen - which is fixed.

IR

Stands for infrared. A type of electromagnetic radiation that is commonly used to send control signals to household electronic devices using a remote control. Infrared remote controls have to have 'line-of-sight' with the device they are controlling i.e. they won't work through walls or doors.

Interlaced Scan

Your TV displays an interlaced picture by building each image frame in two separate passes down the screen. First, it fills the odd lines - 1, 3, 5, 7 etc. Then it goes back to the top and fills in the even lines - 2, 4, 6, 8 etc. After these two passes it will have 'drawn' one frame of an image. Each pass is known as a field. It then goes back and 'draws' frame two etc. etc. etc.... This is the traditional method used by PAL and NTSC TV signals. This technique produces an image which can appear to flicker and lack sharpness. The alternative is to use progressive scan.

J

K

L

LCD TV

A type of flat screen TV. LCD stands for liquid crystal display. An LCD screen is made up of small pixels filled with liquid crystal - and a backlight. The intensity of light in each pixel can be varied by applying an electrical signal which changes the molecular structure of the liquid crystal. Each pixel is divided into three sub-pixels (red, green and blue) by using a colour filter - and by varying the intensity of light in each - different colours can be created. By constantly changing the intensity and colour in each pixel, a TV picture can be formed. This technology is also used to produce other types of display - such as computer monitors and projectors. For more information go to the best LCD TV buyer guide.

LCoS

Stands for Liquid Crystal On Silicon. A projection technology used in some types of projector - can often be found in rear projection TVs. Similar to DLP technology, but light is reflected off a silicon chip coated with liquid crystals rather than mirrors.

LED TV

A type of flat screen TV similar to a traditional LCD TV. The difference is the backlight in an LED TV is provided by light-emitting diodes (LEDs), as opposed to a CCFL in the LCD TV - although they both have LCD screens. Confusingly, some manufacturers refer to TVs with LCD screens and LED backlights as LED TVs - and some still call them LCD TVs. For more information go to the LED TV Guide.

LFE

Stands for Low Frequency Effects. The LFE is an optional low frequency (below 120 Hz) audio track that can be part of a 5.1/7.1 audio soundtrack. It adds extra bass information in addition to the normal bass within a soundtrack. If there is no LFE track, then an AV receiver will send bass frequencies to the subwoofer from the audio that goes to all speakers - and this is dependant on the filter settings of the receiver.

Line Level

A term used to describe the strength of an audio signal. Most audio-visual devices output their audio at line level. This signal then needs to be amplified before it can be heard on a speaker. This is why we always connect a CD/DVD player to an amplifier first - rather than directly to a speaker.


LPCM

Stands for Linear Pulse Code Modulation. A method of digitally encoding/decoding audio data. It is a standard method of encoding audio on CD, DVD and Blu-ray discs.

M

N

Native Resolution

When talking about LCD or plasma displays, the native resolution is the physical size of a TV screen - measured by the amount of pixels. This can also be called the pixel dimension. The native resolution of a screen is expressed by stating the number of horizontal pixels by the number of vertical pixels. i.e. a screen that is said to have a native resolution of 1920 x 1080 will have 1920 pixels across the screen, and 1080 pixels down the screen. Generally speaking, the more pixels there are (higher resolution), the sharper the image will be. The native resolution of a display is fixed. Note: this is not the same as the image resolution.

NTSC

Stands for National Television System Committee. The NTSC system is used to encode analog TV transmissions in some parts of the world - mainly in the Americas and Japan.The term is often used to describe a 480i picture (525 lines and 60Hz refresh rate).

O

Optical Audio Connection

Also known as a TOSLINK connection. A method of transferring digital audio signals between devices. Commonly found on consumer electronic products such as DVD players and games consoles. The audio signal is converted into light and transferred via a cable made from optical fiber. Supports stereo audio and Dolby Digital/DTS 5.1 surround sound audio signals. Follow the link for more information on the optical digital audio cable and connection.

Overscan

Historically, standard-definition TVs were difficult to build accurately enough so that we could guarantee how much of a TV image they would show. Therefore, these televisions used a technique called overscan which zoomed in the image slightly to make sure there was a clean edge around the picture on the screen, all the possible screen area was used for the image, and that no transmission signals and other artifacts were visible. Programme makers made sure that they kept all the important action within an 'safe action area', therefore ensuring nobody would miss anything important. However, by using overscan we are actually losing some of the picture. On a modern HDTV or projector, this overscan feature can often be switched on or off (but not always). It is often recommended to have overscan switched on for standard definition pictures, but switched off for high-definition pictures - but ultimately it comes down to personal preference.

P

PAL

Stands for Phase Alternating Line. The PAL system is used to encode analog TV transmissions in some parts of the world - mainly in Europe and Asia.The term is often used to describe a 576i picture (625 lines and 50Hz refresh rate).

Passive Subwoofer

A subwoofer with no built-in amplifier. This type of subwoofer should receive an amplified signal from an AV receiver/amplifier. The subwoofer is basically just a housing for the speaker. Passive subwoofers won't have inbuilt volume and tone controls, as this will be done by the amplifier before sending the signal to the subwoofer. Most subwoofers designed for home cinema will be active subwoofers - and most subwoofer outputs on AV receivers will send a pre-amp signal (not amplified).

Pixel

Short for picture element. A TV screen is made up of a grid of very small dots, squares or rectangles. Each one of these is called a pixel. These pixels can each be made to display a different colour at different intensities. This is how they build an image on the screen. If you get very close to your TV, you may be able to see the individual pixels at work.

Plasma TV

A type of flat screen TV. A plasma screen is made up of small phosphor-covered pixels filled with gas. When fed with an electrical signal, the gas and the phosphor interact to create colours. These colours can be controlled to produce the TV image. Clever huh! For more information go to the plasma TV guide.

Progressive Scan

Your TV displays a progressive scan picture by building each image frame one line at a time down the screen i.e. each frame is drawn in one pass. This produces a very sharp and 'flicker-free' picture. The traditional method for displaying TV pictures is by interlaced scan - where each frame is drawn in two passes. Most modern DVD and Blu-ray players will be able to display the image using progressive scan. Most TV transmissions still use interlaced scan.

Q

R

RF

Stands for radio-frequency. Used by some remote controls to send control signals to home cinema equipment. In the home, most remote controls use infrared to transmit a control signal. However, some devices use RF remote controls which have the advantage of a greater range and the ability to work through walls and other hard surfaces.

RCA Plug

Also known as a phono plug. A common connection for audio/video cables and commonly found as input/output connectors on DVD players and TVs etc. These connections are usually coloured red and white for analog stereo audio signals, yellow for analog composite video signals and red/green/blue for analog component video signals. They are also used for coaxial digital audio connections. For more information on the RCA plug and stereo cables.

Rear Projection Television

Also known as RPT. A type of large screen TV that creates an image by using a small projector behind the screen. This used to be the main method of producing large screen TVs, but has been overtaken by LCD and plasma TVs in the last few years. The advantage of this system is that projectors can produce excellent images - however these systems tend to be rather bulky compared to LCD and plasma flat screen TVs. Traditionally CRT projectors were used in RPTs, but more recently the projectors used are either DLP, LCD or LCoS.

Refresh Rate

The refresh rate of a TV is the number of times per second the picture is 'redrawn'. The quicker a picture is redrawn, any motion will appear smoother to the human eye and it will have less flicker. This figure will be slightly different around the world due to technical differences. In a PAL region, an interlaced TV picture has a frame rate of 25 frames per second - and each frame is drawn in two passes. Therefore the refresh rate is said to be 50Hz (25 x 2). In North America the frame rate is 30 frames per second - so the refresh rate is 60Hz (30 x 2). These 50/60Hz refresh rates originated from using interlaced scan images - but they were kept as standard when progressive scan images started to be used (which are drawn in one pass). Many new TVs are increasing their refresh rates to 100/120Hz (and more) by using digital signal processing. See 100 Hz or 120Hz.

RMS

Stands for Root Mean Square. A statistical measure of something that varies over time. It is used in relation to amplifiers to get a meaningful value for the power output in watts. The RMS values of voltage and watts are multiplied to get an average value of power. It is important to work with an average power value, rather than a peak value, as this tells us more about how the amplifier will perform in the real world.

S

SACD

Short for Super Audio Compact Disc. A high resolution audio format developed by Sony and Philips, and designed to improve on the audio quality of a traditional CD. SACD is a high density disc similar to a DVD, with a much higher sampling rate than a traditional CD. This results in recordings with a wider frequency response and larger dynamic range. It also supports multi-channel audio as well as stereo.

SCART

A 21 pin connector used to connect audio-visual equipment. The 21 pins allow a SCART connector to transmit analog audio and video signals through the same cable. Mostly used for interconnecting TVs, DVD players and VCRs. A standard analog connection in Europe, but rarely used in North America. Go here for more on the SCART cable and connections.

SDTV

Short for Standard Definition Television. SDTV is basically any TV transmission with a lower resolution than Enhanced Definition Television (EDTV) or High Definition Television (HDTV). Depending on where you live, each frame of a standard definition video signal has either 480 (North America) or 576 (Europe) visible vertical lines of information. Therefore you may see an SDTV transmission described as 480i (480 lines, interlaced) or 576i (576 lines, interlaced). EDTV and HDTV produce a sharper picture than SDTV.

Soundbar

A bar with multiple speakers which is designed to be placed along the front edge of a TV screen. The idea is to improve on the sound that TV speakers provide, whilst keeping a simple setup without an AV receiver or surround speakers. The soundbar will often use audio processing techniques to imitate the effect of surround sound, without having the need for extra speakers around the room.

Speaker Sensitivity

Also known as speaker efficiency. A speaker is sent a fixed level of power (watts), and the resulting sound level is measured to give the efficiency of that speaker. A less efficient speaker will require more power to sound as loud as a more efficient speaker. Speaker sensitivity can range from about 85db (inefficient) to about 100db (efficient).

Stereoscopy

Refers to any technique that records 3-dimensional visual information. These techniques allow the creation of 3D TV images that have the illusion of depth. The basic idea is that a slightly different version of an image is delivered to each eye, and the brain then creates one 3D image.

Surround Sound

The reproduction of audio using a multi-channel system. Most of the audio we hear from TV or radio is stereo i.e. the audio is produced to sound good from two speakers in front of you. Surround sound is used in cinema and at home to add a sense of space and direction to the audio. For example, a 5.1 surround sound system uses six speakers. Front left and right (which is the equivalent of your stereo speakers), front centre (for dialogue), surround left and right (it's behind you!) and a subwoofer (for bass). A 7.1 surround sound system has two more speakers at the back. For more information go to the introduction to surround sound systems.

Subwoofer

A speaker designed to reproduce low bass frequencies. Can also just be called a sub. With one speaker dedicated to reproducing just the low end frequencies or LFE tracks, we can get a really strong bass sound. This is the one that annoys the neighbours!

S-Video

A type of component analog video. The video signal is split into two separate parts and is usually connected with a 4 pin mini-DIN cable. S-Video gives you better quality than composite video, but not as good as component video. Follow the link for more on the S-Video cable and connectors.

T

See optical audio connection.

Transducer

A device that turns one type of energy into another. A loudspeaker is an electroacoustic transducer as it turns electrical energy into sound.

Tuner

A tuner is a device which receives radio/TV signals - and it can be adjusted to receive different frequencies. In the case of a radio tuner, it will be able to tune to the frequencies of radio transmissions (FM/AM). Once received, this signal is then passed to an amplifier/speaker configuration in order to make the radio signal audible. A TV tuner will be able to tune to the frequencies of TV transmissions. You can get analog tuners for receiving analog transmissions - or these days, a digital tuner is becoming more common to receive digital transmissions.

Tweeter

A loudspeaker designed to reproduce high frequencies - usually in the region of 2 kHz to 20 kHz. A typical bookshelf speaker may have two speaker drivers - a tweeter for the high frequencies, and a woofer for the low frequencies.

U

Upconverting

Changing a video signal from one type to another - or to be precise, from a 'lower quality' video signal to a 'higher quality' video signal. For example, if we have a DVD player connected to an AV receiver with an analog component connection, but we want the AV receiver to output to the display via HDMI - then the AV receiver will need to upconvert the analog component input signal into a digital HDMI output signal. The AV receiver would also need to upconvert if the input was s-video and the output was component.

UPnP

Stands for Universal Plug and Play. A set of network protocols that allows devices on a home network to share data between each other. In terms of home entertainment, this means that a display device like a TV can display pictures or play movies that are stored elsewhere on the network - such as on a computer or NAS (Networked Attached Storage). It is easily confused with DLNA. The DLNA certification standard uses parts of the UPnP protocol - but it places stricter limits on the types of media files it supports.

Upscaling

Increasing the resolution of a low resolution video signal to a higher resolution. A video scaler is used to convert video signals from one resolution to another. For instance, a DVD player can play an SD movie (480 lines NTSC, 576 lines PAL) and upscale this image to 720 (or 1080) vertical lines to match the resolution of an HD display. This technique can make standard DVDs look much better on a high-definition TV or projector. In this example, the video scaling can be done by the DVD player or the TV/projector - and the best results will depend on which device has the best video scaler. This process is sometimes referred to as 'upconverting', but this shouldn't be confused with upconverting! - who said this stuff was easy? :-)

V

VESA

Stands for Video Electronics Standards Association. An association formed in 1989 by a number of video display manufacturers. Their aim was to set certain standards within the industry to allow common features between devices. For example, VESA compliant hole patterns define standard hole sizes on TV wall mounts and on the rear of flat panel TVs.

VGA Connector

A connection that transmits analog video signals. This port is usually found on devices as a 15 pin D-type connection. It is used mainly on computers and projectors - but they are still provided on some flat panel screens for the connection of laptops. Go to more on the VGA connector and cable.

W

Widescreen

A widescreen image has an aspect ratio that is wider and shorter than the standard 4:3 (1.33:1) aspect ratio. Typically, we mean a 16:9 (1.78:1) aspect ratio when we talk about widescreen, as this is the standard size for flat screen Tvs. However, films are traditionally shot with an even wider image size such as 1.85:1 or 2.39:1. This is why we get black bars at the top and bottom of a film on our 16:9 TV - because the original film was shot with a wider aspect ratio than our TV can show.

Woofer

A loudspeaker designed to reproduce low frequencies - usually in the region of 40 Hz to 1 kHz. A typical bookshelf speaker may have two speaker drivers - a woofer for the low frequencies, and a tweeter for the high frequencies.

X

Y

Z


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