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GLOSSARY OF TERMS

A - B - C - D - E - F - G - H - I - J - K - L - M - N - O

P - Q - R - S - T - U - V - W - Z Y Z


A

Activity Detection: A feature used in multiplexers and DVRs that uses video motion detection techniques to improve the camera update times. It can also give a relay closure.

ActiveX:
ActiveX is a standard that enables software components to interact with one another in a networked environment, regardless of the language(s) used to create them. Web browsers may come into contact with ActiveX controls, ActiveX documents, and ActiveX scripts. ActiveX controls are often downloaded and installed automatically as required.

AF (Autofocus):
A system by which the camera lens automatically focuses on a selected part of the subject.

Angle of View:
The angular range that can be focused within the image size. Small focal lengths give a wide angle of view, and large focal lengths give a narrow field of view.

Aperture:
The opening of a lens which controls the amount of light reaching the surface of the pickup device. The size of the aperture is controlled by the iris adjustment. By increasing the F stop number (F1.4, F1.8, F2.8, etc.) less light is permitted to pass to the pickup device.

Alarming:
The ability of CCTV equipment to respond to an input signal, normally a simple contact closure. The response varies depending on equipment type.

Artifact
An unnatural effect not present in the original video or audio, produced by an external agent or action. Artifacts can be caused by many factors, including digital compression, film-to-video transfer, transmission errors, data readout errors, electrical interference, analog signal noise, and analog signal crosstalk. Most artifacts attributed to the digital compression of DVD are in fact from other sources. Digital compression artifacts will always occur in the same place and in the same way. Possible MPEG artifacts are mosquitoes, blocking, and video noise.

Aspect Ratio:
The ratio of the picture frame width to the picture frame height in standard TV systems. It is 4 units horizontal over 3 units vertical.

Aspherical Lens:
A lens designed with a nonspherical shape so that it refracts the light passing through it to either lower the lens aperture so that it passes more light or decrease barrel distortion on wide angle lenses.

Automatic Frequency Control (AFC):
An electronic circuit used whereby the frequency of an oscillator is automatically maintained within specified limits.

Automatic Gain Control (AGC):
An electronic circuit used by which the gain of a signal is automatically adjusted as a function of its input or other specified parameter.

Automatic Iris Lens (AI):
A lens in which the aperture automatically opens or closes to maintain proper light levels on the faceplate of the camera pickup device.

Automatic Level Control (A.L.C.):
A feature on some Auto lris lenses (also known as the peak/average control). Adjusting this control allows the Auto Iris circuitry to either take bright spots more into consideration (peak), bringing out detail in bright areas, or less into consideration (average) bringing out detail in shadows.

Auto-terminating:
A feature where the equipment (i.e. monitor) automatically selects the correct termination depending on whether the video output BNC is connected.

Auto White Balance:
A feature on colour cameras that constantly monitors the light and adjusts its colour to maintain white areas.

ATA, EIDE, IDE
Advanced Technology Attachment or called Parallel ATA is a disk drive implementation that integrates the controller on the disk drive itself. There are several versions of ATA: ATA, also called IDE.
ATA-2, also called EIDE.
Ultra-ATA, also called Ultra-DMA, ATA-33, and DMA-33.
ATA/66ATA/100

Attenuation:
A decrease or loss in a signal. Back Focal Distance: The distance from the rear most portion of the lens to the image plane.

AVC, H.264, H264
H.264, MPEG-4 Part 10, or AVC, for Advanced Video Coding, is a digital video codec standard which is noted for achieving very high data compression. It was written by the ITU-T Video Coding Experts Group (VCEG) together with the ISO/IEC Moving Picture Experts Group (MPEG) as the product of a collective partnership effort known as the Joint Video Team (JVT). The ITU-T H.264 standard and the ISO/IEC MPEG-4 Part 10 standard (formally, ISO/IEC 14496-10) are technically identical. The final drafting work on the first version of the standard was completed in May of 2003.

AVI
Audio Video Interleaved - A multimedia file format for storing sound and moving pictures in RIFF format developed by Microsoft. An AVI file can use different codecs and formats so there is no set format for an AVI file unlike for example standard VCD video which sets a standard for resolution, bitrates, and codecs used.

B - Top of Page

B Frame
One of three picture types used in MPEG video. B pictures are bidirectionally predicted, based on both previous and following pictures. B pictures usually use the least number of bits. B pictures do not propagate coding errors since they are not used as a reference by other pictures.

Bidirectional prediction
A form of compression in which the codec uses information not only from frames that have already been decompressed, but also from frames yet to come. The codec looks in two directions: ahead as well as back. This helps avoid large spikes in data rate caused by scene changes or fast movement, improving image quality.

Bitmap:
A bitmap is a data file representing a rectangular grid of pixels. It defines a display space and color for each pixel (or “bit”) in the display space. This type of image is known as a “raster graphic.” GIF’s and JPEG’s are examples of image file types that contain bitmaps

Bit rate:
Bitrate or Bit Rate is the average number of bits that one second of video or audio data will consume. Higher bitrate means bigger file size and generally better video or audio quality while lower bitrate means lower file size but worse video or audio quality. Some bitrate examples in common video and audio files:
MP3 about 128 kbps (kilobits per second)
VCD about 1374 kbps
DVD about 4500 kbps
DV about 25 Mbps (megabits per second).

Black Level:
The level of the video signal that corresponds to the maximum limits of the black areas of the picture. Backlight Compensation (BLC): A feature on cameras which electronically compensates for high background lighting to give detail which would normally be silhouetted.

Blooming:
The halation and defocusing effect that occurs around the bright areas of the picture (highlight) whenever there is an increase in the brightness intensity.

bps
Bits per second. A unit of data rate

Bridging:
A term indicating that a high impedance video line is paralleled, usually through a switch, to a source of video.

C - Top of Page

CCD:
This light-sensitive image device used in many digital cameras is a large integrated circuit that contains hundreds of thousands of photo-sites (pixels) that convert light energy into electronic signals. Its size is measured diagonally and can be 1/4”, 1/3”, 1/2” or 2/3”

C Mount/CS Mount:
CCTV lenses are available in two different lens mounts. C-mount lenses have a flange back distance of 17.5mm vs. 12.5mm forCS-mount lenses. Many of today’s cameras can accept either type of lens, but it is important to make sure that camera and lens are compatible and set up properly.

C-mount lenses can be used on CS-mount cameras by utilizing a 5mm adapter (or on some cameras by adjusting the camera for C-mount lenses). Because of the shorter back focal distance, CS-mount lenses can only be used on CS-mount cameras. Your picture will be out of focus if you use a CS-mount lens on a C-mount camera.

Conditional Refresh:
A technique used in slow and fast scan transmission equipment, as well as DVRs where only small screen changes are transmitted.

Candlepower:
The unit measure of an incident light.

CCTV:
The common abbreviation for closed circuit television.

Chroma bug
The basic "Chroma Bug" manifests itself as streaky or spiky horizontal lines running through the chroma channel, most notably on diagonal edges. As mentioned above, this problem has been around for a long time. It's only just now being noticed largely because one needs a good high-resolution display, such as a front projector and a six foot projection screen, to really see the problem clearly. In addition, the increasingly common use of large progressive displays has really allowed people to get up close to the screen and see every artifact magnified in great detail. Problems that might have gone unnoticed on a 20 inch interlaced TV suddenly hit you in the face. With the advent of relatively high resolution media like DVD, people are starting to compare the video image to the original film image, not to other forms of TV. And suddenly strange problems that people accepted in a TV picture, but would never be allowed on film, look out of place. The Chroma Bug is one of the most visible artifacts around, but because it's specific to MPEG and 4:2:0 encoding, there was nothing written about it until very recently.

Chroma Key
The Chroma Key process is based on the Luminance key. In a luminance key, everything in the image over (or under) a set brightness level is "keyed"out and replaced by either another image, or a color from a color generator. Also known as Blue Screen Compositing, the Chroma Key Process was made famous by films such as star wars where spacecraft miniatures were composited onto starfield backgrounds.

Chroma noise
Chroma noise affects areas of colour in the image. Instead of being clean, even areas of colour, chroma noise makes colours look grainy due to random noise being inserted into the colour signal. Chroma noise seems to particularly affect blue, although it can potentially be seen in any large expanse of a single colour. Chroma noise is pretty much exclusively an artefact of analogue video processing, and it is very rare to see it in modern, all-digital transfers. Increased MPEG macro-blocking artefacts are a potential side-effect of chroma noise, as the MPEG encoder attempts to encode the extra spurious random noise, leaving less bits for actual picture information.

Coaxial Cable:
A type of cable capable of passing a range of frequencies with low loss. It consists of a hollow metallic shield in which one or more center conductors are put in place and isolated from one another and from the shield.

Codec
An acronym for "compression/deccompression", a codec is an algorithm or specialized computer program that encodes or reduces the number of bytes consumed by large files and programs. Files encoded with a specific codec require the same codec for decoding. Some codecs you may encounter in computer video production are Divx, MPEG-1, MPEG-2, Xivd, DV type 1 and type 2 for video and MP3 for audio.

Codec can also mean compression/decompression, in which case it is generally taken to mean an algorithm or computer program for reducing the size of large files and programs.

Combo Drive
A DVD-ROM drive capable of reading and writing CD-R and CD-RW media. May also refer to a DVD-R or DVD-RW or DVD+RW drive with the same capability.

Component Video
A video system containing three separate color component signals, either red/green/blue (RGB) or chroma/color difference (YCbCr, YPbPr, YUV), in analog or digital form. The MPEG-2 encoding system used by DVD is based on color-difference component digital video. Very few televisions have component video inputs.

Composite Video
An analog video signal in which the luma and chroma components are combined (by frequency multiplexing), along with sync and burst. Also called CVBS. Most televisions and VCRs have composite video connectors, which are usually colored yellow.

Compression
The process of removing redundancies in digital data to reduce the amount that must be stored or transmitted. Lossless compression removes only enough redundancy so that the original data can be recreated exactly as it was. Lossy compression sacrifices additional data to achieve greater compression.

CSS
Content Scrambling System. In DVD-Video, an encryption scheme designed to protect copyrighted material that resides on a disc by periodically scrambling the data using encryption keys.

D - Top of Page

D1
A video resolution standard. In the NTSC system, "Full D1" means 720x480 pixels, and in the PAL and SECAM systems full D1 is 720x576. You also see "cropped D1", which is 704xNN, which is useful because the 8 pixels on either edge of the video frame aren't supposed to contain useful information. Therefore, some programs will prefer the cropped D1 resolution to save bandwidth. Other popular resolutions are often described in terms of D1: the SVCD resolution is 2/3 D1 (480xNN) and 352xNN is 1/2 D1. Occasionally you see SIF somewhat inaccurately described as 1/4 D1.

DSI
Data Search Information. Information for Fast Forward/Fast Backward and seamless playback. This is real time control data spread throughout the DVD-Video data stream. Along with PGCI, these packets are part of the 1.00 mbit/sec overhead in video applications (Book B). These packets contain navigation information which makes it possible to search and maintain seamless playback of the Video Object Unit (VOBU). The most important field in this packet is the sector address where the first reference frame of the video object begins. Advanced angle change and presentation timing are included to assist seamless playback.

DSL
Digital Subscriber Line - a telephone communication line that uses modulation technology to maximize the amount of data that can be sent over copper wires. DSL is used for broadband and voice connections from telephone switching stations to a subscriber with bitrates similar or slightly less than Cable Modem and greater speeds than ISDN.

DC type lens:
An Auto Iris lens which receives voltage from the camera to adjust the iris.

Depth of Field:
The front to back zone in a field of view which is in focus in the televised scene. With a greater depth of field, more of the scene, near to far, is in focus. Increasing the f-stop number increases the depth of field of the lens. Therefore, the lens aperture should be set at the highest f-stop number usable with the available lighting. The better the lighting, the greater the depth of field possible. In other words, the depth of field is the area in front of the camera which remains in focus. The larger the f-number the greater is the depth of field.

Digital:
A signal that levels are represented by binary numbers. Distribution Amplifier: A device that accepts a (video) signal and sends it out to a number of independent outputs.

Duplex (multiplexer):
A multiplexer that allows the user to look at multi-screen images while performing time multiplex recording.

Dwell Time:
The length of time a switcher holds on a camera before moving on to the next in sequence. E.I. (Electronic Iris): Automatically changes a CCD camera’s shutter to mimic Auto Iris control, allowing fixed or Manual Iris lenses to be used in a range of areas that used to require an Auto Iris lens.

E - Top of Page

E.I.A. (Electronic Industry Association):
U.S. TV standard; 525 lines, 60 fields.

Electronic Shuttering:
Electronic shuttering is the ability of the camera to compensate for moderate light changes in indoor applications without the use of auto iris lenses.

Equalization:
The process of correcting losses of certain components in a signal.

F - Top of Page

F-Number:
The f-number indicates the brightness of the image formed by the lens, controlled by the iris. A smaller f-number means a brighter image.

F-Stop:
A term used to indicate the speed of a lens. The smaller the F-number, the greater is the amount of light passing through the lens.

Fibre-Optics:
Flexible glass fibers used to conduct energy. It is valuable in the coupling of multi-stage image intensifiers.

Field:
One half of a frame, consisting of either the odd or the even numbered lines, 60 fields are transmitted every second.

Firewire
FireWire is a fast peripheral interconnect standard capable of transfer speeds up to 400 Mbs. It works well for multimedia peripherals such as DV (Digital Video) cameras and other high-speed devices like the latest hard disk drives, CD/DVD burners and printers. Apple FireWire information.

Firmware:
The firmware of a device is the program code that is permanently stored in the device's memory. It contains all the necessary software routines to make the device fully functional. New updated firmware is sometimes distributed for dvd players, cd/dvd writers and many other computer devices to add features or fix bugs.

Focal Length:
The distance from the center of the lens to a plane at which point a sharp image of an object viewed at an infinite distance from the camera is produced. The focal length determines the size of the image and the angle of the field of view seen by the camera through the lens. That is the distance from the center of the lens to the pickup device.

fps
Frames per second. A measure of the rate at which pictures are shown for a motion video image. In NTSC and PAL video, each frame is made up of two interlaced fields.

Frame:
The total area of the picture which is scanned while the picture signal is not blanked.

Frame Rate:
The frame rate used to describe the frequency at which a video stream is updated is measured in frames per second (fps). A higher frame rate is advantageous when there is movement in the video stream, as it maintains image quality throughout.

FTP (File Transfer Protocol):
FTP is an application protocol that uses the TCP/IP protocols, used to exchange files between computers/devices on networks.

Full-duplex:
Transmission of data in two directions simultaneously. In an audio system this would describe e.g. a telephone system. Half-duplex also provides bi-directional communication, but only in one direction at a time, as in a walkie-talkie system. See also Simplex.

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Garbage In Garbage Out, GIGO:
Garbage In, Garbage Out or sometimes called Crap In, Crap Out is a computer term describing the fact that the output data is only as good as the input data. It means basicly the same as a video term, the output video and audio quality can only be as good as the source video and audio quality.

Gain:
Gain is the amplification factor and the extent to which an analog amplifier boosts the strength of a signal. Amplification factors are usually expressed in terms of power. The decibel (dB) is the most common way of quantifying the gain of an amplifier.

Gateway:
A gateway is a point in a network that acts as an entry point to another network. In a corporate network for example, a computer server acting as a gateway often also acts as a proxy server and a firewall server. A gateway is often associated with both a router, which knows where to direct a given packet of data that arrives at the gateway, and a switch, which furnishes the actual path in and out of the gateway for a given packet

Ground Loop:
Caused by different earth potentials in a system. Affects video pictures in the form of a black shadow bar across the screen or as a tearing in the top corner of a picture.

GUI:
A GUI (usually pronounced GOO-ee) is a Graphical User Interface to a computer. As you read this, you are looking at the GUI or graphical user interface of your particular Web browser. The term came into existence because the first interactive user interfaces to computers were not graphical; they were text-and-keyboard oriented and usually consisted of commands you had to remember and computer responses that were infamously brief. The command interface of the DOS operating system (which you can still get to from your Windows operating system) is an example of the typical user-computer interface before GUIs arrived. An intermediate step in user interfaces between the command line interface and the GUI was the non-graphical menu-based interface, which let you interact by using a mouse rather than by having to type in keyboard commands.

H - Top of Page

Half D1:
An MPEG-2 video encoding mode in which half the horizontal resolution is sampled (352x480 for NTSC, 352x576 for PAL). See also D1





HDMI
HDMI (High-Definition Multimedia Interface) is the first industry-supported, uncompressed, all-digital audio/video interface. HDMI provides an interface between any audio/video source, such as a set-top box, DVD player, and A/V receiver and an audio and/or video monitor, such as a digital television (DTV). HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio on a single cable. It transmits all ATSC HDTV standards and supports 8-channel digital audio, with bandwidth to spare to accommodate future enhancements and requirements.

Horizontal Resolution:
The maximum number of individual picture elements that can be distinguished in a single scanning line.

Hub:
A (network) hub is used to connect multiple devices to the network. The hub transmits all data to all devices connected to it, whereas a switch will only transmit the data to the device it is specifically intended for.

HVD:
HVD is an Asian standard of advanced high-definition technology originally developed in China by AMLogic Inc., for high-definition video. The format resolutions support 720p, 1080i, or 1080p on version 1 discs. Version 2 of the format added high-resolution beyond the standard fare of HD for use on non-TV monitors that support higher resolutions, up to 1880p.

I

IEEE 802.11:
A family of standards for wireless LANs. The 802.11 standard supports 1 or 2 Mbit/s transmission on the 2.4 GHz band. IEEE 802.11b supports data rates up to11 Mbit/s on the 2.4 GHz band, while 802.11g allows up to 54 Mbit/s on the 5 GHz band.

i.Link:
The Sony term for IEEE1394 or Firewire

IEEE1394:
The standard name for Firewire

Image Size:
Reference to the size of an image formed by the lens onto the camera pickup device. The common standards are 1/3” and 1/4” measured diagonally. Incident Light: The light that is falling directly over an object.

Insertion Loss:
The signal strength loss that occurs when a piece of equipment is inserted into a line.

Interlacing:
Interlaced video is video captured at 50 pictures (known as fields) per second, of which every 2 consecutive fields (at half height) are then combined into 1 frame. Interlacing was developed many years ago for the analog TV world and is still used widely today. It provides good results when viewing motion in standard TV pictures, although there is always some degree of distortion in the image.

Interleaving:
A method used in alarms or activity detection which allows extra frames of video from alarmed cameras to be added to a time multiplexed sequence while a state of alarm exists.

IP (Internet Protocol):
The Internet Protocol is a method transmitting data over a network. Data to be sent is divided into individual and completely independent “packets.” Each computer (or host) on the Internet has at least one address that uniquely identifies it from all others, and each data packet contains both the sender’s address and the receiver’s address.

The Internet Protocol ensures that the data packets all arrive at the intended address. As IP is a connectionless protocol, which means that there is no established connection between the communication end-points, packets can be sent via different routes and do not need to arrive at the destination in the correct order.

Once the data packets have arrived at the correct destination, another protocol - Transmission Control Protocol (TCP) – puts them in the right order.

IP address:
An IP address is simply an address on an IP network used by a computer/device connected to that network. IP addresses allow all the connected computers/devices to find each other and to pass data back and forth.

To avoid conflicts, each IP address on any given network must be unique. An IP address can be assigned as fixed, so that it does not change, or it can be assigned dynamically (and automatically) by DHCP.

An IP address consists of four groups (or quads) of decimal digits separated by periods, e.g. 130.5.5.25. Different parts of the address represent different things. Some part will represent the network number or address, and some other part will represent the local machine address. See also IP (Internet Protocol).

IP Camera:
The terms IP camera, network camera and Internet camera all refer to the same thing - a camera and computer combined in one unit. It operates as stand-alone unit and only requires a connection to the network.

Infrared (IR):
Infrared radiation is radiation at a longer wavelength than visible light, which means it cannot be seen by the naked human eye. As infrared radiation can be detected as heat, this can be shown on a screen or captured by a digital camera, with hotter objects showing up brighter against colder surroundings (e.g. a human body against a colder background).

As color cameras can “see” infrared radiation as well as visible light, these cameras are equipped with an IR-cut filter, to prevent distortion of the colors the human eye can see. To use the camera in very dark locations or at night, this filter can be removed, to allow infrared radiation to hit the image sensor and thus produce images.

An infrared lamp can be used for improved illumination for night surveillance, whilst not producing any extra visible light.

ISO:
Besides the standards organization, this is a CD/DVD image format somewhat similar to a BIN/CUE image fileset, but the one single .ISO file contains both: the data and the CD/DVD layout information. These types of images can be burned with several CD /DVDburning programs.

ISO 9660:
An ISO 9660 file system is a standard CD-ROM file system that allows you to read the same CD-ROM whether you're on a PC, Mac, or other major computer platform. The standard, issued in 1988, was written by an industry group named High Sierra. Almost all computers with CD-ROM drives can read files from an ISO 9660 file system. There are several specification levels. In Level 1, file names must be in the 8.3 format (no more than eight characters in the name, no more than three characters in the suffix) and in capital letters. Directory names can be no longer than eight characters. There can be no more than eight nested directory levels. Level 2 and 3 specifications allow file names up to 32 characters long.

L - Top of Page

Lag:
The image retention of an object after the object has been scanned. Sometimes, it causes smearing effect.

Level Control:
Main iris control. Used to set the Auto Iris circuit to a video level desired by the user. After set-up, the circuit will adjust the iris to maintain this video level in changing lighting conditions. Turning the control toward High will open the iris, toward Low will close the iris.

Line Lock:
To synchronize the field sync pulses of an AC powered camera to the frequency of the voltage input (line voltage).

Lossless Compression:
Compression techniques that allow the original data to be recreated without loss. Contrast with lossy compression.

Lossy Compression:
Compression techniques that achieve very high compression ratios by permanently removing data while preserving as much significant information as possible. Lossy compression includes perceptual coding techniques that attempt to limit the data loss to that which is least likely to be noticed by human perception.

Looping:
A term indicating that a high impedance device has been permanently connected in a parallel to a video source.

Lux:
A unit of measuring the intensity of light. (1 FC–approximately 10 lux).

M - Top of Page

Manual Iris Lens:
A lens with a manual adjustment to set the iris opening (F-Stop) in a fixed position. Generally used for fixed lighting applications

Matrix Switcher:
A switcher able to route any of its (camera) inputs to any or all of its (monitor) outputs, they often include telemetry control.

MAC address (Media Access Control address):
A MAC address is a unique identifier associated with a piece of networking equipment, or more specifically, its interface with the network. For example, the network card in a computer has its own MAC address.

Minimum Object Distance (M.O.D.):
The closest distance a given lens will be able to focus upon an object. This is measured from the vertex (front) of the lens to the object. Wide angle lenses generally have a smaller M.O.D. than large focal length lenses.

MJPEG:
Moving JPEG. A moving image which is made by storing each frame of a moving picture sequence in JPEG compression, then decompressing and displaying each frame at rapid speed to show the moving picture.M-JPEG does not use interframe coding as MPEG does. Sometimes called Motion JPEG.

MPEG-1:
An ISO/IEC (International Organization for Standardization/ International Electrotechnical Commission) standard for medium quality and medium bitrate video and audio compression. It allows video to be compressed by the ratios in the range of 50:1 to 100:1, depending on image sequence type and desired quality. The encoded data rate is targeted at 1.5Mb/s - this was a reasonable transfer rate of a double-speed CD-ROM player (including audio and video). VHS-quality playback is expected from this level of compression.

MPEG-2:
An encoding standard designed as an extension of the MPEG-1 international standard for digital compression of audio and video signals. MPEG-1 was designed to code progressively scanned video at bit rates up to about 1.5 Mbit/s for applications such as CD-i. MPEG-2 is directed at broadcast formats at higher data rates; it provides increased support for efficiently coding interlaced video, supports a wide range of bit rates and provides for multichannel surround sound coding such as PCM, Dolby Digital, DTS and MPEG audio.

MPEG-3:
A proposed variant of the MPEG video and audio compression algorithm and file format. MPEG-3 was intended as an extension of MPEG-2 to cater for HDTV but was eventually merged into MPEG-2.

MPEG-4:
An ISO/IEC standard 14496 developed by the Moving Picture Experts Group (MPEG), the committee that also developed MPEG-1 and MPEG-2. These standards made interactive video on CD-ROM, DVD and Digital Television possible. MPEG-4 is the result of another international effort involving hundreds of researchers and engineers from all over the world. MPEG-4 was finalized in October 1998 and became an International Standard in 1999. The fully backward compatible extensions under the title of MPEG-4 Version 2 were frozen at the end of 1999, to acquire the formal International Standard Status early in 2000.

Monochrome:
Having only one colour. In television it is black and white.

Multiplexer:
A multiplexer is a high-speed switch that provides full-screen images from up to 16 analog cameras. Multiplexers can playback everything that happened on any one camera with no interference from the other cameras on the system.

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N/D (Neutral Density) Filter:
A filter that attenuates light equally over the whole visible spectrum.

Noise:
Irrelevant, meaningless, or erroneous information added to a signal by the recording or transmission medium or by an encoding/decoding process. An advantage of digital formats over analog formats is that noise can be completely eliminated (although new noise may be introduced by compression).

NTSC:
Abbreviation of National Television Standards Committee. The NTSC is responsible for setting television and video standards in the United States (in Europe and other parts of the world, the dominant television standards are PAL and SECAM). The NTSC standard for television defines a composite video signal with a refresh rate of 60 fields (half-frames interlaced) per second. Each frame contains 525 lines and can contain 16 million different colors. The resolution of an NTSC VCD is 352x240 pixels, an NTSC SVCD is 480x480, and an NTSC full D1 DVD is 704 or 720 x 480.

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PAL:
Short for Phase Alternating Line, the dominant television standard in Europe. The United States uses a different standard, NTSC. PAL delivers 625 lines at 50 fields (half-frames interlaced) per second. The resolution of a PAL VCD is 352x288 pixels, a PAL SVCD is 480x576, and a PAL full D1 DVD is 704 or 720 x 576.

Passive:
A non-powered element of a system.Peak-to-Peak: The amplitude difference between the most positive and the most negative excursions of a signal.

Pixel:
The smallest picture element of an image (one sample of each color component). A single dot of the array of dots that makes up a picture. Sometimes abbreviated to pel. The resolution of a digital display is typically specified in terms of pixels (width by height) and color depth (the number of bits required to represent each pixel).

Pixel Aspect Ratio, PAR:
The ratio of width to height of a single pixel. Often means sample pitch aspect ratio (when referring to sampled digital video). Pixel aspect ratio for a given raster can be calculated as y/x multiplied by w/h (where x and y are the raster horizontal pixel count and vertical pixel count, and w and h are the display aspect ratio width and height). Pixel aspect ratios are also confusingly calculated as x/y multiplied by w/h, giving a height-to-width ratio.

Power:
The rate at which electrical energy is applied to or taken from a device. It is expressed in terms of watts or milliwatts.

Progressive scan, Progressive, Noninterlaced, Non-Interlaced:
Progressive or non-interlaced scanning is any method for displaying, storing or transmitting moving images in which the lines of each frame are drawn in sequence. This is in contrast to the interlacing used in traditional television systems.

Q

Quantize Matrix:
A term used in all mpeg video encoders, both software and hardware, which refers to the two 8x8 blocks of numbers appearing under the Quantize Matrix tab in the settings on some encoders or hard coded. These blocks of numbers represent the mathematical functions that the encoder will perform in order to best optimize the video for the appropriate format. Settings vary between a video being encoded as computer animation intended for a computer monitor or full motion video intended for a television. Different Matrix are used for progressive frame and interlaced and also the matrix varies (should) dependent on bit rate.

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RAID:
Redundant Array of Independent Disks - a method used to standardize and categorize fault-tolerant disk systems. RAID levels provide various mixes of performance, reliability, and cost. Three of the the most implemented RAID levels are Level 0 (striping), Level 1 (mirroring), and Level 5 (RAID-5). RAID disk systems may offer advantages during video capture.

Random Interlace:
A scanning technique commonly used in CCTV systems in which there is no external control over the scanning process. That is, there is no fixed relationship between adjacent lines and successive fields.

Range Finder:
Used to determine the focal length needed and what the picture will look like on the monitor. The user looks through the device and adjusts the range finder to the desired picture. Numbers on the outside of the range finder indicate the focal length needed. Reflected Light: The scene brightness or the light being reflected from a scene. Usually it represents 5 to 95 percent of the incident light, and it is expressed in foot-lamberts.

Resolution:
1) A measurement of relative detail of a digital display, typically given in pixels of width and height;

2) the ability of an imaging system to make clearly distinguishable or resolvable the details of an image. This includes spatial resolution (the clarity of a single image), temporal resolution (the clarity of a moving image or moving object), and perceived resolution (the apparent resolution of a display from the observer's point of view). Analog video is often measured as a number of lines of horizontal resolution over the number of scan lines. Digital video is typically measured as a number of horizontal pixels by vertical pixels. Film is typically measured as a number of line pairs per millimeter;

3) the relative detail of any signal, such as an audio or video signal. Also see lines of horizontal resolution.

RGB:
Video information in the form of red, green, and blue tristimulus values. The combination of three values representing the intensity of each of the three colors can represent the entire range of visible light.

Roll:
A loss of vertical sync which causes the picture to move up or down on the TV screen.

RS232:
A commonly used computer serial interface.

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SATA:
Serial ATA is an evolution of the Parallel ATA storage interface. Serial ATA is a serial link, a single cable with a minimum of four wires creates a point-to-point connection between devices. Transfer rates for Serial ATA begin at 150MBps.

SCSI:
Small Computer System Interface is a standard electronic interface between a computer and its peripherals (hard drives, CD and DVD Readers and Writers and other peripherals).

SECAM:
Séquential Couleur Avec Mémoire/Sequential Color with Memory. A composite color standard similar to PAL (image format 4:3, 625 lines, 50 Hz and 6 Mhz video bandwidth), but currently used only as a transmission standard in France and a few other countries. Video is produced using the 625/50 PAL standard and is then transcoded to SECAM by the player or transmitter. br>
Sensitivity (pickup device):
The amount of current developed per unit of incident light. It can be measured in watts with the projection of an unfiltered incandescent source of light at 2870k degrees to the pickup device surface area. It can be then expressed in footcandles.

Signal to Noise Ratio:
The ratio between a useful video signal and unwanted noise. Spot Filter: A small insert used in a lens to increase the f-stop range of the lens.

S/N (Signal to Noise) Ratio:
Measure of noise levels of a video signal: the higher the number the better.

Sync:
Electronic pulses that are inserted in the video signal for the purpose of assembling the picture information in the correct position.

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Tearing:
A picture condition in which horizontal lines are displaced in an irregular manner.

Termination:
A non-inductive resistor that has the same resistance as the characteristic of the cable being used.

Time Base Corrector (T.B.C.):
An electronic circuit that aligns unsynchronized video signals before signal processing. Used in multiplexers and quad splitters. V

U

USB, USB2:
Universal Serial Bus is the solution for all PC users who want an instant, no-hassle way to connect new hardware like digital joysticks, scanners, digital speakers, digital cameras or a PC telephone to their computer. USB makes adding peripheral devices extremely easy. With USB-compliant PCs and peripherals, you just plug them in and turn them on. USB 2.0 (USB2) is the latest USB technology. This technology is approximately forty times faster than the previous USB 1.1 technology, increasing the speed of the device to PC connection from 12Mbps on USB 1.1 to up to 480Mbps on USB 2.0

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Vertical Interval:
The time of vertical retrace.

Vertical Retrace:
The return of the electron beam to the top of a television picture tube screen or a camera pickup device target at the completion of the field scan.

Video Motion Detection:
A system that uses the video signal from a camera to determine if there is any movement in the picture and set off an alarm.

Video Type Lens:
An Auto Iris lens without an internal circuit to control the iris. All iris control voltages come from a circuit located within the camera.

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Wide Dynamic:
The ability of the camera to accurately represent the wide range of intensity levels found in scenes that range from direct sunlight to shadows.

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Zoom Lens:
A lens system that may be effectively used as a wide angle, standard or telephoto lens by varying the focal length of the lens.

Zoom Ratio:
The ratio of the starting focal length (wide position) to the ending focal length (telephoto position) of a zoom lens. A lens with a 10x zoom ratio will magnify the image at the wide angle end by 10 times.



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