A ratio which defines the relationship between the height and width of a movie frame.
The Academy ratio is 1:1.375 (i.e. if the height of the image is 1 unit, the width will be 1.375 units).
Silent movies were shot in 1:1.33.
Cinemascope is 1:2.35.
A traditional TV picture is known as 4:3 (width:height, which can be expressed as 1.33:1). A widescreen TV is 16:9. (or 1.77:1)
Short for Audio-Visual, referring to projected or screened video or textual material.
A device which changes an audio or video signal from unbalanced wiring to balanced (or vice versa). The name is derived from BALanced / UNbalanced.
The term is commonly seen now for devices that adapt an analogue audio or video signal so that it can travel long distances over standard wiring (such as CAT5).
Professional video tape format developed by Sony (short for Betacam SP). Beta SP is broadcast-quality and is a relative of Sony's failed Betamax domestic standard.
A range of half-inch professional videocassette products developed by Sony in 1982. Consists of Analogue and Digital formats.
(Trade Name) Consumer-level analog videocassette magnetic tape recording format developed by Sony, released on May 10, 1975
Coaxial connector used for carrying a composite video signal or radio frequency signal. BNC stands for Bayonet Neill Concelman - after original inventors Carl Concelman and Paul Neill who developed the connector in the late 1940s. BNC is also thought to stand for 'Bayonet Nut Connector'.
A measure of the amount of light produced by a display screen, projector or light source.
Data projector brightness is measured in lumens. A lumen is a measure of the brightness of a light source.
One lux is one lumen per square meter. One lumen is one candela per square radian (to measure the light travelling outwards from a light source).
Cinema screen brightness is measured in nits. A nit is unit of visible-light intensity, commonly used to specify the brightness of a cathode ray tube or liquid crystal display computer display. One nit is equivalent to one candela per square metre.
Circular slide magazine; also refers to a 35mm slide projector using this type of magazine (Kodak trade name). See PROJECTION.
Acronym for Computer Generated Imagery. Any images or special effects sequence in a film / video which is created in computer software such as After Effects, or any motion graphics or special effects compositing software.
Shortened to Chroma or C. The signal in component video systems that contains the colour information for the picture. The monochrome part of the picture is luma or luminance.
A shielded copper cable used for satellite TV, analogue TV, video and some digital connections.
Sometimes shortened to 'Coax cable', it consists of an inner solid copper conductor surrounded by a plastic insulator, which is wrapped with a braided copper screen, with an outer protective sheath.
There are different connectors used for coaxial cable, including RF connector, threaded F type satellite TV connectors, or locking BNC connectors. There are also different types of coaxial cable, for different purposes, identified by their electrical impedance. 75 Ohm (written as 75Ω) cable is used for video, while 50 Ohm (50Ω) is used for data and radio signals.
Composite video is the format of an analog television (picture only) signal produced by video cameras (camcorder or CCTV). Connectors used are either BNC (pro / semi-pro) or RCA/phono (domestic / semi-pro). A yellow-coloured RCA/phono socket is used for composite video output or input.
TO BE DEFINED.
Cathode Ray Tube. Refers to a TV/monitor using a traditional tube (rather than a TFT / flat design)
As prices are dropping, the use of a data projector connected to a laptop or PC/Mac is within the budget of almost every performance.
See link below for more information.
Known in parts of Europe as a BEAMER.
See Multimedia Projection for Drama for more information.
Interface connected between two or more slide projectors and a tape player. Synchronisation signals recorded onto the tape are detected by the dissolve unit and fade up the lamp in one slide projector while changing the slide in the other, and then vice versa, producing a dipless crossfade between the two images.
DLP / D.L.P.
Digital Light Processing. Digital technology licenced from Texas Instruments which enables video projectors to deliver a brighter, sharper, more detailed digital image. The first DLP projectors arrived in 1996.
Dots per inch. A measure of the resolution of a printed or computer image.
Digital Video. Professional video format.
TO BE DEFINED.
Digital Versatile Disc.
Digital Visual Interface. New interface connection standard between computer and display device.
PDF article about DVI
1) Apple video editing software (originally developed by Macromedia).
2) The final (finished) edit of a film / TV programme, which the director / producer has approved.
FireWire is another name for IEEE 1394, a high speed data transmission protocol developed in the mid 1990s by Apple which is used extensively on digital video and audio equipment and on PCs.
The FireWire 800 (IEEE 1394b) operates at 800Mb per second and can transmit data over 100m cables.
Apple stopped using Firewire on Macs in 2012, and have replaced it with Thunderbolt and/or USB 3.0.
Frames per second. The UK standard is 24 fps for film, and 25 fps for television. In the USA, the TV standard is 30 fps.
1) (especially TV and Film) Jargon for a replacement lamp.
2) The glass part of a lamp.
3) The Globe Theatre in London.
See also BUBBLE, LAMP.
Widescreen (16:9) high-resolution digital TV format.
HD-TV basics website
HDBaseT is a standard for connection and transmission of high-definition video, audio and control / data signals using a Cat6 cable. The standard was launched in 2010, and can transmit up to 100m using good quality cable.
High Definition Multimedia Interface. HDMI is a proprietary audio/video interface for transferring uncompressed digital video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controller, to a compatible computer monitor, video projector, digital television, or digital audio device.
Camcorder video format designed by Sony as a follow on to its lower-quality Video 8. Uses 8mm-wide tape.
to be defined
A function available on data projectors which allows the selective stretching of the horizontal component of the projected image so that it appears to be rectangular when projected from an angle above or below the projection surface. More advanced (expensive) projectors can also keystone the vertical component of the image, and some recent projectors can automatically detect the projection surface and can automatically keystone the image to fit.
Before data projectors, special lenses were available for slide or film projectors to apply the keystone effect.
The term comes from the wedge-shape of the stone placed at the top of an arch to spread the load of the wall above equally down both sides of the arch.
LCD / L.C.D.
Liquid Crystal Display. LCD displays are in use on electrical and electronic equipment across the world, and LCD technology is also used in video projectors.
See also TFT.
How LCDs work
LED / L.E.D.
Light Emitting Diode. LED technology is becoming extremely useful in the areas of architectural lighting and video walls. LED light sources are becoming brighter and cheaper. They are extremely efficient, and give off very little heat, making them ideal for display or architectural work. LED video walls are in use all over the world - they are more efficient and lighter in weight than projection alternatives.
The LED Museum
How LEDs work
LUMEN / LUMENS
A measure of light output from a source. The brightness of video projectors is stated in Lumens.
See also LUX.
What Lumen rating projector should I use?
TO BE DEFINED.
MINI-DV / MINI DV
High quality domestic camcorder digital video format. See also DV.
Also known as a 3.5mm jack, this is found as a headphone outlet on many pieces of personal audio equipment or laptops. A minijack to twin-phono cable is used to connect from a laptop, phone or MP3 player into a sound system or mixing desk that has phono ('pin plug') input connections.
1) Drama exercise involving two performers facing one another, either side of an imaginary mirror line. One tries to exactly duplicate the movements of the other, as if they were a reflection of that person in a mirror.
2) (AV/IT) Function on a laptop computer where the built-in display output is duplicated on the projector output. Turning off mirroring enables software such as Qlab to display a cue list / controls on the laptop display while the projector output shows the media (still images, videos or live cameras) required for the show.
MP4 is a multimedia container format, which can store video, audio or still images.
See also MP3 (audio only)
What is MP4?
A digital system used in British television to provide video signals with high-quality stereo sound.
The term is an acronym for Near Instantaneous Companded Audio Multiplex. Developed in the 1970s in the UK, it was used in the 1980s as the method of compressing stereo audio to transmit it to the public. A NICAM video recorder (or a NICAM TV set) could reproduce good quality stereo sound.
Acronym for Non-Linear Editor. This is audio, video or image editing software in which the original content is not altered in the editing process.
North American Television Standards Committee. TV standard in the USA.
More about TV standards
TO BE DEFINED.
OVERHEAD PROJECTOR (OHP)
Classroom projector commonly used before digital projection became affordable, where text or images printed or drawn/written on a horizontally-placed acetate (clear plastic) film can be projected via a lens and mirror onto a vertical wall or surface. Still used for shadow-puppetry in small-scale applications (where bright, clear images can be obtained from small puppets placed on the horizontal platform), and in scenic / prop applications where a line drawing printed onto acetate can be hugely enlarged to trace onto a large piece of scenery / cloth, hung vertically.
Phase Alternate Line. TV standard in the UK and Europe.
More about TV standards
A handheld digital projector, usually battery-powered. Many different models are available, with a wide range of brightness levels (measured in Lumens). Also known as mini projector, mini beamer, pocket projector.
The ability with some advanced lighting desks and LED lighting fixtures to make each LED component within the fixture respond to a video signal. With a large number of LED fixtures, incredible fluid effects are possible that would take days to program manually.
(Trade Name) Microsoft program for displaying slides on a PC. Has become the standard for simple slide-based presentations.
(Trade Name) Software program by Adobe used for editing of digital video.
1) Slides are used to project still archive images or textures. Libraries of slides contain images for every occasion. Kodak Carousel projectors are the industry standard, and some types can be linked to a controller to perform complex dissolves and fades from one projector to another. More powerful projectors are available using very intense discharge sources and large format glass slides to produce a massive image.
2) Lighting effects : Moving cloud / rain / fire effects can be achieved using a powerful lantern known as an effects projector with a motorised glass disc painted with the required effect. An objective lens is required in front of the disc to focus the image. See Effects.
3) Gobos : See GOBO.
4) Film : 35mm film projection is common in many theatres as a device for keeping the building open to the public when productions are in preparation. 16mm film projection is used in smaller venues. Film projection can, of course, also be integrated into a performance.
5) Data: Data or Video projection is now being used to bring video and computer images to the large screen. Data projectors are considerably cheaper and more versatile than other methods, and the quality is improving all of the time. Images can be front projected or back/rear projected depending on the amount of space and the effect required. For example, if actors are required to walk in front of the screen and not have the image appearing on them, back projection is the only answer.
6) Front Projection: The projector(s) are in front of the projection surface or screen, between the screen and the audience. This results in a bright image, but means that actors standing directly in front of the screen may cast a shadow on the screen (and have projection on their faces).
7) Rear Projection / Back Projection: The projector is behind the projection surface. This means the projection image will be reversed from the point of view of the audience (all data projectors have a setting to flip or mirror the image). A standard white cloth or sheet can be used, but the image will be dimmer than it would be from the front, and (most importantly) the projector lens will be visible as a bright hot spot in the projection. To avoid this, a custom-made back projection screen should be used. Companies such as Rosco sell back projection (BP) material (a translucent plastic) which results in a very bright and clear image, and which prevents the visibility of a projection hot spot. The BP material can be stapled to a frame to form a screen of the exact size needed for the event.
See LCD, DLP, SCREEN.
Red Green Blue. Video connection standard using three connections for the three colours which make up the final image. Provides a higher quality image than standard composite video.
Video format launched by JVC in 1987. S-VHS resolution is 400 horizontal lines. See also VHS.
S-VIDEO / S VIDEO
TO BE DEFINED.
SCART is a 21-pin connector standard which transmits full video and audio signals. Also known as Peritel, Peri TV, or Euroconnector. SCART cables are sometimes uni-directional, and care needs to be taken to ensure the correct cable is used for a particular application. The cables are notoriously unreliable in heavy duty situations, and pins get broken or pushed in fairly easily. However, handled with care, and left in equipment, they are perfectly fine.
Main definition submitted by Stephen Bourke.
Stands for Serial Digital Interface. A standard for digital video transmission over 75 ohm coaxial cable, using BNC connections.
SECAM / S.E.C.A.M.
Television standard used mainly in France and former USSR. Stands for 'Séquential Couleur Á Mémoire'
Uses 625 lines of resolution like PAL and 25 frames per second, but has a colour processing system not compatible with other systems. See also PAL and NTSC.
More about TV standards
Glass (or film that can be applied to existing glass) which can make a window opaque when an electric current is passed through it.
(Trade name) A combination harness and camera support which (with practice) enables a handheld camera to appear to float through a scene. Any movements of the camera operator are cancelled out by the design of the harness.
The original Steadicam was invented in 1975 by camera operator Garrett Brown and used on projects such as Rocky and The Shining.
There are variations based on motorised gimbals which can actively cancel out any operator movements, which are much easier to use.
Tiffen Steadicam website
Super Video Graphics Array.
Thin Film Transistor. Technology used in flat screen displays (laptop computers, flat screen monitors, colour screen handheld computers and mobile phones). TFT screens are better resolution than LCD panels, but are more expensive. Sometimes known as Active-Matrix LCDs.
Each pixel is controlled by up to four transistors.
How TFTs work
Figure used to calculate how large a projected image will be for a given distance to the screen (or vice versa).
For example, a throw ratio of 2.5 means that to achieve an image 4 feet across, the projector must be (4 x 2.5 = 10) 10 feet from the screen.
A projector 8 feet from the screen will result in an image (8 / 2.5 = 3.2) 3.2 feet across.
A short throw projector with a ratio of less than 1 will produce a larger image for a smaller throw.
1) The movement of actors / scenery & change of lighting / sound between one scene and another.
2) Video: An effect applied to a change of shot / camera angle to make it anything other than a simple cut.
Triaxial Cable, often referred to as triax for short, is a type of electrical cable similar to coaxial cable, but with the addition of an extra layer of insulation and a second conducting sheath. It provides greater bandwidth and rejection of interference than coax, but is more expensive.
Acronym of Video Graphics Array. Video display standard for computers, and the generic name of the 3 row, 15 pin connector with a blue plastic infill which is used to connect an external monitor on many PC desktop and laptop models.
Video recording format invented by JVC (Japan Victor Company) in 1976. The name stands for VIDEO HOME SYSTEM. VHS resolution is 250 horizontal lines.
Compact VHS tape cassette camcorder format using the same tape as VHS in a smaller cassette. Adaptors are used to extend the cassette size so that it can be viewed in a full-size VHS player.
Term from the film industry for a base where the material being shot can be previewed and reviewed on monitor screens. Often now used for the base of the AV / projection department.
8mm domestic analogue video format. Popular between 1985 and 2007, due to the quality improvement over VHS-C, and due to the compact camcorders. The format was replaced by Mini-DV, from 1995.
See also HI-8.
VJ (Video Jockey)
An artist that mixes video into a live performance on the fly. The term derives from DJ (Disc Jockey), who plays music for club nights, parties or events.
(Short for Video Tape) A pre-recorded video clip that is played in during a live performance.
Short for eXtended Graphics Array. Computer display standard introduced by IBM in 1990. XGA offers a resolution of 1024x768 pixels with 256 colours, or 640x480 with 16 bit colour.
XGA-2 was added later and offered 1024x768 pixels with high colour, and 1360x1024 with 16 colours.