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Glossary
Many of the following definitions are excerpts from articles on Wikipedia or are slight rewrites from them. For more information look up articles there as Wikipedia is getting comprehensive also with regards to terms of video technology and production.
Acquisition
Video acquisition is generally understood to be the period of filming, gathering video, footage and so forth.
Aspect ratio
The aspect ratio of an image is its displayed width divided by its height (usually expressed as "x:y" or "x×y," with the joining colon or multiplication symbol articulated as the preposition "by" or sometimes "to"). For instance, the aspect ratio of a traditional television screen is 4:3, or 1.33:1
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Authoring
See ‘DVD authoring’
Bars and tone
Colour bars are a type of television test pattern, a reference, used to calibrate or trouble shoot, connections, monitors and other video equipment. ’Tone’ is a continuous 1000 Hz audio tone also used as a reference to adjust the equipment or to assert ownership of the transmission line or medium. It is common to record approximately 30 seconds of bars-and-tone in the beginning of a tape.
Bitrate
In digital multimedia, bitrate is the number of bits used per unit of time to represent a continuous medium such as audio or video after source coding (data compression). In this sense it corresponds to the term digital bandwidth consumption, or ‘goodput’.
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CCD
A charge-coupled device (CCD) is an image sensor used in most video cameras today, consisting of an integrated circuit containing an array of linked, or coupled, light-sensitive capacitors. This device is also known as a Color-Capture Device.
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Chroma
Short for chrominance, the signal used in video systems to carry the colour information while luma or luminance is the signal used to carry the brightness the image.
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Compression
A process of encoding the image information using less data than an un-encoded, or “uncompressed”, sample would use. Compressions are used to save bandwidth and storage space.
Crane
The device to make crane shots; a shot taken by a camera on a crane. The most obvious uses are to view the actors from above or to move up and away from them, a common way of ending a movie. But some filmmakers like to have the camera on a boom arm just to make it easier to move around between ordinary set-ups.
CRT
The cathode ray tube (CRT), invented by German physicist Karl Ferdinand Braun in 1897, is an evacuated glass envelope containing an electron gun (a source of electrons) and a fluorescent screen, usually with internal or external means to accelerate and deflect the electrons. When electrons strike the fluorescent screen, light is emitted. CRTs are used to refer to traditional televisions and monitors, i.e. pre flat screen type of monitor.
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Directional microphones can be built to register more sound from specific directions. This is called directionality or the polar pattern of the microphone. A ‘shot gun’ microphone is often used because they are most significantly sensitive in the frontal direction, i.e. the direction of the lens in the camera. For more on microphones follow this link:
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Dolly
In film and video production, a camera dolly allows a films camera to move on wheels while filming.
Downsampling (or subsampling) is the process of reducing the sampling rate of a signal. This is usually done to reduce the data rate or the size of the data.
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DVCPRO HD
A video recording format by Panasonic for high definition video. The bitrate is approximately 100Mbps.
DVD authoring describes the process of creating a DVD video that can be played on a DVD player.
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Electronic gain
See ‘gain’.
Field of view
The field of view (also field of vision) is the angular extent of the observable world that is seen at any given moment. In photography, angle of view describes the angular extent of a given scene that is imaged by a camera. It parallels, and may be used interchangeably with, the more general visual term field of view.
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FireWire is Apple Inc.'s brand name for the IEEE 1394 interface (although the 1394 standard also defines a backplane interface). It is also known as i.Link (Sony’s name). It is a personal computer (and digital audio/digital video) serial bus interface standard, offering high-speed communications and isochronous real-time data services. FireWire has replaced Parallel SCSI in many applications, due to lower implementation costs and a simplified, more adaptable cabling system. What FireWire does is similar to what USB does, but FireWire is in practise faster. Because of the speed and capacity many amateur and semi professional digital video camcorders use the FireWire interface to connect to a computer. There are two variations of FireWire. The first one is now known as FireWire400, the number referring to the speed of the interface and a newer interface called FireWire800 which is twice as fast as its predecessor.
Focal length
The focal length of an optical system is a measure of how strongly it converges (focuses) or diverges light. The focal length determines the angle of view, and the size of the image relative to that of the object. The longer the focal length the closer the subject appears. In practice in this context focal length determines how wide or how tele the lens is, or how “zoomed in” the image is.
Format
Video format refers to several storage formats for moving pictures: digital video formats, including DVD, QuickTime, and MPEG-4; and analogue videotapes, including VHS, Betamax, U-Matic and Digital Betacam.
Gain
In electronics, gain is a measure of the ability of a circuit to increase the amplitude or power of a signal. It is usually defined as the mean ratio of the signal output of a system to the signal input of the same system. It may also be defined as the decimal logarithm of the same ratio.
Audio gain on a video camera: In practise when one controls the audio gain of a camera one adjusts the recording level of the audio.
Image gain on a video camera: By increasing video gain in a camera one makes the image brighter, but only by pushing the levels “artificially” up, which means that only a small portion of the range of the sensor is being used and amplified electronically more. This results in a less exact and therefore a more grainy image. The more gain you add the more noise you add to the image.
Gain the channels separately
In this context ‘gain the channels separately’ means setting the recording level separately on the left and the right channels that are being recorded with the camera.
HDV
High Definition Video is a video format designed to record compressed HDTV video on standard DV media (DV or MiniDV cassette tape).
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High definition(HD) is a generic term for format and standards for displaying moving images that have significantly higher resolution than traditional television formats such as PAL and NTSC which are referred to as SD or standard definition.
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Interlaced footage
Interlaced refers to the scanning method of the video system. With progressive scan, an image is captured, transmitted and displayed in a path similar to text on a page: line by line, from top to bottom. The interlaced scan pattern in a CRT (cathode ray tube) display completes such a scan too, but only for every second line. This is carried out from the top left corner to the bottom right corner of a CRT display. This process is repeated again, only this time starting at the second row, in order to fill in those particular gaps left behind while performing the first progressive scan on alternate rows only.
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LCD
A liquid crystal display (commonly abbreviated to LCD) is a thin, flat display device made up of any number of colour or monochrome pixels arrayed in front of a light source or reflector. It is prized by engineers because it uses very small amounts of electric power, and is therefore suitable for use in battery-powered electronic devices.
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Luma
Short for luminance. As applied to video signals, luma represents the brightness in an image (the "black and white" or achromatic portion of the image). Luma is typically paired with chroma.
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Manual gain
See ‘gain’
NTSC
A colour encoding system used in broadcast television systems in many parts of the world including USA and Japan.
OnLocation (formerly known as DV Rack)
Software by Adobe for PC used to monitor amongst other things waveforms, vectorscopes and to record video onto the computer from a camera. It is mostly used in the field, hence the name.
See ‘Scope Box’
PAL
A colour encoding system used in broadcast television systems in large parts of the world including most of Europe.
Pans
Panning refers to the horizontal movement or rotation of a film or video camera, or the scanning of a subject horizontally on video or a display device.
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Post-production occurs in the making of audio recordings, films/movies, photography and digital art, videos and television programs. It is the general term for all stages of production occurring after the actual recording and ending with the completed work.
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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.
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Saturation
In colour theory, saturation or purity refers to the intensity of a specific hue. A highly saturated hue has a vivid, intense colour, while a less saturated hue appears more muted and grey.
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Scope Box
Software, similar to OnLocation, for Macs that includes a Preview Monitor, Waveform, Vectorscope, Audio Meters, Direct Disk Recorder, Luminance Histogram, RGB Histograms, and RGB Parade.
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Shot list
A shot list is a continuous sequence of video uninterrupted by edits, created of a series of frames. While planning a filming session it can be useful to write a list of shots describing each shot that needs to be filmed.
Solid state
The term solid state was introduced in the 1960s to describe electronic devices whose circuits contained neither vacuum tubes nor mechanical devices such as relays, as transistors replaced vacuum tubes in most consumer electronics. In the context of this module it refers to data storage such as flash cards that contain no moving parts as opposed to for example hard drives.
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Standard definition
Refers to the traditional television systems such as PAL and NTSC which are not HD or High definition.
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Subsampling
See ‘downsampling’
Versioning is the process of making multiple versions of the same video programme. The versions can for example differ in lengths and resolution.
Waveform monitor
A waveform monitor is a special type of oscilloscope used in television applications. It is typically used to measure and display the level, or voltage, of a video signal with respect to time. It is used as a reference to measure the attributes of a video image, for making adjustments. Today waveform monitoring is often done with a computer and not with an actual oscilloscope.
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White balance
Different light sources emit light that have different colours. The brain compensates for this by making a white surface look white in most lights, but a device like a video camera that captures the image technically does not know what white is so it needs to be told that. By manually or automatically indicating what is white, the camera will calibrate all the colours according to that reference point.
Zebra patterning is a feature found on some prosumer and most professional video cameras to aid in correct exposure. When enabled, areas of the image over a certain threshold are filled with a striped or cross-hatch pattern. Often, two thresholds are available: 80% and 100%. The former is useful for correctly exposing skin tones, while the latter is used to ensure overall scene exposure is correct. |
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