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Terms and Glossary

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A to D converter (analog-to-digital)

A circuit that uses digital sampling to convert an analog signal into a digital representation of that signal


Additional Dialogue Recording. The process of replacing actors' lines by re-recording in a studio.

Advanced Authoring Format (AAF)

This is a file type used by Avid Media Composer that contains information about video and audio clips, including metadata and sequence information.

Advanced Television Enhancement Forum (ATVEF)

A standard for combining intellectual property (IP) data with television video.

Advanced Television Systems Committee (ATSC)

Committee established by the FCC to define new standards for publicly regulated broadcast television in the United States.


Audio Engineering Society. AES is a professional organisation that recommends standards for the audio industries


Informal name for a digital audio standard established jointly by the Audio Engineering Society and the European Broadcasting Union organisations. This audio standard is formally known as AES3 but may also be informally called AES/EBU audio or simply AES audio


A digital audio standard defined in 1992 by the AES/EBU


A digital audio standard defined and updated in 2001 by the AES/EBU


Active Format Description. AFD is intended to guide DTV receivers and/or intermediate professional video equipment regarding the display of video of one aspect ratio on a display of another aspect ratio


Automatic Gain Control


Defects or distortion in a video image, commonly seen as jagged edges on diagonal lines and twinkling or brightening (beating) in picture detail.

Alpha Channel

In electronic production and post-production, there is increasing application of 4:4:4:4 encoding ---- which provides full-bandwidth R', G', and B' plus the additional alpha channel to carry processing information. An adaptation from computer graphics, the alpha channel may contain information for linear key, for luminance and/or chroma transparency, for variable edge enhancement, and similar image-processing information


Level or intensity of Signal.

Analog Video / Analog Audio

A video or audio stream encoded into the voltage amplitudes of an electromagnetic wave


A type of waveform signal that contains information such as image, voice, and data. analogueueue signals have unpredictable height (amplitude) and width (frequency) and can vary infinitely over a given range.


Denotes a difference in magnification along mutually perpendicular axes. Typically, a scene is compressed laterally during recording and expanded during playback. Allows 'letterbox' or 'widescreen' images to be captured on standard format cameras. The effect can be obtained either optically or electronically.


Reduction of aliasing effects by software techniques. Typically used to smooth the edges of on-screen text.

Aperature, camera

The available maximum dimensions of the optical image on the active surface of the photo-sensor, within which good quality image information is being recorded. The camera aperture determines the maximum usable scene information captured and introduced into the system, and available for subsequent processing and display

Aperature, clean

The clean aperture in a video digital system defines an inner picture area (within the production aperture) within which the picture information is subjectively uncontaminated by all edge transient distortions

Aperature, production

A production aperture for a studio digital video signal defines an active picture area produced by signal sources such as cameras, telecines, digital video tape recorders, and computer-generated pictures. It is recommended that all of this video information be carefully carefully produced, stored, and properly processed by subsequent digital equipment

Aperature, safe action

A safe action aperture indicates the safe action image area within which all significant action must take place, to ensure visibility of the information on the majority of home television receivers

Aperature, safe title

A safe title aperture indicates the safe title image area, within which the most important information must be confined, to ensure visibility of the information on the majority of home television receivers


Aspect Ratio Conversion. A process that crops or distorts the image to suit different display formats, eg convert 16:9 footage to 4:3. High end versions use software interpolation to compensate for loss of information.


An in-camera film timecode system, exposed in the camera during filming, carries machine-readable data (a modulated series bars similar to SMPTE LTC for each film frame). ARRI Code specifically contains the production timecode data, hour, minute, second, frame, year, month, day, and camera ID. ARRI Code is readable by Evertz UV series reader heads and model 5550 Universal decoder


A defect or distortion of the image, introduced along the sequence from origination and image capture to final display

Aspect ratio

Ratio between the width and height of the video image. Standard National Television System Committee (NTSC), phase-alternation line (PAL), Advanced Television Systems Committee (ATSC) (standard definition) and digital video broadcasting (DVB) (standard definition) use a 4:3 ratio; ATSC and DVB high-definition formats use a 16:9 format.

Assemble Edit

Editing where material is combined to produce

Asynchronous serial interface (ASI)

Transmission standard defined by the digital video broadcast (DVB) used to connect video delivery equipment within a cable, satellite, or terrestrial plant.


Ancillary Time Code.


Device designed to reduce the strength of an audio or radio signal.

Audio Dub

Re-recording the audio track of a video recording

AVC-I 100

HD Codec specified in the DPP file delivery specification for finished programmes. It uses a bit rate of 100 Mbs. It can be recorded by some Panasonic cameras and is supported as a native codec by some NLEs.

Average Picture Level (APL)

In video systems, the average level of the picture signal during active scanning time integrated over a frame period; defined as a percentage of the range between blanking and reference white level


Audio Video Interleave. A frequently used file format for storing video (and audio, if required) information in computer.


Whilst a company name, it is often used to refer to Avid Media Composer, the NLE suite they produce (although they offer other post-production tools).


Angle between the gap of a tape head and the plane of head to tape movement.


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