A - Video, recording and Printing definitions

A/B Printing

Printing from original film stock which has been conformed into two rolls with alternating shots and black opaque leader.

A/B Rolls

Two or more rolls of film having alternate scenes intercut with opaque leaders in such a way that the 'A' roll presents its picture at the same time that the 'B' roll presents opaque leader, and vice versa. (Film Editing)

A/D converter

Analog-to-digital converter.

A-B roll

Videotape editing arrangement where scenes on tape are played alternately on VTRs A and B and recorded on VTR C. Typically, the final output recorded on CTR C contains some scenes from VTR A and some scenes from VTR B with transitions (cuts, mixes, wipes, etc.) between the scenes.

Above the Line

Refers to the creative elements of a production such as the writer, producer, director and actors. Literally, these are the elements which appeared above a bold line which divided standard production budget sheets. (Production)

Absorption loss

In telecommunications, attenuation of the optical signal within the fiber optic transmission medium. Usually specified in terms of dB/km.

Alternating Current. An electric current with periodically changing polarity (i.e. 60 times a second for 60Hz power). (Electricity)

AC coupling

A method of coupling one circuit to another through a capacitor or transformer so as to transmit the varying (ac) characteristics of the signal while blocking the static (dc) characteristics. In some GVG distribution amplifiers, when the ac coupling mode is selected, a feedback loop maintains the output signal at an average dc level of 0 volts regardless of APL (average picture level) or dc offset of the incoming signal.

Ac/Dc coupling

May also be called simply dc coupling Coupling between circuits which accommodates the passing of both ac and dc signals.

AC-3

See Dolby Digital

Accent Light

A light unit that emphasizes one subject. This might be a key light, a kicker, or a backlight. (Lighting)

Access Time

Amount of time it takes a CD-ROM or DVD drive to find and display the requested information. Although specified widely, access times must be used with care because there is no measuring standard. It is generally regarded to include radial positioning time (the head moves to the appropriate track), plus settling time (stops vibration), plus latency (wait for beginning of block with the wanted data)--all of which take much more time than the final read and display step. The faster hard disk drives claim access speeds of 12 milliseconds or even lower, while current CD- ROM drives claim access times of about 150 milliseconds--and some SCSI drives claim even lower access times.

Accordion fold:

Bindery term, two or more parallel folds which open like an accordion.

Acetate Base

The tranparent cellulose acetate plastic film which for years served as the backing for magnetic recording tape. (Sound Recording)

Acetone

An organic liquid chemical used in the manufacture of some types of film cement. Also used to clean film splicing equipment. (Film Editing)

Acoustics

The science of the transmission of sound waves. Generally refers to the characteristics of auditoriums, theatres and studios with respect to their design.

Action Cutting

The cutting of film from one shot to another in a way yielding the impression that action is continuous and uninterrupted. (Film Editing)

Active video

The portion of a video signal that contains picture information.

Adaptive

Able to adjust or react to a video condition or application, as an adaptive circuit. This term usually refers to filter circuits.

ADC

Analog-to-Digital Converter. An electronic device used at the input of digital audio equipment to convert analog electrical signals to digital values whose numbers represent the level and frequency information contained in the original analog signal. (Sound)

ADC

Analog-to-digital converter.

Address Track

A control/timing track on the edge of videotape which contains control data for quick and accurate location of program material.

ADR

Automatic Dialog Replacement. Also known as "looping." A process of re-recording dialog in the studio in synchronization with the picture.

Aerial Shot

An extremely high angle view of a subject usually taken from a crane or a high stationary camera position, but may also refer to a shot taken from an actual airplane or helicopter. (Production).

AES

Audio Engineering Society.

AES/EBU

Informal name for a digital audio standard established jointly by the AES and EBU organizations. The sampling frequencies for this standard varies depending on the format being used; the sampling frequency for D1 and D2 audio tracks is 48 kHz.

AFV

Audio follow video.

Against the grain:

At right angles to direction of paper grain.

AGC

Automatic gain control.

Air

To broadcast a signal.

Aliasing

Distortion in the video signal which may manifest itself in different ways.

Alignment

The adjustment of components in a system for optimum performance.

All inputs hostile

Measurement technique, particularly for crosstalk, using worst case conditions (typically, full chroma signal on all inputs other than the one under test).

All ones

A digital signal consisting of data that contains all logical ones. In telecommunications, a test signal consisting of 11111.

Alphanumeric

A display symbol set consisting of the twenty-six letters of the alphabet and the digits 0 through 9.

Alteration:

Change in copy of specifications after production has begun.

Alternate mark inversion (AMI)

In telecommunications, an encoding protocol where successive data 1's are transmitted as alternate, equal positive and negative pulses, and data 0's are sent as spaces, each of zero amplitude.

Ambient Light

General, nondirectional, room light. (Lighting)

Ambient noise

The total sound in a given are which is peculiar to that space (room tone). (Post Production)

Amplitude

The strength of an electronic signal as measure by its waveform height. (Sound)

Amplitude

The magnitude of a signal in voltage or current. Frequently expressed in terms of peak, peak-to-peak, or RMS.

Amplitude Distortion

The nonlinear relation of input and output induced harmonics which is a function of voltage fluctuations or power consumption. (Acoustics)

Amplitude modulation (AM)

A method of imposing information on a carrier signal, such as a sine wave, by varying its amplitude.

Analog

An electrical signal that continuously varies in strength as related to some form of input.

Analog

An adjective describing any signal that varies continuously as opposed to a digital signal, which contains discrete levels.

Analog component

Another name for component video, such as RGB or Y, R-Y, B-Y as opposed to digital component video.

Analog Recording

A means of recording audio or video whereby the recorded signal is a physical representation of the waveform of the original signal.

Analog-to-digital converter (ADC, A/D, A-to-D)

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

Anamorphic

An optical system having different magnifications in the horizontal and vertical dimensions of the image.

Angle of View

This is the size of the field covered by a lens, measured in degrees. However, because of the aperture masks in film, the angle of view for a given lens is generally described in terms of the height and width of a lens. (Cinematography).

Answer Print

The first print combining picture and sound which is submitted by the laboratory for the customer's approval. (Laboratory)

Anti-Aliasing

Filtering of erroneous frequencies that are created during the analog to digital conversion process. (Sound/Picture)

Aperture

A variable opening inside a lens that regulates the amount of light reaching the image plane. Also known as an iris. (Camera/Lighting)

Append mode

In video devices capable of creating key frame effects, a mode that permits new key frames to be added to an existing key frame effect to make the effect longer.

Apple Box

A box build of a strong wood or plywood which is capable of supporting weight. These may be of various sizes, the smallest of which is also known as a 'pancake' because it is nearly flat. (Lighting/Grip)

Arc

A lighting unit that generates illumination from an electrical arc between two carbon electrodes. (Lighting)