3 chip	Refers to the number of CCDs in a camera imaging system. A seperate chip is used for each of the RGB colour components. Used in DV and high-end cameras. Low-end consumer cameras use only a single CCD, resulting in much inferior picture quality.
3DVE	3-Dimensional Video Effects. In NLE, manipulation of 2D images to give a 3D appearance. Not usually attractive - used in TV.
4:1:1	A set of sampling frequencies in the ratio 4:1:1, used to digitize the luminance and colour difference components (Y,R-Y,B-Y) of a video signal. Used in PAL DVCPRO recording.
4:2:0	A set of sampling frequencies in the ratio 4:2:0, used to digitise the luminance and colour difference components (Y,R-Y,B-Y) of a video signal. Used in PAL DVCAM recording.
4:2:2	A set of sampling frequencies in the ratio 4:2:2, used to digitise the luminance and colour difference components (Y, R-Y, B-Y) of a video signal. It is the highest rate generally available, defined by the CCIR601 standard. Used in D-1, D-5, and Digital Betacam recording.
4:4:4	A set of sampling frequencies in the ratio 4:4:4, used to digitise the luminance and colour components of a video signal. Equivalent to full sampling of the image. Not generally used.
A/D	Analogue to Digital converter. A/D converts analogue to digital form. See ’quantising’.
ADR	Additional Dialogue Recording. The process of replacing actors’ lines by re-recording in a studio.
AES/EBU	Two channel digital audio standard - defined by the Audio Engineering Society and the European Broadcasting Union. Typically 32KHz, 44.1KHz and 48KHz sampling up to 24 bits, eg DAT offers 48KHz and CD 44.1KHz recording, both at 16 bit. As a professional standard refers to an interface utilising XLR connectors, whilst the prosumer version uses S/PDIF optical or RCA connectors.
AGC	Automatic Gain Control
aliasing	Defects or distortion in a video image, commonly seen as jagged edges on diagonal lines and twinkling or brightening (beating) in picture detail.
analogue	A continuous signal requiring a finite time to rise (or fall) from one level to another. The signal retains an infinite number of levels between max and min levels, as opposed to the discrete, quantised steps of digital. BetaCam SP, S-VHS, VHS, Betamax, Hi-8 and 8mm are all analogue formats.
anamorphic	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.
anti-aliasing	Reduction of aliasing effects by software techniques. Typically used to smooth the edges of on-screen text.
ARC	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.
artefact	Undesirable picture elements generated by technical limitations of the system being used. Mosquito noise (or feathering), quilting and motion blocking are three artefact types caused by use of the DCT compression algorithm.
aspect ratio	The ratio of screen width to screen height, eg standard video is 4x3 (1.33:1), widescreen video is 16x9 (1.78:1), 35mm film is 1.85:1
AVI	Audio Video Interleave. A frequently used file format for storing video (and audio, if required) information in computer.
balanced audio	A method that uses three conductors (plus, minus, ground) for a mono audio signal. The ground conductor is for shielding and does not carry any signal. This technique allows cables to be run to any length. Requires XLR connectors.
banding	A video artefact revealing visible breaks in what should be a smooth graduation. Can be caused by poor quality compression. Also, by head problems in a segmented scan system like DV.
bandwidth	A frequency range or capacity within which a system of devices operates. In effect, to transmit video or audio without loss or distortion a system must be able to sustain sufficiently high data rates, eg a critical element in the design of an NLE system is the speed of the hard drives.
batch capture	Automatic capture (’digitising’) of multiple video clips based on timecode.
Betacam	Analogue camera/recorder system using 1/2-inch tape, developed by Sony. Betacam uses a version of the Y, R-Y, B-Y colour difference signal set.
Betacam SP	A superior version of Betacam. SP uses metal particle tape and a wider bandwidth recording system.
Betacam SX	Digital camera/recorder system from Sony using 10:1 MPEG-2 compression on identical tape stock to Betacam SP.
bit	Binary digit, the smallest part of information in a binary notation system. A bit can be set as ’1’ or ’0’. The more bits per pixel of an image, the greater the number of potential colours.
black chip	Latest generation of the DMD. Central component of Texas Instruments’ ’DLP Cinema’. Features higher resolution and increased contrast ratios.
black level	See ’set-up level’.
BNC	Bayonet Neill Concelman. A cylindrical connector system with a twist-locking motion used for high frequency signals in television and digital audio.
B-Y	Also signified by ’Cb’. One of the two colour difference signals in a component video siganl, obtained by subtracting luminance from the blue video signal. This is the signal which drives the horizontal axis of a vectorscope.
byte	A collectively processed group of 8 bits.
capture	The process of transferring video footage from an external source to a computer hard drive. For analogue sources this involves an analogue to digital (A/D) conversion process, but with material shot digitally is effectively a file transfer, usually involving ’transcoding’.
capture card	A computer board that allows input (and output) of a video signal by performing the necessary file and signal conversions.
Cb	See ’B-Y’.
CCD	Charge Coupled Device. Used in digital cameras and telecines as an optical scanning mechanism, converting the light input (analogue signal) to an electrical output (digital signal).
chroma	The characteristics of colour information, independent of luminance intensity. Hue and saturation are qualities of chroma. Black, gray, and white objects do not have chroma characteristics.
chrominance	Colour part of a video signal. Conveys hue and saturation information, independent of luminance. Symbolised by ’C’.
clipping	Distortion or loss of a signal caused by overload, ie record level set too high. A notable problem in digital.
Cr	See ’R-Y’.
CODEC	Abbreviation of COmpressor/DECompressor. An algorithm (mathematical method) for translating to and from a file or compression format.
colour bars	A test pattern of six basic colours: yellow, cyan, green, magenta, red, blue. Used to check the chrominance functions of video systems.
component video	A colour video signal composed of three colour components (Red, Green, Blue) or one luminance and two colour difference components (Y, R-Y, B-Y). Provides the highest quality video image generally available.
composite video	A colour video signal derived to be compatible with the earlier monochrome video signal. Composed of one luminance element and one chrominance element. Still used for television broadcasting.
compression	A process that reduces the size of a datastream. Lossless compression enables the original data to be fully reconstituted. Lossy compression removes data, some of which may be considered redundant. Good video compression causes a minimum apparent loss of information to the viewer.
compression rate	The change in file size achieved by the process of compression. This is expressed as a ratio, eg 5:1 compression (DV formats) reduces a file to 20% of its original . The higher the ratio, the greater the potential loss of quality, though the degree of loss cannot be directly related to the compression ratio.
conform	Organisation of master material in an on-line edit according to off-line EDL.
contrast ratio	The ratio of the highlight output level to the shadow output level. In theory the contrast ratio of a video system should be at least 100:1, if not 300:1. In reality there are several limitations. In the CRT the level of a dark element is raised by adjacent elements and by ambient light. Well controlled viewing conditions yield a realistic ratio of 30:1 to 50:1. The minimum standard for DLP based digital cinema is 1000:1
cross colour	In a composite signal, the colour is represented by the phase modulation of a subcarrier frequency. If the representation of an object in the signal replicates the subcarrier it is falsely decoded as colour, resulting in a rainbow patterning or striped effect.
CRT	Cathode Ray Tube. The vacuum tube used in video monitors, comprised of an electron gun aimed at a screen coated with phosphors that glow when hit by the electron beam. The beam is scanned horizontally and vertically revealing the image lines.
CRCC	Cyclic Redundancy Check Code. A polynomial calculation of a checksum across a data track, e.g. on a tape. Averaged across a dedicated number of blocks of data, it ensures the reliability of a recording.