A/B ROLL EDITING
Editing from two source VCRs ("A" and "B") to a third (recording) VCR. Typically a switcher or mixer, such as the Digital Video Mixer, is used to provide transition effects between sources. Control over the machines and process can be done manually or automatically using an edit controller.
ALIASING
Undesirable video display effects caused by too much high frequency video information. Examples: a.) Temporal aliasing - e.g., rotating wagon wheel spokes apparently reversing direction; b.) Raster scan aliasing - e.g., twinkling or strobing effects on sharp horizontal lines; c.) Stair-stepping - Stepped or jagged edges of angled lines, e.g., at the slanted edges of letters.
ANALOG
A method of representing data using continuously varying electrical voltages. Analog video whether transmitted over cables, read from videotapes or broadcast, is subject to degradation due to noise, distortion and other electronic phenomena. Normal signal levels should be within 0.7-1 volt.
ANTI-ALIASING
The process of electronically reducing aliasing, especially letters and genlocked graphic elements.
APERTURE
An adjustable opening in a lens which, like the iris in the human eye, controls the amount of light entering a camera. The size of the aperture is controlled by the iris adjustment and is measured in f-stops. A smaller f-stop number corresponds to a larger opening which passes more light.
ASPECT RATIO
The ratio between the height and width of the TV picture on the screen. The aspect ratio for a standard TV or monitor is 4 to 3 (4:3). The HDTV video format has an aspect ratio of 16 to 9 (16:9).
AUDIO
The "other half" of any video production consisting of frequencies corresponding to a normally audible sound wave (20 Hz to 20,000 Hz), the "soundtrack" of a videotape.
AUDIO EDITING
Various portions of audio material are combined and recorded onto the videotape in one continuous form. For example, when a sound track is added to a videotape, various sounds such as background music, sound effects and voice narration, may be introduced in order to highlight particular movie scenes.
AUDIO LEVELS
Proper audio levels are crucial. If the audio level is too high when recording, overload of the input electronics will cause audio distortion. If audio levels are too low, the signal-to-noise ratio deteriorates. Audio levels are typically indicated either by mechanical VU-meters or electronic LED bar graph meters.
AUDIO MIXING
The blending of two or more audio signals to generate a combined signal which is often used for audio dub. During video processing, audio mixing may be used to insert narration or background music.
B-ROLL
Stock footage acquired for miscellaneous needs.
BACK LIGHT
1. A light source that illuminates a subject from behind, used to separate the subject from the background and give them depth and dimension. Back lights are often improperly applied or overlooked completely.
2. Also, a switch on some camcorders used to compensate exposure for situations where the brightest light is coming from behind the subject.
BETACAM SP
A superior performance version of Betacam. SP uses metal particle tape and a wider bandwidth recording system.
BLACK LEVEL
The voltage in a video signal which corresponds to black.
BNC CONNECTOR
A type of connector used on some VCRs, video and RF equipment providing twist-lock capability.
BORDER
The boundary between two merged video pictures, as created with chroma key or wipe effects.
CAMCORDER
Combination of camera and video tape recorder in one device. Camcorders permit easy and rapid photography and recording simultaneously. Camcorders are available in most home video formats: 8mm, Hi-8, VHS, VHS-C, S-VHS, etc.
CATV
Acronym for cable TV, derived from the older term, community antenna television.
CCTV (Closed Circuit TV)
A video system used in many commercial installations for specific purposes such as security, medical and educational.
CHARACTER GENERATOR
Device that electronically generates text which can be superimposed over a video signal. Text is usually entered via a keyboard, allowing selection of various fonts, sizes, colors, styles and background colors, then stored as multiple pages for retrieval.
CHROMA
The color information contained in a video signal, consisting of hue (phase angle) and saturation (amplitude) of the color subcarrier signal.
CHROMA NOISE
Noise which manifests itself in a video picture as colored snow.
CHROMA KEY
The process of overlaying one video signal over another by replacing a range of colors with the second signal. Typically, the first (foreground) picture is photographed with a person or object against a special, single-color background (the key-color). The second picture is inserted in place of the key-color. The most common example is in broadcast weather segments where pictures of weather maps are inserted "behind" the talent.
COAXIAL CABLE
The standard cable consisting of a central inner conductor and a cylindrical outer conductor. Used for many video connections, especially by CATV companies.
COLOR BARS
An electronically generated video pattern consisting of eight equal width colors, used to establish a proper color reference before recording and playback and for adjustment purposes.
COLOR CORRECTION
A process in which the coloring in a television image is altered or corrected by electronic means.
COLOR TEMPERATURE
A method for specifying the overall color of a light source, measured in degrees Kelvin (deg.K). Higher numbers indicate bluer light, lower numbers indicate a warmer light.
COLORIZATION
Special effect (also called paint) which colors a monochrome or color image with artificial colors.
COMPONENT VIDEO
Most home video signals consist of combined (composite) video signals, composed of luminance (brightness) information, chrominance (color) information and sync information. To get maximum video quality, professional equipment (Betacam and MII) and some consumer equipment (S-VHS and Hi-8) keep the video components separate. Component video comes in several varieties: RGB (red, green, blue), YUV (luminance, sync, and red/blue) and Y/C (luminance and chrominance), used by S-Video (S-VHS and Hi-8) systems.
COMPOSITE SYNC
A signal consisting of horizontal sync pulses, vertical sync pulses and equalizing pulses only.
COMPOSITE VIDEO
A video signal in which the luminance (brightness), chrominance (color), blanking pulses, sync pulses and color burst information have been combined using one of the coding standards. (NTSC, PAL, SECAM)
COMPRESSION
1. The process of electronically processing a video picture to make it use less storage or to allow more video to be sent down a transmission channel.
2. The process of removing picture data to decrease the size of a video image.
CONTRAST
1. The degree to which the various luminance values in a picture are mapped to very dark and very light values. A high-contrast picture is dominated by black and white and few values between. A low contrast picture has a lot of middle tones without many very dark or very light areas.
2. A control on a television or monitor which adjusts the white level of the picture.
CONTROL TRACK
The magnetized portion along the length of a videotape on which sync control information is placed. The control track contains a pulse for each video field and is used to synchronize the tape and the video signal.
CROSSFADE
The audio equivalent of the video dissolve where one sound track is gradually faded out while a second sound track simultaneously replaces the original one.
CROSSTALK
The interference between two audio or two video signals caused by unwanted stray signals. In video, crosstalk between input channels can be classified into two basic categories: luminance/sync crosstalk; and color (chroma*) crosstalk. When video crosstalk is too high, ghost images from one source appear over the other. In audio, signal leakage, typically between left and right channels or between different inputs, can be caused by poor grounding connections or improperly shielded cables.
DAT (Digital Audio Tape)
A consumer digital audio recording and playback system developed by Sony, with a signal quality capability surpassing that of the CD.
dB (Decibel)
A unit for expressing the ratio of two amounts of electric or acoustic signal power, used for measuring audio and video signals. Technically, this is equal to 20 times the common logarithm of the voltage or current ratio.
DECODE
To separate a composite video signal into its component parts.
DEFINITION
The aggregate of fine details available on-screen. The higher the image definition, the greater the number of details that can be discerned. During video recording and subsequent playback, several factors can conspire to cause a loss of definition. Among these are the limited frequency response of magnetic tapes and signal losses associated with electronic circuitry employed in the recording process. These losses occur because fine details appear in the highest frequency region of a video signal and this portion is usually the first casualty of signal degradation. Each additional generation of a videotape results in fewer and fewer fine details as losses are accumulated.
DEPTH OF FIELD
The range of objects in front of a camera lens which are in focus. Smaller f-stops provide greater depth of field, i.e., more of the scene, near to far, will be in focus.
DIGITAL
A method of representing data using binary numbers. An analog signal is converted to digital by the use of an analog-to-digital (A/D) converter chip by taking samples of the signal at a fixed time interval (sampling frequency). Assigning a binary number to these samples, this digital stream is then recorded onto magnetic tape. Upon playback, a digital-to-analog (D/A) converter chip reads the binary data and reconstructs the original analog signal. This process virtually eliminates generation loss as every digital-to-digital copy is theoretically an exact duplicate of the original allowing multi-generational dubs to be made without degradation. In actuality of course, digital systems are not perfect and specialized hardware/software is used to correct all but the most severe data loss. Digital signals are virtually immune to noise, distortion, crosstalk, and other quality problems. In addition, digitally based equipment often offers advantages in cost, features, performance and reliability when compared to analog equipment.
DISSOLVE
A process whereby one video signal is gradually faded out while a second image simultaneously replaces the original one.
DISTORTION
In video, distortion usually refers to changes in the luminance or chrominance portions of a signal. It may contort the picture and produce improper contrast, faulty luminance levels, twisted images, erroneous colors and snow. In audio, distortion refers to any undesired changes in the waveform of a signal caused by the introduction of spurious elements. The most common audio distortions are harmonic distortion, intermodulation distortion, crossover distortion, transient distortion and phase distortion.
DISTRIBUTION AMPLIFIER
A device which splits (distributes) one audio and/or video source to several audio/video device inputs. Typically, distribution amplifiers are used in duplication studios where many tape copies must be generated from one source or in multiple display setups where many monitors must carry the same picture, etc.
DOLBY(TM)
A compression/expansion (companding) noise reduction system developed by Ray Dolby, widely used in consumer, professional and broadcast audio applications. Signal-to-noise ratio improvement is accomplished by processing a signal before recording and reverse-processing the signal upon playback.
DROPOUT
A momentary partial or complete loss of picture and/or sound caused by such things as dust, dirt on the videotape or heads, crumpled videotape or flaws in the oxide layer of magnetic tape. Uncompensated dropout produces white or black streaks in the picture.
DSK (Downstream Keying)
An effect available in some special effects generators and video mixers in which one video signal is keyed on top of another video signal. The lightest portions of the DSK signal replace the source video leaving the dark areas showing the original video image. Optionally, the DSK signal can be inverted so the dark portions are keyed rather than the lightest portions allowing a solid color to be added to the keyed portions. The DSK input is most commonly a video camera or character generator. The DSK signal must be genlocked to the other signals.
DUB
A duplicate copy made from one recording medium to another.
DVE(TM) (Digital Video Effects)
These effects are found in special effects generators which employ digital signal processing to create two or three dimensional wipe effects. DVE generators are getting less expensive and the kind of effects they create getting more popular.
EDIT CONTROL
A connection on a VCR or camcorder which allows direct communication with external edit control devices. (e.g., LANC (Control-L) and NEW (Panasonic) 5-pin).
EDIT POINT
The location in a video where a production event occurs. (e.g., dissolve or wipe from one scene to another)
EDL (Edit Decision List)
A list of a video production's edit points. An EDL is a record of all original videotape scene location time references, corresponding to a production's transition events. EDLs are usually generated by computerized editing equipment and saved for later use and modification.
ENCODE
The process of combining analog or digital video signals, e.g., red, green and blue, into one composite signal.
ENHANCING
Improving a video image by boosting the high frequency content lost during recording. There are several types of enhancement. The most common accentuates edges between light and dark images.
FADE
The act of dissolving a video picture to either a color, pattern or titles. Fading a video image is often used as an artistic tool in video productions, most commonly seen as a fade to black. In audio, there is a decrease in the sound level until it is no longer audible. Audio fading is often used in conjunction with video fading causing the sound and image to fade simultaneously.
FIELD
One-half of a complete television picture consisting of one complete vertical scan of the video image containing 262.5 line for NTSC and 312.5 lines for PAL. Two fields make up a complete television picture frame.
FILL LIGHT
Fill lights, commonly referred to as "scoops," provide a soft-edged field of light used to provide additional subject illumination to reduce harsh shadows or areas not highlighted by the key light.
FILM CHAIN
Projectors, multiplexors and cameras, connected for the purpose of transferring film to video.
FLICKER
A strobing picture artifact, similar to an old-time movie effect, mainly related to vertical syncs and video field display rates. Some flicker normally exists due to interlacing, but is more apparent in 50 Hz systems (PAL) and when converting film (24 fps) to video (30 fps). Flicker may also be a problem when static computer images are transferred to video.
FLIP
Special effect in which the picture is either horizontally or vertically reversed.
FM (FREQUENCY MODULATION)
Frequency modulation is a process used for radio (FM broadcast) and television audio transmission and videotape recording. A low frequency (program) signal modulates (changes) the frequency of a high frequency RF* carrier signal (causing it to deviate from its nominal base frequency). The original program signal is recovered (demodulated) at the receiver. This system is extensively used in broadcast radio transmission because it is less prone to signal interference and retains most of the original signal quality. In video, FM is used in order to record high quality signals on videotape.
FORMAT (Videotape)
A variety of formats are used to record video. They vary by tape width: (8mm, 1/2 inch, 3/4 inch, 1 inch), signal form: (composite, Y/C, component), data storage type (analog or digital) and signal standard (PAL, NTSC, SECAM).
FRAME
A complete video image consisting of 2 fields. Also used to describe the total visible area of a video image. There are 30 frames per second on video tape.
FRAME SYNCHRONIZER
A digital electronic device which synchronizes two or more video signals. The frame synchronizer uses one of its inputs as a reference and genlocks the other video signals to the reference's sync and color burst signals. By delaying the other signals so that each line and field* starts at the same time, two or more video images can be blended, wiped and otherwise processed together.
FREEZE (Frame)
Special effect in which the picture is held as a still image. It is possible to freeze either one field or a whole frame. Freezing one field provides a more stable image if the subject is moving, however, the resolution of the video image is half that of a full frame freeze. Digital freeze frame is one special effect that could be created with a special effects generator or a TBC.
GENERATION
The number of duplication steps between an original recording and a given copy. A second generation duplicate is a copy of the original master and a third generation duplicate is a copy of a copy of the original master, etc.
GENERATION LOSS
When an analog master videotape is duplicated, the second-generation copy is usually inferior in some way to the master. This degradation appears as loss of detail, improper colors, sync loss, etc. Limited frequency response of audio/video magnetic tape and imperfections in electronic circuitry are the main causes of generation loss. Higher performance formats (such as 1-inch) exhibit much less generation loss than more basic formats. Digital formats make generation loss negligible because each copy is essentially an exact duplicate of the original. Video enhancing equipment can minimize generation loss. Some video processors pre-enhance the video signal to overcome generation loss.
GENLOCK
A method of synchronization involving the generation of a video signal sync-locked with another signal. Because they are synchronized, a genlocked signal can be mixed with the original signal, allowing dissolves, wipes, and other transition effects. Genlock and frame synchronization differ in that genlock is the generation of a new signal synchronized to a video signal that is already present while frame synchronization takes two already-generated signals and synchronizes them. Genlocking two VCRs requires the use of a time base corrector (TBC).
GHOSTING
A weak, secondary, ghost-like duplicate video image in a video signal caused by the undesired mixing of the primary signal and a delayed version of the same signal.
HARMONIC DISTORTION
When any signal is passed through an electronic circuit, the signal may be changed in many ways. In video, the image may become blurred, noisy or contain shadows. In audio, odd harmonics (third, fifth, etc.) produce harsh and unpleasant sounding audio.
HDTV (High Definition Television)
A television format for producing high resolution video. Typically, these systems provide about 1125 lines of horizontal resolution (compared to 525 for NTSC and 625 for PAL) and an aspect ratio of 16:9, for image quality approaching 35mm film photography.
HI-8
An improved version of the 8mm tape format capable of recording better picture resolution (definition). A higher-density tape is required which provides a wider luminance bandwidth, resulting in sharper picture quality (over 400 horizontal lines vs. 240 for standard 8mm) and improved signal-to-noise ratio. Camcorders using this format are very small, light and provide a picture quality similar to S-VHS.
HI-FI (High Fidelity)
Most commonly used to refer to the high quality audio tracks recorded by many VCRs. These tracks provide audio quality approaching that of a CD. However, because they are combined with the video signal before recording, audio dubs using them are impossible without re-recording the video.
HISS
The most common audible noise component in audio recording, stemming from a combination of circuit and tape noise. Several noise reduction systems are available, such as Dolby, DBX, DNR (Dynamic Noise Reduction), DNL (Dynamic Noise Limiter), to help alleviate such problems.
HORIZONTAL RESOLUTION
Rating of the fine detail (definition) of a TV picture, measured in scan lines. The more lines, the higher the resolution and the better the picture. A standard VHS format VCR produces 240 lines of horizontal resolution, while over 400 lines are possible with S-VHS, S-VHS-C, and Hi-8 camcorders.
HORIZONTAL SYNC
The sync pulse signal produced at the beginning of each video scan line which keeps a video monitor's horizontal scan rate in step with the transmission of each new line.
HUE
Often used synonymously with the term tint. It is the dominant wavelength which distinguishes a color such as red, yellow, etc. Most commonly, video hue is influenced by a camera's white balance and scene lighting. Video color processors are the main tools used to adjust and correct hue problems.
IMAGE STABILIZATION
A camcorder feature which takes out minor picture shakiness, either optically or electronically.
INSERT EDITING
Camcorder/VCR feature which allows a user to insert new audio/video segments into the middle of a previously recorded tape. Some camcorders insert both audio and video simultaneously; others can insert audio and/or video separately.
INTERLACING
A system developed for television which divides each video frame into two fields. This is done by first drawing one field consisting of an image's odd scan lines (1, 3, 5...525) and then drawing the remaining even scan lines (2, 4, 6...), interweaving both fields. Interlacing reduces the perception of screen flicker. Interlacing can cause annoying effects with images such as computer generated text and graphics when transferred to video.
JITTER
Small, rapid variations in a waveform or image due most often to mechanical disturbances.
JPEG (Joint Photographic Experts Group)
JPEG is a digital compression standard for still video images that allows the image to occupy less memory or disk space. Like the MPEG standard, it includes options for trading off between storage space and image quality.
KEY LIGHT
The term used to describe a subject's main source of illumination. When shooting outdoors, the key light is the sun.
LAVALIERE MICROPHONE
Small microphone worn around the neck or clipped to clothing.
LCD (Liquid Crystal Display)
A screen for displaying text/graphics based on a technology called liquid crystal, where minute currents change the reflectiveness or transparency of the screen. The advantages of LCD screens are: very small power consumption (can be easily battery driven) and low price of mass produced units. Its disadvantages presently include narrow viewing angle, somewhat slower response time, invisibility in the dark unless the display is back-lit, difficulties displaying true colors and resolution limitations.
LINEAR EDITING
Editing using media like tape, in which material must be accessed in order (e.g., to access scene 5 from the beginning of the tape, one must proceed from scene 1 through scene 4).
LOOPING
A term used to describe the chaining of a video signal through several video devices (distribution amplifiers, VCRs, monitors, etc.). A VCR may be hooked up to a distribution amplifier which is supplied with a video input connector and a loop output connector. When a signal is fed to the distribution amplifier, it is also fed unprocessed to the loop output connector (parallel connection) on the distribution amplifier. In turn, the same signal is fed to another device which is attached to the first one and so on. Thus a very large number of VCRs or other video devices can be looped together for multiple processing.
LTC (Longitudinal Time Code)
SMPTE (Society of Motion Picture and Television Engineers) time code standard usually recorded onto the linear audio track of a VCR or audio tape machine.
LUMINANCE
The degree of brightness (black and white portion of the video signal) at any given point in the video image. A video signal is comprised of luminance, chrominance (color information) and sync. If luminance is high, the picture is bright and if low the picture is dark. Changing the chrominance does not affect the brightness of the picture.
LUMINANCE NOISE
Noise which manifests itself in a video picture as white snow.
LUX
A measurement of light intensity, which is used in photography for the comparison of camera sensitivities. (1 Footcandle = 10.76 Lux)
MII
Portable, professional video component camera/recorder format, utilizing 1/2" metal particle videotape.
MATRIX SWITCHER
A device which uses an array of electronic switches to route a number of audio/video signals to one or more outputs in almost any combination. Production quality matrix switchers perform vertical interval switching for interference free switching.
MOIR
A distracting wavy effect produced when converging lines in a video image are nearly parallel to a monitor's scanning lines.
MONITOR
A display that gets its signal directly from a camera or VCR, as opposed to a television, which relies on RF signals, such as those from cable television or broadcast. A monitor uses composite (RCA-style), S-Video (Y/C) and/or BNC video jacks.
MPEG (Motion/JPEG)
MPEG is a digital compression standard for moving video images that allows the images to occupy less memory or disk space. Like the JPEG standard, it includes options for trading off between storage space and image quality.
MULTIMEDIA
A somewhat ambiguous term that describes the ability to combine audio, video and other information with graphics, control, storage and other features of computer-based systems. Applications include presentation, editing, interactive learning, games and conferencing.
MULTI-STANDARD
A monitor which synchronizes to different video signal standards such as NTSC and PAL.
NEGATIVE EFFECT
Special effect in which either blacks and whites are reversed or colors are inverted.
NOISE
A general term used in electronics to indicate any unwanted electrical signal, unrelated to the original signal. Video noise is generally manifested as snow, graininess, ghost images or picture static induced by external sources such as the national power-line grid, electric motors, fluorescent lamps, etc. In audio, noise is generally manifested as hiss and static.
NOISE REDUCTION
An electronic process used to reduce noise levels in audio and video. In video, the most effective noise reduction is accomplished by digitizing the video signal and carrying out a computerized pixel by pixel analysis of the data. In audio, the most effective systems employ an encode/decode scheme, performed before and after recording, such as the Dolby audio noise reduction system. Noise reduction can be performed on an existing audio signal using systems such as DNR (dynamic noise reduction) but are less effective because they also affect the audio signal.
NONLINEAR EDITING
The process of editing using rapid retrieval (random access) computer controlled media such as hard disks, CD-ROMs and laser discs. Its main advantages are: a.) allows you to reorganize clips or make changes to sections without having to redo the entire production; and b.) very fast random access to any point on the hard disk (typically 20-40 ms)
NTSC (National Television Standards Committee)
Standard of color TV broadcasting used mainly in the United States, Canada, Mexico and Japan, featuring 525 lines per frame and 30 frames per second.
OVERLAY
Keyed insertion of one image into another. Overlay is used for example, to superimpose computer generated text on a video image, for titling purposes. In video, the overlay procedure requires synchronized sources for proper operation.
OVERSCAN
Video images generally exceed the size of the physical screen. The edge of the picture may or may not be displayed, to allow variations in television sets. The extra area is called the overscan area. Video productions are planned so critical action only occurs in the center safe title area. Professional monitors are capable of displaying the entire video image including the overscan area.
PAL (Phase Alternate Line)
The European color TV broadcasting standard featuring 625 lines per frame and 25 frames per second.
PEDESTAL
The pedestal is a small DC voltage step within the video signal indicating a picture's black-level and is used as the reference in a standard video signal for white level and all gray levels.
PICTURE SHARPNESS
The fine details in a video picture. A picture appears sharp when it contains fine details and has good contrast. Picture sharpness is easily lost during the recording/playback process. Advanced video enhancement equipment is used to improve picture sharpness, especially contrast, and can precompensate for potential losses which might alter an image during processing.
PIP (Picture In Picture)
A digital special effect in which one video image is inserted within another allowing several images to share a single screen.
PLAYBACK
The process whereby a videotape is displayed on a monitor. During playback, use of a video processor can be used to alter, enhance, correct or restore a signal.
POST-PRODUCTION
All production work done after the raw video footage and audio elements have been captured. Editing, titling, special effects insertion, image enhancement, audio mixing and other production work is done during post-production.
POSTERIZATION
Special effect in which the picture is reduced to a small number of colors or luminance levels removing any fine gradations of color and brightness resulting in an oil painting effect.
PRIMARY COLORS
The basic colors used in TV and video systems of red, green and blue.
QUANTIZATION RESOLUTION
The accuracy of measuring an analog signal and representing its strength with numbers. A two-bit resolution describes something by 4 levels, a three-bit resolution, 8 levels.
QUANTIZATION
The process of measuring an analog signal and assigning numerical levels to it.
RCA CONNECTOR
A type of connector used on all consumer VCRs and camcorders to carry the standard composite video and audio signals.
REAL TIME COUNTER
A display showing hours-minutes-seconds of tape that has been recorded (elapsed time), or how much tape remains.
RESOLUTION
A measure of the ability to reproduce detail. Generally, referred to as horizontal resolution and evaluated by establishing the number of horizontal lines which are clearly discernible on a test pattern. Resolution specifications are not very well standardized, especially as stated in connection with monitors. Using the rule of thumb of 80 lines per MHz of bandwidth, VHS and 8mm typically achieves 240 lines of resolution, S-VHS and Hi-8 achieve 400, broadcast achieves 600.
RF (Radio Frequency)
A term used to describe the radio signal band of the electromagnetic spectrum (about 3 MHz to 300 GHz). RF connectors, such as those used for the cable TV or antenna inputs on a monitor, carry modulated television signals.
RGB (Red/Green/Blue)
The basic components of a color video signal. Using a color encoder, in conjunction with sync information, a complete composite video signal comprising luminance, chrominance and sync can be generated from RGB.
RS-232/RS-422
Computer communication standards used in video for the control of certain video equipment. Computer controlled VCRs, edit controllers, switchers and other studio equipment can commonly be found in professional video studios. Successfully linking two devices, at the very least, requires that they use the same communication protocol.
SAFE TITLE AREA
Generally, the center 80% of the entire overscan video image area or that area which will display legible titles regardless of how a TV monitor is adjusted.
SECAM (Sequential Couleur A'memorie)
The video standard used in some European and surrounding countries. In countries using the SECAM standard, most video production is done using PAL and converted to SECAM prior to transmission.
SERIAL PORT
A computer l/O (input/output) port through which the computer communicates with the external world. The standard serial port uses RS-232 or RS-422 protocols.
SEPIA TONE
A process used in photography to generate a brownish tone in pictures giving them an "antique" appearance. The same idea has been electronically adapted for video production where a black and white image can be colored in sepia.
SHOTGUN MICROPHONE
Long, highly directional microphone designed to pick up sounds directly in front of the microphone, rejecting sound from other directions. Named for its appearance.
SIGNAL-TO-NOISE RATIO (S/N)
The ratio in decibels (dB), of an audio or video signal, between the signal's maximum peak-to-peak signal voltage and the measured voltage of what remains when the signal is removed, (i.e., the ratio of the signal to that of the noise). In video, the higher the ratio, the less snow is visible. In audio, the higher the ratio, the cleaner the sound. Audio s/n ratios vary tremendously from compact discs/camcorder AFM Hi-Fi* tracks (typically 90 dB) to VCR linear tracks (typically 40 dB).
SMPTE
Society of Motion Picture and Television Engineers. Also refers to the time-coding technique used by most professionals. Pronounced Simp-Tee.
SNOW
A general term used to describe interference in a video image. It manifests as random colored or black and white dots.
SOLARIZATION
Special effect in which the lightest and darkest values of a picture are made dark while the middle tones become light.
SPECIAL EFFECTS
Artistic effects added to a video production in order to enhance the production by creating drama, enhancing the mood or furthering the story. Special effects may vary from the limited addition of patterns or the mixing of several video images together, to sophisticated digital effects such as picture compression, page flipping and three-dimensional effects. Special effects are usually created using SEGs.
SPLIT SCREEN
An electronic process which allows the viewing of two video images, side by side or above and below, on-screen simultaneously.
STROBE
Special effect in which a frame is periodically held for a finite time until another frame is held.
SUPERIMPOSE
To place in front of video, e.g., placing text over a video signal.
S-VHS (Super VHS)
An improved version of the VHS tape format capable of recording better picture resolution (definition). A higher-density tape is required which provides a wider luminance bandwidth, resulting in sharper picture quality (> 400 horizontal lines vs. 240 for standard VHS) and improved signal-to-noise ratio. Because the equipment is usually smaller and lighter than 3/4" equipment, it is ideally suited for ENG/EFP applications.
S-VHS-C (Super VHS-C)
An improved version of the VHS-C tape format capable of recording better picture resolution (definition).
S-Video (Separated Video)
Describes a system of plugs and jacks used to interconnect camcorders, VCRs and TV monitors, which keeps the chrominance (color) and luminance (brightness) information separate. Also called Y/C connectors (luminance/chrominance), this system greatly improves picture quality by keeping any signal interaction (degradation) to a minimum.
SWITCHER
General term for a device used to select different signals (audio, video or RF) from various sources.
SYNC (Synchronization)
A term used in electronics to describe the precise alignment of two signals or functions. In video, sync is an essential element for maintaining the proper clocking of video signals. The sync signal is used by a monitor to know where and when to draw the on-screen video image.
TALENT
A term used to refer to on-camera subjects in a video production. Not to be confused with CREATIVE TALENT: Producers; director; casting; and others.
TALLY LAMP
A signal lamp or LED installed on a video camera which informs performers and crew members that the camera is currently live.
TBC (Time Base Corrector)
A device used to rectify any problems with a video signal's sync pulses by generating a new clean time base and synchronizing any other incoming video to this reference.
TELECINE
Telecine is a term used to describe a device used to convert film to video. In advanced telecine machines, the movie film is digitally sampled and converted to video, frame by frame in real-time. Frame rate is the biggest problem encountered in film-to-video conversion. Movie film has a frame rate of 18, 24 or 30 fps (frames per second) contrasting with the 30 and 25 fps video frame rates of NTSC and PAL respectively.
TELE-PROMPTER
A device for displaying large, readable text on a partially transparent screen for video production. The tele-prompter uses a monitor mounted under the camera lens, facing up, and a mirrored glass which reflects the monitor's image toward the talent. Since the camera shoots through the mirrored glass and the mirrored glass is transparent to the camera, the talent can look directly into the camera lens as they read the script from the glass.
TERMINATION SWITCH
A switch that connects and disconnects a load resistance to a video input, used to terminate the line. In order for a video signal to be correctly transmitted without loss, proper end of line impedance is essential. A 50 or 75 ohm resistor is usually employed to accomplish this. When the termination switch is off, the unterminated video signal is looped to the next device where the signal can be transmitted in parallel. The final device in the chain must be terminated using the termination switch.
TEST PATTERN
A chart with special patterns, placed in front of a television camera to generate a known reference signal that can be used to adjust the camera and all the equipment downstream from the camera.
TIME CODE
A digital code number recorded onto a videotape for editing purposes. When decoded, the time code identifies every frame of a videotape using digits reading hours:minutes:seconds and frames. Each individual video frame is assigned a unique address, a must for accurate editing. The three time code systems used for video are VITC, LTC and RC (consumer).
TITLING
The addition of text, symbols and graphic elements to a video image. Titles may be added to a video scene during shooting or in post-production. Sophisticated titling devices allow the user to prepare text and graphics in various sizes, fonts and colors to be triggered later, one-by-one, at appropriate places within a production. Many video cameras* include basic titlers or permit externally-generated titles to be mixed with the video image during shooting.
TRACKING
The angle and speed at which the tape passes the video heads. Due to small differences in head-to-tape alignment between VCRs, it is sometimes necessary to adjust the tracking control on a VCR when playing a tape recorded on another deck.
UNDERSCAN
The opposite of overscan. In underscan, a video or computer image is reduced so that all four edges are visible on-screen, leaving it surrounded by black borders. Underscan is used to show what is happening in the blanking period and at the beginning and end of scan lines and frames. Underscanning can uncover latent image problems for identification and correction.
VHS (Video Home System)
Consumer videocassette record/playback tape format using half-inch wide magnetic tape. The most common home VCR format in the U.S.
VHS Hi-Fi
An improved stereo audio recording/playback system found on some camcorders and VCRs. Because the audio tracks are mixed and recorded with the video signal, audio only dubbing of these tracks is not possible.
VHS-C (VHS-Compact)
A miniature version of the VHS tape format utilizing smaller cassettes that may also be played on standard VHS machines by using an adapter cartridge.
VIDEO BANDWIDTH
The range between the lowest and highest signal frequency of a given video signal. In general, the higher the video bandwidth, the better the quality of the picture. Video bandwidths used in studio work typically vary between 3 and 12 MHz. Consumer VCRs are generally capable of 3-5.5 MHz.
VIDEO CAMERA
A camera which contains an electronic image sensor rather than photographic film. The lens focuses an image on an electronic tube or CCD chip. A camera has electronic circuitry which generates color and sync pulses. Most portable consumer cameras are equipped with a full complement of audio circuitry, e.g., microphone, audio amplifier and additional audio electronics. In order to obtain better quality images, a professional camera has three tubes or a triple CCD system, one for each basic color. Most professional cameras have a genlock input, which allows the camera to be synchronized to an external source. Some cameras also include basic character generators for titling* purposes.
VIDEO EDITING
A procedure for combining selected portions of video footage in order to create a new, combined version. A variety of editing consoles are available. During video editing, special effects such as wipes, dissolves, inserts, etc. can be added. Professional editing is done using time code recorded on every frame of the magnetic tape allowing single frame accuracy. Audio editing is often carried out simultaneously with video editing.
VIDEO GAIN
The nominal composite video signal level is 1 volt. At this level, a fully saturated image is transmitted and boosting the signal offers no advantage. Most video equipment is designed to output the same 1-volt level video signal. In cases where the signal level has been reduced, such as after a long cable run, an amplifier with video gain may be employed to restore the proper level.
VIDEO MIXER
A device used to combine video signals from two or more sources. Inputs are synchronized, then mixed along with various special effects patterns and shapes. A video mixer usually generates sync signals allowing genlocking of additional video sources to the first source.
VIDEO PRINTER
A special device used to capture a single frame of video to create a hard copy print.
VIDEO WALL
A large array of several monitors, placed close to one another in the shape of a video screen or "wall." Each monitor is fed only part of the original video image by using a video-wall generating unit. This device is a digitally-based processor which converts the original analog video signal to digital, rescans, resamples and generates several individual analog video outputs for driving each array monitor separately. When viewed from a distance, the effect can be very dramatic.
VITC (Vertical Interval Time Code)
A popular method for recording time code onto videotape. A time code address for each video frame is inserted in the vertical interval (the vertical blanking retrace period) of the video signal, where it is invisible on-screen yet easily retrieved, even when a helical scanning VCR is in pause mode. The most common form of VITC is SMPTE-VITC.
WHITE BALANCE
An electronic process used in camcorders and video cameras to calibrate the picture for accurate color display in different lighting conditions. White balancing should be performed prior to any recording, typically by pointing the camera at a white object for reference.
WIPE
Special effect in which two pictures from different video sources are displayed on one screen. Special effects generators provide numerous wipe patterns varying from simple horizontal and vertical wipes to multi-shaped, multi-colored arrangements.
X-Y STEREO MIKING
Mike setup for stereo using two cardioids crossed, one aiming left, the other right, their heads almost touching.
Y/C (Luminance and Chrominance)
A term used to describe the separation of video signal components used in systems such as Hi-8 and S-VHS. Generically called S-Video.
ZOOM LENS
A lens which can "zoom in" or "zoom out" to give a closer-looking picture or a wider angle of view.
ZEBRA AFFECT
When alternating stripes of white and black signals appear on a monitor.
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