Grass Valley Dictionary

Dictionary of Technical Terms - S

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A full-featured GVG video tape editing system that runs on the Silicon Graphics Indy™ workstation.

Safe title area (safe action area)

An area in the center of the television screen where it is considered safe to place a title key or other graphic so that none of it will get cut off at the outer edges by a TV receiver. The safe action area is slightly larger than the safe title area and is the area within which action should be confined so as to ensure that it will be visible on most television sets.

The sending of a group of commands at the same time.

sample and hold

A circuit that takes a sample of an input voltage and holds or maintains that voltage at its output for a period of time.

Process by which an analog signal is measured, often millions of times per second for video, in order to convert the analog signal to digital.

sampling frequency

The number of discrete sample measurements made in a given period of time. Often expressed in megahertz for video.

1. An orbiting space vehicle containing a set of transponders that retransmit television broadcast signals back to earth receivers. 2. A TV station licensed to rebroadcast the programming of a parent station.

satellite auxiliary bus control panel

Relating to video switchers, a standalone auxiliary bus control panel.

satellite downlink

The communications path from a satellite to its ground station.

satellite uplink

The communications path from a ground station to its satellite.

saturation (chroma, chroma gain)

1. The intensity of the colors in the active picture. The voltage levels of the colors. The degree by which the eye perceives a color as departing from a gray or white scale of the same brightness. A 100% saturated color does not contain any white; adding white reduces saturation. In NTSC and PAL video signals, the color saturation at any particular instant in the picture is conveyed by the corresponding instantaneous amplitude of the active video subcarrier. 2. The point on the operational curve of an amplifier at which an increase in input amplitude will no longer result in an increase in amplitude at the output.

Start of active video. A synchronizing signal used in component digital video.

SC/H phase (subcarrier to horizontal phase)

In NTSC video, the phase relationship of the subcarrier to the leading edge of horizontal sync. SC/H phase is correct when the zero crossing of subcarrier is aligned with the 50% point of the leading edge of sync. In PAL video, the SC/H phase is defined as the phase of the EU component of the color burst extrapolated to the half amplitude point of the leading edge of synchronizing pulse of line 1 of field 1.

SC/H phase error

An incorrect phase relationship of the subcarrier to the leading edge of horizontal sync.

SC/H phased (timed)

The time relationship of the subcarrier to (the leading edge of) horizontal sync is correct. See SC/H phase.

One sweep of the target area in a camera tube or of the screen in a picture tube.

See timing scatter.

A diagram of the electrical scheme of a circuit with components represented by graphic symbols.

Slang, short for oscilloscope (waveform monitor) or vectorscope, which are electronic devices used to display and measure the television signal.

SC phase stability

The equipment in question is able to maintain subcarrier phase with-in specifications.

1. To transpose or invert digital data according to a prearranged scheme in order to break up the low-frequency patterns associated with serial digital signals. 2. The digital signal is shuffled to produce a better spectral distribution.

(1) An S-shaped frequency-response curve showing how the output of a frequency-modulation detector or circuit varies with frequency. (2) In GVG switchers and digital picture manipulators, a type of motion path between key frames where the graph of displacement versus time is shaped like an S; in other words, movement between key frames takes place at a variable speed.

Sequential couleur avec memoire (sequential color with memory). A color television system with 625 lines per frame and 50 fields per second developed by France and the U.S.S.R. Color difference information is transmitted sequentially on alternate lines as an FM signal.

An editor command that enables the user to search for and find a particular event in the edit decision list.

An insert key effect in which the key video signal serves as both the key source and fill.

The ability of a memory system to link several learned effects together and replay them based on timing information provided by the operator.

A GVG trademarked E-MEM(R) function that enables E-MEM(R) registers to be recalled automatically in a pre-programmed sequence.

sequential assembly

In video editing, a sequential method of auto assembly. The computerized editing system records all edits listed in the edit decision list in order from first to last, requesting source tapes as they are need-ed. Also called A-mode assembly. See also auto assembly.

Time-sequential transmission of data along a single wire. Analogous to a railroad train, where each car (data bit) follows the other in single file.

serial control panel

A control panel separate from the switcher (for example, a routing switcher) that communicates with the switcher via a serial connection.

1. Digital information that is transmitted in serial form. Often used informally to refer to serial digital television signals.

serial interface

A digital communications interface in which data is transmitted and received sequentially along a single wire or pair of wires. Common serial interface standards are RS232 and RS422.

A device that converts parallel digital information to serial.

serial video processing

A video mixing architecture where a series of video multipliers, each combining two video signals, is cascaded or arranged in a serial fashion. The output of one multiplier feeds the input of the next, and so on, permitting effects to be built up, one on top of the other.

serrations (vertical serrations)

A series of equally-spaced pulses within a pulse signal. For example, the vertical sync pulse is serrated in order to keep the horizontal sweep circuits locked during the vertical-sync-pulse interval.

An editor command meaning to enter an in-edit point.

A method of video editing using precise in and out point selection as opposed to on-the-fly editing.

An editor command meaning to enter an out-edit point.

setup (black reference, black level)

1. The specified base of the active picture signal which is at reference black level. Called setup because it is placed 7.5 IRE units above blanking (zero IRE) in NTSC video. 2. The basic operating configuration of a system.

To adjust the contrast and color levels of a camera.

A chroma key that retains the shadows cast by the foreground object.

An digital electrical device similar to a potentiometer in function. The turns of a shaft, typically connected to a knob, are read and encoded into digital data.

shaping, shaped video

Shaped video is video that has already been multiplied by a key signal, usually resulting in a video shape that appears over a black matte. Typically, shaped video is the output of a character or graphics generator, together with a matching key signal. Both signals have ``soft'' anti-aliased edges. The two signals may be used in the keyer of a production switcher, where the key signal cuts a hole in the background and the shaped video fills the hole to create an anti-aliased key.

short time linear distortion

In video, an unwarranted change in amplitude or phase that occurs in a short time frame (0.1 to 1 microsecond). The resulting TV picture will have dulled luminance transitions (fuzzy vertical lines) and color bleeding of areas adjacent to the vertical lines.

A box that mounts on a video camera and includes several buttons that activate various preset automatic zoom speeds and zoom positions.

In videotape machines, a high-speed tape-running mode that permits fast cuing or rewinding of the tape.

A waveform used to convey information from one point to another.

signal conditioning

The processing of a signal so as to make it compatible with a given device, including pulse shaping, pulse clipping, etc.

signal generator

A test oscillator that can be adjusted to provide a test signal at some desired frequency, voltage, modulation, and waveform.

signal processing

See signal conditioning.

signal to noise ratio (SNR, S/N)

Expressed in decibels, the signal to noise ratio relates how much stronger a signal is than the background noise.

A GVG trademarked Borderline(R) generator for the Model 200 switcher that can create borders and shadows that are up to 8 lines wide and that can be moved using the joystick positioner.

A periodic wave in which the waveshape is proportional to the sine of the time variable.

single channel mode

In GVG digital picture manipulators, a mode in which the panel is delegated to only one channel.

An unbalanced circuit where one side of the circuit or transmission line is grounded. See also balanced and unbalanced.

single-mode fiber

An optical glass fiber that consists of a core of very small diameter (usually 2-10 microns) and a cladding approximately 20 times the thickness of the core. Such fibers are normally used only with laser sources because of their very small acceptance cone. Since the cone diameter approaches the wavelength of the source, only a single mode is propagated.

1. A digital picture manipulator effect in which the picture is slanted along its horizontal or vertical axis. 2. Curve at the top of the picture resulting from improper VTR tape tension.

skewed key frame

In digital picture manipulators, the condition when a key frame in one channel does not line up with a key frame in another channel with respect to time.

In fiber optics, a transmitted ray that never intersects the longitudinal axis of the fiber while being transmitted.

Component in a system that does not act independently, but only under the control of another component.

Controlling port for subordinate equipment.

slave sync generator

A sync generator that receives a reference signal-typically color black or GVG's encoded subcarrier-from the master sync generator and produces all appropriate sync pulses. Slave generators normally feed each major area of the plant, such as videotape machines, cameras, switchers, etc.

The maximum rate of change of the output voltage of an amplifier operated within its linear region.

A video effect in which a picture slides across the monitor from one screen position to another.

A multiplexed analog component video standard proposed for studio intra-connection by the SMPTE working group on Component Analog Video Standards. The S-MAC system uses time compression and time domain multiplexing techniques to convey Y, Cr, Cb video signals.

Switched multimegabit data service.

A picture condition in which objects appear to be extended horizontally beyond their normal boundaries in a blurred or "smeared" manner.

Society of Motion Picture and Television Engineers. A professional organization that sets standards for American television. An informal name for a color difference video format that uses a variation of the Y, R-Y, & B-Y signal set.

SMPTE 125M (was RP-125)

The SMPTE recommended practice for a bit parallel digital interface for component video signals. SMPTE 125M defines the parameters required to generate and distribute component video signals on a parallel interface.

The SMPTE recommended practice for a bit parallel digital interface for composite video signals. SMPTE 244M defines the parameters required to generate and distribute composite video signals on a parallel interface.

The SMPTE recommended practice for 525 line serial digital component and composite interfaces.

SMPTE time code

Time code that conforms to SMPTE standards. It consists of an eight-digit number specifying hours: minutes: seconds: frames. Each number identifies one frame on a videotape. SMPTE time code may be of either the drop-frame or non-drop frame type. In GVG editors, the SMPTE time code mode enables the editor to read either drop-frame or non-drop frame code from tape and perform calculations for either type (also called mixed time code).

Surface mount technology.

Systems network architecture.

A frozen picture of the control settings of a production switcher or digital picture manipulator at a given point in time.

Signal-to-noise ratio. The SNR relates how much stronger a signal is than the background noise. Usually expressed in decibels (dB).

Electronic circuit that suppresses high frequencies.

soft black clip

Stops the luminance video going below a predetermined level.

A wipe pattern border that is mixed on the edges to give a graduated effect.

A pattern edge between two video signals in which the signals are mixed together for a graduated transition effect.

soft panel, soft knobs, soft controls

A hardware control panel whose functions are defined by software and subject to change depending upon which menu selections the operator has made.

A Grass Valley Group software-controlled feature set that may include E-MEM registers, standard programming, general purpose interface programming, and service diagnostics.

soft white clip

Stops the luminance video from going above a predetermined level.

A digital picture manipulator effect in which the luminance levels are reversed, resulting in a picture that looks like a photographic negative.

Synchronous optical network standard. A telecommunications standard.

1. Equipment that produces video, such as cameras, tape recorders, graphics and character generators. 2. In digital picture manipulators, the origin of picture information applied to the input of a digital effects processor. May be consist of a video component and sometimes a key component.

source identification

A brief message, keyed into video, that defines the originator or point of origin of the signal. Often consists of call letters and city of origin.

In digital picture manipulators, the axes of the video image on the monitor screen.

source synchronizing generator

A synchronizing pulse generator used to drive a specific piece of source equipment. It is referenced to a master reference synchronizing generator.

source terminated

A circuit whose output is already terminated for correct impedance matching with standard cable.

source timing module (STM)

Similar to a slave sync generator but occupies only a single module, typically for use in a distribution amplifier tray. Outputs a limited set of synchronization pulses that may be retimed relative to the locking master sync generator.

spectral bandwidth

In telecommunications, the spectral bandwidth for single peak devices is the difference between the wavelengths at which the radiant intensity is 50% (or 3dB) down from the maximum value.

See sync pulse generator.

To rotate a video image.

A curve shape produced on a computer or video device by connecting dots or points at various intervals along the curve. In digital picture manipulators, each key frame becomes a point on a curve and the user can control how straight or curved the path of the transformed image is as it travels through the key frame points.

An edit in which the audio in-edit point is different from the corresponding in-edit point of video or another audio channel.

Horizontal, vertical, or diagonal images. Split field EBU bars are an example.

A video switcher key mode in which one key bus button selects the hole cutter and a different key bus button selects the fill video. Also called key split or key breakaway.

A video effect in which two scenes are on screen at the same time, separated by a wipe pattern.

A highlight effect produced by superimposing a full-strength video signal shaped by a wipe pattern over an attenuated (darkened) signal from the same video source.

spurious signal

Any portion of the signal that is not part of the fundamental video signal. Spurious signals include transients, noise, and hum.

A square or rectangular-shaped periodic wave that alternately assumes two fixed values for equal lengths of time, the transition being negligible in comparison with the duration of each fixed value.

A digital picture manipulator effect where the picture is compressed (made smaller).

Compress an edit decision list.

Applying an s-shaped transfer function to a keyer to avoid high frequency keying artifacts.

Service switching point.

A trail effect in which random pixels turn off, creating a blinking or starry appearance.

The identification letters of a broadcast station.

The present condition of a device.

A condition in which circuit values remain essentially constant, occurring after all initial transients or fluctuating conditions have settled down.

A digital picture manipulator term meaning to advance a key frame effect one video frame or field at a time.

step index fiber

An optical fiber that has a core and a cladding with an abrupt change in the refraction index at the core-cladding interface. The index of the cladding is usually less than that of the core to permit total internal reflection.

Device for storage of specific frames of video.

Source timing module.

To record SMPTE time code onto a tape.

A GVG trademarked name for a soft panel and display.

Shared tenant services.

A room designed for recording or broadcasting.

A small pointer used like a pencil for drawing on a video/ computer graphics system.

subcarrier (SC)

In NTSC or PAL video, a continuous sine wave of extremely accurate frequency which constitutes a portion of the video signal. The subcarrier is phase modulated to carry picture hue information and amplitude modulated to carry color saturation information. The NTSC subcarrier frequency is 3.579545 MHz, and the PAL-I frequency is 4.4336187 MHz. A sample of the subcarrier, called color burst, is included in the video signal during horizontal blanking. Color burst serves as a phase reference against which the modulated subcarrier is compared in order to decode the color information.

A small circuit board that mounts on a larger module. Also called a mezzanine.

The physical material upon which an electronic circuit is fabricated.

A functional portion of a larger system.

A luminance level between standard black and sync level. Super black is inserted into the background of a video signal to improve its utility as a source for luminance self keying. It is useful when the foreground of the signal contains some black, which would make a good-quality luminance key difficult to obtain.

A trademarked name for the GVG editor software.

A method of mounting subminiature integrated circuits and other components directly on the surface of a printed circuit board. Permits greater component density on boards, making the electronic equipment smaller.

1. A feature of some GVG switchers which enables the selections made on two mix/effects to be exchanged (selections on M/E 1 transfer to M/E 2 and vice versa). 2. An editor operation that exchanges functions (including machine assignments) of the record device and a source device. Useful in compositing.

Serving wire center.

A generator that produces a periodic deflection of an electron beam on a CRT.

Electronically improving the quality of an audio or video signal, such as by adding sound effects, laugh tracks, and captions.

switcher (production switcher)

Device that allows selection of video sources. Also does transitions between sources and special effects.

switcher channel

Hardware capable of processing one layer of video with all of the switcher channel features (wipes, keys, borderlines, and chroma keys, etc.).

The portion of an encoded video signal that occurs during blanking and is used to synchronize the operation of cameras, monitors, and other equipment. Horizontal sync occurs within the blanking period in each horizontal scanning line, and vertical sync occurs within the vertical blanking period.

A function of a video device that adds sync to the video signal. In component video, sync add is typically used when there is no sync on the green channel of an RGB signal.

Device that generates synchronizing pulses needed by video source equipment to provide proper equipment or studio timing. Pulses typically produced by a sync generator include subcarrier, burst flag, sync, blanking, H & V drives, color frame identification, and color black.

sync processing

See blanking processor.

synchronizing pulse generator (SPG)

See sync generator.

A transmission procedure by which the bit and character stream are slaved to accurately synchronized clocks, both at the receiving and sending end.

Timing pulses added to a video signal to keep the entire video process synchronized in time.

sync timebase error

See timebase error.

The furthest negative excursion level of the sync pulses.

A synchronizing bit pattern, differentiated from the normal data bit patterns, used to identify reference points in the digital television signal; also to facilitate word framing in a serial receiver.

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