A calibrated measure of aperture lens opening. F/Stop is a numerical relationship between the diameter of the lens opening and the focal length of the lens. Common f/stops include f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22. The higher the number, the smaller the lens opening and the less light falling on the imager. In low-light situations, a large aperture (e.g. f/1.4) would be needed.
1. The gradual increase or decrease in the
video level of the picture. In other words, the picture emerges from
black, or recedes into black. 2.
A loss of detail in photographic emulsions caused by age and/or poor
Frequently Asked Questions. A list of questions and answers related to a newsgroup, software, Web site, etc.
FEC (Forward Error Correction)
Error control bits added to useful data in the QAM/QPSK modulator.
The noise produced when the amplified sound from a loudspeaker is picked up by the microphone feeding that speaker. Also caused by feeding the output of a source directly back to its input.
An interactive training term—the action of providing information to a user based on their input in order to reinforce concepts or facts that will improve performance or provide self-evaluation.
A group of parallel optical fibers contained within a common jacket. A bundle may contain from just a few to several hundred fibers.
A method of signal transmission sometimes used for CCTV video transmission. Fiber optics transmit light rather than electricity. Signals must be converted from an electronic to an optical signal prior to transmission and reconverted to an electronic signal at the receiving end. Fiber Optic transmission is capable of transmitting a great deal more information at very high resolution than traditional electronic methods without any of the associated problems of electromagnetic interference.
Fibre Channel (also Fiber Channel)
A high speed data link planned to run up to 2 Gbps on a fiber optic cable. A number of manufacturers are developing products to utilize the Fiber Channel-Arbitrated Loop (FC-AL) serial storage interface at 1 Gbps so that storage devices such as hard disks can be connected. Supports signaling rates from 132.8 Mbps to 1,062.5 Mbps, over a mixture of physical media including optical fiber, video coax, miniature coax, and shielded twisted pair wiring. The standard supports data transmission and framing protocols for the most popular channel and network standards including SCSI, HIPPI, Ethernet, Internet Protocol, and ATM.
One vertical scan of the video display. A field represents one half of a complete video frame. Two fields comprise one video frame. Every 1/60th second (1/50th in PAL) a field is scanned and every 1/30th second (1/25th in PAL) a complete video frame is displayed. Adjacent video lines in a video frame belong to alternate video fields.
A video term signifying one half of one television frame. In NTSC television broadcast, each frame (image) is made up of 525 lines. Two 262.5 horizontal line fields equal one frame. Each field represents either the even or the odd lines of a complete frame. A scanning system that uses even/odd field pairs is defined as interlace scanning. A field equals one-half of a complete television scanning cycle (1/60 of a second NTSC; 1/50 of a second PAL/SECAM). When interlaced, two fields combine to make one video frame with a scanning cycle of 1/30 of a second at a scanning rate of 1/30 of a second in NTSC.
Computer term: The basic categories of information stored in the records in a file—for example, a file of bibliographic information might have Author, Title, and Date fields. Field is also used to describe portions of a sector that contain particular information, such as a sync field.
In videodisc mastering, the order of the video fields established on the videotape during edits or transfers. A tape of field-one dominance has a new picture beginning on field one; with field-two dominance, the new picture begins on field two. The field dominance of the master tape determines on which field the videodisc frames will begin.
The number of fields per second. NTSC field frequency is 60 per second; PAL frequency is 50 per second.
The number of fields per second.
A feature of NTSC waveform monitors, which permits selection of either field 1 or field 2 in a video frame for display.
In NTSC coded signals there are 4 distinct color fields identified by the relationship of color subcarrier to horizontal sync. In Pal the sequence is 8. The Field Relationship must be retained for correct editing, making it impossible to define a cut point with better than 2 frames accuracy in NTSC and 4 in PAL. Component formats, such as D1, DCT and Betacam, do not suffer this restriction.
The PC that stores the database files. Other Clients connect to the file server through the network.
A term first used to refer to the process of transferring A/V material into an LMS. In video server systems, this term refers to the process of transferring A/V material into RAIDs or other non-linear devices.
Software that allows you find out more information about an Internet user, such as their real name and if they are logged in at the present moment.
A firewall is a safeguard utilized by many Local Area Networks (LANs) or Wide Area Networks (WANs) to protect the network from unauthorized access from the outside. They are basically gates that verify the users before they leave or enter the network by way of a User ID, Password or IP address.
Software programs contained in Read Only Memory (ROM) in a hardware device, such as computer cards or boards; or cards containing programs.
1. An opaque
board used to mask a light. 2.
A bit in a specifically reserved place in a binary data stream, used
to report status. e.g. color frame flag in time code
A streak of light
across a frame or frames, caused by reflections or stray light in the
optical system of a camera or telecine.
1)Low contrast. Flatness does not necessarily affect the entire density scale to the same degree. Thus, a picture may be "flat' in the highlight areas, or "flat" in the shadow regions, or both. 2)A video transfer is said to be “flat” if it is remains the same as the original and no changes or enhancements are applied.
A Sony developed, multi-cassette video-tape storage and playback system which can be remotely controlled by an 810 protocol.
A visible fluctuation in the brightness of an image, often a problem in CRT displays if the vertical scan rate is lower than about 50 Hz.
In videodisc applications, an undesirable result of freezing on a single frame that has mixed field dominance (see field Dominance). This results in a rapid oscillation between two images.
A feature where a switcher will always select the previous source as the next preview or preset source. The program/background bus “flip flops” with the preset bus. This feature is useful in live production situations to help you get back to the previous source quickly in case you make a mistake.
An external VTR that is not assigned to a list, but can be temporarily assigned to a list by the system (if the VTR contains the tape with the event ID needed by the list). After the event runs, the VTR is unassigned and again becomes a floater.
FM (Frequency Modulation)
A method of modulation in which the frequency of the carrier voltage is varied with the frequency of the modulating voltage: the greater or louder the modulating signal, the greater the change in carrier frequency.
The distance between the optical center of a lens and the image plane (which in the case of a video camera is the CCD target area). The focal length is measured in millimeters (25mm = about 1 inch) and determines both the magnification and the angle of view of a lens. On a variable focal length lens or zoom lens this measure can be adjusted between two preset focal length extremes.
Audio routing option designed to give studio performers the ability to monitor pre-selected sources.
A schedule event whose start time is determined by the end time of the previous event. Referred to as an "Auto Follow Event" in Sony BZC and BZA cart application software.
Subtitles can be displayed using different fonts. Although they must be highly legible, the subtitles should distract as little as possible from the picture. Accustomed subtitle readers will absorb the information in the subtitles subconsciously. They will not normally receive the subtitles as disturbing to the picture. Line 21 and Teletext do normally not allow for custom fonts but have to rely on built-in decoder fonts in the TV.
A measure of light equal to 1 lumen per square foot. One foot-candle = 10.76 lux. The foot-candle is the unit most commonly employed by light meters used in the United States. However, most camera literature specifies the amount of light required for a camera to operate in lux. It is easy to convert camera specifications in lux to the equivalent specification in foot-candles: divide the specified lux by 10 for equivalent foot-candles.
When used in clauses defining the coded bit stream, indicates that the value shall never be used. This is usually to avoid emulation of start codes.
Refers to the video recording format (e.g. 8mm, Hi8, U-Matic, Betacam, Betacam SP, VHS, VHS-C, S-VHS, M-II, D1, D2, etc.). And the size of a motion picture stock. The standard and tape type of a recording. The dimensions of an image.
The process of both encoding/decoding and resampling digital rates to change a digital signal from one format to another.
FPLL (Frequency and Phase Locked Loop)
The scattering of data over a disk caused by successive recording and deletion operations. Generally this will eventually result in slow data recall-a situation that is not acceptable for video recording or replay. The slowing is caused by the increased time needed to randomly access data. With such stores, defragmentation routines arrange the data (by copying from one part of the disk to another) so that it is accessible in the required order for replay. Clearly any change in replay, be it a transmission running order or the revision of an edit, could require further de-fragmentation. True random access disk stores, able to play frames in any order at video rate, never need de-fragmentation.
One complete TV picture consisting of two interlaced scanned fields. There are two video fields per video frame in interlaced video systems. Every 1/30th second (1/25th for PAL), a complete video frame of 525 lines (625 for PAL) is "painted" on the display.
A frame contains lines of spatial information of a video signal. For progressive video, these lines contain samples starting from one time instant and continuing through successive lines to the bottom of the frame. For interlaced video a frame consists of two fields, a top field and a bottom field. One of these fields will commence one field later than the other.
During media playout, when one event can stop and another starts within one frame, usually used in editing. In NTSC color there are approximately 30 frames per second (fps) - (29.95 fps). There are 50 fps in PAL video.
On optical videodiscs, each frame (or complete picture) has an address or frame number. A frame address is put on each disc frame in the form of a frame address code.
Memory used to store a complete frame of video.
Frame Capture Card
Hardware device or circuit card that grabs a frame from an analog video source and digitizes it.
Similar to digitizers, but this term generally refers to those that can capture a frame in 1/30th of a second. A real-time frame grabber can digitize and display full-motion video.
Frame Interline Transfer (FIT) Device
A CCD which employs both vertical registers (found in IT devices) and a separate vertical storage register (as with FT devices) to facilitate charge transfer. While these devices are the most costly to produce, they have advantages over both FT and IT devices including reduced Smear and an electronic shutter. FIT sensors are found on high-quality broadcast cameras. FIT is a combination of IT (Interline Transfer) and FT (Frame Transfer).
The frame rate of a video source is how fast the source repaints the screen with a new frame. The (M) NTSC system screen is repainted about once every 30th of a second for a frame rate of about 30 frames per second. For (B,D,G,H,I) PAL, the frame rate is 25 frames per second. For computer displays, the frame rate is now usually 72- 75 frames per second.
Frame Rate Conversion
Frame rate conversion is the act of converting one frame rate to another. One real example that poses a difficult problem is that the frame rate of (M) NTSC, about 30 frames per second, is different from a typical computer's display, which may be anywhere from 72 to 75 frames per second (or Hz if you prefer). Therefore, some frame-rate conversion process must be performed before (M) NTSC video can be shown correctly on a computer display. Without frame rate conversion, the screen might look as if it "stalls" every now and then. If there is motion within the video, the objects that are moving may appear to be cut in half.
Frames of Black
The number of frames of video tape automatically left black before a spot.
A digital buffer that, by storage, comparison of sync information to a reference, and timed release of video signals, can continuously adjust the signal for any timing errors. It is used to lock video from a free-running source to a facility reference video in order to be mixed, switched, keyed, or processed downstream.
In digital picture manipulators, the ability to stop or hold a frame of video so that the picture is frozen like a snapshot.
The storing of a single frame of video.
The number of cycles a wave completes in a given time interval. In audio, the rate of repetition in cycles per second (hertz) of musical pitch or electrical signals. Low frequencies are bass; high frequencies are treble.
Frequency Modulation (FM)
A common process to vary the frequency of a carrier signal in proportion to a signal of interest. In NTSC, audio information is transmitted using FM.
The range of frequencies from the lowest to the highest that a particular electronic circuit is capable of handling without distortion. Most circuits have limits to the range of frequencies that they can handle. Frequency response is measured in cycles per second or Hz. The human ear has a frequency response of about 20 to 20,0000 Hz because it can hear and distinguish sounds within this range. In audio systems, a frequency response matching this performance of the ear would be considered high-fidelity. For security systems, audio frequency responses of 50 to 12,000 Hz should be considered sufficient. Video monitors should be capable of at least 4 MHz (million Hertz) to retain the performance of cameras and recorders.
The time spent at the blanking level prior to the horizontal sync pulse in a video waveform. It lies between the end of the active video and the leading edge of the horizontal sync.
An image projected on the audience side of a light-reflecting screen.
Transfer Protocol. A standard protocol for transferring files between remote
computer systems. Until recently, it was used almost exclusively on UNIX
workstations and mainframes, but after PC users gained access to the
Internet it became a popular alternative to BBS systems. The biggest limitation
was that FTP-compliant software usually used a command line interface,
which wasn't easy for beginners to work with. As the Internet grew
in popularity, new standards appeared (Gopher, WWW), providing more
user-friendly front-end software. FTP, however, still remains the popular
choice among power users and computer professionals.
Two-way communication as opposed to simplex or half duplex, or one-way communication. In a two-site duplex videoconference, both parties can send and receive video, audio, and data simultaneously.
Video sequences that emulate those normally seen on television because they have enough images (30 frames per second) to impart smooth motion.
Telecine made by
Sony. Introduced 1999. Multi format (16 mm, S16 mm, 35 mm, S 35 mm),
multi standard (601 SDTV, HDTV and data)
field array CCD device with internal primary color correction.