|
--- | --- |
| B |
- B-ROLL
- Stock footage acquired for miscellaneous needs.
- BACK LIGHT
- 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.
- Also a switch on some camcorders used to compensate exposure for situations where the brightest light is coming from behind the subject.
- BALANCED
- A term describing a transmission line or cable consisting of three conductors, two ungrounded signal conductors (pin 2 “hot” & pin 3 “cold”) whose voltages are opposite in polarity but equal in magnitude with respect to ground (pin 1).
Along the length of any cable, noise may be introduced from external sources such as power cables, RF interference, etc. This noise will be identical on both the hot and cold signal conductors. This is known as a common mode signal - a signal which appears equally on both conductors of a two wire line.
So the “hot” and “cold” conductors carry two signals: A desirable audio signal which has an opposite polarity voltage on each line and unwanted noise which is the same polarity on both lines. This is where the trick of balanced audio kicks in. At the input stage when the inverted audio signal is re-inverted to make both desirable audio signals the same, the noise is also inverted (i.e., put out of phase). Viola... the unwanted noise is cancelled out, leaving only the original signal.
- BANDWIDTH
- (See AUDIO BANDWIDTH and VIDEO BANDWIDTH)
- BARCODE
- A unique code for a compact disc. With recordable CDs, this number is often printed in the clear inner ring of the disc. Some CD recorders can also read this information digitally.
- BEL
- A measure of voltage, current, or power gain. One bel is defined as a tenfold increase in power. If an amplifier increases a signal’s power by 10 times, it’s power gain is 1 bel or 10 decibels (10dB). If power is increased by 100 times, the power gain is 2 bels or 20 decibels.
- BETA or BETAMAX
- Consumer videocassette record/playback tape format using half-inch wide magnetic tape. The Beta system was the first consumer videocassette (VCR) format introduced by Sony in the mid 1970s. Although the format produces a higher quality video signal than VHS, marketing blunders by the Japanese electronics giant sealed the fate of the format. Sony continues to manufacture Beta format videocassettes and VCRs as there still is a small established market for them.
- BETACAM
- Portable, professional, high resolution record/playback tape format using the same videocassette shell as the original Betamax. Unlike its predecessor, it records video in component (YUV) format.
- BETACAM SP
- A superior performance version of Betacam. SP uses metal particle tape and a wider bandwidth recording system.
- BIDIRECTIONAL MICROPHONE
- A microphone that picks up sound to it’s front and rear, minimizing pickup at it’s sides.
- BIT DEPTH
- (See WORD LENGTH)
- BIT RATE
- (See WORD LENGTH)
- BITC (Burnt-In Timecode)
- A visual overlay of time code on a video picture.
- BLACK A TAPE
- The process of recording a black burst signal across the entire length of a videotape. Often done before recording edited footage on the tape to give the tape clean, continuous video sync and to insure there is no video already on the tape.
- BLACK BURST
- A composite color video signal comprised of a sync, color burst and black video. It is used to synchronize (genlock) other video sources to the same sync and color information. Black burst generators are used in video studios to "lock" the entire facility to a common signal ("house sync" or "house black").
- BLACK LEVEL
- The voltage in a video signal which corresponds to black.
- BLANKING LEVEL
- Also known as the pedestal, it is the voltage level produced at the end of each horizontal picture line which separates the portion of the video signal containing the picture information from the portion containing the synchronizing information. This voltage makes the electron beam "invisible" as it moves to draw the next visible line.
- BLANKING INTERVAL (Horizontal & Vertical)
- The horizontal blanking interval is the time between the end of one scanning line and the beginning of the next. The vertical blanking interval is the time between the end of one video field and the beginning of the next. Blanking occurs when a monitor’s electron beam is positioned to start a new line or a new field. The blanking interval is used to instantaneously reduce the beam’s amplitude so that the return trace is invisible. (See VERTICAL INTERVAL SWITCHING)
- BLER (Block Error Rate)
- The “raw” digital error rate, usually measured off media before any error correction, which indicates the number of data blocks that have any bad symbols (bytes) at the C1 error-correction stage. The reason that BLER is a good indicator of overall disc quality is that it essentially indicates the number of errors of all types, since errors that are uncorrectable at C1 get passed to C2 for possible interpolation. The Red Book specifies a maximum BLER of 220 per second, averaged over 10 seconds. Top-quality discs used as masters for replication, should have an average BLER of below 10. A peak of 100 bad-data blocks per second is acceptable for CD-ROM, but an average BLER of 50 per second over the entire disc is a good cut-off point to ensure data integrity.
Audio CDs may play with a high BLER, but when such discs are used as masters for replication purposes, these initial media errors are passed on to the final pressed discs, compounding error correction problems, a factor in reproduced sound quality. A high BLER indicates that their longevity may be limited, and that there may be problems in playing reliably on all types of readers. (See CIRC)
- BLOCKING
- The plotting talent, camera, microphone placement and movement in a film or video production.
- BLUE BOOK
- (See CD-EXTRA)
- BNC (Bayonet Neil-Concelman or British Naval Connector)
- A type of connector used on some consumer and most professional VCRs, video and RF equipment providing a secure twist-lock capability. Bayonet denotes the coupling mechanism, while Neill and Concelman were the inventors of the N and C connectors. Thus, the bayonet mechanism is a method by which the N and C connectors come together in the BNC connector.
- BOARD
- Audio mixing console.
- BOUNDARY MICROPHONE
- A microphone whose capsule is mounted flush with or close to, but a precise distance from, a reflective surface so that there is no phase cancellation of reflected sound at audible frequencies. Also known as a PZM (pressure zone microphone.)
- BUFFER
- An amount of memory which temporarily stores data to help compensate for differences in the transfer rate of data from one device to another.
- BUFFER UNDERRUN
- A buffer underrun occurs when the system cannot keep up a steady stream of data as required by CD recording. The CD recorder has a buffer to protect against interruptions and slowdowns, but if the interruption is so long that the recorder’s buffer is completely emptied, a buffer underrun occurs, writing halts, and most often the recordable CD is irretrievably damaged.
- BURN
- To generate a CD-ROM on a specialised CD-R writer drive. The term ‘burn’ comes from the heat generated by the laser needed to make the pits in the disc.
- BWF
- Acronym for Broadcast WAVE File.
 |
We invite the Production Sound and Multimedia communities to link to this web site.
| Copyright ©2008 |