Background loading Recording material into a system, such as a nonlinear editor, as a background task. Thus the foreground task continues uninterrupted and when one job is completed, the next is already loaded - potentially increasing the throughput of the editing system.
Background task A secondary operation that is completed while the main (foreground) operation continues uninterrupted. This requires an overhead in machines' capabilities beyond that needed for their primary foreground operation. This has particular benefits in pressured situations where time is short, or simply not available for extra operations - such as during edit sessions, live programming and transmission.
Bandwidth The amount of information that can be passed in a given time. In television a large bandwidth is needed to show sharp picture detail in real time, and so is a factor in the quality of recorded and transmitted images. Digital image systems generally require large bandwidths hence the reason why many storage and transmission systems revert to compression techniques to accommodate the signal.
Bayer filter/mask array Color filter A Bayer array is a pattern of red, green and blue non co-sited filters placed onto an imaging chip (CCD, CMOS) so that it can capture the separate red, blue and green primary colors of the image to make up a color digital image. As our eyes have more resolution for green light than red or blue, there are twice as many green cells as there are red and blue. Some redundancy of the green pixels produces an image which is less noisy and has finer detail than would be achieved if there were and equal number of red, green and blue cells. The R, G and B pixels generated by the Bayer filter need to be 'unmasked' using a complex algorithm to produce white. Traditionally professional TV cameras have used three image sensors, one to pick up each primary color. This arrangement demands that the three are finely registered together and involves a considerably more bulky construction and cost than the still digital cameras and consumer camcorders that use a single chip sensor with a Bayer, or other similar filter. However some new high-end professional cameras now have just one sensor, for example the ARRI D20 and Red.
Best light (pass) Shot by shot color correction to produce the best result for each shot.
Betacam An analog component VTR system for PAL and NTSC television introduced in 1982, using a half-inch tape cassette - very similar to the domestic Betamax. This was developed by Sony and was marketed by them and several other manufacturers. Betacam records the Y, R-Y and B-Y component signals onto tape; many machines were operated with coded (PAL or NTSC) video in and out. Initially developed for the industrial and professional markets the system was enhanced to offer models with full luminance bandwidth (Betacam SP 1986), PCM audio and SDI connections with a great appeal to the broadcast market.
Digital Betacam Introduced in 1990 it was a development of the original analog Betacam VTR that records SD component video and audio digitally onto Betacam- style cassettes. It uses mild intra-field compression to reduce the ITU-R BT.601 sampled video data by about 2:1 to provide a good and much cheaper alternative to the uncompressed D1 format. Betacam SX (1996) was a digital tape recording format which uses a constrained version of MPEG-2 compression at the 4:2:2 profile, Main Level (422P@ML). The compression is 10:1 and uses a 2-frame GOP (one I and one B frame), making it more difficult to edit. It uses half-inch tape cassettes. See also: MPEG-2
B-frames See MPEG-2
Binary Mathematical representation of numbers to base 2, i.e. with only two states, 1 and 0; on and off; or high and low. This is the basis of the mathematics used in digital systems and computing. Binary representation requires a greater number of digits than the base 10, or decimal, system most of us commonly use everyday. For example, the base 10 number 254 is 11111110 in binary. There are important characteristics which determine good digital video equipment design. For example, the result of a binary multiplication contains the sum of digits of the original numbers. For example: 10101111 x 11010100 = 1001000011101100 (in decimal 175 x 212 = 37,100) Each digit is known as a bit. This example multiplies two 8-bit numbers and the result is always a 16-bit number. So, for full accuracy, all the resulting bits should be taken into account. Multiplication is a very common process in digital television equipment (e.g. keying, mixes and dissolves). See also: Bit, Byte, Digital mixing, Dynamic Rounding
Bit (b) Binary digIT = bit. One mathematical bit can define two levels or states, on or off, black or white, 0 or 1 etc.; two bits can define four levels, three bits eight, and so on: generally 2n, where n = the number of bits. In image terms 10 bits can be used to define 1024 levels of brightness from black to white (with ITU-R BT.601 and 709, 64 = black and 940 = white). See also: Byte
Bit rate reduction (BRR) See Compression
BITC Burnt-in Timecode. Timecode that is displayed on the video to which it refers. This is often recorded to provide precise frame references for those viewing on equipment not supplied with timecode readers - originally domestic VCRs and these days, QuickTime viewers.
Blocks and Blocking See MPEG-2
Bluetooth Short-range, up to 100m, wireless data connection in a Personal Area Network. Bluetooth is used in products such as phones, printers, modems and headsets and is acceptable where two or more devices are in proximity to each other and not needing high bandwidth (2 Mb/s max.). It is easy to set up without configuration as Bluetooth devices advertise all services they provide making using the service easily accessible, without network addresses, permissions and all the other considerations that go with typical networks. Website: www.bluetooth.com
Blu-ray Disc (BD) This optical disk can hold 25 GB on a single-layer CD-sized (12cm) disk using 405 nanometer blue-violet lasers. Dual layer disks hold up to 50 GB. Players must be able to decode MPEG-2, H.264/AVC (MPEG-4 part 10) and SMPTE VC-1 coded material. MPEG-2 offers backward compatibility for DVDs while the other two more modern codecs are at least 50 percent more efficient, using less disk space or producing higher quality results. Audio codecs supported are Linear PCM, Dolby Digital, Dolby Digital Plus, Dolby TrueHD, DTS Digital Surround, DTS-HD. The baseline data rate is 36 Mb/s - giving over one-and-a-half hours recording of HD material
on a single layer, or about 13 hours of SD. For Blu-ray Disc movies (BD- ROM) the maximum transfer rate is 54 Mb/s for audio and video, with a maximum of 40 Mb/s for video. Random access allows easy video editing and simultaneous record and playback. The first BD disks were contained in a protective plastic caddy to avoid scratch damage. This made them somewhat bulky so now they are coated with a hard top layer to reduce the possibility of scratch damage and there is no caddy. See also: DVD, HD DVD, Optical disks, Professional Disc Website: www.blu-raydisc.com
Breaking the frame (Stereoscopic) Stereo objects in front of the screen plane (negative parallax) are problematic if they intersect the edge of frame, as contradictory depth cues are sent to the viewer. Essentially one cue is saying that the object is in front of the screen and another is saying that the object is behind it. This problem can be reduced in post production by a technique known as a 'floating window'. This involves applying a partially transparent mask, reducing the strength of the cues on whichever side the object is breaking frame (and simultaneously if there are objects breaking frame both left and right). Another kind of issue is caused by objects moving backwards and forwards over the edge of frame. As an object moves off the edge of a screen one stereo camera signal is lost before the other. The result is that the stereo signal temporarily 'switches off'. This can sometimes be solved by sizing up both images in post, causing the object to move off screen altogether.
Broadband General term referring to faster-than-telephone-modem connections, i.e. receiving (download) much faster than 56 kb/s and transmitting (upload) faster than 28 kb/s. Broadband connects subscribers to the internet via DSL or ADSL over the original copper telephone lines. Cable can offer higher data rates. The higher broadband speeds are capable of carrying live digital TV to homes. See also: ADSL
Browse Method used with some stills stores, graphics systems and nonlinear editing systems to display a selection of reduced size or reduced resolution images to aid choice of stored clips or stills. For moving video, a timeline may be available so clips can be shuttled allowing the full sized images to be brought to use pre-cued. Browse/edit facilities are used in newsroom systems to provide video editing for journalists on their desktops. The material is stored on a browse server and distributed over a network to the many users. Details differ between models but some allow frame-accurate shot selections to be made with the resulting 'cuts decision lists' used to conform a broadcast quality version.
BUC A block upconverter (BUC) is used in the transmission (uplink) of satellite signals. It converts a band (or 'block') of frequencies from a lower frequency to a higher frequency. Modern BUCs convert from the L band to Ku band, C band and Ka band. Older BUCs convert from a 70 MHz intermediate frequency (IF) to Ku band or C band. Most BUCs use phase-locked loop local oscillators and require an external 10 MHz frequency reference to maintain the correct transmit frequency. BUCs used in remote locations are often 2 or 4 W in the Ku band and 5 W in the C band. The 10 MHz reference frequency is usually sent on the same feedline as the main carrier. Many smaller BUCs also get their direct current (DC) over the feedline, using an internal DC block. BUCs are generally used in conjunction with low-noise block converters (LNB). The BUC, being an up-converting device, makes up the 'transmit' side of the system, while the LNB is the down-converting device and makes up the 'receive' side. An example of a system utilizing both a BUC and an LNB is a VSAT system, used for bidirectional Internet access via satellite. The block upconverter is assembled with the LNB in association with an OMT, orthogonal mode transducer to the feed-horn that faces the reflector parabolic dish.
Bug An error in a computer program that causes the system to behave erratically, incorrectly or to stop altogether. Term dates from the original computers with tubes and relays, where real live bugs were attracted by the heat and light and used to get between the relay contacts.
Bus An internal pathway for sending digital signals from one part of a system to another.
BWF Broadcast WAV file - an audio file format based on Microsoft's WAV. It can carry PCM or MPEG encoded audio and adds the metadata, such asa description, originator, date and coding history, needed for interchange between broadcasters. See also: WAV Website: http://tech.ebu.ch/publications
B Byte (B), kilobyte (kB), megabyte (MB), gigabyte (GB), terabyte (TB) and petabyte (PB) 1 Byte (B) = 8 bits (b) which can describe 256 discrete values (brightness, color, etc.). Traditionally, just as computer-folk like to start counting from zero, they also ascribe 2 raised to the power 10, 20, 30, etc. (210, 220, 230, etc.) to the values kilo, mega, giga, etc. which become, 1,024, 1,048,576, 1,073,741,824, etc. This can be difficult to handle for those drilled only in base-10 mathematics. Fortunately, disk drive manufacturers, who have to deal in increasingly vast numbers, describe their storage capacity in powers of 10, so a 100 GB drive has 100,000,000,000 bytes capacity. Observation suggests both systems are continuing in use... which could lead to some confusion.
Traditional New Approx duration @601 @709 2k 1080/60i: 1 kB = 210 bytes = 1,024 B 103 B 2/3 line 1/5 line 1/8 line 1 MB = 220 bytes = 1,048,576 B 106 B 1 frame 1/5 frame 130 lines 1 GB = 230 bytes = 1.074 x 109 B 109 B 47 sec 6.4 sec 3.5 sec 1 TB = 240 bytes = 1.099 x 1012 B 1012 B 131/4 hrs 13/4 hrs 58 mins 1 PB = 250 bytes = 1.126 x 1015 B 1015 B 550 days 74 days 40 days <br />
Currently 3.5-inch hard disk drives store from about 70 GB to 1 TB. Solid- state store chips, RAMs, increment fourfold in capacity every generation now offering up to 8Gb chips (i.e. 8 x 230). Flash memory is now used in some camcorders such as Panasonic’s P2 series. A full frame of standard definition digital television, sampled at 10 bits according to ITU-R BT.601, requires around 1 MB of storage (1.037 MB for 576-line, 876 kB for 480-line systems). HDTV frames comprise up to 5 or 6 times more data, and 2K digital film frames sampled in RGB or X´Y´Z´(DCI colorspace) are about 12 MB. See also: DCI, DRAM, Disk drives, Storage