Recording material into a system, such as a nonlinear editor, as a background task. Thus the foreground task may continue uninterrupted and when one job is completed, the next is already loaded, potentially increasing the throughput of the editing system.
The amount of information (data) that can be passed in a given time. In television a large bandwidth is needed to show sharp picture detail in realtime, and so is a factor in the quality of recorded and transmitted images. For example, ITU-R BT.601 and SMPTE RP 125 allow analog luminance bandwidth of 5.5 MHz and chrominance bandwidth of 2.75 MHz for standard definition video. 1080-line HD has a luminance bandwidth of 30 MHz (ITU-R BT.709).
Digital image systems generally require large bandwidths hence the reason why many storage and transmission systems resort to compression techniques to accommodate the signal.
A Bayer filter is a matrix 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 record a color digital image. This greatly simplified the construction of color cameras, and somewhat mimics how our (single-retina) eyes see color. As our eyes have more resolution for green light than red or blue, the Bayer filter on the imaging chip has twice as many green cells as 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 an equal number of red, green and blue cells.
For further use, the R, G and B pixels generated by the Bayer-filter-and-imaging-chip combination need to be ‘unmasked’ using a complex algorithm. This process, sometimes called Debayering, produces the separate red, green and blue images that together make up the color image.
Traditionally professional TV cameras have used three image sensors, one to pick up each primary color. This arrangement requires that behind the lens there is a three-way light-splitting glass block delivering the separate R, G and B images to three light sensors that must be accurately registered together. This has involved a considerably more bulky construction and greater cost than is needed by those based on a single image-sensor chip complete with a Bayer filter.
The Bayer filter was patented in 1976 and early use was with consumer stills and video cameras. A number of other variants of RGB filter array are now in use. It was 30 years later that single-chip cameras started to be accepted for the professional video and movie markets, some years after they had been widely used in high-end stills cameras, for example. ARRI Alexa, Canon, Sony F65/55 and RED.
Shot-by-shot color correction to produce the best result for each shot.
An analog component-video 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.
A digital tape recording format that 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 slightly more difficult to edit. It uses half-inch tape cassettes.
See also: MPEG-2
Broadband Global Area Network comprises three Inmarsat satellites. The service they provide is free of terrestrial troubles such as cellular dead-zones, or disaster service outages, and is available around the world – even on oceans and in deserts. Just make sure there are no obstacles between you and the satellite. Using a small, easy-to-set-up dish, it can offer phone, fax, ISDN, SMS text, and high-speed internet services.
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 the number of digits of the original numbers.
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 so the result is 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) so exactly how such a result is treated to connect with downstream digital products with 8, 10 or 12-bit digital inputs, raises some interesting questions!
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).
Note that in both decimal and binary numbers the first digit describes the largest part of the number’s value. For example, the base-10 number 254 is 11111110 in binary. In binary the first digit of the number is called the most significant bit (MSB). Likewise the last digit is the least significant bit (LSB).
See also: Byte
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 platforms not supplied with timecode readers.
A PAL or NTSC video signal with no picture (black). The signal comprises line and field sync pulses as well as the color ‘burst’ before the start of each active TV line. It was widely used as an accurate timing reference for analog 626 and 525-line color equipment. You might have thought it has passed into history, but you would be wrong. Black and burst is still widely used as a sync reference timing signal for digital formats including SD, HD and UHD.
Founded in 2005, three years after the introduction of the Blu-ray Disc system, the BDA is a voluntary membership group for those interested in creating, manufacturing, or promoting the BD formats and products, as well as those seeking more information about the format as it evolves.
The BDA aims to develop BD specifications, ensure products are correctly implemented, promote wide adoption of the formats and provide useful information to those interested in supporting those formats.
See also: Blu-ray Disc
This optical disk, designed for HD, 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. Also available are triple layer (100 GB) and quadruple layer (128 GB) disks, which may accommodate 4K UHD video. The companies that established the basic specifications were: Hitachi Ltd., LG Electronics Inc., Matsushita Electric Industrial Co. Ltd., Pioneer Corporation, Royal Philips Electronics, Samsung Electronics Co. Ltd., Sharp Corporation, Sony Corporation, and Thomson Multimedia.
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.
Ultra HD Blu-ray is the 4K Blu-ray format, expected for delivery Christmas 2015. Handling 4K UHD video at up to 60 f/s, the specification includes HEVC (H.265) video compression, a wider color gamut (than HD) as well as High Dynamic Range (HDR) and 10-bit video sampling. Disc capacities are set at 66 GB (dual layer) and 100 GB (triple layer). The system will also be able to play legacy standards including Blu-ray, DVD and CD. The final specification is expected in mid-2015.
Short-range, up to 100m, wireless data connection in a Personal Area Network (PAN). 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 (3 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.
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.
General term referring to internet connections that are faster than those using a dial-up telephone modem. 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 services can offer higher data rates, especially those using fiber-optic cable to the home (FTTH). Generally broadband speeds are capable of carrying real-time video to homes, except in the evenings, when everyone else is trying to do the same!
See also: ADSL
A method to help find required image-based material such as stills, graphics and video clips by showing many reduced size images together on a screen so enabling a quick selection of required material. For moving video, a timeline may be also be available so clips can be shuttled, so 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.
Informal word used to describe when streaming media suddenly ‘hits the buffers’ – stops. This is usually due to a lack of bandwidth when viewing video over the internet. In recent years the implementation of adaptive streaming schemes, as well as faster internet, have together greatly reduced the occurrence of buffering, making the viewing of video delivered via the internet a non-buffered experience.
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.
An internal pathway (or connection) for sending digital signals from one part of a system to another.
Broadcast WAV File, a widely used audio file format based on Microsoft’s WAV. It can carry PCM or MPEG encoded audio and adds the metadata, such as a description, originator, date and coding history, needed for interchange between broadcasters.
See also: WAV
Broadcast eXchange Format standardizes interfaces among systems that deal with content metadata, content movement, schedules and as-run information. This is standardized in SMPTE RP 2021 and simplifies interoperability between applications. BXF provides a standard where there were a large number of diverse ‘pet’ or old file and data formats used in areas including schedules, playlists, record lists, as-run lists, content metadata, content movement instructions.
BXF makes it possible for all its users to have a common standard for the efficient exchange of data between all components of broadcast automation and business systems.
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. To be factually correct, these powers of 2 should actually be called kibibyte (KiB), mebibyte (MiB), gibibyte (Gib), tebibyte (TiB) etc., though this is not very commonly seen in practice.
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.
|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||13¼ hrs||1¾ hrs||58 mins|
|1 PB = 250 bytes = 1.126 x 1015 B||1015 B||550 days||74 days||40 days|
Currently 3.5-inch hard disk drives store from about 100 GB to 6 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 widely used in many professional and consumer video cameras.
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. 4K quadruples that to 48 MB. Storing the larger formats as uncompressed or applying ‘lossless’ compression makes huge demands on resources.