a description, originator, date and coding history, needed for interchange between broadcasters. See also: WAV Website: www.ebu.ch/en/ technical/publications/userguides

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

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

C-mode

In videotape editing, operating in C-mode allows the shots on the source footage reels to be copied to the edit tape in the order they are recorded on the source tapes, rather than the order required for the finished program. So all the selected material from a source reel can be copied before loading another source reel – thus saving spooling and reel changing time. This assumes that none of the edits will need to be changed along the way! The term lives on in the disk-based editing world as the editing disk store can randomly access the footage recorded from the source tape. So C-mode editing on disks not only gives the advantages of faster and more convenient transfers but the edits can be more easily altered in a disk store’s random access environment.

Camera negative (film)

Camera negative film is designed to capture as much detail as possible from scenes. This not only refers to its spatial resolution but also its dynamic resolution. Modern camera negative stock has almost 10 stops’ exposure range and so is able to record detail in both the low-lights and the highlights which are well beyond the range that can be shown on the final print film. This provides latitude to compensate for over or under exposure during the shoot or to change the look of a scene. The latitude

Chroma keying

The process of overlaying one video signal over another, the areas of overlay being defined by a specific range of color, or chrominance, on the background signal. For this to work reliably, the chrominance must have sufficient resolution, or bandwidth. PAL or NTSC coding systems restrict chroma bandwidth and so are of very limited use for making a chroma key which, for many years, was restricted to using live, RGB camera feeds. An objective of the ITU-R BT.601 and 709 digital sampling standards was to allow high quality chroma keying in post production. The 4:2:2 sampling system allows far greater bandwidth for chroma than PAL or NTSC and helped chroma keying, and the whole business of layering, to thrive in post production. High signal quality is still important to derive good keys so some high-end operations favor using RGB (4:4:4) for keying – despite the additional storage requirements. Certainly anything but very mild compression tends to result in keying errors appearing – especially at DCT block boundaries. Chroma keying techniques have continued to advance and use many refinements, to the point where totally convincing composites can be easily created. You can no longer see the join and it may no longer be possible to distinguish between what is real and what is keyed. See also: Color space, Digital keying, Photo-real

is engineered into the film stock by giving it a very low gamma of around 0.6. Exposed and developed camera color negative film has an orange tint and is low in contrast – differing greatly from the un-tinted and high contrast print film. As not only the blue, but also the red and green layers of the film are sensitive to blue light, the orange layer is added below the blue layer to stop blue light going further. All types of film stocks use orange dye but for print films it is bleached away during processing. There are numerous stocks available. High speed stocks work well in lower lights but tend to be more grainy. The opposite is true for low speed stocks.

Cardboarding (Stereoscopic)

Lack of true 3D feel to a shot making it look like it is made from cardboard cutouts. This is also referred to as Cutout Planar Effect. Caused by inadequate depth resolution due to an incorrect matching between the focal length of the recording lens (or CGI camera) and the interocular distance between the cameras. See also: Interocular

CCD

Charge Coupled Device (CCD) – either assembled as a linear or two-dimensional array of light sensitive elements. Light is converted to an electrical charge in a linear fashion – proportional to the brightness impinging on each cell. The cells are coupled to a scanning system which, after analog to digital conversion, presents the image as a series of binary digits. Early CCD arrays were unable to work over a wide range of brightness but they now offer low noise, high resolution imaging up to HDTV level and for digital cinematography. See also: CMOS

CDL

See: Color decision list Checksum

A simple check value of a block of data intended to recognize when data bits are wrongly presented. It is calculated by adding all the bytes in a block. It is fairly easily fooled by typical errors in data transmission systems so that, for most applications, a more sophisticated system such as CRC is preferred. See also: CRC

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GLOSSARY OF TERMS