Quantizing
The process of sampling an analog waveform to provide packets of digital information to represent the original analog signal. See also: Into digits.
QuickTime QuickTime is a multimedia framework developed by Apple Inc. capable of handling various formats of digital video, media clips, sound, text, animation, music, and several types of interactive panoramic images. Running on either OSX or Windows operating systems, QuickTime supports software packages including iTunes, QuickTime Player and Safari.
RAID
A B C D E F G H I J
K L
M N O P Q R S T U V
W X Y Z
Redundant Array of Independent Disks. A grouping of standard disk drives together with a RAID controller to create storage that acts as one disk to provide performance beyond that available from individual drives. Primarily designed for operation with computers, RAIDs can offer very high capacities, fast data transfer rates and much increased reliability of data. The latter is achieved through disk redundancy so that disk errors or failures can be detected and corrected. A series of RAID configurations is defined by levels and, being designed by computer people, they start counting from zero. Different levels are suited to different applications.
RAID levels Level 0
No redundancy – benefits only of speed and capacity – generated by combining a number of disks.
Level 1
Complete mirror system – two sets of disks both reading and writing the same data. This has the benefits of level 0 plus the security of full redundancy – but at twice the cost. Some performance advantage can be gained in read because only one copy need be read, so two reads can be occurring simultaneously.
Level 2 An array of nine disks. Each byte is recorded with one bit on each of eight disks and a parity bit recorded to the ninth. This level is rarely, if ever, used.
Level 3
An array of n+1 disks recording 512 byte sectors on each of the n disks to create n x 512 ‘super sectors’ + 1 x 512 parity sector on the additional disk which is used to check the data. The minimum unit of transfer is a whole superblock. This is most suitable for systems in which large amounts of sequential data are transferred – such as for audio and video. For these it is the most efficient RAID level since it is never necessary to read/ modify/ write the parity block. It is less suitable for database types of access in which small amounts of data need to be transferred at random.
Level 4
As level 3 but individual blocks can be transferred. When data is written it is necessary to read the old data and parity blocks before writing the new data as well as the updated parity block, which reduces performance.
Level 5
As level 4, but the role of the parity disk is rotated for each block. In level 4 the parity disk receives excessive load for writes and no load for reads. In level 5 the load is balanced across the disks.
DRAM Dynamic RAM. DRAM chips provide high density memories which must be powered and clocked to retain data. Synchronous DRAM (SDRAM) is faster, running up to 200 MHz clockrate. DDRSDRAM is Double Data Rate (DDR) SDRAM and is increasing the performance of many of the newer PC and graphics products. Current available capacities are up to 2 Gb per chip. Their fast access rate has allowed DRAM to replace more expensive SRAM in some applications. DDR 2 increases the data rate and DDR 3 reduces the higher power consumption of DDR 2. There are many more variations and versions to suit specific applications. Development continues.
SRAM
Static RAM memory chips in general behave like dynamic RAM (DRAM) except that static RAMs retain data in a six-transistor cell needing only power to operate (DRAMs require clocks as well). Because of this, current available capacity is lower than DRAM – and costs are higher, but speed is also greater. See also: Flash Memory
Raw data (a.k.a. source data)
Data that has not been processed for use. Digital cinematography cameras can generally output raw data of images that includes the full brightness range it can extract from a scene, and a signal that has not been processed for color or to suit any target viewing conditions – such as cinema or gamma corrected for home TV viewing.
Resolution
A measure of the finest detail that can be seen, or resolved, in a reproduced image. Whilst it is influenced by the number of pixels in the display (e.g. high definition 1920 x 1080, broadcast SDTV 720 x 576 or 720 x 487) note that the pixel numbers do not define the resolution but merely the resolution of that part of the equipment chain. The quality of lenses, picture displays, film processes, edit systems and film scanners, etc., in fact any element in the program stream (from scene to screen), must be taken into account in assessing overall system resolution. See also: Concatenation, MTF R
Resolution independent A term used to describe the notion of equipment that can operate at more than one resolution, though not necessarily at the same time. Historically, most dedicated television equipment was designed to operate at a single resolution although some equipment, especially that using the ITU-R BT.601 standard, could switch between the specific formats and aspect ratios of 525/60 and 625/50. More recently, the advent of the multiple formats of HDTV has encouraged new equipment able to operate with many, or all, of the video standards. In today’s converged media world the gamut
Soft RAID
A RAID system implemented by low level software in the host system instead of a dedicated RAID controller. While saving on hardware, operation consumes some of the host’s power.
RAM
Random access memory – cost-effective memory chips (integrated circuits) used extensively in computers to give fast access (compared to disks, tapes etc. – RAM has no moving parts) and very high data rates. RAM is available in several different forms and has been subjected to Moore’s Law for over three decades.
84
GLOSSARY OF TERMS
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99