capacities on 5.25-inch (12 cm) with technologies including CD, DVD, HD DVD, Blu-ray Disc and HVD, offering capacities of 700 MB, 4.7, 15, 25 and 200 GB, with all but CDs offering dual-layer capability or further generations to double the capacity. Single rate data transfer speeds are 1.23, 10, 36/72, 36/72 and 160 Mb/s – even with multiples of speed, data rates are generally still less than for hard drives. They are all available in ROM and read/write forms. Being removable and robust they provide excellent storage for data and digital media. See also: Blu-ray Disc, DVD, HD DVD, HVD, Professional Disc, XDCAM

Original Camera Negative (OCN) This is the exposed and developed negative film from the camera. Initially it is the only visual record of a shoot and so is highly valuable. Before digits got involved with film the OCN had to withstand being cut, edited and copied to a make a few master interpositives. Now it can be run just once through a film scanner and then put on the shelf. This reduces the risk of damage and makes a digital copy, that itself can easily be copied for further security.

Orthostereoscopic (Stereoscopic)

A B C D E F G H I J

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M N O P Q R S T U V

W X Y Z

A one-to-one condition where what is being displayed is the same as the ‘real world’. For example IMAX 3D is often shot with parallel cameras spaced at the average human adult interpupillary distance (approx 63.5 mm) and with wide angle lenses that closely match an audience member’s view of the screen.

Over sampling Sampling information at a higher resolution than is required for the output format. For example, an HD picture can be regarded as an over sampled version of SD. SD pictures created from down res’d HD are generally clearer, cleaner (lower noise) and sharper than those made directly in SD. An increasing amount of SD material is originated this way. Similarly, 35 mm film provides an over sampled source for SD and HD.

P2 Short form for Professional Plug-In, P2 is a professional digital video storage media format introduced by Panasonic in 2004, and especially tailored to ENG applications. It features tapeless (non-linear) recording of DVCPRO, DVCPRO50, DVCPRO-HD, or AVC-Intra streams on a solid state flash memory card. The P2 Card is essentially a RAID of SD memory cards with an LSI controller tightly packaged in a PC card (formerly PCMCIA) enclosure, so data transfer rate increases as memory capacity increases. See DV, ENG

Pack

A set of clips, mattes and settings for DVE, color corrector, keyer, etc., that are used together to make a video layer in a composited picture.

PAL

Phase Alternating Line. The analog color coding system for television widely used in Europe and throughout the world, almost always with the 625 line/50 field system. It was derived from the NTSC system but by reversing the phase of the reference color burst on alternate lines (Phase Alternating Line) is able to correct for hue shifts caused by phase errors in the transmission path. Bandwidth for the PAL-I system is typically 5.5 MHz luminance, and 1.3 MHz for each of the color difference signals, U and V. Note that the PAL term is frequently used to describe any 625/50I analog format – even if it is component, or in the 576/50I digital television system where PAL coding is not used.

PAL-M

A version of the PAL standard, but using a 525 line 60-field structure. Used only in parts of South America (e.g. Brazil).

PAN

Personal area network used for communicating between computer-based devices, such as phones, mobile TVs and PDAs as well as fixed computers – all within a few meters – and through to other networks – such as The Internet. PANs can be wired, via busses such as USB or IEEE 1394, or wireless (WPAN) using technologies such as Bluetooth.

Parallel processing

Using several processors simultaneously with the aim of increasing speed over single processor performance. It often refers to array processor computer hardware that carries out multiple, often identical, mathematical computations at the same time.

Parallax (Stereoscopic)

This refers to the separation of the left and right images on the projection device or display screen. Positive Parallax puts an object behind the screen (on screen objects in the left eye image are to the left of the same objects in the right eye image). Negative parallax puts an object in front of the screen (on screen objects in the left eye image are to the right of the same objects in the right eye image). Zero or neutral parallax puts an object on the screen (on screen objects in the left eye image are overlaid on the same objects in the right eye image). The only difference between stereo cameras should be parallax or angle between the axes of the lenses, as in Camera Convergence – anything else can disturb the stereo viewing experience. This requires close attention, so that the cameras are set-up the same and with the same filters. Color differences, skewing, vertical misalignment, differential weave and hop, lens flares, poor VFX fixes, scratches and dirt can all cause problems. Fast cuts between shots with strong positive and strong negative parallax can be unsettling in some circumstances. This is because the eyes and brain are being asked to jump uncomfortably quickly between positions and then make sense of the result. This can be mitigated by the use of ‘handing off’ – dynamically changing the convergence of an outgoing shot in relation to an incoming shot. Another method of dealing with this is trying wherever possible to cut between shots that are somewhat close in parallax. Vertical parallax is a vertical offset between stereo images and is very uncomfortable to watch – so it is necessary to remove it during post production if there has been camera misalignment during shooting. Note: The term ‘Parallax’ is sometimes used interchangeably with ‘Congruence’ or ‘Disparity’

Perf Short for perforations. It is a way to describe some information about the format of images on 35mm film by how many of the perforations, or sprocket holes, are used per image. For example, Full Frame is 4 perf.

P-frames See MPEG-2

Photo-real Video and film effects that are constructed in such a way that they look totally real and not synthetic are referred to as photo-real effects. This use of effects has increased rapidly and has changed the way many productions are shot and post produced – leading to lower budgets

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GLOSSARY OF TERMS