Audio/Video Glossary

P-CHANNEL: One of the CD subcode channels. The P-channel is used to indicate the gaps between tracks on the disc.
P2: Sony’s wired professional edit control protocol. Using an RS-422 serial data path, P2 allows multiple machines to be addressed on the same line and is a defacto standard used on most VTRs in professional use.
PACKET WRITING: Describes a method of adding data incrementally to a disc in small or large quantities called “packets”. It is possible to even record a single file at a time. Unlike previous methods of writing data to CD (disc-at-once and multisession), packet writing does not waste much time or disc space and there is no arbitrary limit to the number of packets that can be written to a CD.
PAL (Phase Alternate Line): Color TV broadcasting standard used mainly in Western Europe, Australia, most of Asia, and parts of South America and Africa, featuring 625 lines per frame and 50 frames per second. (See NTSC and SECAM)
PANASONIC 5-PIN: (See CONTROL-M)
PCM (Pulse Code Modulation): Digital audio recording format used since the late 1970s. PCM simultaneously captures all bits of a given word length (8 to 48-bits) at various standardized sampling frequencies (11kHz to 192kHz). The standard CD, co-developed by Philips and Sony, uses a 16-bit word length and a sampling rate of 44.1kHz).
PEDESTAL: The pedestal is a small DC voltage step within the video signal indicating a picture’s black level and is used as the reference in a standard video signal for white and all gray levels.
PHANTOM POWER: A DC voltage (generally ranging from +11 to +48 volts) that powers a condenser microphone’s electronics while also providing a polarizing voltage for the mic capsule, eliminating the need for batteries.
Phantom power requires a balanced connection between the microphone and power supply. This connection uses a three-conductor cable. The DC voltage is applied equally to pins 2 (signal positive) and 3 (signal negative) relative to pin 1, which is at ground potential. For example, if a recording console supplies +48V of phantom power, pins 2 and 3 each carry +48 VDC relative to pin 1. Of course, the microphone cable transmits the audio signal as well as this voltage, hence the name “phantom” power. Also known as simplex power.
PHASE ERROR: A change in the color subcarrier signal which moves its timing out of phase, i.e., it occurs at a different instant from the original signal. Since color information is encoded in a video signal as a relation between the color subcarrier and the color burst phase, a deviation in the color subcarrier phase results in a change in the image’s hue.
PHOTO CD: A compact disc format developed by Kodak and Philips, based on the CD-I Bridge specification, used to store photographic images on a CD-ROM for display and printing. Up to 100 high resolution images can be stored on a Photo CD.
PHTHALOCYANINE: An organic dye used to form the data layer in some CD-R discs. This photosensitive layer is what gets “burned” when you write to the disc. The accuracy of the stored information is directly affected by how this dye reacts to the laser in your writer. Mitsui Toatsu Corporation holds a patent on this dye claiming that their formulation is more responsive to the laser providing cleaner, better defined pits with a higher reflectivity and the longest lifetime of any photosensitive dye.
PICTURE SHARPNESS: The fine details in a video picture. A picture appears sharp when it contains fine details and has good contrast. Picture sharpness is easily lost during the record/playback process. Advanced video enhancement equipment is used to improve picture sharpness, especially contrast, and can precompensate for potential losses which might alter an image during processing.
PIP (Picture In Picture): Special effect in which one video image is inserted within another allowing several video images to share a single screen.
PIT: An indentation in an optical medium such as a CD or DVD disc. For reading purposes, a directed laser beam is either absorbed in the pits or reflected off non-indented areas called land. Using various algorithms, the reflections are converted into 0 or 1 data bits. (See also LAND)
POST-PRODUCTION: All production work done after the raw video footage and audio elements have been resorded. Editing, titling, special effects insertion, image enhancement, audio mixing and other production work is done during post-production.
POSTERIZATION: Special effect in which the picture is reduced to a small number of chrominance or luminance levels by removing any fine gradations of color and brightness, resulting in an oil painting effect.
PQ SUBCODE: The compact disc format contains a number of subcode areas named with letters from P to W. The key subcode areas are named P & Q and contain data pertaining to every track’s location on the CD, eq emphasis and copy protection. The mastering engineer performs PQ coding just before cutting the CD PreMaster.
PRE-ENHANCEMENT: In many situations, video losses can be anticipated, allowing signal pre-compensation in a way that partially corrects for the losses. (See LINE COMPENSATION)
PRE-MASTERING: The process of formatting data into the exact image that will appear on an audio CD or CD-ROM. This includes dividing the data into sectors and recording those sectors with the appropriate header (address) and error correction information and adhering to the required file structure (i.e., ISO 9660). In the case of recordable CD systems, premastering and mastering are done in one operation, resulting in a ready-to-read compact disc. A premastered image is ready to be mastered and replicated.
PREVIEW BUS: A processor function allowing the operator to select any incoming video source for viewing prior to actual use. Typically, each signal can be previewed on its own monitor. This is an effective method to check work before going "on the air".
PRIMARY COLOR: One of three basic colors used in most TV and video systems. These base colors consist of red, green and blue.
PROGRAM AREA: The largest area on a compact disc containing the audio or CD-ROM information.
PROGRAM BUS: Similar to the preview bus in concept except that the resulting output is the final signal which goes "on the air".
PZM (Pressure Zone Microphone): (See BOUNDARY MICROPHONE)

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