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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

P

Patch Cord.
An audio cable used to connect the output of a device to an amplifier or mixer.
Patch Editor.
A category of MIDI software used to control the sound characteristics of a synthesizer from a computer.
Patches.
Also variously known as programs, timbres, or voices. The name used for the sounds that can be generated by a MIDI device.
PAL (Phase Alternate Line).
The European colour TV broadcasting standard featuring 625 lines per frame and 25 frames per second (incompatible with the U.S. NTSC system).
Palette.
Some graphics adapters can keep track of a limited number of colours, not all that are presented to it. The palette is the small selection of colours that the graphics adapter uses to approximate the original picture.
Pan-and-Scan.
Method of fitting a widescreen aspect ratio movie onto a narrow 4-by-3 aspect ratio video display by the fitting the movie to the height of the video display and cutting off portions of its sides.
Parabolic Microphone.
Attached to a small bowl-shaped reflector, the microphone picks up weak or distant sounds.
Parallax.
How the positions of objects change relative to one another as you move by them. If your camera looks at a subject from one position and you look at the subject from another, the two of you will see slightly different pictures.
Parallel.
A way of sending computer data over several wires at once. Printers usually use multiwire parallel connections with computers.
Parallel Cutting.
Editing raw footage so that similar or parallel actions are seen one after another, making it look like "everybody's doing it".
Parametric Equalizer.
Type of equalizer that allows the user to adjust a signal's frequency response with complete choice over how to break up the signal and adjust it using amplitude, center frequency and bandwidth.
Passband.
Frequencies a crossover lets pass through; those frequencies not cut off by a crossover network.
Passive.
A device that does not use electrical power to operate, and does not add anything to a signal passing through it.
Passive Crossover.
Crossover that does not require electricity and does not use active circuitry to accomplish its task.
Passive Radiator.
Speaker driver that is not powered and is used in conjunction with a woofer generating movement by being vibrated by the back-pressure of the powered woofer.
Passive Matrix.
Inexpensive liquid crystal used in LCD panels that show static pictures and data.
Patch Cable.
Low level cable used to transfer information in an electronic form between components in an audio/video system (see Interconnect).
PCI bus.
Peripheral Component Interchange bus which can pipe data between computer components at 132 MBps.
PCM (Pulse Code Modulation).
Frequently used format for creating digital signals from analog signals and then recreating the analog signals with a digital-to-analog converter.
Peak Output.
Maximum output (sound pressure level) in decibels a speaker can produce without distorting.
Peak Clamping.
Electronically limiting the maximum video signal level to a certain strength, like 100 IRE.
Peak Power.
Amplifier power in watts available for a short time when needed to reproduce loud, sudden sounds (transients).
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 level and all gray levels.
Perceptual Coding.
Method of reducing the amount of data in an audio or video signal by eliminating or reducing the data that human senses cannot perceive or cannot perceive well in a specific circumstance.
Period.
The time required for one cycle in a periodic waveform. Period is the inverse of frequency.
Persistence of Vision.
Aspect of the function of human eyes (specifically the retina) and how the brain holds an image for a small fraction of a second enabling a series of rapidly changing still images to generate the appearance of motion; principle of human sight that makes video and movies possible.
Phase.
  • The timing of when electrical or sound vibrations reach a place, like an input or a microphone. When IN PHASE, the vibrations strengthen each other, making a strong signal. OUT-OF-PHASE signals cancel each other out, weakening the result. Electrical and sound signals need to be kept IN PHASE.
  • The relative position of a wave to some reference point.
    • Phase Adjustment.
    Switch or similar control device that allows a speaker's phase to be shifted or changed in order to generate sound waves that are in-phase with other sound waves.
    Phase Error.
    A change in the colour subcarrier signal which moves its timing out of phase, i.e., it occurs at a different instant from the original signal. Since colour information is encoded in a video signal as a relation between the colour subcarrier and the colour burst phase, a deviation in the colour subcarrier phase results in a change in the image's hue.
    Phase Reversal.
    Undesirable situation where one audio signal has its vibrations going the opposite to another audio signal so that when combined the result is weak and tinny sounding.
    Phono or RCA plug.
    Small connector used to carry audio signals and, in home video equipment, video signals and sometimes RF signals.
    Photoflood.
    Light bulb, available at photo stores, that can screw into normal lamp sockets but gives off proper colour temperature for TV or film work.
    Phonograph.
    Audio component used to play back sound from a record by means of a stylus that tracks the grooves in the record and creates an electrical signal from them as the record spins at a constant speed.
    Phosphor.
    Element that emits light (red, green and blue light as used in video displays) when it is bombarded by or excited by electrons.
    Pit.
    Microscopic depression in the reflective surface of a digital optical storage medium such as a CD, DVD or laserdisc.
    Pitch.
    1). Position of a tone on a scale from high to low; the frequency of vibrations creating a sound wave. The pitch of the note is determined by the frequency of vibrations creating a sound wave.
    2). A continuous frequency over time.
    Pitch Bend.
    A MIDI controller that can vary the pitch of a sound.
    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 recording/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.
    Picture Tube.
    Common video display device that emits an electron beam onto a glass screen coated in phosphors to generate an image.
    Pink Noise.
    Test tone featuring equal amount of energy per octave of bandwidth.
    PIP (Picture-in-Picture).
    Feature found on televisions allowing one program to be viewed on the entire screen while one or more programs play in small windows superimposed over the base program.
    Pixel.
    Picture element; the smallest individual unit or piece of a video display image.
    Pixelization.
    Distortion effect occurring in compressed digital video signals resulting in the image breaking up into large blocks instead of forming a coherent, high-quality image.
    Plasma Television.
    A flat, shallow, light-weight television system that uses gas excited by an electric pulse to give off ultraviolet rays which in turn excite red, green and blue phosphors to generate an image.
    Plug and Play.
    Ability of a card to operate in a computer automatically without you having to throw DIP switches and run setup software to configure the card to work in your system.
    Plug-in.
    A (usually small) piece of software that adds features to a larger piece of softwar. The idea behind plug-in’s is that a small piece of software is loaded into memory by the larger program, adding a new feature and that users need only install the few plug-ins that they need, out of a much larger pool of possibilities.
    PNG
    Portable Network Graphics, is good for combinations of text and graphics within one image. PNG permits truecolor images, variable transparency, platform-independent display, and a fast 2D interlacing scheme. Currently only supported by Internet Explorer.
    Polyphonic.
    Is the ability to play many different notes at once.
    Posterization.
    Special effect in which the picture is reduced to a small number of colours or luminance levels removing any fine gradations of colour and brightness resulting in an oil painting effect. - Reduces unwanted detail.
    Preamplifier.
    Audio component that adjusts the volume of an audio signal and performs switching functions between attached input devices and an amplifier or group of amplifiers.
    Precedence.
    Effect Phenomenon of human hearing where by the ears are able to localize sounds (determine where they came from) by the difference in time from when the sound first enters one ear to when it enters the other ear.
    Pre-enchancement.
    In many situations, video losses can be anticipated, allowing signal pre-compensation in a way that partially corrects for the losses.
    Presets.
    Typically, the sounds permanently stored by the manufacturer in a sound generating device.
    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 Colour.
    One of three colours that can create all other colours through their mixture but that cannot be created by the mixture of any other colours (red/yellow/blue) N.B. The basic colours used in TV and video systems of red, green and blue.
    Primary Key (Database)
    The candidate key that is selected to identify tuples uniquely within the relation.
    Processing Amplifier.
    Electronic device that modifies and stabilizes video signals by separating the video from the sync and regenerating brand new, "clean" sync as well as adjusting video and colour levels.
    Prosody.
    Prosody refers to the stress and melody course of speech. For example, pronunciation of a question differs strongly from a statement.
    Program Change Message
    A two byte MIDI message used to request that a synthesizer change the currently loaded program.
    Programmable.
    Ability to tell a machine to do something on its own. A VCR's programmable timer stores instructions for when to start and stop recording and what channel to record. It may remember several such instructions covering a period of days or even months.
    Progressive Scan.
    Method of displaying video images in which every horizontal line is drawn on screen in a single pass one after the other to create a complete frame or single full-screen video image
    Proportional or Optical spacing.
    Typography where the space between letters depends on the shape and size of the letters.
    Protocol.
    Standard method of communications so that one machine can send/receive data or commands to / from another.
    Proximity Effect.
    Thunderous bass boost heard when people speak or instruments are played too near the face of a directional microphone.
    Pulse Distribution Amplifier (PDA).
    Electronic device that takes one sync signal and makes several from it, each as strong as the original.
    Pulse Code Modulation.
    Common form of transferring analog information into digital signals by representing analog waveforms with a stream of digital bits forming words that relate the amplitude of a signal at a certain point (the sample).
    Punch-in Assemble Edit.
    An assemble edit executed manually, live, while the actors perform.
    Punch In/Out.
    The ability to start and stop a recording at some point other than the beginning.
    Purity.
    An internal colour TV adjustment done to a picture tube to make the screen colours even and uncontaminated by other colours or patches of colours.

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