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P Frames

One of the three types of frames used in the coded MPEG-2 signal. These contain only predictive information (not a whole picture) generated by looking at the difference between the present frame and the previous one. They contain much less data than the I frames and so help towards the low data rates that can be achieved with the MPEG signal. To see the original picture corresponding to a P frame a whole MPEG-2 GOP has to be decoded.
See also: B frames, I frames, MPEG.


A pack consists of a pack header followed by zero or more packets.  It is a layer in the system coding syntax.


A packet consists of a header followed by a number of contiguous bytes from an elementary data stream.  It is a layer in the system coding syntax.

Packet Data

Contiguous bytes of data from an elementary data stream present in the packet.

Packet Identifier  (PID)

A unique integer value used to associate elementary streams of a program in a single or multi-program transport stream.  Every stream (Audio or Video) of an encoder has a Packet Identifier (PID).  These PIDs are either user specified or generated by TCS from the given range.  The scheme followed is site specific.


A method to adjust the average length of an audio frame in time to the duration of the corresponding PCM samples, by continuously adding a slot to the audio frame.

PAL  (Phase Alternating Line)

A single video signal which combines the luminance, chrominance, and synchronization information using the Phase Alternating Line technique.  The television standard used throughout Western Europe, Great Britain, South Africa and Australia.  This technique alternates the phase of the chrominance signal from line to line that makes the signal immune to many typical distortions found in NTSC video.  Each frame of PAL video contains 625 scan lines displayed at 50 fields/25frames per second (625/50 PAL).  PAL-M is a version of the PAL standard used in Brazil, which uses a 525/60 scan.  CCIR Report 624 specifies the international PAL standards.

PAL Composite Video

A single video signal which combines the luminance, chominance and synchronization information using the Phase Alternating Line technique.


A wide screen (16x9) television standard that is broadcast in Europe. It is compatible with existing PAL (4x3) TV sets which show the picture in a letterboxed form. PALplus recordings are in an anamorphic video format.

Pan and Scan

The technique used to crop a widescreen picture to conventional 4:3 television ratio, while panning the original image to follow the on-screen action.

Pan and Scanner

One who pans and scans, typically during a live event originating in a widescreen format (16:9) but simulcast in 4:3.

Pan Pot

Abbreviation for panoramic potentiometer. Allows the placement of sound across individual audio channels. Like a balance control.


A signal path in which the output of one process provides an identical input to several others. 2K Channels are switched between Cascade and Parallel on a scene to scene basis.

Parallel Cable

A multi-conductor cable carrying simultaneous transmission of digital data bits. Analogous to the rows of a marching band passing a review point.

Parallel Communications

Communication lines that carry digital (binary) information between machines using multi-conductor (multi-pin) ribbon cables often with 25 or more conductors. Each conductor carries a single bit-stream of information. Bit-streams of information travel down the cable simultaneously.

Parallel Data

Transmission of data bits in groups along a collection of wires (called a bus). Analogous to the rows of a marching band passing a review point. A typical parallel bus may accommodate transmission of one 8-, 16-, or 32-bit byte at a time.

Parallel Digital

A digital video interface which uses twisted pair wiring and 25-pin D connectors to convey the bits of a digital video signal in parallel. There are various component and composite parallel digital video formats.

Parallel Port   

The input/output port used for simultaneous transmission of data (usually a printer).


A method of verifying the accuracy of transmitted or recorded data. An extra bit appended to an array of data as an accuracy check during transmission. Parity may be even or odd. For odd parity, if the number of 1's in the array is even, a 1 is added in the parity bit to make the total odd. For even parity, if the number of 1's in the array is odd, a 1 is added in the parity bit to make the total even. The receiving computer checks the parity bit and indicates a data error if the number of 1s does not add up to the proper even or odd total.


Playback and Recording System.  Where all the playout resources reside. In addition, where any dubbing and copying will be done.  


The command will insert cut, or copied, material into a specified location.

PAT  (Program Association Table (PID=0))

Patch Bay

A junction panel of connector jacks (patch points) that serve as a convenient location for making all system connections. It consists of two rows of connector jacks which are wired with various signals from the rear of external equipment.

Patch Cords

A short cable, with the appropriate connectors at each end, for use within a patch bay.


The path describes the location of a computer file, from the root (\) or ground level of the DOS operating       system.      For Example: C: WLA YLISTL4PRIL @LIST24.LST is a path that indicates the file LIST24. LST is located in a subdirectory called 4PRIL that is located in the directory PLIYLIST that is stored on drive C: (the hard drive).

Pay-Per-View (PPV)

An audio/video service available by subscribing to single playback.


Payload refers to the bytes that follow the header byte in a packet.  For example, the payload of a transport stream packet includes the PED_packet_header and its PES_packet_data_bytes or pointer_field and PSI sections, or private data.  A PED_packet_payload, however consists only of PED_packet_data_bytes.  The transport stream packet header and adaptation fields are not payload.  


Personal Computer. The automation system runs on computers designed with the IBM (PC) architecture.

PCM (Pulse Code Modulation)

The method used to encode audio in a digital form for CD audio recording, and DAT (Digital Audio Tape). PCM is also used for audio tracks on 8mm and Hi8™ videotape formats.

PCR (Program Clock Reference)

PCS (Playout Control System)

Peak White

A measurement of the maximum light output of a video camera, monitor or video projector without regard to contrast ratio or resolution. Peak White is often used as a specification for video projector light output. The measurement is a brightness reading taken while a small white window is projected on a black background. There is no industry standard for this measurement, and the size of the window varies from manufacturer to manufacturer, making it difficult to compare Peak White readings from one projector to the next.


Photo Electric Cell. The (analog) optical receivers of a flying spot telecine.


See Black.


See pixel.

Pencil Test

                         An animation of simple pencil lines, to test the way elements move and interact.


Precise regularly spaced holes punched throughout the length of a motion picture film to advance and position it in cameras, processing machines, and projectors. Telecines use perfs. to establish frame boundaries.  3 Perf = 3 perfs. per frame :4 Perf = 4 perfs. per frame


A UNIX-based scripting language that is often used on the World Wide Web. When you submit a complex form from your browser window, for example, a Perl script may handle the processing of the information. Perl scripts usually end in the extension .pl.

PES (Packetized Elementary Stream)

Video and audio data packets and ancillary data of undefined length.

PES Packet

The data structure used to carry elementary stream data.  It consists of a packet header followed by PES packet payload.

PES Packet Header:

The leading field in a PES packet up to but not including the PES_packet_data_byte fields where the stream is not a padding stream.  In the case of a padding stream, the PES packet header is defined as the leading fields in a PES packet up to but not including the padding_byte fields.

Phantom Power Supply

A circuit within an audio component designed to provide power to condenser microphones, thus, eliminating the need for batteries.


The timing of an electronic signal. Two signals which occur simultaneously are “in phase;” if they occur at different times, they’re “out of phase.”

Phase Alternating Line (PAL)

The broadcast television standard in Europe as well as other locations, calling for 625 lines per frame transmitted at 25 frames per second. North American standards call for 525 lines per frame transmitted at 30 frames per second.

Phase Locked Loop

A special circuit that is used to accurately generate a range of frequencies. This is an important circuit in frequency agile equipment.


The light emitting surface of a television tube. Several different standards exist for the color emitted by these phosphors.

Pickup Pattern

A microphone’s directional characteristics.


Picture ICONS: On screen visual objects that represent media elements.


A standard format for encoding computer graphics and images (term is an abbreviation of picture).


An update of the PICT adding color support and formatting instructions carried as comments in the image file.


A source image or reconstructed data for a single frame or two interlaced fields. A picture consists of three rectangular matrices of eight-bit numbers representing the luminance and two color difference signals.

PID (Packet Identifier)

Pilot Test

Sometimes referred to as a Beta test, is a trial run of a course or information system with typical targeted audience members used for validation of content, process, delivery, measurements, etc.

Pin Registered

A system for stabilizing film which utilizes precise registration pins which are inserted through the sprocket holes of the film. For perfect registration the film must be pin registered in camera, and then on the telecine. Telecine pin registration is also known as “Steadigating”. The sprocket holes themselves must be manufactured to precise toleration, often called “neg. perfs”.

Pinch Roller

Part of a tape recorder’s transport system. In conjunction with the capstan, pulls the tape through the machine.


The perceived frequency of a sound.  Also the distance from the center of one perforation on a film to the next; or from one thread of a screw to the next; or from one curve of a spiral to the next

Pit Holes

The pits burned into the CD track by the laser when recording. The length, width, and distance between pits determines the information they contain.

Pixel (Picture Element)

1. An acronym for Picture Elements (AKA Pels) and are generally thought of as the smallest complete element of an image. The definition is highly context sensitive. For example, we can speak of pixels in a visible image (e.g. a printed page) or pixels carried by one or more electronic signal(s), or represented by one or more digital value(s), or pixels on a display device. This list is not exhaustive and depending on context there are several synonyms which are accurate in particular contexts, e.g. pel, sample, bytes, bits, dots, spots, superset, triad, stripe set, window, etc. We can also speak of pixels in the abstract, in particular when using pixels as a measure of resolution, e.g. 2400 pixels per inch or 640 pixels per line. Dots is often used to mean pixels, especially by computer sales and marketing people, and gives rise to the abbreviation DPI or dots per inch.
Note that a pixel may be comprised of sub-parts or sub pixels. For example a pixel on a color display may be composed of red, green and blue sub-parts (sub-pixels, sub-pels, etc.) the three of which may be referred to as a triad. A pixel in a video signal may be composed of RGB parts or Y, R-Y, B-Y or Y, I, Q, or Y, C, M or subcarrier modulated Y or composite video or separate signals such as separate ones of the various three sub-pixels above. Many unskilled people, and sometimes skilled people, incorrectly use pixel and image element interchangeably, or use pixel to refer to sub-parts. Unskilled people don't know any better and the skilled people know better but because the meaning is clear from the context do so anyway. Many dictionaries also get it wrong.
Typical pixels we are concerned with in laser printers are those made up of sub-pels in the screening processes, those made up of yellow, cyan and magenta sub-pels in color printing and those which are simply dots of black toner in black and white printers. Typical pixels we are concerned with in television systems are the samples of composite video signals (a single digital value having Y and color subcarrier components) those carried by three electronic signals or three digital values, either Y, R-Y, B-Y or R, G, B depending on where in the TV we are looking and those displayed on the TV screen which are made up of R, G and B color sub-pixels. Note that Y, R-Y and B-Y values are often carried as two electronic signals in television applications, Y in one and time multiplexed R-Y, B-Y in the other.
Image elements is a broader term than pixels and is also highly context sensitive. Image elements includes both complete pixels as well as those various sub-parts of pixels and other elements of images which are not pixel related such as DCT coefficients. For example, it is correct to say that the red part of an RGB pixel is an image element but it is not normally considered correct to refer to the red part as a pixel itself (although persons who are not skilled in the television industry often do).
When someone says a pixel is the smallest part of an image, that statement is incorrect if the image is made up of pixels having sub-parts, but is correct if the pixel is the smallest element (particularly in black and white images or when a single video signal has been sampled). Consequently one can say something like pixels and image elements are essentially the same when talking about technology when the pixel is the smallest part but can disagree that they are the same when talking about technology when the pixel is made up of sub-parts. This tends to confuse the hell out of unskilled people who can't pick up on the intended meaning from the context of the usage.
2. A unit of picture information on imagers, scanners, printers, displays, images, or graphic files. 
3. The basic picture element of a computer screen or graphics sensing array, such as a CCD; the smallest dot a computer can create.  3. The individual “picture elements” on a picture tube or display device.

4. The primary unit of a video image, also known as a "pel".  A pixel is a digital sample of the color intensity values of a picture at a single point.  In a computer display, such as an SVGA, a common number of pixels is 640 horizontally by 480 vertically. The pixel display for one of the 18 video formats in the ATSC standard is 1920 by 1080.  The is 1920 across and 1080 lines.


Pixel Count

Specification of the total number of discrete sensors within a CCD array. This number has a direct bearing on the resolution of the sensing device.

Pixel Depth

Equivalent to bits per pixel. The level of quantizing or potential levels of color or gray scale for each pixel.

Pixel Value

A number or series of numbers that represent the color and luminance of a single pixel. (See Color Value).


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. This effect resembles an image made up of pixels that are too large. Pixelization occurs most frequently in fast moving scenes where a digital compression scheme may get "lost" and momentarily lose picture integrity. These effects can be seen in any digitally encoded video signal such as satellite signals from direct broadcast satellites, DVDs and HDTV. However, the pixelization effect is very rare and always very short-lived (lasting for a mere fraction of a second).

Playback Head

The head that converts the magnetic information on the tape during the playback process.

Play Date      

The date a cassette was last played.


1. The files the On-Air Schedule sends to Automation System. Known as .evf files in the Alamar system, it. tells the Automation System what to play and when.  2. A list of events for transmission. There are separate lists for play events and record events. Each event in the playlist provides instructions to the system for device control during playout of the event. Playlists that originate from a traffic system must be translated by the system before becoming a Louth format playlist. 


The sequential playing of events from a transmission list.

Playout Resource

A tape deck, cart machine, or media pool, controlled by the Automation System and linked to a router.


See Phase Locked Loop above


Picture Line Up Generating Equipment. Now used to mean a specific test pattern used to align the brightness of monitors. The pattern consists of black at -2%, 0% and +2%, and black, mid gray and white patches.

PMT (Program Map Table)


1. A grouping of all commercials and other non-program events. 2. A group of spots that are recorded sequentially during compilation. A pod corresponds to one commercial break between program items.

Point-of-Purchase (POP)

Interactive video units set up in retail areas to demonstrate products, sell goods, advertise services, offer information, etc. to customers.


A conference configuration which allows information to be communicated from one point to many. In some point-to-multipoint videoconferencing systems, the receive sites can transmit back to the point of origination, but not to the other receive sites.


A conference configuration that allows only two sites to communicate with one another. In most cases, both sites can send as well as receive.

Polar Response Diagrams

A graphic representation of a microphone’s pickup pattern.


Post Office Protocol. The protocol used by mail clients to retrieve messages from a mail server.


A place where information goes into or out of a computer.

POS (Point-of-Sale)

A term used when a kiosk or terminal is designated for advertising and promotion of products or services. (See POP).


The amount of time a tape keeps playing after the end of an event.

 Power Tier

An option for the da Vinci 2K that adds 2 extra color channels to the system. One 2K can support up to 4 Power Tiers, providing a total of 9 Power Windows each with its own independent processing.

 Power Window

An option for all digital da Vinci color enhancement systems that generates soft edged areas of an image which can then be color enhanced with independent primary and/or secondary corrections. This allows graduated filter and lighting effects for example.


Point-to-Point Protocol. Communication protocol used over serial lines to support Internet connectivity.

PPR (Program Prep Room)

See QA.

PPV (Pay-Per-View)

An optional service which allows viewers to either call in or select through their IRD (Interactive Receiving Decoder) a program or event being broadcast on a privileged channel.


This is usually expressed as a time constant. Its purpose is to increase the high frequency range. 75 microseconds is the US Standard. It is a type of pre-distortion to compensate for any number of issues such as help the signal to noise in a system. It could also be used to decrease the high frequency range by a given amount, but is not usually used that way.


See: Read before write.


1. Term used to describe the VTR function of cueing to a point on a tape some distance or period of time ahead of the beginning of a recorded material event.  Used to ensure that the VTR is internally synchronized and for synchronizing the beginning of the material event to external events. 2. The amount of time before an event starts when the tape starts rolling. Preroll time is necessary to ensure the tape is up to speed when transmission begins.

Predicted Pictures or P-Pictures or P-Frames

Picture that are coded with respect to the nearest previous I- or P-picture.  This technique is termed forward prediction.  P-pictures provide more compression than I-pictures and serve as a reference for future P-pictures or B-pictures.  P-pictures can propagate coding errors when P-pictures (or B-pictures) are predicted from prior P-pictu5es where the prediction is flawed.

Prediction Profile

Prediction of a picture (P or B) with indication of a motion vector.

Presentation Time Stamp (PTS)

A field that may be present in a PES packet header that indicates the time that a presentation unit is presented in the system target decoder, transmitted every 0.7 sec.

Presentation Unit (PU)

A decided audio access unit or a decoded picture.


(Film) To screen a completed product to a select audience, usually for approval. (Video) To rehearse an edit or change, without recording the result.

 Preview Scene Memory

The Preview Scene Memory preserves automatically the last active panel change not yet stored anywhere else on the system.

Primary Color

In tri-color video or other tri-stimulus color systems, one of the three colors mixed to produce a full-color image. In additive color systems, the primary colors are red, green, and blue. Subtractive color systems use the three color compliments from the additive color system—the subtractive primaries of cyan, magenta, and yellow.

 Primary Correction

In color processing terminology "primary" corrections are those that affect the overall color balance of an image. The da Vinci 888 provides 64 Bit four channel (YRGB) Primary processing


Unwanted transfer of magnetic signal from one layer of a recording tape to the next.

Proc Amp

Short for Processing Amplifier.


The chemical process required to convert the latent image on exposed film stock to its final stable state.

Processing Amplifier

A circuit within the video camera which adjusts the signal levels and characteristics of the video signal output from each of three imagers. Within the camera’s circuitry, the proc amp is located after the imager stage and before matrixing and encoding.


Anything acquired through a contract from a distributor or producer for broadcast or rebroadcast.

Product Manager

The system within TCS that allows you to create, manage, and track all the physical assets (media and material).  The products being managed are the physical media  -- the storage devices -- that contain the material (programs) used for broadcast.  Media include such physical devices as: video tapes or reels, subtitle tapes, audio tapes and video servers (on which programs to be broadcast are stored).

Production Studio

A place where program or other material is produced for future use on air.


A defined subset of the syntax specified in the MPEG-2 video coding specification.

Program Association Table

Indicates the location in TS Multiplex of the corresponding PMT and NIT.

Program Clock Reference (PCR)

A time stamp in the transport stream from which decoder timing is derived, transmitted at least every 0.1 sec.  Reference for the 27-MHz clock regeneration.

Program Element

A generic term for one of the elementary streams or other data streams that may be included in the program.

Program Map Table

Identifies and indicates the locations (with the copyrights) of the streams that make up each service and the location of the Program Clock Reference fields for a service.

Program Specific Information (PSI)

PSI consists of normative data, which is necessary for the demultiplexing of transport streams and the successful regeneration of programs.


Short for progressive scanning. A system of video scanning whereby lines of a picture are transmitted consecutively, such as in the computer world.

Progressive (scan)

Method of scanning lines down a screen where all the lines of a picture are displayed in one vertical scan. There are no fields or
half pictures as with interlace scans. It is commonly used with computer displays and is now starting to be used for some DTV
formats, eg - 1080/24p. The 'p' denotes progressive.

A high picture rate is required to give good movement portrayal, such as for fast action and camera pans, and to avoid a flickery display. For television applications this implies a high bandwidth or data rate and high scanning rates on CRT displays. The vertical definition is equal to around 70% of the number of lines (Kell Factor) and does not show the dither of detail associated with interlaced scans.

                See also:  Interlace, Interlace Factor


A spot, or advertisement; short form material.


Set of syntax rules defining exchange of data including items such as timing, format, sequencing, error checking, etc.

Provider Pricing

Payments to the provider of programming material, such as turnarounds (satellite feeds), spots, PPV, or other.

Proxy Server

A technique used to cache information on a Web server and acts as an intermediary between a Web client and that Web server. This is common for an ISP especially if they have a slow link to the Internet. Proxy servers are also constructs that allow direct Internet access from behind a firewall. They open a socket on the server, and allow communication via that socket to the Internet. For example, if your computer is inside a protected network, and you want to browse the Web using Netscape, you would set up a proxy server on a firewall.

PS  (Program Stream)

Multiplex of several audio and video PES using the same clock.

PSA  (Public Service Announcement)

Pseudo Product

A “product” created by uploading or entering listing service information about a turnaround (satellite) channel. Primarily, its function is to send information to the EPG. It also provides a graphic representation of turnaround (satellite) channel content for the scheduler.

PSI  (Program Specific Information)

PSIP (Program and System Information Protocol) 

ATSC Document A/65 - Revision A and Amendment No. 1 of 31 May 00, speaks to the Program and System Information Protocol for Terrestrial Broadcast and Cable. Click here to go to the ATSC web site. Select the appropriate document listed there for detailed information. http://www.atsc.org/Standards/stan_rps.html  

PTS  (Presentation Time Stamp)

PU  (Presentation Unit)

Pull Down

The telecine transfer relationship of film frames to video fields. Film shot at 24 fps is transferred to 30 fps NTSC video with an alternating two-field/three-field relationship.

Pulse and Bar Pattern

A video test signal that is used in measuring the visual fidelity (K-factor) of a video system.  It consists of a squared sine wave pulse and a white bar of equal amplitude. 

Punctured Convolution Code

Inner coding scheme used in the DVB-S


Puncturing (DVB-S) follows, to reduce the increased data rate after convoluting coding; various registers are not used.  The additional redundancy is used for error control.  The two data streams after puncturing are directly applied as I and Q input signals to the QPSK modulator after filtering to fulfil the first Nyquist criterion.

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