User guide

Glossary
PES Packetised Elementary Stream: A sequential stream of data bytes
that has been converted from original elementary streams of audio
and video access units and transported as packets. Each PES
packet consists of a header and a payload of variable length and
subject to a maximum of 64 kbytes. A time stamp is provided by the
MPEG-2 systems layer to ensure correct synchronization between
related elementary streams at the Decoder.
PID Packet Identifier: the header on a packet in an elementary data
stream, which identifies that data stream. An MPEG-2 / DVB
standard.
PIN Personal Identification Number: A password used to control access
to programming and to set purchase limits. Each subscriber
household can activate several PINs and may use them to set
individual parental rating or spending limits for each family member.
Pixel PIX (picture) Element: The digital representation of the smallest
area of a television picture capable of being delineated by the
bit-stream. See Pel for more information.
pk-pk peak to peak: Measurement of a signal or waveform from its most
negative point to its most positive point.
PLL Phase-Locked Loop. A phase-locked loop is a control system which
controls the rotation of an object by comparing its rotational position
(phase) with another rotating object as in the case of a sine wave or
other repeating signal. This type of control system can synchronize
not only the speed, but also the angular position of two waveforms
that are not derived from the same source.
PMT Program Map Table: Part of the MPEG-2 Program Specific
Information (PSI) data and is mandatory for MPEG-2 compliance.
Each service has a PMT, which lists the component parts
(elementary streams of video, audio, etc.) for the various services
being transmitted.
P-picture/P-frame A picture / frame produced using forward prediction. It contains
predictions from either previous I frames or previous P frames. The
P frame is used as a reference for future P or B frames.
ppm
Parts per million.
PPV Pay Per View: A system of payment for viewing services based on a
usage / event basis rather than on on-going subscription.
Subscribers must purchase viewing rights for each PPV event that
they wish to view. PPV events may be purchased as IPPV or OPPV.
Program PC - A sequence of instructions for a computer.
TV - A concept having a precise definition within ISO 13818-1
(MPEG-2). For a transport stream, the timebase is defined by the
PCR. The use of the PCR for timing information creates a virtual
channel within the stream.
Programme A linking of one or more events under the control of a broadcaster.
For example, football match, news, film show. In the MPEG-2
concept, the collection of elementary streams comprising the
programme, have a common start and end time. A series of
programmes are referred to as events.
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