THOMSON Amethyst III, Руководство пользователя, Страница: 299 / 306

Glossary
Amethyst III DTV Smart Switch 299
User Manual
PCR Program Clock Reference.
A time stamp used in digital video compression that indicates the system
time clock’s (STC) value the instant the time stamped packet leaves the
encoder. In the Moving Pictures Experts Group 2 (MPEG-2) system the
digital video source is clocked at 27 Mhz and the decoder must generate
the same 27 MHz clock so that the encoder and decoder clocks are
synchronized. These clocks are called System Time Clocks (STC). To
synchronize the decoder, the encoder sends a PCR to the decoder. The
decoder receives the packet and compares the STC value with it’s own STC
counter value. If the values are the same then no adjustment is needed but
if the two values are different, the decoder must either reset, speed up, or
slow down its STC.
PID Packet Identifier
A unique integer value used to identify the contents of an MPEG-2
Transport Stream packet (Video components PID, Audio component
PID...).
PMT Program Map Table.
A mandatory MPEG-2 PSI table. Each service has a PMT. It lists the service
component parts (elementary streams of video, audio, location of the PCR
fields, etc.).
PSI Program Specific Information.
Normative data that is necessary for the demultiplexing of transport
streams and the regeneration of programs.
PSIP Program and System Information Protocol.
A method of describing Naming and Navigation data for a multi program
transport stream as defined in ATSC A/65A.
PSU Power Supply Unit.
PTS Presentation Time Stamp.
The PTS is a metadata field in an MPEG transport stream that is used to
achieve synchronization of programs' separate elementary streams (for
example Video, Audio, Subtitles) when presented to the viewer. The PTS
is given in units related to a program's overall clock reference, either
Program Clock Reference (PCR) or System Clock Reference (SCR), which is
also transmitted in the transport stream or program stream.
R, G, B Red, Green, Blue.
Resolution Determined by the number of pixels displayed per line or for a given area.
RRT Rating Region Table (ATSC)
RST Running Status Table (DVB)
The RST gives the status of an event (running/not running). The RST
updates this information and allows timely automatic switching to events.
RTP Real Time Transport Protocol.
T
his Protocol defin
es a s
tandardized packet format for delivering audio
and video over IP networks.
RU Rack Unit. It is a unit of measure used to describe the height of equipment
intended for mounting in a 19-inch rack or a 23-inch rack. One rack unit is
1.75 inches (44.45 mm) high.
SD Standard Definition.