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206-4218
Packet Identiers (PIDs) Overview
Each RF channel has ve or more associated PIDs assigned in a hierarchy (see diagram
below), and the content of each RF channel is carried in a transport stream.
The transport stream is a packet-based protocol, where each packet has a PID that is used to
uniquely identify packets for particular purposes (video, audio, etc.). This allows multiple video
and audio streams to be multiplexed without receiver confusion. For example, if a stream
contains three video programs, each video program has a unique PID. The PAT PID is always
0x0000 and all other PIDs can be in the range 0x0010 to 0x1ffe, inclusive.
The PAT and PMT are tables that indicate which PIDs are used for which purposes. The PAT
contains a list of PMT PIDs. The PMT contains a list of the PIDs of elementary stream data,
such as audio or video, etc. Typical transport streams contain one PID for the PAT, as well as
three or more PIDs for each program (one for PMT, one for video, and one or more for audio).
The PIDs used for each elementary stream must be unique to allow receivers to properly
demultiplex.
Pro:Idiom adds a third PID type to each PMT. The Pro:Idiom message PID may fall anywhere
in the range 0x0010 to 0x1ffe, inclusive and also must be unique. If Pro:Idiom channels are
present in the target system, ensure that Pro:Idiom message PIDs are never used on any
other streams in that system. To facilitate PID allocation, the OAT100R uses a block of 64
contiguous PIDs that can be moved by selecting the start PID.
Refer to ISO/IEC 13818-1:2000, Section 2.4.3, “Specication of the Transport Stream syntax
and semantics,” for further information.
Program 1
PMT
PAT
Video 1
Audio 1B
Audio 1A
Pro:Idiom *
Program 2
PMT
Video 2
Audio 2B
Audio 2A
Pro:Idiom *
Typical PID
Hierarchy
* For channels with Pro:Idiom encrypted content only.
