---
title: Glossary
url: https://doc2.pstreamer.tv/en/manual/references/glossary.html
lang: en
product: Perfect Streamer
version: 2.0.2.405
---

# Glossary

Brief definitions of digital broadcasting and network transmission terms that are used in the manual and in the interface without explanation.

## MPEG-TS transport stream

**SPTS**
  Single Program Transport Stream — a transport stream with a single program (one TV channel). The streamer’s basic unit of work ([SPTS streams](../streamer/spts.md#streamer-spts)).
**MPTS**
  Multi Program Transport Stream — a transport stream with several programs, for example a DVB multiplex ([MPTS streams](../streamer/mpts.md#streamer-mpts)).
**PID**
  Packet Identifier — a 13-bit number in the header of every transport stream packet. Packets of one component — video, audio, a service table — carry the same PID. PID 8191 is reserved for null (NULL) packets.
**PAT**
  Program Association Table — the table of the stream’s programs, always on PID 0. For each program it gives the program number and the PID of its PMT table.
**PMT**
  Program Map Table — the table of a program’s composition: the PIDs of video, audio, subtitles and data, as well as the PID on which the PCR stamps are carried.
**NIT**
  Network Information Table — the DVB network table: the network parameters and the composition of its transport streams. Carried on PID 16.
**CC**
  Continuity Counter — a 4-bit continuity counter in the packet header, separate for each PID. A skipped value means packet loss, so CC errors are the first sign of delivery problems ([Analyzer](../streamer/analyzer.md#streamer-analyzer)).
**PCR**
  Program Clock Reference — the program’s reference time stamps at a frequency of 27 MHz. From them the receiver recovers the transmitter’s clock frequency. The analyzer measures PCR interval, drift and accuracy ([Analyzer](../streamer/analyzer.md#streamer-analyzer)).
**PTS**
**DTS**
  Presentation Time Stamp and Decoding Time Stamp — the presentation and decoding time stamps of a frame in the PES header, at a frequency of 90 kHz. DTS differs from PTS only for frames that are decoded earlier than they are presented.

## Network and delivery

**Unicast**
  Delivery of a stream to a single recipient address.
**Multicast**
  Delivery of a stream to a group address (range 224.0.0.0–239.255.255.255): the stream is sent into the network once, and copies are received by everyone who has subscribed to the group. The receiver announces the subscription via the IGMP protocol; switches and routers must support multicast. The source-specific multicast (SSM) variant additionally specifies the source address.
**Listener**
**Caller**
  The two sides of a PS1 and SRT connection. The listener waits for a connection on its own port; the caller connects to a remote address itself. Which side transmits the stream does not depend on this ([SRT](../planning/index.md#planning-srt)).

## License

**HASP id**
  The identifier of the node’s protection key — software or USB. It is shown in the “HASP key” block of the “License” screen ([License](../webui/administration.md#webui-license)). Give it when contacting the supplier about licensing questions.