Service Description Table

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The Service Description Table ( SDT ; German program description table ) is a table which contains information about the broadcast programs ( services ) in digital television ( DVB ). Data from the SDT are used to display the program name. It is part of DVB-SI and specified in accordance with ETSI EN 300 468.

The SDT contains information about programs ( services ) in the received and possibly also in other transport streams . It is sent out in packets with the PID 17.

construction

The SDT also contains information in readable form, in particular the transmitted program names (e.g. "ZDF"). In contrast to most of the other service information tables , the information is divided into two sub-tables, each with its own table identification (Table_ID).

These are

  1. Table with table_id 0x42 contains information about programs in the received transport stream
  2. Table with table_id 0x46 contains information about programs from other transport streams

Each section (which contains a maximum of 1 kilobyte of binary data) contains the following information:

  • Table identification (table_id).
  • Transport stream identification (transport_stream_id).
  • Number of the section (section_number) and specification of the last section (last_section_number), whereby the first section always has the number 0 and the numbering must be in ascending order.
  • Information about one or more programs with the following detailed data:
    • Program identification (Service_id).
    • Indication of whether there are entries in the Event Information Table for this program (EIT_schedule_flag)
    • Status of the transmission (running_status), u. a. "Does not work", "starts in a few seconds" "runs". This information can be used for automatic recording control.
    • Transmission is free to receive (i.e. not encrypted) (free_CA_mode).
    • Other broadcast-dependent information that is held in descriptors . Often this is just that
      • Name of the provider and the program (service_descriptor).

The total possible scope of the SDT results from the combination of the two table identifications (table_id), the transport stream identification (transport_stream_id) and the number of the respective section (section_number).

For a typical transport stream in Germany, as it is broadcast in DVB-T , with four programs ( services ), in which only programs of the received transport stream are regularly displayed, the table contains only one section.

Individual evidence

  1. ↑ ETSI: Digital Video Broadcasting (DVB); Specification for Service Information (SI) in DVB systems , chapter 5.2.3 Service Description Table (SDT) . Retrieved April 16, 2015

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