Service Description Table

Service Description Table (SDT) is a Service Information table made by DVB .^[1] The Service Description table provides metadata about the services (usually TV or radio channels) which form an MPEG transport stream. Unlike analog, where a single service is broadcast on one frequency, a DVB transmission may contain multiple services transmitted within the MPEG transport stream on the single frequency. Multiple frequencies are used to create a collection of MPEG transport streams which form a DVB network. The SDT contains some details about the services that are contained in the data broadcast in a particular network. The SDT is provided in the MPEG transport streams in data packets with a packet ID (PID) of 0x0011. An SDT with table ID 0x42 provides details about services in the current transport stream. An SDT with table ID 0x46 provides information about services within the DVB network that are carried within MPEG transport streams other than the current one. There will only be one SDT for the current MPEG transport stream (table ID 0x42) and multiple SDT for the other transport streams which for part of the DVB network (table ID 0x46) that are transmitted within each transport stream in a network.

The SDT provides the following information about each service:

• the transport stream id.
• the service id.
• whether or not programme schedules are provided in the transport stream.
• whether or not there is information about the current and next programmes.
• the running status of the service (e.g. starting soon, paused, running or off-air).
• whether or not the service is scrambled.

Further optional information may be provided about each service, such as the name of the service, the name of the broadcaster responsible for the service, service availability or service authority url.^[2]

The SDT uses the MPEG reserved PID 0x0011. See ETSI EN 300 468 for technical details.^[1]

References

External links

• http://www.interactivetvweb.org/tutorials/dtv_intro