DVB Service Information (SI) is an enhancement of MPEG Program Specific Information (PSI). SI is required for automatic tunning of STB upon selection, progamme location, EPG, API and CA. A programme in MPEG is a collection of elements with a common time base only.
The PSI data is structured as four types of table.
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Tuner to Demod - IF signal
Demod to Main IC - ts packet |
1) Program Association Table (PAT)
For each service in the multiplex, the PAT indicates the location (the Packet Identifier (PID) values of the Transport Stream (TS) packets) of the corresponding Program Map Table (PMT). It also gives the location of the Network Information Table (NIT).
2) Conditional Access Table (CAT)
The CAT provides information on the CA systems used in the multiplex; the information is private and dependent on the CA system.
3) Program Map Table (PMT)
The PMT identifies and indicates the locations of the streams that make up each service and the location of the Program Clock Reference fields for a service.
4) Network Information Table (NIT)
It is intended to provide information about the physical network.
In addition to the PSI, data is needed to provide identification of services and events for the user. In contrast with the PAT, CAT, and PMT of the PSI, which give information only for the multiplex in which they are contained (the actual multiplex), the additional information below can also provide information on services and events carried by different multiplexes, and even on other networks. This data is structured as nine tables:
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| Service Delivery Model |
1) Bouquet Association Table (BAT)
The BAT provides information regarding bouquets. As well as giving the name of the bouquet, it provides a list of services for each bouquet.
2) Service Description Table (SDT)
The SDT contains data describing the services in the system e.g. names of services, the service provider, etc.
3) Event Information Table (EIT)
The EIT contains data concerning events or programmes such as event name, start time, duration, etc.; the use of different descriptors allows the transmission of different kinds of event information e.g. for different service types.
4) Running Status Table (RST)
The RST gives the status of an event (running/not running). The RST updates this information and allows timely automatic switching to events.
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| Service Information |
5) Time and Date Table (TDT)
The TDT gives information relating to the present time and date. This information is given in a separate table due to the frequent updating of this information.
6) Time Offset Table (TOT)
The TOT gives information relating to the present time and date and local time offset. This information is given in a separate table due to the frequent updating of the time information.
7) Stuffing Table (ST)
The ST is used to invalidate existing sections, for example at delivery system boundaries.
8) Selection Information Table (SIT)
The SIT is used only in "partial" (i.e. recorded) bitstreams. It carries a summary of the SI information required to describe the streams in the partial bitstream.
9) Discontinuity Information Table (DIT)
The DIT is used only in "partial" (i.e. recorded) bitstreams. It is inserted where the SI information in the partial bitstream may be discontinuous. Where applicable the use of descriptors allows a flexible approach to the organization of the tables and allows for future compatible extensions.
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Demultiplexing/Descrambling, AV Decoder @ Main IC
Tuner + Demod @ Tuner |
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