Kamaelia.Device.DVB.Parse.ParseTimeAndDateTable

• component ParseTimeAndDateTable

• Parsing Time And Date Tables in DVB streams
  • Example Usage
  • Behaviour

Parsing Time And Date Tables in DVB streams

ParseTimeAndDateTable parses a reconstructed PSI table from a DVB MPEG Transport Stream, and outputs the current time and date in UTC (GMT).

The purpose of the TDT and details of the fields within in are defined in the DVB SI specification:

• ETSI EN 300 468 "Digital Video Broadcasting (DVB); Specification for Service Information (SI) in DVB systems" ETSI / EBU (DVB group)

The Time Offset Table (TOT) additionally contains information on the current (and next) timezone offset that applies, as well as duplicating the datetime information. See ParseTimeOffsetTable component.

Example Usage

A simple pipeline to receive, parse and display the Time and Date Table:

FREQUENCY = 505.833330
feparams = {
    "inversion" : dvb3.frontend.INVERSION_AUTO,
    "constellation" : dvb3.frontend.QAM_16,
    "code_rate_HP" : dvb3.frontend.FEC_3_4,
    "code_rate_LP" : dvb3.frontend.FEC_3_4,
}

TDT_PID = 0x14

Pipeline( DVB_Multiplex(FREQUENCY, [TDT_PID], feparams),
          DVB_Demuxer({ TDT_PID:["outbox"]}),
          ReassemblePSITables(),
          ParseTimeAndDateTable(),
          PrettifyTimeAndDateTable(),
          ConsoleEchoer(),
        ).run()

The output will look like this:

[2006, 12, 21, 15, 1, 3]
[2006, 12, 21, 15, 1, 4]
[2006, 12, 21, 15, 1, 5]
[2006, 12, 21, 15, 1, 6]

.....

Behaviour

Send reconstructed PSI table 'sections' to the "inbox" inbox. When all sections of the table have arrived, ParseServiceDescriptionTable will parse the table and send it out of its "outbox" outbox.

The table is output every time it is received. In practice a multiplex is likely to transmit about 1 instance of this table per second, giving a reasonably accurate measure of the current time.

The value output is a simple list/tuple describing the current UTC (GMT) date and time, in the form (year,month,day,hour,minute,second).

For example: 21st December 2006 15:01:03 GMT is represented as:

[2006, 12, 21, 15, 1, 3]

If this data is sent on through a PrettifyTimeAndDateTable component, then the equivalent output is a string of the following form:

TDT received:
   UTC Date now (y,m,d) : 2006 12 21
   UTC Time now (h,m,s) : 15:01:03

If a shutdownMicroprocess or producerFinished message is received on the "control" inbox, then it will immediately be sent on out of the "signal" outbox and the component will then immediately terminate.

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Kamaelia.Device.DVB.Parse.ParseTimeAndDateTable.ParseTimeAndDateTable

class ParseTimeAndDateTable(Axon.Component.component)

ParseTimeAndDateTable() -> new ParseTimeAndDateTable component.

Send reconstructed PSI table sections to the "inbox" inbox. When a complete table is assembled and parsed, the result is sent out of the "outbox" outbox in the form [year,month,day,hour,minute,second]. The times are UTC (GMT).

Inboxes

• control : Shutdown signalling
• inbox : DVB PSI Packets from a single PID containing a TDT table

Outboxes

• outbox : Current date and time (UTC)
• signal : Shutdown signalling

Methods defined here

__init__(self)

main(self)

shutdown(self)