Kamaelia.Device.DVB.Parse.ParseEventInformationTable

Parsing Event Information Tables in DVB streams

ParseEventInformationTable parses a reconstructed PSI table from a DVB MPEG Transport Stream, and outputs a dictionary containing the data in the table.

The Event Information Table carries data about the programmes being broadcast both now (present-following data) and in the future (schedule data) and is typically used to drive Electronic Progamme Guides, scheduled recording and "now and next" information displays.

The purpose of the EIT 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)

See Kamaelia.Support.DVB.Descriptors for information on how they are parsed.

Example Usage

A simple pipeline to receive, parse and display the "now and next" information for programmes in the current multiplex, from the Event Information 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,
}

EIT_PID = 0x12

Pipeline( DVB_Multiplex(FREQUENCY, [NIT_PID], feparams),
          DVB_Demuxer({ NIT_PID:["outbox"]}),
          ReassemblePSITables(),
          ParseEventInformationTable_Subset(actual_presentFollowing=True),
          PrettifyEventInformationTable(),
          ConsoleEchoer(),
        ).run()

A slight modification to the pipeline, to convert the parsed tables into a stream of inidividual events:

Pipeline( DVB_Multiplex(FREQUENCY, [NIT_PID], feparams),
          DVB_Demuxer({ NIT_PID:["outbox"]}),
          ReassemblePSITables(),
          ParseEventInformationTable_Subset(actual_presentFollowing=True),
          SimplifyEIT(),
          ConsoleEchoer(),
        ).run()

ParseEventInformationTable / ParseEventInformationTable_Subset

Behaviour

At initialisation, specify what sub tables you want ParseEventInformationTable to process (others will be ignored). Event information is grouped into sub tables according to where it is:

• 'Actual' data describes programmes broadcast in the same actual multiplex as this data
• 'Other' data describes programmes being broadcast in other multiplexes

...and what timeframe it relates to:

• 'present following' data describes the now showing (present) and next (following) programme to be shown
• 'schedule' data describes programmes being shown later, typically over the next 7 or 8 days.

Initialise ParseEventInformationTable by providing a dictionary mapping table ids, to be accepted, to (label, is-present-following-flag) pairs. For example, to accept tables of present-following data for this and other multiplexes:

ParseEventInformationTable(acceptTables = { 0x4e : ("ACTUAL", True),
                                            0x4f : ("OTHER", False),
                                          }

However it is much simpler to use the ParseEventInformationTable_Subset helper funciton to create it for you. For example, the same effect as above can be achieved with:

ParseEventInformationTable_Subset( actual_presentFollowing = True,
                                   other_presentFollowing  = True,
                                   actual_schedule         = False,
                                   other_schedule          = False,
                                 )

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

If the table is unchanged since last time it was parsed, then it will not be sent out. Parsed tables are only sent out when they are new or have just changed.

Note that an EIT table is likely to arrive, and be parsed in lots of separate fragments. Because of the way the data format is defined, it is impossible for ParseEventInformationTable to know for certain when it has received everything!

The parsed table is sent out as a dictionary data structure, like this (list of event descriptors abridged for brevity):

{
    'table_id'            : 78,
    'table_type'          : 'EIT',
    'current'             : 1,
    'actual_other'        : 'ACTUAL',
    'is_present_following': True,
    'transport_stream_id' : 4100,
    'original_network_id' : 9018,
    'events': [
        { 'event_id'      : 8735,
          'running_status': 1,
          'free_CA_mode'  : 0,
          'starttime'     : [2006, 12, 22, 11, 0, 0],
          'duration'      : (0, 30, 0),
          'service_id'    : 4164
          'descriptors': [
              (77, {'type': 'short_event', 'name': 'To Buy or Not to Buy', 'text': 'Series that gives buyers the chance to test-drive a property before they buy it. Sarah Walker and Simon Rimmer are in Birmingham, helping a pair of property professionals. [S]', 'language_code': 'eng'}),
              (80, {'type': 'component', 'stream_content': 1, 'component_type': 3, 'text': 'Video 1', 'component_tag': 1, 'content,type': ('video', '16:9 aspect ratio without pan vectors, 25 Hz'), 'language_code': '   '}),
              (80, {'type': 'component', 'stream_content': 2, 'component_type': 3, 'text': 'Audio 2', 'component_tag': 2, 'content,type': ('audio', 'stereo (2 channel)'), 'language_code': 'eng'}),
              (80, {'type': 'component', 'stream_content': 3, 'component_type': 16, 'text': 'Subtitling 5', 'component_tag': 5, 'content,type': ('DVB subtitles (normal)', 'with no monitor aspect ratio criticality'), 'language_code': '   '}),
              (80, {'type': 'component', 'stream_content': 4, 'component_type': 1, 'text': 'Data 6', 'component_tag': 6, 'content,type': (4, 1), 'language_code': '   '}),

              .....

              (84, {'type': 'content', 'contents': '  '})
          ],
        }
    ]
}

The above example is an event for the service BBC ONE, broadcast at 10:06 GMT on 22nd December 2006. It describes a 'present-following' event that doesn't start until 11:00 GMT. It is therefore describing the 'next' programme that will be on the channel/service.

If this data is sent on through a PrettifyEventInformationTable component, then the equivalent output is a string containing this (again, abridged for brevity):

EIT received:
    Table ID                      : 78
    Table is valid for            : CURRENT (valid)
    Actual or Other n/w           : ACTUAL
    Present-Following or Schedule : Present-Following
    Transport stream id           : 4100
    Original network id           : 9018
    Events:
        Service id : 4164
            Running status         : 1 (NOT RUNNING)
            Start datetime (UTC)   : 2006-12-22 11:00:00
            Duration               : 00:30:00 (hh:mm:ss)
            Scrambled?             : NO
            Event descriptors:
                Descriptor 0x4d : short_event
                    language_code : 'eng'
                    name : 'To Buy or Not to Buy'
                    text : 'Series that gives buyers the chance to test-drive a property before they buy it. Sarah Walker and Simon Rimmer are in Birmingham, helping a pair of property professionals. [S]'
                Descriptor 0x50 : component
                    component_tag : 1
                    component_type : 3
                    content,type : ('video', '16:9 aspect ratio without pan vectors, 25 Hz')
                    language_code : '   '
                    stream_content : 1
                    text : 'Video 1'
                Descriptor 0x50 : component
                    component_tag : 2
                    component_type : 3
                    content,type : ('audio', 'stereo (2 channel)')
                    language_code : 'eng'
                    stream_content : 2
                    text : 'Audio 2'
                Descriptor 0x50 : component
                    component_tag : 5
                    component_type : 16
                    content,type : ('DVB subtitles (normal)', 'with no monitor aspect ratio criticality')
                    language_code : '   '
                    stream_content : 3
                    text : 'Subtitling 5'
                Descriptor 0x50 : component
                    component_tag : 6
                    component_type : 1
                    content,type : (4, 1)
                    language_code : '   '
                    stream_content : 4
                    text : 'Data 6'

                .....

                Descriptor 0x54 : content
                    contents : '  '

ParseEventInformationTable can collect the sections of, and then parse the various types of EIT table simultaneously.

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.

SimplifyEIT

Behaviour

Send parsed event information data to the "inbox" inbox, and individual events, in a simplified form, will be sent out the "outbox" outbox one at a time. For example:

{
    'event_id'       : 8735,
    'when'           : 'NEXT',
    'startdate'      : [2006, 12, 22],
    'starttime'      : [11, 0, 0],
    'duration'       : (0, 30, 0),
    'service'        : 4164,
    'transportstream': 4100,
    'language_code'  : 'eng',
    'name'           : 'To Buy or Not to Buy',
    'description'    : 'Series that gives buyers the chance to test-drive a property before they buy it. Sarah Walker and Simon Rimmer are in Birmingham, helping a pair of property professionals. [S]'
}

The possible values of the 'when' field are:

• "NOW" -- describes a programme that is happening NOW
• "NEXT" -- describes a programme that follows the one happening now
• "SCHEDULED" -- part of a schedule describing programmes happening over the next few days

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.

- acceptTables  - dict of (table_id,string_description) mappings for tables to be accepted (default={0x4e:("ACTUAL",True)})

- actual_presentFollowing  -- If True, parse 'present-following' data for this multiplex (default=True)
- other_presentFollowing   -- If True, parse 'present-following' data for other multiplexes (default=False)
- actual_schedule          -- If True, parse 'schedule' data for this multiplex (default=False)
- other_schedule           -- If True, parse 'schedule' data for other multiplexes (default=False)