Kamaelia.Device.DVB.NowNext

• component NowNextProgrammeJunctionDetect
• component NowNextServiceFilter

• Processing Simplified Now & Next Event Information
  • Example Usage
  • NowNextServiceFilter
    • Behaviour
  • NowNextProgrammeJunctionDetect
    • Behaviour
    • How does it work?

Processing Simplified Now & Next Event Information

These components filter or process simplified events, derived from Event Information Table data containing now and next information.

Convert a parsed EIT table to simplified individual events using the Kamaelia.Devices.DVB.Parse.ParseEventInformationTable.SimplifyEIT component.

NowNextServiceFilter selects information relating to only particular services (channels) in the data.

NowNextProgrammeJunctionDetect detects the point at which one programme ends and another begins - known as the "programme junction". It distinguishes between programme junctions and ammendments to a programme's details.

Example Usage

Tuning to a particular broadcast multiplex and detecting when a new programme starts on service 4164, outputting the information about the new programme:

frequency = 505833330.0/1000000.0
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
BBC_ONE = 4164       # the 'service id' on this particular multiplex

Pipeline( DVB_Multiplex(505833330.0/1000000.0, [EIT_PID], feparams),
          DVB_Demuxer({ EIT_PID:["outbox"]}),
          ReassemblePSITables(),
          ParseEventInformationTable_Subset(True,False,False,False), # now and next for this mux only
          SimplifyEIT(),
          NowNextProgrammeJunctionDetect(),
          NowNextServiceFilter(BBC_ONE),
          ConsoleEchoer(),

The above code receives the broadcast multiplex, reconstructs and parses the Event Information Table in it, then simplifies it to a stream of events. These events are then filtered and processed.

NowNextServiceFilter

NowNextServiceFilter selects information relating to only particular services (channels) in the data.

Behaviour

At initialisation, specify the service id's of the services to be detected as arguments.

Send the parsed and simplified events to this component's "inbox" inbox. Those which match the service id's specified at initialisation will immediately be sent on out of the "outbox" outbox. Those which do not match are discarded.

If a shutdownMicroprocess or producerFinished message is sent to this component's "control" inbox, it will immediately be sent on out of the "signal" outbox. The component will then immediately terminate.

NowNextProgrammeJunctionDetect

NowNextProgrammeJunctionDetect detects the point at which one programme ends and another begins - known as the "programme junction". It distinguishes between programme junctions and ammendments to a programme's details.

Behaviour

Send the parsed and simplified events to this component's "inbox" inbox. This component then distinguishes between ammendments to a programme (such as (a change to to how long it is, or its description) and actual programme junctions (the end of one programme and the start of the next).

A single NowNextProgrammeJunctionDetect instance can handle the events for an unlimited number of services concurrently.

When a programme junction is detected, the event describing the programme that has just started is sent out of the "outbox" and "now" outboxes. Any event describing the 'next' programme that will follow it is sent out the "next" outbox.

If the details of a programme have just been ammended (it is not a junction), then the new event information is sent out of the "now_update" outbox if it relates to the current programme on air; or the "next_update" outbox if it relates to the programme that will follow it.

NowNextProgrammeJunctionDetect only handles 'now' and 'next' events. Events for schedule (electronic programme guide) details are ignored.

If a shutdownMicroprocess or producerFinished message is sent to this component's "control" inbox, it will immediately be sent on out of the "signal" outbox. The component will then immediately terminate.

How does it work?

NowNextProgrammeJunction detect keeps a record of the ids of the 'now' and 'next' events each service.

When an event is received, it is looked up in this table. If the event id matches, then it is assumed to be an ammendment of details. If it does not then it is assumed that a programme junction must be taking place.

---

Kamaelia.Device.DVB.NowNext.NowNextProgrammeJunctionDetect

class NowNextProgrammeJunctionDetect(Axon.Component.component)

NowNextProgrammeJunctionDetect() -> new NowNextJunctionDetect component.

Takes simplified events derived from parsed Event Information Table data and sorts them according to whether they simply ammend/correct details or whether they represent the start of a new programme (a junction).

Inboxes

Outboxes

• signal : Shutdown signalling
• next : new NEXT events, at programme junctions only
• now_update : NOW events, when details change, but its still the same programme
• outbox : new NOW events, at programme junctions only
• next_update : NEXT events, when details change, but its still the same programme
• now : same as for 'outbox' outbox

Methods defined here

Warning!

You should be using the inbox/outbox interface, not these methods (except construction). This documentation is designed as a roadmap as to their functionalilty for maintainers and new component developers.

main(self)

Main loop

shutdown(self)

Shutdown handling

Kamaelia.Device.DVB.NowNext.NowNextServiceFilter

class NowNextServiceFilter(Axon.Component.component)

NowNextServiceFilter(*services) -> new NowNextServiceFilter component.

Filters simplified events from Event Information Tables, only letting through those that match the service ids specified.

Argument list is a list of service id's to be let through by the filter.

Inboxes

Outboxes

Methods defined here

Warning!

You should be using the inbox/outbox interface, not these methods (except construction). This documentation is designed as a roadmap as to their functionalilty for maintainers and new component developers.

__init__(self, *services)

x.__init__(...) initializes x; see x.__class__.__doc__ for signature

main(self)

Main loop.

shutdown(self)

Shutdown handling.