April 2024 - This site, and Kamaelia are being updated. There is significant work needed, and PRs are welcome.
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.
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
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.
Got a problem with the documentation? Something unclear that could be
clearer? Want to help improve it? Constructive criticism is very welcome
- especially if you can suggest a better rewording!
