#!/usr/bin/env python
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Reassembly of DVB PSI Tables
Components that take a stream of MPEG Transport stream packets containing
Programme Status Information (PSI) tables and reassembles the table sections,
ready for parsing of the data within them.
ReassemblePSITables can do this for a stream of packets containing a single
ReassemblePSITablesService provides a full service capable of reassembling
multiple tables from a multiplexed stream of packets, and distributing them to
Example Usage
A simple pipeline to receive, parse and display the Event Information Table in a
    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( OneShot( msg=["ADD", [0x2000] ] ),    # take all packets of all PIDs
              Tuner(FREQUENCY, feparams),
              DVB_SoftDemuxer( { EIT_PID : ["outbox"] } ),
Set up a dvb tuner and demultiplexer as a service; then set up a PSI tables
service (that subscribes to the demuxer); then finally subscribe to the PSI
tables service to get Event Information Tables and parse and display them::
    RegisterService( Receiver( FREQUENCY, FE_PARAMS, 0 ),
    RegisterService( \
        Graphline( PSI     = ReassemblePSITablesService(),
                   DEMUXER = ToService("DEMUXER"),
                   linkages = {
                       ("PSI", "pid_request") : ("DEMUXER", "inbox"),
                       ("",    "request")     : ("PSI",     "request"),
    Pipeline( Subscribe("PSI", [EIT_PID]),
In the above example, the final pipeline subscribes to the 'PSI' service,
requesting the PSI tables in MPEG Transport Stream packets with packet id 0x12.
The ReassemblePSITablesService service uses a ToService component to send its
own requests to the 'DEMUXER' service to ask for MPEG Transport Stream packets
with the packet ids it needs.
ReassemblePSITables reassembles one PSI table at a time from a stream of
MPEG transport stream packets containing that table.
Send individual MPEG Transport Stream packets to the "inbox" inbox containing
fragments of a particular PSI table.
ReassemblePSITables will reconstruct the table sections. As soon as a section is
complete, it will be sent, as a raw binary string, out of the "outbox" outbox.
The process repeats indefinitely.
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.
ReassemblePSITablesService provides a full service capable of reassembling
multiple tables from a multiplexed stream of packets, and distributing them to
ReassemblePSITablesServices takes individual MPEG Transport Stream packets sent
to its "inbox" inbox and reconstructs table sections, distributing them to
clients/subscribers that have requested them.
To be a client you can wrap ReassemblePSITablesService into a named service
by using a Kamaelia.Experiment.Services.RegisterService component, and then
subscribe to it using a Kamaelia.Experiment.Services.SubscribeTo component.
Alternatively, send a 'ADD' or 'REMOVE' message to its "request" inbox,
requesting to be sent (or no longer be sent) tables from packets of particular
PIDs, and specifying the inbox to which you want the packets to be sent. The
format of these requests is::
    ("ADD",    [pid, pid, ...], (dest_component, dest_inboxname))
    ("REMOVE", [pid, pid, ...], (dest_component, dest_inboxname))
ReassemblePSITablesService will automatically do the wiring or unwiring needed
to ensure the packets you have requested get sent to the inbox you specified.
Send an 'ADD' request, and you will immediately start receiving tables in
those PIDs. Send a 'REMOVE' request and you will shortly no longer receive
tables in the PIDs you specify. Note that you may still receive some tables
after your 'REMOVE' request.
ReassemblePSITablesService will also send its own requests (in the same format)
out of its "pid_request" outbox. You can wire this up to the source of transport
stream packets, so that ReassemblePSITablesService can tell that source what
PIDs it needs. Alternatively, simply ensure that your source is already sending
all the PIDs your ReassemblePSITablesService component will need.
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.
How does it work?
ReassemblePSITablesService creates an outbox for each subscriber destination,
and wires from it to the destination.
For each PID that needs to be processed, a ReassemblePSITables component is
created to handle reconstruction of that particular table.Transport Stream
packets arriving at the "inbox" inbox are sent to the relevant
ReassemblePSITables component for table reconstruction. Reconstructed tables
coming back from each ReassemblePSITables component are forwarded to all
destinations that have subscribed to it.
When ReassemblePSITablesServices starts or stops using packets of a given PID,
an 'add' or 'remove' message is also sent out of the "pid_request" outbox::
    ("ADD",    [pid], (self, "inbox"))
    ("REMOVE", [pid], (self, "inbox"))
This can be wired up to the source of transport stream packets, so that
ReassemblePSITablesService can tell that source what PIDs it needs.
from Axon.Component import component
from Axon.Ipc import shutdownMicroprocess, producerFinished
from Axon.AdaptiveCommsComponent import AdaptiveCommsComponent
# improved PSI packet reconstructor to handle multiple packets
# this one is a service you subscribe to:
# send it a request asking to be sent PSI packets from a given set of PIDs
# and it'll instantiate ReassemblePSITables components as required and
# route the results to the inbox you provided.
class ReassemblePSITables(component):
    Takes DVB Transport stream packets for a given PID and reconstructs the
    PSI packets from within the stream.
    Will only handle stream from a single PID.
    def shutdown(self):
        while self.dataReady("control"):
            msg = self.recv("control")
            if isinstance(msg, (shutdownMicroprocess, producerFinished)):
                return True
        return False
    def main(self):
        buffer = ""
        nextCont = None
        # XXX assuming for the moment that this can only handle one PID at a time
        while not self.shutdown():
            while self.dataReady("inbox"):
                data = self.recv("inbox")
                byte = ord(data[1])
                start_indicator = (byte & 0x40) != 0
                byte = ord(data[3])
                adaption   = (byte & 0x30) >> 4
                contcount  = byte & 0x0f
                # check continuity counter is okay (otherwise ignore packet)
                # or that its the start of a new packet and we've not started receiving yet
                if (nextCont == None and start_indicator) or nextCont == contcount:
                    # determine start of payload offset
                    if adaption == 1:
                        payload_start = 4
                    elif adaption == 3:
                        payload_start = 4+1+ord(data[4])    # skip past adaption data
                    else: # adaption == 0 or adaption == 2
                        # ignore if adaption field==0 or no payload
                    # if start of new payload present, flush previous, now complete, packet
                    if start_indicator:
                        prevstart = payload_start
                        payload_start = prevstart + ord(data[prevstart]) + 1
                        buffer = buffer + data[prevstart+1:payload_start]
                        if len(buffer) and nextCont != None:   # don't flush through dregs if this is the first time
                            self.send( buffer, "outbox" )
                        buffer = ""
                    buffer = buffer + data[payload_start:]
                    # examine PSI section at start of buffer
                    while len(buffer)>=1:
                        if buffer[0] == chr(0xff):
                            # table ID is 'stuffing' id, indicating that everything after
                            # this point is just stuffing, so can be discarded
                            buffer = ""
                        if len(buffer)>=3:
                            # extract the table length field and see if we have a complete table in the buffer
                            tlen = ( (ord(buffer[1]) << 8) + ord(buffer[2]) ) & 0x0fff
                            if len(buffer) >= 3+tlen:
                                self.send( buffer[:3+tlen], "outbox" )
                                buffer = buffer[3+tlen:]
                    nextCont = (contcount + 1) & 0xf
                    # reset for crash relock
                    nextCont = None
                    buffer= ""
            yield 1
class ReassemblePSITablesService(AdaptiveCommsComponent):
    ReassemblePSITablesService() -> new ReassemblePSITablesService component.
    Subscribe to PSI packets by sending ("ADD", (component,inbox), [PIDs] ) to "request"
    Unsubscribe by sending ("REMOVE", (component,inbox), [PIDs] ) to "request"
    Inboxes = { "inbox" : "Incoming DVB TS packets",
                "control" : "Shutdown signalling",
                "request" : "Place for subscribing/unsubscribing from different PSI packet streams",
    Outboxes = { "outbox" : "NOT USED",
                 "signal" : "Shutdown signalling",
                 "pid_request" : "For issuing requests for PIDs",
    def __init__(self):
        # pid handlers: key,value = PID,(outboxname,ctrlboxname,inboxname,PSIcomponent)
        # ( outbox, ctrlbox ----> PSIcomponent ----> inbox )
        self.activePids = {}
        # key,value = PID, [outboxnames]
        self.destinations = {}
        # key,value = (component, inbox),(outboxname, linkage, [PIDs])
        self.subscriptions = {}
    def shutdown(self):
        while self.dataReady("control"):
            msg = self.recv("control")
            if isinstance(msg,(producerFinished,shutdownMicroprocess)):
                return True
        return False
    def handleSubscribeUnsubscribe(self, msg):
        cmd, pids, dest = msg
        if cmd=="ADD":
            # add (or fetch existing) outbox going to this destination
                recipientOutbox, linkage, subscribedToPids = self.subscriptions[dest]
            except KeyError:
                recipientOutbox = self.addOutbox("outbox")
                linkage = self.link( (self, recipientOutbox), dest)
                subscribedToPids = []
                self.subscriptions[dest] = recipientOutbox, linkage, subscribedToPids
            for pid in pids:
                # add (or fetch existing) PSI packet reconstructor for this PID
                    outboxname, ctrlboxname, inboxname, PSIcomponent = self.activePids[pid]
                except KeyError:
                    # set up a new PSI packet reconstructor
                    outboxname = self.addOutbox("_toReassembler_"+str(pid))
                    inboxname  = self.addInbox("_fromReassembler_"+str(pid))
                    ctrlboxname = self.addOutbox("_signalReassembler_"+str(pid))
                    PSIcomponent = ReassemblePSITables().activate()
                    self.activePids[pid] = outboxname, ctrlboxname, inboxname, PSIcomponent
                    # and subscribe to the PID for it
                    self.send( ("ADD",[pid],(self,"inbox")), "pid_request")
                # add (or fetch existing) routing for this PID
                    recipientOutboxes = self.destinations[pid]
                except KeyError:
                    recipientOutboxes = []
                    self.destinations[pid] = recipientOutboxes
                # for this pid, make sure our outbox is one of the recipients
                if recipientOutbox not in recipientOutboxes:
                # for this outbox, add to the list of pids it receives
                if pid not in subscribedToPids:
        elif cmd=="REMOVE":
            # work out which outbox we must be using
                recipientOutbox, linkage, subscribedToPids = self.subscriptions[dest]
            except KeyError:
            for pid in pids:
                if pid in subscribedToPids:
                    # if nobody is subscribed to this pid anymore, clean up the PSI reconstructor component etc
                    if not self.destinations[pid]:
                        del self.destinations[pid]
                        # shutdown the PSI reconstructor, unlink from it, and delete inboxes/outboxes
                        outboxname, ctrlboxname, inboxname, PSIcomponent = self.activePids[pid]
                        self.send(shutdownMicroprocess(self), ctrlboxname)
                        del self.activePids[pid]
                        # and unsubscribe from the PID for it
                        self.send( ("REMOVE",[pid],(self,"inbox")), "pid_request")
            # if no longer subscribed to any PIDs on this destination, then clean it up
            if not subscribedToPids:
                self.unlink(thelinkage = linkage)
                del self.subscriptions[dest]
    def main(self):
        while not self.shutdown():
            while self.dataReady("request"):
            # route incoming transport stream packets according to PID to the
            # appropriate reconstructor
            while self.dataReady("inbox"):
                ts_packet = self.recv("inbox")
                pid = ((ord(ts_packet[1]) << 8) + ord(ts_packet[2])) & 0x01fff
                    toReassemblerBox = self.activePids[pid][0]
                    self.send(ts_packet, toReassemblerBox)
                except KeyError:
                    # not interested in this PID
            # receive any reconstructed PSI packets from the reconstructors and
            # route to the subscribed destinations
            for pid in self.activePids:
                inbox = self.activePids[pid][2]
                while self.dataReady(inbox):
                    psi_packet = self.recv(inbox)
                    for outbox in self.destinations[pid]:
                        self.send(psi_packet, outbox)
            yield 1
__kamaelia_components__ = ( ReassemblePSITables,
                            ReassemblePSITablesService, )
if __name__ == "__main__":
    from Kamaelia.Chassis.Pipeline import Pipeline
    from Kamaelia.Util.Console import ConsoleEchoer
    class ReassemblePSITables(component):
        """Fake packet reconstructor."""
        def main(self):
            print "Reassembler",self.id,"starts"
            while not self.dataReady("control"):
                while self.dataReady("inbox"):
                yield 1
            print "Reassembler",self.id,"terminates"
    import random
    class Producer(component):
        """Fake source of packets"""
        def main(self):
            while 1:
                pid = random.randrange(0,6)
                fakepacket = "X" + chr(pid>>8) + chr(pid & 0xff) + "Y"*185
                yield 1
    class Subscriber(component):
        def __init__(self, spacing, *pids):
            self.notsubscribed = list(pids)
            self.subscribed = []
            self.spacing = " "*spacing
        def takesomefrom(self,source):
            items = []
            if len(source):
                qty = 1+random.randrange(0,len(source))
                for _ in range(0,qty):
                    i = random.randrange(0,len(source))
                    del source[i]
            return items
        def changeSubscription(self):
            if random.randrange(0,2) == 1:
                pids = self.takesomefrom(self.notsubscribed)
                self.send( ("ADD",pids,(self,"inbox")), "outbox")
                pids = self.takesomefrom(self.subscribed)
                self.send( ("REMOVE",pids,(self,"inbox")), "outbox")
            print self.spacing,"Now subscribed to pids:"
            print self.spacing,"  ",self.subscribed
        def main(self):
            nextchangetime = self.scheduler.time + random.randrange(5,10)
            self.notyetreceived = self.subscribed[:]
            while 1:
                while self.dataReady("inbox"):
                    packet = self.recv("inbox")
                    pid = ((ord(packet[1]) << 8) + ord(packet[2])) & 0x1fff
                    if pid not in self.subscribed:
                        print self.spacing,"Shouldn't have received pid:",pid
                        if pid in self.notyetreceived:
                            print self.spacing,"Received 1st of pid:",pid
                if self.scheduler.time >= nextchangetime:
                    nextchangetime = self.scheduler.time + random.randrange(10,20)
                    self.notyetreceived = self.subscribed[:]
                if self.subscribed:
                yield 1
    svc = ReassemblePSITablesService()
    src = Pipeline(Producer(),svc)
    Subscriber(28+0,  1,2,3,4,5).activate()
    Subscriber(28+25, 1,2,3,4,5).activate()
#    from Kamaelia.Util.Introspector import Introspector
#    from Kamaelia.Internet.TCPClient import TCPClient
#    Pipeline(Introspector(),TCPClient("r44116",1500)).activate()
    print "May take several seconds before you see any activity..."
    print "---PSI Reassemblers------|---1st subscriber:------|---2nd subscriber:------"