SimpleDVB-T (Digital
Terrestrial TV) Tuner
DVB_Multiplex tunes to the specified DVB-T multiplex and outputs
received MPEG Transport Stream packets that have a PID in the list of
PIDs specified.
If you need to change which PIDs you receive at runtime, consider
using Kamaelia.Device.DVB.Tuner
Example Usage
Receiving PIDs 600 and 601 from MUX 1 broadcast from Crystal Palace
in the UK (this should, effectively, receive the video and audio for the
channel 'BBC ONE'):
from Kamaelia.Chassis.Pipeline import Pipeline
from Kamaelia.Device.DVB.Core import DVB_Multiplex
from Kamaelia.File.Writing import SimpleFileWriter
import dvb3.frontend
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,
}
Pipeline( DVB_Multiplex(505.833330, [600,601], feparams),
SimpleFileWriter("BBC ONE.ts"),
).run()
Receive and record the whole multiplex (all pids):
from Kamaelia.Chassis.Pipeline import Pipeline
from Kamaelia.Device.DVB.Core import DVB_Multiplex
from Kamaelia.File.Writing import SimpleFileWriter
import dvb3.frontend
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,
}
Pipeline( DVB_Multiplex(505.833330, [0x2000], feparams),
SimpleFileWriter("BBC ONE.ts"),
).run()
How does it work?
DVB_Multiplex tunes, using the specified tuning parameters to a DVB-T
transmitted multiplex.
It will output received transport stream packets out of its "outbox"
outbox for those packets with a PID in the list of PIDs specified at
initialization.
Most DVB tuner devices understand a special packet ID of 0x2000 to
request the entire transport stream of all packets with all IDs. Specify
a list containing only this PID to receive the whole transport
stream.
This component will terminate if a shutdownMicroprocess or
producerFinished message is sent to the "control" inbox. The message
will be forwarded on out of the "signal" outbox just before
termination.
SimpleDVB-T (Digital
Terrestrial TV) Demuxer
DVB_Demuxer take in MPEG transport stream packets and routes them to
different outboxes, as specified in a mapping table.
If you need to change which PIDs you receive at runtime, consider
using Kamaelia.Device.DVB.DemuxerService.
Example Usage
Receiving PIDs 600 and 601 from MUX 1 broadcast from Crystal Palace
in the UK (this should, effectively, receive the video and audio for the
channel 'BBC ONE') and write them to separate files, plus also to a
combined file. Plus also record PIDS 610 and 611 (audio and video for
'BBC TWO') to a fourth file:
from Kamaelia.Chassis.Graphline import Graphline
from Kamaelia.Device.DVB.Core import DVB_Multiplex
from Kamaelia.Device.DVB.Core import DVB_Demuxer
from Kamaelia.File.Writing import SimpleFileWriter
import dvb3.frontend
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,
}
Graphline(
RECV = DVB_Multiplex(505.833330, [600,601, 610,611], feparams),
DEMUX = DVB_Demuxer( { 600 : ["outbox","video"],
601 : ["outbox","audio"],
610 : ["two"],
611 : ["two"] } ),
REC_A = SimpleFileWriter("audio.ts"),
REC_V = SimpleFileWriter("video.ts"),
REC_AV = SimpleFileWriter("audio_and_video.ts"),
REC_2 = SimpleFileWriter("audio_and_video2.ts"),
linkages = { ("RECV", "outbox") : ("DEMUX", "inbox"),
("DEMUX", "outbox") : ("REC_AV", "inbox"),
("DEMUX", "audio") : ("REC_A", "inbox"),
("DEMUX", "video") : ("REC_V", "inbox"),
("DEMUX", "two") : ("REC_2", "inbox"),
}
).run()
How does it work?
DVB_Demuxer takes MPEG transport stream packets, sent to its "inbox"
inbox and determines the packet ID (PID) of each, then distributes them
to different outboxes according to a mapping dictionary specified at
intialization.
The dictionary maps individual PIDs to lists of outbox names (the
outboxes to which packets with that given PID should be sent), for
example:
{
600 : ["outbox","video"],
601 : ["outbox","audio"],
610 : ["two"],
611 : ["two"]
}
This example mapping specified that packets with 600 and 601 should
be sent to the "outbox" outbox. Packets with PID 600 should also be sent
to the "video" outbox and packets with PID 601 should also be sent to
the "audio" outbox. Finally, packets with PIDs 610 and 611 should b sent
to the "two" outbox.
The relevant outboxes are automatically created.
If a packet arrives with a PID not featured in the mapping table,
that packet will be discarded.
As in the above example, a packet with a given PID can be mapped to
more than one destination outbox. It will be sent to all outboxes to
which it is mapped.
Packets which have their 'error' or 'scrambled' flag bits set will be
discarded.
This component will terminate if a shutdownMicroprocess or
producerFinished message is sent to the "control" inbox. The message
will be forwarded on out of the "signal" outbox just before
termination.
