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administrative uses. It is recommended to use UDP ports 1024 and higher. The BBG-
1090-TRX-MPEG, however, will accept any legal value.
•
Destination Address: selects the IP address to transmit to. Any unicast or multicast
address can be entered here, with the exception of the loopback range (127.0.0.0 to
127.255.255.255). The BBG-1090-TRX-MPEG will also accept the broadcast IP address
of 255.255.255.255, and will transmit the packets as Ethernet broadcasts. Use of
broadcasts, however, is strongly discouraged.
•
Stream Name: All BBG-1090-TRX-MPEG input and output ports can be assigned a
user-defined name. This name is used to identify the port later when making
connections. Use any descriptive name suitable for your application, or accept the
default.
•
NULL Padding: This setting controls whether or not NULL packets are transmitted,
making the stream completely CBR. IP networks are inherently VBR, and do not require
NULL packets (which carry no information). However, the decoders may need them.
The following is a good set of rules for deciding whether or not to send NULL packets:
o
If all your decoders are consumer IP set-top boxes or PCs running software
decoders, NULL packets can be disabled.
o
If your decoders include professional IRDs, NULL packets must be enabled. The
great majority of professional IRDs will not work without them.
o
If you are generating an MPTS, enable NULL packets. An MPTS without NULL
packets is technically illegal as per ISO/IEC 13818-1, but some systems support
it.
o
If you are not sure about what kind of decoder will be receiving the stream, enable
NULL packets.
This control offers the following options:
o
Disabled: NULL packets are disabled and will not be transmitted. This will
cause the stream to be somewhat VBR, even if the transcoder is set to CBR mode.
o
Enabled – Automatic Rate: This setting enables NULL packets, but the bit rate
is automatically set by the BBG-1090-TRX-MPEG to the minimum suitable
value. If you later reconfigure inputs connected to this stream, the rate will be
automatically adjusted.
o
Enabled – Manual Rate: This setting allows you to specify the overall stream bit
rate. If you specify the bit rate, it must be high enough to support the connected
inputs. Specifying a rate that is not high enough will cause the IP Output to drop
packets. Note that if this option is selected, the IP Output will be transmitting
continuously at the selected bit rate, regardless of connections or the state of the
transcoders. If there is no connection to the IP Output, it will transmit only
NULL packets; if there are connections and the transcoders are stopped, it will
transmit NULL packets plus (P)SI tables.
•
Transport Stream ID: Enter the desired Transport Stream ID for the port. This
value comes out in the Program Allocation Table (PAT).
•
Pass PMT Changes: This checkbox controls whether PMT descriptor changes from
the connected programs are propagated to the output PMT for this port. This box
defaults to checked, and in most cases it should be left checked. Only uncheck it if
you want to isolate the devices downstream of the transcoder from table changes.
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