28
EMA x08/407
Part N
o
: 917x.xx
ENCODER/ MULTIPLEXER
ASI / SDI/ A/V
→
ASI(TS) & IP(TS)
ASI / HDMI
→
ASI(TS) & IP(TS)
A
LINE
Note:
The SID/ PID for the slots configured (the programs and channels) is automatically allocated according to a fixed pattern. Inserting
details of the device in the cascade and the number of the cascade ensures that the values will not overlap. If “outside” transport
streams are being processed at the ASI input port, care must be taken to ensure that if the SID/ PIDs of any external and internal
program streams overlap, the internal program streams have priority. Any “external” program streams with the same names will be
blocked at a filter and not fed into the output port.
Operating several cascades within a network (a head end)
To get unique service ID‘s if there are several cascades in one head end, an offset is automatically added for the parameter “cascade
number within network” (CN
o
):
Cascade N
o
1
2
3
4
5
6
7
8
Offset
0x00
0x04
0x08
0x0C
0x80
0x84
0x88
0x8C
Table 4: Offset for the service ID‘s if several cascades are operated in a network
3.3.5 Transport stream bit rate (TS out bit rate), system bit rate
The transport stream bit rate at the ASI output port can be set in the range between 1,024 kbps and 214 Mbps with steps of 1 kbps.
The output bit rate can be selected independently of the input bit rate at the ASI input port. However, care must be taken to ensure that
the entire volume of data is transmitted, including the DVB channels generated additionally by the EMA device. It should be noted that
the transport stream at the ASI input may contain components with a fluctuating data rate. When estimating the bandwidth which will be
necessary for the transmission of newly generated programs, this should be borne in mind.
The bit rate (“TS-Out bit rate”) is selected in the configuration settings under “Channel Mux“.
For the EMA device, the maximum “TS Out Bit Rate“ possible is 214 Mbps. When deciding the “TS Out Bit Rate“ it is necessary
and important to check what is the maximum transport stream bit rate which can be processed or forwarded by succeeding
components such as modulators and upconverters.
The bandwidth (bit rate) which is available can be distributed across the channels generated by the EMA device in any proportions
de-sired. The more channels are transmitted, the lower is the available system bit rate (slot bandwidth) for each channel. Whenever
individual settings are made, care should be taken to ensure that the figures entered into the configuration mask make sense.
Configuration of the system bit rates and “TS-Out Bit Rate”, the output bit rate
When delivered and if reset is carried out with firmware, the system bit rates (slot bandwidth) of each channel will be set to 6 Mbps. This
setting should be seen simply as an upper limit and can be varied according to the content of the data being transmitted. It is possible to
adjust the figures for each channel according to need. The “TS-Out Bit Rate”, which is the data output rate, is preset to 38 Mbps, which
gives enough scope for reliable operation as long as the “ASI Main IN”, the input port, is deactivated. The output rate must be decided
in relation to the content being added, with a safety margin of at least 10 per cent, since it is not possible definitely to exclude swings in
the data rate taking it over the upper limit.
Examples of estimation of the “TS-Out Bit Rate”, the output bit rate
Example 1: Single device with 4 encoders
“ASI Main IN“ = “OFF“
The encoder input ports A ... D employ the following system bit rates: 3x 6 Mbps and 1x 10 Mbps, total
28
Mbps
This allocation, including the necessary
10%
reserve for safety, gives a figure of
31
Mbps (minimum) to be set as the data output rate at
the output port.
Example 2: Single device with 4 encoders and an “ASI Main IN“
“ASI Main IN“ = “MUX with intern“
Here the incoming data stream has a bit rate of 50 Mbps, and 36 Mbps are used for the transport of the data. 14 Mbps are filled with
“empty packets”.
The encoder input ports A ... D employ the following system bit rates: 2x 4 Mbps and 2x 8 Mbps, total
24
Mbps
36+24=
60
, plus
10%
safety margin, so that the data output rate at the output port is
66
Mbps (minimum).