Cobalt Digital COMPASS 9223 Dual-Channel 3G_HD_SD MPEG-4 Encoder User Manual
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9223-OM (V2.0)
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Stream Name: All 9223 input and output ports can be assigned a user-defined name.
This name is used to identify the stream later when making connections. Use any
descriptive name suitable for your application, or accept the default.
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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 (routing both encoders to the stream), 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 encoder is set to CBR mode.
o
Enabled – Automatic Rate: This setting enables NULL packets, but the bit rate
is automatically set by the 9223 to the minimum suitable value. This is the
recommended setting. If you later reconfigure an encoder 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
encoders (i.e., it must be at least equal to the sum of the encoder Transport Rate,
found in each encoder Status tab). 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 encoders. If there is no connection to the IP
Output, it will transmit only NULL packets; if there are connections and the
encoders are stopped, it will transmit NULL packets plus (P)SI tables.
If the Advanced View is selected, four more parameters are available for configuration: