EEG 491 Series Manual page 22

HD491 Smart Encoder
Begin PassThru Mode
End PassThru Mode
<CTRL+A>3 [Pairing] [Field] <ENTER>
<CTRL+C>
Displayed as PTHRU. When a port enters the command to begin
PassThru for a field, caption data received through that port will replace
upstream caption data for that field. PassThru mode is for use with
complete CEA-608 formatted data streams, including control and
formatting codes, such as would be provided by captioning software
packages. If PassThru is engaged but no valid data is being entered, pairs
of null data bytes (80h 80h) will be inserted into output signals. When
PassThru mode is ended, the field will return to upstream Regeneration.
 Field specifies which NTSC field the locally entered caption data is
intended for. Field 1 (enter as F1) is for primary language captioning
and text, and Field 2 (F2) is for secondary language captioning and
text. The parameter defaults to Field 1.
 Pairing can be set using integer values from 1 to 4 corresponding to
differing levels of control code processing. The table below describes
the available levels. If the parameter is not set, the default for field 1
is level 4, and the default for field 2 is level 2.
Control Code Pairing Settings
1 All incoming data is passed. Control byte pairs will not be
automatically aligned, which may lead to missed codes.
2 Field 2 default. Control pairs are identified and delayed if
necessary for correct alignment.
3 Control pairs are corrected for proper alignment and
doubled in Field 1.
4 Field 1 default. Control pairs are corrected for proper
alignment, doubled in Field 1, and non-Line 21 codes are
omitted.
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