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FS1 Installation and Operation Manual — 30.1 Closed Captioning Translator
In standard definition video (525i59.94), closed captioning data is encoded and sent on
line 21 of both fields, using a format defined by the Consumer Electronics Association
standard, CEA-608. This is traditionally called “line 21", “SD”, or “608” captioning, and is
used for analog composite, analog component, and serial digital (SDI) video.
In high definition video, closed captioning is encoded and sent as Vertical Ancillary
(VANC) packets in SDI video, using a format defined by the Consumer Electronics
Association standard CEA-708 (there is no equivalent for analog HD video). This is
traditionally called “HD,” “DTV,” or “708” captioning. The data formatting and encoding
for 708 captions is very different from the data contained in 608 (SD) captioning,
reflecting the added features and capabilities available with the CEA-708 standard.
The FS1 UpConverter automatically translates incoming line 21 captions to CEA-708
format and inserts the VANC packets into the converted HD video stream. This is a
complete translation from CEA-608 format to CEA-708 format (including the
embedded SD captions).
The FS1 DownConverters automatically intercept and reformat the SD caption data in
the incoming CEA-708 VANC packets, and output it on line 21 of the standard definition
outputs.
To pass closed captioning data to the outputs, parameter
31.1 UC Line 21
must also be
set to
Pass
. The FS1 CrossConverters will reformat and pass any incoming CEA-708
VANC packets for the output frame rate.