Grass Valley Imagestore 750 v.2.0.1 - Manual (Page 174)

Front Panel Operations Imagestore 750 User Manual
Page 174 Miranda Technologies Inc.
Pass Close Cap
Close caption information is usually passed through the Imagestore whatever
this particular option is set to. The reason that the option exists is that when
the standard is set as NTSC (525), close caption information is found within
the active picture (lines 20/21), and so it will be destroyed when graphics are
keyed over these lines.
When this option is enabled the Imagestore ensures that the close caption
information is preserved if graphics are keyed over lines 20/21. Disabling the
option instructs the keyers/mixers to treat these lines as part of the active
picture so that they may be keyed over.
On HD standards, close caption is contained in line 9 – which is outside the
active picture. Since this is never processed by the keyers the close caption
information is preserved whatever the option selected.
Please note that when SDI picture is routed to a DVE, the close caption
information may be visible at the top of the DVE window. To avoid this
problem it is recommended that all DVE sequences be cropped by 2.5% at
the top to remove this undesirable effect.