The Link Electronics IEC-787 is a video inserter that recovers signals in the vertical blanking interval. Signals may be lost during video processing such as video compression or overlay and comb filtering. This would include Closed Caption data on line 21, Ghost Cancellation Reference signal on line 19 and other signals in the vertical interval.
Insertion
Any of the lines 10-21 of blanking can be selected by the user; line 21 can be selected and Closed Caption information can be re-inserted for display.