From Manufacturer
The Closed Caption Option for OnTheAir Video 4 from Softron allows OnTheAir Video 4 to pass closed captioning data. Note that not all sources of captions are supported nor can all destinations receive caption data. In some cases an audio channel may be used. Also note that an I/O card with closed caption support is required. Please refer to the user manual for OnTheAir Video 4 for details.