captioner

plural captioners

1. One who, or that which, adds captions.

   2007, Ferguson's Careers in Focus: Broadcasting, 3rd edition, Ferguson (imprint), Infobase Publishing, page 123, In the broadcast setting, real-time captioners do not have to produce transcripts, which eliminates the long hours that go along with that aspect of reporting.

   2 more examples

   Some captioners will raise or lower the captions in the center by one row to add one more subtle differentiation, but this is uncommon.

   2004, Gary D. Robson, The Closed Captioning Handbook, Elsevier, page 177

   And how relieved the Ceefax captioners must be that Sir Alex Ferguson still refuses to give interviews to Match of the Day, because of a BBC documentary that upset him.

   2009 September 24, Mark Lawson, “The problems of subtitling the news”, in Guardian