I've had an idea for a feature, but it might sound crazy. I guess this will depend on whether the functionality can be done via Caspar CG and FFMPEG.
I have been seeing that there may be a way to play a video file with the subtitles through FFMPEG and Caspar, so that they are then sent out the SDI video output of a blackmagic card.
I don't know everything in depth, so I thought of publishing it, leaving the idea open here and maybe someone who has more knowledge can contribute something more.
https://casparcgforum.org/t/608-708-closed-captions-out-decklink-sdi/4642/5
https://www.mail-archive.com/ffmpeg-user@ffmpeg.org/msg31131.html
Thanks.