I have included 2 examples:
ClosedCaptionsEncoder which sends a “Hello World” message through closed captions
ClosedCaptionsSerialTerm which is a serial terminal that prints anything you send over serial to the closed captions
Some caveats: Certain devices constantly are sending a closed caption signal even if there are no captions currently being displayed, and this corrupts any closed caption signal that you would attempt to overlay onto it. This is true for the PS3 composite signal that I tried to overlay a caption on.
It also seems that some tv’s will not accept a closed caption signal from a monochrome signal, and they will require a colorburst for the closed caption to work. This means that you will need to overlay the closed captions onto a color signal for the captions to show up since this library does not produce its own colorburst.
Please try this code out and let me know the results!