Hello Kurt,
why don’t you add the CG you need during capturing? An Italian company makes a software that may fit your needs (ivsCapture).
It allows you to print over captured video Time, Date, Timecode, Logo and free text over video (with free text you can type/delete all you need over video without stopping capture). If you’d need it allows you to make realtime color correction and add special effects like blur or glow.
It can capture in a broad range of formats, I don’t use all of its features, so if you need to know more, take a look at its webpage https://www.ivs.it/ENG_H/03prod/02ivs_e/ivsCapture_e.htm
Cheers,
Paolo Strino
Sp Video