I know the Decklink studio does live SD keying but I have a few questions.
1. Our footage is HD-SDI, does the decklink card down convert and then key? SD monitoring is fine, I just need to know if the originating source can be HD or if we have to rent an additional HD -> SD inline converter.
2. How is the background footage added? I assume there is some kind of decklink software that will help feed it out? It will be still frames of 3d backgrounds.
3. How taxing is this on a computer system? I'll be doing some initial color correction in Red CineX and doing file transfers as DIT. If the decklink card carries all the weight, great, if not then I'll run a second dedicated tower.
I'm supposing that you want to make an internal key, without using an external Down Stream Keyer (you have to add a graphic file with alpha channel to a background coming from an external video source).
I'm not sure about point 1. The Studio has an always active downconverter on the second output (the one used for key), that should make the job, but I never tried that setup.
The Desktop Video software installs the software "Blackmagic Design LiveKey". If you have to change the overlay graphics during the show, I suggest you to make extensive tests, since I remember that it is not so fast and clean to change them.
The sofware doesn't take many system resources.
Hope it helps,