how to read thunderbolt?

I just got a Production 4K, and I can tell via Express that it's pushing 4K video out over thunderbolt. I have some questions, though:

1. Does the camera only push the video if Express is running?
2. Is the video always 4K, or only when I start capturing it?
3. How can I capture the video in software from the thunderbolt port? None of my usual software packages appear to see it.

Thanks!

[Tony Rivera]

1. You should be able to capture with other applications if it will recognize the device. Keep in mind you can only have one capture application open at a time.

2. The image you're capturing will be however you set it from start to finish.

3. Referenced this is the first answer. If it sees it as a camera/source, you should be able to capture if the software/application recognizes the product.

I've tried that, and the device is not being recognized by either opencv or VLC, although both of them claim to be able to work with thunderbolt cameras.

I suspect that the camera is not putting the information out to the thunderbolt port by default, and I don't know how to get it to start doing that. Of course, Media Express can tell the camera to push information to the thunderbolt port, but by that point, Media Express has grabbed the port and no other process can examine it.

Does that make sense? What I'd really like is an API of some kind to tell the camera to start pushing the image data to the thunderbolt port.

Thanks!