Once the movement or sound has been picked up by the new system, it will simply switch the cameras to make sure that the source of movement or sound is covered by either of the cameras.
A website, Patently Apple, has found the patent application of the technology recently.
The feature would be helpful when a group of users are video chatting with one another. The invention, basically, is all about finding out who is doing the talking and changing the cameras accordingly. Through it, the users would also be able to record the video feed.
While the users would definitely benefit from camera-swapping during FaceTime calls, anybody who is interested in group chatting or video conferencing would find the invention useful.
Google already offers a similar camera switching feature in its Google+ service. Users would, however, do well to note this is just a patent application and that the patent has not been granted yet. Even if granted, patent applications do not always end up in products.
Compared to other similar video chatting apps, FaceTime does not have cross-platform functionality. It means users can only talk to other users if they are present on iOS devices only, not if they are present on Windows PC or Android handsets.