Lock Autofocus When Live
If your video appears to be "popping" your focus might be going in and out. Here is a simple solution to that issue. First navigate to the Camera Control tab.
At the very bottom, toggle the slider for "Lock Autofocus When Live" to on.
Now when you send a source live, you will notice that the "AF" in the top middle will be turned off. This is the autofocus function, with this disabled, your camera will no longer "pop" in and out.