Best way of freezing a game for rendering purposes...?

I'm looking to "Freeze" a Unity project once per frame at a given time interval (1/60th of a second), performing a scripted action during each iteration, and of course unfreezing the project.

Like This: Perform normally for 1/60th of a second, Freeze, Perform an action (taking however much time is needed), Unfreeze, Repeat.

The reason for this is so that I may use Unity for rendering a video. Fraps and Nvidia Shadowplay aren't going to cut it due to frame drops and other issues. And then, every solution to this that I've seen so far requires freezing the project AND halting the scripting engine, which isn't what I want.

Also (I doubt this is possible but I want to ask anyway, just in case)...is it possible to capture audio in Unity, from Unity as a source only, for a given time segment?

Like this: "From this moment on, for (x) seconds, capture audio and put it in a buffer when it's done."

Thank you!