Constant-framerate movie generation via lockstep physics/render?

I would like to create a movie from jme3 at 30fps, and I don’t care how long it takes in terms of user time. Can I cause the screen to be rendered in full once and only once after every physics tick, to achieve an even fixed framerate for my video? If I make such a “capture screen and send to video encoder” function, where would be the most reasonable place to put it–in the .update method of SimpleApplication, or in the .physicsTick method of a PhysicsTickListener, or somewhere else entirely?

thanks in advance.


–Robert McIntyre