I'm just curious as to how AE estimates time remaining.
I am doing days of rendering and sometimes the estimations are no where near the actual. This maybe because I have some of the animation is giving me the "incompatible composition multi processing off" message but not all. The activity monitor shows various CPU usages as the render moves past problem areas. But on a good "no problem" render, how good are estimations? How are they calculated? For instance I am rendering now and I have 4 hs to go yet I know that in a few frames the rest of the movie is just a simple credit roll, and it will zoom on when it gets there.
I'm sure someone can give a more detailed answer and correct me if I'm wrong, but for now ... my understanding is that AE estimates remaining render time based on the currently rendering frame(s), which is why the etimates can be pretty inaccurate ... it's basically assuming that every frame thereafter is the same as the current and will, therefore, take an equal amount of time to render.
So, as you've observed, if the current frame has tons of effetcs, masks, motion blur, etc., rendering slows down considerably and remaining time goes way up, but when it gets to relatively simple frames, rendering speeds up considerably and remaining time drops.