What's the movie (it's recent) where the son is filming a home video and then the dad kills him?

Chops his head off, to be exact. Odd question, I know, it just really
scared me when I watched the trailer but now I have no idea what the
movie is and I want to watch it because it looked really good, not
just because of that scene.

If I remember right, it was assumed to be a zombie movie but it was
actually a vampire movie.