What does the black rectangle clipper when filming films and movies actually do? Why do they need one at all?

Question

I always wondered this

In: 133

Answer 1

High-end cameras are often *just* the cameras, which is fine because an included microphone would be bad for audio quality. You’d want to use a separate, high quality mic for good audio anyway. You may also have multiple mics.

Since the camera and mics are separate, the video and audio aren’t automatically synced like they are with consumer level cameras. They have to be synced manually during the edit. The sharp movement and clap makes it easier to sync.