$ /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
If you haven't installed Xcode yet, you will need to hit the following command.
$ xcode-select --install
or
$ sudo xcode-select --install
$ brew install ffmpeg
If you are a windows user, please check this site(https://www.ffmpeg.org/download.html).