Error: libfdk_aac must be installed

You can install ffmpeg with that encoding library like so:

brew install ffmpeg --with-fdk-aac

First try

brew install fdk-aac

Failing that you can compile like I do

git clone git://github.com/mstorsjo/fdk-aac
cd fdk-aac
autoreconf -i
./configure
make install

Example

homebrew-ffmpeg

A few FFmpeg contributors and community members created a new Homebrew tap*, homebrew-ffmpeg, that includes many options. This is in response to the removal of options from the core Homebrew FFmpeg formulae.

1. Uninstall ffmpeg you installed it from Homebrew core:

   brew uninstall ffmpeg
   

2. Enable the repository:

   brew tap homebrew-ffmpeg/ffmpeg
   

3. View available options (optional):

   brew options homebrew-ffmpeg/ffmpeg/ffmpeg
   

4. Install ffmpeg with the libfdk-aac AAC encoder:

   brew install homebrew-ffmpeg/ffmpeg/ffmpeg --with-fdk-aac --HEAD
   

See homebrew-ffmpeg and FFmpeg Wiki: macOS for more info.

_{* Note that this tap is not from the FFmpeg Project itself.}