usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/pianobar.rb so you have to find formula on your system e.g. Reason for that is pianobar has main ffmpeg in its dependencies than this functional one. I encounter that problem when trying to compile pianobar. So if you use homebrew be sure to stay on whatever version you are comfortable and NEVER EVER upgrade. Not everyone wants to use latest software because unfortunately newer MacoS are buggy and dropped lot of support for stuff. Mojave should always be supported, so for the future using Homebrew will result you won't get support. Also I'm on Mojave and they always give me warning that 'we do not support this version any longer'. If they care too much about licensing it result in bad user experience. Homebrew is shit, they should break the law and offer functional ffmpeg version.

Try to do this - I am installing ffmpeg from separate casks brew upgrade -force homebrew-ffmpeg/ffmpeg/ffmpeg -fetch-HEAD -with-fdk-aac -with-libbluray -with-openh264 -with-srt -with-wavpack -with-webp -with-xvid -with-two-lame -with-opencore-amr -with-librsvg -with-openjpeg -with-speex -with-openssl -with-xvid

Ffmpeg library mac