cross compiling win ffmpeg binary, including non-free libraries (like libfdk_aac):

git clone https://github.com/rdp/ffmpeg-windows-build-helpers.git

cd ffmpeg-windows-build-helpers

sudo apt-get install subversion curl texinfo g++ bison flex cvs yasm automake libtool autoconf gcc cmake git make pkg-config zlib1g-dev mercurial unzip pax nasm gperf autogen bzip2 libtool-bin ed -y

./cross_compile_ffmpeg.sh