Install FFmpeg with libfdk_aac support (For Ubuntu)

install_ffmpeg_libfdkaac.sh

#!/usr/bin/env bash
#Credit to @rafaelbiriba and @dustball

export BASE=/opt

echo "deb http://www.deb-multimedia.org stretch main non-free" >> /etc/apt/sources.list
apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 5C808C2B65558117

apt-get update
apt-get -y install build-essential autoconf automake cmake libtool git \
		wget build-essential ca-certificates \
		openssl libssl-dev yasm \
		libpcre3-dev libtheora-dev \
		libvorbis-dev libvpx-dev libfreetype6-dev \
		libgcr-3-dev autoconf automake build-essential \
        libass-dev libdrm-dev libfreetype6-dev libtheora-dev libtool \
        libvorbis-dev pkg-config texinfo zlib1g-dev \
        libfdk-aac-dev libmp3lame-dev yasm \
		libmp3lame-dev \
		lame checkinstall nasm yasm gnupg2 libass-dev libfreetype6-dev libmp3lame-dev libmp3lame-dev \
		 libsdl2-dev p11-kit libva-dev libvdpau-dev libvorbis-dev libxcb1-dev libxcb-shm0-dev \
		libxcb-xfixes0-dev pkg-config texinfo wget zlib1g-dev  frei0r-plugins-dev gnutls-dev ladspa-sdk libcaca-dev \
		libcdio-paranoia-dev libcodec2-dev libfontconfig1-dev libfreetype6-dev libfribidi-dev libgme-dev libgsm1-dev \
		libjack-dev libmodplug-dev libmp3lame-dev libopencore-amrnb-dev \
		libopencore-amrwb-dev libopenjp2-7-dev libopenmpt-dev libopus-dev libpulse-dev librsvg2-dev \
		librubberband-dev libshine-dev libsmbclient-dev libsnappy-dev libsoxr-dev libspeex-dev libssh-dev libtesseract-dev \
		libtheora-dev libtwolame-dev libv4l-dev libvo-amrwbenc-dev libvorbis-dev libvpx-dev libwavpack-dev libwebp-dev \
		libx264-dev libx265-dev libxvidcore-dev libxml2-dev libzmq3-dev libzvbi-dev liblilv-dev libopenal-dev opencl-dev \
		libjack-dev libavc1394-0 libavc1394-dev libiec61883-0 \
		libiec61883-dev libbluray-dev libbs2b-dev libbs2b0 libdc1394-22 libdc1394-22-dev

mkdir ~/ffmpeg_sources
cd ~/ffmpeg_sources
wget https://ffmpeg.org/releases/ffmpeg-4.2.1.tar.gz
tar xzvf ffmpeg-4.2.1.tar.gz
cd ffmpeg-4.2.1

PKG_CONFIG_PATH="$BASE/ffmpeg_build/lib/pkgconfig"

export PKG_CONFIG_PATH
./configure --prefix="$BASE/ffmpeg_build" \
  --extra-cflags="-I$BASE/ffmpeg_build/include" --extra-ldflags="-L$BASE/ffmpeg_build/lib" \
  --bindir="$BASE/bin" --extra-libs="-ldl" --enable-gpl --enable-libass --enable-libfdk-aac \
  --enable-libmp3lame --enable-nonfree \
  --disable-static --disable-stripping --enable-avisynth \
  --enable-avresample --enable-chromaprint --enable-frei0r \
  --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa \
  --enable-libass --enable-libbluray --enable-libbs2b \
  --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdc1394 \
  --enable-libfontconfig --enable-libfreetype --enable-libfribidi \
  --enable-libgme --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmodplug --enable-libmp3lame \
  --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopenmpt --enable-libopus \
  --enable-libpulse --enable-librsvg --enable-librtmp --enable-librubberband --enable-libshine --enable-libsnappy \
  --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtesseract --enable-libtheora --enable-libtwolame \
  --enable-libv4l2 --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp \
  --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 \
  --enable-nonfree --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-shared --enable-small \
  --enable-version3 --extra-version=0ubuntu0.2 --incdir=/usr/include/x86_64-linux-gnu --libdir=/usr/lib/x86_64-linux-gnu --toolchain=hardened
make -j8
make install
cp ffmpeg /usr/bin/
cp ffprobe /usr/bin/
make distclean
hash -r
ffmpeg 2>&1 | head -n1

Updated to install on ubuntu using solutions provided by @rafaelbiriba and @dustball