sudo apt install build-essential

# install sdl2
sudo apt install libsdl2-dev
sudo apt install libgl-dev

# yasm
sudo apt  install yasm

# libfdk-aac
sudo apt install libfdk-aac-dev

# x264
sudo apt install libx264-dev

# vp8/vp9
sudo apt install libvpx-dev

# mp3lame
sudo apt install libmp3lame-dev

# opus
sudo apt install libopus-dev

# v4l
sudo apt install libv4l-dev

# build ffmpeg
tar xavf ffmpeg-4.2.8.tar.bz2
cd ffmpeg-4.2.8/
./configure --enable-gpl --enable-libx264
make
sudo make install

# build pjsip
tar xavf pjproject-2.13.tar.gz
cd pjproject-2.13/
./configure
echo "#define PJMEDIA_HAS_VIDEO    1" > /pjlib/include/pj/config_site.h
make dep
make
sudo make install