Main trick is that ffmpeg is not really a command line tool. It's a set of libraries - libav* - built in C which lets you do absolutely everything you want with

Main trick is that ffmpeg is not really a command line tool. It's a set of libraries - libav* - built in C which lets you do absolutely everything you want with video/media files (and somewhat less successfully, with streaming data too, while for modern applications such as webrtc, ffmpeg sucks). Command line tool is just a (rather lame) wrapper for (some) of those features.