I do not know how others are supposed to know that to compile some tutorials you need to add gstreamer-audio-1.0, gstreamer-pbutils-1.0 (and possibly more) to pkg-config. I had to ask on IRC. So maybe it is a good idea to add "please compile with `pkg-config gstreamer-audio-1.0` clause to the top of the tutorial or maybe in the documentation webpage.

#include <gst/audio/audio.h>  --- requires gstreamer-audio-1.0

#include <gst/pbutils/pbutils.h> --- requires gstreamer-pbutils-1.0