undefined reference to `gst_discoverer_*` and others

[Harry McKame]

While linking, I get "undefined reference" messages for all functions named `gst_discoverer_*` and also to the following:
gst_video_info_from_caps, gst_video_overlay_expose.

I'm porting from Windows, where my application works, to Kubuntu 16.10 with Gstreamer 1.8.3, and my link contains `pkg-config --libs gstreamer-1.0` which gives :
-lgstreamer-1.0 -lgobject-2.0 -lglib-2.0.

What am I missing in the link ? Or is it a missing package ?