How to use gst plugins?

2

Problem solved: I was using gstreamer-1.0 tools with gstreamer-0.10 plugins…

with import <nixpkgs> {};

mkShell {
  shellHooks = ''
    export LANG="en_US";
    export GST_PLUGIN_SYSTEM_PATH="${gst_all_1.gst-plugins-base}/lib/gstreamer-1.0/:${gst_all_1.gst-plugins-good}/lib/gstreamer-1.0/"
    export PATH="$PATH:${gst_all_1.gstreamer.dev}/bin"
  '';
}

[nix-shell]$ gst-inspect-1.0 ximagesrc
Factory Details:
  Rank                     none (0)
  Long-name                Ximage video source
  Klass                    Source/Video
...