Quick Description of Modules (PiTiVi) - and do I see them used-

Core

GLib
low-level - Provides us with the implementation of fundamental types and algorithms. It is a base upon which, everything is constructed.
-In PiTiVi, I see the GLib basic types (gboolean, gchar, gint, gfloat, gdouble etc)-

GObject
With the GObject, GLib provides us with the implementation of an object-oriented framework for C.
-In PiTiVi, I see the gobject functions (http://www.pygtk.org/pygtk2reference/gobject-functions.html)-

GStreamer
A multimedia framework that allows us to do anything multimedia-related. It is very flexible and uses elements
that are packaged in the form of plugins.
These elements can be codecs/demuxers/lmuxer/effects etc.
One set of these plugins are the GNonLin plugins, which are the ones who implement anything related to the logic
of video editing in GStreamer. Mainly, handle the timing of reading different multimedia files.

GES (GStreamer Editing Services)
A library created on top of GNonLin plugins, making the use of GNonLin plugins easier to use. It wraps the
GNonLin elements by offering an API of higher level.

In Pitivi, the GNonLin plugins were used directly, up to now and this is why the porting to GES will facilitate
a lot the design of the project.
So, we are using GStreamer via GES and the most objects used are GES ones (even if they come from GStreamer classes).

UI

GTK+
Toolkit for creating graphical user interfaces. Providing standard widgets and event handling. Based also in GLib.

GooCanvas
One of GTK+ widgets, used for drawing.

All of these components are based in GLib and communicate through it and its signals.


So, if I just want to add quickly GES in the PiTiVi' s wiki diagram (https://wiki.pitivi.org/wiki/Architecture), I would add it here: