③ GStreamer Elements

The GstDlsTransform class serves as shim between C++ interface and GStreamer and used to automatically register any C++ element as GStreamer element. This shim is responsible for all interactions with GStreamer, GLib type registrations, and wrapping Intel® DL Streamer C++ objects into GStreamer/GLib objects.

The following class diagram shows how GstDlsTransform connected to C++ interfaces and GStreamer interfaces. GStreamer independent blocks colored in blue and GStreamer dependent blocks colored in gray.

C++ interfaces and classes

Register C++ element as GStreamer element

To register C++ element with GStreamer, register_elements_gst_plugin function is used. It should be called from plugin_init function of GStreamer plugin, here’s an example:

static gboolean plugin_init(GstPlugin *plugin) {
  return register_elements_gst_plugin(tensor_postproc_label, plugin);
}

How C++ element works as GStreamer element

In case of using C++ element in GStreamer pipeline, the shim GstDlsTransform is responsible for element creation and operation. The following sequence diagram shows how GstDlsTransform communicates with GStreamer and an C++ element. It doesn’t show all possible calls, but only the main ones.

High-level sequence diagram of element creation and operation