Sets our main struct and passes it to the parent class.
Get the main Gtk struct
the main Gtk struct as a void*
Iterates the supplied list of UUIDs and checks the GstRegistry for an element that supports one of the supplied UUIDs. If more than one element matches, the system ID of the highest ranked element is selected.
the main Gtk struct
Metadata type that holds information about a sample from a protection-protected track, including the information needed to decrypt it (if it is encrypted).