Notes about GStreamer Plugin

Ref:
furseal's lair：gstreamer plugin

Note:
_base_init():

• part of GObject system.
  
• The element details are registered with the plugin here.
  
• The _base_init () function should be set for this GObject in the function where
  you register the type with GLib.
  
• It is meant to initialize class and child class properties during each new
  child class creation
  
• In the element _init () function, you create the pad from the pad template that has been registered with the element class in the _base_init () function.

_init():

• Pads are created from its templates in the element’s _init () function using gst_pad_new_from_template ().
  
• It is used to initialise a specific instance of this type.
  
• In the element _init () function, you create the pad from the pad template that has been registered with the element class in the _base_init () function.

_class_init():

• It is used to initialise the class only once (specifying what signals, arguments and virtual functions the class has and setting up global state)