Playback states describe the state of an element or a pipeline. There are following playback states:

• :stopped - Idle. No resources should be initialized nor allocated.
• :prepared - Ready for processing data. All necessary resources should be allocated and initialized.
• :playing - Data is being processed.

Every playback state change is done step-by-step meaning that when going from :stopped to :playing there are 2 state changes (:stopped -> :prepared and :prepared -> :playing) resulting in invocation of proper callbacks (such as Membrane.Element.Base.handle_stopped_to_prepared/2 or c:Membrane.Parent.handle_prepared_to_playing/2)