docs/random/states.old

OUTDATED
--------

GST States and Transition Rules (graph to follow)
-------------------------------

This should be a map of possible state transitions and what triggers them.

What the states are:
GST_STATE_NEW: a new element has this, if it has nothing set except name.
GST_STATE_INCOMPLETE: any element that has some, but not enough
	information to function is in this state.
GST_STATE_COMPLETE: if the element has enough data, but is not in any kind
	of running or explicitely stopped state.  ready to be used.
GST_STATE_DISCOVERY: anything the element does in this state must be reset
	after discovery.  any data read from sync source must be cached.
GST_STATE_PREROLL: not a lot different from PLAYING, except sinks don't
	render what they're getting.  useful for elements that require
	data to get in sync, such as an MPEG video decoder that needs
	IBBPBB before starting at the next P.
GST_STATE_RUNNING: this is the normal state of the pipeline, where data
	goes all the way through the pipeline normally.
GST_STATE_STOPPED: an explicit stop state, different from COMPLETE in that
	the state doesn't get reset.


NULL -> GST_STATE_NEW
	creating an element (gst_*_new*)

GST_STATE_NEW -> GST_STATE_INCOMPLETE
	setting anything in the element that isn't sufficient to bring it
	to a useful state (gst_object_set)

GST_STATE_INCOMPLETE -> GST_STATE_COMPLETE
	setting whatever the last bit of info the element was looking for
	(gst_object_set)

GST_STATE_COMPLETE -> GST_STATE_INCOMPLETE
	changing anything that invalidates the complete state of the element

GST_STATE_COMPLETE -> GST_STATE_DISCOVERY
	setting the state to DISCOVERY
	[ used for autoplug ]

GST_STATE_DISCOVERY -> GST_STATE_COMPLETE
	setting the state !DISCOVERY
	[ used when autoplug is over ]

GST_STATE_DISCOVERY -> GST_STATE_PREROLL
	setting the state to PREROLL
	[ you can go straight to preroll from discovery if you want ]

GST_STATE_DISCOVERY -> GST_STATE_RUNNING
	setting the state to RUNNING
	[ you can even go straight to running from preroll ]

GST_STATE_DISCOVERY -> GST_STATE_STOPPED
	setting the state to STOPPED
	[ normally you'd go from discovery to stopped when you load a src ]

GST_STATE_PREROLL -> GST_STATE_RUNNING
	setting the state to RUNNING
	[ preroll generally leads straight to running, as in above ]

GST_STATE_PREROLL -> GST_STATE_STOPPED
	setting the state to STOPPED
	[ it is possible to go to stopped, i.e load file@time ]

GST_STATE_RUNNING -> GST_STATE_PREROLL
	setting the state to PREROLL
	[ unsure if you'd need this state, you'd go to stopped first ]

GST_STATE_RUNNING -> GST_STATE_STOPPED
	setting the state to STOPPED
	[ pause. ]

GST_STATE_STOPPED -> GST_STATE_PREROLL
	setting the state to PREROLL
	[ if you seek to intermediate time while stopped, you'd preroll to
	  prepare to start running again immediately ]

GST_STATE_STOPPED -> GST_STATE_RUNNING
	setting the state to RUNNING