mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-12-04 23:46:43 +00:00
46 lines
2.1 KiB
Text
46 lines
2.1 KiB
Text
|
So, the method of having a _start() and _stop() function for each element
|
||
|
|
just doesn't scale. In the case of pipeline/thread model with a PLAYING
|
||
|
|
state bit, I have no way of passing a state change all the way down the
|
||
|
|
graph, i.e. a thread sitting inside a supplied bin.
|
||
|
|
|
||
|
|
Proposal is to have a single state-change class function, which gets
|
||
|
|
passed a single argument (no more 'state' going along with RUNNING). This
|
||
|
|
function can be overridden by each element as necessary, but must chain to
|
||
|
|
the parent_class version of it. It does its work, just like [st]et_arg,
|
||
|
|
in a case. It checks for STATE and ~STATE, and does the appropriate
|
||
|
|
steps. All the _start() and _stop() functions get moved into this one, in
|
||
|
|
the GST_STATE_RUNNING and ~GST_STATE_RUNNING cases.
|
||
|
|
|
||
|
|
This allows bins to and derivations thereof to simply pass through any
|
||
|
|
state they don't understand. Meta-elements will also pass through.
|
||
|
|
|
||
|
|
There may need to be some mechanism that provides for setting state on
|
||
|
|
only a certain type. This can be provided as an alternate path supplied
|
||
|
|
by bins. The bin is the one that would do the work in any case. Simply
|
||
|
|
provide class function for bins that does the selective stuff, and a main
|
||
|
|
_bin_ function that calls this class function. The supplied class
|
||
|
|
function for each bin would simply check against the given GtkType before
|
||
|
|
setting its state. Derivations of GstBin would always get it.
|
||
|
|
|
||
|
|
Success chaining (gbooleans) starts to get a little hairier...
|
||
|
|
|
||
|
|
|
||
|
|
Functions:
|
||
|
|
|
||
|
|
gst_element_set_state(element,state) is called by the application to set
|
||
|
|
the state for an element (or bin).
|
||
|
|
|
||
|
|
elementclass->change_state() is the class function that actually does the
|
||
|
|
setting of the state for this element. Any subclass implementation will
|
||
|
|
chain to the parent_class's version.
|
||
|
|
|
||
|
|
gst_element_change_state(element,state) is the Element class's
|
||
|
|
implementation of the change_state() function. It simply sets the state.
|
||
|
|
|
||
|
|
|
||
|
|
gst_bin_set_state_type(element,state,type) is a specialized function for
|
||
|
|
bins only that sets the type only on elements of that type.
|
||
|
|
|
||
|
|
binclass->change_state_type() is the class function that does the
|
||
|
|
selective
|