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