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755 lines
13 KiB
Text
755 lines
13 KiB
Text
<!-- ##### SECTION Title ##### -->
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GstElement
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<!-- ##### SECTION Short_Description ##### -->
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Base class for all pipeline elements
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<!-- ##### SECTION Long_Description ##### -->
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<para>
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GstElement is the base class needed to construct an element that can be
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used in a GStreamer pipeline. As such, it is not a functional entity, and
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cannot do anything when placed in a pipeline.
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</para>
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<para>
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The name of a GstElement can be get with gst_element_get_name() and set with
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gst_element_set_name(). For speed, GST_ELEMENT_NAME() can be used in the
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core.
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Do not use this in plug-ins or applications in order to retain ABI
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compatibility.
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</para>
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<para>
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All elements have pads (of the type #GstPad). These pads connect to pads on
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other elements. Buffers flow between these connected pads.
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A GstElement has a GList of #GstPad structures for all their input (or sink)
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and output (or source) pads.
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Core and plug-in writers can add and remove pads with gst_element_add_pad()
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and gst_element_remove_pad().
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Application writers can manipulate ghost pads (copies of real pads inside a bin)
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with gst_element_add_ghost_pad() and gst_element_remove_ghost_pad().
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A pad of an element can be retrieved by name with gst_element_get_pad().
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A GList of all pads can be retrieved with gst_element_get_pad_list().
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</para>
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<para>
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Elements can be connected through their pads.
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If the connection is straightforward, use the gst_element_connect()
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convenience function to connect two elements, or gst_element_connect_many()
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for more elements in a row.
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Use gst_element_connect_filtered() to connect two elements constrained by
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a specified set of #GstCaps.
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For finer control, use gst_element_connect_pads() and
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gst_element_connect_pads_filtered() to specify the pads to connect on
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each element by name.
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</para>
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<para>
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Each element has a state (see #GstElementState). You can get and set the state
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of an element with gst_element_get_state() and gst_element_set_state().
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You can wait for an element to change it's state with gst_element_wait_state_change().
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To get a string representation of a #GstElementState, use
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gst_element_statename(), which is a really bad name for what it does
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and should probably be renamed
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to gst_element_state_get_name if we can be bothered to do that.
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</para>
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<para>
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You can get and set a #GstClock on an element using gst_element_get_clock()
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and gst_element_set_clock(). You can wait for the clock to reach a given
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#GstClockTime using gst_element_clock_wait().
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</para>
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<!-- ##### SECTION See_Also ##### -->
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<para>
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#GstElementFactory, #GstPad
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</para>
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<!-- basic object functions -->
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<!-- ##### STRUCT GstElement ##### -->
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<para>
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</para>
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<!-- ##### MACRO gst_element_destroy ##### -->
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<para>
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Destroys the element (without taking the refcount into account).
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An application programmer should use #gst_object_unref instead to dispose
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of an element he doesn't need anymore.
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</para>
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@element: a #GstElement to destroy
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<!-- ##### FUNCTION gst_element_get_name ##### -->
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<para>
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</para>
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@element:
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@Returns:
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<!-- ##### FUNCTION gst_element_set_name ##### -->
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<para>
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</para>
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@element:
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@name:
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<!-- connection -->
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<!-- ##### FUNCTION gst_element_get_factory ##### -->
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<para>
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</para>
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@element:
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@Returns:
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<!-- ##### FUNCTION gst_element_add_pad ##### -->
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<para>
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</para>
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@element:
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@pad:
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<!-- ##### FUNCTION gst_element_remove_pad ##### -->
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<para>
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</para>
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@element:
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@pad:
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<!-- ##### FUNCTION gst_element_add_ghost_pad ##### -->
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<para>
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</para>
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@element:
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@pad:
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@name:
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@Returns:
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<!-- ##### FUNCTION gst_element_remove_ghost_pad ##### -->
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<para>
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</para>
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@element:
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@pad:
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<!-- pad template manipulation -->
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<!-- ##### FUNCTION gst_element_get_pad ##### -->
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<para>
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</para>
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@element:
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@name:
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@Returns: GList of #GstPads
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<!-- ##### FUNCTION gst_element_get_static_pad ##### -->
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<para>
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</para>
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@element:
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@name:
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@Returns:
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<!-- ##### FUNCTION gst_element_get_request_pad ##### -->
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<para>
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</para>
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@element:
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@name:
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@Returns:
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<!-- ##### FUNCTION gst_element_get_pad_list ##### -->
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<para>
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</para>
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@element:
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@Returns:
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<!-- ##### FUNCTION gst_element_get_pad_template_list ##### -->
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<para>
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</para>
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@element:
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@Returns:
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<!-- scheduling -->
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<!-- ##### FUNCTION gst_element_class_add_pad_template ##### -->
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<para>
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</para>
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@klass:
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@templ:
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<!-- # Unused Parameters # -->
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@element:
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<!-- ##### FUNCTION gst_element_connect ##### -->
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<para>
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</para>
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@src:
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@dest:
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@Returns:
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<!-- ##### FUNCTION gst_element_connect_many ##### -->
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<para>
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</para>
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@element_1:
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@element_2:
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@Varargs:
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@Returns:
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<!-- ##### FUNCTION gst_element_connect_filtered ##### -->
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<para>
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</para>
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@src:
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@dest:
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@filtercaps:
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@Returns:
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<!-- ##### FUNCTION gst_element_connect_pads ##### -->
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<para>
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</para>
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@src:
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@srcpadname:
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@dest:
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@destpadname:
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@Returns:
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<!-- ##### FUNCTION gst_element_connect_pads_filtered ##### -->
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<para>
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</para>
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@src:
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@srcpadname:
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@dest:
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@destpadname:
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@filtercaps:
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@Returns:
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<!-- ##### FUNCTION gst_element_disconnect ##### -->
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<para>
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</para>
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@src:
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@dest:
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<!-- # Unused Parameters # -->
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@srcpadname:
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@destpadname:
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<!-- ##### FUNCTION gst_element_disconnect_many ##### -->
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<para>
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</para>
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@element_1:
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@element_2:
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@Varargs:
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<!-- ##### FUNCTION gst_element_disconnect_pads ##### -->
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<para>
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</para>
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@src:
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@srcpadname:
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@dest:
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@destpadname:
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<!-- pad manipulation -->
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<!-- ##### FUNCTION gst_element_get_compatible_pad ##### -->
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<para>
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</para>
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@element:
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@pad:
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@Returns:
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<!-- ##### FUNCTION gst_element_get_compatible_pad_filtered ##### -->
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<para>
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</para>
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@element:
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@pad:
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@filtercaps:
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@Returns:
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<!-- ##### FUNCTION gst_element_set_state ##### -->
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<para>
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</para>
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@element:
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@state:
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@Returns:
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<!-- ##### FUNCTION gst_element_get_state ##### -->
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<para>
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</para>
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@element:
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@Returns:
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<!-- # Unused Parameters # -->
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@elem:
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<!-- ##### FUNCTION gst_element_state_get_name ##### -->
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<para>
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</para>
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@state:
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@Returns:
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<!-- ##### FUNCTION gst_element_wait_state_change ##### -->
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<para>
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</para>
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@element:
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<!-- ##### FUNCTION gst_element_error ##### -->
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<para>
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</para>
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@element:
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@error:
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@Varargs:
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<!-- ##### FUNCTION gst_element_set_eos ##### -->
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<para>
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</para>
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@element:
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<!-- ##### FUNCTION gst_element_interrupt ##### -->
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<para>
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</para>
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@element:
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@Returns:
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<!-- ##### FUNCTION gst_element_yield ##### -->
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<para>
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</para>
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@element:
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<!-- ##### FUNCTION gst_element_get_clock ##### -->
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<para>
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</para>
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@element:
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@Returns:
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<!-- ##### FUNCTION gst_element_set_clock ##### -->
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<para>
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</para>
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@element:
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@clock:
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<!-- ##### FUNCTION gst_element_clock_wait ##### -->
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<para>
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</para>
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@element:
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@clock:
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@time:
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@Returns:
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<!-- ##### USER_FUNCTION GstElementGetClockFunction ##### -->
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<para>
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The function to get the clock from a clock providing element
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</para>
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@element: The element to get the clock of
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@Returns: The clock provided by the element
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<!-- ##### USER_FUNCTION GstElementSetClockFunction ##### -->
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<para>
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The function to set the clock on a clock receiving element.
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</para>
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@element: The element to set the clock on
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@clock: The clock to set on the element
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<!-- ##### FUNCTION gst_element_set_loop_function ##### -->
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<para>
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</para>
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@element:
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@loop:
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<!-- ##### USER_FUNCTION GstElementLoopFunction ##### -->
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<para>
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This function type is used to specify a loop function for the element. It
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is passed the element in question, and is expect to return only in error
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circumstances.
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</para>
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@element: The element in question.
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<!-- ##### FUNCTION gst_element_get_scheduler ##### -->
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<para>
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</para>
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@element:
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@Returns:
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<!-- ##### FUNCTION gst_element_set_scheduler ##### -->
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<para>
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</para>
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@element:
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@sched:
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<!-- ##### FUNCTION gst_element_get_parent ##### -->
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<para>
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</para>
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@element:
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@Returns:
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<!-- ##### FUNCTION gst_element_set_parent ##### -->
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<para>
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</para>
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@element:
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@parent:
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<!-- ##### FUNCTION gst_element_get_managing_bin ##### -->
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<para>
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</para>
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@element:
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@Returns:
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<!-- clocking -->
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<!-- ##### ENUM GstElementState ##### -->
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<para>
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This enum defines the standard states an element may be in. You will normally
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use gst_element_set_state() to change the state of an element.
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</para>
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@GST_STATE_VOID_PENDING:
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@GST_STATE_NULL: Reset the state of an element.
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@GST_STATE_READY: will make the element ready to start processing data. some
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elements might have a non trivial way to initialize themselves.
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@GST_STATE_PAUSED: means there really is data flowing temporary stops the data flow.
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@GST_STATE_PLAYING: means there really is data flowing through the graph.
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<!-- ##### ENUM GstElementStateReturn ##### -->
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<para>
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This enum defines the standard return values that an element
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can return after a state change.
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</para>
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@GST_STATE_FAILURE: the element could not perform the state change
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@GST_STATE_SUCCESS: the element successfully changed its state
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@GST_STATE_ASYNC: the element will asynchronously change its state as soon as possible
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<!-- ##### MACRO GST_NUM_STATES ##### -->
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<para>
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The maximun number of states.
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</para>
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<!-- ##### MACRO GST_STATE ##### -->
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<para>
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This macro returns the current state of the element.
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</para>
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@obj: Element to return state for.
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<!-- ##### MACRO GST_STATE_PENDING ##### -->
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<para>
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This macro returns the currently pending state of the element.
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</para>
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@obj: Element to return the pending state for.
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<!-- ##### MACRO GST_STATE_TRANSITION ##### -->
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<para>
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Returns the state transition this object is going through.
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</para>
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@obj: the Element to return the state transition for
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<!-- ##### MACRO GST_STATE_NULL_TO_READY ##### -->
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<para>
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The Element is going from the NULL state to the READY state.
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</para>
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<!-- ##### MACRO GST_STATE_READY_TO_PAUSED ##### -->
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<para>
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The Element is going from the READY state to the PAUSED state.
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</para>
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<!-- ##### MACRO GST_STATE_PAUSED_TO_READY ##### -->
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<para>
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The Element is going from the PAUSED state to the READY state.
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</para>
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<!-- ##### MACRO GST_STATE_PLAYING_TO_PAUSED ##### -->
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<para>
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The Element is going from the PLAYING state to the PAUSED state.
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</para>
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<!-- ##### MACRO GST_STATE_PAUSED_TO_PLAYING ##### -->
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<para>
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The Element is going from the PAUSED state to the PLAYING state.
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</para>
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<!-- ##### MACRO GST_STATE_READY_TO_NULL ##### -->
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<para>
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The Element is going from the READY state to the NULL state.
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</para>
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<!-- ##### ENUM GstElementFlags ##### -->
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<para>
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This enum defines the standard flags that an element may have.
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</para>
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@GST_ELEMENT_COMPLEX:
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@GST_ELEMENT_DECOUPLED:
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@GST_ELEMENT_THREAD_SUGGESTED:
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@GST_ELEMENT_NO_SEEK:
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@GST_ELEMENT_INFINITE_LOOP:
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@GST_ELEMENT_SCHEDULER_PRIVATE1:
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@GST_ELEMENT_SCHEDULER_PRIVATE2:
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@GST_ELEMENT_NEW_LOOPFUNC:
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@GST_ELEMENT_EVENT_AWARE:
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@GST_ELEMENT_FLAG_LAST:
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<!-- ##### MACRO GST_ELEMENT_IS_THREAD_SUGGESTED ##### -->
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<para>
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Queries whether the Element should be placed in a thread.
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</para>
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@obj: a #GstElement to query
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<!-- ##### MACRO GST_ELEMENT_IS_DECOUPLED ##### -->
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<para>
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Queries if the Element is decoupled.
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</para>
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@obj: a #GstElement to query
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<!-- ##### MACRO GST_ELEMENT_IS_EOS ##### -->
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<para>
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Query wether this element is in the End Of Stream state.
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</para>
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@obj: a #GstElement to query
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<!-- ##### MACRO GST_ELEMENT_IS_EVENT_AWARE ##### -->
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<para>
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Query wether this element can handle events.
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</para>
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@obj: a #GstElement to query
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<!-- ##### MACRO GST_ELEMENT_PARENT ##### -->
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<para>
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Get the parent object of this element.
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</para>
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|
|
|
@obj: a #GstElement to query
|
|
|
|
|
|
<!-- ##### MACRO GST_ELEMENT_NAME ##### -->
|
|
<para>
|
|
Gets the name of this element. Used in the core. Not ABI-compatible.
|
|
</para>
|
|
|
|
@obj: A #GstElement to query
|
|
|
|
|
|
<!-- ##### MACRO GST_ELEMENT_PADS ##### -->
|
|
<para>
|
|
Get the pads of this elements.
|
|
</para>
|
|
|
|
@obj: a #GstElement to query
|
|
|
|
|
|
<!-- ##### MACRO GST_ELEMENT_SCHED ##### -->
|
|
<para>
|
|
Get the scheduler of this element.
|
|
</para>
|
|
|
|
@obj: a #GstElement to query
|
|
|
|
|
|
<!-- ##### MACRO GST_ELEMENT_MANAGER ##### -->
|
|
<para>
|
|
Get the manager of this element.
|
|
</para>
|
|
|
|
@obj: a #GstElement to query
|
|
|
|
|
|
<!-- ##### MACRO GST_ELEMENT_CLOCK ##### -->
|
|
<para>
|
|
Get the clock of this element
|
|
</para>
|
|
|
|
@obj: a #GstElement to query
|
|
|
|
|
|
<!-- ##### SIGNAL GstElement::eos ##### -->
|
|
<para>
|
|
|
|
</para>
|
|
|
|
@gstelement: the object which received the signal.
|
|
|
|
<!-- ##### SIGNAL GstElement::error ##### -->
|
|
<para>
|
|
Is trigered whenever an error occured
|
|
|
|
</para>
|
|
|
|
@gstelement: the object which received the signal.
|
|
@arg1: the error message
|
|
@arg2:
|
|
|
|
<!-- ##### SIGNAL GstElement::new-pad ##### -->
|
|
<para>
|
|
Is trigered whenever a new pad is added to an element
|
|
</para>
|
|
|
|
@gstelement: the object which received the signal.
|
|
@arg1: the new pad that was added
|
|
|
|
<!-- ##### SIGNAL GstElement::pad-removed ##### -->
|
|
<para>
|
|
|
|
</para>
|
|
|
|
@gstelement: the object which received the signal.
|
|
@arg1: The pad that was removed.
|
|
|
|
<!-- ##### SIGNAL GstElement::state-change ##### -->
|
|
<para>
|
|
Is trigered whenever the state of an element changes
|
|
</para>
|
|
|
|
@gstelement: the object which received the signal.
|
|
@arg1: the new state of the object
|
|
@arg2:
|
|
|