2 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
3 * 2004 Wim Taymans <wim@fluendo.com>
5 * gstelement.c: The base element, all elements derive from this
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Library General Public
9 * License as published by the Free Software Foundation; either
10 * version 2 of the License, or (at your option) any later version.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Library General Public License for more details.
17 * You should have received a copy of the GNU Library General Public
18 * License along with this library; if not, write to the
19 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 * Boston, MA 02111-1307, USA.
25 * @short_description: Abstract base class for all pipeline elements
26 * @see_also: #GstElementFactory, #GstPad
28 * GstElement is the abstract base class needed to construct an element that
29 * can be used in a GStreamer pipeline. Please refer to the plugin writers
30 * guide for more information on creating #GstElement subclasses.
32 * The name of a #GstElement can be get with gst_element_get_name() and set with
33 * gst_element_set_name(). For speed, GST_ELEMENT_NAME() can be used in the
34 * core when using the appropriate locking. Do not use this in plug-ins or
35 * applications in order to retain ABI compatibility.
37 * All elements have pads (of the type #GstPad). These pads link to pads on
38 * other elements. #GstBuffer flow between these linked pads.
39 * A #GstElement has a #GList of #GstPad structures for all their input (or sink)
40 * and output (or source) pads.
41 * Core and plug-in writers can add and remove pads with gst_element_add_pad()
42 * and gst_element_remove_pad().
44 * A pad of an element can be retrieved by name with gst_element_get_pad().
45 * An iterator of all pads can be retrieved with gst_element_iterate_pads().
47 * Elements can be linked through their pads.
48 * If the link is straightforward, use the gst_element_link()
49 * convenience function to link two elements, or gst_element_link_many()
50 * for more elements in a row.
51 * Use gst_element_link_filtered() to link two elements constrained by
52 * a specified set of #GstCaps.
53 * For finer control, use gst_element_link_pads() and
54 * gst_element_link_pads_filtered() to specify the pads to link on
55 * each element by name.
57 * Each element has a state (see #GstState). You can get and set the state
58 * of an element with gst_element_get_state() and gst_element_set_state().
59 * Setting a state triggers a #GstStateChange. To get a string representation
60 * of a #GstState, use gst_element_state_get_name().
62 * You can get and set a #GstClock on an element using gst_element_get_clock()
63 * and gst_element_set_clock().
64 * Some elements can provide a clock for the pipeline if
65 * gst_element_provides_clock() returns %TRUE. With the
66 * gst_element_provide_clock() method one can retrieve the clock provided by
68 * Not all elements require a clock to operate correctly. If
69 * gst_element_requires_clock() returns %TRUE, a clock should be set on the
70 * element with gst_element_set_clock().
72 * Note that clock slection and distribution is normally handled by the
73 * toplevel #GstPipeline so the clock functions are only to be used in very
74 * specific situations.
76 * Last reviewed on 2009-05-29 (0.10.24)
79 #include "gst_private.h"
82 #include <gobject/gvaluecollector.h>
84 #include "gstelement.h"
85 #include "gstelementdetails.h"
86 #include "gstenumtypes.h"
88 #include "gstmarshal.h"
94 #include "gst-i18n-lib.h"
96 /* Element signals and args */
112 #ifdef GST_DISABLE_DEPRECATED
113 #if !defined(GST_DISABLE_LOADSAVE) && !defined(GST_REMOVE_DEPRECATED)
114 #include <libxml/parser.h>
115 xmlNodePtr gst_object_save_thyself (const GstObject * object,
117 GstObject *gst_object_load_thyself (xmlNodePtr parent);
118 void gst_pad_load_and_link (xmlNodePtr self, GstObject * parent);
122 static void gst_element_class_init (GstElementClass * klass);
123 static void gst_element_init (GstElement * element);
124 static void gst_element_base_class_init (gpointer g_class);
125 static void gst_element_base_class_finalize (gpointer g_class);
127 static void gst_element_dispose (GObject * object);
128 static void gst_element_finalize (GObject * object);
130 static GstStateChangeReturn gst_element_change_state_func (GstElement * element,
131 GstStateChange transition);
132 static GstStateChangeReturn gst_element_get_state_func (GstElement * element,
133 GstState * state, GstState * pending, GstClockTime timeout);
134 static GstStateChangeReturn gst_element_set_state_func (GstElement * element,
136 static void gst_element_set_bus_func (GstElement * element, GstBus * bus);
138 static gboolean gst_element_default_send_event (GstElement * element,
140 static gboolean gst_element_default_query (GstElement * element,
143 static GstPadTemplate
144 * gst_element_class_get_request_pad_template (GstElementClass *
145 element_class, const gchar * name);
147 #if !defined(GST_DISABLE_LOADSAVE) && !defined(GST_REMOVE_DEPRECATED)
148 static xmlNodePtr gst_element_save_thyself (GstObject * object,
150 static void gst_element_restore_thyself (GstObject * parent, xmlNodePtr self);
153 static GstObjectClass *parent_class = NULL;
154 static guint gst_element_signals[LAST_SIGNAL] = { 0 };
156 /* this is used in gstelementfactory.c:gst_element_register() */
157 GQuark _gst_elementclass_factory = 0;
160 gst_element_get_type (void)
162 static volatile gsize gst_element_type = 0;
164 if (g_once_init_enter (&gst_element_type)) {
166 static const GTypeInfo element_info = {
167 sizeof (GstElementClass),
168 gst_element_base_class_init,
169 gst_element_base_class_finalize,
170 (GClassInitFunc) gst_element_class_init,
175 (GInstanceInitFunc) gst_element_init,
179 _type = g_type_register_static (GST_TYPE_OBJECT, "GstElement",
180 &element_info, G_TYPE_FLAG_ABSTRACT);
182 _gst_elementclass_factory =
183 g_quark_from_static_string ("GST_ELEMENTCLASS_FACTORY");
184 g_once_init_leave (&gst_element_type, _type);
186 return gst_element_type;
190 gst_element_class_init (GstElementClass * klass)
192 GObjectClass *gobject_class;
193 GstObjectClass *gstobject_class;
195 gobject_class = (GObjectClass *) klass;
196 gstobject_class = (GstObjectClass *) klass;
198 parent_class = g_type_class_peek_parent (klass);
201 * GstElement::pad-added:
202 * @gstelement: the object which received the signal
203 * @new_pad: the pad that has been added
205 * a new #GstPad has been added to the element. Note that this signal will
206 * usually be emitted from the context of the streaming thread. Also keep in
207 * mind that if you add new elements to the pipeline in the signal handler
208 * you will need to set them to the desired target state with
209 * gst_element_set_state() or gst_element_sync_state_with_parent().
211 gst_element_signals[PAD_ADDED] =
212 g_signal_new ("pad-added", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
213 G_STRUCT_OFFSET (GstElementClass, pad_added), NULL, NULL,
214 gst_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GST_TYPE_PAD);
216 * GstElement::pad-removed:
217 * @gstelement: the object which received the signal
218 * @old_pad: the pad that has been removed
220 * a #GstPad has been removed from the element
222 gst_element_signals[PAD_REMOVED] =
223 g_signal_new ("pad-removed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
224 G_STRUCT_OFFSET (GstElementClass, pad_removed), NULL, NULL,
225 gst_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GST_TYPE_PAD);
227 * GstElement::no-more-pads:
228 * @gstelement: the object which received the signal
230 * This signals that the element will not generate more dynamic pads.
231 * Note that this signal will usually be emitted from the context of
232 * the streaming thread.
234 gst_element_signals[NO_MORE_PADS] =
235 g_signal_new ("no-more-pads", G_TYPE_FROM_CLASS (klass),
236 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstElementClass, no_more_pads), NULL,
237 NULL, gst_marshal_VOID__VOID, G_TYPE_NONE, 0);
239 gobject_class->dispose = gst_element_dispose;
240 gobject_class->finalize = gst_element_finalize;
242 #if !defined(GST_DISABLE_LOADSAVE) && !defined(GST_REMOVE_DEPRECATED)
243 gstobject_class->save_thyself =
244 ((gpointer (*)(GstObject * object,
245 gpointer self)) * GST_DEBUG_FUNCPTR (gst_element_save_thyself));
246 gstobject_class->restore_thyself =
247 ((void (*)(GstObject * object,
248 gpointer self)) *GST_DEBUG_FUNCPTR (gst_element_restore_thyself));
251 klass->change_state = GST_DEBUG_FUNCPTR (gst_element_change_state_func);
252 klass->set_state = GST_DEBUG_FUNCPTR (gst_element_set_state_func);
253 klass->get_state = GST_DEBUG_FUNCPTR (gst_element_get_state_func);
254 klass->set_bus = GST_DEBUG_FUNCPTR (gst_element_set_bus_func);
255 klass->query = GST_DEBUG_FUNCPTR (gst_element_default_query);
256 klass->send_event = GST_DEBUG_FUNCPTR (gst_element_default_send_event);
257 klass->numpadtemplates = 0;
259 klass->elementfactory = NULL;
263 gst_element_base_class_init (gpointer g_class)
265 GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
267 /* FIXME 0.11: Copy the element details and instead of clearing the
268 * pad template list copy the list and increase the refcount of
269 * the pad templates by one.
271 * This will make it possible to add pad templates and set element
272 * details in the class_init functions and is the real GObject way
274 * See http://bugzilla.gnome.org/show_bug.cgi?id=491501
276 memset (&element_class->details, 0, sizeof (GstElementDetails));
277 element_class->meta_data = NULL;
278 element_class->padtemplates = NULL;
280 /* set the factory, see gst_element_register() */
281 element_class->elementfactory =
282 g_type_get_qdata (G_TYPE_FROM_CLASS (element_class),
283 _gst_elementclass_factory);
284 GST_DEBUG ("type %s : factory %p", G_OBJECT_CLASS_NAME (element_class),
285 element_class->elementfactory);
289 gst_element_base_class_finalize (gpointer g_class)
291 GstElementClass *klass = GST_ELEMENT_CLASS (g_class);
293 g_list_foreach (klass->padtemplates, (GFunc) gst_object_unref, NULL);
294 g_list_free (klass->padtemplates);
295 __gst_element_details_clear (&klass->details);
296 if (klass->meta_data) {
297 gst_structure_free (klass->meta_data);
298 klass->meta_data = NULL;
303 gst_element_init (GstElement * element)
305 GST_STATE (element) = GST_STATE_NULL;
306 GST_STATE_TARGET (element) = GST_STATE_NULL;
307 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
308 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
309 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
311 /* FIXME 0.11: Store this directly in the instance struct */
312 element->state_lock = g_slice_new (GStaticRecMutex);
313 g_static_rec_mutex_init (element->state_lock);
314 element->state_cond = g_cond_new ();
318 * gst_element_release_request_pad:
319 * @element: a #GstElement to release the request pad of.
320 * @pad: the #GstPad to release.
322 * Makes the element free the previously requested pad as obtained
323 * with gst_element_get_request_pad().
325 * This does not unref the pad. If the pad was created by using
326 * gst_element_get_request_pad(), gst_element_release_request_pad() needs to be
327 * followed by gst_object_unref() to free the @pad.
332 gst_element_release_request_pad (GstElement * element, GstPad * pad)
334 GstElementClass *oclass;
336 g_return_if_fail (GST_IS_ELEMENT (element));
337 g_return_if_fail (GST_IS_PAD (pad));
339 oclass = GST_ELEMENT_GET_CLASS (element);
341 /* if the element implements a custom release function we call that, else we
342 * simply remove the pad from the element */
343 if (oclass->release_pad)
344 (oclass->release_pad) (element, pad);
346 gst_element_remove_pad (element, pad);
350 * gst_element_requires_clock:
351 * @element: a #GstElement to query
353 * Query if the element requires a clock.
355 * Returns: %TRUE if the element requires a clock
360 gst_element_requires_clock (GstElement * element)
364 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
366 result = (GST_ELEMENT_GET_CLASS (element)->set_clock != NULL);
372 * gst_element_provides_clock:
373 * @element: a #GstElement to query
375 * Query if the element provides a clock. A #GstClock provided by an
376 * element can be used as the global #GstClock for the pipeline.
377 * An element that can provide a clock is only required to do so in the PAUSED
378 * state, this means when it is fully negotiated and has allocated the resources
379 * to operate the clock.
381 * Returns: %TRUE if the element provides a clock
386 gst_element_provides_clock (GstElement * element)
390 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
392 result = (GST_ELEMENT_GET_CLASS (element)->provide_clock != NULL);
398 * gst_element_provide_clock:
399 * @element: a #GstElement to query
401 * Get the clock provided by the given element.
402 * <note>An element is only required to provide a clock in the PAUSED
403 * state. Some elements can provide a clock in other states.</note>
405 * Returns: (transfer full): the GstClock provided by the element or %NULL
406 * if no clock could be provided. Unref after usage.
411 gst_element_provide_clock (GstElement * element)
413 GstClock *result = NULL;
414 GstElementClass *oclass;
416 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
418 oclass = GST_ELEMENT_GET_CLASS (element);
420 if (oclass->provide_clock)
421 result = oclass->provide_clock (element);
427 * gst_element_set_clock:
428 * @element: a #GstElement to set the clock for.
429 * @clock: the #GstClock to set for the element.
431 * Sets the clock for the element. This function increases the
432 * refcount on the clock. Any previously set clock on the object
435 * Returns: %TRUE if the element accepted the clock. An element can refuse a
436 * clock when it, for example, is not able to slave its internal clock to the
437 * @clock or when it requires a specific clock to operate.
442 gst_element_set_clock (GstElement * element, GstClock * clock)
444 GstElementClass *oclass;
448 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
449 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
451 oclass = GST_ELEMENT_GET_CLASS (element);
453 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
455 if (oclass->set_clock)
456 res = oclass->set_clock (element, clock);
459 /* only update the clock pointer if the element accepted the clock */
460 GST_OBJECT_LOCK (element);
461 clock_p = &element->clock;
462 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
463 GST_OBJECT_UNLOCK (element);
469 * gst_element_get_clock:
470 * @element: a #GstElement to get the clock of.
472 * Gets the currently configured clock of the element. This is the clock as was
473 * last set with gst_element_set_clock().
475 * Returns: (transfer full): the #GstClock of the element. unref after usage.
480 gst_element_get_clock (GstElement * element)
484 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
486 GST_OBJECT_LOCK (element);
487 if ((result = element->clock))
488 gst_object_ref (result);
489 GST_OBJECT_UNLOCK (element);
495 * gst_element_set_base_time:
496 * @element: a #GstElement.
497 * @time: the base time to set.
499 * Set the base time of an element. See gst_element_get_base_time().
504 gst_element_set_base_time (GstElement * element, GstClockTime time)
508 g_return_if_fail (GST_IS_ELEMENT (element));
510 GST_OBJECT_LOCK (element);
511 old = element->base_time;
512 element->base_time = time;
513 GST_OBJECT_UNLOCK (element);
515 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
516 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
517 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
521 * gst_element_get_base_time:
522 * @element: a #GstElement.
524 * Returns the base time of the element. The base time is the
525 * absolute time of the clock when this element was last put to
526 * PLAYING. Subtracting the base time from the clock time gives
527 * the running time of the element.
529 * Returns: the base time of the element.
534 gst_element_get_base_time (GstElement * element)
538 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
540 GST_OBJECT_LOCK (element);
541 result = element->base_time;
542 GST_OBJECT_UNLOCK (element);
548 * gst_element_set_start_time:
549 * @element: a #GstElement.
550 * @time: the base time to set.
552 * Set the start time of an element. The start time of the element is the
553 * running time of the element when it last went to the PAUSED state. In READY
554 * or after a flushing seek, it is set to 0.
556 * Toplevel elements like #GstPipeline will manage the start_time and
557 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
558 * on such a toplevel element will disable the distribution of the base_time to
559 * the children and can be useful if the application manages the base_time
560 * itself, for example if you want to synchronize capture from multiple
561 * pipelines, and you can also ensure that the pipelines have the same clock.
568 gst_element_set_start_time (GstElement * element, GstClockTime time)
572 g_return_if_fail (GST_IS_ELEMENT (element));
574 GST_OBJECT_LOCK (element);
575 old = GST_ELEMENT_START_TIME (element);
576 GST_ELEMENT_START_TIME (element) = time;
577 GST_OBJECT_UNLOCK (element);
579 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
580 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
581 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
585 * gst_element_get_start_time:
586 * @element: a #GstElement.
588 * Returns the start time of the element. The start time is the
589 * running time of the clock when this element was last put to PAUSED.
591 * Usually the start_time is managed by a toplevel element such as
596 * Returns: the start time of the element.
601 gst_element_get_start_time (GstElement * element)
605 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
607 GST_OBJECT_LOCK (element);
608 result = GST_ELEMENT_START_TIME (element);
609 GST_OBJECT_UNLOCK (element);
615 * gst_element_is_indexable:
616 * @element: a #GstElement.
618 * Queries if the element can be indexed.
620 * Returns: TRUE if the element can be indexed.
625 gst_element_is_indexable (GstElement * element)
629 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
631 result = (GST_ELEMENT_GET_CLASS (element)->set_index != NULL);
637 * gst_element_set_index:
638 * @element: a #GstElement.
639 * @index: (transfer none): a #GstIndex.
641 * Set @index on the element. The refcount of the index
642 * will be increased, any previously set index is unreffed.
647 gst_element_set_index (GstElement * element, GstIndex * index)
649 GstElementClass *oclass;
651 g_return_if_fail (GST_IS_ELEMENT (element));
652 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
654 oclass = GST_ELEMENT_GET_CLASS (element);
656 if (oclass->set_index)
657 oclass->set_index (element, index);
661 * gst_element_get_index:
662 * @element: a #GstElement.
664 * Gets the index from the element.
666 * Returns: (transfer full): a #GstIndex or %NULL when no index was set on the
667 * element. unref after usage.
672 gst_element_get_index (GstElement * element)
674 GstElementClass *oclass;
675 GstIndex *result = NULL;
677 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
679 oclass = GST_ELEMENT_GET_CLASS (element);
681 if (oclass->get_index)
682 result = oclass->get_index (element);
688 * gst_element_add_pad:
689 * @element: a #GstElement to add the pad to.
690 * @pad: (transfer full): the #GstPad to add to the element.
692 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
693 * see gst_object_set_parent() for refcounting information.
695 * Pads are not automatically activated so elements should perform the needed
696 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
697 * state. See gst_pad_set_active() for more information about activating pads.
699 * The pad and the element should be unlocked when calling this function.
701 * This function will emit the #GstElement::pad-added signal on the element.
703 * Returns: %TRUE if the pad could be added. This function can fail when
704 * a pad with the same name already existed or the pad already had another
710 gst_element_add_pad (GstElement * element, GstPad * pad)
715 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
716 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
718 /* locking pad to look at the name */
719 GST_OBJECT_LOCK (pad);
720 pad_name = g_strdup (GST_PAD_NAME (pad));
721 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
722 GST_STR_NULL (pad_name));
723 flushing = GST_PAD_IS_FLUSHING (pad);
724 GST_OBJECT_UNLOCK (pad);
726 /* then check to see if there's already a pad by that name here */
727 GST_OBJECT_LOCK (element);
728 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
731 /* try to set the pad's parent */
732 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
733 GST_OBJECT_CAST (element))))
736 /* check for flushing pads */
737 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
738 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
739 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
740 "use gst_pad_set_active(pad,TRUE) before adding it.",
741 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
743 GST_OBJECT_LOCK (pad);
744 GST_PAD_UNSET_FLUSHING (pad);
745 GST_OBJECT_UNLOCK (pad);
750 /* add it to the list */
751 switch (gst_pad_get_direction (pad)) {
753 element->srcpads = g_list_prepend (element->srcpads, pad);
754 element->numsrcpads++;
757 element->sinkpads = g_list_prepend (element->sinkpads, pad);
758 element->numsinkpads++;
763 element->pads = g_list_prepend (element->pads, pad);
765 element->pads_cookie++;
766 GST_OBJECT_UNLOCK (element);
768 /* emit the PAD_ADDED signal */
769 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
776 g_critical ("Padname %s is not unique in element %s, not adding",
777 pad_name, GST_ELEMENT_NAME (element));
778 GST_OBJECT_UNLOCK (element);
785 ("Pad %s already has parent when trying to add to element %s",
786 pad_name, GST_ELEMENT_NAME (element));
787 GST_OBJECT_UNLOCK (element);
793 GST_OBJECT_LOCK (pad);
795 ("Trying to add pad %s to element %s, but it has no direction",
796 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
797 GST_OBJECT_UNLOCK (pad);
798 GST_OBJECT_UNLOCK (element);
804 * gst_element_remove_pad:
805 * @element: a #GstElement to remove pad from.
806 * @pad: (transfer none): the #GstPad to remove from the element.
808 * Removes @pad from @element. @pad will be destroyed if it has not been
809 * referenced elsewhere using gst_object_unparent().
811 * This function is used by plugin developers and should not be used
812 * by applications. Pads that were dynamically requested from elements
813 * with gst_element_get_request_pad() should be released with the
814 * gst_element_release_request_pad() function instead.
816 * Pads are not automatically deactivated so elements should perform the needed
817 * steps to deactivate the pad in case this pad is removed in the PAUSED or
818 * PLAYING state. See gst_pad_set_active() for more information about
821 * The pad and the element should be unlocked when calling this function.
823 * This function will emit the #GstElement::pad-removed signal on the element.
825 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
826 * pad does not belong to the provided element.
831 gst_element_remove_pad (GstElement * element, GstPad * pad)
835 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
836 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
838 /* locking pad to look at the name and parent */
839 GST_OBJECT_LOCK (pad);
840 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
841 GST_STR_NULL (GST_PAD_NAME (pad)));
843 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
845 GST_OBJECT_UNLOCK (pad);
848 if ((peer = gst_pad_get_peer (pad))) {
849 /* window for MT unsafeness, someone else could unlink here
850 * and then we call unlink with wrong pads. The unlink
851 * function would catch this and safely return failed. */
852 if (GST_PAD_IS_SRC (pad))
853 gst_pad_unlink (pad, peer);
855 gst_pad_unlink (peer, pad);
857 gst_object_unref (peer);
860 GST_OBJECT_LOCK (element);
861 /* remove it from the list */
862 switch (gst_pad_get_direction (pad)) {
864 element->srcpads = g_list_remove (element->srcpads, pad);
865 element->numsrcpads--;
868 element->sinkpads = g_list_remove (element->sinkpads, pad);
869 element->numsinkpads--;
872 g_critical ("Removing pad without direction???");
875 element->pads = g_list_remove (element->pads, pad);
877 element->pads_cookie++;
878 GST_OBJECT_UNLOCK (element);
880 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
881 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
883 gst_object_unparent (GST_OBJECT_CAST (pad));
890 /* FIXME, locking order? */
891 GST_OBJECT_LOCK (element);
892 g_critical ("Padname %s:%s does not belong to element %s when removing",
893 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
894 GST_OBJECT_UNLOCK (element);
895 GST_OBJECT_UNLOCK (pad);
901 * gst_element_no_more_pads:
902 * @element: a #GstElement
904 * Use this function to signal that the element does not expect any more pads
905 * to show up in the current pipeline. This function should be called whenever
906 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
907 * pad templates use this in combination with autopluggers to figure out that
908 * the element is done initializing its pads.
910 * This function emits the #GstElement::no-more-pads signal.
915 gst_element_no_more_pads (GstElement * element)
917 g_return_if_fail (GST_IS_ELEMENT (element));
919 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
923 pad_compare_name (GstPad * pad1, const gchar * name)
927 GST_OBJECT_LOCK (pad1);
928 result = strcmp (GST_PAD_NAME (pad1), name);
929 GST_OBJECT_UNLOCK (pad1);
935 * gst_element_get_static_pad:
936 * @element: a #GstElement to find a static pad of.
937 * @name: the name of the static #GstPad to retrieve.
939 * Retrieves a pad from @element by name. This version only retrieves
940 * already-existing (i.e. 'static') pads.
942 * Returns: (transfer full): the requested #GstPad if found, otherwise %NULL.
948 gst_element_get_static_pad (GstElement * element, const gchar * name)
951 GstPad *result = NULL;
953 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
954 g_return_val_if_fail (name != NULL, NULL);
956 GST_OBJECT_LOCK (element);
958 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
960 result = GST_PAD_CAST (find->data);
961 gst_object_ref (result);
964 if (result == NULL) {
965 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
966 name, GST_ELEMENT_NAME (element));
968 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
969 GST_ELEMENT_NAME (element), name);
971 GST_OBJECT_UNLOCK (element);
977 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
978 const gchar * name, const GstCaps * caps)
980 GstPad *newpad = NULL;
981 GstElementClass *oclass;
983 oclass = GST_ELEMENT_GET_CLASS (element);
985 #ifndef G_DISABLE_CHECKS
986 /* Some sanity checking here */
990 /* Is this the template name? */
991 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
992 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
994 const gchar *str, *data;
997 /* Otherwise check if it's a valid name for the name template */
998 str = strchr (templ->name_template, '%');
999 g_return_val_if_fail (str != NULL, NULL);
1000 g_return_val_if_fail (strncmp (templ->name_template, name,
1001 str - templ->name_template) == 0, NULL);
1002 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
1004 data = name + (str - templ->name_template);
1006 /* Can either be %s or %d or %u, do sanity checking for %d */
1007 if (*(str + 1) == 'd') {
1011 tmp = g_ascii_strtoll (data, &endptr, 10);
1012 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
1013 && *endptr == '\0', NULL);
1014 } else if (*(str + 1) == 'u') {
1018 tmp = g_ascii_strtoull (data, &endptr, 10);
1019 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
1023 pad = gst_element_get_static_pad (element, name);
1025 gst_object_unref (pad);
1026 /* FIXME 0.11: Change this to g_return_val_if_fail() */
1027 g_critical ("Element %s already has a pad named %s, the behaviour of "
1028 " gst_element_get_request_pad() for existing pads is undefined!",
1029 GST_ELEMENT_NAME (element), name);
1034 if (oclass->request_new_pad_full)
1035 newpad = (oclass->request_new_pad_full) (element, templ, name, caps);
1036 else if (oclass->request_new_pad)
1037 newpad = (oclass->request_new_pad) (element, templ, name);
1040 gst_object_ref (newpad);
1046 * gst_element_get_request_pad:
1047 * @element: a #GstElement to find a request pad of.
1048 * @name: the name of the request #GstPad to retrieve.
1050 * Retrieves a pad from the element by name. This version only retrieves
1051 * request pads. The pad should be released with
1052 * gst_element_release_request_pad().
1054 * This method is slow and will be deprecated in the future. New code should
1055 * use gst_element_request_pad() with the requested template.
1057 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1058 * Release after usage.
1061 gst_element_get_request_pad (GstElement * element, const gchar * name)
1063 GstPadTemplate *templ = NULL;
1065 const gchar *req_name = NULL;
1066 gboolean templ_found = FALSE;
1069 gchar *str, *endptr = NULL;
1070 GstElementClass *class;
1072 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1073 g_return_val_if_fail (name != NULL, NULL);
1075 class = GST_ELEMENT_GET_CLASS (element);
1077 /* if the name contains a %, we assume it's the complete template name. Get
1078 * the template and try to get a pad */
1079 if (strstr (name, "%")) {
1080 templ = gst_element_class_get_request_pad_template (class, name);
1085 /* there is no % in the name, try to find a matching template */
1086 list = class->padtemplates;
1087 while (!templ_found && list) {
1088 templ = (GstPadTemplate *) list->data;
1089 if (templ->presence == GST_PAD_REQUEST) {
1090 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1091 templ->name_template);
1092 /* see if we find an exact match */
1093 if (strcmp (name, templ->name_template) == 0) {
1098 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1099 and %d and %u, occurring at the end of the name_template, are the only
1101 else if ((str = strchr (templ->name_template, '%'))
1102 && strncmp (templ->name_template, name,
1103 str - templ->name_template) == 0
1104 && strlen (name) > str - templ->name_template) {
1105 data = name + (str - templ->name_template);
1106 if (*(str + 1) == 'd') {
1110 tmp = strtol (data, &endptr, 10);
1111 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1117 } else if (*(str + 1) == 'u') {
1121 tmp = strtoul (data, &endptr, 10);
1122 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1142 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1148 * gst_element_request_pad:
1149 * @element: a #GstElement to find a request pad of.
1150 * @templ: a #GstPadTemplate of which we want a pad of.
1151 * @name: (transfer none) (allow-none): the name of the request #GstPad
1152 * to retrieve. Can be %NULL.
1153 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1154 * request. Can be %NULL.
1156 * Retrieves a request pad from the element according to the provided template.
1158 * If the @caps are specified and the element implements thew new
1159 * request_new_pad_full virtual method, the element will use them to select
1160 * which pad to create.
1162 * The pad should be released with gst_element_release_request_pad().
1164 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1165 * Release after usage.
1170 gst_element_request_pad (GstElement * element,
1171 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1173 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1174 g_return_val_if_fail (templ != NULL, NULL);
1176 return _gst_element_request_pad (element, templ, name, caps);
1180 * gst_element_get_pad:
1181 * @element: a #GstElement.
1182 * @name: the name of the pad to retrieve.
1184 * Retrieves a pad from @element by name. Tries gst_element_get_static_pad()
1185 * first, then gst_element_get_request_pad().
1187 * Deprecated: This function is deprecated as it's unclear if the reference
1188 * to the result pad should be released with gst_object_unref() in case of a static pad
1189 * or gst_element_release_request_pad() in case of a request pad.
1190 * Use gst_element_get_static_pad() or gst_element_get_request_pad() instead.
1192 * Returns: (transfer full): the #GstPad if found, otherwise %NULL. Unref or Release after usage,
1193 * depending on the type of the pad.
1195 #ifndef GST_REMOVE_DEPRECATED
1196 #ifdef GST_DISABLE_DEPRECATED
1197 GstPad *gst_element_get_pad (GstElement * element, const gchar * name);
1200 gst_element_get_pad (GstElement * element, const gchar * name)
1204 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1205 g_return_val_if_fail (name != NULL, NULL);
1207 pad = gst_element_get_static_pad (element, name);
1209 pad = gst_element_get_request_pad (element, name);
1213 #endif /* GST_REMOVE_DEPRECATED */
1215 static GstIteratorItem
1216 iterate_pad (GstIterator * it, GstPad * pad)
1218 gst_object_ref (pad);
1219 return GST_ITERATOR_ITEM_PASS;
1222 static GstIterator *
1223 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1225 GstIterator *result;
1227 GST_OBJECT_LOCK (element);
1228 gst_object_ref (element);
1229 result = gst_iterator_new_list (GST_TYPE_PAD,
1230 GST_OBJECT_GET_LOCK (element),
1231 &element->pads_cookie,
1234 (GstIteratorItemFunction) iterate_pad,
1235 (GstIteratorDisposeFunction) gst_object_unref);
1236 GST_OBJECT_UNLOCK (element);
1242 * gst_element_iterate_pads:
1243 * @element: a #GstElement to iterate pads of.
1245 * Retrieves an iterattor of @element's pads. The iterator should
1246 * be freed after usage.
1248 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1254 gst_element_iterate_pads (GstElement * element)
1256 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1258 return gst_element_iterate_pad_list (element, &element->pads);
1262 * gst_element_iterate_src_pads:
1263 * @element: a #GstElement.
1265 * Retrieves an iterator of @element's source pads.
1267 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1273 gst_element_iterate_src_pads (GstElement * element)
1275 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1277 return gst_element_iterate_pad_list (element, &element->srcpads);
1281 * gst_element_iterate_sink_pads:
1282 * @element: a #GstElement.
1284 * Retrieves an iterator of @element's sink pads.
1286 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1292 gst_element_iterate_sink_pads (GstElement * element)
1294 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1296 return gst_element_iterate_pad_list (element, &element->sinkpads);
1300 * gst_element_class_add_pad_template:
1301 * @klass: the #GstElementClass to add the pad template to.
1302 * @templ: (transfer none): a #GstPadTemplate to add to the element class.
1304 * Adds a padtemplate to an element class. This is mainly used in the _base_init
1305 * functions of classes.
1308 gst_element_class_add_pad_template (GstElementClass * klass,
1309 GstPadTemplate * templ)
1311 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1312 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1314 /* FIXME 0.11: allow replacing the pad templates by
1315 * calling this with the same name as an already existing pad
1316 * template. For this we _must_ _not_ ref the added pad template
1317 * a second time and _must_ document that this function takes
1318 * ownership of the pad template. Otherwise we will leak pad templates
1319 * or the caller unref's the pad template and it disappears */
1320 /* avoid registering pad templates with the same name */
1321 g_return_if_fail (gst_element_class_get_pad_template (klass,
1322 templ->name_template) == NULL);
1324 klass->padtemplates = g_list_append (klass->padtemplates,
1325 gst_object_ref (templ));
1326 klass->numpadtemplates++;
1330 gst_element_class_add_meta_data (GstElementClass * klass,
1331 const gchar * key, const gchar * value)
1333 if (!klass->meta_data) {
1334 /* FIXME: use a quark for "metadata" */
1335 klass->meta_data = gst_structure_empty_new ("metadata");
1338 gst_structure_set ((GstStructure *) klass->meta_data,
1339 key, G_TYPE_STRING, value, NULL);
1343 * gst_element_class_set_documentation_uri:
1344 * @klass: class to set details for
1345 * @uri: uri of element documentation
1347 * Set uri pointing to user documentation. Applications can use this to show
1348 * help for e.g. effects to users.
1353 gst_element_class_set_documentation_uri (GstElementClass * klass,
1356 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1358 gst_element_class_add_meta_data (klass, "doc-uri", uri);
1362 * gst_element_class_set_icon_name:
1363 * @klass: class to set details for
1364 * @name: name of an icon
1366 * Elements that bridge to certain other products can include an icon of that
1367 * used product. Application can show the icon in menus/selectors to help
1368 * identifying specific elements.
1373 gst_element_class_set_icon_name (GstElementClass * klass, const gchar * name)
1375 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1377 gst_element_class_add_meta_data (klass, "icon-name", name);
1380 /* FIXME-0.11: deprecate and remove gst_element_class_set_details*() */
1382 * gst_element_class_set_details:
1383 * @klass: class to set details for
1384 * @details: details to set
1386 * Sets the detailed information for a #GstElementClass.
1387 * <note>This function is for use in _base_init functions only.</note>
1389 * The @details are copied.
1391 * Deprecated: Use gst_element_class_set_details_simple() instead.
1393 #ifndef GST_REMOVE_DEPRECATED
1394 #ifdef GST_DISABLE_DEPRECATED
1395 void gst_element_class_set_details (GstElementClass * klass,
1396 const GstElementDetails * details);
1399 gst_element_class_set_details (GstElementClass * klass,
1400 const GstElementDetails * details)
1402 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1403 g_return_if_fail (GST_IS_ELEMENT_DETAILS (details));
1405 __gst_element_details_copy (&klass->details, details);
1410 * gst_element_class_set_details_simple:
1411 * @klass: class to set details for
1412 * @longname: The long English name of the element. E.g. "File Sink"
1413 * @classification: String describing the type of element, as an unordered list
1414 * separated with slashes ('/'). See draft-klass.txt of the design docs
1415 * for more details and common types. E.g: "Sink/File"
1416 * @description: Sentence describing the purpose of the element.
1417 * E.g: "Write stream to a file"
1418 * @author: Name and contact details of the author(s). Use \n to separate
1419 * multiple author details. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1421 * Sets the detailed information for a #GstElementClass. Simpler version of
1422 * gst_element_class_set_details() that generates less linker overhead.
1423 * <note>This function is for use in _base_init functions only.</note>
1425 * The detail parameter strings are copied into the #GstElementDetails for
1426 * the element class.
1431 gst_element_class_set_details_simple (GstElementClass * klass,
1432 const gchar * longname, const gchar * classification,
1433 const gchar * description, const gchar * author)
1435 const GstElementDetails details =
1436 GST_ELEMENT_DETAILS ((gchar *) longname, (gchar *) classification,
1437 (gchar *) description, (gchar *) author);
1439 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1441 __gst_element_details_copy (&klass->details, &details);
1445 * gst_element_class_get_pad_template_list:
1446 * @element_class: a #GstElementClass to get pad templates of.
1448 * Retrieves a list of the pad templates associated with @element_class. The
1449 * list must not be modified by the calling code.
1450 * <note>If you use this function in the #GInstanceInitFunc of an object class
1451 * that has subclasses, make sure to pass the g_class parameter of the
1452 * #GInstanceInitFunc here.</note>
1454 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1458 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1460 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1462 return element_class->padtemplates;
1466 * gst_element_class_get_pad_template:
1467 * @element_class: a #GstElementClass to get the pad template of.
1468 * @name: the name of the #GstPadTemplate to get.
1470 * Retrieves a padtemplate from @element_class with the given name.
1471 * <note>If you use this function in the #GInstanceInitFunc of an object class
1472 * that has subclasses, make sure to pass the g_class parameter of the
1473 * #GInstanceInitFunc here.</note>
1475 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1476 * if none was found. No unreferencing is necessary.
1479 gst_element_class_get_pad_template (GstElementClass *
1480 element_class, const gchar * name)
1484 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1485 g_return_val_if_fail (name != NULL, NULL);
1487 padlist = element_class->padtemplates;
1490 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1492 if (strcmp (padtempl->name_template, name) == 0)
1495 padlist = g_list_next (padlist);
1501 static GstPadTemplate *
1502 gst_element_class_get_request_pad_template (GstElementClass *
1503 element_class, const gchar * name)
1505 GstPadTemplate *tmpl;
1507 tmpl = gst_element_class_get_pad_template (element_class, name);
1508 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1514 /* get a random pad on element of the given direction.
1515 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1518 gst_element_get_random_pad (GstElement * element,
1519 gboolean need_linked, GstPadDirection dir)
1521 GstPad *result = NULL;
1524 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1528 GST_OBJECT_LOCK (element);
1529 pads = element->srcpads;
1532 GST_OBJECT_LOCK (element);
1533 pads = element->sinkpads;
1536 goto wrong_direction;
1538 for (; pads; pads = g_list_next (pads)) {
1539 GstPad *pad = GST_PAD_CAST (pads->data);
1541 GST_OBJECT_LOCK (pad);
1542 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1543 GST_DEBUG_PAD_NAME (pad));
1545 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1546 /* if we require a linked pad, and it is not linked, continue the
1548 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1549 GST_DEBUG_PAD_NAME (pad));
1550 GST_OBJECT_UNLOCK (pad);
1553 /* found a pad, stop search */
1554 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1555 GST_DEBUG_PAD_NAME (pad));
1556 GST_OBJECT_UNLOCK (pad);
1562 gst_object_ref (result);
1564 GST_OBJECT_UNLOCK (element);
1568 /* ERROR handling */
1571 g_warning ("unknown pad direction %d", dir);
1577 gst_element_default_send_event (GstElement * element, GstEvent * event)
1579 gboolean result = FALSE;
1582 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1583 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1584 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1587 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1588 "pushing %s event to random %s pad %s:%s",
1589 GST_EVENT_TYPE_NAME (event),
1590 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1591 GST_DEBUG_PAD_NAME (pad));
1593 result = gst_pad_push_event (pad, event);
1594 gst_object_unref (pad);
1596 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1597 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1598 gst_event_unref (event);
1604 * gst_element_send_event:
1605 * @element: a #GstElement to send the event to.
1606 * @event: (transfer full): the #GstEvent to send to the element.
1608 * Sends an event to an element. If the element doesn't implement an
1609 * event handler, the event will be pushed on a random linked sink pad for
1610 * upstream events or a random linked source pad for downstream events.
1612 * This function takes owership of the provided event so you should
1613 * gst_event_ref() it if you want to reuse the event after this call.
1615 * Returns: %TRUE if the event was handled.
1620 gst_element_send_event (GstElement * element, GstEvent * event)
1622 GstElementClass *oclass;
1623 gboolean result = FALSE;
1625 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1626 g_return_val_if_fail (event != NULL, FALSE);
1628 oclass = GST_ELEMENT_GET_CLASS (element);
1630 GST_STATE_LOCK (element);
1631 if (oclass->send_event) {
1632 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1633 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1634 result = oclass->send_event (element, event);
1636 result = gst_element_default_send_event (element, event);
1638 GST_STATE_UNLOCK (element);
1645 * @element: a #GstElement to send the event to.
1646 * @rate: The new playback rate
1647 * @format: The format of the seek values
1648 * @flags: The optional seek flags.
1649 * @cur_type: The type and flags for the new current position
1650 * @cur: The value of the new current position
1651 * @stop_type: The type and flags for the new stop position
1652 * @stop: The value of the new stop position
1654 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1655 * the parameters. The seek event is sent to the element using
1656 * gst_element_send_event().
1658 * Returns: %TRUE if the event was handled.
1663 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1664 GstSeekFlags flags, GstSeekType cur_type, gint64 cur,
1665 GstSeekType stop_type, gint64 stop)
1670 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1673 gst_event_new_seek (rate, format, flags, cur_type, cur, stop_type, stop);
1674 result = gst_element_send_event (element, event);
1680 * gst_element_get_query_types:
1681 * @element: a #GstElement to query
1683 * Get an array of query types from the element.
1684 * If the element doesn't implement a query types function,
1685 * the query will be forwarded to the peer of a random linked sink pad.
1687 * Returns: An array of #GstQueryType elements that should not
1688 * be freed or modified.
1692 const GstQueryType *
1693 gst_element_get_query_types (GstElement * element)
1695 GstElementClass *oclass;
1696 const GstQueryType *result = NULL;
1698 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1700 oclass = GST_ELEMENT_GET_CLASS (element);
1702 if (oclass->get_query_types) {
1703 result = oclass->get_query_types (element);
1705 GstPad *pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1708 GstPad *peer = gst_pad_get_peer (pad);
1711 result = gst_pad_get_query_types (peer);
1713 gst_object_unref (peer);
1715 gst_object_unref (pad);
1722 gst_element_default_query (GstElement * element, GstQuery * query)
1724 gboolean result = FALSE;
1727 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1729 result = gst_pad_query (pad, query);
1731 gst_object_unref (pad);
1733 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1735 GstPad *peer = gst_pad_get_peer (pad);
1738 result = gst_pad_query (peer, query);
1740 gst_object_unref (peer);
1742 gst_object_unref (pad);
1749 * gst_element_query:
1750 * @element: a #GstElement to perform the query on.
1751 * @query: (transfer none): the #GstQuery.
1753 * Performs a query on the given element.
1755 * For elements that don't implement a query handler, this function
1756 * forwards the query to a random srcpad or to the peer of a
1757 * random linked sinkpad of this element.
1759 * Please note that some queries might need a running pipeline to work.
1761 * Returns: TRUE if the query could be performed.
1766 gst_element_query (GstElement * element, GstQuery * query)
1768 GstElementClass *oclass;
1769 gboolean result = FALSE;
1771 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1772 g_return_val_if_fail (query != NULL, FALSE);
1774 oclass = GST_ELEMENT_GET_CLASS (element);
1776 if (oclass->query) {
1777 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1778 GST_ELEMENT_NAME (element));
1779 result = oclass->query (element, query);
1781 result = gst_element_default_query (element, query);
1787 * gst_element_post_message:
1788 * @element: a #GstElement posting the message
1789 * @message: (transfer full): a #GstMessage to post
1791 * Post a message on the element's #GstBus. This function takes ownership of the
1792 * message; if you want to access the message after this call, you should add an
1793 * additional reference before calling.
1795 * Returns: %TRUE if the message was successfully posted. The function returns
1796 * %FALSE if the element did not have a bus.
1801 gst_element_post_message (GstElement * element, GstMessage * message)
1804 gboolean result = FALSE;
1806 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1807 g_return_val_if_fail (message != NULL, FALSE);
1809 GST_OBJECT_LOCK (element);
1812 if (G_UNLIKELY (bus == NULL))
1815 gst_object_ref (bus);
1816 GST_OBJECT_UNLOCK (element);
1818 /* we release the element lock when posting the message so that any
1819 * (synchronous) message handlers can operate on the element */
1820 result = gst_bus_post (bus, message);
1821 gst_object_unref (bus);
1828 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1829 "not posting message %p: no bus", message);
1830 GST_OBJECT_UNLOCK (element);
1831 gst_message_unref (message);
1837 * _gst_element_error_printf:
1838 * @format: the printf-like format to use, or %NULL
1840 * This function is only used internally by the gst_element_error() macro.
1842 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1848 _gst_element_error_printf (const gchar * format, ...)
1858 va_start (args, format);
1859 buffer = g_strdup_vprintf (format, args);
1865 * gst_element_message_full:
1866 * @element: a #GstElement to send message from
1867 * @type: the #GstMessageType
1868 * @domain: the GStreamer GError domain this message belongs to
1869 * @code: the GError code belonging to the domain
1870 * @text: (allow-none) (transfer full): an allocated text string to be used
1871 * as a replacement for the default message connected to code,
1873 * @debug: (allow-none) (transfer full): an allocated debug message to be
1874 * used as a replacement for the default debugging information,
1876 * @file: the source code file where the error was generated
1877 * @function: the source code function where the error was generated
1878 * @line: the source code line where the error was generated
1880 * Post an error, warning or info message on the bus from inside an element.
1882 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1883 * #GST_MESSAGE_INFO.
1887 void gst_element_message_full
1888 (GstElement * element, GstMessageType type,
1889 GQuark domain, gint code, gchar * text,
1890 gchar * debug, const gchar * file, const gchar * function, gint line)
1892 GError *gerror = NULL;
1896 gboolean has_debug = TRUE;
1897 GstMessage *message = NULL;
1900 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1901 g_return_if_fail (GST_IS_ELEMENT (element));
1902 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1903 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1905 /* check if we send the given text or the default error text */
1906 if ((text == NULL) || (text[0] == 0)) {
1907 /* text could have come from g_strdup_printf (""); */
1909 sent_text = gst_error_get_message (domain, code);
1913 /* construct a sent_debug with extra information from source */
1914 if ((debug == NULL) || (debug[0] == 0)) {
1915 /* debug could have come from g_strdup_printf (""); */
1919 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1921 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1922 file, line, function, name, debug);
1924 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1925 file, line, function, name);
1929 /* create gerror and post message */
1930 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1932 gerror = g_error_new_literal (domain, code, sent_text);
1935 case GST_MESSAGE_ERROR:
1937 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1939 case GST_MESSAGE_WARNING:
1940 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1943 case GST_MESSAGE_INFO:
1944 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1948 g_assert_not_reached ();
1951 gst_element_post_message (element, message);
1953 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1954 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1957 g_error_free (gerror);
1958 g_free (sent_debug);
1963 * gst_element_is_locked_state:
1964 * @element: a #GstElement.
1966 * Checks if the state of an element is locked.
1967 * If the state of an element is locked, state changes of the parent don't
1968 * affect the element.
1969 * This way you can leave currently unused elements inside bins. Just lock their
1970 * state before changing the state from #GST_STATE_NULL.
1974 * Returns: TRUE, if the element's state is locked.
1977 gst_element_is_locked_state (GstElement * element)
1981 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1983 GST_OBJECT_LOCK (element);
1984 result = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1985 GST_OBJECT_UNLOCK (element);
1991 * gst_element_set_locked_state:
1992 * @element: a #GstElement
1993 * @locked_state: TRUE to lock the element's state
1995 * Locks the state of an element, so state changes of the parent don't affect
1996 * this element anymore.
2000 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
2001 * or the elements state-locking needed no change.
2004 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
2008 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
2010 GST_OBJECT_LOCK (element);
2011 old = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
2013 if (G_UNLIKELY (old == locked_state))
2017 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
2018 GST_ELEMENT_NAME (element));
2019 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_LOCKED_STATE);
2021 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
2022 GST_ELEMENT_NAME (element));
2023 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_LOCKED_STATE);
2025 GST_OBJECT_UNLOCK (element);
2031 GST_CAT_DEBUG (GST_CAT_STATES,
2032 "elements %s was already in locked state %d",
2033 GST_ELEMENT_NAME (element), old);
2034 GST_OBJECT_UNLOCK (element);
2041 * gst_element_sync_state_with_parent:
2042 * @element: a #GstElement.
2044 * Tries to change the state of the element to the same as its parent.
2045 * If this function returns FALSE, the state of element is undefined.
2047 * Returns: TRUE, if the element's state could be synced to the parent's state.
2052 gst_element_sync_state_with_parent (GstElement * element)
2056 GstStateChangeReturn ret;
2058 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
2060 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
2061 GstState parent_current, parent_pending;
2063 GST_OBJECT_LOCK (parent);
2064 parent_current = GST_STATE (parent);
2065 parent_pending = GST_STATE_PENDING (parent);
2066 GST_OBJECT_UNLOCK (parent);
2068 /* set to pending if there is one, else we set it to the current state of
2070 if (parent_pending != GST_STATE_VOID_PENDING)
2071 target = parent_pending;
2073 target = parent_current;
2075 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2076 "syncing state (%s) to parent %s %s (%s, %s)",
2077 gst_element_state_get_name (GST_STATE (element)),
2078 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
2079 gst_element_state_get_name (parent_current),
2080 gst_element_state_get_name (parent_pending));
2082 ret = gst_element_set_state (element, target);
2083 if (ret == GST_STATE_CHANGE_FAILURE)
2086 gst_object_unref (parent);
2090 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
2097 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2098 "syncing state failed (%s)",
2099 gst_element_state_change_return_get_name (ret));
2100 gst_object_unref (parent);
2106 static GstStateChangeReturn
2107 gst_element_get_state_func (GstElement * element,
2108 GstState * state, GstState * pending, GstClockTime timeout)
2110 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2111 GstState old_pending;
2113 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2114 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2116 GST_OBJECT_LOCK (element);
2117 ret = GST_STATE_RETURN (element);
2118 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2119 gst_element_state_change_return_get_name (ret));
2121 /* we got an error, report immediately */
2122 if (ret == GST_STATE_CHANGE_FAILURE)
2125 /* we got no_preroll, report immediatly */
2126 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2129 /* no need to wait async if we are not async */
2130 if (ret != GST_STATE_CHANGE_ASYNC)
2133 old_pending = GST_STATE_PENDING (element);
2134 if (old_pending != GST_STATE_VOID_PENDING) {
2135 GTimeVal *timeval, abstimeout;
2138 if (timeout != GST_CLOCK_TIME_NONE) {
2139 glong add = timeout / 1000;
2144 /* make timeout absolute */
2145 g_get_current_time (&abstimeout);
2146 g_time_val_add (&abstimeout, add);
2147 timeval = &abstimeout;
2151 /* get cookie to detect state changes during waiting */
2152 cookie = element->state_cookie;
2154 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2155 "waiting for element to commit state");
2157 /* we have a pending state change, wait for it to complete */
2158 if (!GST_STATE_TIMED_WAIT (element, timeval)) {
2159 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2160 /* timeout triggered */
2161 ret = GST_STATE_CHANGE_ASYNC;
2163 if (cookie != element->state_cookie)
2166 /* could be success or failure */
2167 if (old_pending == GST_STATE (element)) {
2168 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2169 ret = GST_STATE_CHANGE_SUCCESS;
2171 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2172 ret = GST_STATE_CHANGE_FAILURE;
2175 /* if nothing is pending anymore we can return SUCCESS */
2176 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2177 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2178 ret = GST_STATE_CHANGE_SUCCESS;
2184 *state = GST_STATE (element);
2186 *pending = GST_STATE_PENDING (element);
2188 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2189 "state current: %s, pending: %s, result: %s",
2190 gst_element_state_get_name (GST_STATE (element)),
2191 gst_element_state_get_name (GST_STATE_PENDING (element)),
2192 gst_element_state_change_return_get_name (ret));
2193 GST_OBJECT_UNLOCK (element);
2200 *state = GST_STATE_VOID_PENDING;
2202 *pending = GST_STATE_VOID_PENDING;
2204 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2206 GST_OBJECT_UNLOCK (element);
2208 return GST_STATE_CHANGE_FAILURE;
2213 * gst_element_get_state:
2214 * @element: a #GstElement to get the state of.
2215 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2217 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2218 * state. Can be %NULL.
2219 * @timeout: a #GstClockTime to specify the timeout for an async
2220 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2222 * Gets the state of the element.
2224 * For elements that performed an ASYNC state change, as reported by
2225 * gst_element_set_state(), this function will block up to the
2226 * specified timeout value for the state change to complete.
2227 * If the element completes the state change or goes into
2228 * an error, this function returns immediately with a return value of
2229 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2231 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2232 * returns the current and pending state immediately.
2234 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2235 * successfully changed its state but is not able to provide data yet.
2236 * This mostly happens for live sources that only produce data in
2237 * %GST_STATE_PLAYING. While the state change return is equivalent to
2238 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2239 * some sink elements might not be able to complete their state change because
2240 * an element is not producing data to complete the preroll. When setting the
2241 * element to playing, the preroll will complete and playback will start.
2243 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2244 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2245 * element is still performing a state change or
2246 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2250 GstStateChangeReturn
2251 gst_element_get_state (GstElement * element,
2252 GstState * state, GstState * pending, GstClockTime timeout)
2254 GstElementClass *oclass;
2255 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2257 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2259 oclass = GST_ELEMENT_GET_CLASS (element);
2261 if (oclass->get_state)
2262 result = (oclass->get_state) (element, state, pending, timeout);
2268 * gst_element_abort_state:
2269 * @element: a #GstElement to abort the state of.
2271 * Abort the state change of the element. This function is used
2272 * by elements that do asynchronous state changes and find out
2273 * something is wrong.
2275 * This function should be called with the STATE_LOCK held.
2280 gst_element_abort_state (GstElement * element)
2284 #ifndef GST_DISABLE_GST_DEBUG
2288 g_return_if_fail (GST_IS_ELEMENT (element));
2290 GST_OBJECT_LOCK (element);
2291 pending = GST_STATE_PENDING (element);
2293 if (pending == GST_STATE_VOID_PENDING ||
2294 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2295 goto nothing_aborted;
2297 #ifndef GST_DISABLE_GST_DEBUG
2298 old_state = GST_STATE (element);
2300 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2301 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2302 gst_element_state_get_name (pending));
2306 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2308 GST_STATE_BROADCAST (element);
2309 GST_OBJECT_UNLOCK (element);
2315 GST_OBJECT_UNLOCK (element);
2321 * gst_element_continue_state:
2322 * @element: a #GstElement to continue the state change of.
2323 * @ret: The previous state return value
2325 * Commit the state change of the element and proceed to the next
2326 * pending state if any. This function is used
2327 * by elements that do asynchronous state changes.
2328 * The core will normally call this method automatically when an
2329 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2331 * If after calling this method the element still has not reached
2332 * the pending state, the next state change is performed.
2334 * This method is used internally and should normally not be called by plugins
2337 * Returns: The result of the commit state change.
2341 GstStateChangeReturn
2342 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2344 GstStateChangeReturn old_ret;
2345 GstState old_state, old_next;
2346 GstState current, next, pending;
2347 GstMessage *message;
2348 GstStateChange transition;
2350 GST_OBJECT_LOCK (element);
2351 old_ret = GST_STATE_RETURN (element);
2352 GST_STATE_RETURN (element) = ret;
2353 pending = GST_STATE_PENDING (element);
2355 /* check if there is something to commit */
2356 if (pending == GST_STATE_VOID_PENDING)
2357 goto nothing_pending;
2359 old_state = GST_STATE (element);
2360 /* this is the state we should go to next */
2361 old_next = GST_STATE_NEXT (element);
2362 /* update current state */
2363 current = GST_STATE (element) = old_next;
2365 /* see if we reached the final state */
2366 if (pending == current)
2369 next = GST_STATE_GET_NEXT (current, pending);
2370 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2372 GST_STATE_NEXT (element) = next;
2374 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2375 GST_OBJECT_UNLOCK (element);
2377 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2378 "committing state from %s to %s, pending %s, next %s",
2379 gst_element_state_get_name (old_state),
2380 gst_element_state_get_name (old_next),
2381 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2383 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2384 old_state, old_next, pending);
2385 gst_element_post_message (element, message);
2387 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2388 "continue state change %s to %s, final %s",
2389 gst_element_state_get_name (current),
2390 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2392 ret = gst_element_change_state (element, transition);
2398 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2399 GST_OBJECT_UNLOCK (element);
2404 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2405 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2407 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2408 "completed state change to %s", gst_element_state_get_name (pending));
2409 GST_OBJECT_UNLOCK (element);
2411 /* don't post silly messages with the same state. This can happen
2412 * when an element state is changed to what it already was. For bins
2413 * this can be the result of a lost state, which we check with the
2414 * previous return value.
2415 * We do signal the cond though as a _get_state() might be blocking
2417 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC) {
2418 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2419 "posting state-changed %s to %s",
2420 gst_element_state_get_name (old_state),
2421 gst_element_state_get_name (old_next));
2423 gst_message_new_state_changed (GST_OBJECT_CAST (element), old_state,
2424 old_next, GST_STATE_VOID_PENDING);
2425 gst_element_post_message (element, message);
2428 GST_STATE_BROADCAST (element);
2435 * gst_element_lost_state_full:
2436 * @element: a #GstElement the state is lost of
2437 * @new_base_time: if a new base time should be distributed
2439 * Brings the element to the lost state. The current state of the
2440 * element is copied to the pending state so that any call to
2441 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2443 * An ASYNC_START message is posted with indication to distribute a new
2444 * base_time to the element when @new_base_time is %TRUE.
2445 * If the element was PLAYING, it will go to PAUSED. The element
2446 * will be restored to its PLAYING state by the parent pipeline when it
2449 * This is mostly used for elements that lost their preroll buffer
2450 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2451 * they will go to their pending state again when a new preroll buffer is
2452 * queued. This function can only be called when the element is currently
2453 * not in error or an async state change.
2455 * This function is used internally and should normally not be called from
2456 * plugins or applications.
2463 gst_element_lost_state_full (GstElement * element, gboolean new_base_time)
2465 GstState old_state, new_state;
2466 GstMessage *message;
2468 g_return_if_fail (GST_IS_ELEMENT (element));
2470 GST_OBJECT_LOCK (element);
2471 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2474 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2475 goto only_async_start;
2477 old_state = GST_STATE (element);
2479 /* when we were PLAYING, the new state is PAUSED. We will also not
2480 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2481 * when we preroll. */
2482 if (old_state > GST_STATE_PAUSED)
2483 new_state = GST_STATE_PAUSED;
2485 new_state = old_state;
2487 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2488 "lost state of %s to %s", gst_element_state_get_name (old_state),
2489 gst_element_state_get_name (new_state));
2491 GST_STATE (element) = new_state;
2492 GST_STATE_NEXT (element) = new_state;
2493 GST_STATE_PENDING (element) = new_state;
2494 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2496 GST_ELEMENT_START_TIME (element) = 0;
2497 GST_OBJECT_UNLOCK (element);
2499 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2500 new_state, new_state, new_state);
2501 gst_element_post_message (element, message);
2504 gst_message_new_async_start (GST_OBJECT_CAST (element), new_base_time);
2505 gst_element_post_message (element, message);
2511 GST_OBJECT_UNLOCK (element);
2516 GST_OBJECT_UNLOCK (element);
2518 message = gst_message_new_async_start (GST_OBJECT_CAST (element), TRUE);
2519 gst_element_post_message (element, message);
2525 * gst_element_lost_state:
2526 * @element: a #GstElement the state is lost of
2528 * Brings the element to the lost state. This function calls
2529 * gst_element_lost_state_full() with the new_base_time set to %TRUE.
2531 * This function is used internally and should normally not be called from
2532 * plugins or applications.
2537 gst_element_lost_state (GstElement * element)
2539 gst_element_lost_state_full (element, TRUE);
2543 * gst_element_set_state:
2544 * @element: a #GstElement to change state of.
2545 * @state: the element's new #GstState.
2547 * Sets the state of the element. This function will try to set the
2548 * requested state by going through all the intermediary states and calling
2549 * the class's state change function for each.
2551 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2552 * element will perform the remainder of the state change asynchronously in
2554 * An application can use gst_element_get_state() to wait for the completion
2555 * of the state change or it can wait for a state change message on the bus.
2557 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2558 * #GST_STATE_CHANGE_ASYNC.
2560 * Returns: Result of the state change using #GstStateChangeReturn.
2564 GstStateChangeReturn
2565 gst_element_set_state (GstElement * element, GstState state)
2567 GstElementClass *oclass;
2568 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2570 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2572 oclass = GST_ELEMENT_GET_CLASS (element);
2574 if (oclass->set_state)
2575 result = (oclass->set_state) (element, state);
2581 * default set state function, calculates the next state based
2582 * on current state and calls the change_state function
2584 static GstStateChangeReturn
2585 gst_element_set_state_func (GstElement * element, GstState state)
2587 GstState current, next, old_pending;
2588 GstStateChangeReturn ret;
2589 GstStateChange transition;
2590 GstStateChangeReturn old_ret;
2592 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2594 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2595 gst_element_state_get_name (state));
2597 /* state lock is taken to protect the set_state() and get_state()
2598 * procedures, it does not lock any variables. */
2599 GST_STATE_LOCK (element);
2601 /* now calculate how to get to the new state */
2602 GST_OBJECT_LOCK (element);
2603 old_ret = GST_STATE_RETURN (element);
2604 /* previous state change returned an error, remove all pending
2605 * and next states */
2606 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2607 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2608 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2609 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2612 current = GST_STATE (element);
2613 next = GST_STATE_NEXT (element);
2614 old_pending = GST_STATE_PENDING (element);
2616 /* this is the (new) state we should go to. TARGET is the last state we set on
2618 if (state != GST_STATE_TARGET (element)) {
2619 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2620 "setting target state to %s", gst_element_state_get_name (state));
2621 GST_STATE_TARGET (element) = state;
2622 /* increment state cookie so that we can track each state change. We only do
2623 * this if this is actually a new state change. */
2624 element->state_cookie++;
2626 GST_STATE_PENDING (element) = state;
2628 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2629 "current %s, old_pending %s, next %s, old return %s",
2630 gst_element_state_get_name (current),
2631 gst_element_state_get_name (old_pending),
2632 gst_element_state_get_name (next),
2633 gst_element_state_change_return_get_name (old_ret));
2635 /* if the element was busy doing a state change, we just update the
2636 * target state, it'll get to it async then. */
2637 if (old_pending != GST_STATE_VOID_PENDING) {
2638 /* upwards state change will happen ASYNC */
2639 if (old_pending <= state)
2641 /* element is going to this state already */
2642 else if (next == state)
2644 /* element was performing an ASYNC upward state change and
2645 * we request to go downward again. Start from the next pending
2647 else if (next > state
2648 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2652 next = GST_STATE_GET_NEXT (current, state);
2653 /* now we store the next state */
2654 GST_STATE_NEXT (element) = next;
2655 /* mark busy, we need to check that there is actually a state change
2656 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2657 * the default element change_state function has no way to know what the
2658 * old value was... could consider this a FIXME...*/
2659 if (current != next)
2660 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2662 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2664 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2665 "%s: setting state from %s to %s",
2666 (next != state ? "intermediate" : "final"),
2667 gst_element_state_get_name (current), gst_element_state_get_name (next));
2669 /* now signal any waiters, they will error since the cookie was incremented */
2670 GST_STATE_BROADCAST (element);
2672 GST_OBJECT_UNLOCK (element);
2674 ret = gst_element_change_state (element, transition);
2676 GST_STATE_UNLOCK (element);
2678 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2679 gst_element_state_change_return_get_name (ret));
2685 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2686 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2687 "element was busy with async state change");
2688 GST_OBJECT_UNLOCK (element);
2690 GST_STATE_UNLOCK (element);
2692 return GST_STATE_CHANGE_ASYNC;
2697 * gst_element_change_state:
2698 * @element: a #GstElement
2699 * @transition: the requested transition
2701 * Perform @transition on @element.
2703 * This function must be called with STATE_LOCK held and is mainly used
2706 * Returns: the #GstStateChangeReturn of the state transition.
2708 GstStateChangeReturn
2709 gst_element_change_state (GstElement * element, GstStateChange transition)
2711 GstElementClass *oclass;
2712 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2714 oclass = GST_ELEMENT_GET_CLASS (element);
2716 /* call the state change function so it can set the state */
2717 if (oclass->change_state)
2718 ret = (oclass->change_state) (element, transition);
2720 ret = GST_STATE_CHANGE_FAILURE;
2723 case GST_STATE_CHANGE_FAILURE:
2724 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2725 "have FAILURE change_state return");
2726 /* state change failure */
2727 gst_element_abort_state (element);
2729 case GST_STATE_CHANGE_ASYNC:
2733 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2734 "element will change state ASYNC");
2736 target = GST_STATE_TARGET (element);
2738 if (target > GST_STATE_READY)
2741 /* else we just continue the state change downwards */
2742 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2743 "forcing commit state %s <= %s",
2744 gst_element_state_get_name (target),
2745 gst_element_state_get_name (GST_STATE_READY));
2747 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2750 case GST_STATE_CHANGE_SUCCESS:
2751 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2752 "element changed state SUCCESS");
2753 /* we can commit the state now which will proceeed to
2755 ret = gst_element_continue_state (element, ret);
2757 case GST_STATE_CHANGE_NO_PREROLL:
2758 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2759 "element changed state NO_PREROLL");
2760 /* we can commit the state now which will proceeed to
2762 ret = gst_element_continue_state (element, ret);
2765 goto invalid_return;
2768 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2773 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2781 GST_OBJECT_LOCK (element);
2782 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2783 g_critical ("%s: unknown return value %d from a state change function",
2784 GST_ELEMENT_NAME (element), ret);
2786 /* we are in error now */
2787 ret = GST_STATE_CHANGE_FAILURE;
2788 GST_STATE_RETURN (element) = ret;
2789 GST_OBJECT_UNLOCK (element);
2795 /* gst_iterator_fold functions for pads_activate
2796 * Stop the iterator if activating one pad failed. */
2798 activate_pads (GstPad * pad, GValue * ret, gboolean * active)
2800 gboolean cont = TRUE;
2802 if (!(cont = gst_pad_set_active (pad, *active)))
2803 g_value_set_boolean (ret, FALSE);
2805 /* unref the object that was reffed for us by _fold */
2806 gst_object_unref (pad);
2810 /* set the caps on the pad to NULL */
2812 clear_caps (GstPad * pad, GValue * ret, gboolean * active)
2814 gst_pad_set_caps (pad, NULL);
2815 gst_object_unref (pad);
2819 /* returns false on error or early cutout of the fold, true if all
2820 * pads in @iter were (de)activated successfully. */
2822 iterator_activate_fold_with_resync (GstIterator * iter,
2823 GstIteratorFoldFunction func, gpointer user_data)
2825 GstIteratorResult ires;
2828 /* no need to unset this later, it's just a boolean */
2829 g_value_init (&ret, G_TYPE_BOOLEAN);
2830 g_value_set_boolean (&ret, TRUE);
2833 ires = gst_iterator_fold (iter, func, &ret, user_data);
2835 case GST_ITERATOR_RESYNC:
2836 /* need to reset the result again */
2837 g_value_set_boolean (&ret, TRUE);
2838 gst_iterator_resync (iter);
2840 case GST_ITERATOR_DONE:
2841 /* all pads iterated, return collected value */
2844 /* iterator returned _ERROR or premature end with _OK,
2845 * mark an error and exit */
2846 g_value_set_boolean (&ret, FALSE);
2851 /* return collected value */
2852 return g_value_get_boolean (&ret);
2855 /* is called with STATE_LOCK
2857 * Pads are activated from source pads to sinkpads.
2860 gst_element_pads_activate (GstElement * element, gboolean active)
2865 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2866 "pads_activate with active %d", active);
2868 iter = gst_element_iterate_src_pads (element);
2870 iterator_activate_fold_with_resync (iter,
2871 (GstIteratorFoldFunction) activate_pads, &active);
2872 gst_iterator_free (iter);
2873 if (G_UNLIKELY (!res))
2876 iter = gst_element_iterate_sink_pads (element);
2878 iterator_activate_fold_with_resync (iter,
2879 (GstIteratorFoldFunction) activate_pads, &active);
2880 gst_iterator_free (iter);
2881 if (G_UNLIKELY (!res))
2885 /* clear the caps on all pads, this should never fail */
2886 iter = gst_element_iterate_pads (element);
2888 iterator_activate_fold_with_resync (iter,
2889 (GstIteratorFoldFunction) clear_caps, &active);
2890 gst_iterator_free (iter);
2891 if (G_UNLIKELY (!res))
2895 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2896 "pads_activate successful");
2903 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2904 "source pads_activate failed");
2909 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2910 "sink pads_activate failed");
2915 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2916 "failed to clear caps on pads");
2921 /* is called with STATE_LOCK */
2922 static GstStateChangeReturn
2923 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2925 GstState state, next;
2926 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2929 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2931 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2932 next = GST_STATE_TRANSITION_NEXT (transition);
2934 /* if the element already is in the given state, we just return success */
2935 if (next == GST_STATE_VOID_PENDING || state == next)
2938 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2939 "default handler tries setting state from %s to %s (%04x)",
2940 gst_element_state_get_name (state),
2941 gst_element_state_get_name (next), transition);
2943 switch (transition) {
2944 case GST_STATE_CHANGE_NULL_TO_READY:
2946 case GST_STATE_CHANGE_READY_TO_PAUSED:
2947 if (!gst_element_pads_activate (element, TRUE)) {
2948 result = GST_STATE_CHANGE_FAILURE;
2951 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2953 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2955 case GST_STATE_CHANGE_PAUSED_TO_READY:
2956 case GST_STATE_CHANGE_READY_TO_NULL:
2957 /* deactivate pads in both cases, since they are activated on
2958 ready->paused but the element might not have made it to paused */
2959 if (!gst_element_pads_activate (element, FALSE)) {
2960 result = GST_STATE_CHANGE_FAILURE;
2962 gst_element_set_base_time (element, 0);
2965 /* In null state release the reference to the clock */
2966 GST_OBJECT_LOCK (element);
2967 clock_p = &element->clock;
2968 gst_object_replace ((GstObject **) clock_p, NULL);
2969 GST_OBJECT_UNLOCK (element);
2972 /* this will catch real but unhandled state changes;
2973 * can only be caused by:
2974 * - a new state was added
2975 * - somehow the element was asked to jump across an intermediate state
2977 g_warning ("Unhandled state change from %s to %s",
2978 gst_element_state_get_name (state),
2979 gst_element_state_get_name (next));
2986 GST_OBJECT_LOCK (element);
2987 result = GST_STATE_RETURN (element);
2988 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2989 "element is already in the %s state",
2990 gst_element_state_get_name (state));
2991 GST_OBJECT_UNLOCK (element);
2998 * gst_element_get_factory:
2999 * @element: a #GstElement to request the element factory of.
3001 * Retrieves the factory that was used to create this element.
3003 * Returns: (transfer none): the #GstElementFactory used for creating this
3004 * element. no refcounting is needed.
3007 gst_element_get_factory (GstElement * element)
3009 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
3011 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
3015 gst_element_dispose (GObject * object)
3017 GstElement *element = GST_ELEMENT_CAST (object);
3021 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
3023 if (GST_STATE (element) != GST_STATE_NULL)
3026 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
3027 "removing %d pads", g_list_length (element->pads));
3028 /* first we break all our links with the outside */
3029 while (element->pads && element->pads->data) {
3030 /* don't call _remove_pad with NULL */
3031 gst_element_remove_pad (element, GST_PAD_CAST (element->pads->data));
3033 if (G_UNLIKELY (element->pads != NULL)) {
3034 g_critical ("could not remove pads from element %s",
3035 GST_STR_NULL (GST_OBJECT_NAME (object)));
3038 GST_OBJECT_LOCK (element);
3039 clock_p = &element->clock;
3040 bus_p = &element->bus;
3041 gst_object_replace ((GstObject **) clock_p, NULL);
3042 gst_object_replace ((GstObject **) bus_p, NULL);
3043 GST_OBJECT_UNLOCK (element);
3045 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
3047 G_OBJECT_CLASS (parent_class)->dispose (object);
3056 is_locked = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
3058 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
3060 "You need to explicitly set elements to the NULL state before\n"
3061 "dropping the final reference, to allow them to clean up.\n"
3062 "This problem may also be caused by a refcounting bug in the\n"
3063 "application or some element.\n",
3064 GST_OBJECT_NAME (element),
3065 gst_element_state_get_name (GST_STATE (element)),
3066 is_locked ? " (locked)" : "");
3072 gst_element_finalize (GObject * object)
3074 GstElement *element = GST_ELEMENT_CAST (object);
3076 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
3078 GST_STATE_LOCK (element);
3079 if (element->state_cond)
3080 g_cond_free (element->state_cond);
3081 element->state_cond = NULL;
3082 GST_STATE_UNLOCK (element);
3083 g_static_rec_mutex_free (element->state_lock);
3084 g_slice_free (GStaticRecMutex, element->state_lock);
3085 element->state_lock = NULL;
3087 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
3089 G_OBJECT_CLASS (parent_class)->finalize (object);
3092 #if !defined(GST_DISABLE_LOADSAVE) && !defined(GST_REMOVE_DEPRECATED)
3094 * gst_element_save_thyself:
3095 * @element: a #GstElement to save.
3096 * @parent: the xml parent node.
3098 * Saves the element as part of the given XML structure.
3100 * Returns: the new #xmlNodePtr.
3103 gst_element_save_thyself (GstObject * object, xmlNodePtr parent)
3106 GstElementClass *oclass;
3107 GParamSpec **specs, *spec;
3110 GValue value = { 0, };
3111 GstElement *element;
3113 g_return_val_if_fail (GST_IS_ELEMENT (object), parent);
3115 element = GST_ELEMENT_CAST (object);
3117 oclass = GST_ELEMENT_GET_CLASS (element);
3119 xmlNewChild (parent, NULL, (xmlChar *) "name",
3120 (xmlChar *) GST_ELEMENT_NAME (element));
3122 if (oclass->elementfactory != NULL) {
3123 GstElementFactory *factory = (GstElementFactory *) oclass->elementfactory;
3125 xmlNewChild (parent, NULL, (xmlChar *) "type",
3126 (xmlChar *) GST_PLUGIN_FEATURE (factory)->name);
3130 specs = g_object_class_list_properties (G_OBJECT_GET_CLASS (object), &nspecs);
3132 for (i = 0; i < nspecs; i++) {
3134 if (spec->flags & G_PARAM_READABLE) {
3138 g_value_init (&value, spec->value_type);
3140 g_object_get_property (G_OBJECT (element), spec->name, &value);
3141 param = xmlNewChild (parent, NULL, (xmlChar *) "param", NULL);
3142 xmlNewChild (param, NULL, (xmlChar *) "name", (xmlChar *) spec->name);
3144 if (G_IS_PARAM_SPEC_STRING (spec))
3145 contents = g_value_dup_string (&value);
3146 else if (G_IS_PARAM_SPEC_ENUM (spec))
3147 contents = g_strdup_printf ("%d", g_value_get_enum (&value));
3148 else if (G_IS_PARAM_SPEC_INT64 (spec))
3149 contents = g_strdup_printf ("%" G_GINT64_FORMAT,
3150 g_value_get_int64 (&value));
3151 else if (GST_VALUE_HOLDS_STRUCTURE (&value)) {
3152 if (g_value_get_boxed (&value) != NULL) {
3153 contents = g_strdup_value_contents (&value);
3155 contents = g_strdup ("NULL");
3158 contents = g_strdup_value_contents (&value);
3160 xmlNewChild (param, NULL, (xmlChar *) "value", (xmlChar *) contents);
3163 g_value_unset (&value);
3169 pads = g_list_last (GST_ELEMENT_PADS (element));
3172 GstPad *pad = GST_PAD_CAST (pads->data);
3174 /* figure out if it's a direct pad or a ghostpad */
3175 if (GST_ELEMENT_CAST (GST_OBJECT_PARENT (pad)) == element) {
3176 xmlNodePtr padtag = xmlNewChild (parent, NULL, (xmlChar *) "pad", NULL);
3178 gst_object_save_thyself (GST_OBJECT_CAST (pad), padtag);
3180 pads = g_list_previous (pads);
3187 gst_element_restore_thyself (GstObject * object, xmlNodePtr self)
3189 xmlNodePtr children;
3190 GstElement *element;
3192 gchar *value = NULL;
3194 element = GST_ELEMENT_CAST (object);
3195 g_return_if_fail (element != NULL);
3198 children = self->xmlChildrenNode;
3200 if (!strcmp ((char *) children->name, "param")) {
3201 xmlNodePtr child = children->xmlChildrenNode;
3204 if (!strcmp ((char *) child->name, "name")) {
3205 name = (gchar *) xmlNodeGetContent (child);
3206 } else if (!strcmp ((char *) child->name, "value")) {
3207 value = (gchar *) xmlNodeGetContent (child);
3209 child = child->next;
3211 /* FIXME: can this just be g_object_set ? */
3212 gst_util_set_object_arg (G_OBJECT (element), name, value);
3213 /* g_object_set (G_OBJECT (element), name, value, NULL); */
3217 children = children->next;
3221 children = self->xmlChildrenNode;
3223 if (!strcmp ((char *) children->name, "pad")) {
3224 gst_pad_load_and_link (children, GST_OBJECT_CAST (element));
3226 children = children->next;
3229 if (GST_OBJECT_CLASS (parent_class)->restore_thyself)
3230 (GST_OBJECT_CLASS (parent_class)->restore_thyself) (object, self);
3232 #endif /* GST_DISABLE_LOADSAVE */
3235 gst_element_set_bus_func (GstElement * element, GstBus * bus)
3239 g_return_if_fail (GST_IS_ELEMENT (element));
3241 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
3243 GST_OBJECT_LOCK (element);
3244 bus_p = &GST_ELEMENT_BUS (element);
3245 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
3246 GST_OBJECT_UNLOCK (element);
3250 * gst_element_set_bus:
3251 * @element: a #GstElement to set the bus of.
3252 * @bus: (transfer none): the #GstBus to set.
3254 * Sets the bus of the element. Increases the refcount on the bus.
3255 * For internal use only, unless you're testing elements.
3260 gst_element_set_bus (GstElement * element, GstBus * bus)
3262 GstElementClass *oclass;
3264 g_return_if_fail (GST_IS_ELEMENT (element));
3266 oclass = GST_ELEMENT_GET_CLASS (element);
3268 if (oclass->set_bus)
3269 oclass->set_bus (element, bus);
3273 * gst_element_get_bus:
3274 * @element: a #GstElement to get the bus of.
3276 * Returns the bus of the element. Note that only a #GstPipeline will provide a
3277 * bus for the application.
3279 * Returns: (transfer full): the element's #GstBus. unref after usage.
3284 gst_element_get_bus (GstElement * element)
3286 GstBus *result = NULL;
3288 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3290 GST_OBJECT_LOCK (element);
3291 if ((result = GST_ELEMENT_BUS (element)))
3292 gst_object_ref (result);
3293 GST_OBJECT_UNLOCK (element);
3295 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,