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 "gstelementmetadata.h"
86 #include "gstenumtypes.h"
88 #include "gstmarshal.h"
94 #include "gst-i18n-lib.h"
96 /* Element signals and args */
112 static void gst_element_class_init (GstElementClass * klass);
113 static void gst_element_init (GstElement * element);
114 static void gst_element_base_class_init (gpointer g_class);
115 static void gst_element_base_class_finalize (gpointer g_class);
117 static void gst_element_dispose (GObject * object);
118 static void gst_element_finalize (GObject * object);
120 static GstStateChangeReturn gst_element_change_state_func (GstElement * element,
121 GstStateChange transition);
122 static GstStateChangeReturn gst_element_get_state_func (GstElement * element,
123 GstState * state, GstState * pending, GstClockTime timeout);
124 static GstStateChangeReturn gst_element_set_state_func (GstElement * element,
126 static void gst_element_set_bus_func (GstElement * element, GstBus * bus);
128 static gboolean gst_element_default_send_event (GstElement * element,
130 static gboolean gst_element_default_query (GstElement * element,
133 static GstPadTemplate
134 * gst_element_class_get_request_pad_template (GstElementClass *
135 element_class, const gchar * name);
137 static GstObjectClass *parent_class = NULL;
138 static guint gst_element_signals[LAST_SIGNAL] = { 0 };
140 /* this is used in gstelementfactory.c:gst_element_register() */
141 GQuark _gst_elementclass_factory = 0;
144 gst_element_get_type (void)
146 static volatile gsize gst_element_type = 0;
148 if (g_once_init_enter (&gst_element_type)) {
150 static const GTypeInfo element_info = {
151 sizeof (GstElementClass),
152 gst_element_base_class_init,
153 gst_element_base_class_finalize,
154 (GClassInitFunc) gst_element_class_init,
159 (GInstanceInitFunc) gst_element_init,
163 _type = g_type_register_static (GST_TYPE_OBJECT, "GstElement",
164 &element_info, G_TYPE_FLAG_ABSTRACT);
166 _gst_elementclass_factory =
167 g_quark_from_static_string ("GST_ELEMENTCLASS_FACTORY");
168 g_once_init_leave (&gst_element_type, _type);
170 return gst_element_type;
174 gst_element_class_init (GstElementClass * klass)
176 GObjectClass *gobject_class;
177 GstObjectClass *gstobject_class;
179 gobject_class = (GObjectClass *) klass;
180 gstobject_class = (GstObjectClass *) klass;
182 parent_class = g_type_class_peek_parent (klass);
185 * GstElement::pad-added:
186 * @gstelement: the object which received the signal
187 * @new_pad: the pad that has been added
189 * a new #GstPad has been added to the element. Note that this signal will
190 * usually be emitted from the context of the streaming thread. Also keep in
191 * mind that if you add new elements to the pipeline in the signal handler
192 * you will need to set them to the desired target state with
193 * gst_element_set() or gst_element_sync_state_with_parent().
195 gst_element_signals[PAD_ADDED] =
196 g_signal_new ("pad-added", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
197 G_STRUCT_OFFSET (GstElementClass, pad_added), NULL, NULL,
198 gst_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GST_TYPE_PAD);
200 * GstElement::pad-removed:
201 * @gstelement: the object which received the signal
202 * @old_pad: the pad that has been removed
204 * a #GstPad has been removed from the element
206 gst_element_signals[PAD_REMOVED] =
207 g_signal_new ("pad-removed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
208 G_STRUCT_OFFSET (GstElementClass, pad_removed), NULL, NULL,
209 gst_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GST_TYPE_PAD);
211 * GstElement::no-more-pads:
212 * @gstelement: the object which received the signal
214 * This signals that the element will not generate more dynamic pads.
215 * Note that this signal will usually be emitted from the context of
216 * the streaming thread.
218 gst_element_signals[NO_MORE_PADS] =
219 g_signal_new ("no-more-pads", G_TYPE_FROM_CLASS (klass),
220 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstElementClass, no_more_pads), NULL,
221 NULL, gst_marshal_VOID__VOID, G_TYPE_NONE, 0);
223 gobject_class->dispose = gst_element_dispose;
224 gobject_class->finalize = gst_element_finalize;
226 klass->change_state = GST_DEBUG_FUNCPTR (gst_element_change_state_func);
227 klass->set_state = GST_DEBUG_FUNCPTR (gst_element_set_state_func);
228 klass->get_state = GST_DEBUG_FUNCPTR (gst_element_get_state_func);
229 klass->set_bus = GST_DEBUG_FUNCPTR (gst_element_set_bus_func);
230 klass->query = GST_DEBUG_FUNCPTR (gst_element_default_query);
231 klass->send_event = GST_DEBUG_FUNCPTR (gst_element_default_send_event);
232 klass->numpadtemplates = 0;
234 klass->elementfactory = NULL;
238 gst_element_base_class_init (gpointer g_class)
240 GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
241 GList *node, *padtemplates;
243 /* Copy the element details here so elements can inherit the
244 * details from their base class and classes only need to set
245 * the details in class_init instead of base_init */
246 element_class->metadata =
247 element_class->metadata ? gst_structure_copy (element_class->metadata) :
248 gst_structure_empty_new ("metadata");
250 /* Copy the pad templates so elements inherit them
251 * from their base class but elements can add pad templates in class_init
252 * instead of base_init.
254 /* FIXME: Do we consider GstPadTemplates as immutable? If so we can
255 * simply ref them instead of copying.
257 padtemplates = g_list_copy (element_class->padtemplates);
258 for (node = padtemplates; node != NULL; node = node->next) {
259 GstPadTemplate *tmpl = (GstPadTemplate *) node->data;
260 node->data = gst_pad_template_new (tmpl->name_template,
261 tmpl->direction, tmpl->presence, gst_caps_copy (tmpl->caps));
263 element_class->padtemplates = padtemplates;
265 /* set the factory, see gst_element_register() */
266 element_class->elementfactory =
267 g_type_get_qdata (G_TYPE_FROM_CLASS (element_class),
268 _gst_elementclass_factory);
269 GST_DEBUG ("type %s : factory %p", G_OBJECT_CLASS_NAME (element_class),
270 element_class->elementfactory);
274 gst_element_base_class_finalize (gpointer g_class)
276 GstElementClass *klass = GST_ELEMENT_CLASS (g_class);
278 g_list_foreach (klass->padtemplates, (GFunc) gst_object_unref, NULL);
279 g_list_free (klass->padtemplates);
281 gst_structure_free (klass->metadata);
285 gst_element_init (GstElement * element)
287 GST_STATE (element) = GST_STATE_NULL;
288 GST_STATE_TARGET (element) = GST_STATE_NULL;
289 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
290 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
291 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
293 /* FIXME 0.11: Store this directly in the instance struct */
294 element->state_lock = g_slice_new (GStaticRecMutex);
295 g_static_rec_mutex_init (element->state_lock);
296 element->state_cond = g_cond_new ();
300 * gst_element_release_request_pad:
301 * @element: a #GstElement to release the request pad of.
302 * @pad: the #GstPad to release.
304 * Makes the element free the previously requested pad as obtained
305 * with gst_element_get_request_pad().
307 * This does not unref the pad. If the pad was created by using
308 * gst_element_get_request_pad(), gst_element_release_request_pad() needs to be
309 * followed by gst_object_unref() to free the @pad.
314 gst_element_release_request_pad (GstElement * element, GstPad * pad)
316 GstElementClass *oclass;
318 g_return_if_fail (GST_IS_ELEMENT (element));
319 g_return_if_fail (GST_IS_PAD (pad));
321 oclass = GST_ELEMENT_GET_CLASS (element);
323 /* if the element implements a custom release function we call that, else we
324 * simply remove the pad from the element */
325 if (oclass->release_pad)
326 (oclass->release_pad) (element, pad);
328 gst_element_remove_pad (element, pad);
332 * gst_element_requires_clock:
333 * @element: a #GstElement to query
335 * Query if the element requires a clock.
337 * Returns: %TRUE if the element requires a clock
342 gst_element_requires_clock (GstElement * element)
346 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
348 result = (GST_ELEMENT_GET_CLASS (element)->set_clock != NULL);
354 * gst_element_provides_clock:
355 * @element: a #GstElement to query
357 * Query if the element provides a clock. A #GstClock provided by an
358 * element can be used as the global #GstClock for the pipeline.
359 * An element that can provide a clock is only required to do so in the PAUSED
360 * state, this means when it is fully negotiated and has allocated the resources
361 * to operate the clock.
363 * Returns: %TRUE if the element provides a clock
368 gst_element_provides_clock (GstElement * element)
372 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
374 result = (GST_ELEMENT_GET_CLASS (element)->provide_clock != NULL);
380 * gst_element_provide_clock:
381 * @element: a #GstElement to query
383 * Get the clock provided by the given element.
384 * <note>An element is only required to provide a clock in the PAUSED
385 * state. Some elements can provide a clock in other states.</note>
387 * Returns: (transfer full): the GstClock provided by the element or %NULL
388 * if no clock could be provided. Unref after usage.
393 gst_element_provide_clock (GstElement * element)
395 GstClock *result = NULL;
396 GstElementClass *oclass;
398 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
400 oclass = GST_ELEMENT_GET_CLASS (element);
402 if (oclass->provide_clock)
403 result = oclass->provide_clock (element);
409 * gst_element_set_clock:
410 * @element: a #GstElement to set the clock for.
411 * @clock: the #GstClock to set for the element.
413 * Sets the clock for the element. This function increases the
414 * refcount on the clock. Any previously set clock on the object
417 * Returns: %TRUE if the element accepted the clock. An element can refuse a
418 * clock when it, for example, is not able to slave its internal clock to the
419 * @clock or when it requires a specific clock to operate.
424 gst_element_set_clock (GstElement * element, GstClock * clock)
426 GstElementClass *oclass;
430 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
431 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
433 oclass = GST_ELEMENT_GET_CLASS (element);
435 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
437 if (oclass->set_clock)
438 res = oclass->set_clock (element, clock);
441 /* only update the clock pointer if the element accepted the clock */
442 GST_OBJECT_LOCK (element);
443 clock_p = &element->clock;
444 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
445 GST_OBJECT_UNLOCK (element);
451 * gst_element_get_clock:
452 * @element: a #GstElement to get the clock of.
454 * Gets the currently configured clock of the element. This is the clock as was
455 * last set with gst_element_set_clock().
457 * Returns: (transfer full): the #GstClock of the element. unref after usage.
462 gst_element_get_clock (GstElement * element)
466 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
468 GST_OBJECT_LOCK (element);
469 if ((result = element->clock))
470 gst_object_ref (result);
471 GST_OBJECT_UNLOCK (element);
477 * gst_element_set_base_time:
478 * @element: a #GstElement.
479 * @time: the base time to set.
481 * Set the base time of an element. See gst_element_get_base_time().
486 gst_element_set_base_time (GstElement * element, GstClockTime time)
490 g_return_if_fail (GST_IS_ELEMENT (element));
492 GST_OBJECT_LOCK (element);
493 old = element->base_time;
494 element->base_time = time;
495 GST_OBJECT_UNLOCK (element);
497 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
498 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
499 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
503 * gst_element_get_base_time:
504 * @element: a #GstElement.
506 * Returns the base time of the element. The base time is the
507 * absolute time of the clock when this element was last put to
508 * PLAYING. Subtracting the base time from the clock time gives
509 * the running time of the element.
511 * Returns: the base time of the element.
516 gst_element_get_base_time (GstElement * element)
520 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
522 GST_OBJECT_LOCK (element);
523 result = element->base_time;
524 GST_OBJECT_UNLOCK (element);
530 * gst_element_set_start_time:
531 * @element: a #GstElement.
532 * @time: the base time to set.
534 * Set the start time of an element. The start time of the element is the
535 * running time of the element when it last went to the PAUSED state. In READY
536 * or after a flushing seek, it is set to 0.
538 * Toplevel elements like #GstPipeline will manage the start_time and
539 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
540 * on such a toplevel element will disable the distribution of the base_time to
541 * the children and can be useful if the application manages the base_time
542 * itself, for example if you want to synchronize capture from multiple
543 * pipelines, and you can also ensure that the pipelines have the same clock.
550 gst_element_set_start_time (GstElement * element, GstClockTime time)
554 g_return_if_fail (GST_IS_ELEMENT (element));
556 GST_OBJECT_LOCK (element);
557 old = GST_ELEMENT_START_TIME (element);
558 GST_ELEMENT_START_TIME (element) = time;
559 GST_OBJECT_UNLOCK (element);
561 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
562 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
563 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
567 * gst_element_get_start_time:
568 * @element: a #GstElement.
570 * Returns the start time of the element. The start time is the
571 * running time of the clock when this element was last put to PAUSED.
573 * Usually the start_time is managed by a toplevel element such as
578 * Returns: the start time of the element.
583 gst_element_get_start_time (GstElement * element)
587 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
589 GST_OBJECT_LOCK (element);
590 result = GST_ELEMENT_START_TIME (element);
591 GST_OBJECT_UNLOCK (element);
597 * gst_element_is_indexable:
598 * @element: a #GstElement.
600 * Queries if the element can be indexed.
602 * Returns: TRUE if the element can be indexed.
607 gst_element_is_indexable (GstElement * element)
611 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
613 result = (GST_ELEMENT_GET_CLASS (element)->set_index != NULL);
619 * gst_element_set_index:
620 * @element: a #GstElement.
621 * @index: (transfer none): a #GstIndex.
623 * Set @index on the element. The refcount of the index
624 * will be increased, any previously set index is unreffed.
629 gst_element_set_index (GstElement * element, GstIndex * index)
631 GstElementClass *oclass;
633 g_return_if_fail (GST_IS_ELEMENT (element));
634 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
636 oclass = GST_ELEMENT_GET_CLASS (element);
638 if (oclass->set_index)
639 oclass->set_index (element, index);
643 * gst_element_get_index:
644 * @element: a #GstElement.
646 * Gets the index from the element.
648 * Returns: (transfer full): a #GstIndex or %NULL when no index was set on the
649 * element. unref after usage.
654 gst_element_get_index (GstElement * element)
656 GstElementClass *oclass;
657 GstIndex *result = NULL;
659 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
661 oclass = GST_ELEMENT_GET_CLASS (element);
663 if (oclass->get_index)
664 result = oclass->get_index (element);
670 * gst_element_add_pad:
671 * @element: a #GstElement to add the pad to.
672 * @pad: (transfer full): the #GstPad to add to the element.
674 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
675 * see gst_object_set_parent() for refcounting information.
677 * Pads are not automatically activated so elements should perform the needed
678 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
679 * state. See gst_pad_set_active() for more information about activating pads.
681 * The pad and the element should be unlocked when calling this function.
683 * This function will emit the #GstElement::pad-added signal on the element.
685 * Returns: %TRUE if the pad could be added. This function can fail when
686 * a pad with the same name already existed or the pad already had another
692 gst_element_add_pad (GstElement * element, GstPad * pad)
697 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
698 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
700 /* locking pad to look at the name */
701 GST_OBJECT_LOCK (pad);
702 pad_name = g_strdup (GST_PAD_NAME (pad));
703 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
704 GST_STR_NULL (pad_name));
705 flushing = GST_PAD_IS_FLUSHING (pad);
706 GST_OBJECT_UNLOCK (pad);
708 /* then check to see if there's already a pad by that name here */
709 GST_OBJECT_LOCK (element);
710 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
713 /* try to set the pad's parent */
714 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
715 GST_OBJECT_CAST (element))))
718 /* check for flushing pads */
719 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
720 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
721 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
722 "use gst_pad_set_active(pad,TRUE) before adding it.",
723 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
725 GST_OBJECT_LOCK (pad);
726 GST_PAD_UNSET_FLUSHING (pad);
727 GST_OBJECT_UNLOCK (pad);
732 /* add it to the list */
733 switch (gst_pad_get_direction (pad)) {
735 element->srcpads = g_list_prepend (element->srcpads, pad);
736 element->numsrcpads++;
739 element->sinkpads = g_list_prepend (element->sinkpads, pad);
740 element->numsinkpads++;
745 element->pads = g_list_prepend (element->pads, pad);
747 element->pads_cookie++;
748 GST_OBJECT_UNLOCK (element);
750 /* emit the PAD_ADDED signal */
751 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
758 g_critical ("Padname %s is not unique in element %s, not adding",
759 pad_name, GST_ELEMENT_NAME (element));
760 GST_OBJECT_UNLOCK (element);
767 ("Pad %s already has parent when trying to add to element %s",
768 pad_name, GST_ELEMENT_NAME (element));
769 GST_OBJECT_UNLOCK (element);
775 GST_OBJECT_LOCK (pad);
777 ("Trying to add pad %s to element %s, but it has no direction",
778 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
779 GST_OBJECT_UNLOCK (pad);
780 GST_OBJECT_UNLOCK (element);
786 * gst_element_remove_pad:
787 * @element: a #GstElement to remove pad from.
788 * @pad: (transfer none): the #GstPad to remove from the element.
790 * Removes @pad from @element. @pad will be destroyed if it has not been
791 * referenced elsewhere using gst_object_unparent().
793 * This function is used by plugin developers and should not be used
794 * by applications. Pads that were dynamically requested from elements
795 * with gst_element_get_request_pad() should be released with the
796 * gst_element_release_request_pad() function instead.
798 * Pads are not automatically deactivated so elements should perform the needed
799 * steps to deactivate the pad in case this pad is removed in the PAUSED or
800 * PLAYING state. See gst_pad_set_active() for more information about
803 * The pad and the element should be unlocked when calling this function.
805 * This function will emit the #GstElement::pad-removed signal on the element.
807 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
808 * pad does not belong to the provided element.
813 gst_element_remove_pad (GstElement * element, GstPad * pad)
817 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
818 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
820 /* locking pad to look at the name and parent */
821 GST_OBJECT_LOCK (pad);
822 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
823 GST_STR_NULL (GST_PAD_NAME (pad)));
825 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
827 GST_OBJECT_UNLOCK (pad);
830 if ((peer = gst_pad_get_peer (pad))) {
831 /* window for MT unsafeness, someone else could unlink here
832 * and then we call unlink with wrong pads. The unlink
833 * function would catch this and safely return failed. */
834 if (GST_PAD_IS_SRC (pad))
835 gst_pad_unlink (pad, peer);
837 gst_pad_unlink (peer, pad);
839 gst_object_unref (peer);
842 GST_OBJECT_LOCK (element);
843 /* remove it from the list */
844 switch (gst_pad_get_direction (pad)) {
846 element->srcpads = g_list_remove (element->srcpads, pad);
847 element->numsrcpads--;
850 element->sinkpads = g_list_remove (element->sinkpads, pad);
851 element->numsinkpads--;
854 g_critical ("Removing pad without direction???");
857 element->pads = g_list_remove (element->pads, pad);
859 element->pads_cookie++;
860 GST_OBJECT_UNLOCK (element);
862 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
863 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
865 gst_object_unparent (GST_OBJECT_CAST (pad));
872 /* FIXME, locking order? */
873 GST_OBJECT_LOCK (element);
874 g_critical ("Padname %s:%s does not belong to element %s when removing",
875 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
876 GST_OBJECT_UNLOCK (element);
877 GST_OBJECT_UNLOCK (pad);
883 * gst_element_no_more_pads:
884 * @element: a #GstElement
886 * Use this function to signal that the element does not expect any more pads
887 * to show up in the current pipeline. This function should be called whenever
888 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
889 * pad templates use this in combination with autopluggers to figure out that
890 * the element is done initializing its pads.
892 * This function emits the #GstElement::no-more-pads signal.
897 gst_element_no_more_pads (GstElement * element)
899 g_return_if_fail (GST_IS_ELEMENT (element));
901 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
905 pad_compare_name (GstPad * pad1, const gchar * name)
909 GST_OBJECT_LOCK (pad1);
910 result = strcmp (GST_PAD_NAME (pad1), name);
911 GST_OBJECT_UNLOCK (pad1);
917 * gst_element_get_static_pad:
918 * @element: a #GstElement to find a static pad of.
919 * @name: the name of the static #GstPad to retrieve.
921 * Retrieves a pad from @element by name. This version only retrieves
922 * already-existing (i.e. 'static') pads.
924 * Returns: (transfer full): the requested #GstPad if found, otherwise %NULL.
930 gst_element_get_static_pad (GstElement * element, const gchar * name)
933 GstPad *result = NULL;
935 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
936 g_return_val_if_fail (name != NULL, NULL);
938 GST_OBJECT_LOCK (element);
940 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
942 result = GST_PAD_CAST (find->data);
943 gst_object_ref (result);
946 if (result == NULL) {
947 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
948 name, GST_ELEMENT_NAME (element));
950 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
951 GST_ELEMENT_NAME (element), name);
953 GST_OBJECT_UNLOCK (element);
959 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
960 const gchar * name, const GstCaps * caps)
962 GstPad *newpad = NULL;
963 GstElementClass *oclass;
965 oclass = GST_ELEMENT_GET_CLASS (element);
967 #ifndef G_DISABLE_CHECKS
968 /* Some sanity checking here */
972 /* Is this the template name? */
973 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
974 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
976 const gchar *str, *data;
979 /* Otherwise check if it's a valid name for the name template */
980 str = strchr (templ->name_template, '%');
981 g_return_val_if_fail (str != NULL, NULL);
982 g_return_val_if_fail (strncmp (templ->name_template, name,
983 str - templ->name_template) == 0, NULL);
984 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
986 data = name + (str - templ->name_template);
988 /* Can either be %s or %d or %u, do sanity checking for %d */
989 if (*(str + 1) == 'd') {
993 tmp = g_ascii_strtoll (data, &endptr, 10);
994 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
995 && *endptr == '\0', NULL);
996 } else if (*(str + 1) == 'u') {
1000 tmp = g_ascii_strtoull (data, &endptr, 10);
1001 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
1005 pad = gst_element_get_static_pad (element, name);
1007 gst_object_unref (pad);
1008 /* FIXME 0.11: Change this to g_return_val_if_fail() */
1009 g_critical ("Element %s already has a pad named %s, the behaviour of "
1010 " gst_element_get_request_pad() for existing pads is undefined!",
1011 GST_ELEMENT_NAME (element), name);
1016 if (oclass->request_new_pad_full)
1017 newpad = (oclass->request_new_pad_full) (element, templ, name, caps);
1018 else if (oclass->request_new_pad)
1019 newpad = (oclass->request_new_pad) (element, templ, name);
1022 gst_object_ref (newpad);
1028 * gst_element_get_request_pad:
1029 * @element: a #GstElement to find a request pad of.
1030 * @name: the name of the request #GstPad to retrieve.
1032 * Retrieves a pad from the element by name. This version only retrieves
1033 * request pads. The pad should be released with
1034 * gst_element_release_request_pad().
1036 * This method is slow and will be deprecated in the future. New code should
1037 * use gst_element_request_pad() with the requested template.
1039 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1040 * Release after usage.
1043 gst_element_get_request_pad (GstElement * element, const gchar * name)
1045 GstPadTemplate *templ = NULL;
1047 const gchar *req_name = NULL;
1048 gboolean templ_found = FALSE;
1051 gchar *str, *endptr = NULL;
1052 GstElementClass *class;
1054 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1055 g_return_val_if_fail (name != NULL, NULL);
1057 class = GST_ELEMENT_GET_CLASS (element);
1059 /* if the name contains a %, we assume it's the complete template name. Get
1060 * the template and try to get a pad */
1061 if (strstr (name, "%")) {
1062 templ = gst_element_class_get_request_pad_template (class, name);
1067 /* there is no % in the name, try to find a matching template */
1068 list = class->padtemplates;
1069 while (!templ_found && list) {
1070 templ = (GstPadTemplate *) list->data;
1071 if (templ->presence == GST_PAD_REQUEST) {
1072 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1073 templ->name_template);
1074 /* see if we find an exact match */
1075 if (strcmp (name, templ->name_template) == 0) {
1080 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1081 and %d and %u, occurring at the end of the name_template, are the only
1083 else if ((str = strchr (templ->name_template, '%'))
1084 && strncmp (templ->name_template, name,
1085 str - templ->name_template) == 0
1086 && strlen (name) > str - templ->name_template) {
1087 data = name + (str - templ->name_template);
1088 if (*(str + 1) == 'd') {
1092 tmp = strtol (data, &endptr, 10);
1093 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1099 } else if (*(str + 1) == 'u') {
1103 tmp = strtoul (data, &endptr, 10);
1104 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1124 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1130 * gst_element_request_pad:
1131 * @element: a #GstElement to find a request pad of.
1132 * @templ: a #GstPadTemplate of which we want a pad of.
1133 * @name: (transfer none) (allow-none): the name of the request #GstPad
1134 * to retrieve. Can be %NULL.
1135 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1136 * request. Can be %NULL.
1138 * Retrieves a request pad from the element according to the provided template.
1140 * If the @caps are specified and the element implements thew new
1141 * request_new_pad_full virtual method, the element will use them to select
1142 * which pad to create.
1144 * The pad should be released with gst_element_release_request_pad().
1146 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1147 * Release after usage.
1152 gst_element_request_pad (GstElement * element,
1153 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1155 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1156 g_return_val_if_fail (templ != NULL, NULL);
1158 return _gst_element_request_pad (element, templ, name, caps);
1162 * gst_element_get_pad:
1163 * @element: a #GstElement.
1164 * @name: the name of the pad to retrieve.
1166 * Retrieves a pad from @element by name. Tries gst_element_get_static_pad()
1167 * first, then gst_element_get_request_pad().
1169 * Deprecated: This function is deprecated as it's unclear if the reference
1170 * to the result pad should be released with gst_object_unref() in case of a static pad
1171 * or gst_element_release_request_pad() in case of a request pad.
1172 * Use gst_element_get_static_pad() or gst_element_get_request_pad() instead.
1174 * Returns: (transfer full): the #GstPad if found, otherwise %NULL. Unref or Release after usage,
1175 * depending on the type of the pad.
1177 #ifndef GST_REMOVE_DEPRECATED
1178 #ifdef GST_DISABLE_DEPRECATED
1179 GstPad *gst_element_get_pad (GstElement * element, const gchar * name);
1182 gst_element_get_pad (GstElement * element, const gchar * name)
1186 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1187 g_return_val_if_fail (name != NULL, NULL);
1189 pad = gst_element_get_static_pad (element, name);
1191 pad = gst_element_get_request_pad (element, name);
1195 #endif /* GST_REMOVE_DEPRECATED */
1197 static GstIteratorItem
1198 iterate_pad (GstIterator * it, GstPad * pad)
1200 gst_object_ref (pad);
1201 return GST_ITERATOR_ITEM_PASS;
1204 static GstIterator *
1205 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1207 GstIterator *result;
1209 GST_OBJECT_LOCK (element);
1210 gst_object_ref (element);
1211 result = gst_iterator_new_list (GST_TYPE_PAD,
1212 GST_OBJECT_GET_LOCK (element),
1213 &element->pads_cookie,
1216 (GstIteratorItemFunction) iterate_pad,
1217 (GstIteratorDisposeFunction) gst_object_unref);
1218 GST_OBJECT_UNLOCK (element);
1224 * gst_element_iterate_pads:
1225 * @element: a #GstElement to iterate pads of.
1227 * Retrieves an iterattor of @element's pads. The iterator should
1228 * be freed after usage.
1230 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1236 gst_element_iterate_pads (GstElement * element)
1238 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1240 return gst_element_iterate_pad_list (element, &element->pads);
1244 * gst_element_iterate_src_pads:
1245 * @element: a #GstElement.
1247 * Retrieves an iterator of @element's source pads.
1249 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1255 gst_element_iterate_src_pads (GstElement * element)
1257 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1259 return gst_element_iterate_pad_list (element, &element->srcpads);
1263 * gst_element_iterate_sink_pads:
1264 * @element: a #GstElement.
1266 * Retrieves an iterator of @element's sink pads.
1268 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1274 gst_element_iterate_sink_pads (GstElement * element)
1276 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1278 return gst_element_iterate_pad_list (element, &element->sinkpads);
1282 * gst_element_class_add_pad_template:
1283 * @klass: the #GstElementClass to add the pad template to.
1284 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1286 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1287 * functions of classes. If a pad template with the same name as an already
1288 * existing one is added the old one is replaced by the new one.
1292 gst_element_class_add_pad_template (GstElementClass * klass,
1293 GstPadTemplate * templ)
1295 GList *template_list = klass->padtemplates;
1297 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1298 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1300 /* If we already have a pad template with the same name replace the
1302 while (template_list) {
1303 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1305 /* Found pad with the same name, replace and return */
1306 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1307 gst_object_unref (padtempl);
1308 template_list->data = templ;
1311 template_list = g_list_next (template_list);
1314 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1315 klass->numpadtemplates++;
1319 * gst_element_class_add_metadata:
1320 * @klass: class to set metadata for
1321 * @key: the key to set
1322 * @value: the value to set
1324 * Set @key with @value as metadata in @klass.
1327 gst_element_class_add_metadata (GstElementClass * klass,
1328 const gchar * key, const gchar * value)
1330 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1331 g_return_if_fail (key != NULL);
1332 g_return_if_fail (value != NULL);
1334 gst_structure_set ((GstStructure *) klass->metadata,
1335 key, G_TYPE_STRING, value, NULL);
1339 * gst_element_class_set_metadata:
1340 * @klass: class to set metadata for
1341 * @longname: The long English name of the element. E.g. "File Sink"
1342 * @classification: String describing the type of element, as an unordered list
1343 * separated with slashes ('/'). See draft-klass.txt of the design docs
1344 * for more details and common types. E.g: "Sink/File"
1345 * @description: Sentence describing the purpose of the element.
1346 * E.g: "Write stream to a file"
1347 * @author: Name and contact details of the author(s). Use \n to separate
1348 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1350 * Sets the detailed information for a #GstElementClass.
1351 * <note>This function is for use in _class_init functions only.</note>
1354 gst_element_class_set_metadata (GstElementClass * klass,
1355 const gchar * longname, const gchar * classification,
1356 const gchar * description, const gchar * author)
1358 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1360 gst_structure_set ((GstStructure *) klass->metadata,
1361 GST_ELEMENT_METADATA_LONGNAME, G_TYPE_STRING, longname,
1362 GST_ELEMENT_METADATA_KLASS, G_TYPE_STRING, classification,
1363 GST_ELEMENT_METADATA_DESCRIPTION, G_TYPE_STRING, description,
1364 GST_ELEMENT_METADATA_AUTHOR, G_TYPE_STRING, author, NULL);
1368 * gst_element_class_get_pad_template_list:
1369 * @element_class: a #GstElementClass to get pad templates of.
1371 * Retrieves a list of the pad templates associated with @element_class. The
1372 * list must not be modified by the calling code.
1373 * <note>If you use this function in the #GInstanceInitFunc of an object class
1374 * that has subclasses, make sure to pass the g_class parameter of the
1375 * #GInstanceInitFunc here.</note>
1377 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1381 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1383 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1385 return element_class->padtemplates;
1389 * gst_element_class_get_pad_template:
1390 * @element_class: a #GstElementClass to get the pad template of.
1391 * @name: the name of the #GstPadTemplate to get.
1393 * Retrieves a padtemplate from @element_class with the given name.
1394 * <note>If you use this function in the #GInstanceInitFunc of an object class
1395 * that has subclasses, make sure to pass the g_class parameter of the
1396 * #GInstanceInitFunc here.</note>
1398 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1399 * if none was found. No unreferencing is necessary.
1402 gst_element_class_get_pad_template (GstElementClass *
1403 element_class, const gchar * name)
1407 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1408 g_return_val_if_fail (name != NULL, NULL);
1410 padlist = element_class->padtemplates;
1413 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1415 if (strcmp (padtempl->name_template, name) == 0)
1418 padlist = g_list_next (padlist);
1424 static GstPadTemplate *
1425 gst_element_class_get_request_pad_template (GstElementClass *
1426 element_class, const gchar * name)
1428 GstPadTemplate *tmpl;
1430 tmpl = gst_element_class_get_pad_template (element_class, name);
1431 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1437 /* get a random pad on element of the given direction.
1438 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1441 gst_element_get_random_pad (GstElement * element,
1442 gboolean need_linked, GstPadDirection dir)
1444 GstPad *result = NULL;
1447 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1451 GST_OBJECT_LOCK (element);
1452 pads = element->srcpads;
1455 GST_OBJECT_LOCK (element);
1456 pads = element->sinkpads;
1459 goto wrong_direction;
1461 for (; pads; pads = g_list_next (pads)) {
1462 GstPad *pad = GST_PAD_CAST (pads->data);
1464 GST_OBJECT_LOCK (pad);
1465 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1466 GST_DEBUG_PAD_NAME (pad));
1468 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1469 /* if we require a linked pad, and it is not linked, continue the
1471 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1472 GST_DEBUG_PAD_NAME (pad));
1473 GST_OBJECT_UNLOCK (pad);
1476 /* found a pad, stop search */
1477 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1478 GST_DEBUG_PAD_NAME (pad));
1479 GST_OBJECT_UNLOCK (pad);
1485 gst_object_ref (result);
1487 GST_OBJECT_UNLOCK (element);
1491 /* ERROR handling */
1494 g_warning ("unknown pad direction %d", dir);
1500 gst_element_default_send_event (GstElement * element, GstEvent * event)
1502 gboolean result = FALSE;
1505 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1506 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1507 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1510 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1511 "pushing %s event to random %s pad %s:%s",
1512 GST_EVENT_TYPE_NAME (event),
1513 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1514 GST_DEBUG_PAD_NAME (pad));
1516 result = gst_pad_push_event (pad, event);
1517 gst_object_unref (pad);
1519 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1520 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1521 gst_event_unref (event);
1527 * gst_element_send_event:
1528 * @element: a #GstElement to send the event to.
1529 * @event: (transfer full): the #GstEvent to send to the element.
1531 * Sends an event to an element. If the element doesn't implement an
1532 * event handler, the event will be pushed on a random linked sink pad for
1533 * upstream events or a random linked source pad for downstream events.
1535 * This function takes owership of the provided event so you should
1536 * gst_event_ref() it if you want to reuse the event after this call.
1538 * Returns: %TRUE if the event was handled.
1543 gst_element_send_event (GstElement * element, GstEvent * event)
1545 GstElementClass *oclass;
1546 gboolean result = FALSE;
1548 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1549 g_return_val_if_fail (event != NULL, FALSE);
1551 oclass = GST_ELEMENT_GET_CLASS (element);
1553 GST_STATE_LOCK (element);
1554 if (oclass->send_event) {
1555 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1556 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1557 result = oclass->send_event (element, event);
1559 result = gst_element_default_send_event (element, event);
1561 GST_STATE_UNLOCK (element);
1568 * @element: a #GstElement to send the event to.
1569 * @rate: The new playback rate
1570 * @format: The format of the seek values
1571 * @flags: The optional seek flags.
1572 * @cur_type: The type and flags for the new current position
1573 * @cur: The value of the new current position
1574 * @stop_type: The type and flags for the new stop position
1575 * @stop: The value of the new stop position
1577 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1578 * the parameters. The seek event is sent to the element using
1579 * gst_element_send_event().
1581 * Returns: %TRUE if the event was handled.
1586 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1587 GstSeekFlags flags, GstSeekType cur_type, gint64 cur,
1588 GstSeekType stop_type, gint64 stop)
1593 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1596 gst_event_new_seek (rate, format, flags, cur_type, cur, stop_type, stop);
1597 result = gst_element_send_event (element, event);
1603 * gst_element_get_query_types:
1604 * @element: a #GstElement to query
1606 * Get an array of query types from the element.
1607 * If the element doesn't implement a query types function,
1608 * the query will be forwarded to the peer of a random linked sink pad.
1610 * Returns: An array of #GstQueryType elements that should not
1611 * be freed or modified.
1615 const GstQueryType *
1616 gst_element_get_query_types (GstElement * element)
1618 GstElementClass *oclass;
1619 const GstQueryType *result = NULL;
1621 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1623 oclass = GST_ELEMENT_GET_CLASS (element);
1625 if (oclass->get_query_types) {
1626 result = oclass->get_query_types (element);
1628 GstPad *pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1631 GstPad *peer = gst_pad_get_peer (pad);
1634 result = gst_pad_get_query_types (peer);
1636 gst_object_unref (peer);
1638 gst_object_unref (pad);
1645 gst_element_default_query (GstElement * element, GstQuery * query)
1647 gboolean result = FALSE;
1650 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1652 result = gst_pad_query (pad, query);
1654 gst_object_unref (pad);
1656 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1658 GstPad *peer = gst_pad_get_peer (pad);
1661 result = gst_pad_query (peer, query);
1663 gst_object_unref (peer);
1665 gst_object_unref (pad);
1672 * gst_element_query:
1673 * @element: a #GstElement to perform the query on.
1674 * @query: (transfer none): the #GstQuery.
1676 * Performs a query on the given element.
1678 * For elements that don't implement a query handler, this function
1679 * forwards the query to a random srcpad or to the peer of a
1680 * random linked sinkpad of this element.
1682 * Please note that some queries might need a running pipeline to work.
1684 * Returns: TRUE if the query could be performed.
1689 gst_element_query (GstElement * element, GstQuery * query)
1691 GstElementClass *oclass;
1692 gboolean result = FALSE;
1694 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1695 g_return_val_if_fail (query != NULL, FALSE);
1697 oclass = GST_ELEMENT_GET_CLASS (element);
1699 if (oclass->query) {
1700 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1701 GST_ELEMENT_NAME (element));
1702 result = oclass->query (element, query);
1704 result = gst_element_default_query (element, query);
1710 * gst_element_post_message:
1711 * @element: a #GstElement posting the message
1712 * @message: (transfer full): a #GstMessage to post
1714 * Post a message on the element's #GstBus. This function takes ownership of the
1715 * message; if you want to access the message after this call, you should add an
1716 * additional reference before calling.
1718 * Returns: %TRUE if the message was successfully posted. The function returns
1719 * %FALSE if the element did not have a bus.
1724 gst_element_post_message (GstElement * element, GstMessage * message)
1727 gboolean result = FALSE;
1729 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1730 g_return_val_if_fail (message != NULL, FALSE);
1732 GST_OBJECT_LOCK (element);
1735 if (G_UNLIKELY (bus == NULL))
1738 gst_object_ref (bus);
1739 GST_OBJECT_UNLOCK (element);
1741 /* we release the element lock when posting the message so that any
1742 * (synchronous) message handlers can operate on the element */
1743 result = gst_bus_post (bus, message);
1744 gst_object_unref (bus);
1751 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1752 "not posting message %p: no bus", message);
1753 GST_OBJECT_UNLOCK (element);
1754 gst_message_unref (message);
1760 * _gst_element_error_printf:
1761 * @format: the printf-like format to use, or %NULL
1763 * This function is only used internally by the gst_element_error() macro.
1765 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1771 _gst_element_error_printf (const gchar * format, ...)
1781 va_start (args, format);
1782 buffer = g_strdup_vprintf (format, args);
1788 * gst_element_message_full:
1789 * @element: a #GstElement to send message from
1790 * @type: the #GstMessageType
1791 * @domain: the GStreamer GError domain this message belongs to
1792 * @code: the GError code belonging to the domain
1793 * @text: (allow-none) (transfer full): an allocated text string to be used
1794 * as a replacement for the default message connected to code,
1796 * @debug: (allow-none) (transfer full): an allocated debug message to be
1797 * used as a replacement for the default debugging information,
1799 * @file: the source code file where the error was generated
1800 * @function: the source code function where the error was generated
1801 * @line: the source code line where the error was generated
1803 * Post an error, warning or info message on the bus from inside an element.
1805 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1806 * #GST_MESSAGE_INFO.
1810 void gst_element_message_full
1811 (GstElement * element, GstMessageType type,
1812 GQuark domain, gint code, gchar * text,
1813 gchar * debug, const gchar * file, const gchar * function, gint line)
1815 GError *gerror = NULL;
1819 gboolean has_debug = TRUE;
1820 GstMessage *message = NULL;
1823 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1824 g_return_if_fail (GST_IS_ELEMENT (element));
1825 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1826 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1828 /* check if we send the given text or the default error text */
1829 if ((text == NULL) || (text[0] == 0)) {
1830 /* text could have come from g_strdup_printf (""); */
1832 sent_text = gst_error_get_message (domain, code);
1836 /* construct a sent_debug with extra information from source */
1837 if ((debug == NULL) || (debug[0] == 0)) {
1838 /* debug could have come from g_strdup_printf (""); */
1842 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1844 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1845 file, line, function, name, debug);
1847 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1848 file, line, function, name);
1852 /* create gerror and post message */
1853 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1855 gerror = g_error_new_literal (domain, code, sent_text);
1858 case GST_MESSAGE_ERROR:
1860 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1862 case GST_MESSAGE_WARNING:
1863 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1866 case GST_MESSAGE_INFO:
1867 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1871 g_assert_not_reached ();
1874 gst_element_post_message (element, message);
1876 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1877 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1880 g_error_free (gerror);
1881 g_free (sent_debug);
1886 * gst_element_is_locked_state:
1887 * @element: a #GstElement.
1889 * Checks if the state of an element is locked.
1890 * If the state of an element is locked, state changes of the parent don't
1891 * affect the element.
1892 * This way you can leave currently unused elements inside bins. Just lock their
1893 * state before changing the state from #GST_STATE_NULL.
1897 * Returns: TRUE, if the element's state is locked.
1900 gst_element_is_locked_state (GstElement * element)
1904 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1906 GST_OBJECT_LOCK (element);
1907 result = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1908 GST_OBJECT_UNLOCK (element);
1914 * gst_element_set_locked_state:
1915 * @element: a #GstElement
1916 * @locked_state: TRUE to lock the element's state
1918 * Locks the state of an element, so state changes of the parent don't affect
1919 * this element anymore.
1923 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1924 * or the elements state-locking needed no change.
1927 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1931 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1933 GST_OBJECT_LOCK (element);
1934 old = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1936 if (G_UNLIKELY (old == locked_state))
1940 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1941 GST_ELEMENT_NAME (element));
1942 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_LOCKED_STATE);
1944 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1945 GST_ELEMENT_NAME (element));
1946 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_LOCKED_STATE);
1948 GST_OBJECT_UNLOCK (element);
1954 GST_CAT_DEBUG (GST_CAT_STATES,
1955 "elements %s was already in locked state %d",
1956 GST_ELEMENT_NAME (element), old);
1957 GST_OBJECT_UNLOCK (element);
1964 * gst_element_sync_state_with_parent:
1965 * @element: a #GstElement.
1967 * Tries to change the state of the element to the same as its parent.
1968 * If this function returns FALSE, the state of element is undefined.
1970 * Returns: TRUE, if the element's state could be synced to the parent's state.
1975 gst_element_sync_state_with_parent (GstElement * element)
1979 GstStateChangeReturn ret;
1981 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1983 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1984 GstState parent_current, parent_pending;
1986 GST_OBJECT_LOCK (parent);
1987 parent_current = GST_STATE (parent);
1988 parent_pending = GST_STATE_PENDING (parent);
1989 GST_OBJECT_UNLOCK (parent);
1991 /* set to pending if there is one, else we set it to the current state of
1993 if (parent_pending != GST_STATE_VOID_PENDING)
1994 target = parent_pending;
1996 target = parent_current;
1998 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1999 "syncing state (%s) to parent %s %s (%s, %s)",
2000 gst_element_state_get_name (GST_STATE (element)),
2001 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
2002 gst_element_state_get_name (parent_current),
2003 gst_element_state_get_name (parent_pending));
2005 ret = gst_element_set_state (element, target);
2006 if (ret == GST_STATE_CHANGE_FAILURE)
2009 gst_object_unref (parent);
2013 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
2020 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2021 "syncing state failed (%s)",
2022 gst_element_state_change_return_get_name (ret));
2023 gst_object_unref (parent);
2029 static GstStateChangeReturn
2030 gst_element_get_state_func (GstElement * element,
2031 GstState * state, GstState * pending, GstClockTime timeout)
2033 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2034 GstState old_pending;
2036 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2037 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2039 GST_OBJECT_LOCK (element);
2040 ret = GST_STATE_RETURN (element);
2041 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2042 gst_element_state_change_return_get_name (ret));
2044 /* we got an error, report immediately */
2045 if (ret == GST_STATE_CHANGE_FAILURE)
2048 /* we got no_preroll, report immediatly */
2049 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2052 /* no need to wait async if we are not async */
2053 if (ret != GST_STATE_CHANGE_ASYNC)
2056 old_pending = GST_STATE_PENDING (element);
2057 if (old_pending != GST_STATE_VOID_PENDING) {
2058 GTimeVal *timeval, abstimeout;
2061 if (timeout != GST_CLOCK_TIME_NONE) {
2062 glong add = timeout / 1000;
2067 /* make timeout absolute */
2068 g_get_current_time (&abstimeout);
2069 g_time_val_add (&abstimeout, add);
2070 timeval = &abstimeout;
2074 /* get cookie to detect state changes during waiting */
2075 cookie = element->state_cookie;
2077 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2078 "waiting for element to commit state");
2080 /* we have a pending state change, wait for it to complete */
2081 if (!GST_STATE_TIMED_WAIT (element, timeval)) {
2082 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2083 /* timeout triggered */
2084 ret = GST_STATE_CHANGE_ASYNC;
2086 if (cookie != element->state_cookie)
2089 /* could be success or failure */
2090 if (old_pending == GST_STATE (element)) {
2091 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2092 ret = GST_STATE_CHANGE_SUCCESS;
2094 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2095 ret = GST_STATE_CHANGE_FAILURE;
2098 /* if nothing is pending anymore we can return SUCCESS */
2099 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2100 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2101 ret = GST_STATE_CHANGE_SUCCESS;
2107 *state = GST_STATE (element);
2109 *pending = GST_STATE_PENDING (element);
2111 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2112 "state current: %s, pending: %s, result: %s",
2113 gst_element_state_get_name (GST_STATE (element)),
2114 gst_element_state_get_name (GST_STATE_PENDING (element)),
2115 gst_element_state_change_return_get_name (ret));
2116 GST_OBJECT_UNLOCK (element);
2123 *state = GST_STATE_VOID_PENDING;
2125 *pending = GST_STATE_VOID_PENDING;
2127 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2129 GST_OBJECT_UNLOCK (element);
2131 return GST_STATE_CHANGE_FAILURE;
2136 * gst_element_get_state:
2137 * @element: a #GstElement to get the state of.
2138 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2140 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2141 * state. Can be %NULL.
2142 * @timeout: a #GstClockTime to specify the timeout for an async
2143 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2145 * Gets the state of the element.
2147 * For elements that performed an ASYNC state change, as reported by
2148 * gst_element_set_state(), this function will block up to the
2149 * specified timeout value for the state change to complete.
2150 * If the element completes the state change or goes into
2151 * an error, this function returns immediately with a return value of
2152 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2154 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2155 * returns the current and pending state immediately.
2157 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2158 * successfully changed its state but is not able to provide data yet.
2159 * This mostly happens for live sources that only produce data in
2160 * %GST_STATE_PLAYING. While the state change return is equivalent to
2161 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2162 * some sink elements might not be able to complete their state change because
2163 * an element is not producing data to complete the preroll. When setting the
2164 * element to playing, the preroll will complete and playback will start.
2166 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2167 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2168 * element is still performing a state change or
2169 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2173 GstStateChangeReturn
2174 gst_element_get_state (GstElement * element,
2175 GstState * state, GstState * pending, GstClockTime timeout)
2177 GstElementClass *oclass;
2178 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2180 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2182 oclass = GST_ELEMENT_GET_CLASS (element);
2184 if (oclass->get_state)
2185 result = (oclass->get_state) (element, state, pending, timeout);
2191 * gst_element_abort_state:
2192 * @element: a #GstElement to abort the state of.
2194 * Abort the state change of the element. This function is used
2195 * by elements that do asynchronous state changes and find out
2196 * something is wrong.
2198 * This function should be called with the STATE_LOCK held.
2203 gst_element_abort_state (GstElement * element)
2207 #ifndef GST_DISABLE_GST_DEBUG
2211 g_return_if_fail (GST_IS_ELEMENT (element));
2213 GST_OBJECT_LOCK (element);
2214 pending = GST_STATE_PENDING (element);
2216 if (pending == GST_STATE_VOID_PENDING ||
2217 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2218 goto nothing_aborted;
2220 #ifndef GST_DISABLE_GST_DEBUG
2221 old_state = GST_STATE (element);
2223 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2224 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2225 gst_element_state_get_name (pending));
2229 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2231 GST_STATE_BROADCAST (element);
2232 GST_OBJECT_UNLOCK (element);
2238 GST_OBJECT_UNLOCK (element);
2244 * gst_element_continue_state:
2245 * @element: a #GstElement to continue the state change of.
2246 * @ret: The previous state return value
2248 * Commit the state change of the element and proceed to the next
2249 * pending state if any. This function is used
2250 * by elements that do asynchronous state changes.
2251 * The core will normally call this method automatically when an
2252 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2254 * If after calling this method the element still has not reached
2255 * the pending state, the next state change is performed.
2257 * This method is used internally and should normally not be called by plugins
2260 * Returns: The result of the commit state change.
2264 GstStateChangeReturn
2265 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2267 GstStateChangeReturn old_ret;
2268 GstState old_state, old_next;
2269 GstState current, next, pending;
2270 GstMessage *message;
2271 GstStateChange transition;
2273 GST_OBJECT_LOCK (element);
2274 old_ret = GST_STATE_RETURN (element);
2275 GST_STATE_RETURN (element) = ret;
2276 pending = GST_STATE_PENDING (element);
2278 /* check if there is something to commit */
2279 if (pending == GST_STATE_VOID_PENDING)
2280 goto nothing_pending;
2282 old_state = GST_STATE (element);
2283 /* this is the state we should go to next */
2284 old_next = GST_STATE_NEXT (element);
2285 /* update current state */
2286 current = GST_STATE (element) = old_next;
2288 /* see if we reached the final state */
2289 if (pending == current)
2292 next = GST_STATE_GET_NEXT (current, pending);
2293 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2295 GST_STATE_NEXT (element) = next;
2297 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2298 GST_OBJECT_UNLOCK (element);
2300 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2301 "committing state from %s to %s, pending %s, next %s",
2302 gst_element_state_get_name (old_state),
2303 gst_element_state_get_name (old_next),
2304 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2306 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2307 old_state, old_next, pending);
2308 gst_element_post_message (element, message);
2310 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2311 "continue state change %s to %s, final %s",
2312 gst_element_state_get_name (current),
2313 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2315 ret = gst_element_change_state (element, transition);
2321 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2322 GST_OBJECT_UNLOCK (element);
2327 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2328 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2330 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2331 "completed state change to %s", gst_element_state_get_name (pending));
2332 GST_OBJECT_UNLOCK (element);
2334 /* don't post silly messages with the same state. This can happen
2335 * when an element state is changed to what it already was. For bins
2336 * this can be the result of a lost state, which we check with the
2337 * previous return value.
2338 * We do signal the cond though as a _get_state() might be blocking
2340 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC) {
2341 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2342 "posting state-changed %s to %s",
2343 gst_element_state_get_name (old_state),
2344 gst_element_state_get_name (old_next));
2346 gst_message_new_state_changed (GST_OBJECT_CAST (element), old_state,
2347 old_next, GST_STATE_VOID_PENDING);
2348 gst_element_post_message (element, message);
2351 GST_STATE_BROADCAST (element);
2358 * gst_element_lost_state_full:
2359 * @element: a #GstElement the state is lost of
2360 * @new_base_time: if a new base time should be distributed
2362 * Brings the element to the lost state. The current state of the
2363 * element is copied to the pending state so that any call to
2364 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2366 * An ASYNC_START message is posted with indication to distribute a new
2367 * base_time to the element when @new_base_time is %TRUE.
2368 * If the element was PLAYING, it will go to PAUSED. The element
2369 * will be restored to its PLAYING state by the parent pipeline when it
2372 * This is mostly used for elements that lost their preroll buffer
2373 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2374 * they will go to their pending state again when a new preroll buffer is
2375 * queued. This function can only be called when the element is currently
2376 * not in error or an async state change.
2378 * This function is used internally and should normally not be called from
2379 * plugins or applications.
2386 gst_element_lost_state_full (GstElement * element, gboolean new_base_time)
2388 GstState old_state, new_state;
2389 GstMessage *message;
2391 g_return_if_fail (GST_IS_ELEMENT (element));
2393 GST_OBJECT_LOCK (element);
2394 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2397 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2398 goto only_async_start;
2400 old_state = GST_STATE (element);
2402 /* when we were PLAYING, the new state is PAUSED. We will also not
2403 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2404 * when we preroll. */
2405 if (old_state > GST_STATE_PAUSED)
2406 new_state = GST_STATE_PAUSED;
2408 new_state = old_state;
2410 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2411 "lost state of %s to %s", gst_element_state_get_name (old_state),
2412 gst_element_state_get_name (new_state));
2414 GST_STATE (element) = new_state;
2415 GST_STATE_NEXT (element) = new_state;
2416 GST_STATE_PENDING (element) = new_state;
2417 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2419 GST_ELEMENT_START_TIME (element) = 0;
2420 GST_OBJECT_UNLOCK (element);
2422 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2423 new_state, new_state, new_state);
2424 gst_element_post_message (element, message);
2427 gst_message_new_async_start (GST_OBJECT_CAST (element), new_base_time);
2428 gst_element_post_message (element, message);
2434 GST_OBJECT_UNLOCK (element);
2439 GST_OBJECT_UNLOCK (element);
2441 message = gst_message_new_async_start (GST_OBJECT_CAST (element), TRUE);
2442 gst_element_post_message (element, message);
2448 * gst_element_lost_state:
2449 * @element: a #GstElement the state is lost of
2451 * Brings the element to the lost state. This function calls
2452 * gst_element_lost_state_full() with the new_base_time set to %TRUE.
2454 * This function is used internally and should normally not be called from
2455 * plugins or applications.
2460 gst_element_lost_state (GstElement * element)
2462 gst_element_lost_state_full (element, TRUE);
2466 * gst_element_set_state:
2467 * @element: a #GstElement to change state of.
2468 * @state: the element's new #GstState.
2470 * Sets the state of the element. This function will try to set the
2471 * requested state by going through all the intermediary states and calling
2472 * the class's state change function for each.
2474 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2475 * element will perform the remainder of the state change asynchronously in
2477 * An application can use gst_element_get_state() to wait for the completion
2478 * of the state change or it can wait for a state change message on the bus.
2480 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2481 * #GST_STATE_CHANGE_ASYNC.
2483 * Returns: Result of the state change using #GstStateChangeReturn.
2487 GstStateChangeReturn
2488 gst_element_set_state (GstElement * element, GstState state)
2490 GstElementClass *oclass;
2491 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2493 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2495 oclass = GST_ELEMENT_GET_CLASS (element);
2497 if (oclass->set_state)
2498 result = (oclass->set_state) (element, state);
2504 * default set state function, calculates the next state based
2505 * on current state and calls the change_state function
2507 static GstStateChangeReturn
2508 gst_element_set_state_func (GstElement * element, GstState state)
2510 GstState current, next, old_pending;
2511 GstStateChangeReturn ret;
2512 GstStateChange transition;
2513 GstStateChangeReturn old_ret;
2515 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2517 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2518 gst_element_state_get_name (state));
2520 /* state lock is taken to protect the set_state() and get_state()
2521 * procedures, it does not lock any variables. */
2522 GST_STATE_LOCK (element);
2524 /* now calculate how to get to the new state */
2525 GST_OBJECT_LOCK (element);
2526 old_ret = GST_STATE_RETURN (element);
2527 /* previous state change returned an error, remove all pending
2528 * and next states */
2529 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2530 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2531 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2532 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2535 current = GST_STATE (element);
2536 next = GST_STATE_NEXT (element);
2537 old_pending = GST_STATE_PENDING (element);
2539 /* this is the (new) state we should go to. TARGET is the last state we set on
2541 if (state != GST_STATE_TARGET (element)) {
2542 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2543 "setting target state to %s", gst_element_state_get_name (state));
2544 GST_STATE_TARGET (element) = state;
2545 /* increment state cookie so that we can track each state change. We only do
2546 * this if this is actually a new state change. */
2547 element->state_cookie++;
2549 GST_STATE_PENDING (element) = state;
2551 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2552 "current %s, old_pending %s, next %s, old return %s",
2553 gst_element_state_get_name (current),
2554 gst_element_state_get_name (old_pending),
2555 gst_element_state_get_name (next),
2556 gst_element_state_change_return_get_name (old_ret));
2558 /* if the element was busy doing a state change, we just update the
2559 * target state, it'll get to it async then. */
2560 if (old_pending != GST_STATE_VOID_PENDING) {
2561 /* upwards state change will happen ASYNC */
2562 if (old_pending <= state)
2564 /* element is going to this state already */
2565 else if (next == state)
2567 /* element was performing an ASYNC upward state change and
2568 * we request to go downward again. Start from the next pending
2570 else if (next > state
2571 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2575 next = GST_STATE_GET_NEXT (current, state);
2576 /* now we store the next state */
2577 GST_STATE_NEXT (element) = next;
2578 /* mark busy, we need to check that there is actually a state change
2579 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2580 * the default element change_state function has no way to know what the
2581 * old value was... could consider this a FIXME...*/
2582 if (current != next)
2583 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2585 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2587 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2588 "%s: setting state from %s to %s",
2589 (next != state ? "intermediate" : "final"),
2590 gst_element_state_get_name (current), gst_element_state_get_name (next));
2592 /* now signal any waiters, they will error since the cookie was incremented */
2593 GST_STATE_BROADCAST (element);
2595 GST_OBJECT_UNLOCK (element);
2597 ret = gst_element_change_state (element, transition);
2599 GST_STATE_UNLOCK (element);
2601 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2602 gst_element_state_change_return_get_name (ret));
2608 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2609 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2610 "element was busy with async state change");
2611 GST_OBJECT_UNLOCK (element);
2613 GST_STATE_UNLOCK (element);
2615 return GST_STATE_CHANGE_ASYNC;
2620 * gst_element_change_state:
2621 * @element: a #GstElement
2622 * @transition: the requested transition
2624 * Perform @transition on @element.
2626 * This function must be called with STATE_LOCK held and is mainly used
2629 * Returns: the #GstStateChangeReturn of the state transition.
2631 GstStateChangeReturn
2632 gst_element_change_state (GstElement * element, GstStateChange transition)
2634 GstElementClass *oclass;
2635 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2637 oclass = GST_ELEMENT_GET_CLASS (element);
2639 /* call the state change function so it can set the state */
2640 if (oclass->change_state)
2641 ret = (oclass->change_state) (element, transition);
2643 ret = GST_STATE_CHANGE_FAILURE;
2646 case GST_STATE_CHANGE_FAILURE:
2647 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2648 "have FAILURE change_state return");
2649 /* state change failure */
2650 gst_element_abort_state (element);
2652 case GST_STATE_CHANGE_ASYNC:
2656 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2657 "element will change state ASYNC");
2659 target = GST_STATE_TARGET (element);
2661 if (target > GST_STATE_READY)
2664 /* else we just continue the state change downwards */
2665 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2666 "forcing commit state %s <= %s",
2667 gst_element_state_get_name (target),
2668 gst_element_state_get_name (GST_STATE_READY));
2670 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2673 case GST_STATE_CHANGE_SUCCESS:
2674 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2675 "element changed state SUCCESS");
2676 /* we can commit the state now which will proceeed to
2678 ret = gst_element_continue_state (element, ret);
2680 case GST_STATE_CHANGE_NO_PREROLL:
2681 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2682 "element changed state NO_PREROLL");
2683 /* we can commit the state now which will proceeed to
2685 ret = gst_element_continue_state (element, ret);
2688 goto invalid_return;
2691 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2696 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2704 GST_OBJECT_LOCK (element);
2705 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2706 g_critical ("%s: unknown return value %d from a state change function",
2707 GST_ELEMENT_NAME (element), ret);
2709 /* we are in error now */
2710 ret = GST_STATE_CHANGE_FAILURE;
2711 GST_STATE_RETURN (element) = ret;
2712 GST_OBJECT_UNLOCK (element);
2718 /* gst_iterator_fold functions for pads_activate
2719 * Note how we don't stop the iterator when we fail an activation. This is
2720 * probably a FIXME since when one pad activation fails, we don't want to
2721 * continue our state change. */
2723 activate_pads (GstPad * pad, GValue * ret, gboolean * active)
2725 if (!gst_pad_set_active (pad, *active))
2726 g_value_set_boolean (ret, FALSE);
2728 /* unref the object that was reffed for us by _fold */
2729 gst_object_unref (pad);
2733 /* set the caps on the pad to NULL */
2735 clear_caps (GstPad * pad, GValue * ret, gboolean * active)
2737 gst_pad_set_caps (pad, NULL);
2738 gst_object_unref (pad);
2742 /* returns false on error or early cutout (will never happen because the fold
2743 * function always returns TRUE, see FIXME above) of the fold, true if all
2744 * pads in @iter were (de)activated successfully. */
2746 iterator_activate_fold_with_resync (GstIterator * iter,
2747 GstIteratorFoldFunction func, gpointer user_data)
2749 GstIteratorResult ires;
2752 /* no need to unset this later, it's just a boolean */
2753 g_value_init (&ret, G_TYPE_BOOLEAN);
2754 g_value_set_boolean (&ret, TRUE);
2757 ires = gst_iterator_fold (iter, func, &ret, user_data);
2759 case GST_ITERATOR_RESYNC:
2760 /* need to reset the result again */
2761 g_value_set_boolean (&ret, TRUE);
2762 gst_iterator_resync (iter);
2764 case GST_ITERATOR_DONE:
2765 /* all pads iterated, return collected value */
2768 /* iterator returned _ERROR or premature end with _OK,
2769 * mark an error and exit */
2770 g_value_set_boolean (&ret, FALSE);
2775 /* return collected value */
2776 return g_value_get_boolean (&ret);
2779 /* is called with STATE_LOCK
2781 * Pads are activated from source pads to sinkpads.
2784 gst_element_pads_activate (GstElement * element, gboolean active)
2789 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2790 "pads_activate with active %d", active);
2792 iter = gst_element_iterate_src_pads (element);
2794 iterator_activate_fold_with_resync (iter,
2795 (GstIteratorFoldFunction) activate_pads, &active);
2796 gst_iterator_free (iter);
2797 if (G_UNLIKELY (!res))
2800 iter = gst_element_iterate_sink_pads (element);
2802 iterator_activate_fold_with_resync (iter,
2803 (GstIteratorFoldFunction) activate_pads, &active);
2804 gst_iterator_free (iter);
2805 if (G_UNLIKELY (!res))
2809 /* clear the caps on all pads, this should never fail */
2810 iter = gst_element_iterate_pads (element);
2812 iterator_activate_fold_with_resync (iter,
2813 (GstIteratorFoldFunction) clear_caps, &active);
2814 gst_iterator_free (iter);
2815 if (G_UNLIKELY (!res))
2819 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2820 "pads_activate successful");
2827 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2828 "source pads_activate failed");
2833 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2834 "sink pads_activate failed");
2839 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2840 "failed to clear caps on pads");
2845 /* is called with STATE_LOCK */
2846 static GstStateChangeReturn
2847 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2849 GstState state, next;
2850 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2853 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2855 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2856 next = GST_STATE_TRANSITION_NEXT (transition);
2858 /* if the element already is in the given state, we just return success */
2859 if (next == GST_STATE_VOID_PENDING || state == next)
2862 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2863 "default handler tries setting state from %s to %s (%04x)",
2864 gst_element_state_get_name (state),
2865 gst_element_state_get_name (next), transition);
2867 switch (transition) {
2868 case GST_STATE_CHANGE_NULL_TO_READY:
2870 case GST_STATE_CHANGE_READY_TO_PAUSED:
2871 if (!gst_element_pads_activate (element, TRUE)) {
2872 result = GST_STATE_CHANGE_FAILURE;
2875 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2877 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2879 case GST_STATE_CHANGE_PAUSED_TO_READY:
2880 case GST_STATE_CHANGE_READY_TO_NULL:
2881 /* deactivate pads in both cases, since they are activated on
2882 ready->paused but the element might not have made it to paused */
2883 if (!gst_element_pads_activate (element, FALSE)) {
2884 result = GST_STATE_CHANGE_FAILURE;
2886 gst_element_set_base_time (element, 0);
2889 /* In null state release the reference to the clock */
2890 GST_OBJECT_LOCK (element);
2891 clock_p = &element->clock;
2892 gst_object_replace ((GstObject **) clock_p, NULL);
2893 GST_OBJECT_UNLOCK (element);
2896 /* this will catch real but unhandled state changes;
2897 * can only be caused by:
2898 * - a new state was added
2899 * - somehow the element was asked to jump across an intermediate state
2901 g_warning ("Unhandled state change from %s to %s",
2902 gst_element_state_get_name (state),
2903 gst_element_state_get_name (next));
2910 GST_OBJECT_LOCK (element);
2911 result = GST_STATE_RETURN (element);
2912 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2913 "element is already in the %s state",
2914 gst_element_state_get_name (state));
2915 GST_OBJECT_UNLOCK (element);
2922 * gst_element_get_factory:
2923 * @element: a #GstElement to request the element factory of.
2925 * Retrieves the factory that was used to create this element.
2927 * Returns: (transfer none): the #GstElementFactory used for creating this
2928 * element. no refcounting is needed.
2931 gst_element_get_factory (GstElement * element)
2933 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2935 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2939 gst_element_dispose (GObject * object)
2941 GstElement *element = GST_ELEMENT_CAST (object);
2945 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2947 if (GST_STATE (element) != GST_STATE_NULL)
2950 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2951 "removing %d pads", g_list_length (element->pads));
2952 /* first we break all our links with the outside */
2953 while (element->pads && element->pads->data) {
2954 /* don't call _remove_pad with NULL */
2955 gst_element_remove_pad (element, GST_PAD_CAST (element->pads->data));
2957 if (G_UNLIKELY (element->pads != NULL)) {
2958 g_critical ("could not remove pads from element %s",
2959 GST_STR_NULL (GST_OBJECT_NAME (object)));
2962 GST_OBJECT_LOCK (element);
2963 clock_p = &element->clock;
2964 bus_p = &element->bus;
2965 gst_object_replace ((GstObject **) clock_p, NULL);
2966 gst_object_replace ((GstObject **) bus_p, NULL);
2967 GST_OBJECT_UNLOCK (element);
2969 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2971 G_OBJECT_CLASS (parent_class)->dispose (object);
2980 is_locked = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
2982 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2984 "You need to explicitly set elements to the NULL state before\n"
2985 "dropping the final reference, to allow them to clean up.\n"
2986 "This problem may also be caused by a refcounting bug in the\n"
2987 "application or some element.\n",
2988 GST_OBJECT_NAME (element),
2989 gst_element_state_get_name (GST_STATE (element)),
2990 is_locked ? " (locked)" : "");
2996 gst_element_finalize (GObject * object)
2998 GstElement *element = GST_ELEMENT_CAST (object);
3000 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
3002 GST_STATE_LOCK (element);
3003 if (element->state_cond)
3004 g_cond_free (element->state_cond);
3005 element->state_cond = NULL;
3006 GST_STATE_UNLOCK (element);
3007 g_static_rec_mutex_free (element->state_lock);
3008 g_slice_free (GStaticRecMutex, element->state_lock);
3009 element->state_lock = NULL;
3011 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
3013 G_OBJECT_CLASS (parent_class)->finalize (object);
3017 gst_element_set_bus_func (GstElement * element, GstBus * bus)
3021 g_return_if_fail (GST_IS_ELEMENT (element));
3023 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
3025 GST_OBJECT_LOCK (element);
3026 bus_p = &GST_ELEMENT_BUS (element);
3027 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
3028 GST_OBJECT_UNLOCK (element);
3032 * gst_element_set_bus:
3033 * @element: a #GstElement to set the bus of.
3034 * @bus: (transfer none): the #GstBus to set.
3036 * Sets the bus of the element. Increases the refcount on the bus.
3037 * For internal use only, unless you're testing elements.
3042 gst_element_set_bus (GstElement * element, GstBus * bus)
3044 GstElementClass *oclass;
3046 g_return_if_fail (GST_IS_ELEMENT (element));
3048 oclass = GST_ELEMENT_GET_CLASS (element);
3050 if (oclass->set_bus)
3051 oclass->set_bus (element, bus);
3055 * gst_element_get_bus:
3056 * @element: a #GstElement to get the bus of.
3058 * Returns the bus of the element. Note that only a #GstPipeline will provide a
3059 * bus for the application.
3061 * Returns: (transfer full): the element's #GstBus. unref after usage.
3066 gst_element_get_bus (GstElement * element)
3068 GstBus *result = NULL;
3070 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3072 GST_OBJECT_LOCK (element);
3073 if ((result = GST_ELEMENT_BUS (element)))
3074 gst_object_ref (result);
3075 GST_OBJECT_UNLOCK (element);
3077 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,