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 * An existing pad of an element can be retrieved by name with
45 * gst_element_get_static_pad(). A new dynamic pad can be created using
46 * gst_element_request_pad() with a #GstPadTemplate or
47 * gst_element_get_request_pad() with the template name such as "src_\%d".
48 * An iterator of all pads can be retrieved with gst_element_iterate_pads().
50 * Elements can be linked through their pads.
51 * If the link is straightforward, use the gst_element_link()
52 * convenience function to link two elements, or gst_element_link_many()
53 * for more elements in a row.
54 * Use gst_element_link_filtered() to link two elements constrained by
55 * a specified set of #GstCaps.
56 * For finer control, use gst_element_link_pads() and
57 * gst_element_link_pads_filtered() to specify the pads to link on
58 * each element by name.
60 * Each element has a state (see #GstState). You can get and set the state
61 * of an element with gst_element_get_state() and gst_element_set_state().
62 * Setting a state triggers a #GstStateChange. To get a string representation
63 * of a #GstState, use gst_element_state_get_name().
65 * You can get and set a #GstClock on an element using gst_element_get_clock()
66 * and gst_element_set_clock().
67 * Some elements can provide a clock for the pipeline if
68 * gst_element_provides_clock() returns %TRUE. With the
69 * gst_element_provide_clock() method one can retrieve the clock provided by
71 * Not all elements require a clock to operate correctly. If
72 * gst_element_requires_clock() returns %TRUE, a clock should be set on the
73 * element with gst_element_set_clock().
75 * Note that clock slection and distribution is normally handled by the
76 * toplevel #GstPipeline so the clock functions are only to be used in very
77 * specific situations.
79 * Last reviewed on 2009-05-29 (0.10.24)
82 #include "gst_private.h"
85 #include <gobject/gvaluecollector.h>
87 #include "gstelement.h"
88 #include "gstelementmetadata.h"
89 #include "gstenumtypes.h"
91 #include "gstmarshal.h"
97 #include "gst-i18n-lib.h"
99 /* Element signals and args */
115 static void gst_element_class_init (GstElementClass * klass);
116 static void gst_element_init (GstElement * element);
117 static void gst_element_base_class_init (gpointer g_class);
118 static void gst_element_base_class_finalize (gpointer g_class);
120 static void gst_element_dispose (GObject * object);
121 static void gst_element_finalize (GObject * object);
123 static GstStateChangeReturn gst_element_change_state_func (GstElement * element,
124 GstStateChange transition);
125 static GstStateChangeReturn gst_element_get_state_func (GstElement * element,
126 GstState * state, GstState * pending, GstClockTime timeout);
127 static GstStateChangeReturn gst_element_set_state_func (GstElement * element,
129 static void gst_element_set_bus_func (GstElement * element, GstBus * bus);
131 static gboolean gst_element_default_send_event (GstElement * element,
133 static gboolean gst_element_default_query (GstElement * element,
136 static GstPadTemplate
137 * gst_element_class_get_request_pad_template (GstElementClass *
138 element_class, const gchar * name);
140 static GstObjectClass *parent_class = NULL;
141 static guint gst_element_signals[LAST_SIGNAL] = { 0 };
143 /* this is used in gstelementfactory.c:gst_element_register() */
144 GQuark __gst_elementclass_factory = 0;
147 gst_element_get_type (void)
149 static volatile gsize gst_element_type = 0;
151 if (g_once_init_enter (&gst_element_type)) {
153 static const GTypeInfo element_info = {
154 sizeof (GstElementClass),
155 gst_element_base_class_init,
156 gst_element_base_class_finalize,
157 (GClassInitFunc) gst_element_class_init,
162 (GInstanceInitFunc) gst_element_init,
166 _type = g_type_register_static (GST_TYPE_OBJECT, "GstElement",
167 &element_info, G_TYPE_FLAG_ABSTRACT);
169 __gst_elementclass_factory =
170 g_quark_from_static_string ("GST_ELEMENTCLASS_FACTORY");
171 g_once_init_leave (&gst_element_type, _type);
173 return gst_element_type;
177 gst_element_class_init (GstElementClass * klass)
179 GObjectClass *gobject_class;
181 gobject_class = (GObjectClass *) klass;
183 parent_class = g_type_class_peek_parent (klass);
186 * GstElement::pad-added:
187 * @gstelement: the object which received the signal
188 * @new_pad: the pad that has been added
190 * a new #GstPad has been added to the element. Note that this signal will
191 * usually be emitted from the context of the streaming thread. Also keep in
192 * mind that if you add new elements to the pipeline in the signal handler
193 * you will need to set them to the desired target state with
194 * gst_element_set_state() or gst_element_sync_state_with_parent().
196 gst_element_signals[PAD_ADDED] =
197 g_signal_new ("pad-added", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
198 G_STRUCT_OFFSET (GstElementClass, pad_added), NULL, NULL,
199 gst_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GST_TYPE_PAD);
201 * GstElement::pad-removed:
202 * @gstelement: the object which received the signal
203 * @old_pad: the pad that has been removed
205 * a #GstPad has been removed from the element
207 gst_element_signals[PAD_REMOVED] =
208 g_signal_new ("pad-removed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
209 G_STRUCT_OFFSET (GstElementClass, pad_removed), NULL, NULL,
210 gst_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GST_TYPE_PAD);
212 * GstElement::no-more-pads:
213 * @gstelement: the object which received the signal
215 * This signals that the element will not generate more dynamic pads.
216 * Note that this signal will usually be emitted from the context of
217 * the streaming thread.
219 gst_element_signals[NO_MORE_PADS] =
220 g_signal_new ("no-more-pads", G_TYPE_FROM_CLASS (klass),
221 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstElementClass, no_more_pads), NULL,
222 NULL, gst_marshal_VOID__VOID, G_TYPE_NONE, 0);
224 gobject_class->dispose = gst_element_dispose;
225 gobject_class->finalize = gst_element_finalize;
227 klass->change_state = GST_DEBUG_FUNCPTR (gst_element_change_state_func);
228 klass->set_state = GST_DEBUG_FUNCPTR (gst_element_set_state_func);
229 klass->get_state = GST_DEBUG_FUNCPTR (gst_element_get_state_func);
230 klass->set_bus = GST_DEBUG_FUNCPTR (gst_element_set_bus_func);
231 klass->query = GST_DEBUG_FUNCPTR (gst_element_default_query);
232 klass->send_event = GST_DEBUG_FUNCPTR (gst_element_default_send_event);
233 klass->numpadtemplates = 0;
235 klass->elementfactory = NULL;
239 gst_element_base_class_init (gpointer g_class)
241 GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
242 GList *node, *padtemplates;
244 /* Copy the element details here so elements can inherit the
245 * details from their base class and classes only need to set
246 * the details in class_init instead of base_init */
247 element_class->metadata =
248 element_class->metadata ? gst_structure_copy (element_class->metadata) :
249 gst_structure_empty_new ("metadata");
251 /* Copy the pad templates so elements inherit them
252 * from their base class but elements can add pad templates in class_init
253 * instead of base_init.
255 padtemplates = g_list_copy (element_class->padtemplates);
256 for (node = padtemplates; node != NULL; node = node->next) {
257 GstPadTemplate *tmpl = (GstPadTemplate *) node->data;
258 gst_object_ref (tmpl);
260 element_class->padtemplates = padtemplates;
262 /* set the factory, see gst_element_register() */
263 element_class->elementfactory =
264 g_type_get_qdata (G_TYPE_FROM_CLASS (element_class),
265 __gst_elementclass_factory);
266 GST_DEBUG ("type %s : factory %p", G_OBJECT_CLASS_NAME (element_class),
267 element_class->elementfactory);
271 gst_element_base_class_finalize (gpointer g_class)
273 GstElementClass *klass = GST_ELEMENT_CLASS (g_class);
275 g_list_foreach (klass->padtemplates, (GFunc) gst_object_unref, NULL);
276 g_list_free (klass->padtemplates);
278 gst_structure_free (klass->metadata);
282 gst_element_init (GstElement * element)
284 GST_STATE (element) = GST_STATE_NULL;
285 GST_STATE_TARGET (element) = GST_STATE_NULL;
286 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
287 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
288 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
290 g_static_rec_mutex_init (&element->state_lock);
291 element->state_cond = g_cond_new ();
295 * gst_element_release_request_pad:
296 * @element: a #GstElement to release the request pad of.
297 * @pad: the #GstPad to release.
299 * Makes the element free the previously requested pad as obtained
300 * with gst_element_get_request_pad().
302 * This does not unref the pad. If the pad was created by using
303 * gst_element_get_request_pad(), gst_element_release_request_pad() needs to be
304 * followed by gst_object_unref() to free the @pad.
309 gst_element_release_request_pad (GstElement * element, GstPad * pad)
311 GstElementClass *oclass;
313 g_return_if_fail (GST_IS_ELEMENT (element));
314 g_return_if_fail (GST_IS_PAD (pad));
316 oclass = GST_ELEMENT_GET_CLASS (element);
318 /* if the element implements a custom release function we call that, else we
319 * simply remove the pad from the element */
320 if (oclass->release_pad)
321 (oclass->release_pad) (element, pad);
323 gst_element_remove_pad (element, pad);
327 * gst_element_requires_clock:
328 * @element: a #GstElement to query
330 * Query if the element requires a clock.
332 * Returns: %TRUE if the element requires a clock
337 gst_element_requires_clock (GstElement * element)
341 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
343 result = (GST_ELEMENT_GET_CLASS (element)->set_clock != NULL);
349 * gst_element_provides_clock:
350 * @element: a #GstElement to query
352 * Query if the element provides a clock. A #GstClock provided by an
353 * element can be used as the global #GstClock for the pipeline.
354 * An element that can provide a clock is only required to do so in the PAUSED
355 * state, this means when it is fully negotiated and has allocated the resources
356 * to operate the clock.
358 * Returns: %TRUE if the element provides a clock
363 gst_element_provides_clock (GstElement * element)
367 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
369 result = (GST_ELEMENT_GET_CLASS (element)->provide_clock != NULL);
375 * gst_element_provide_clock:
376 * @element: a #GstElement to query
378 * Get the clock provided by the given element.
379 * <note>An element is only required to provide a clock in the PAUSED
380 * state. Some elements can provide a clock in other states.</note>
382 * Returns: (transfer full): the GstClock provided by the element or %NULL
383 * if no clock could be provided. Unref after usage.
388 gst_element_provide_clock (GstElement * element)
390 GstClock *result = NULL;
391 GstElementClass *oclass;
393 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
395 oclass = GST_ELEMENT_GET_CLASS (element);
397 if (oclass->provide_clock)
398 result = oclass->provide_clock (element);
404 * gst_element_set_clock:
405 * @element: a #GstElement to set the clock for.
406 * @clock: the #GstClock to set for the element.
408 * Sets the clock for the element. This function increases the
409 * refcount on the clock. Any previously set clock on the object
412 * Returns: %TRUE if the element accepted the clock. An element can refuse a
413 * clock when it, for example, is not able to slave its internal clock to the
414 * @clock or when it requires a specific clock to operate.
419 gst_element_set_clock (GstElement * element, GstClock * clock)
421 GstElementClass *oclass;
425 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
426 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
428 oclass = GST_ELEMENT_GET_CLASS (element);
430 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
432 if (oclass->set_clock)
433 res = oclass->set_clock (element, clock);
436 /* only update the clock pointer if the element accepted the clock */
437 GST_OBJECT_LOCK (element);
438 clock_p = &element->clock;
439 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
440 GST_OBJECT_UNLOCK (element);
446 * gst_element_get_clock:
447 * @element: a #GstElement to get the clock of.
449 * Gets the currently configured clock of the element. This is the clock as was
450 * last set with gst_element_set_clock().
452 * Returns: (transfer full): the #GstClock of the element. unref after usage.
457 gst_element_get_clock (GstElement * element)
461 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
463 GST_OBJECT_LOCK (element);
464 if ((result = element->clock))
465 gst_object_ref (result);
466 GST_OBJECT_UNLOCK (element);
472 * gst_element_set_base_time:
473 * @element: a #GstElement.
474 * @time: the base time to set.
476 * Set the base time of an element. See gst_element_get_base_time().
481 gst_element_set_base_time (GstElement * element, GstClockTime time)
485 g_return_if_fail (GST_IS_ELEMENT (element));
487 GST_OBJECT_LOCK (element);
488 old = element->base_time;
489 element->base_time = time;
490 GST_OBJECT_UNLOCK (element);
492 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
493 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
494 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
498 * gst_element_get_base_time:
499 * @element: a #GstElement.
501 * Returns the base time of the element. The base time is the
502 * absolute time of the clock when this element was last put to
503 * PLAYING. Subtracting the base time from the clock time gives
504 * the running time of the element.
506 * Returns: the base time of the element.
511 gst_element_get_base_time (GstElement * element)
515 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
517 GST_OBJECT_LOCK (element);
518 result = element->base_time;
519 GST_OBJECT_UNLOCK (element);
525 * gst_element_set_start_time:
526 * @element: a #GstElement.
527 * @time: the base time to set.
529 * Set the start time of an element. The start time of the element is the
530 * running time of the element when it last went to the PAUSED state. In READY
531 * or after a flushing seek, it is set to 0.
533 * Toplevel elements like #GstPipeline will manage the start_time and
534 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
535 * on such a toplevel element will disable the distribution of the base_time to
536 * the children and can be useful if the application manages the base_time
537 * itself, for example if you want to synchronize capture from multiple
538 * pipelines, and you can also ensure that the pipelines have the same clock.
545 gst_element_set_start_time (GstElement * element, GstClockTime time)
549 g_return_if_fail (GST_IS_ELEMENT (element));
551 GST_OBJECT_LOCK (element);
552 old = GST_ELEMENT_START_TIME (element);
553 GST_ELEMENT_START_TIME (element) = time;
554 GST_OBJECT_UNLOCK (element);
556 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
557 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
558 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
562 * gst_element_get_start_time:
563 * @element: a #GstElement.
565 * Returns the start time of the element. The start time is the
566 * running time of the clock when this element was last put to PAUSED.
568 * Usually the start_time is managed by a toplevel element such as
573 * Returns: the start time of the element.
578 gst_element_get_start_time (GstElement * element)
582 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
584 GST_OBJECT_LOCK (element);
585 result = GST_ELEMENT_START_TIME (element);
586 GST_OBJECT_UNLOCK (element);
592 * gst_element_is_indexable:
593 * @element: a #GstElement.
595 * Queries if the element can be indexed.
597 * Returns: TRUE if the element can be indexed.
602 gst_element_is_indexable (GstElement * element)
606 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
608 result = (GST_ELEMENT_GET_CLASS (element)->set_index != NULL);
614 * gst_element_set_index:
615 * @element: a #GstElement.
616 * @index: (transfer none): a #GstIndex.
618 * Set @index on the element. The refcount of the index
619 * will be increased, any previously set index is unreffed.
624 gst_element_set_index (GstElement * element, GstIndex * index)
626 GstElementClass *oclass;
628 g_return_if_fail (GST_IS_ELEMENT (element));
629 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
631 oclass = GST_ELEMENT_GET_CLASS (element);
633 if (oclass->set_index)
634 oclass->set_index (element, index);
638 * gst_element_get_index:
639 * @element: a #GstElement.
641 * Gets the index from the element.
643 * Returns: (transfer full): a #GstIndex or %NULL when no index was set on the
644 * element. unref after usage.
649 gst_element_get_index (GstElement * element)
651 GstElementClass *oclass;
652 GstIndex *result = NULL;
654 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
656 oclass = GST_ELEMENT_GET_CLASS (element);
658 if (oclass->get_index)
659 result = oclass->get_index (element);
665 * gst_element_add_pad:
666 * @element: a #GstElement to add the pad to.
667 * @pad: (transfer full): the #GstPad to add to the element.
669 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
670 * see gst_object_set_parent() for refcounting information.
672 * Pads are not automatically activated so elements should perform the needed
673 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
674 * state. See gst_pad_set_active() for more information about activating pads.
676 * The pad and the element should be unlocked when calling this function.
678 * This function will emit the #GstElement::pad-added signal on the element.
680 * Returns: %TRUE if the pad could be added. This function can fail when
681 * a pad with the same name already existed or the pad already had another
687 gst_element_add_pad (GstElement * element, GstPad * pad)
692 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
693 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
695 /* locking pad to look at the name */
696 GST_OBJECT_LOCK (pad);
697 pad_name = g_strdup (GST_PAD_NAME (pad));
698 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
699 GST_STR_NULL (pad_name));
700 flushing = GST_PAD_IS_FLUSHING (pad);
701 GST_OBJECT_UNLOCK (pad);
703 /* then check to see if there's already a pad by that name here */
704 GST_OBJECT_LOCK (element);
705 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
708 /* try to set the pad's parent */
709 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
710 GST_OBJECT_CAST (element))))
713 /* check for flushing pads */
714 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
715 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
716 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
717 "use gst_pad_set_active(pad,TRUE) before adding it.",
718 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
720 GST_OBJECT_LOCK (pad);
721 GST_PAD_UNSET_FLUSHING (pad);
722 GST_OBJECT_UNLOCK (pad);
727 /* add it to the list */
728 switch (gst_pad_get_direction (pad)) {
730 element->srcpads = g_list_prepend (element->srcpads, pad);
731 element->numsrcpads++;
734 element->sinkpads = g_list_prepend (element->sinkpads, pad);
735 element->numsinkpads++;
740 element->pads = g_list_prepend (element->pads, pad);
742 element->pads_cookie++;
743 GST_OBJECT_UNLOCK (element);
745 /* emit the PAD_ADDED signal */
746 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
753 g_critical ("Padname %s is not unique in element %s, not adding",
754 pad_name, GST_ELEMENT_NAME (element));
755 GST_OBJECT_UNLOCK (element);
762 ("Pad %s already has parent when trying to add to element %s",
763 pad_name, GST_ELEMENT_NAME (element));
764 GST_OBJECT_UNLOCK (element);
770 GST_OBJECT_LOCK (pad);
772 ("Trying to add pad %s to element %s, but it has no direction",
773 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
774 GST_OBJECT_UNLOCK (pad);
775 GST_OBJECT_UNLOCK (element);
781 * gst_element_remove_pad:
782 * @element: a #GstElement to remove pad from.
783 * @pad: (transfer none): the #GstPad to remove from the element.
785 * Removes @pad from @element. @pad will be destroyed if it has not been
786 * referenced elsewhere using gst_object_unparent().
788 * This function is used by plugin developers and should not be used
789 * by applications. Pads that were dynamically requested from elements
790 * with gst_element_get_request_pad() should be released with the
791 * gst_element_release_request_pad() function instead.
793 * Pads are not automatically deactivated so elements should perform the needed
794 * steps to deactivate the pad in case this pad is removed in the PAUSED or
795 * PLAYING state. See gst_pad_set_active() for more information about
798 * The pad and the element should be unlocked when calling this function.
800 * This function will emit the #GstElement::pad-removed signal on the element.
802 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
803 * pad does not belong to the provided element.
808 gst_element_remove_pad (GstElement * element, GstPad * pad)
812 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
813 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
815 /* locking pad to look at the name and parent */
816 GST_OBJECT_LOCK (pad);
817 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
818 GST_STR_NULL (GST_PAD_NAME (pad)));
820 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
822 GST_OBJECT_UNLOCK (pad);
825 if ((peer = gst_pad_get_peer (pad))) {
826 /* window for MT unsafeness, someone else could unlink here
827 * and then we call unlink with wrong pads. The unlink
828 * function would catch this and safely return failed. */
829 if (GST_PAD_IS_SRC (pad))
830 gst_pad_unlink (pad, peer);
832 gst_pad_unlink (peer, pad);
834 gst_object_unref (peer);
837 GST_OBJECT_LOCK (element);
838 /* remove it from the list */
839 switch (gst_pad_get_direction (pad)) {
841 element->srcpads = g_list_remove (element->srcpads, pad);
842 element->numsrcpads--;
845 element->sinkpads = g_list_remove (element->sinkpads, pad);
846 element->numsinkpads--;
849 g_critical ("Removing pad without direction???");
852 element->pads = g_list_remove (element->pads, pad);
854 element->pads_cookie++;
855 GST_OBJECT_UNLOCK (element);
857 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
858 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
860 gst_object_unparent (GST_OBJECT_CAST (pad));
867 /* locking order is element > pad */
868 GST_OBJECT_UNLOCK (pad);
870 GST_OBJECT_LOCK (element);
871 GST_OBJECT_LOCK (pad);
872 g_critical ("Padname %s:%s does not belong to element %s when removing",
873 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
874 GST_OBJECT_UNLOCK (pad);
875 GST_OBJECT_UNLOCK (element);
881 * gst_element_no_more_pads:
882 * @element: a #GstElement
884 * Use this function to signal that the element does not expect any more pads
885 * to show up in the current pipeline. This function should be called whenever
886 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
887 * pad templates use this in combination with autopluggers to figure out that
888 * the element is done initializing its pads.
890 * This function emits the #GstElement::no-more-pads signal.
895 gst_element_no_more_pads (GstElement * element)
897 g_return_if_fail (GST_IS_ELEMENT (element));
899 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
903 pad_compare_name (GstPad * pad1, const gchar * name)
907 GST_OBJECT_LOCK (pad1);
908 result = strcmp (GST_PAD_NAME (pad1), name);
909 GST_OBJECT_UNLOCK (pad1);
915 * gst_element_get_static_pad:
916 * @element: a #GstElement to find a static pad of.
917 * @name: the name of the static #GstPad to retrieve.
919 * Retrieves a pad from @element by name. This version only retrieves
920 * already-existing (i.e. 'static') pads.
922 * Returns: (transfer full): the requested #GstPad if found, otherwise %NULL.
928 gst_element_get_static_pad (GstElement * element, const gchar * name)
931 GstPad *result = NULL;
933 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
934 g_return_val_if_fail (name != NULL, NULL);
936 GST_OBJECT_LOCK (element);
938 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
940 result = GST_PAD_CAST (find->data);
941 gst_object_ref (result);
944 if (result == NULL) {
945 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
946 name, GST_ELEMENT_NAME (element));
948 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
949 GST_ELEMENT_NAME (element), name);
951 GST_OBJECT_UNLOCK (element);
957 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
958 const gchar * name, const GstCaps * caps)
960 GstPad *newpad = NULL;
961 GstElementClass *oclass;
963 oclass = GST_ELEMENT_GET_CLASS (element);
965 #ifndef G_DISABLE_CHECKS
966 /* Some sanity checking here */
970 /* Is this the template name? */
971 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
972 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
974 const gchar *str, *data;
977 /* Otherwise check if it's a valid name for the name template */
978 str = strchr (templ->name_template, '%');
979 g_return_val_if_fail (str != NULL, NULL);
980 g_return_val_if_fail (strncmp (templ->name_template, name,
981 str - templ->name_template) == 0, NULL);
982 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
984 data = name + (str - templ->name_template);
986 /* Can either be %s or %d or %u, do sanity checking for %d */
987 if (*(str + 1) == 'd') {
991 tmp = g_ascii_strtoll (data, &endptr, 10);
992 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
993 && *endptr == '\0', NULL);
994 } else if (*(str + 1) == 'u') {
998 tmp = g_ascii_strtoull (data, &endptr, 10);
999 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
1003 pad = gst_element_get_static_pad (element, name);
1005 gst_object_unref (pad);
1006 /* FIXME 0.11: Change this to g_return_val_if_fail() */
1007 g_critical ("Element %s already has a pad named %s, the behaviour of "
1008 " gst_element_get_request_pad() for existing pads is undefined!",
1009 GST_ELEMENT_NAME (element), name);
1014 if (oclass->request_new_pad)
1015 newpad = (oclass->request_new_pad) (element, templ, name, caps);
1018 gst_object_ref (newpad);
1024 * gst_element_get_request_pad:
1025 * @element: a #GstElement to find a request pad of.
1026 * @name: the name of the request #GstPad to retrieve.
1028 * Retrieves a pad from the element by name (e.g. "src_\%d"). This version only
1029 * retrieves request pads. The pad should be released with
1030 * gst_element_release_request_pad().
1032 * This method is slow and will be deprecated in the future. New code should
1033 * use gst_element_request_pad() with the requested template.
1035 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1036 * Release after usage.
1039 gst_element_get_request_pad (GstElement * element, const gchar * name)
1041 GstPadTemplate *templ = NULL;
1043 const gchar *req_name = NULL;
1044 gboolean templ_found = FALSE;
1047 gchar *str, *endptr = NULL;
1048 GstElementClass *class;
1050 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1051 g_return_val_if_fail (name != NULL, NULL);
1053 class = GST_ELEMENT_GET_CLASS (element);
1055 /* if the name contains a %, we assume it's the complete template name. Get
1056 * the template and try to get a pad */
1057 if (strstr (name, "%")) {
1058 templ = gst_element_class_get_request_pad_template (class, name);
1063 /* there is no % in the name, try to find a matching template */
1064 list = class->padtemplates;
1065 while (!templ_found && list) {
1066 templ = (GstPadTemplate *) list->data;
1067 if (templ->presence == GST_PAD_REQUEST) {
1068 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1069 templ->name_template);
1070 /* see if we find an exact match */
1071 if (strcmp (name, templ->name_template) == 0) {
1076 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1077 and %d and %u, occurring at the end of the name_template, are the only
1079 else if ((str = strchr (templ->name_template, '%'))
1080 && strncmp (templ->name_template, name,
1081 str - templ->name_template) == 0
1082 && strlen (name) > str - templ->name_template) {
1083 data = name + (str - templ->name_template);
1084 if (*(str + 1) == 'd') {
1088 tmp = strtol (data, &endptr, 10);
1089 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1095 } else if (*(str + 1) == 'u') {
1099 tmp = strtoul (data, &endptr, 10);
1100 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1120 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1126 * gst_element_request_pad:
1127 * @element: a #GstElement to find a request pad of.
1128 * @templ: a #GstPadTemplate of which we want a pad of.
1129 * @name: (transfer none) (allow-none): the name of the request #GstPad
1130 * to retrieve. Can be %NULL.
1131 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1132 * request. Can be %NULL.
1134 * Retrieves a request pad from the element according to the provided template.
1135 * Pad templates can be looked up using
1136 * gst_element_factory_get_static_pad_templates().
1138 * If the @caps are specified and the element implements thew new
1139 * request_new_pad_full virtual method, the element will use them to select
1140 * which pad to create.
1142 * The pad should be released with gst_element_release_request_pad().
1144 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1145 * Release after usage.
1150 gst_element_request_pad (GstElement * element,
1151 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1153 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1154 g_return_val_if_fail (templ != NULL, NULL);
1156 return _gst_element_request_pad (element, templ, name, caps);
1159 static GstIterator *
1160 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1162 GstIterator *result;
1164 GST_OBJECT_LOCK (element);
1165 result = gst_iterator_new_list (GST_TYPE_PAD,
1166 GST_OBJECT_GET_LOCK (element),
1167 &element->pads_cookie, padlist, (GObject *) element, NULL);
1168 GST_OBJECT_UNLOCK (element);
1174 * gst_element_iterate_pads:
1175 * @element: a #GstElement to iterate pads of.
1177 * Retrieves an iterator of @element's pads. The iterator should
1178 * be freed after usage. Also more specialized iterators exists such as
1179 * gst_element_iterate_src_pads() or gst_element_iterate_sink_pads().
1181 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1187 gst_element_iterate_pads (GstElement * element)
1189 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1191 return gst_element_iterate_pad_list (element, &element->pads);
1195 * gst_element_iterate_src_pads:
1196 * @element: a #GstElement.
1198 * Retrieves an iterator of @element's source pads.
1200 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1206 gst_element_iterate_src_pads (GstElement * element)
1208 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1210 return gst_element_iterate_pad_list (element, &element->srcpads);
1214 * gst_element_iterate_sink_pads:
1215 * @element: a #GstElement.
1217 * Retrieves an iterator of @element's sink pads.
1219 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1225 gst_element_iterate_sink_pads (GstElement * element)
1227 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1229 return gst_element_iterate_pad_list (element, &element->sinkpads);
1233 * gst_element_class_add_pad_template:
1234 * @klass: the #GstElementClass to add the pad template to.
1235 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1237 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1238 * functions of classes. If a pad template with the same name as an already
1239 * existing one is added the old one is replaced by the new one.
1243 gst_element_class_add_pad_template (GstElementClass * klass,
1244 GstPadTemplate * templ)
1246 GList *template_list = klass->padtemplates;
1248 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1249 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1251 /* If we already have a pad template with the same name replace the
1253 while (template_list) {
1254 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1256 /* Found pad with the same name, replace and return */
1257 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1258 gst_object_unref (padtempl);
1259 template_list->data = templ;
1262 template_list = g_list_next (template_list);
1265 /* Take ownership of the floating ref */
1266 g_object_ref_sink (templ);
1268 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1269 klass->numpadtemplates++;
1273 * gst_element_class_add_metadata:
1274 * @klass: class to set metadata for
1275 * @key: the key to set
1276 * @value: the value to set
1278 * Set @key with @value as metadata in @klass.
1281 gst_element_class_add_metadata (GstElementClass * klass,
1282 const gchar * key, const gchar * value)
1284 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1285 g_return_if_fail (key != NULL);
1286 g_return_if_fail (value != NULL);
1288 gst_structure_set ((GstStructure *) klass->metadata,
1289 key, G_TYPE_STRING, value, NULL);
1293 * gst_element_class_set_metadata:
1294 * @klass: class to set metadata for
1295 * @longname: The long English name of the element. E.g. "File Sink"
1296 * @classification: String describing the type of element, as an unordered list
1297 * separated with slashes ('/'). See draft-klass.txt of the design docs
1298 * for more details and common types. E.g: "Sink/File"
1299 * @description: Sentence describing the purpose of the element.
1300 * E.g: "Write stream to a file"
1301 * @author: Name and contact details of the author(s). Use \n to separate
1302 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1304 * Sets the detailed information for a #GstElementClass.
1305 * <note>This function is for use in _class_init functions only.</note>
1308 gst_element_class_set_metadata (GstElementClass * klass,
1309 const gchar * longname, const gchar * classification,
1310 const gchar * description, const gchar * author)
1312 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1314 gst_structure_set ((GstStructure *) klass->metadata,
1315 GST_ELEMENT_METADATA_LONGNAME, G_TYPE_STRING, longname,
1316 GST_ELEMENT_METADATA_KLASS, G_TYPE_STRING, classification,
1317 GST_ELEMENT_METADATA_DESCRIPTION, G_TYPE_STRING, description,
1318 GST_ELEMENT_METADATA_AUTHOR, G_TYPE_STRING, author, NULL);
1322 * gst_element_class_get_metadata:
1323 * @klass: class to get metadata for
1324 * @key: the key to get
1326 * Get metadata with @key in @klass.
1328 * Returns: the metadata for @key.
1331 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1333 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1334 g_return_val_if_fail (key != NULL, NULL);
1336 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1340 * gst_element_class_get_pad_template_list:
1341 * @element_class: a #GstElementClass to get pad templates of.
1343 * Retrieves a list of the pad templates associated with @element_class. The
1344 * list must not be modified by the calling code.
1345 * <note>If you use this function in the #GInstanceInitFunc of an object class
1346 * that has subclasses, make sure to pass the g_class parameter of the
1347 * #GInstanceInitFunc here.</note>
1349 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1353 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1355 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1357 return element_class->padtemplates;
1361 * gst_element_class_get_pad_template:
1362 * @element_class: a #GstElementClass to get the pad template of.
1363 * @name: the name of the #GstPadTemplate to get.
1365 * Retrieves a padtemplate from @element_class with the given name.
1366 * <note>If you use this function in the #GInstanceInitFunc of an object class
1367 * that has subclasses, make sure to pass the g_class parameter of the
1368 * #GInstanceInitFunc here.</note>
1370 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1371 * if none was found. No unreferencing is necessary.
1374 gst_element_class_get_pad_template (GstElementClass *
1375 element_class, const gchar * name)
1379 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1380 g_return_val_if_fail (name != NULL, NULL);
1382 padlist = element_class->padtemplates;
1385 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1387 if (strcmp (padtempl->name_template, name) == 0)
1390 padlist = g_list_next (padlist);
1396 static GstPadTemplate *
1397 gst_element_class_get_request_pad_template (GstElementClass *
1398 element_class, const gchar * name)
1400 GstPadTemplate *tmpl;
1402 tmpl = gst_element_class_get_pad_template (element_class, name);
1403 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1409 /* get a random pad on element of the given direction.
1410 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1413 gst_element_get_random_pad (GstElement * element,
1414 gboolean need_linked, GstPadDirection dir)
1416 GstPad *result = NULL;
1419 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1423 GST_OBJECT_LOCK (element);
1424 pads = element->srcpads;
1427 GST_OBJECT_LOCK (element);
1428 pads = element->sinkpads;
1431 goto wrong_direction;
1433 for (; pads; pads = g_list_next (pads)) {
1434 GstPad *pad = GST_PAD_CAST (pads->data);
1436 GST_OBJECT_LOCK (pad);
1437 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1438 GST_DEBUG_PAD_NAME (pad));
1440 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1441 /* if we require a linked pad, and it is not linked, continue the
1443 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1444 GST_DEBUG_PAD_NAME (pad));
1445 GST_OBJECT_UNLOCK (pad);
1448 /* found a pad, stop search */
1449 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1450 GST_DEBUG_PAD_NAME (pad));
1451 GST_OBJECT_UNLOCK (pad);
1457 gst_object_ref (result);
1459 GST_OBJECT_UNLOCK (element);
1463 /* ERROR handling */
1466 g_warning ("unknown pad direction %d", dir);
1472 gst_element_default_send_event (GstElement * element, GstEvent * event)
1474 gboolean result = FALSE;
1477 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1478 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1479 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1482 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1483 "pushing %s event to random %s pad %s:%s",
1484 GST_EVENT_TYPE_NAME (event),
1485 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1486 GST_DEBUG_PAD_NAME (pad));
1488 result = gst_pad_push_event (pad, event);
1489 gst_object_unref (pad);
1491 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1492 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1493 gst_event_unref (event);
1499 * gst_element_send_event:
1500 * @element: a #GstElement to send the event to.
1501 * @event: (transfer full): the #GstEvent to send to the element.
1503 * Sends an event to an element. If the element doesn't implement an
1504 * event handler, the event will be pushed on a random linked sink pad for
1505 * upstream events or a random linked source pad for downstream events.
1507 * This function takes owership of the provided event so you should
1508 * gst_event_ref() it if you want to reuse the event after this call.
1510 * Returns: %TRUE if the event was handled.
1515 gst_element_send_event (GstElement * element, GstEvent * event)
1517 GstElementClass *oclass;
1518 gboolean result = FALSE;
1520 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1521 g_return_val_if_fail (event != NULL, FALSE);
1523 oclass = GST_ELEMENT_GET_CLASS (element);
1525 GST_STATE_LOCK (element);
1526 if (oclass->send_event) {
1527 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1528 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1529 result = oclass->send_event (element, event);
1531 result = gst_element_default_send_event (element, event);
1533 GST_STATE_UNLOCK (element);
1540 * @element: a #GstElement to send the event to.
1541 * @rate: The new playback rate
1542 * @format: The format of the seek values
1543 * @flags: The optional seek flags.
1544 * @cur_type: The type and flags for the new current position
1545 * @cur: The value of the new current position
1546 * @stop_type: The type and flags for the new stop position
1547 * @stop: The value of the new stop position
1549 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1550 * the parameters. The seek event is sent to the element using
1551 * gst_element_send_event().
1553 * Returns: %TRUE if the event was handled.
1558 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1559 GstSeekFlags flags, GstSeekType cur_type, gint64 cur,
1560 GstSeekType stop_type, gint64 stop)
1565 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1568 gst_event_new_seek (rate, format, flags, cur_type, cur, stop_type, stop);
1569 result = gst_element_send_event (element, event);
1575 * gst_element_get_query_types:
1576 * @element: a #GstElement to query
1578 * Get an array of query types from the element.
1579 * If the element doesn't implement a query types function,
1580 * the query will be forwarded to the peer of a random linked sink pad.
1582 * Returns: An array of #GstQueryType elements that should not
1583 * be freed or modified.
1587 const GstQueryType *
1588 gst_element_get_query_types (GstElement * element)
1590 GstElementClass *oclass;
1591 const GstQueryType *result = NULL;
1593 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1595 oclass = GST_ELEMENT_GET_CLASS (element);
1597 if (oclass->get_query_types) {
1598 result = oclass->get_query_types (element);
1600 GstPad *pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1603 GstPad *peer = gst_pad_get_peer (pad);
1606 result = gst_pad_get_query_types (peer);
1608 gst_object_unref (peer);
1610 gst_object_unref (pad);
1617 gst_element_default_query (GstElement * element, GstQuery * query)
1619 gboolean result = FALSE;
1622 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1624 result = gst_pad_query (pad, query);
1626 gst_object_unref (pad);
1628 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1630 GstPad *peer = gst_pad_get_peer (pad);
1633 result = gst_pad_query (peer, query);
1635 gst_object_unref (peer);
1637 gst_object_unref (pad);
1644 * gst_element_query:
1645 * @element: a #GstElement to perform the query on.
1646 * @query: (transfer none): the #GstQuery.
1648 * Performs a query on the given element.
1650 * For elements that don't implement a query handler, this function
1651 * forwards the query to a random srcpad or to the peer of a
1652 * random linked sinkpad of this element.
1654 * Please note that some queries might need a running pipeline to work.
1656 * Returns: TRUE if the query could be performed.
1661 gst_element_query (GstElement * element, GstQuery * query)
1663 GstElementClass *oclass;
1664 gboolean result = FALSE;
1666 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1667 g_return_val_if_fail (query != NULL, FALSE);
1669 oclass = GST_ELEMENT_GET_CLASS (element);
1671 if (oclass->query) {
1672 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1673 GST_ELEMENT_NAME (element));
1674 result = oclass->query (element, query);
1676 result = gst_element_default_query (element, query);
1682 * gst_element_post_message:
1683 * @element: a #GstElement posting the message
1684 * @message: (transfer full): a #GstMessage to post
1686 * Post a message on the element's #GstBus. This function takes ownership of the
1687 * message; if you want to access the message after this call, you should add an
1688 * additional reference before calling.
1690 * Returns: %TRUE if the message was successfully posted. The function returns
1691 * %FALSE if the element did not have a bus.
1696 gst_element_post_message (GstElement * element, GstMessage * message)
1699 gboolean result = FALSE;
1701 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1702 g_return_val_if_fail (message != NULL, FALSE);
1704 GST_OBJECT_LOCK (element);
1707 if (G_UNLIKELY (bus == NULL))
1710 gst_object_ref (bus);
1711 GST_OBJECT_UNLOCK (element);
1713 /* we release the element lock when posting the message so that any
1714 * (synchronous) message handlers can operate on the element */
1715 result = gst_bus_post (bus, message);
1716 gst_object_unref (bus);
1723 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1724 "not posting message %p: no bus", message);
1725 GST_OBJECT_UNLOCK (element);
1726 gst_message_unref (message);
1732 * _gst_element_error_printf:
1733 * @format: the printf-like format to use, or %NULL
1735 * This function is only used internally by the gst_element_error() macro.
1737 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1743 _gst_element_error_printf (const gchar * format, ...)
1753 va_start (args, format);
1754 buffer = g_strdup_vprintf (format, args);
1760 * gst_element_message_full:
1761 * @element: a #GstElement to send message from
1762 * @type: the #GstMessageType
1763 * @domain: the GStreamer GError domain this message belongs to
1764 * @code: the GError code belonging to the domain
1765 * @text: (allow-none) (transfer full): an allocated text string to be used
1766 * as a replacement for the default message connected to code,
1768 * @debug: (allow-none) (transfer full): an allocated debug message to be
1769 * used as a replacement for the default debugging information,
1771 * @file: the source code file where the error was generated
1772 * @function: the source code function where the error was generated
1773 * @line: the source code line where the error was generated
1775 * Post an error, warning or info message on the bus from inside an element.
1777 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1778 * #GST_MESSAGE_INFO.
1782 void gst_element_message_full
1783 (GstElement * element, GstMessageType type,
1784 GQuark domain, gint code, gchar * text,
1785 gchar * debug, const gchar * file, const gchar * function, gint line)
1787 GError *gerror = NULL;
1791 gboolean has_debug = TRUE;
1792 GstMessage *message = NULL;
1795 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1796 g_return_if_fail (GST_IS_ELEMENT (element));
1797 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1798 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1800 /* check if we send the given text or the default error text */
1801 if ((text == NULL) || (text[0] == 0)) {
1802 /* text could have come from g_strdup_printf (""); */
1804 sent_text = gst_error_get_message (domain, code);
1808 /* construct a sent_debug with extra information from source */
1809 if ((debug == NULL) || (debug[0] == 0)) {
1810 /* debug could have come from g_strdup_printf (""); */
1814 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1816 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1817 file, line, function, name, debug);
1819 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1820 file, line, function, name);
1824 /* create gerror and post message */
1825 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1827 gerror = g_error_new_literal (domain, code, sent_text);
1830 case GST_MESSAGE_ERROR:
1832 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1834 case GST_MESSAGE_WARNING:
1835 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1838 case GST_MESSAGE_INFO:
1839 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1843 g_assert_not_reached ();
1846 gst_element_post_message (element, message);
1848 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1849 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1852 g_error_free (gerror);
1853 g_free (sent_debug);
1858 * gst_element_is_locked_state:
1859 * @element: a #GstElement.
1861 * Checks if the state of an element is locked.
1862 * If the state of an element is locked, state changes of the parent don't
1863 * affect the element.
1864 * This way you can leave currently unused elements inside bins. Just lock their
1865 * state before changing the state from #GST_STATE_NULL.
1869 * Returns: TRUE, if the element's state is locked.
1872 gst_element_is_locked_state (GstElement * element)
1876 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1878 GST_OBJECT_LOCK (element);
1879 result = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1880 GST_OBJECT_UNLOCK (element);
1886 * gst_element_set_locked_state:
1887 * @element: a #GstElement
1888 * @locked_state: TRUE to lock the element's state
1890 * Locks the state of an element, so state changes of the parent don't affect
1891 * this element anymore.
1895 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1896 * or the elements state-locking needed no change.
1899 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1903 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1905 GST_OBJECT_LOCK (element);
1906 old = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1908 if (G_UNLIKELY (old == locked_state))
1912 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1913 GST_ELEMENT_NAME (element));
1914 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_LOCKED_STATE);
1916 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1917 GST_ELEMENT_NAME (element));
1918 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_LOCKED_STATE);
1920 GST_OBJECT_UNLOCK (element);
1926 GST_CAT_DEBUG (GST_CAT_STATES,
1927 "elements %s was already in locked state %d",
1928 GST_ELEMENT_NAME (element), old);
1929 GST_OBJECT_UNLOCK (element);
1936 * gst_element_sync_state_with_parent:
1937 * @element: a #GstElement.
1939 * Tries to change the state of the element to the same as its parent.
1940 * If this function returns FALSE, the state of element is undefined.
1942 * Returns: TRUE, if the element's state could be synced to the parent's state.
1947 gst_element_sync_state_with_parent (GstElement * element)
1951 GstStateChangeReturn ret;
1953 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1955 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1956 GstState parent_current, parent_pending;
1958 GST_OBJECT_LOCK (parent);
1959 parent_current = GST_STATE (parent);
1960 parent_pending = GST_STATE_PENDING (parent);
1961 GST_OBJECT_UNLOCK (parent);
1963 /* set to pending if there is one, else we set it to the current state of
1965 if (parent_pending != GST_STATE_VOID_PENDING)
1966 target = parent_pending;
1968 target = parent_current;
1970 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1971 "syncing state (%s) to parent %s %s (%s, %s)",
1972 gst_element_state_get_name (GST_STATE (element)),
1973 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1974 gst_element_state_get_name (parent_current),
1975 gst_element_state_get_name (parent_pending));
1977 ret = gst_element_set_state (element, target);
1978 if (ret == GST_STATE_CHANGE_FAILURE)
1981 gst_object_unref (parent);
1985 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
1992 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1993 "syncing state failed (%s)",
1994 gst_element_state_change_return_get_name (ret));
1995 gst_object_unref (parent);
2001 static GstStateChangeReturn
2002 gst_element_get_state_func (GstElement * element,
2003 GstState * state, GstState * pending, GstClockTime timeout)
2005 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2006 GstState old_pending;
2008 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2009 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2011 GST_OBJECT_LOCK (element);
2012 ret = GST_STATE_RETURN (element);
2013 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2014 gst_element_state_change_return_get_name (ret));
2016 /* we got an error, report immediately */
2017 if (ret == GST_STATE_CHANGE_FAILURE)
2020 /* we got no_preroll, report immediately */
2021 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2024 /* no need to wait async if we are not async */
2025 if (ret != GST_STATE_CHANGE_ASYNC)
2028 old_pending = GST_STATE_PENDING (element);
2029 if (old_pending != GST_STATE_VOID_PENDING) {
2030 GTimeVal *timeval, abstimeout;
2033 if (timeout != GST_CLOCK_TIME_NONE) {
2034 glong add = timeout / 1000;
2039 /* make timeout absolute */
2040 g_get_current_time (&abstimeout);
2041 g_time_val_add (&abstimeout, add);
2042 timeval = &abstimeout;
2046 /* get cookie to detect state changes during waiting */
2047 cookie = element->state_cookie;
2049 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2050 "waiting for element to commit state");
2052 /* we have a pending state change, wait for it to complete */
2053 if (!GST_STATE_TIMED_WAIT (element, timeval)) {
2054 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2055 /* timeout triggered */
2056 ret = GST_STATE_CHANGE_ASYNC;
2058 if (cookie != element->state_cookie)
2061 /* could be success or failure */
2062 if (old_pending == GST_STATE (element)) {
2063 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2064 ret = GST_STATE_CHANGE_SUCCESS;
2066 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2067 ret = GST_STATE_CHANGE_FAILURE;
2070 /* if nothing is pending anymore we can return SUCCESS */
2071 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2072 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2073 ret = GST_STATE_CHANGE_SUCCESS;
2079 *state = GST_STATE (element);
2081 *pending = GST_STATE_PENDING (element);
2083 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2084 "state current: %s, pending: %s, result: %s",
2085 gst_element_state_get_name (GST_STATE (element)),
2086 gst_element_state_get_name (GST_STATE_PENDING (element)),
2087 gst_element_state_change_return_get_name (ret));
2088 GST_OBJECT_UNLOCK (element);
2095 *state = GST_STATE_VOID_PENDING;
2097 *pending = GST_STATE_VOID_PENDING;
2099 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2101 GST_OBJECT_UNLOCK (element);
2103 return GST_STATE_CHANGE_FAILURE;
2108 * gst_element_get_state:
2109 * @element: a #GstElement to get the state of.
2110 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2112 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2113 * state. Can be %NULL.
2114 * @timeout: a #GstClockTime to specify the timeout for an async
2115 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2117 * Gets the state of the element.
2119 * For elements that performed an ASYNC state change, as reported by
2120 * gst_element_set_state(), this function will block up to the
2121 * specified timeout value for the state change to complete.
2122 * If the element completes the state change or goes into
2123 * an error, this function returns immediately with a return value of
2124 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2126 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2127 * returns the current and pending state immediately.
2129 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2130 * successfully changed its state but is not able to provide data yet.
2131 * This mostly happens for live sources that only produce data in
2132 * %GST_STATE_PLAYING. While the state change return is equivalent to
2133 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2134 * some sink elements might not be able to complete their state change because
2135 * an element is not producing data to complete the preroll. When setting the
2136 * element to playing, the preroll will complete and playback will start.
2138 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2139 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2140 * element is still performing a state change or
2141 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2145 GstStateChangeReturn
2146 gst_element_get_state (GstElement * element,
2147 GstState * state, GstState * pending, GstClockTime timeout)
2149 GstElementClass *oclass;
2150 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2152 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2154 oclass = GST_ELEMENT_GET_CLASS (element);
2156 if (oclass->get_state)
2157 result = (oclass->get_state) (element, state, pending, timeout);
2163 * gst_element_abort_state:
2164 * @element: a #GstElement to abort the state of.
2166 * Abort the state change of the element. This function is used
2167 * by elements that do asynchronous state changes and find out
2168 * something is wrong.
2170 * This function should be called with the STATE_LOCK held.
2175 gst_element_abort_state (GstElement * element)
2179 #ifndef GST_DISABLE_GST_DEBUG
2183 g_return_if_fail (GST_IS_ELEMENT (element));
2185 GST_OBJECT_LOCK (element);
2186 pending = GST_STATE_PENDING (element);
2188 if (pending == GST_STATE_VOID_PENDING ||
2189 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2190 goto nothing_aborted;
2192 #ifndef GST_DISABLE_GST_DEBUG
2193 old_state = GST_STATE (element);
2195 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2196 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2197 gst_element_state_get_name (pending));
2201 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2203 GST_STATE_BROADCAST (element);
2204 GST_OBJECT_UNLOCK (element);
2210 GST_OBJECT_UNLOCK (element);
2215 /* Not static because GstBin has manual state handling too */
2217 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2218 GstState newstate, GstState pending)
2220 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2221 GstMessage *message;
2223 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2224 "notifying about state-changed %s to %s (%s pending)",
2225 gst_element_state_get_name (oldstate),
2226 gst_element_state_get_name (newstate),
2227 gst_element_state_get_name (pending));
2229 if (klass->state_changed)
2230 klass->state_changed (element, oldstate, newstate, pending);
2232 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2233 oldstate, newstate, pending);
2234 gst_element_post_message (element, message);
2238 * gst_element_continue_state:
2239 * @element: a #GstElement to continue the state change of.
2240 * @ret: The previous state return value
2242 * Commit the state change of the element and proceed to the next
2243 * pending state if any. This function is used
2244 * by elements that do asynchronous state changes.
2245 * The core will normally call this method automatically when an
2246 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2248 * If after calling this method the element still has not reached
2249 * the pending state, the next state change is performed.
2251 * This method is used internally and should normally not be called by plugins
2254 * Returns: The result of the commit state change.
2258 GstStateChangeReturn
2259 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2261 GstStateChangeReturn old_ret;
2262 GstState old_state, old_next;
2263 GstState current, next, pending;
2264 GstStateChange transition;
2266 GST_OBJECT_LOCK (element);
2267 old_ret = GST_STATE_RETURN (element);
2268 GST_STATE_RETURN (element) = ret;
2269 pending = GST_STATE_PENDING (element);
2271 /* check if there is something to commit */
2272 if (pending == GST_STATE_VOID_PENDING)
2273 goto nothing_pending;
2275 old_state = GST_STATE (element);
2276 /* this is the state we should go to next */
2277 old_next = GST_STATE_NEXT (element);
2278 /* update current state */
2279 current = GST_STATE (element) = old_next;
2281 /* see if we reached the final state */
2282 if (pending == current)
2285 next = GST_STATE_GET_NEXT (current, pending);
2286 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2288 GST_STATE_NEXT (element) = next;
2290 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2291 GST_OBJECT_UNLOCK (element);
2293 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2294 "committing state from %s to %s, pending %s, next %s",
2295 gst_element_state_get_name (old_state),
2296 gst_element_state_get_name (old_next),
2297 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2299 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2301 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2302 "continue state change %s to %s, final %s",
2303 gst_element_state_get_name (current),
2304 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2306 ret = gst_element_change_state (element, transition);
2312 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2313 GST_OBJECT_UNLOCK (element);
2318 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2319 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2321 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2322 "completed state change to %s", gst_element_state_get_name (pending));
2323 GST_OBJECT_UNLOCK (element);
2325 /* don't post silly messages with the same state. This can happen
2326 * when an element state is changed to what it already was. For bins
2327 * this can be the result of a lost state, which we check with the
2328 * previous return value.
2329 * We do signal the cond though as a _get_state() might be blocking
2331 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2332 _priv_gst_element_state_changed (element, old_state, old_next,
2333 GST_STATE_VOID_PENDING);
2335 GST_STATE_BROADCAST (element);
2342 * gst_element_lost_state:
2343 * @element: a #GstElement the state is lost of
2345 * Brings the element to the lost state. The current state of the
2346 * element is copied to the pending state so that any call to
2347 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2349 * An ASYNC_START message is posted. If the element was PLAYING, it will
2350 * go to PAUSED. The element will be restored to its PLAYING state by
2351 * the parent pipeline when it prerolls again.
2353 * This is mostly used for elements that lost their preroll buffer
2354 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2355 * they will go to their pending state again when a new preroll buffer is
2356 * queued. This function can only be called when the element is currently
2357 * not in error or an async state change.
2359 * This function is used internally and should normally not be called from
2360 * plugins or applications.
2363 gst_element_lost_state (GstElement * element)
2365 GstState old_state, new_state;
2366 GstMessage *message;
2368 g_return_if_fail (GST_IS_ELEMENT (element));
2370 GST_OBJECT_LOCK (element);
2371 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2374 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2375 goto only_async_start;
2377 old_state = GST_STATE (element);
2379 /* when we were PLAYING, the new state is PAUSED. We will also not
2380 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2381 * when we preroll. */
2382 if (old_state > GST_STATE_PAUSED)
2383 new_state = GST_STATE_PAUSED;
2385 new_state = old_state;
2387 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2388 "lost state of %s to %s", gst_element_state_get_name (old_state),
2389 gst_element_state_get_name (new_state));
2391 GST_STATE (element) = new_state;
2392 GST_STATE_NEXT (element) = new_state;
2393 GST_STATE_PENDING (element) = new_state;
2394 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2395 GST_OBJECT_UNLOCK (element);
2397 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2399 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2400 gst_element_post_message (element, message);
2406 GST_OBJECT_UNLOCK (element);
2411 GST_OBJECT_UNLOCK (element);
2413 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2414 gst_element_post_message (element, message);
2420 * gst_element_set_state:
2421 * @element: a #GstElement to change state of.
2422 * @state: the element's new #GstState.
2424 * Sets the state of the element. This function will try to set the
2425 * requested state by going through all the intermediary states and calling
2426 * the class's state change function for each.
2428 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2429 * element will perform the remainder of the state change asynchronously in
2431 * An application can use gst_element_get_state() to wait for the completion
2432 * of the state change or it can wait for a state change message on the bus.
2434 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2435 * #GST_STATE_CHANGE_ASYNC.
2437 * Returns: Result of the state change using #GstStateChangeReturn.
2441 GstStateChangeReturn
2442 gst_element_set_state (GstElement * element, GstState state)
2444 GstElementClass *oclass;
2445 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2447 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2449 oclass = GST_ELEMENT_GET_CLASS (element);
2451 if (oclass->set_state)
2452 result = (oclass->set_state) (element, state);
2458 * default set state function, calculates the next state based
2459 * on current state and calls the change_state function
2461 static GstStateChangeReturn
2462 gst_element_set_state_func (GstElement * element, GstState state)
2464 GstState current, next, old_pending;
2465 GstStateChangeReturn ret;
2466 GstStateChange transition;
2467 GstStateChangeReturn old_ret;
2469 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2471 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2472 gst_element_state_get_name (state));
2474 /* state lock is taken to protect the set_state() and get_state()
2475 * procedures, it does not lock any variables. */
2476 GST_STATE_LOCK (element);
2478 /* now calculate how to get to the new state */
2479 GST_OBJECT_LOCK (element);
2480 old_ret = GST_STATE_RETURN (element);
2481 /* previous state change returned an error, remove all pending
2482 * and next states */
2483 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2484 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2485 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2486 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2489 current = GST_STATE (element);
2490 next = GST_STATE_NEXT (element);
2491 old_pending = GST_STATE_PENDING (element);
2493 /* this is the (new) state we should go to. TARGET is the last state we set on
2495 if (state != GST_STATE_TARGET (element)) {
2496 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2497 "setting target state to %s", gst_element_state_get_name (state));
2498 GST_STATE_TARGET (element) = state;
2499 /* increment state cookie so that we can track each state change. We only do
2500 * this if this is actually a new state change. */
2501 element->state_cookie++;
2503 GST_STATE_PENDING (element) = state;
2505 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2506 "current %s, old_pending %s, next %s, old return %s",
2507 gst_element_state_get_name (current),
2508 gst_element_state_get_name (old_pending),
2509 gst_element_state_get_name (next),
2510 gst_element_state_change_return_get_name (old_ret));
2512 /* if the element was busy doing a state change, we just update the
2513 * target state, it'll get to it async then. */
2514 if (old_pending != GST_STATE_VOID_PENDING) {
2515 /* upwards state change will happen ASYNC */
2516 if (old_pending <= state)
2518 /* element is going to this state already */
2519 else if (next == state)
2521 /* element was performing an ASYNC upward state change and
2522 * we request to go downward again. Start from the next pending
2524 else if (next > state
2525 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2529 next = GST_STATE_GET_NEXT (current, state);
2530 /* now we store the next state */
2531 GST_STATE_NEXT (element) = next;
2532 /* mark busy, we need to check that there is actually a state change
2533 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2534 * the default element change_state function has no way to know what the
2535 * old value was... could consider this a FIXME...*/
2536 if (current != next)
2537 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2539 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2541 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2542 "%s: setting state from %s to %s",
2543 (next != state ? "intermediate" : "final"),
2544 gst_element_state_get_name (current), gst_element_state_get_name (next));
2546 /* now signal any waiters, they will error since the cookie was incremented */
2547 GST_STATE_BROADCAST (element);
2549 GST_OBJECT_UNLOCK (element);
2551 ret = gst_element_change_state (element, transition);
2553 GST_STATE_UNLOCK (element);
2555 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2556 gst_element_state_change_return_get_name (ret));
2562 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2563 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2564 "element was busy with async state change");
2565 GST_OBJECT_UNLOCK (element);
2567 GST_STATE_UNLOCK (element);
2569 return GST_STATE_CHANGE_ASYNC;
2574 * gst_element_change_state:
2575 * @element: a #GstElement
2576 * @transition: the requested transition
2578 * Perform @transition on @element.
2580 * This function must be called with STATE_LOCK held and is mainly used
2583 * Returns: the #GstStateChangeReturn of the state transition.
2585 GstStateChangeReturn
2586 gst_element_change_state (GstElement * element, GstStateChange transition)
2588 GstElementClass *oclass;
2589 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2591 oclass = GST_ELEMENT_GET_CLASS (element);
2593 /* call the state change function so it can set the state */
2594 if (oclass->change_state)
2595 ret = (oclass->change_state) (element, transition);
2597 ret = GST_STATE_CHANGE_FAILURE;
2600 case GST_STATE_CHANGE_FAILURE:
2601 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2602 "have FAILURE change_state return");
2603 /* state change failure */
2604 gst_element_abort_state (element);
2606 case GST_STATE_CHANGE_ASYNC:
2610 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2611 "element will change state ASYNC");
2613 target = GST_STATE_TARGET (element);
2615 if (target > GST_STATE_READY)
2618 /* else we just continue the state change downwards */
2619 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2620 "forcing commit state %s <= %s",
2621 gst_element_state_get_name (target),
2622 gst_element_state_get_name (GST_STATE_READY));
2624 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2627 case GST_STATE_CHANGE_SUCCESS:
2628 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2629 "element changed state SUCCESS");
2630 /* we can commit the state now which will proceeed to
2632 ret = gst_element_continue_state (element, ret);
2634 case GST_STATE_CHANGE_NO_PREROLL:
2635 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2636 "element changed state NO_PREROLL");
2637 /* we can commit the state now which will proceeed to
2639 ret = gst_element_continue_state (element, ret);
2642 goto invalid_return;
2645 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2650 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2658 GST_OBJECT_LOCK (element);
2659 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2660 g_critical ("%s: unknown return value %d from a state change function",
2661 GST_ELEMENT_NAME (element), ret);
2663 /* we are in error now */
2664 ret = GST_STATE_CHANGE_FAILURE;
2665 GST_STATE_RETURN (element) = ret;
2666 GST_OBJECT_UNLOCK (element);
2672 /* gst_iterator_fold functions for pads_activate
2673 * Stop the iterator if activating one pad failed. */
2675 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2677 GstPad *pad = g_value_get_object (vpad);
2678 gboolean cont = TRUE;
2680 if (!(cont = gst_pad_set_active (pad, *active)))
2681 g_value_set_boolean (ret, FALSE);
2686 /* returns false on error or early cutout of the fold, true if all
2687 * pads in @iter were (de)activated successfully. */
2689 iterator_activate_fold_with_resync (GstIterator * iter,
2690 GstIteratorFoldFunction func, gpointer user_data)
2692 GstIteratorResult ires;
2695 /* no need to unset this later, it's just a boolean */
2696 g_value_init (&ret, G_TYPE_BOOLEAN);
2697 g_value_set_boolean (&ret, TRUE);
2700 ires = gst_iterator_fold (iter, func, &ret, user_data);
2702 case GST_ITERATOR_RESYNC:
2703 /* need to reset the result again */
2704 g_value_set_boolean (&ret, TRUE);
2705 gst_iterator_resync (iter);
2707 case GST_ITERATOR_DONE:
2708 /* all pads iterated, return collected value */
2711 /* iterator returned _ERROR or premature end with _OK,
2712 * mark an error and exit */
2713 g_value_set_boolean (&ret, FALSE);
2718 /* return collected value */
2719 return g_value_get_boolean (&ret);
2722 /* is called with STATE_LOCK
2724 * Pads are activated from source pads to sinkpads.
2727 gst_element_pads_activate (GstElement * element, gboolean active)
2732 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2733 "pads_activate with active %d", active);
2735 iter = gst_element_iterate_src_pads (element);
2737 iterator_activate_fold_with_resync (iter,
2738 (GstIteratorFoldFunction) activate_pads, &active);
2739 gst_iterator_free (iter);
2740 if (G_UNLIKELY (!res))
2743 iter = gst_element_iterate_sink_pads (element);
2745 iterator_activate_fold_with_resync (iter,
2746 (GstIteratorFoldFunction) activate_pads, &active);
2747 gst_iterator_free (iter);
2748 if (G_UNLIKELY (!res))
2751 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2752 "pads_activate successful");
2759 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2760 "source pads_activate failed");
2765 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2766 "sink pads_activate failed");
2771 /* is called with STATE_LOCK */
2772 static GstStateChangeReturn
2773 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2775 GstState state, next;
2776 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2778 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2780 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2781 next = GST_STATE_TRANSITION_NEXT (transition);
2783 /* if the element already is in the given state, we just return success */
2784 if (next == GST_STATE_VOID_PENDING || state == next)
2787 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2788 "default handler tries setting state from %s to %s (%04x)",
2789 gst_element_state_get_name (state),
2790 gst_element_state_get_name (next), transition);
2792 switch (transition) {
2793 case GST_STATE_CHANGE_NULL_TO_READY:
2795 case GST_STATE_CHANGE_READY_TO_PAUSED:
2796 if (!gst_element_pads_activate (element, TRUE)) {
2797 result = GST_STATE_CHANGE_FAILURE;
2800 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2802 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2804 case GST_STATE_CHANGE_PAUSED_TO_READY:
2805 case GST_STATE_CHANGE_READY_TO_NULL:
2806 /* deactivate pads in both cases, since they are activated on
2807 ready->paused but the element might not have made it to paused */
2808 if (!gst_element_pads_activate (element, FALSE)) {
2809 result = GST_STATE_CHANGE_FAILURE;
2813 /* this will catch real but unhandled state changes;
2814 * can only be caused by:
2815 * - a new state was added
2816 * - somehow the element was asked to jump across an intermediate state
2818 g_warning ("Unhandled state change from %s to %s",
2819 gst_element_state_get_name (state),
2820 gst_element_state_get_name (next));
2827 GST_OBJECT_LOCK (element);
2828 result = GST_STATE_RETURN (element);
2829 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2830 "element is already in the %s state",
2831 gst_element_state_get_name (state));
2832 GST_OBJECT_UNLOCK (element);
2839 * gst_element_get_factory:
2840 * @element: a #GstElement to request the element factory of.
2842 * Retrieves the factory that was used to create this element.
2844 * Returns: (transfer none): the #GstElementFactory used for creating this
2845 * element. no refcounting is needed.
2848 gst_element_get_factory (GstElement * element)
2850 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2852 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2856 gst_element_dispose (GObject * object)
2858 GstElement *element = GST_ELEMENT_CAST (object);
2862 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2864 if (GST_STATE (element) != GST_STATE_NULL)
2867 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2868 "removing %d pads", g_list_length (element->pads));
2869 /* first we break all our links with the outside */
2870 while (element->pads && element->pads->data) {
2871 /* don't call _remove_pad with NULL */
2872 gst_element_remove_pad (element, GST_PAD_CAST (element->pads->data));
2874 if (G_UNLIKELY (element->pads != NULL)) {
2875 g_critical ("could not remove pads from element %s",
2876 GST_STR_NULL (GST_OBJECT_NAME (object)));
2879 GST_OBJECT_LOCK (element);
2880 clock_p = &element->clock;
2881 bus_p = &element->bus;
2882 gst_object_replace ((GstObject **) clock_p, NULL);
2883 gst_object_replace ((GstObject **) bus_p, NULL);
2884 GST_OBJECT_UNLOCK (element);
2886 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2888 G_OBJECT_CLASS (parent_class)->dispose (object);
2897 is_locked = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
2899 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2901 "You need to explicitly set elements to the NULL state before\n"
2902 "dropping the final reference, to allow them to clean up.\n"
2903 "This problem may also be caused by a refcounting bug in the\n"
2904 "application or some element.\n",
2905 GST_OBJECT_NAME (element),
2906 gst_element_state_get_name (GST_STATE (element)),
2907 is_locked ? " (locked)" : "");
2913 gst_element_finalize (GObject * object)
2915 GstElement *element = GST_ELEMENT_CAST (object);
2917 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2919 g_cond_free (element->state_cond);
2920 g_static_rec_mutex_free (&element->state_lock);
2922 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2924 G_OBJECT_CLASS (parent_class)->finalize (object);
2928 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2932 g_return_if_fail (GST_IS_ELEMENT (element));
2934 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2936 GST_OBJECT_LOCK (element);
2937 bus_p = &GST_ELEMENT_BUS (element);
2938 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
2939 GST_OBJECT_UNLOCK (element);
2943 * gst_element_set_bus:
2944 * @element: a #GstElement to set the bus of.
2945 * @bus: (transfer none): the #GstBus to set.
2947 * Sets the bus of the element. Increases the refcount on the bus.
2948 * For internal use only, unless you're testing elements.
2953 gst_element_set_bus (GstElement * element, GstBus * bus)
2955 GstElementClass *oclass;
2957 g_return_if_fail (GST_IS_ELEMENT (element));
2959 oclass = GST_ELEMENT_GET_CLASS (element);
2961 if (oclass->set_bus)
2962 oclass->set_bus (element, bus);
2966 * gst_element_get_bus:
2967 * @element: a #GstElement to get the bus of.
2969 * Returns the bus of the element. Note that only a #GstPipeline will provide a
2970 * bus for the application.
2972 * Returns: (transfer full): the element's #GstBus. unref after usage.
2977 gst_element_get_bus (GstElement * element)
2979 GstBus *result = NULL;
2981 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
2983 GST_OBJECT_LOCK (element);
2984 if ((result = GST_ELEMENT_BUS (element)))
2985 gst_object_ref (result);
2986 GST_OBJECT_UNLOCK (element);
2988 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,