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., 51 Franklin St, Fifth Floor,
20 * Boston, MA 02110-1301, 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 * Elements can 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.
47 * An iterator of all pads can be retrieved with gst_element_iterate_pads().
49 * Elements can be linked through their pads.
50 * If the link is straightforward, use the gst_element_link()
51 * convenience function to link two elements, or gst_element_link_many()
52 * for more elements in a row.
53 * Use gst_element_link_filtered() to link two elements constrained by
54 * a specified set of #GstCaps.
55 * For finer control, use gst_element_link_pads() and
56 * gst_element_link_pads_filtered() to specify the pads to link on
57 * each element by name.
59 * Each element has a state (see #GstState). You can get and set the state
60 * of an element with gst_element_get_state() and gst_element_set_state().
61 * Setting a state triggers a #GstStateChange. To get a string representation
62 * of a #GstState, use gst_element_state_get_name().
64 * You can get and set a #GstClock on an element using gst_element_get_clock()
65 * and gst_element_set_clock().
66 * Some elements can provide a clock for the pipeline if
67 * the #GST_ELEMENT_FLAG_PROVIDE_CLOCK flag is set. With the
68 * gst_element_provide_clock() method one can retrieve the clock provided by
70 * Not all elements require a clock to operate correctly. If the
71 * #GST_ELEMENT_FLAG_REQUIRE_CLOCK() flag is set, a clock should be set on the
72 * element with gst_element_set_clock().
74 * Note that clock selection and distribution is normally handled by the
75 * toplevel #GstPipeline so the clock functions are only to be used in very
76 * specific situations.
79 #include "gst_private.h"
82 #include <gobject/gvaluecollector.h>
84 #include "gstelement.h"
85 #include "gstelementmetadata.h"
86 #include "gstenumtypes.h"
94 #include "gst-i18n-lib.h"
95 #include "glib-compat-private.h"
97 #ifndef GST_DISABLE_GST_DEBUG
98 #include "printf/printf.h"
101 /* Element signals and args */
117 static void gst_element_class_init (GstElementClass * klass);
118 static void gst_element_init (GstElement * element);
119 static void gst_element_base_class_init (gpointer g_class);
120 static void gst_element_base_class_finalize (gpointer g_class);
122 static void gst_element_dispose (GObject * object);
123 static void gst_element_finalize (GObject * object);
125 static GstStateChangeReturn gst_element_change_state_func (GstElement * element,
126 GstStateChange transition);
127 static GstStateChangeReturn gst_element_get_state_func (GstElement * element,
128 GstState * state, GstState * pending, GstClockTime timeout);
129 static GstStateChangeReturn gst_element_set_state_func (GstElement * element,
131 static gboolean gst_element_set_clock_func (GstElement * element,
133 static void gst_element_set_bus_func (GstElement * element, GstBus * bus);
134 static gboolean gst_element_post_message_default (GstElement * element,
135 GstMessage * message);
137 static gboolean gst_element_default_send_event (GstElement * element,
139 static gboolean gst_element_default_query (GstElement * element,
142 static GstPadTemplate
143 * gst_element_class_get_request_pad_template (GstElementClass *
144 element_class, const gchar * name);
146 static GstObjectClass *parent_class = NULL;
147 static guint gst_element_signals[LAST_SIGNAL] = { 0 };
149 /* this is used in gstelementfactory.c:gst_element_register() */
150 GQuark __gst_elementclass_factory = 0;
153 gst_element_get_type (void)
155 static volatile gsize gst_element_type = 0;
157 if (g_once_init_enter (&gst_element_type)) {
159 static const GTypeInfo element_info = {
160 sizeof (GstElementClass),
161 gst_element_base_class_init,
162 gst_element_base_class_finalize,
163 (GClassInitFunc) gst_element_class_init,
168 (GInstanceInitFunc) gst_element_init,
172 _type = g_type_register_static (GST_TYPE_OBJECT, "GstElement",
173 &element_info, G_TYPE_FLAG_ABSTRACT);
175 __gst_elementclass_factory =
176 g_quark_from_static_string ("GST_ELEMENTCLASS_FACTORY");
177 g_once_init_leave (&gst_element_type, _type);
179 return gst_element_type;
183 gst_element_class_init (GstElementClass * klass)
185 GObjectClass *gobject_class;
187 gobject_class = (GObjectClass *) klass;
189 parent_class = g_type_class_peek_parent (klass);
192 * GstElement::pad-added:
193 * @gstelement: the object which received the signal
194 * @new_pad: the pad that has been added
196 * a new #GstPad has been added to the element. Note that this signal will
197 * usually be emitted from the context of the streaming thread. Also keep in
198 * mind that if you add new elements to the pipeline in the signal handler
199 * you will need to set them to the desired target state with
200 * gst_element_set_state() or gst_element_sync_state_with_parent().
202 gst_element_signals[PAD_ADDED] =
203 g_signal_new ("pad-added", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
204 G_STRUCT_OFFSET (GstElementClass, pad_added), NULL, NULL,
205 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
207 * GstElement::pad-removed:
208 * @gstelement: the object which received the signal
209 * @old_pad: the pad that has been removed
211 * a #GstPad has been removed from the element
213 gst_element_signals[PAD_REMOVED] =
214 g_signal_new ("pad-removed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
215 G_STRUCT_OFFSET (GstElementClass, pad_removed), NULL, NULL,
216 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
218 * GstElement::no-more-pads:
219 * @gstelement: the object which received the signal
221 * This signals that the element will not generate more dynamic pads.
222 * Note that this signal will usually be emitted from the context of
223 * the streaming thread.
225 gst_element_signals[NO_MORE_PADS] =
226 g_signal_new ("no-more-pads", G_TYPE_FROM_CLASS (klass),
227 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstElementClass, no_more_pads), NULL,
228 NULL, g_cclosure_marshal_generic, G_TYPE_NONE, 0);
230 gobject_class->dispose = gst_element_dispose;
231 gobject_class->finalize = gst_element_finalize;
233 klass->change_state = GST_DEBUG_FUNCPTR (gst_element_change_state_func);
234 klass->set_state = GST_DEBUG_FUNCPTR (gst_element_set_state_func);
235 klass->get_state = GST_DEBUG_FUNCPTR (gst_element_get_state_func);
236 klass->set_clock = GST_DEBUG_FUNCPTR (gst_element_set_clock_func);
237 klass->set_bus = GST_DEBUG_FUNCPTR (gst_element_set_bus_func);
238 klass->query = GST_DEBUG_FUNCPTR (gst_element_default_query);
239 klass->send_event = GST_DEBUG_FUNCPTR (gst_element_default_send_event);
240 klass->numpadtemplates = 0;
241 klass->post_message = GST_DEBUG_FUNCPTR (gst_element_post_message_default);
243 klass->elementfactory = NULL;
247 gst_element_base_class_init (gpointer g_class)
249 GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
250 GList *node, *padtemplates;
252 /* Copy the element details here so elements can inherit the
253 * details from their base class and classes only need to set
254 * the details in class_init instead of base_init */
255 element_class->metadata =
256 element_class->metadata ? gst_structure_copy (element_class->metadata) :
257 gst_structure_new_empty ("metadata");
259 /* Copy the pad templates so elements inherit them
260 * from their base class but elements can add pad templates in class_init
261 * instead of base_init.
263 padtemplates = g_list_copy (element_class->padtemplates);
264 for (node = padtemplates; node != NULL; node = node->next) {
265 GstPadTemplate *tmpl = (GstPadTemplate *) node->data;
266 gst_object_ref (tmpl);
268 element_class->padtemplates = padtemplates;
270 /* set the factory, see gst_element_register() */
271 element_class->elementfactory =
272 g_type_get_qdata (G_TYPE_FROM_CLASS (element_class),
273 __gst_elementclass_factory);
274 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "type %s : factory %p",
275 G_OBJECT_CLASS_NAME (element_class), element_class->elementfactory);
279 gst_element_base_class_finalize (gpointer g_class)
281 GstElementClass *klass = GST_ELEMENT_CLASS (g_class);
283 g_list_foreach (klass->padtemplates, (GFunc) gst_object_unref, NULL);
284 g_list_free (klass->padtemplates);
286 gst_structure_free (klass->metadata);
290 gst_element_init (GstElement * element)
292 GST_STATE (element) = GST_STATE_NULL;
293 GST_STATE_TARGET (element) = GST_STATE_NULL;
294 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
295 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
296 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
298 g_rec_mutex_init (&element->state_lock);
299 g_cond_init (&element->state_cond);
303 * gst_element_release_request_pad:
304 * @element: a #GstElement to release the request pad of.
305 * @pad: the #GstPad to release.
307 * Makes the element free the previously requested pad as obtained
308 * with gst_element_request_pad().
310 * This does not unref the pad. If the pad was created by using
311 * gst_element_request_pad(), gst_element_release_request_pad() needs to be
312 * followed by gst_object_unref() to free the @pad.
317 gst_element_release_request_pad (GstElement * element, GstPad * pad)
319 GstElementClass *oclass;
321 g_return_if_fail (GST_IS_ELEMENT (element));
322 g_return_if_fail (GST_IS_PAD (pad));
323 g_return_if_fail (GST_PAD_PAD_TEMPLATE (pad) == NULL ||
324 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad)) ==
327 oclass = GST_ELEMENT_GET_CLASS (element);
329 /* if the element implements a custom release function we call that, else we
330 * simply remove the pad from the element */
331 if (oclass->release_pad)
332 oclass->release_pad (element, pad);
334 gst_element_remove_pad (element, pad);
338 * gst_element_provide_clock:
339 * @element: a #GstElement to query
341 * Get the clock provided by the given element.
342 * <note>An element is only required to provide a clock in the PAUSED
343 * state. Some elements can provide a clock in other states.</note>
345 * Returns: (transfer full) (nullable): the GstClock provided by the
346 * element or %NULL if no clock could be provided. Unref after usage.
351 gst_element_provide_clock (GstElement * element)
353 GstClock *result = NULL;
354 GstElementClass *oclass;
356 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
358 oclass = GST_ELEMENT_GET_CLASS (element);
360 if (oclass->provide_clock)
361 result = oclass->provide_clock (element);
367 gst_element_set_clock_func (GstElement * element, GstClock * clock)
371 GST_OBJECT_LOCK (element);
372 clock_p = &element->clock;
373 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
374 GST_OBJECT_UNLOCK (element);
380 * gst_element_set_clock:
381 * @element: a #GstElement to set the clock for.
382 * @clock: the #GstClock to set for the element.
384 * Sets the clock for the element. This function increases the
385 * refcount on the clock. Any previously set clock on the object
388 * Returns: %TRUE if the element accepted the clock. An element can refuse a
389 * clock when it, for example, is not able to slave its internal clock to the
390 * @clock or when it requires a specific clock to operate.
395 gst_element_set_clock (GstElement * element, GstClock * clock)
397 GstElementClass *oclass;
398 gboolean res = FALSE;
400 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
401 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
403 oclass = GST_ELEMENT_GET_CLASS (element);
405 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
407 if (oclass->set_clock)
408 res = oclass->set_clock (element, clock);
414 * gst_element_get_clock:
415 * @element: a #GstElement to get the clock of.
417 * Gets the currently configured clock of the element. This is the clock as was
418 * last set with gst_element_set_clock().
420 * Elements in a pipeline will only have their clock set when the
421 * pipeline is in the PLAYING state.
423 * Returns: (transfer full): the #GstClock of the element. unref after usage.
428 gst_element_get_clock (GstElement * element)
432 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
434 GST_OBJECT_LOCK (element);
435 if ((result = element->clock))
436 gst_object_ref (result);
437 GST_OBJECT_UNLOCK (element);
443 * gst_element_set_base_time:
444 * @element: a #GstElement.
445 * @time: the base time to set.
447 * Set the base time of an element. See gst_element_get_base_time().
452 gst_element_set_base_time (GstElement * element, GstClockTime time)
456 g_return_if_fail (GST_IS_ELEMENT (element));
458 GST_OBJECT_LOCK (element);
459 old = element->base_time;
460 element->base_time = time;
461 GST_OBJECT_UNLOCK (element);
463 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
464 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
465 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
469 * gst_element_get_base_time:
470 * @element: a #GstElement.
472 * Returns the base time of the element. The base time is the
473 * absolute time of the clock when this element was last put to
474 * PLAYING. Subtracting the base time from the clock time gives
475 * the running time of the element.
477 * Returns: the base time of the element.
482 gst_element_get_base_time (GstElement * element)
486 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
488 GST_OBJECT_LOCK (element);
489 result = element->base_time;
490 GST_OBJECT_UNLOCK (element);
496 * gst_element_set_start_time:
497 * @element: a #GstElement.
498 * @time: the base time to set.
500 * Set the start time of an element. The start time of the element is the
501 * running time of the element when it last went to the PAUSED state. In READY
502 * or after a flushing seek, it is set to 0.
504 * Toplevel elements like #GstPipeline will manage the start_time and
505 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
506 * on such a toplevel element will disable the distribution of the base_time to
507 * the children and can be useful if the application manages the base_time
508 * itself, for example if you want to synchronize capture from multiple
509 * pipelines, and you can also ensure that the pipelines have the same clock.
514 gst_element_set_start_time (GstElement * element, GstClockTime time)
518 g_return_if_fail (GST_IS_ELEMENT (element));
520 GST_OBJECT_LOCK (element);
521 old = GST_ELEMENT_START_TIME (element);
522 GST_ELEMENT_START_TIME (element) = time;
523 GST_OBJECT_UNLOCK (element);
525 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
526 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
527 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
531 * gst_element_get_start_time:
532 * @element: a #GstElement.
534 * Returns the start time of the element. The start time is the
535 * running time of the clock when this element was last put to PAUSED.
537 * Usually the start_time is managed by a toplevel element such as
542 * Returns: the start time of the element.
545 gst_element_get_start_time (GstElement * element)
549 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
551 GST_OBJECT_LOCK (element);
552 result = GST_ELEMENT_START_TIME (element);
553 GST_OBJECT_UNLOCK (element);
560 * gst_element_set_index:
561 * @element: a #GstElement.
562 * @index: (transfer none): a #GstIndex.
564 * Set @index on the element. The refcount of the index
565 * will be increased, any previously set index is unreffed.
570 gst_element_set_index (GstElement * element, GstIndex * index)
572 GstElementClass *oclass;
574 g_return_if_fail (GST_IS_ELEMENT (element));
575 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
577 oclass = GST_ELEMENT_GET_CLASS (element);
579 if (oclass->set_index)
580 oclass->set_index (element, index);
584 * gst_element_get_index:
585 * @element: a #GstElement.
587 * Gets the index from the element.
589 * Returns: (transfer full) (nullable): a #GstIndex or %NULL when no
590 * index was set on the element. unref after usage.
595 gst_element_get_index (GstElement * element)
597 GstElementClass *oclass;
598 GstIndex *result = NULL;
600 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
602 oclass = GST_ELEMENT_GET_CLASS (element);
604 if (oclass->get_index)
605 result = oclass->get_index (element);
612 * gst_element_add_pad:
613 * @element: a #GstElement to add the pad to.
614 * @pad: (transfer full): the #GstPad to add to the element.
616 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
617 * see gst_object_set_parent() for refcounting information.
619 * Pads are not automatically activated so elements should perform the needed
620 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
621 * state. See gst_pad_set_active() for more information about activating pads.
623 * The pad and the element should be unlocked when calling this function.
625 * This function will emit the #GstElement::pad-added signal on the element.
627 * Returns: %TRUE if the pad could be added. This function can fail when
628 * a pad with the same name already existed or the pad already had another
634 gst_element_add_pad (GstElement * element, GstPad * pad)
639 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
640 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
643 g_object_set (G_OBJECT (pad), "family-id",
644 (int) (GST_OBJECT_CAST (element)->family_id), NULL);
647 /* locking pad to look at the name */
648 GST_OBJECT_LOCK (pad);
649 pad_name = g_strdup (GST_PAD_NAME (pad));
650 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
651 GST_STR_NULL (pad_name));
652 flushing = GST_PAD_IS_FLUSHING (pad);
653 GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_NEED_PARENT);
654 GST_OBJECT_UNLOCK (pad);
656 /* then check to see if there's already a pad by that name here */
657 GST_OBJECT_LOCK (element);
658 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
661 /* try to set the pad's parent */
662 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
663 GST_OBJECT_CAST (element))))
666 /* check for flushing pads */
667 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
668 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
669 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
670 "use gst_pad_set_active(pad,TRUE) before adding it.",
671 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
673 GST_OBJECT_LOCK (pad);
674 GST_PAD_UNSET_FLUSHING (pad);
675 GST_OBJECT_UNLOCK (pad);
680 /* add it to the list */
681 switch (gst_pad_get_direction (pad)) {
683 element->srcpads = g_list_append (element->srcpads, pad);
684 element->numsrcpads++;
687 element->sinkpads = g_list_append (element->sinkpads, pad);
688 element->numsinkpads++;
693 element->pads = g_list_append (element->pads, pad);
695 element->pads_cookie++;
696 GST_OBJECT_UNLOCK (element);
698 /* emit the PAD_ADDED signal */
699 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
706 g_critical ("Padname %s is not unique in element %s, not adding",
707 pad_name, GST_ELEMENT_NAME (element));
708 GST_OBJECT_UNLOCK (element);
715 ("Pad %s already has parent when trying to add to element %s",
716 pad_name, GST_ELEMENT_NAME (element));
717 GST_OBJECT_UNLOCK (element);
723 GST_OBJECT_LOCK (pad);
725 ("Trying to add pad %s to element %s, but it has no direction",
726 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
727 GST_OBJECT_UNLOCK (pad);
728 GST_OBJECT_UNLOCK (element);
734 * gst_element_remove_pad:
735 * @element: a #GstElement to remove pad from.
736 * @pad: (transfer full): the #GstPad to remove from the element.
738 * Removes @pad from @element. @pad will be destroyed if it has not been
739 * referenced elsewhere using gst_object_unparent().
741 * This function is used by plugin developers and should not be used
742 * by applications. Pads that were dynamically requested from elements
743 * with gst_element_request_pad() should be released with the
744 * gst_element_release_request_pad() function instead.
746 * Pads are not automatically deactivated so elements should perform the needed
747 * steps to deactivate the pad in case this pad is removed in the PAUSED or
748 * PLAYING state. See gst_pad_set_active() for more information about
751 * The pad and the element should be unlocked when calling this function.
753 * This function will emit the #GstElement::pad-removed signal on the element.
755 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
756 * pad does not belong to the provided element.
761 gst_element_remove_pad (GstElement * element, GstPad * pad)
765 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
766 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
768 /* locking pad to look at the name and parent */
769 GST_OBJECT_LOCK (pad);
770 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
771 GST_STR_NULL (GST_PAD_NAME (pad)));
773 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
775 GST_OBJECT_UNLOCK (pad);
778 if ((peer = gst_pad_get_peer (pad))) {
779 /* window for MT unsafeness, someone else could unlink here
780 * and then we call unlink with wrong pads. The unlink
781 * function would catch this and safely return failed. */
782 if (GST_PAD_IS_SRC (pad))
783 gst_pad_unlink (pad, peer);
785 gst_pad_unlink (peer, pad);
787 gst_object_unref (peer);
790 GST_OBJECT_LOCK (element);
791 /* remove it from the list */
792 switch (gst_pad_get_direction (pad)) {
794 element->srcpads = g_list_remove (element->srcpads, pad);
795 element->numsrcpads--;
798 element->sinkpads = g_list_remove (element->sinkpads, pad);
799 element->numsinkpads--;
802 g_critical ("Removing pad without direction???");
805 element->pads = g_list_remove (element->pads, pad);
807 element->pads_cookie++;
808 GST_OBJECT_UNLOCK (element);
810 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
811 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
813 gst_object_unparent (GST_OBJECT_CAST (pad));
820 /* locking order is element > pad */
821 GST_OBJECT_UNLOCK (pad);
823 GST_OBJECT_LOCK (element);
824 GST_OBJECT_LOCK (pad);
825 g_critical ("Padname %s:%s does not belong to element %s when removing",
826 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
827 GST_OBJECT_UNLOCK (pad);
828 GST_OBJECT_UNLOCK (element);
834 * gst_element_no_more_pads:
835 * @element: a #GstElement
837 * Use this function to signal that the element does not expect any more pads
838 * to show up in the current pipeline. This function should be called whenever
839 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
840 * pad templates use this in combination with autopluggers to figure out that
841 * the element is done initializing its pads.
843 * This function emits the #GstElement::no-more-pads signal.
848 gst_element_no_more_pads (GstElement * element)
850 g_return_if_fail (GST_IS_ELEMENT (element));
852 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
856 pad_compare_name (GstPad * pad1, const gchar * name)
860 GST_OBJECT_LOCK (pad1);
861 result = strcmp (GST_PAD_NAME (pad1), name);
862 GST_OBJECT_UNLOCK (pad1);
868 * gst_element_get_static_pad:
869 * @element: a #GstElement to find a static pad of.
870 * @name: the name of the static #GstPad to retrieve.
872 * Retrieves a pad from @element by name. This version only retrieves
873 * already-existing (i.e. 'static') pads.
875 * Returns: (transfer full) (nullable): the requested #GstPad if
876 * found, otherwise %NULL. unref after usage.
881 gst_element_get_static_pad (GstElement * element, const gchar * name)
884 GstPad *result = NULL;
886 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
887 g_return_val_if_fail (name != NULL, NULL);
889 GST_OBJECT_LOCK (element);
891 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
893 result = GST_PAD_CAST (find->data);
894 gst_object_ref (result);
897 if (result == NULL) {
898 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
899 name, GST_ELEMENT_NAME (element));
901 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
902 GST_ELEMENT_NAME (element), name);
904 GST_OBJECT_UNLOCK (element);
910 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
911 const gchar * name, const GstCaps * caps)
913 GstPad *newpad = NULL;
914 GstElementClass *oclass;
916 oclass = GST_ELEMENT_GET_CLASS (element);
918 #ifndef G_DISABLE_CHECKS
919 /* Some sanity checking here */
923 /* Is this the template name? */
924 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
925 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
927 const gchar *str, *data;
930 /* Otherwise check if it's a valid name for the name template */
931 str = strchr (templ->name_template, '%');
932 g_return_val_if_fail (str != NULL, NULL);
933 g_return_val_if_fail (strncmp (templ->name_template, name,
934 str - templ->name_template) == 0, NULL);
935 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
937 data = name + (str - templ->name_template);
939 /* Can either be %s or %d or %u, do sanity checking for %d */
940 if (*(str + 1) == 'd') {
944 tmp = g_ascii_strtoll (data, &endptr, 10);
945 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
946 && *endptr == '\0', NULL);
947 } else if (*(str + 1) == 'u') {
951 tmp = g_ascii_strtoull (data, &endptr, 10);
952 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
956 pad = gst_element_get_static_pad (element, name);
958 gst_object_unref (pad);
959 /* FIXME 2.0: Change this to g_return_val_if_fail() */
960 g_critical ("Element %s already has a pad named %s, the behaviour of "
961 " gst_element_get_request_pad() for existing pads is undefined!",
962 GST_ELEMENT_NAME (element), name);
967 if (oclass->request_new_pad)
968 newpad = (oclass->request_new_pad) (element, templ, name, caps);
971 gst_object_ref (newpad);
977 * gst_element_get_request_pad:
978 * @element: a #GstElement to find a request pad of.
979 * @name: the name of the request #GstPad to retrieve.
981 * Retrieves a pad from the element by name (e.g. "src_\%d"). This version only
982 * retrieves request pads. The pad should be released with
983 * gst_element_release_request_pad().
985 * This method is slower than manually getting the pad template and calling
986 * gst_element_request_pad() if the pads should have a specific name (e.g.
987 * @name is "src_1" instead of "src_\%u").
989 * Returns: (transfer full) (nullable): requested #GstPad if found,
990 * otherwise %NULL. Release after usage.
993 gst_element_get_request_pad (GstElement * element, const gchar * name)
995 GstPadTemplate *templ = NULL;
997 const gchar *req_name = NULL;
998 gboolean templ_found = FALSE;
1001 gchar *str, *endptr = NULL;
1002 GstElementClass *class;
1004 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1005 g_return_val_if_fail (name != NULL, NULL);
1007 class = GST_ELEMENT_GET_CLASS (element);
1009 /* if the name contains a %, we assume it's the complete template name. Get
1010 * the template and try to get a pad */
1011 if (strstr (name, "%")) {
1012 templ = gst_element_class_get_request_pad_template (class, name);
1017 /* there is no % in the name, try to find a matching template */
1018 list = class->padtemplates;
1019 while (!templ_found && list) {
1020 templ = (GstPadTemplate *) list->data;
1021 if (templ->presence == GST_PAD_REQUEST) {
1022 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1023 templ->name_template);
1024 /* see if we find an exact match */
1025 if (strcmp (name, templ->name_template) == 0) {
1030 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1031 and %d and %u, occurring at the end of the name_template, are the only
1033 else if ((str = strchr (templ->name_template, '%'))
1034 && strncmp (templ->name_template, name,
1035 str - templ->name_template) == 0
1036 && strlen (name) > str - templ->name_template) {
1037 data = name + (str - templ->name_template);
1038 if (*(str + 1) == 'd') {
1042 tmp = strtol (data, &endptr, 10);
1043 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1049 } else if (*(str + 1) == 'u') {
1053 tmp = strtoul (data, &endptr, 10);
1054 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1074 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1080 * gst_element_request_pad: (virtual request_new_pad)
1081 * @element: a #GstElement to find a request pad of.
1082 * @templ: a #GstPadTemplate of which we want a pad of.
1083 * @name: (transfer none) (allow-none): the name of the request #GstPad
1084 * to retrieve. Can be %NULL.
1085 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1086 * request. Can be %NULL.
1088 * Retrieves a request pad from the element according to the provided template.
1089 * Pad templates can be looked up using
1090 * gst_element_factory_get_static_pad_templates().
1092 * The pad should be released with gst_element_release_request_pad().
1094 * Returns: (transfer full) (nullable): requested #GstPad if found,
1095 * otherwise %NULL. Release after usage.
1098 gst_element_request_pad (GstElement * element,
1099 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1101 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1102 g_return_val_if_fail (templ != NULL, NULL);
1103 g_return_val_if_fail (templ->presence == GST_PAD_REQUEST, NULL);
1105 return _gst_element_request_pad (element, templ, name, caps);
1108 static GstIterator *
1109 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1111 GstIterator *result;
1113 GST_OBJECT_LOCK (element);
1114 result = gst_iterator_new_list (GST_TYPE_PAD,
1115 GST_OBJECT_GET_LOCK (element),
1116 &element->pads_cookie, padlist, (GObject *) element, NULL);
1117 GST_OBJECT_UNLOCK (element);
1123 * gst_element_iterate_pads:
1124 * @element: a #GstElement to iterate pads of.
1126 * Retrieves an iterator of @element's pads. The iterator should
1127 * be freed after usage. Also more specialized iterators exists such as
1128 * gst_element_iterate_src_pads() or gst_element_iterate_sink_pads().
1130 * The order of pads returned by the iterator will be the order in which
1131 * the pads were added to the element.
1133 * Returns: (transfer full): the #GstIterator of #GstPad.
1138 gst_element_iterate_pads (GstElement * element)
1140 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1142 return gst_element_iterate_pad_list (element, &element->pads);
1146 * gst_element_iterate_src_pads:
1147 * @element: a #GstElement.
1149 * Retrieves an iterator of @element's source pads.
1151 * The order of pads returned by the iterator will be the order in which
1152 * the pads were added to the element.
1154 * Returns: (transfer full): the #GstIterator of #GstPad.
1159 gst_element_iterate_src_pads (GstElement * element)
1161 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1163 return gst_element_iterate_pad_list (element, &element->srcpads);
1167 * gst_element_iterate_sink_pads:
1168 * @element: a #GstElement.
1170 * Retrieves an iterator of @element's sink pads.
1172 * The order of pads returned by the iterator will be the order in which
1173 * the pads were added to the element.
1175 * Returns: (transfer full): the #GstIterator of #GstPad.
1180 gst_element_iterate_sink_pads (GstElement * element)
1182 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1184 return gst_element_iterate_pad_list (element, &element->sinkpads);
1188 * gst_element_class_add_pad_template:
1189 * @klass: the #GstElementClass to add the pad template to.
1190 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1192 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1193 * functions of classes. If a pad template with the same name as an already
1194 * existing one is added the old one is replaced by the new one.
1198 gst_element_class_add_pad_template (GstElementClass * klass,
1199 GstPadTemplate * templ)
1201 GList *template_list = klass->padtemplates;
1203 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1204 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1206 /* If we already have a pad template with the same name replace the
1208 while (template_list) {
1209 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1211 /* Found pad with the same name, replace and return */
1212 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1213 gst_object_unref (padtempl);
1214 template_list->data = templ;
1217 template_list = g_list_next (template_list);
1220 /* Take ownership of the floating ref */
1221 gst_object_ref_sink (templ);
1223 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1224 klass->numpadtemplates++;
1228 * gst_element_class_add_metadata:
1229 * @klass: class to set metadata for
1230 * @key: the key to set
1231 * @value: the value to set
1233 * Set @key with @value as metadata in @klass.
1236 gst_element_class_add_metadata (GstElementClass * klass,
1237 const gchar * key, const gchar * value)
1239 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1240 g_return_if_fail (key != NULL);
1241 g_return_if_fail (value != NULL);
1243 gst_structure_set ((GstStructure *) klass->metadata,
1244 key, G_TYPE_STRING, value, NULL);
1248 * gst_element_class_add_static_metadata:
1249 * @klass: class to set metadata for
1250 * @key: the key to set
1251 * @value: the value to set
1253 * Set @key with @value as metadata in @klass.
1255 * Same as gst_element_class_add_metadata(), but @value must be a static string
1256 * or an inlined string, as it will not be copied. (GStreamer plugins will
1257 * be made resident once loaded, so this function can be used even from
1258 * dynamically loaded plugins.)
1261 gst_element_class_add_static_metadata (GstElementClass * klass,
1262 const gchar * key, const gchar * value)
1264 GValue val = G_VALUE_INIT;
1266 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1267 g_return_if_fail (key != NULL);
1268 g_return_if_fail (value != NULL);
1270 g_value_init (&val, G_TYPE_STRING);
1271 g_value_set_static_string (&val, value);
1272 gst_structure_take_value ((GstStructure *) klass->metadata, key, &val);
1276 * gst_element_class_set_metadata:
1277 * @klass: class to set metadata for
1278 * @longname: The long English name of the element. E.g. "File Sink"
1279 * @classification: String describing the type of element, as an unordered list
1280 * separated with slashes ('/'). See draft-klass.txt of the design docs
1281 * for more details and common types. E.g: "Sink/File"
1282 * @description: Sentence describing the purpose of the element.
1283 * E.g: "Write stream to a file"
1284 * @author: Name and contact details of the author(s). Use \n to separate
1285 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1287 * Sets the detailed information for a #GstElementClass.
1288 * <note>This function is for use in _class_init functions only.</note>
1291 gst_element_class_set_metadata (GstElementClass * klass,
1292 const gchar * longname, const gchar * classification,
1293 const gchar * description, const gchar * author)
1295 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1296 g_return_if_fail (longname != NULL && *longname != '\0');
1297 g_return_if_fail (classification != NULL && *classification != '\0');
1298 g_return_if_fail (description != NULL && *description != '\0');
1299 g_return_if_fail (author != NULL && *author != '\0');
1301 gst_structure_id_set ((GstStructure *) klass->metadata,
1302 GST_QUARK (ELEMENT_METADATA_LONGNAME), G_TYPE_STRING, longname,
1303 GST_QUARK (ELEMENT_METADATA_KLASS), G_TYPE_STRING, classification,
1304 GST_QUARK (ELEMENT_METADATA_DESCRIPTION), G_TYPE_STRING, description,
1305 GST_QUARK (ELEMENT_METADATA_AUTHOR), G_TYPE_STRING, author, NULL);
1309 * gst_element_class_set_static_metadata:
1310 * @klass: class to set metadata for
1311 * @longname: The long English name of the element. E.g. "File Sink"
1312 * @classification: String describing the type of element, as an unordered list
1313 * separated with slashes ('/'). See draft-klass.txt of the design docs
1314 * for more details and common types. E.g: "Sink/File"
1315 * @description: Sentence describing the purpose of the element.
1316 * E.g: "Write stream to a file"
1317 * @author: Name and contact details of the author(s). Use \n to separate
1318 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1320 * Sets the detailed information for a #GstElementClass.
1321 * <note>This function is for use in _class_init functions only.</note>
1323 * Same as gst_element_class_set_metadata(), but @longname, @classification,
1324 * @description, and @author must be static strings or inlined strings, as
1325 * they will not be copied. (GStreamer plugins will be made resident once
1326 * loaded, so this function can be used even from dynamically loaded plugins.)
1329 gst_element_class_set_static_metadata (GstElementClass * klass,
1330 const gchar * longname, const gchar * classification,
1331 const gchar * description, const gchar * author)
1333 GstStructure *s = (GstStructure *) klass->metadata;
1334 GValue val = G_VALUE_INIT;
1336 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1337 g_return_if_fail (longname != NULL && *longname != '\0');
1338 g_return_if_fail (classification != NULL && *classification != '\0');
1339 g_return_if_fail (description != NULL && *description != '\0');
1340 g_return_if_fail (author != NULL && *author != '\0');
1342 g_value_init (&val, G_TYPE_STRING);
1344 g_value_set_static_string (&val, longname);
1345 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_LONGNAME), &val);
1347 g_value_set_static_string (&val, classification);
1348 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_KLASS), &val);
1350 g_value_set_static_string (&val, description);
1351 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_DESCRIPTION),
1354 g_value_set_static_string (&val, author);
1355 gst_structure_id_take_value (s, GST_QUARK (ELEMENT_METADATA_AUTHOR), &val);
1359 * gst_element_class_get_metadata:
1360 * @klass: class to get metadata for
1361 * @key: the key to get
1363 * Get metadata with @key in @klass.
1365 * Returns: the metadata for @key.
1368 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1370 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1371 g_return_val_if_fail (key != NULL, NULL);
1373 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1377 * gst_element_class_get_pad_template_list:
1378 * @element_class: a #GstElementClass to get pad templates of.
1380 * Retrieves a list of the pad templates associated with @element_class. The
1381 * list must not be modified by the calling code.
1382 * <note>If you use this function in the #GInstanceInitFunc of an object class
1383 * that has subclasses, make sure to pass the g_class parameter of the
1384 * #GInstanceInitFunc here.</note>
1386 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1390 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1392 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1394 return element_class->padtemplates;
1398 * gst_element_class_get_pad_template:
1399 * @element_class: a #GstElementClass to get the pad template of.
1400 * @name: the name of the #GstPadTemplate to get.
1402 * Retrieves a padtemplate from @element_class with the given name.
1403 * <note>If you use this function in the #GInstanceInitFunc of an object class
1404 * that has subclasses, make sure to pass the g_class parameter of the
1405 * #GInstanceInitFunc here.</note>
1407 * Returns: (transfer none) (nullable): the #GstPadTemplate with the
1408 * given name, or %NULL if none was found. No unreferencing is
1412 gst_element_class_get_pad_template (GstElementClass *
1413 element_class, const gchar * name)
1417 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1418 g_return_val_if_fail (name != NULL, NULL);
1420 padlist = element_class->padtemplates;
1423 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1425 if (strcmp (padtempl->name_template, name) == 0)
1428 padlist = g_list_next (padlist);
1434 static GstPadTemplate *
1435 gst_element_class_get_request_pad_template (GstElementClass *
1436 element_class, const gchar * name)
1438 GstPadTemplate *tmpl;
1440 tmpl = gst_element_class_get_pad_template (element_class, name);
1441 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1447 /* get a random pad on element of the given direction.
1448 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1451 gst_element_get_random_pad (GstElement * element,
1452 gboolean need_linked, GstPadDirection dir)
1454 GstPad *result = NULL;
1457 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1461 GST_OBJECT_LOCK (element);
1462 pads = element->srcpads;
1465 GST_OBJECT_LOCK (element);
1466 pads = element->sinkpads;
1469 goto wrong_direction;
1471 for (; pads; pads = g_list_next (pads)) {
1472 GstPad *pad = GST_PAD_CAST (pads->data);
1474 GST_OBJECT_LOCK (pad);
1475 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1476 GST_DEBUG_PAD_NAME (pad));
1478 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1479 /* if we require a linked pad, and it is not linked, continue the
1481 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1482 GST_DEBUG_PAD_NAME (pad));
1483 GST_OBJECT_UNLOCK (pad);
1486 /* found a pad, stop search */
1487 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1488 GST_DEBUG_PAD_NAME (pad));
1489 GST_OBJECT_UNLOCK (pad);
1495 gst_object_ref (result);
1497 GST_OBJECT_UNLOCK (element);
1501 /* ERROR handling */
1504 g_warning ("unknown pad direction %d", dir);
1510 gst_element_default_send_event (GstElement * element, GstEvent * event)
1512 gboolean result = FALSE;
1515 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1516 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK) :
1517 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC);
1520 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1521 "pushing %s event to random %s pad %s:%s",
1522 GST_EVENT_TYPE_NAME (event),
1523 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1524 GST_DEBUG_PAD_NAME (pad));
1526 result = gst_pad_send_event (pad, event);
1527 gst_object_unref (pad);
1529 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1530 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1531 gst_event_unref (event);
1537 * gst_element_send_event:
1538 * @element: a #GstElement to send the event to.
1539 * @event: (transfer full): the #GstEvent to send to the element.
1541 * Sends an event to an element. If the element doesn't implement an
1542 * event handler, the event will be pushed on a random linked sink pad for
1543 * downstream events or a random linked source pad for upstream events.
1545 * This function takes ownership of the provided event so you should
1546 * gst_event_ref() it if you want to reuse the event after this call.
1550 * Returns: %TRUE if the event was handled. Events that trigger a preroll (such
1551 * as flushing seeks and steps) will emit %GST_MESSAGE_ASYNC_DONE.
1554 gst_element_send_event (GstElement * element, GstEvent * event)
1556 GstElementClass *oclass;
1557 gboolean result = FALSE;
1559 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1560 g_return_val_if_fail (event != NULL, FALSE);
1562 oclass = GST_ELEMENT_GET_CLASS (element);
1564 GST_STATE_LOCK (element);
1565 if (oclass->send_event) {
1566 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1567 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1568 result = oclass->send_event (element, event);
1570 GST_STATE_UNLOCK (element);
1577 * @element: a #GstElement to send the event to.
1578 * @rate: The new playback rate
1579 * @format: The format of the seek values
1580 * @flags: The optional seek flags.
1581 * @start_type: The type and flags for the new start position
1582 * @start: The value of the new start position
1583 * @stop_type: The type and flags for the new stop position
1584 * @stop: The value of the new stop position
1586 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1587 * the parameters. The seek event is sent to the element using
1588 * gst_element_send_event().
1592 * Returns: %TRUE if the event was handled. Flushing seeks will trigger a
1593 * preroll, which will emit %GST_MESSAGE_ASYNC_DONE.
1596 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1597 GstSeekFlags flags, GstSeekType start_type, gint64 start,
1598 GstSeekType stop_type, gint64 stop)
1603 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1606 gst_event_new_seek (rate, format, flags, start_type, start, stop_type,
1608 result = gst_element_send_event (element, event);
1614 gst_element_default_query (GstElement * element, GstQuery * query)
1616 gboolean result = FALSE;
1619 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1621 result = gst_pad_query (pad, query);
1623 gst_object_unref (pad);
1625 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1627 GstPad *peer = gst_pad_get_peer (pad);
1630 result = gst_pad_query (peer, query);
1632 gst_object_unref (peer);
1634 gst_object_unref (pad);
1641 * gst_element_query:
1642 * @element: a #GstElement to perform the query on.
1643 * @query: (transfer none): the #GstQuery.
1645 * Performs a query on the given element.
1647 * For elements that don't implement a query handler, this function
1648 * forwards the query to a random srcpad or to the peer of a
1649 * random linked sinkpad of this element.
1651 * Please note that some queries might need a running pipeline to work.
1653 * Returns: %TRUE if the query could be performed.
1658 gst_element_query (GstElement * element, GstQuery * query)
1660 GstElementClass *klass;
1662 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1663 g_return_val_if_fail (query != NULL, FALSE);
1665 klass = GST_ELEMENT_GET_CLASS (element);
1667 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1668 GST_ELEMENT_NAME (element));
1669 return klass->query (element, query);
1676 gst_element_post_message_default (GstElement * element, GstMessage * message)
1679 gboolean result = FALSE;
1681 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1682 g_return_val_if_fail (message != NULL, FALSE);
1684 GST_OBJECT_LOCK (element);
1687 if (G_UNLIKELY (bus == NULL))
1690 gst_object_ref (bus);
1691 GST_OBJECT_UNLOCK (element);
1693 /* we release the element lock when posting the message so that any
1694 * (synchronous) message handlers can operate on the element */
1695 result = gst_bus_post (bus, message);
1696 gst_object_unref (bus);
1703 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1704 "not posting message %p: no bus", message);
1705 GST_OBJECT_UNLOCK (element);
1706 gst_message_unref (message);
1712 * gst_element_post_message:
1713 * @element: a #GstElement posting the message
1714 * @message: (transfer full): a #GstMessage to post
1716 * Post a message on the element's #GstBus. This function takes ownership of the
1717 * message; if you want to access the message after this call, you should add an
1718 * additional reference before calling.
1720 * Returns: %TRUE if the message was successfully posted. The function returns
1721 * %FALSE if the element did not have a bus.
1726 gst_element_post_message (GstElement * element, GstMessage * message)
1728 GstElementClass *klass;
1730 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1731 g_return_val_if_fail (message != NULL, FALSE);
1733 klass = GST_ELEMENT_GET_CLASS (element);
1734 if (klass->post_message)
1735 return klass->post_message (element, message);
1741 * _gst_element_error_printf:
1742 * @format: (allow-none): the printf-like format to use, or %NULL
1744 * This function is only used internally by the gst_element_error() macro.
1746 * Returns: (transfer full) (nullable): a newly allocated string, or
1747 * %NULL if the format was %NULL or ""
1752 _gst_element_error_printf (const gchar * format, ...)
1763 va_start (args, format);
1765 len = __gst_vasprintf (&buffer, format, args);
1776 * gst_element_message_full:
1777 * @element: a #GstElement to send message from
1778 * @type: the #GstMessageType
1779 * @domain: the GStreamer GError domain this message belongs to
1780 * @code: the GError code belonging to the domain
1781 * @text: (allow-none) (transfer full): an allocated text string to be used
1782 * as a replacement for the default message connected to code,
1784 * @debug: (allow-none) (transfer full): an allocated debug message to be
1785 * used as a replacement for the default debugging information,
1787 * @file: the source code file where the error was generated
1788 * @function: the source code function where the error was generated
1789 * @line: the source code line where the error was generated
1791 * Post an error, warning or info message on the bus from inside an element.
1793 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1794 * #GST_MESSAGE_INFO.
1798 void gst_element_message_full
1799 (GstElement * element, GstMessageType type,
1800 GQuark domain, gint code, gchar * text,
1801 gchar * debug, const gchar * file, const gchar * function, gint line)
1803 GError *gerror = NULL;
1807 gboolean has_debug = TRUE;
1808 GstMessage *message = NULL;
1811 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1812 g_return_if_fail (GST_IS_ELEMENT (element));
1813 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1814 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1816 /* check if we send the given text or the default error text */
1817 if ((text == NULL) || (text[0] == 0)) {
1818 /* text could have come from g_strdup_printf (""); */
1820 sent_text = gst_error_get_message (domain, code);
1824 /* construct a sent_debug with extra information from source */
1825 if ((debug == NULL) || (debug[0] == 0)) {
1826 /* debug could have come from g_strdup_printf (""); */
1830 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1832 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1833 file, line, function, name, debug);
1835 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1836 file, line, function, name);
1840 /* create gerror and post message */
1841 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1843 gerror = g_error_new_literal (domain, code, sent_text);
1846 case GST_MESSAGE_ERROR:
1848 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1850 case GST_MESSAGE_WARNING:
1851 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1854 case GST_MESSAGE_INFO:
1855 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1859 g_assert_not_reached ();
1862 gst_element_post_message (element, message);
1864 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1865 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1868 g_error_free (gerror);
1869 g_free (sent_debug);
1874 * gst_element_is_locked_state:
1875 * @element: a #GstElement.
1877 * Checks if the state of an element is locked.
1878 * If the state of an element is locked, state changes of the parent don't
1879 * affect the element.
1880 * This way you can leave currently unused elements inside bins. Just lock their
1881 * state before changing the state from #GST_STATE_NULL.
1885 * Returns: %TRUE, if the element's state is locked.
1888 gst_element_is_locked_state (GstElement * element)
1892 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1894 GST_OBJECT_LOCK (element);
1895 result = GST_ELEMENT_IS_LOCKED_STATE (element);
1896 GST_OBJECT_UNLOCK (element);
1902 * gst_element_set_locked_state:
1903 * @element: a #GstElement
1904 * @locked_state: %TRUE to lock the element's state
1906 * Locks the state of an element, so state changes of the parent don't affect
1907 * this element anymore.
1911 * Returns: %TRUE if the state was changed, %FALSE if bad parameters were given
1912 * or the elements state-locking needed no change.
1915 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1919 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1921 GST_OBJECT_LOCK (element);
1922 old = GST_ELEMENT_IS_LOCKED_STATE (element);
1924 if (G_UNLIKELY (old == locked_state))
1928 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1929 GST_ELEMENT_NAME (element));
1930 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1932 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1933 GST_ELEMENT_NAME (element));
1934 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1936 GST_OBJECT_UNLOCK (element);
1942 GST_CAT_DEBUG (GST_CAT_STATES,
1943 "elements %s was already in locked state %d",
1944 GST_ELEMENT_NAME (element), old);
1945 GST_OBJECT_UNLOCK (element);
1952 * gst_element_sync_state_with_parent:
1953 * @element: a #GstElement.
1955 * Tries to change the state of the element to the same as its parent.
1956 * If this function returns %FALSE, the state of element is undefined.
1958 * Returns: %TRUE, if the element's state could be synced to the parent's state.
1963 gst_element_sync_state_with_parent (GstElement * element)
1967 GstStateChangeReturn ret;
1969 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1971 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1972 GstState parent_current, parent_pending;
1974 GST_OBJECT_LOCK (parent);
1975 parent_current = GST_STATE (parent);
1976 parent_pending = GST_STATE_PENDING (parent);
1977 GST_OBJECT_UNLOCK (parent);
1979 /* set to pending if there is one, else we set it to the current state of
1981 if (parent_pending != GST_STATE_VOID_PENDING)
1982 target = parent_pending;
1984 target = parent_current;
1986 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1987 "syncing state (%s) to parent %s %s (%s, %s)",
1988 gst_element_state_get_name (GST_STATE (element)),
1989 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1990 gst_element_state_get_name (parent_current),
1991 gst_element_state_get_name (parent_pending));
1993 ret = gst_element_set_state (element, target);
1994 if (ret == GST_STATE_CHANGE_FAILURE)
1997 gst_object_unref (parent);
2001 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
2008 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2009 "syncing state failed (%s)",
2010 gst_element_state_change_return_get_name (ret));
2011 gst_object_unref (parent);
2017 static GstStateChangeReturn
2018 gst_element_get_state_func (GstElement * element,
2019 GstState * state, GstState * pending, GstClockTime timeout)
2021 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2022 GstState old_pending;
2024 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2025 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2027 GST_OBJECT_LOCK (element);
2028 ret = GST_STATE_RETURN (element);
2029 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2030 gst_element_state_change_return_get_name (ret));
2032 /* we got an error, report immediately */
2033 if (ret == GST_STATE_CHANGE_FAILURE)
2036 /* we got no_preroll, report immediately */
2037 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2040 /* no need to wait async if we are not async */
2041 if (ret != GST_STATE_CHANGE_ASYNC)
2044 old_pending = GST_STATE_PENDING (element);
2045 if (old_pending != GST_STATE_VOID_PENDING) {
2049 /* get cookie to detect state changes during waiting */
2050 cookie = element->state_cookie;
2052 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2053 "waiting for element to commit state");
2055 /* we have a pending state change, wait for it to complete */
2056 if (timeout != GST_CLOCK_TIME_NONE) {
2058 /* make timeout absolute */
2059 end_time = g_get_monotonic_time () + (timeout / 1000);
2060 signaled = GST_STATE_WAIT_UNTIL (element, end_time);
2062 GST_STATE_WAIT (element);
2067 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2068 /* timeout triggered */
2069 ret = GST_STATE_CHANGE_ASYNC;
2071 if (cookie != element->state_cookie)
2074 /* could be success or failure */
2075 if (old_pending == GST_STATE (element)) {
2076 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2077 ret = GST_STATE_CHANGE_SUCCESS;
2079 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2080 ret = GST_STATE_CHANGE_FAILURE;
2083 /* if nothing is pending anymore we can return SUCCESS */
2084 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2085 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2086 ret = GST_STATE_CHANGE_SUCCESS;
2092 *state = GST_STATE (element);
2094 *pending = GST_STATE_PENDING (element);
2096 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2097 "state current: %s, pending: %s, result: %s",
2098 gst_element_state_get_name (GST_STATE (element)),
2099 gst_element_state_get_name (GST_STATE_PENDING (element)),
2100 gst_element_state_change_return_get_name (ret));
2101 GST_OBJECT_UNLOCK (element);
2108 *state = GST_STATE_VOID_PENDING;
2110 *pending = GST_STATE_VOID_PENDING;
2112 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2114 GST_OBJECT_UNLOCK (element);
2116 return GST_STATE_CHANGE_FAILURE;
2121 * gst_element_get_state:
2122 * @element: a #GstElement to get the state of.
2123 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2125 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2126 * state. Can be %NULL.
2127 * @timeout: a #GstClockTime to specify the timeout for an async
2128 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2130 * Gets the state of the element.
2132 * For elements that performed an ASYNC state change, as reported by
2133 * gst_element_set_state(), this function will block up to the
2134 * specified timeout value for the state change to complete.
2135 * If the element completes the state change or goes into
2136 * an error, this function returns immediately with a return value of
2137 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2139 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2140 * returns the current and pending state immediately.
2142 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2143 * successfully changed its state but is not able to provide data yet.
2144 * This mostly happens for live sources that only produce data in
2145 * %GST_STATE_PLAYING. While the state change return is equivalent to
2146 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2147 * some sink elements might not be able to complete their state change because
2148 * an element is not producing data to complete the preroll. When setting the
2149 * element to playing, the preroll will complete and playback will start.
2151 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2152 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2153 * element is still performing a state change or
2154 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2158 GstStateChangeReturn
2159 gst_element_get_state (GstElement * element,
2160 GstState * state, GstState * pending, GstClockTime timeout)
2162 GstElementClass *oclass;
2163 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2165 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2167 oclass = GST_ELEMENT_GET_CLASS (element);
2169 if (oclass->get_state)
2170 result = (oclass->get_state) (element, state, pending, timeout);
2176 * gst_element_abort_state:
2177 * @element: a #GstElement to abort the state of.
2179 * Abort the state change of the element. This function is used
2180 * by elements that do asynchronous state changes and find out
2181 * something is wrong.
2183 * This function should be called with the STATE_LOCK held.
2188 gst_element_abort_state (GstElement * element)
2192 #ifndef GST_DISABLE_GST_DEBUG
2196 g_return_if_fail (GST_IS_ELEMENT (element));
2198 GST_OBJECT_LOCK (element);
2199 pending = GST_STATE_PENDING (element);
2201 if (pending == GST_STATE_VOID_PENDING ||
2202 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2203 goto nothing_aborted;
2205 #ifndef GST_DISABLE_GST_DEBUG
2206 old_state = GST_STATE (element);
2208 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2209 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2210 gst_element_state_get_name (pending));
2214 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2216 GST_STATE_BROADCAST (element);
2217 GST_OBJECT_UNLOCK (element);
2223 GST_OBJECT_UNLOCK (element);
2228 /* Not static because GstBin has manual state handling too */
2230 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2231 GstState newstate, GstState pending)
2233 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2234 GstMessage *message;
2236 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2237 "notifying about state-changed %s to %s (%s pending)",
2238 gst_element_state_get_name (oldstate),
2239 gst_element_state_get_name (newstate),
2240 gst_element_state_get_name (pending));
2242 if (klass->state_changed)
2243 klass->state_changed (element, oldstate, newstate, pending);
2245 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2246 oldstate, newstate, pending);
2247 gst_element_post_message (element, message);
2251 * gst_element_continue_state:
2252 * @element: a #GstElement to continue the state change of.
2253 * @ret: The previous state return value
2255 * Commit the state change of the element and proceed to the next
2256 * pending state if any. This function is used
2257 * by elements that do asynchronous state changes.
2258 * The core will normally call this method automatically when an
2259 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2261 * If after calling this method the element still has not reached
2262 * the pending state, the next state change is performed.
2264 * This method is used internally and should normally not be called by plugins
2267 * Returns: The result of the commit state change.
2271 GstStateChangeReturn
2272 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2274 GstStateChangeReturn old_ret;
2275 GstState old_state, old_next;
2276 GstState current, next, pending;
2277 GstStateChange transition;
2279 GST_OBJECT_LOCK (element);
2280 old_ret = GST_STATE_RETURN (element);
2281 GST_STATE_RETURN (element) = ret;
2282 pending = GST_STATE_PENDING (element);
2284 /* check if there is something to commit */
2285 if (pending == GST_STATE_VOID_PENDING)
2286 goto nothing_pending;
2288 old_state = GST_STATE (element);
2289 /* this is the state we should go to next */
2290 old_next = GST_STATE_NEXT (element);
2291 /* update current state */
2292 current = GST_STATE (element) = old_next;
2294 /* see if we reached the final state */
2295 if (pending == current)
2298 next = GST_STATE_GET_NEXT (current, pending);
2299 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2301 GST_STATE_NEXT (element) = next;
2303 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2304 GST_OBJECT_UNLOCK (element);
2306 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2307 "committing state from %s to %s, pending %s, next %s",
2308 gst_element_state_get_name (old_state),
2309 gst_element_state_get_name (old_next),
2310 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2312 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2314 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2315 "continue state change %s to %s, final %s",
2316 gst_element_state_get_name (current),
2317 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2319 ret = gst_element_change_state (element, transition);
2325 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2326 GST_OBJECT_UNLOCK (element);
2331 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2332 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2334 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2335 "completed state change to %s", gst_element_state_get_name (pending));
2336 GST_OBJECT_UNLOCK (element);
2338 /* don't post silly messages with the same state. This can happen
2339 * when an element state is changed to what it already was. For bins
2340 * this can be the result of a lost state, which we check with the
2341 * previous return value.
2342 * We do signal the cond though as a _get_state() might be blocking
2344 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2345 _priv_gst_element_state_changed (element, old_state, old_next,
2346 GST_STATE_VOID_PENDING);
2348 GST_STATE_BROADCAST (element);
2355 * gst_element_lost_state:
2356 * @element: a #GstElement the state is lost of
2358 * Brings the element to the lost state. The current state of the
2359 * element is copied to the pending state so that any call to
2360 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2362 * An ASYNC_START message is posted. If the element was PLAYING, it will
2363 * go to PAUSED. The element will be restored to its PLAYING state by
2364 * the parent pipeline when it prerolls again.
2366 * This is mostly used for elements that lost their preroll buffer
2367 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2368 * they will go to their pending state again when a new preroll buffer is
2369 * queued. This function can only be called when the element is currently
2370 * not in error or an async state change.
2372 * This function is used internally and should normally not be called from
2373 * plugins or applications.
2376 gst_element_lost_state (GstElement * element)
2378 GstState old_state, new_state;
2379 GstMessage *message;
2381 g_return_if_fail (GST_IS_ELEMENT (element));
2383 GST_OBJECT_LOCK (element);
2384 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2387 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2388 goto only_async_start;
2390 old_state = GST_STATE (element);
2392 /* when we were PLAYING, the new state is PAUSED. We will also not
2393 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2394 * when we preroll. */
2395 if (old_state > GST_STATE_PAUSED)
2396 new_state = GST_STATE_PAUSED;
2398 new_state = old_state;
2400 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2401 "lost state of %s to %s", gst_element_state_get_name (old_state),
2402 gst_element_state_get_name (new_state));
2404 GST_STATE (element) = new_state;
2405 GST_STATE_NEXT (element) = new_state;
2406 GST_STATE_PENDING (element) = new_state;
2407 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2408 GST_OBJECT_UNLOCK (element);
2410 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2412 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2413 gst_element_post_message (element, message);
2419 GST_OBJECT_UNLOCK (element);
2424 GST_OBJECT_UNLOCK (element);
2426 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2427 gst_element_post_message (element, message);
2433 * gst_element_set_state:
2434 * @element: a #GstElement to change state of.
2435 * @state: the element's new #GstState.
2437 * Sets the state of the element. This function will try to set the
2438 * requested state by going through all the intermediary states and calling
2439 * the class's state change function for each.
2441 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2442 * element will perform the remainder of the state change asynchronously in
2444 * An application can use gst_element_get_state() to wait for the completion
2445 * of the state change or it can wait for a %GST_MESSAGE_ASYNC_DONE or
2446 * %GST_MESSAGE_STATE_CHANGED on the bus.
2448 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2449 * #GST_STATE_CHANGE_ASYNC.
2451 * Returns: Result of the state change using #GstStateChangeReturn.
2455 GstStateChangeReturn
2456 gst_element_set_state (GstElement * element, GstState state)
2458 GstElementClass *oclass;
2459 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2461 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2463 oclass = GST_ELEMENT_GET_CLASS (element);
2465 if (oclass->set_state)
2466 result = (oclass->set_state) (element, state);
2472 * default set state function, calculates the next state based
2473 * on current state and calls the change_state function
2475 static GstStateChangeReturn
2476 gst_element_set_state_func (GstElement * element, GstState state)
2478 GstState current, next, old_pending;
2479 GstStateChangeReturn ret;
2480 GstStateChange transition;
2481 GstStateChangeReturn old_ret;
2483 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2485 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2486 gst_element_state_get_name (state));
2488 /* state lock is taken to protect the set_state() and get_state()
2489 * procedures, it does not lock any variables. */
2490 GST_STATE_LOCK (element);
2492 /* now calculate how to get to the new state */
2493 GST_OBJECT_LOCK (element);
2494 old_ret = GST_STATE_RETURN (element);
2495 /* previous state change returned an error, remove all pending
2496 * and next states */
2497 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2498 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2499 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2500 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2503 current = GST_STATE (element);
2504 next = GST_STATE_NEXT (element);
2505 old_pending = GST_STATE_PENDING (element);
2507 /* this is the (new) state we should go to. TARGET is the last state we set on
2509 if (state != GST_STATE_TARGET (element)) {
2510 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2511 "setting target state to %s", gst_element_state_get_name (state));
2512 GST_STATE_TARGET (element) = state;
2513 /* increment state cookie so that we can track each state change. We only do
2514 * this if this is actually a new state change. */
2515 element->state_cookie++;
2517 GST_STATE_PENDING (element) = state;
2519 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2520 "current %s, old_pending %s, next %s, old return %s",
2521 gst_element_state_get_name (current),
2522 gst_element_state_get_name (old_pending),
2523 gst_element_state_get_name (next),
2524 gst_element_state_change_return_get_name (old_ret));
2526 /* if the element was busy doing a state change, we just update the
2527 * target state, it'll get to it async then. */
2528 if (old_pending != GST_STATE_VOID_PENDING) {
2529 /* upwards state change will happen ASYNC */
2530 if (old_pending <= state)
2532 /* element is going to this state already */
2533 else if (next == state)
2535 /* element was performing an ASYNC upward state change and
2536 * we request to go downward again. Start from the next pending
2538 else if (next > state
2539 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2543 next = GST_STATE_GET_NEXT (current, state);
2544 /* now we store the next state */
2545 GST_STATE_NEXT (element) = next;
2546 /* mark busy, we need to check that there is actually a state change
2547 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2548 * the default element change_state function has no way to know what the
2549 * old value was... could consider this a FIXME...*/
2550 if (current != next)
2551 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2553 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2555 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2556 "%s: setting state from %s to %s",
2557 (next != state ? "intermediate" : "final"),
2558 gst_element_state_get_name (current), gst_element_state_get_name (next));
2560 /* now signal any waiters, they will error since the cookie was incremented */
2561 GST_STATE_BROADCAST (element);
2563 GST_OBJECT_UNLOCK (element);
2565 ret = gst_element_change_state (element, transition);
2567 GST_STATE_UNLOCK (element);
2569 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2570 gst_element_state_change_return_get_name (ret));
2576 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2577 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2578 "element was busy with async state change");
2579 GST_OBJECT_UNLOCK (element);
2581 GST_STATE_UNLOCK (element);
2583 return GST_STATE_CHANGE_ASYNC;
2588 * gst_element_change_state:
2589 * @element: a #GstElement
2590 * @transition: the requested transition
2592 * Perform @transition on @element.
2594 * This function must be called with STATE_LOCK held and is mainly used
2597 * Returns: the #GstStateChangeReturn of the state transition.
2599 GstStateChangeReturn
2600 gst_element_change_state (GstElement * element, GstStateChange transition)
2602 GstElementClass *oclass;
2603 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2605 oclass = GST_ELEMENT_GET_CLASS (element);
2607 /* call the state change function so it can set the state */
2608 if (oclass->change_state)
2609 ret = (oclass->change_state) (element, transition);
2611 ret = GST_STATE_CHANGE_FAILURE;
2614 case GST_STATE_CHANGE_FAILURE:
2615 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2616 "have FAILURE change_state return");
2617 /* state change failure */
2618 gst_element_abort_state (element);
2620 case GST_STATE_CHANGE_ASYNC:
2624 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2625 "element will change state ASYNC");
2627 target = GST_STATE_TARGET (element);
2629 if (target > GST_STATE_READY)
2632 /* else we just continue the state change downwards */
2633 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2634 "forcing commit state %s <= %s",
2635 gst_element_state_get_name (target),
2636 gst_element_state_get_name (GST_STATE_READY));
2638 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2641 case GST_STATE_CHANGE_SUCCESS:
2642 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2643 "element changed state SUCCESS");
2644 /* we can commit the state now which will proceeed to
2646 ret = gst_element_continue_state (element, ret);
2648 case GST_STATE_CHANGE_NO_PREROLL:
2649 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2650 "element changed state NO_PREROLL");
2651 /* we can commit the state now which will proceeed to
2653 ret = gst_element_continue_state (element, ret);
2656 goto invalid_return;
2659 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2664 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2672 GST_OBJECT_LOCK (element);
2673 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2674 g_critical ("%s: unknown return value %d from a state change function",
2675 GST_ELEMENT_NAME (element), ret);
2677 /* we are in error now */
2678 ret = GST_STATE_CHANGE_FAILURE;
2679 GST_STATE_RETURN (element) = ret;
2680 GST_OBJECT_UNLOCK (element);
2686 /* gst_iterator_fold functions for pads_activate
2687 * Stop the iterator if activating one pad failed, but only if that pad
2688 * has not been removed from the element. */
2690 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2692 GstPad *pad = g_value_get_object (vpad);
2693 gboolean cont = TRUE;
2695 if (!gst_pad_set_active (pad, *active)) {
2696 if (GST_PAD_PARENT (pad) != NULL) {
2698 g_value_set_boolean (ret, FALSE);
2705 /* returns false on error or early cutout of the fold, true if all
2706 * pads in @iter were (de)activated successfully. */
2708 iterator_activate_fold_with_resync (GstIterator * iter,
2709 GstIteratorFoldFunction func, gpointer user_data)
2711 GstIteratorResult ires;
2714 /* no need to unset this later, it's just a boolean */
2715 g_value_init (&ret, G_TYPE_BOOLEAN);
2716 g_value_set_boolean (&ret, TRUE);
2719 ires = gst_iterator_fold (iter, func, &ret, user_data);
2721 case GST_ITERATOR_RESYNC:
2722 /* need to reset the result again */
2723 g_value_set_boolean (&ret, TRUE);
2724 gst_iterator_resync (iter);
2726 case GST_ITERATOR_DONE:
2727 /* all pads iterated, return collected value */
2730 /* iterator returned _ERROR or premature end with _OK,
2731 * mark an error and exit */
2732 g_value_set_boolean (&ret, FALSE);
2737 /* return collected value */
2738 return g_value_get_boolean (&ret);
2741 /* is called with STATE_LOCK
2743 * Pads are activated from source pads to sinkpads.
2746 gst_element_pads_activate (GstElement * element, gboolean active)
2751 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2752 "%s pads", active ? "activate" : "deactivate");
2754 iter = gst_element_iterate_src_pads (element);
2756 iterator_activate_fold_with_resync (iter,
2757 (GstIteratorFoldFunction) activate_pads, &active);
2758 gst_iterator_free (iter);
2759 if (G_UNLIKELY (!res))
2762 iter = gst_element_iterate_sink_pads (element);
2764 iterator_activate_fold_with_resync (iter,
2765 (GstIteratorFoldFunction) activate_pads, &active);
2766 gst_iterator_free (iter);
2767 if (G_UNLIKELY (!res))
2770 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2771 "pad %sactivation successful", active ? "" : "de");
2778 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2779 "pad %sactivation failed", active ? "" : "de");
2784 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2785 "sink pads_activate failed");
2790 /* is called with STATE_LOCK */
2791 static GstStateChangeReturn
2792 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2794 GstState state, next;
2795 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2797 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2799 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2800 next = GST_STATE_TRANSITION_NEXT (transition);
2802 /* if the element already is in the given state, we just return success */
2803 if (next == GST_STATE_VOID_PENDING || state == next)
2806 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2807 "default handler tries setting state from %s to %s (%04x)",
2808 gst_element_state_get_name (state),
2809 gst_element_state_get_name (next), transition);
2811 switch (transition) {
2812 case GST_STATE_CHANGE_NULL_TO_READY:
2814 case GST_STATE_CHANGE_READY_TO_PAUSED:
2815 if (!gst_element_pads_activate (element, TRUE)) {
2816 result = GST_STATE_CHANGE_FAILURE;
2819 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2821 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2823 case GST_STATE_CHANGE_PAUSED_TO_READY:
2824 case GST_STATE_CHANGE_READY_TO_NULL:
2825 /* deactivate pads in both cases, since they are activated on
2826 ready->paused but the element might not have made it to paused */
2827 if (!gst_element_pads_activate (element, FALSE)) {
2828 result = GST_STATE_CHANGE_FAILURE;
2832 /* this will catch real but unhandled state changes;
2833 * can only be caused by:
2834 * - a new state was added
2835 * - somehow the element was asked to jump across an intermediate state
2837 g_warning ("Unhandled state change from %s to %s",
2838 gst_element_state_get_name (state),
2839 gst_element_state_get_name (next));
2846 GST_OBJECT_LOCK (element);
2847 result = GST_STATE_RETURN (element);
2848 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2849 "element is already in the %s state",
2850 gst_element_state_get_name (state));
2851 GST_OBJECT_UNLOCK (element);
2858 * gst_element_get_factory:
2859 * @element: a #GstElement to request the element factory of.
2861 * Retrieves the factory that was used to create this element.
2863 * Returns: (transfer none): the #GstElementFactory used for creating this
2864 * element. no refcounting is needed.
2867 gst_element_get_factory (GstElement * element)
2869 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2871 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2875 gst_element_dispose (GObject * object)
2877 GstElement *element = GST_ELEMENT_CAST (object);
2880 GstElementClass *oclass;
2883 oclass = GST_ELEMENT_GET_CLASS (element);
2885 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2887 if (GST_STATE (element) != GST_STATE_NULL)
2890 /* start by releasing all request pads, this might also remove some dynamic
2892 walk = element->pads;
2894 GstPad *pad = GST_PAD_CAST (walk->data);
2898 if (oclass->release_pad && GST_PAD_PAD_TEMPLATE (pad) &&
2899 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
2900 == GST_PAD_REQUEST) {
2901 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2902 "removing request pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2903 oclass->release_pad (element, pad);
2905 /* in case the release_pad function removed the next pad too */
2906 if (walk && g_list_position (element->pads, walk) == -1)
2907 walk = element->pads;
2910 /* remove the remaining pads */
2911 while (element->pads) {
2912 GstPad *pad = GST_PAD_CAST (element->pads->data);
2913 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2914 "removing pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2915 if (!gst_element_remove_pad (element, pad)) {
2916 /* only happens when someone unparented our pad.. */
2917 g_critical ("failed to remove pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2922 GST_OBJECT_LOCK (element);
2923 clock_p = &element->clock;
2924 bus_p = &element->bus;
2925 gst_object_replace ((GstObject **) clock_p, NULL);
2926 gst_object_replace ((GstObject **) bus_p, NULL);
2927 GST_OBJECT_UNLOCK (element);
2929 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2931 G_OBJECT_CLASS (parent_class)->dispose (object);
2940 is_locked = GST_ELEMENT_IS_LOCKED_STATE (element);
2942 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2944 "You need to explicitly set elements to the NULL state before\n"
2945 "dropping the final reference, to allow them to clean up.\n"
2946 "This problem may also be caused by a refcounting bug in the\n"
2947 "application or some element.\n",
2948 GST_OBJECT_NAME (element),
2949 gst_element_state_get_name (GST_STATE (element)),
2950 is_locked ? " (locked)" : "");
2956 gst_element_finalize (GObject * object)
2958 GstElement *element = GST_ELEMENT_CAST (object);
2960 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2962 g_cond_clear (&element->state_cond);
2963 g_rec_mutex_clear (&element->state_lock);
2965 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2967 G_OBJECT_CLASS (parent_class)->finalize (object);
2971 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2975 g_return_if_fail (GST_IS_ELEMENT (element));
2977 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2979 GST_OBJECT_LOCK (element);
2980 bus_p = &GST_ELEMENT_BUS (element);
2981 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
2982 GST_OBJECT_UNLOCK (element);
2986 * gst_element_set_bus:
2987 * @element: a #GstElement to set the bus of.
2988 * @bus: (transfer none): the #GstBus to set.
2990 * Sets the bus of the element. Increases the refcount on the bus.
2991 * For internal use only, unless you're testing elements.
2996 gst_element_set_bus (GstElement * element, GstBus * bus)
2998 GstElementClass *oclass;
3000 g_return_if_fail (GST_IS_ELEMENT (element));
3002 oclass = GST_ELEMENT_GET_CLASS (element);
3004 if (oclass->set_bus)
3005 oclass->set_bus (element, bus);
3009 * gst_element_get_bus:
3010 * @element: a #GstElement to get the bus of.
3012 * Returns the bus of the element. Note that only a #GstPipeline will provide a
3013 * bus for the application.
3015 * Returns: (transfer full): the element's #GstBus. unref after usage.
3020 gst_element_get_bus (GstElement * element)
3022 GstBus *result = NULL;
3024 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3026 GST_OBJECT_LOCK (element);
3027 if ((result = GST_ELEMENT_BUS (element)))
3028 gst_object_ref (result);
3029 GST_OBJECT_UNLOCK (element);
3031 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,
3038 * gst_element_set_context:
3039 * @element: a #GstElement to set the context of.
3040 * @context: (transfer none): the #GstContext to set.
3042 * Sets the context of the element. Increases the refcount of the context.
3047 gst_element_set_context (GstElement * element, GstContext * context)
3049 GstElementClass *oclass;
3051 g_return_if_fail (GST_IS_ELEMENT (element));
3053 oclass = GST_ELEMENT_GET_CLASS (element);
3055 GST_CAT_DEBUG_OBJECT (GST_CAT_CONTEXT, element,
3056 "set context %p %" GST_PTR_FORMAT, context,
3057 gst_context_get_structure (context));
3059 if (oclass->set_context)
3060 oclass->set_context (element, context);