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);
642 /* locking pad to look at the name */
643 GST_OBJECT_LOCK (pad);
644 pad_name = g_strdup (GST_PAD_NAME (pad));
645 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
646 GST_STR_NULL (pad_name));
647 flushing = GST_PAD_IS_FLUSHING (pad);
648 GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_NEED_PARENT);
649 GST_OBJECT_UNLOCK (pad);
651 /* then check to see if there's already a pad by that name here */
652 GST_OBJECT_LOCK (element);
653 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
656 /* try to set the pad's parent */
657 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
658 GST_OBJECT_CAST (element))))
661 /* check for flushing pads */
662 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
663 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
664 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
665 "use gst_pad_set_active(pad,TRUE) before adding it.",
666 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
668 GST_OBJECT_LOCK (pad);
669 GST_PAD_UNSET_FLUSHING (pad);
670 GST_OBJECT_UNLOCK (pad);
675 /* add it to the list */
676 switch (gst_pad_get_direction (pad)) {
678 element->srcpads = g_list_append (element->srcpads, pad);
679 element->numsrcpads++;
682 element->sinkpads = g_list_append (element->sinkpads, pad);
683 element->numsinkpads++;
688 element->pads = g_list_append (element->pads, pad);
690 element->pads_cookie++;
691 GST_OBJECT_UNLOCK (element);
693 /* emit the PAD_ADDED signal */
694 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
701 g_critical ("Padname %s is not unique in element %s, not adding",
702 pad_name, GST_ELEMENT_NAME (element));
703 GST_OBJECT_UNLOCK (element);
710 ("Pad %s already has parent when trying to add to element %s",
711 pad_name, GST_ELEMENT_NAME (element));
712 GST_OBJECT_UNLOCK (element);
718 GST_OBJECT_LOCK (pad);
720 ("Trying to add pad %s to element %s, but it has no direction",
721 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
722 GST_OBJECT_UNLOCK (pad);
723 GST_OBJECT_UNLOCK (element);
729 * gst_element_remove_pad:
730 * @element: a #GstElement to remove pad from.
731 * @pad: (transfer full): the #GstPad to remove from the element.
733 * Removes @pad from @element. @pad will be destroyed if it has not been
734 * referenced elsewhere using gst_object_unparent().
736 * This function is used by plugin developers and should not be used
737 * by applications. Pads that were dynamically requested from elements
738 * with gst_element_request_pad() should be released with the
739 * gst_element_release_request_pad() function instead.
741 * Pads are not automatically deactivated so elements should perform the needed
742 * steps to deactivate the pad in case this pad is removed in the PAUSED or
743 * PLAYING state. See gst_pad_set_active() for more information about
746 * The pad and the element should be unlocked when calling this function.
748 * This function will emit the #GstElement::pad-removed signal on the element.
750 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
751 * pad does not belong to the provided element.
756 gst_element_remove_pad (GstElement * element, GstPad * pad)
760 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
761 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
763 /* locking pad to look at the name and parent */
764 GST_OBJECT_LOCK (pad);
765 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
766 GST_STR_NULL (GST_PAD_NAME (pad)));
768 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
770 GST_OBJECT_UNLOCK (pad);
773 if ((peer = gst_pad_get_peer (pad))) {
774 /* window for MT unsafeness, someone else could unlink here
775 * and then we call unlink with wrong pads. The unlink
776 * function would catch this and safely return failed. */
777 if (GST_PAD_IS_SRC (pad))
778 gst_pad_unlink (pad, peer);
780 gst_pad_unlink (peer, pad);
782 gst_object_unref (peer);
785 GST_OBJECT_LOCK (element);
786 /* remove it from the list */
787 switch (gst_pad_get_direction (pad)) {
789 element->srcpads = g_list_remove (element->srcpads, pad);
790 element->numsrcpads--;
793 element->sinkpads = g_list_remove (element->sinkpads, pad);
794 element->numsinkpads--;
797 g_critical ("Removing pad without direction???");
800 element->pads = g_list_remove (element->pads, pad);
802 element->pads_cookie++;
803 GST_OBJECT_UNLOCK (element);
805 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
806 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
808 gst_object_unparent (GST_OBJECT_CAST (pad));
815 /* locking order is element > pad */
816 GST_OBJECT_UNLOCK (pad);
818 GST_OBJECT_LOCK (element);
819 GST_OBJECT_LOCK (pad);
820 g_critical ("Padname %s:%s does not belong to element %s when removing",
821 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
822 GST_OBJECT_UNLOCK (pad);
823 GST_OBJECT_UNLOCK (element);
829 * gst_element_no_more_pads:
830 * @element: a #GstElement
832 * Use this function to signal that the element does not expect any more pads
833 * to show up in the current pipeline. This function should be called whenever
834 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
835 * pad templates use this in combination with autopluggers to figure out that
836 * the element is done initializing its pads.
838 * This function emits the #GstElement::no-more-pads signal.
843 gst_element_no_more_pads (GstElement * element)
845 g_return_if_fail (GST_IS_ELEMENT (element));
847 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
851 pad_compare_name (GstPad * pad1, const gchar * name)
855 GST_OBJECT_LOCK (pad1);
856 result = strcmp (GST_PAD_NAME (pad1), name);
857 GST_OBJECT_UNLOCK (pad1);
863 * gst_element_get_static_pad:
864 * @element: a #GstElement to find a static pad of.
865 * @name: the name of the static #GstPad to retrieve.
867 * Retrieves a pad from @element by name. This version only retrieves
868 * already-existing (i.e. 'static') pads.
870 * Returns: (transfer full) (nullable): the requested #GstPad if
871 * found, otherwise %NULL. unref after usage.
876 gst_element_get_static_pad (GstElement * element, const gchar * name)
879 GstPad *result = NULL;
881 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
882 g_return_val_if_fail (name != NULL, NULL);
884 GST_OBJECT_LOCK (element);
886 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
888 result = GST_PAD_CAST (find->data);
889 gst_object_ref (result);
892 if (result == NULL) {
893 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
894 name, GST_ELEMENT_NAME (element));
896 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
897 GST_ELEMENT_NAME (element), name);
899 GST_OBJECT_UNLOCK (element);
905 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
906 const gchar * name, const GstCaps * caps)
908 GstPad *newpad = NULL;
909 GstElementClass *oclass;
911 oclass = GST_ELEMENT_GET_CLASS (element);
913 #ifndef G_DISABLE_CHECKS
914 /* Some sanity checking here */
918 /* Is this the template name? */
919 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
920 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
922 const gchar *str, *data;
925 /* Otherwise check if it's a valid name for the name template */
926 str = strchr (templ->name_template, '%');
927 g_return_val_if_fail (str != NULL, NULL);
928 g_return_val_if_fail (strncmp (templ->name_template, name,
929 str - templ->name_template) == 0, NULL);
930 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
932 data = name + (str - templ->name_template);
934 /* Can either be %s or %d or %u, do sanity checking for %d */
935 if (*(str + 1) == 'd') {
939 tmp = g_ascii_strtoll (data, &endptr, 10);
940 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
941 && *endptr == '\0', NULL);
942 } else if (*(str + 1) == 'u') {
946 tmp = g_ascii_strtoull (data, &endptr, 10);
947 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
951 pad = gst_element_get_static_pad (element, name);
953 gst_object_unref (pad);
954 /* FIXME 2.0: Change this to g_return_val_if_fail() */
955 g_critical ("Element %s already has a pad named %s, the behaviour of "
956 " gst_element_get_request_pad() for existing pads is undefined!",
957 GST_ELEMENT_NAME (element), name);
962 if (oclass->request_new_pad)
963 newpad = (oclass->request_new_pad) (element, templ, name, caps);
966 gst_object_ref (newpad);
972 * gst_element_get_request_pad:
973 * @element: a #GstElement to find a request pad of.
974 * @name: the name of the request #GstPad to retrieve.
976 * Retrieves a pad from the element by name (e.g. "src_\%d"). This version only
977 * retrieves request pads. The pad should be released with
978 * gst_element_release_request_pad().
980 * This method is slower than manually getting the pad template and calling
981 * gst_element_request_pad() if the pads should have a specific name (e.g.
982 * @name is "src_1" instead of "src_\%u").
984 * Returns: (transfer full) (nullable): requested #GstPad if found,
985 * otherwise %NULL. Release after usage.
988 gst_element_get_request_pad (GstElement * element, const gchar * name)
990 GstPadTemplate *templ = NULL;
992 const gchar *req_name = NULL;
993 gboolean templ_found = FALSE;
996 gchar *str, *endptr = NULL;
997 GstElementClass *class;
999 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1000 g_return_val_if_fail (name != NULL, NULL);
1002 class = GST_ELEMENT_GET_CLASS (element);
1004 /* if the name contains a %, we assume it's the complete template name. Get
1005 * the template and try to get a pad */
1006 if (strstr (name, "%")) {
1007 templ = gst_element_class_get_request_pad_template (class, name);
1012 /* there is no % in the name, try to find a matching template */
1013 list = class->padtemplates;
1014 while (!templ_found && list) {
1015 templ = (GstPadTemplate *) list->data;
1016 if (templ->presence == GST_PAD_REQUEST) {
1017 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1018 templ->name_template);
1019 /* see if we find an exact match */
1020 if (strcmp (name, templ->name_template) == 0) {
1025 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1026 and %d and %u, occurring at the end of the name_template, are the only
1028 else if ((str = strchr (templ->name_template, '%'))
1029 && strncmp (templ->name_template, name,
1030 str - templ->name_template) == 0
1031 && strlen (name) > str - templ->name_template) {
1032 data = name + (str - templ->name_template);
1033 if (*(str + 1) == 'd') {
1037 tmp = strtol (data, &endptr, 10);
1038 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1044 } else if (*(str + 1) == 'u') {
1048 tmp = strtoul (data, &endptr, 10);
1049 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1069 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1075 * gst_element_request_pad: (virtual request_new_pad)
1076 * @element: a #GstElement to find a request pad of.
1077 * @templ: a #GstPadTemplate of which we want a pad of.
1078 * @name: (transfer none) (allow-none): the name of the request #GstPad
1079 * to retrieve. Can be %NULL.
1080 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1081 * request. Can be %NULL.
1083 * Retrieves a request pad from the element according to the provided template.
1084 * Pad templates can be looked up using
1085 * gst_element_factory_get_static_pad_templates().
1087 * The pad should be released with gst_element_release_request_pad().
1089 * Returns: (transfer full) (nullable): requested #GstPad if found,
1090 * otherwise %NULL. Release after usage.
1093 gst_element_request_pad (GstElement * element,
1094 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1096 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1097 g_return_val_if_fail (templ != NULL, NULL);
1098 g_return_val_if_fail (templ->presence == GST_PAD_REQUEST, NULL);
1100 return _gst_element_request_pad (element, templ, name, caps);
1103 static GstIterator *
1104 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1106 GstIterator *result;
1108 GST_OBJECT_LOCK (element);
1109 result = gst_iterator_new_list (GST_TYPE_PAD,
1110 GST_OBJECT_GET_LOCK (element),
1111 &element->pads_cookie, padlist, (GObject *) element, NULL);
1112 GST_OBJECT_UNLOCK (element);
1118 * gst_element_iterate_pads:
1119 * @element: a #GstElement to iterate pads of.
1121 * Retrieves an iterator of @element's pads. The iterator should
1122 * be freed after usage. Also more specialized iterators exists such as
1123 * gst_element_iterate_src_pads() or gst_element_iterate_sink_pads().
1125 * The order of pads returned by the iterator will be the order in which
1126 * the pads were added to the element.
1128 * Returns: (transfer full): the #GstIterator of #GstPad.
1133 gst_element_iterate_pads (GstElement * element)
1135 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1137 return gst_element_iterate_pad_list (element, &element->pads);
1141 * gst_element_iterate_src_pads:
1142 * @element: a #GstElement.
1144 * Retrieves an iterator of @element's source pads.
1146 * The order of pads returned by the iterator will be the order in which
1147 * the pads were added to the element.
1149 * Returns: (transfer full): the #GstIterator of #GstPad.
1154 gst_element_iterate_src_pads (GstElement * element)
1156 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1158 return gst_element_iterate_pad_list (element, &element->srcpads);
1162 * gst_element_iterate_sink_pads:
1163 * @element: a #GstElement.
1165 * Retrieves an iterator of @element's sink pads.
1167 * The order of pads returned by the iterator will be the order in which
1168 * the pads were added to the element.
1170 * Returns: (transfer full): the #GstIterator of #GstPad.
1175 gst_element_iterate_sink_pads (GstElement * element)
1177 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1179 return gst_element_iterate_pad_list (element, &element->sinkpads);
1183 * gst_element_class_add_pad_template:
1184 * @klass: the #GstElementClass to add the pad template to.
1185 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1187 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1188 * functions of classes. If a pad template with the same name as an already
1189 * existing one is added the old one is replaced by the new one.
1193 gst_element_class_add_pad_template (GstElementClass * klass,
1194 GstPadTemplate * templ)
1196 GList *template_list = klass->padtemplates;
1198 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1199 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1201 /* If we already have a pad template with the same name replace the
1203 while (template_list) {
1204 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1206 /* Found pad with the same name, replace and return */
1207 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1208 gst_object_unref (padtempl);
1209 template_list->data = templ;
1212 template_list = g_list_next (template_list);
1215 /* Take ownership of the floating ref */
1216 gst_object_ref_sink (templ);
1218 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1219 klass->numpadtemplates++;
1223 * gst_element_class_add_metadata:
1224 * @klass: class to set metadata for
1225 * @key: the key to set
1226 * @value: the value to set
1228 * Set @key with @value as metadata in @klass.
1231 gst_element_class_add_metadata (GstElementClass * klass,
1232 const gchar * key, const gchar * value)
1234 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1235 g_return_if_fail (key != NULL);
1236 g_return_if_fail (value != NULL);
1238 gst_structure_set ((GstStructure *) klass->metadata,
1239 key, G_TYPE_STRING, value, NULL);
1243 * gst_element_class_add_static_metadata:
1244 * @klass: class to set metadata for
1245 * @key: the key to set
1246 * @value: the value to set
1248 * Set @key with @value as metadata in @klass.
1250 * Same as gst_element_class_add_metadata(), but @value must be a static string
1251 * or an inlined string, as it will not be copied. (GStreamer plugins will
1252 * be made resident once loaded, so this function can be used even from
1253 * dynamically loaded plugins.)
1256 gst_element_class_add_static_metadata (GstElementClass * klass,
1257 const gchar * key, const gchar * value)
1259 GValue val = G_VALUE_INIT;
1261 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1262 g_return_if_fail (key != NULL);
1263 g_return_if_fail (value != NULL);
1265 g_value_init (&val, G_TYPE_STRING);
1266 g_value_set_static_string (&val, value);
1267 gst_structure_take_value ((GstStructure *) klass->metadata, key, &val);
1271 * gst_element_class_set_metadata:
1272 * @klass: class to set metadata for
1273 * @longname: The long English name of the element. E.g. "File Sink"
1274 * @classification: String describing the type of element, as an unordered list
1275 * separated with slashes ('/'). See draft-klass.txt of the design docs
1276 * for more details and common types. E.g: "Sink/File"
1277 * @description: Sentence describing the purpose of the element.
1278 * E.g: "Write stream to a file"
1279 * @author: Name and contact details of the author(s). Use \n to separate
1280 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1282 * Sets the detailed information for a #GstElementClass.
1283 * <note>This function is for use in _class_init functions only.</note>
1286 gst_element_class_set_metadata (GstElementClass * klass,
1287 const gchar * longname, const gchar * classification,
1288 const gchar * description, const gchar * author)
1290 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1291 g_return_if_fail (longname != NULL && *longname != '\0');
1292 g_return_if_fail (classification != NULL && *classification != '\0');
1293 g_return_if_fail (description != NULL && *description != '\0');
1294 g_return_if_fail (author != NULL && *author != '\0');
1296 gst_structure_id_set ((GstStructure *) klass->metadata,
1297 GST_QUARK (ELEMENT_METADATA_LONGNAME), G_TYPE_STRING, longname,
1298 GST_QUARK (ELEMENT_METADATA_KLASS), G_TYPE_STRING, classification,
1299 GST_QUARK (ELEMENT_METADATA_DESCRIPTION), G_TYPE_STRING, description,
1300 GST_QUARK (ELEMENT_METADATA_AUTHOR), G_TYPE_STRING, author, NULL);
1304 * gst_element_class_set_static_metadata:
1305 * @klass: class to set metadata for
1306 * @longname: The long English name of the element. E.g. "File Sink"
1307 * @classification: String describing the type of element, as an unordered list
1308 * separated with slashes ('/'). See draft-klass.txt of the design docs
1309 * for more details and common types. E.g: "Sink/File"
1310 * @description: Sentence describing the purpose of the element.
1311 * E.g: "Write stream to a file"
1312 * @author: Name and contact details of the author(s). Use \n to separate
1313 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1315 * Sets the detailed information for a #GstElementClass.
1316 * <note>This function is for use in _class_init functions only.</note>
1318 * Same as gst_element_class_set_metadata(), but @longname, @classification,
1319 * @description, and @author must be static strings or inlined strings, as
1320 * they will not be copied. (GStreamer plugins will be made resident once
1321 * loaded, so this function can be used even from dynamically loaded plugins.)
1324 gst_element_class_set_static_metadata (GstElementClass * klass,
1325 const gchar * longname, const gchar * classification,
1326 const gchar * description, const gchar * author)
1328 GstStructure *s = (GstStructure *) klass->metadata;
1329 GValue val = G_VALUE_INIT;
1331 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1332 g_return_if_fail (longname != NULL && *longname != '\0');
1333 g_return_if_fail (classification != NULL && *classification != '\0');
1334 g_return_if_fail (description != NULL && *description != '\0');
1335 g_return_if_fail (author != NULL && *author != '\0');
1337 g_value_init (&val, G_TYPE_STRING);
1339 g_value_set_static_string (&val, longname);
1340 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_LONGNAME), &val);
1342 g_value_set_static_string (&val, classification);
1343 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_KLASS), &val);
1345 g_value_set_static_string (&val, description);
1346 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_DESCRIPTION),
1349 g_value_set_static_string (&val, author);
1350 gst_structure_id_take_value (s, GST_QUARK (ELEMENT_METADATA_AUTHOR), &val);
1354 * gst_element_class_get_metadata:
1355 * @klass: class to get metadata for
1356 * @key: the key to get
1358 * Get metadata with @key in @klass.
1360 * Returns: the metadata for @key.
1363 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1365 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1366 g_return_val_if_fail (key != NULL, NULL);
1368 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1372 * gst_element_class_get_pad_template_list:
1373 * @element_class: a #GstElementClass to get pad templates of.
1375 * Retrieves a list of the pad templates associated with @element_class. The
1376 * list must not be modified by the calling code.
1377 * <note>If you use this function in the #GInstanceInitFunc of an object class
1378 * that has subclasses, make sure to pass the g_class parameter of the
1379 * #GInstanceInitFunc here.</note>
1381 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1385 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1387 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1389 return element_class->padtemplates;
1393 * gst_element_class_get_pad_template:
1394 * @element_class: a #GstElementClass to get the pad template of.
1395 * @name: the name of the #GstPadTemplate to get.
1397 * Retrieves a padtemplate from @element_class with the given name.
1398 * <note>If you use this function in the #GInstanceInitFunc of an object class
1399 * that has subclasses, make sure to pass the g_class parameter of the
1400 * #GInstanceInitFunc here.</note>
1402 * Returns: (transfer none) (nullable): the #GstPadTemplate with the
1403 * given name, or %NULL if none was found. No unreferencing is
1407 gst_element_class_get_pad_template (GstElementClass *
1408 element_class, const gchar * name)
1412 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1413 g_return_val_if_fail (name != NULL, NULL);
1415 padlist = element_class->padtemplates;
1418 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1420 if (strcmp (padtempl->name_template, name) == 0)
1423 padlist = g_list_next (padlist);
1429 static GstPadTemplate *
1430 gst_element_class_get_request_pad_template (GstElementClass *
1431 element_class, const gchar * name)
1433 GstPadTemplate *tmpl;
1435 tmpl = gst_element_class_get_pad_template (element_class, name);
1436 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1442 /* get a random pad on element of the given direction.
1443 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1446 gst_element_get_random_pad (GstElement * element,
1447 gboolean need_linked, GstPadDirection dir)
1449 GstPad *result = NULL;
1452 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1456 GST_OBJECT_LOCK (element);
1457 pads = element->srcpads;
1460 GST_OBJECT_LOCK (element);
1461 pads = element->sinkpads;
1464 goto wrong_direction;
1466 for (; pads; pads = g_list_next (pads)) {
1467 GstPad *pad = GST_PAD_CAST (pads->data);
1469 GST_OBJECT_LOCK (pad);
1470 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1471 GST_DEBUG_PAD_NAME (pad));
1473 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1474 /* if we require a linked pad, and it is not linked, continue the
1476 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1477 GST_DEBUG_PAD_NAME (pad));
1478 GST_OBJECT_UNLOCK (pad);
1481 /* found a pad, stop search */
1482 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1483 GST_DEBUG_PAD_NAME (pad));
1484 GST_OBJECT_UNLOCK (pad);
1490 gst_object_ref (result);
1492 GST_OBJECT_UNLOCK (element);
1496 /* ERROR handling */
1499 g_warning ("unknown pad direction %d", dir);
1505 gst_element_default_send_event (GstElement * element, GstEvent * event)
1507 gboolean result = FALSE;
1510 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1511 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK) :
1512 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC);
1515 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1516 "pushing %s event to random %s pad %s:%s",
1517 GST_EVENT_TYPE_NAME (event),
1518 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1519 GST_DEBUG_PAD_NAME (pad));
1521 result = gst_pad_send_event (pad, event);
1522 gst_object_unref (pad);
1524 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1525 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1526 gst_event_unref (event);
1532 * gst_element_send_event:
1533 * @element: a #GstElement to send the event to.
1534 * @event: (transfer full): the #GstEvent to send to the element.
1536 * Sends an event to an element. If the element doesn't implement an
1537 * event handler, the event will be pushed on a random linked sink pad for
1538 * downstream events or a random linked source pad for upstream events.
1540 * This function takes ownership of the provided event so you should
1541 * gst_event_ref() it if you want to reuse the event after this call.
1545 * Returns: %TRUE if the event was handled. Events that trigger a preroll (such
1546 * as flushing seeks and steps) will emit %GST_MESSAGE_ASYNC_DONE.
1549 gst_element_send_event (GstElement * element, GstEvent * event)
1551 GstElementClass *oclass;
1552 gboolean result = FALSE;
1554 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1555 g_return_val_if_fail (event != NULL, FALSE);
1557 oclass = GST_ELEMENT_GET_CLASS (element);
1559 GST_STATE_LOCK (element);
1560 if (oclass->send_event) {
1561 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1562 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1563 result = oclass->send_event (element, event);
1565 GST_STATE_UNLOCK (element);
1572 * @element: a #GstElement to send the event to.
1573 * @rate: The new playback rate
1574 * @format: The format of the seek values
1575 * @flags: The optional seek flags.
1576 * @start_type: The type and flags for the new start position
1577 * @start: The value of the new start position
1578 * @stop_type: The type and flags for the new stop position
1579 * @stop: The value of the new stop position
1581 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1582 * the parameters. The seek event is sent to the element using
1583 * gst_element_send_event().
1587 * Returns: %TRUE if the event was handled. Flushing seeks will trigger a
1588 * preroll, which will emit %GST_MESSAGE_ASYNC_DONE.
1591 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1592 GstSeekFlags flags, GstSeekType start_type, gint64 start,
1593 GstSeekType stop_type, gint64 stop)
1598 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1601 gst_event_new_seek (rate, format, flags, start_type, start, stop_type,
1603 result = gst_element_send_event (element, event);
1609 gst_element_default_query (GstElement * element, GstQuery * query)
1611 gboolean result = FALSE;
1614 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1616 result = gst_pad_query (pad, query);
1618 gst_object_unref (pad);
1620 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1622 GstPad *peer = gst_pad_get_peer (pad);
1625 result = gst_pad_query (peer, query);
1627 gst_object_unref (peer);
1629 gst_object_unref (pad);
1636 * gst_element_query:
1637 * @element: a #GstElement to perform the query on.
1638 * @query: (transfer none): the #GstQuery.
1640 * Performs a query on the given element.
1642 * For elements that don't implement a query handler, this function
1643 * forwards the query to a random srcpad or to the peer of a
1644 * random linked sinkpad of this element.
1646 * Please note that some queries might need a running pipeline to work.
1648 * Returns: %TRUE if the query could be performed.
1653 gst_element_query (GstElement * element, GstQuery * query)
1655 GstElementClass *klass;
1657 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1658 g_return_val_if_fail (query != NULL, FALSE);
1660 klass = GST_ELEMENT_GET_CLASS (element);
1662 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1663 GST_ELEMENT_NAME (element));
1664 return klass->query (element, query);
1671 gst_element_post_message_default (GstElement * element, GstMessage * message)
1674 gboolean result = FALSE;
1676 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1677 g_return_val_if_fail (message != NULL, FALSE);
1679 GST_OBJECT_LOCK (element);
1682 if (G_UNLIKELY (bus == NULL))
1685 gst_object_ref (bus);
1686 GST_OBJECT_UNLOCK (element);
1688 /* we release the element lock when posting the message so that any
1689 * (synchronous) message handlers can operate on the element */
1690 result = gst_bus_post (bus, message);
1691 gst_object_unref (bus);
1698 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1699 "not posting message %p: no bus", message);
1700 GST_OBJECT_UNLOCK (element);
1701 gst_message_unref (message);
1707 * gst_element_post_message:
1708 * @element: a #GstElement posting the message
1709 * @message: (transfer full): a #GstMessage to post
1711 * Post a message on the element's #GstBus. This function takes ownership of the
1712 * message; if you want to access the message after this call, you should add an
1713 * additional reference before calling.
1715 * Returns: %TRUE if the message was successfully posted. The function returns
1716 * %FALSE if the element did not have a bus.
1721 gst_element_post_message (GstElement * element, GstMessage * message)
1723 GstElementClass *klass;
1725 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1726 g_return_val_if_fail (message != NULL, FALSE);
1728 klass = GST_ELEMENT_GET_CLASS (element);
1729 if (klass->post_message)
1730 return klass->post_message (element, message);
1736 * _gst_element_error_printf:
1737 * @format: (allow-none): the printf-like format to use, or %NULL
1739 * This function is only used internally by the gst_element_error() macro.
1741 * Returns: (transfer full) (nullable): a newly allocated string, or
1742 * %NULL if the format was %NULL or ""
1747 _gst_element_error_printf (const gchar * format, ...)
1758 va_start (args, format);
1760 len = __gst_vasprintf (&buffer, format, args);
1771 * gst_element_message_full:
1772 * @element: a #GstElement to send message from
1773 * @type: the #GstMessageType
1774 * @domain: the GStreamer GError domain this message belongs to
1775 * @code: the GError code belonging to the domain
1776 * @text: (allow-none) (transfer full): an allocated text string to be used
1777 * as a replacement for the default message connected to code,
1779 * @debug: (allow-none) (transfer full): an allocated debug message to be
1780 * used as a replacement for the default debugging information,
1782 * @file: the source code file where the error was generated
1783 * @function: the source code function where the error was generated
1784 * @line: the source code line where the error was generated
1786 * Post an error, warning or info message on the bus from inside an element.
1788 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1789 * #GST_MESSAGE_INFO.
1793 void gst_element_message_full
1794 (GstElement * element, GstMessageType type,
1795 GQuark domain, gint code, gchar * text,
1796 gchar * debug, const gchar * file, const gchar * function, gint line)
1798 GError *gerror = NULL;
1802 gboolean has_debug = TRUE;
1803 GstMessage *message = NULL;
1806 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1807 g_return_if_fail (GST_IS_ELEMENT (element));
1808 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1809 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1811 /* check if we send the given text or the default error text */
1812 if ((text == NULL) || (text[0] == 0)) {
1813 /* text could have come from g_strdup_printf (""); */
1815 sent_text = gst_error_get_message (domain, code);
1819 /* construct a sent_debug with extra information from source */
1820 if ((debug == NULL) || (debug[0] == 0)) {
1821 /* debug could have come from g_strdup_printf (""); */
1825 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1827 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1828 file, line, function, name, debug);
1830 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1831 file, line, function, name);
1835 /* create gerror and post message */
1836 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1838 gerror = g_error_new_literal (domain, code, sent_text);
1841 case GST_MESSAGE_ERROR:
1843 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1845 case GST_MESSAGE_WARNING:
1846 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1849 case GST_MESSAGE_INFO:
1850 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1854 g_assert_not_reached ();
1857 gst_element_post_message (element, message);
1859 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1860 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1863 g_error_free (gerror);
1864 g_free (sent_debug);
1869 * gst_element_is_locked_state:
1870 * @element: a #GstElement.
1872 * Checks if the state of an element is locked.
1873 * If the state of an element is locked, state changes of the parent don't
1874 * affect the element.
1875 * This way you can leave currently unused elements inside bins. Just lock their
1876 * state before changing the state from #GST_STATE_NULL.
1880 * Returns: %TRUE, if the element's state is locked.
1883 gst_element_is_locked_state (GstElement * element)
1887 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1889 GST_OBJECT_LOCK (element);
1890 result = GST_ELEMENT_IS_LOCKED_STATE (element);
1891 GST_OBJECT_UNLOCK (element);
1897 * gst_element_set_locked_state:
1898 * @element: a #GstElement
1899 * @locked_state: %TRUE to lock the element's state
1901 * Locks the state of an element, so state changes of the parent don't affect
1902 * this element anymore.
1906 * Returns: %TRUE if the state was changed, %FALSE if bad parameters were given
1907 * or the elements state-locking needed no change.
1910 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1914 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1916 GST_OBJECT_LOCK (element);
1917 old = GST_ELEMENT_IS_LOCKED_STATE (element);
1919 if (G_UNLIKELY (old == locked_state))
1923 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1924 GST_ELEMENT_NAME (element));
1925 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1927 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1928 GST_ELEMENT_NAME (element));
1929 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1931 GST_OBJECT_UNLOCK (element);
1937 GST_CAT_DEBUG (GST_CAT_STATES,
1938 "elements %s was already in locked state %d",
1939 GST_ELEMENT_NAME (element), old);
1940 GST_OBJECT_UNLOCK (element);
1947 * gst_element_sync_state_with_parent:
1948 * @element: a #GstElement.
1950 * Tries to change the state of the element to the same as its parent.
1951 * If this function returns %FALSE, the state of element is undefined.
1953 * Returns: %TRUE, if the element's state could be synced to the parent's state.
1958 gst_element_sync_state_with_parent (GstElement * element)
1962 GstStateChangeReturn ret;
1964 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1966 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1967 GstState parent_current, parent_pending;
1969 GST_OBJECT_LOCK (parent);
1970 parent_current = GST_STATE (parent);
1971 parent_pending = GST_STATE_PENDING (parent);
1972 GST_OBJECT_UNLOCK (parent);
1974 /* set to pending if there is one, else we set it to the current state of
1976 if (parent_pending != GST_STATE_VOID_PENDING)
1977 target = parent_pending;
1979 target = parent_current;
1981 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1982 "syncing state (%s) to parent %s %s (%s, %s)",
1983 gst_element_state_get_name (GST_STATE (element)),
1984 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1985 gst_element_state_get_name (parent_current),
1986 gst_element_state_get_name (parent_pending));
1988 ret = gst_element_set_state (element, target);
1989 if (ret == GST_STATE_CHANGE_FAILURE)
1992 gst_object_unref (parent);
1996 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
2003 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2004 "syncing state failed (%s)",
2005 gst_element_state_change_return_get_name (ret));
2006 gst_object_unref (parent);
2012 static GstStateChangeReturn
2013 gst_element_get_state_func (GstElement * element,
2014 GstState * state, GstState * pending, GstClockTime timeout)
2016 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2017 GstState old_pending;
2019 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2020 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2022 GST_OBJECT_LOCK (element);
2023 ret = GST_STATE_RETURN (element);
2024 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2025 gst_element_state_change_return_get_name (ret));
2027 /* we got an error, report immediately */
2028 if (ret == GST_STATE_CHANGE_FAILURE)
2031 /* we got no_preroll, report immediately */
2032 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2035 /* no need to wait async if we are not async */
2036 if (ret != GST_STATE_CHANGE_ASYNC)
2039 old_pending = GST_STATE_PENDING (element);
2040 if (old_pending != GST_STATE_VOID_PENDING) {
2044 /* get cookie to detect state changes during waiting */
2045 cookie = element->state_cookie;
2047 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2048 "waiting for element to commit state");
2050 /* we have a pending state change, wait for it to complete */
2051 if (timeout != GST_CLOCK_TIME_NONE) {
2053 /* make timeout absolute */
2054 end_time = g_get_monotonic_time () + (timeout / 1000);
2055 signaled = GST_STATE_WAIT_UNTIL (element, end_time);
2057 GST_STATE_WAIT (element);
2062 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2063 /* timeout triggered */
2064 ret = GST_STATE_CHANGE_ASYNC;
2066 if (cookie != element->state_cookie)
2069 /* could be success or failure */
2070 if (old_pending == GST_STATE (element)) {
2071 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2072 ret = GST_STATE_CHANGE_SUCCESS;
2074 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2075 ret = GST_STATE_CHANGE_FAILURE;
2078 /* if nothing is pending anymore we can return SUCCESS */
2079 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2080 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2081 ret = GST_STATE_CHANGE_SUCCESS;
2087 *state = GST_STATE (element);
2089 *pending = GST_STATE_PENDING (element);
2091 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2092 "state current: %s, pending: %s, result: %s",
2093 gst_element_state_get_name (GST_STATE (element)),
2094 gst_element_state_get_name (GST_STATE_PENDING (element)),
2095 gst_element_state_change_return_get_name (ret));
2096 GST_OBJECT_UNLOCK (element);
2103 *state = GST_STATE_VOID_PENDING;
2105 *pending = GST_STATE_VOID_PENDING;
2107 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2109 GST_OBJECT_UNLOCK (element);
2111 return GST_STATE_CHANGE_FAILURE;
2116 * gst_element_get_state:
2117 * @element: a #GstElement to get the state of.
2118 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2120 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2121 * state. Can be %NULL.
2122 * @timeout: a #GstClockTime to specify the timeout for an async
2123 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2125 * Gets the state of the element.
2127 * For elements that performed an ASYNC state change, as reported by
2128 * gst_element_set_state(), this function will block up to the
2129 * specified timeout value for the state change to complete.
2130 * If the element completes the state change or goes into
2131 * an error, this function returns immediately with a return value of
2132 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2134 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2135 * returns the current and pending state immediately.
2137 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2138 * successfully changed its state but is not able to provide data yet.
2139 * This mostly happens for live sources that only produce data in
2140 * %GST_STATE_PLAYING. While the state change return is equivalent to
2141 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2142 * some sink elements might not be able to complete their state change because
2143 * an element is not producing data to complete the preroll. When setting the
2144 * element to playing, the preroll will complete and playback will start.
2146 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2147 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2148 * element is still performing a state change or
2149 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2153 GstStateChangeReturn
2154 gst_element_get_state (GstElement * element,
2155 GstState * state, GstState * pending, GstClockTime timeout)
2157 GstElementClass *oclass;
2158 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2160 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2162 oclass = GST_ELEMENT_GET_CLASS (element);
2164 if (oclass->get_state)
2165 result = (oclass->get_state) (element, state, pending, timeout);
2171 * gst_element_abort_state:
2172 * @element: a #GstElement to abort the state of.
2174 * Abort the state change of the element. This function is used
2175 * by elements that do asynchronous state changes and find out
2176 * something is wrong.
2178 * This function should be called with the STATE_LOCK held.
2183 gst_element_abort_state (GstElement * element)
2187 #ifndef GST_DISABLE_GST_DEBUG
2191 g_return_if_fail (GST_IS_ELEMENT (element));
2193 GST_OBJECT_LOCK (element);
2194 pending = GST_STATE_PENDING (element);
2196 if (pending == GST_STATE_VOID_PENDING ||
2197 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2198 goto nothing_aborted;
2200 #ifndef GST_DISABLE_GST_DEBUG
2201 old_state = GST_STATE (element);
2203 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2204 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2205 gst_element_state_get_name (pending));
2209 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2211 GST_STATE_BROADCAST (element);
2212 GST_OBJECT_UNLOCK (element);
2218 GST_OBJECT_UNLOCK (element);
2223 /* Not static because GstBin has manual state handling too */
2225 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2226 GstState newstate, GstState pending)
2228 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2229 GstMessage *message;
2231 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2232 "notifying about state-changed %s to %s (%s pending)",
2233 gst_element_state_get_name (oldstate),
2234 gst_element_state_get_name (newstate),
2235 gst_element_state_get_name (pending));
2237 if (klass->state_changed)
2238 klass->state_changed (element, oldstate, newstate, pending);
2240 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2241 oldstate, newstate, pending);
2242 gst_element_post_message (element, message);
2246 * gst_element_continue_state:
2247 * @element: a #GstElement to continue the state change of.
2248 * @ret: The previous state return value
2250 * Commit the state change of the element and proceed to the next
2251 * pending state if any. This function is used
2252 * by elements that do asynchronous state changes.
2253 * The core will normally call this method automatically when an
2254 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2256 * If after calling this method the element still has not reached
2257 * the pending state, the next state change is performed.
2259 * This method is used internally and should normally not be called by plugins
2262 * Returns: The result of the commit state change.
2266 GstStateChangeReturn
2267 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2269 GstStateChangeReturn old_ret;
2270 GstState old_state, old_next;
2271 GstState current, next, pending;
2272 GstStateChange transition;
2274 GST_OBJECT_LOCK (element);
2275 old_ret = GST_STATE_RETURN (element);
2276 GST_STATE_RETURN (element) = ret;
2277 pending = GST_STATE_PENDING (element);
2279 /* check if there is something to commit */
2280 if (pending == GST_STATE_VOID_PENDING)
2281 goto nothing_pending;
2283 old_state = GST_STATE (element);
2284 /* this is the state we should go to next */
2285 old_next = GST_STATE_NEXT (element);
2286 /* update current state */
2287 current = GST_STATE (element) = old_next;
2289 /* see if we reached the final state */
2290 if (pending == current)
2293 next = GST_STATE_GET_NEXT (current, pending);
2294 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2296 GST_STATE_NEXT (element) = next;
2298 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2299 GST_OBJECT_UNLOCK (element);
2301 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2302 "committing state from %s to %s, pending %s, next %s",
2303 gst_element_state_get_name (old_state),
2304 gst_element_state_get_name (old_next),
2305 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2307 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2309 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2310 "continue state change %s to %s, final %s",
2311 gst_element_state_get_name (current),
2312 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2314 ret = gst_element_change_state (element, transition);
2320 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2321 GST_OBJECT_UNLOCK (element);
2326 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2327 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2329 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2330 "completed state change to %s", gst_element_state_get_name (pending));
2331 GST_OBJECT_UNLOCK (element);
2333 /* don't post silly messages with the same state. This can happen
2334 * when an element state is changed to what it already was. For bins
2335 * this can be the result of a lost state, which we check with the
2336 * previous return value.
2337 * We do signal the cond though as a _get_state() might be blocking
2339 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2340 _priv_gst_element_state_changed (element, old_state, old_next,
2341 GST_STATE_VOID_PENDING);
2343 GST_STATE_BROADCAST (element);
2350 * gst_element_lost_state:
2351 * @element: a #GstElement the state is lost of
2353 * Brings the element to the lost state. The current state of the
2354 * element is copied to the pending state so that any call to
2355 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2357 * An ASYNC_START message is posted. If the element was PLAYING, it will
2358 * go to PAUSED. The element will be restored to its PLAYING state by
2359 * the parent pipeline when it prerolls again.
2361 * This is mostly used for elements that lost their preroll buffer
2362 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2363 * they will go to their pending state again when a new preroll buffer is
2364 * queued. This function can only be called when the element is currently
2365 * not in error or an async state change.
2367 * This function is used internally and should normally not be called from
2368 * plugins or applications.
2371 gst_element_lost_state (GstElement * element)
2373 GstState old_state, new_state;
2374 GstMessage *message;
2376 g_return_if_fail (GST_IS_ELEMENT (element));
2378 GST_OBJECT_LOCK (element);
2379 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2382 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2383 goto only_async_start;
2385 old_state = GST_STATE (element);
2387 /* when we were PLAYING, the new state is PAUSED. We will also not
2388 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2389 * when we preroll. */
2390 if (old_state > GST_STATE_PAUSED)
2391 new_state = GST_STATE_PAUSED;
2393 new_state = old_state;
2395 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2396 "lost state of %s to %s", gst_element_state_get_name (old_state),
2397 gst_element_state_get_name (new_state));
2399 GST_STATE (element) = new_state;
2400 GST_STATE_NEXT (element) = new_state;
2401 GST_STATE_PENDING (element) = new_state;
2402 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2403 GST_OBJECT_UNLOCK (element);
2405 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2407 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2408 gst_element_post_message (element, message);
2414 GST_OBJECT_UNLOCK (element);
2419 GST_OBJECT_UNLOCK (element);
2421 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2422 gst_element_post_message (element, message);
2428 * gst_element_set_state:
2429 * @element: a #GstElement to change state of.
2430 * @state: the element's new #GstState.
2432 * Sets the state of the element. This function will try to set the
2433 * requested state by going through all the intermediary states and calling
2434 * the class's state change function for each.
2436 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2437 * element will perform the remainder of the state change asynchronously in
2439 * An application can use gst_element_get_state() to wait for the completion
2440 * of the state change or it can wait for a %GST_MESSAGE_ASYNC_DONE or
2441 * %GST_MESSAGE_STATE_CHANGED on the bus.
2443 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2444 * #GST_STATE_CHANGE_ASYNC.
2446 * Returns: Result of the state change using #GstStateChangeReturn.
2450 GstStateChangeReturn
2451 gst_element_set_state (GstElement * element, GstState state)
2453 GstElementClass *oclass;
2454 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2456 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2458 oclass = GST_ELEMENT_GET_CLASS (element);
2460 if (oclass->set_state)
2461 result = (oclass->set_state) (element, state);
2467 * default set state function, calculates the next state based
2468 * on current state and calls the change_state function
2470 static GstStateChangeReturn
2471 gst_element_set_state_func (GstElement * element, GstState state)
2473 GstState current, next, old_pending;
2474 GstStateChangeReturn ret;
2475 GstStateChange transition;
2476 GstStateChangeReturn old_ret;
2478 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2480 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2481 gst_element_state_get_name (state));
2483 /* state lock is taken to protect the set_state() and get_state()
2484 * procedures, it does not lock any variables. */
2485 GST_STATE_LOCK (element);
2487 /* now calculate how to get to the new state */
2488 GST_OBJECT_LOCK (element);
2489 old_ret = GST_STATE_RETURN (element);
2490 /* previous state change returned an error, remove all pending
2491 * and next states */
2492 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2493 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2494 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2495 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2498 current = GST_STATE (element);
2499 next = GST_STATE_NEXT (element);
2500 old_pending = GST_STATE_PENDING (element);
2502 /* this is the (new) state we should go to. TARGET is the last state we set on
2504 if (state != GST_STATE_TARGET (element)) {
2505 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2506 "setting target state to %s", gst_element_state_get_name (state));
2507 GST_STATE_TARGET (element) = state;
2508 /* increment state cookie so that we can track each state change. We only do
2509 * this if this is actually a new state change. */
2510 element->state_cookie++;
2512 GST_STATE_PENDING (element) = state;
2514 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2515 "current %s, old_pending %s, next %s, old return %s",
2516 gst_element_state_get_name (current),
2517 gst_element_state_get_name (old_pending),
2518 gst_element_state_get_name (next),
2519 gst_element_state_change_return_get_name (old_ret));
2521 /* if the element was busy doing a state change, we just update the
2522 * target state, it'll get to it async then. */
2523 if (old_pending != GST_STATE_VOID_PENDING) {
2524 /* upwards state change will happen ASYNC */
2525 if (old_pending <= state)
2527 /* element is going to this state already */
2528 else if (next == state)
2530 /* element was performing an ASYNC upward state change and
2531 * we request to go downward again. Start from the next pending
2533 else if (next > state
2534 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2538 next = GST_STATE_GET_NEXT (current, state);
2539 /* now we store the next state */
2540 GST_STATE_NEXT (element) = next;
2541 /* mark busy, we need to check that there is actually a state change
2542 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2543 * the default element change_state function has no way to know what the
2544 * old value was... could consider this a FIXME...*/
2545 if (current != next)
2546 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2548 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2550 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2551 "%s: setting state from %s to %s",
2552 (next != state ? "intermediate" : "final"),
2553 gst_element_state_get_name (current), gst_element_state_get_name (next));
2555 /* now signal any waiters, they will error since the cookie was incremented */
2556 GST_STATE_BROADCAST (element);
2558 GST_OBJECT_UNLOCK (element);
2560 ret = gst_element_change_state (element, transition);
2562 GST_STATE_UNLOCK (element);
2564 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2565 gst_element_state_change_return_get_name (ret));
2571 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2572 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2573 "element was busy with async state change");
2574 GST_OBJECT_UNLOCK (element);
2576 GST_STATE_UNLOCK (element);
2578 return GST_STATE_CHANGE_ASYNC;
2583 * gst_element_change_state:
2584 * @element: a #GstElement
2585 * @transition: the requested transition
2587 * Perform @transition on @element.
2589 * This function must be called with STATE_LOCK held and is mainly used
2592 * Returns: the #GstStateChangeReturn of the state transition.
2594 GstStateChangeReturn
2595 gst_element_change_state (GstElement * element, GstStateChange transition)
2597 GstElementClass *oclass;
2598 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2600 oclass = GST_ELEMENT_GET_CLASS (element);
2602 /* call the state change function so it can set the state */
2603 if (oclass->change_state)
2604 ret = (oclass->change_state) (element, transition);
2606 ret = GST_STATE_CHANGE_FAILURE;
2609 case GST_STATE_CHANGE_FAILURE:
2610 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2611 "have FAILURE change_state return");
2612 /* state change failure */
2613 gst_element_abort_state (element);
2615 case GST_STATE_CHANGE_ASYNC:
2619 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2620 "element will change state ASYNC");
2622 target = GST_STATE_TARGET (element);
2624 if (target > GST_STATE_READY)
2627 /* else we just continue the state change downwards */
2628 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2629 "forcing commit state %s <= %s",
2630 gst_element_state_get_name (target),
2631 gst_element_state_get_name (GST_STATE_READY));
2633 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2636 case GST_STATE_CHANGE_SUCCESS:
2637 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2638 "element changed state SUCCESS");
2639 /* we can commit the state now which will proceeed to
2641 ret = gst_element_continue_state (element, ret);
2643 case GST_STATE_CHANGE_NO_PREROLL:
2644 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2645 "element changed state NO_PREROLL");
2646 /* we can commit the state now which will proceeed to
2648 ret = gst_element_continue_state (element, ret);
2651 goto invalid_return;
2654 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2659 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2667 GST_OBJECT_LOCK (element);
2668 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2669 g_critical ("%s: unknown return value %d from a state change function",
2670 GST_ELEMENT_NAME (element), ret);
2672 /* we are in error now */
2673 ret = GST_STATE_CHANGE_FAILURE;
2674 GST_STATE_RETURN (element) = ret;
2675 GST_OBJECT_UNLOCK (element);
2681 /* gst_iterator_fold functions for pads_activate
2682 * Stop the iterator if activating one pad failed, but only if that pad
2683 * has not been removed from the element. */
2685 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2687 GstPad *pad = g_value_get_object (vpad);
2688 gboolean cont = TRUE;
2690 if (!gst_pad_set_active (pad, *active)) {
2691 if (GST_PAD_PARENT (pad) != NULL) {
2693 g_value_set_boolean (ret, FALSE);
2700 /* returns false on error or early cutout of the fold, true if all
2701 * pads in @iter were (de)activated successfully. */
2703 iterator_activate_fold_with_resync (GstIterator * iter,
2704 GstIteratorFoldFunction func, gpointer user_data)
2706 GstIteratorResult ires;
2709 /* no need to unset this later, it's just a boolean */
2710 g_value_init (&ret, G_TYPE_BOOLEAN);
2711 g_value_set_boolean (&ret, TRUE);
2714 ires = gst_iterator_fold (iter, func, &ret, user_data);
2716 case GST_ITERATOR_RESYNC:
2717 /* need to reset the result again */
2718 g_value_set_boolean (&ret, TRUE);
2719 gst_iterator_resync (iter);
2721 case GST_ITERATOR_DONE:
2722 /* all pads iterated, return collected value */
2725 /* iterator returned _ERROR or premature end with _OK,
2726 * mark an error and exit */
2727 g_value_set_boolean (&ret, FALSE);
2732 /* return collected value */
2733 return g_value_get_boolean (&ret);
2736 /* is called with STATE_LOCK
2738 * Pads are activated from source pads to sinkpads.
2741 gst_element_pads_activate (GstElement * element, gboolean active)
2746 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2747 "%s pads", active ? "activate" : "deactivate");
2749 iter = gst_element_iterate_src_pads (element);
2751 iterator_activate_fold_with_resync (iter,
2752 (GstIteratorFoldFunction) activate_pads, &active);
2753 gst_iterator_free (iter);
2754 if (G_UNLIKELY (!res))
2757 iter = gst_element_iterate_sink_pads (element);
2759 iterator_activate_fold_with_resync (iter,
2760 (GstIteratorFoldFunction) activate_pads, &active);
2761 gst_iterator_free (iter);
2762 if (G_UNLIKELY (!res))
2765 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2766 "pad %sactivation successful", active ? "" : "de");
2773 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2774 "pad %sactivation failed", active ? "" : "de");
2779 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2780 "sink pads_activate failed");
2785 /* is called with STATE_LOCK */
2786 static GstStateChangeReturn
2787 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2789 GstState state, next;
2790 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2792 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2794 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2795 next = GST_STATE_TRANSITION_NEXT (transition);
2797 /* if the element already is in the given state, we just return success */
2798 if (next == GST_STATE_VOID_PENDING || state == next)
2801 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2802 "default handler tries setting state from %s to %s (%04x)",
2803 gst_element_state_get_name (state),
2804 gst_element_state_get_name (next), transition);
2806 switch (transition) {
2807 case GST_STATE_CHANGE_NULL_TO_READY:
2809 case GST_STATE_CHANGE_READY_TO_PAUSED:
2810 if (!gst_element_pads_activate (element, TRUE)) {
2811 result = GST_STATE_CHANGE_FAILURE;
2814 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2816 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2818 case GST_STATE_CHANGE_PAUSED_TO_READY:
2819 case GST_STATE_CHANGE_READY_TO_NULL:
2820 /* deactivate pads in both cases, since they are activated on
2821 ready->paused but the element might not have made it to paused */
2822 if (!gst_element_pads_activate (element, FALSE)) {
2823 result = GST_STATE_CHANGE_FAILURE;
2827 /* this will catch real but unhandled state changes;
2828 * can only be caused by:
2829 * - a new state was added
2830 * - somehow the element was asked to jump across an intermediate state
2832 g_warning ("Unhandled state change from %s to %s",
2833 gst_element_state_get_name (state),
2834 gst_element_state_get_name (next));
2841 GST_OBJECT_LOCK (element);
2842 result = GST_STATE_RETURN (element);
2843 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2844 "element is already in the %s state",
2845 gst_element_state_get_name (state));
2846 GST_OBJECT_UNLOCK (element);
2853 * gst_element_get_factory:
2854 * @element: a #GstElement to request the element factory of.
2856 * Retrieves the factory that was used to create this element.
2858 * Returns: (transfer none): the #GstElementFactory used for creating this
2859 * element. no refcounting is needed.
2862 gst_element_get_factory (GstElement * element)
2864 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2866 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2870 gst_element_dispose (GObject * object)
2872 GstElement *element = GST_ELEMENT_CAST (object);
2875 GstElementClass *oclass;
2878 oclass = GST_ELEMENT_GET_CLASS (element);
2880 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2882 if (GST_STATE (element) != GST_STATE_NULL)
2885 /* start by releasing all request pads, this might also remove some dynamic
2887 walk = element->pads;
2889 GstPad *pad = GST_PAD_CAST (walk->data);
2893 if (oclass->release_pad && GST_PAD_PAD_TEMPLATE (pad) &&
2894 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
2895 == GST_PAD_REQUEST) {
2896 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2897 "removing request pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2898 oclass->release_pad (element, pad);
2900 /* in case the release_pad function removed the next pad too */
2901 if (walk && g_list_position (element->pads, walk) == -1)
2902 walk = element->pads;
2905 /* remove the remaining pads */
2906 while (element->pads) {
2907 GstPad *pad = GST_PAD_CAST (element->pads->data);
2908 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2909 "removing pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2910 if (!gst_element_remove_pad (element, pad)) {
2911 /* only happens when someone unparented our pad.. */
2912 g_critical ("failed to remove pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2917 GST_OBJECT_LOCK (element);
2918 clock_p = &element->clock;
2919 bus_p = &element->bus;
2920 gst_object_replace ((GstObject **) clock_p, NULL);
2921 gst_object_replace ((GstObject **) bus_p, NULL);
2922 GST_OBJECT_UNLOCK (element);
2924 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2926 G_OBJECT_CLASS (parent_class)->dispose (object);
2935 is_locked = GST_ELEMENT_IS_LOCKED_STATE (element);
2937 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2939 "You need to explicitly set elements to the NULL state before\n"
2940 "dropping the final reference, to allow them to clean up.\n"
2941 "This problem may also be caused by a refcounting bug in the\n"
2942 "application or some element.\n",
2943 GST_OBJECT_NAME (element),
2944 gst_element_state_get_name (GST_STATE (element)),
2945 is_locked ? " (locked)" : "");
2951 gst_element_finalize (GObject * object)
2953 GstElement *element = GST_ELEMENT_CAST (object);
2955 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2957 g_cond_clear (&element->state_cond);
2958 g_rec_mutex_clear (&element->state_lock);
2960 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2962 G_OBJECT_CLASS (parent_class)->finalize (object);
2966 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2970 g_return_if_fail (GST_IS_ELEMENT (element));
2972 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2974 GST_OBJECT_LOCK (element);
2975 bus_p = &GST_ELEMENT_BUS (element);
2976 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
2977 GST_OBJECT_UNLOCK (element);
2981 * gst_element_set_bus:
2982 * @element: a #GstElement to set the bus of.
2983 * @bus: (transfer none): the #GstBus to set.
2985 * Sets the bus of the element. Increases the refcount on the bus.
2986 * For internal use only, unless you're testing elements.
2991 gst_element_set_bus (GstElement * element, GstBus * bus)
2993 GstElementClass *oclass;
2995 g_return_if_fail (GST_IS_ELEMENT (element));
2997 oclass = GST_ELEMENT_GET_CLASS (element);
2999 if (oclass->set_bus)
3000 oclass->set_bus (element, bus);
3004 * gst_element_get_bus:
3005 * @element: a #GstElement to get the bus of.
3007 * Returns the bus of the element. Note that only a #GstPipeline will provide a
3008 * bus for the application.
3010 * Returns: (transfer full): the element's #GstBus. unref after usage.
3015 gst_element_get_bus (GstElement * element)
3017 GstBus *result = NULL;
3019 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3021 GST_OBJECT_LOCK (element);
3022 if ((result = GST_ELEMENT_BUS (element)))
3023 gst_object_ref (result);
3024 GST_OBJECT_UNLOCK (element);
3026 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,
3033 * gst_element_set_context:
3034 * @element: a #GstElement to set the context of.
3035 * @context: (transfer none): the #GstContext to set.
3037 * Sets the context of the element. Increases the refcount of the context.
3042 gst_element_set_context (GstElement * element, GstContext * context)
3044 GstElementClass *oclass;
3046 g_return_if_fail (GST_IS_ELEMENT (element));
3048 oclass = GST_ELEMENT_GET_CLASS (element);
3050 GST_CAT_DEBUG_OBJECT (GST_CAT_CONTEXT, element,
3051 "set context %p %" GST_PTR_FORMAT, context,
3052 gst_context_get_structure (context));
3054 if (oclass->set_context)
3055 oclass->set_context (element, context);