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 * Returns: (transfer full): the #GstClock of the element. unref after usage.
425 gst_element_get_clock (GstElement * element)
429 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
431 GST_OBJECT_LOCK (element);
432 if ((result = element->clock))
433 gst_object_ref (result);
434 GST_OBJECT_UNLOCK (element);
440 * gst_element_set_base_time:
441 * @element: a #GstElement.
442 * @time: the base time to set.
444 * Set the base time of an element. See gst_element_get_base_time().
449 gst_element_set_base_time (GstElement * element, GstClockTime time)
453 g_return_if_fail (GST_IS_ELEMENT (element));
455 GST_OBJECT_LOCK (element);
456 old = element->base_time;
457 element->base_time = time;
458 GST_OBJECT_UNLOCK (element);
460 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
461 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
462 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
466 * gst_element_get_base_time:
467 * @element: a #GstElement.
469 * Returns the base time of the element. The base time is the
470 * absolute time of the clock when this element was last put to
471 * PLAYING. Subtracting the base time from the clock time gives
472 * the running time of the element.
474 * Returns: the base time of the element.
479 gst_element_get_base_time (GstElement * element)
483 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
485 GST_OBJECT_LOCK (element);
486 result = element->base_time;
487 GST_OBJECT_UNLOCK (element);
493 * gst_element_set_start_time:
494 * @element: a #GstElement.
495 * @time: the base time to set.
497 * Set the start time of an element. The start time of the element is the
498 * running time of the element when it last went to the PAUSED state. In READY
499 * or after a flushing seek, it is set to 0.
501 * Toplevel elements like #GstPipeline will manage the start_time and
502 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
503 * on such a toplevel element will disable the distribution of the base_time to
504 * the children and can be useful if the application manages the base_time
505 * itself, for example if you want to synchronize capture from multiple
506 * pipelines, and you can also ensure that the pipelines have the same clock.
511 gst_element_set_start_time (GstElement * element, GstClockTime time)
515 g_return_if_fail (GST_IS_ELEMENT (element));
517 GST_OBJECT_LOCK (element);
518 old = GST_ELEMENT_START_TIME (element);
519 GST_ELEMENT_START_TIME (element) = time;
520 GST_OBJECT_UNLOCK (element);
522 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
523 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
524 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
528 * gst_element_get_start_time:
529 * @element: a #GstElement.
531 * Returns the start time of the element. The start time is the
532 * running time of the clock when this element was last put to PAUSED.
534 * Usually the start_time is managed by a toplevel element such as
539 * Returns: the start time of the element.
542 gst_element_get_start_time (GstElement * element)
546 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
548 GST_OBJECT_LOCK (element);
549 result = GST_ELEMENT_START_TIME (element);
550 GST_OBJECT_UNLOCK (element);
557 * gst_element_set_index:
558 * @element: a #GstElement.
559 * @index: (transfer none): a #GstIndex.
561 * Set @index on the element. The refcount of the index
562 * will be increased, any previously set index is unreffed.
567 gst_element_set_index (GstElement * element, GstIndex * index)
569 GstElementClass *oclass;
571 g_return_if_fail (GST_IS_ELEMENT (element));
572 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
574 oclass = GST_ELEMENT_GET_CLASS (element);
576 if (oclass->set_index)
577 oclass->set_index (element, index);
581 * gst_element_get_index:
582 * @element: a #GstElement.
584 * Gets the index from the element.
586 * Returns: (transfer full) (nullable): a #GstIndex or %NULL when no
587 * index was set on the element. unref after usage.
592 gst_element_get_index (GstElement * element)
594 GstElementClass *oclass;
595 GstIndex *result = NULL;
597 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
599 oclass = GST_ELEMENT_GET_CLASS (element);
601 if (oclass->get_index)
602 result = oclass->get_index (element);
609 * gst_element_add_pad:
610 * @element: a #GstElement to add the pad to.
611 * @pad: (transfer full): the #GstPad to add to the element.
613 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
614 * see gst_object_set_parent() for refcounting information.
616 * Pads are not automatically activated so elements should perform the needed
617 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
618 * state. See gst_pad_set_active() for more information about activating pads.
620 * The pad and the element should be unlocked when calling this function.
622 * This function will emit the #GstElement::pad-added signal on the element.
624 * Returns: %TRUE if the pad could be added. This function can fail when
625 * a pad with the same name already existed or the pad already had another
631 gst_element_add_pad (GstElement * element, GstPad * pad)
636 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
637 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
639 /* locking pad to look at the name */
640 GST_OBJECT_LOCK (pad);
641 pad_name = g_strdup (GST_PAD_NAME (pad));
642 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
643 GST_STR_NULL (pad_name));
644 flushing = GST_PAD_IS_FLUSHING (pad);
645 GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_NEED_PARENT);
646 GST_OBJECT_UNLOCK (pad);
648 /* then check to see if there's already a pad by that name here */
649 GST_OBJECT_LOCK (element);
650 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
653 /* try to set the pad's parent */
654 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
655 GST_OBJECT_CAST (element))))
658 /* check for flushing pads */
659 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
660 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
661 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
662 "use gst_pad_set_active(pad,TRUE) before adding it.",
663 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
665 GST_OBJECT_LOCK (pad);
666 GST_PAD_UNSET_FLUSHING (pad);
667 GST_OBJECT_UNLOCK (pad);
672 /* add it to the list */
673 switch (gst_pad_get_direction (pad)) {
675 element->srcpads = g_list_append (element->srcpads, pad);
676 element->numsrcpads++;
679 element->sinkpads = g_list_append (element->sinkpads, pad);
680 element->numsinkpads++;
685 element->pads = g_list_append (element->pads, pad);
687 element->pads_cookie++;
688 GST_OBJECT_UNLOCK (element);
690 /* emit the PAD_ADDED signal */
691 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
698 g_critical ("Padname %s is not unique in element %s, not adding",
699 pad_name, GST_ELEMENT_NAME (element));
700 GST_OBJECT_UNLOCK (element);
707 ("Pad %s already has parent when trying to add to element %s",
708 pad_name, GST_ELEMENT_NAME (element));
709 GST_OBJECT_UNLOCK (element);
715 GST_OBJECT_LOCK (pad);
717 ("Trying to add pad %s to element %s, but it has no direction",
718 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
719 GST_OBJECT_UNLOCK (pad);
720 GST_OBJECT_UNLOCK (element);
726 * gst_element_remove_pad:
727 * @element: a #GstElement to remove pad from.
728 * @pad: (transfer full): the #GstPad to remove from the element.
730 * Removes @pad from @element. @pad will be destroyed if it has not been
731 * referenced elsewhere using gst_object_unparent().
733 * This function is used by plugin developers and should not be used
734 * by applications. Pads that were dynamically requested from elements
735 * with gst_element_request_pad() should be released with the
736 * gst_element_release_request_pad() function instead.
738 * Pads are not automatically deactivated so elements should perform the needed
739 * steps to deactivate the pad in case this pad is removed in the PAUSED or
740 * PLAYING state. See gst_pad_set_active() for more information about
743 * The pad and the element should be unlocked when calling this function.
745 * This function will emit the #GstElement::pad-removed signal on the element.
747 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
748 * pad does not belong to the provided element.
753 gst_element_remove_pad (GstElement * element, GstPad * pad)
757 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
758 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
760 /* locking pad to look at the name and parent */
761 GST_OBJECT_LOCK (pad);
762 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
763 GST_STR_NULL (GST_PAD_NAME (pad)));
765 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
767 GST_OBJECT_UNLOCK (pad);
770 if ((peer = gst_pad_get_peer (pad))) {
771 /* window for MT unsafeness, someone else could unlink here
772 * and then we call unlink with wrong pads. The unlink
773 * function would catch this and safely return failed. */
774 if (GST_PAD_IS_SRC (pad))
775 gst_pad_unlink (pad, peer);
777 gst_pad_unlink (peer, pad);
779 gst_object_unref (peer);
782 GST_OBJECT_LOCK (element);
783 /* remove it from the list */
784 switch (gst_pad_get_direction (pad)) {
786 element->srcpads = g_list_remove (element->srcpads, pad);
787 element->numsrcpads--;
790 element->sinkpads = g_list_remove (element->sinkpads, pad);
791 element->numsinkpads--;
794 g_critical ("Removing pad without direction???");
797 element->pads = g_list_remove (element->pads, pad);
798 GST_OBJECT_FLAG_UNSET (pad, GST_PAD_FLAG_NEED_PARENT);
800 element->pads_cookie++;
801 GST_OBJECT_UNLOCK (element);
803 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
804 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
806 gst_object_unparent (GST_OBJECT_CAST (pad));
813 /* locking order is element > pad */
814 GST_OBJECT_UNLOCK (pad);
816 GST_OBJECT_LOCK (element);
817 GST_OBJECT_LOCK (pad);
818 g_critical ("Padname %s:%s does not belong to element %s when removing",
819 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
820 GST_OBJECT_UNLOCK (pad);
821 GST_OBJECT_UNLOCK (element);
827 * gst_element_no_more_pads:
828 * @element: a #GstElement
830 * Use this function to signal that the element does not expect any more pads
831 * to show up in the current pipeline. This function should be called whenever
832 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
833 * pad templates use this in combination with autopluggers to figure out that
834 * the element is done initializing its pads.
836 * This function emits the #GstElement::no-more-pads signal.
841 gst_element_no_more_pads (GstElement * element)
843 g_return_if_fail (GST_IS_ELEMENT (element));
845 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
849 pad_compare_name (GstPad * pad1, const gchar * name)
853 GST_OBJECT_LOCK (pad1);
854 result = strcmp (GST_PAD_NAME (pad1), name);
855 GST_OBJECT_UNLOCK (pad1);
861 * gst_element_get_static_pad:
862 * @element: a #GstElement to find a static pad of.
863 * @name: the name of the static #GstPad to retrieve.
865 * Retrieves a pad from @element by name. This version only retrieves
866 * already-existing (i.e. 'static') pads.
868 * Returns: (transfer full) (nullable): the requested #GstPad if
869 * found, otherwise %NULL. unref after usage.
874 gst_element_get_static_pad (GstElement * element, const gchar * name)
877 GstPad *result = NULL;
879 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
880 g_return_val_if_fail (name != NULL, NULL);
882 GST_OBJECT_LOCK (element);
884 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
886 result = GST_PAD_CAST (find->data);
887 gst_object_ref (result);
890 if (result == NULL) {
891 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
892 name, GST_ELEMENT_NAME (element));
894 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
895 GST_ELEMENT_NAME (element), name);
897 GST_OBJECT_UNLOCK (element);
903 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
904 const gchar * name, const GstCaps * caps)
906 GstPad *newpad = NULL;
907 GstElementClass *oclass;
909 oclass = GST_ELEMENT_GET_CLASS (element);
911 #ifndef G_DISABLE_CHECKS
912 /* Some sanity checking here */
916 /* Is this the template name? */
917 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
918 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
920 const gchar *str, *data;
923 /* Otherwise check if it's a valid name for the name template */
924 str = strchr (templ->name_template, '%');
925 g_return_val_if_fail (str != NULL, NULL);
926 g_return_val_if_fail (strncmp (templ->name_template, name,
927 str - templ->name_template) == 0, NULL);
928 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
930 data = name + (str - templ->name_template);
932 /* Can either be %s or %d or %u, do sanity checking for %d */
933 if (*(str + 1) == 'd') {
937 tmp = g_ascii_strtoll (data, &endptr, 10);
938 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
939 && *endptr == '\0', NULL);
940 } else if (*(str + 1) == 'u') {
944 tmp = g_ascii_strtoull (data, &endptr, 10);
945 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
949 pad = gst_element_get_static_pad (element, name);
951 gst_object_unref (pad);
952 /* FIXME 2.0: Change this to g_return_val_if_fail() */
953 g_critical ("Element %s already has a pad named %s, the behaviour of "
954 " gst_element_get_request_pad() for existing pads is undefined!",
955 GST_ELEMENT_NAME (element), name);
960 if (oclass->request_new_pad)
961 newpad = (oclass->request_new_pad) (element, templ, name, caps);
964 gst_object_ref (newpad);
970 * gst_element_get_request_pad:
971 * @element: a #GstElement to find a request pad of.
972 * @name: the name of the request #GstPad to retrieve.
974 * Retrieves a pad from the element by name (e.g. "src_\%d"). This version only
975 * retrieves request pads. The pad should be released with
976 * gst_element_release_request_pad().
978 * This method is slower than manually getting the pad template and calling
979 * gst_element_request_pad() if the pads should have a specific name (e.g.
980 * @name is "src_1" instead of "src_%u").
982 * Returns: (transfer full) (nullable): requested #GstPad if found,
983 * otherwise %NULL. Release after usage.
986 gst_element_get_request_pad (GstElement * element, const gchar * name)
988 GstPadTemplate *templ = NULL;
990 const gchar *req_name = NULL;
991 gboolean templ_found = FALSE;
994 gchar *str, *endptr = NULL;
995 GstElementClass *class;
997 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
998 g_return_val_if_fail (name != NULL, NULL);
1000 class = GST_ELEMENT_GET_CLASS (element);
1002 /* if the name contains a %, we assume it's the complete template name. Get
1003 * the template and try to get a pad */
1004 if (strstr (name, "%")) {
1005 templ = gst_element_class_get_request_pad_template (class, name);
1010 /* there is no % in the name, try to find a matching template */
1011 list = class->padtemplates;
1012 while (!templ_found && list) {
1013 templ = (GstPadTemplate *) list->data;
1014 if (templ->presence == GST_PAD_REQUEST) {
1015 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1016 templ->name_template);
1017 /* see if we find an exact match */
1018 if (strcmp (name, templ->name_template) == 0) {
1023 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1024 and %d and %u, occurring at the end of the name_template, are the only
1026 else if ((str = strchr (templ->name_template, '%'))
1027 && strncmp (templ->name_template, name,
1028 str - templ->name_template) == 0
1029 && strlen (name) > str - templ->name_template) {
1030 data = name + (str - templ->name_template);
1031 if (*(str + 1) == 'd') {
1035 tmp = strtol (data, &endptr, 10);
1036 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1042 } else if (*(str + 1) == 'u') {
1046 tmp = strtoul (data, &endptr, 10);
1047 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1067 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1073 * gst_element_request_pad:
1074 * @element: a #GstElement to find a request pad of.
1075 * @templ: a #GstPadTemplate of which we want a pad of.
1076 * @name: (transfer none) (allow-none): the name of the request #GstPad
1077 * to retrieve. Can be %NULL.
1078 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1079 * request. Can be %NULL.
1081 * Retrieves a request pad from the element according to the provided template.
1082 * Pad templates can be looked up using
1083 * gst_element_factory_get_static_pad_templates().
1085 * The pad should be released with gst_element_release_request_pad().
1087 * Returns: (transfer full) (nullable): requested #GstPad if found,
1088 * otherwise %NULL. Release after usage.
1091 gst_element_request_pad (GstElement * element,
1092 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1094 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1095 g_return_val_if_fail (templ != NULL, NULL);
1096 g_return_val_if_fail (templ->presence == GST_PAD_REQUEST, NULL);
1098 return _gst_element_request_pad (element, templ, name, caps);
1101 static GstIterator *
1102 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1104 GstIterator *result;
1106 GST_OBJECT_LOCK (element);
1107 result = gst_iterator_new_list (GST_TYPE_PAD,
1108 GST_OBJECT_GET_LOCK (element),
1109 &element->pads_cookie, padlist, (GObject *) element, NULL);
1110 GST_OBJECT_UNLOCK (element);
1116 * gst_element_iterate_pads:
1117 * @element: a #GstElement to iterate pads of.
1119 * Retrieves an iterator of @element's pads. The iterator should
1120 * be freed after usage. Also more specialized iterators exists such as
1121 * gst_element_iterate_src_pads() or gst_element_iterate_sink_pads().
1123 * The order of pads returned by the iterator will be the order in which
1124 * the pads were added to the element.
1126 * Returns: (transfer full): the #GstIterator of #GstPad.
1131 gst_element_iterate_pads (GstElement * element)
1133 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1135 return gst_element_iterate_pad_list (element, &element->pads);
1139 * gst_element_iterate_src_pads:
1140 * @element: a #GstElement.
1142 * Retrieves an iterator of @element's source pads.
1144 * The order of pads returned by the iterator will be the order in which
1145 * the pads were added to the element.
1147 * Returns: (transfer full): the #GstIterator of #GstPad.
1152 gst_element_iterate_src_pads (GstElement * element)
1154 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1156 return gst_element_iterate_pad_list (element, &element->srcpads);
1160 * gst_element_iterate_sink_pads:
1161 * @element: a #GstElement.
1163 * Retrieves an iterator of @element's sink pads.
1165 * The order of pads returned by the iterator will be the order in which
1166 * the pads were added to the element.
1168 * Returns: (transfer full): the #GstIterator of #GstPad.
1173 gst_element_iterate_sink_pads (GstElement * element)
1175 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1177 return gst_element_iterate_pad_list (element, &element->sinkpads);
1181 * gst_element_class_add_pad_template:
1182 * @klass: the #GstElementClass to add the pad template to.
1183 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1185 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1186 * functions of classes. If a pad template with the same name as an already
1187 * existing one is added the old one is replaced by the new one.
1191 gst_element_class_add_pad_template (GstElementClass * klass,
1192 GstPadTemplate * templ)
1194 GList *template_list = klass->padtemplates;
1196 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1197 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1199 /* If we already have a pad template with the same name replace the
1201 while (template_list) {
1202 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1204 /* Found pad with the same name, replace and return */
1205 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1206 gst_object_unref (padtempl);
1207 template_list->data = templ;
1210 template_list = g_list_next (template_list);
1213 /* Take ownership of the floating ref */
1214 gst_object_ref_sink (templ);
1216 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1217 klass->numpadtemplates++;
1221 * gst_element_class_add_metadata:
1222 * @klass: class to set metadata for
1223 * @key: the key to set
1224 * @value: the value to set
1226 * Set @key with @value as metadata in @klass.
1229 gst_element_class_add_metadata (GstElementClass * klass,
1230 const gchar * key, const gchar * value)
1232 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1233 g_return_if_fail (key != NULL);
1234 g_return_if_fail (value != NULL);
1236 gst_structure_set ((GstStructure *) klass->metadata,
1237 key, G_TYPE_STRING, value, NULL);
1241 * gst_element_class_add_static_metadata:
1242 * @klass: class to set metadata for
1243 * @key: the key to set
1244 * @value: the value to set
1246 * Set @key with @value as metadata in @klass.
1248 * Same as gst_element_class_add_metadata(), but @value must be a static string
1249 * or an inlined string, as it will not be copied. (GStreamer plugins will
1250 * be made resident once loaded, so this function can be used even from
1251 * dynamically loaded plugins.)
1254 gst_element_class_add_static_metadata (GstElementClass * klass,
1255 const gchar * key, const gchar * value)
1257 GValue val = G_VALUE_INIT;
1259 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1260 g_return_if_fail (key != NULL);
1261 g_return_if_fail (value != NULL);
1263 g_value_init (&val, G_TYPE_STRING);
1264 g_value_set_static_string (&val, value);
1265 gst_structure_take_value ((GstStructure *) klass->metadata, key, &val);
1269 * gst_element_class_set_metadata:
1270 * @klass: class to set metadata for
1271 * @longname: The long English name of the element. E.g. "File Sink"
1272 * @classification: String describing the type of element, as an unordered list
1273 * separated with slashes ('/'). See draft-klass.txt of the design docs
1274 * for more details and common types. E.g: "Sink/File"
1275 * @description: Sentence describing the purpose of the element.
1276 * E.g: "Write stream to a file"
1277 * @author: Name and contact details of the author(s). Use \n to separate
1278 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1280 * Sets the detailed information for a #GstElementClass.
1281 * <note>This function is for use in _class_init functions only.</note>
1284 gst_element_class_set_metadata (GstElementClass * klass,
1285 const gchar * longname, const gchar * classification,
1286 const gchar * description, const gchar * author)
1288 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1289 g_return_if_fail (longname != NULL && *longname != '\0');
1290 g_return_if_fail (classification != NULL && *classification != '\0');
1291 g_return_if_fail (description != NULL && *description != '\0');
1292 g_return_if_fail (author != NULL && *author != '\0');
1294 gst_structure_id_set ((GstStructure *) klass->metadata,
1295 GST_QUARK (ELEMENT_METADATA_LONGNAME), G_TYPE_STRING, longname,
1296 GST_QUARK (ELEMENT_METADATA_KLASS), G_TYPE_STRING, classification,
1297 GST_QUARK (ELEMENT_METADATA_DESCRIPTION), G_TYPE_STRING, description,
1298 GST_QUARK (ELEMENT_METADATA_AUTHOR), G_TYPE_STRING, author, NULL);
1302 * gst_element_class_set_static_metadata:
1303 * @klass: class to set metadata for
1304 * @longname: The long English name of the element. E.g. "File Sink"
1305 * @classification: String describing the type of element, as an unordered list
1306 * separated with slashes ('/'). See draft-klass.txt of the design docs
1307 * for more details and common types. E.g: "Sink/File"
1308 * @description: Sentence describing the purpose of the element.
1309 * E.g: "Write stream to a file"
1310 * @author: Name and contact details of the author(s). Use \n to separate
1311 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1313 * Sets the detailed information for a #GstElementClass.
1314 * <note>This function is for use in _class_init functions only.</note>
1316 * Same as gst_element_class_set_metadata(), but @longname, @classification,
1317 * @description, and @author must be static strings or inlined strings, as
1318 * they will not be copied. (GStreamer plugins will be made resident once
1319 * loaded, so this function can be used even from dynamically loaded plugins.)
1322 gst_element_class_set_static_metadata (GstElementClass * klass,
1323 const gchar * longname, const gchar * classification,
1324 const gchar * description, const gchar * author)
1326 GstStructure *s = (GstStructure *) klass->metadata;
1327 GValue val = G_VALUE_INIT;
1329 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1330 g_return_if_fail (longname != NULL && *longname != '\0');
1331 g_return_if_fail (classification != NULL && *classification != '\0');
1332 g_return_if_fail (description != NULL && *description != '\0');
1333 g_return_if_fail (author != NULL && *author != '\0');
1335 g_value_init (&val, G_TYPE_STRING);
1337 g_value_set_static_string (&val, longname);
1338 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_LONGNAME), &val);
1340 g_value_set_static_string (&val, classification);
1341 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_KLASS), &val);
1343 g_value_set_static_string (&val, description);
1344 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_DESCRIPTION),
1347 g_value_set_static_string (&val, author);
1348 gst_structure_id_take_value (s, GST_QUARK (ELEMENT_METADATA_AUTHOR), &val);
1352 * gst_element_class_get_metadata:
1353 * @klass: class to get metadata for
1354 * @key: the key to get
1356 * Get metadata with @key in @klass.
1358 * Returns: the metadata for @key.
1361 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1363 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1364 g_return_val_if_fail (key != NULL, NULL);
1366 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1370 * gst_element_class_get_pad_template_list:
1371 * @element_class: a #GstElementClass to get pad templates of.
1373 * Retrieves a list of the pad templates associated with @element_class. The
1374 * list must not be modified by the calling code.
1375 * <note>If you use this function in the #GInstanceInitFunc of an object class
1376 * that has subclasses, make sure to pass the g_class parameter of the
1377 * #GInstanceInitFunc here.</note>
1379 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1383 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1385 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1387 return element_class->padtemplates;
1391 * gst_element_class_get_pad_template:
1392 * @element_class: a #GstElementClass to get the pad template of.
1393 * @name: the name of the #GstPadTemplate to get.
1395 * Retrieves a padtemplate from @element_class with the given name.
1396 * <note>If you use this function in the #GInstanceInitFunc of an object class
1397 * that has subclasses, make sure to pass the g_class parameter of the
1398 * #GInstanceInitFunc here.</note>
1400 * Returns: (transfer none) (nullable): the #GstPadTemplate with the
1401 * given name, or %NULL if none was found. No unreferencing is
1405 gst_element_class_get_pad_template (GstElementClass *
1406 element_class, const gchar * name)
1410 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1411 g_return_val_if_fail (name != NULL, NULL);
1413 padlist = element_class->padtemplates;
1416 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1418 if (strcmp (padtempl->name_template, name) == 0)
1421 padlist = g_list_next (padlist);
1427 static GstPadTemplate *
1428 gst_element_class_get_request_pad_template (GstElementClass *
1429 element_class, const gchar * name)
1431 GstPadTemplate *tmpl;
1433 tmpl = gst_element_class_get_pad_template (element_class, name);
1434 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1440 /* get a random pad on element of the given direction.
1441 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1444 gst_element_get_random_pad (GstElement * element,
1445 gboolean need_linked, GstPadDirection dir)
1447 GstPad *result = NULL;
1450 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1454 GST_OBJECT_LOCK (element);
1455 pads = element->srcpads;
1458 GST_OBJECT_LOCK (element);
1459 pads = element->sinkpads;
1462 goto wrong_direction;
1464 for (; pads; pads = g_list_next (pads)) {
1465 GstPad *pad = GST_PAD_CAST (pads->data);
1467 GST_OBJECT_LOCK (pad);
1468 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1469 GST_DEBUG_PAD_NAME (pad));
1471 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1472 /* if we require a linked pad, and it is not linked, continue the
1474 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1475 GST_DEBUG_PAD_NAME (pad));
1476 GST_OBJECT_UNLOCK (pad);
1479 /* found a pad, stop search */
1480 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1481 GST_DEBUG_PAD_NAME (pad));
1482 GST_OBJECT_UNLOCK (pad);
1488 gst_object_ref (result);
1490 GST_OBJECT_UNLOCK (element);
1494 /* ERROR handling */
1497 g_warning ("unknown pad direction %d", dir);
1503 gst_element_default_send_event (GstElement * element, GstEvent * event)
1505 gboolean result = FALSE;
1508 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1509 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1510 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1513 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1514 "pushing %s event to random %s pad %s:%s",
1515 GST_EVENT_TYPE_NAME (event),
1516 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1517 GST_DEBUG_PAD_NAME (pad));
1519 result = gst_pad_push_event (pad, event);
1520 gst_object_unref (pad);
1522 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1523 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1524 gst_event_unref (event);
1530 * gst_element_send_event:
1531 * @element: a #GstElement to send the event to.
1532 * @event: (transfer full): the #GstEvent to send to the element.
1534 * Sends an event to an element. If the element doesn't implement an
1535 * event handler, the event will be pushed on a random linked sink pad for
1536 * upstream events or a random linked source pad for downstream events.
1538 * This function takes ownership of the provided event so you should
1539 * gst_event_ref() it if you want to reuse the event after this call.
1543 * Returns: %TRUE if the event was handled. Events that trigger a preroll (such
1544 * as flushing seeks and steps) will emit %GST_MESSAGE_ASYNC_DONE.
1547 gst_element_send_event (GstElement * element, GstEvent * event)
1549 GstElementClass *oclass;
1550 gboolean result = FALSE;
1552 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1553 g_return_val_if_fail (event != NULL, FALSE);
1555 oclass = GST_ELEMENT_GET_CLASS (element);
1557 GST_STATE_LOCK (element);
1558 if (oclass->send_event) {
1559 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1560 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1561 result = oclass->send_event (element, event);
1563 GST_STATE_UNLOCK (element);
1570 * @element: a #GstElement to send the event to.
1571 * @rate: The new playback rate
1572 * @format: The format of the seek values
1573 * @flags: The optional seek flags.
1574 * @start_type: The type and flags for the new start position
1575 * @start: The value of the new start position
1576 * @stop_type: The type and flags for the new stop position
1577 * @stop: The value of the new stop position
1579 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1580 * the parameters. The seek event is sent to the element using
1581 * gst_element_send_event().
1585 * Returns: %TRUE if the event was handled. Flushing seeks will trigger a
1586 * preroll, which will emit %GST_MESSAGE_ASYNC_DONE.
1589 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1590 GstSeekFlags flags, GstSeekType start_type, gint64 start,
1591 GstSeekType stop_type, gint64 stop)
1596 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1599 gst_event_new_seek (rate, format, flags, start_type, start, stop_type,
1601 result = gst_element_send_event (element, event);
1607 gst_element_default_query (GstElement * element, GstQuery * query)
1609 gboolean result = FALSE;
1612 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1614 result = gst_pad_query (pad, query);
1616 gst_object_unref (pad);
1618 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1620 GstPad *peer = gst_pad_get_peer (pad);
1623 result = gst_pad_query (peer, query);
1625 gst_object_unref (peer);
1627 gst_object_unref (pad);
1634 * gst_element_query:
1635 * @element: a #GstElement to perform the query on.
1636 * @query: (transfer none): the #GstQuery.
1638 * Performs a query on the given element.
1640 * For elements that don't implement a query handler, this function
1641 * forwards the query to a random srcpad or to the peer of a
1642 * random linked sinkpad of this element.
1644 * Please note that some queries might need a running pipeline to work.
1646 * Returns: %TRUE if the query could be performed.
1651 gst_element_query (GstElement * element, GstQuery * query)
1653 GstElementClass *klass;
1655 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1656 g_return_val_if_fail (query != NULL, FALSE);
1658 klass = GST_ELEMENT_GET_CLASS (element);
1660 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1661 GST_ELEMENT_NAME (element));
1662 return klass->query (element, query);
1669 gst_element_post_message_default (GstElement * element, GstMessage * message)
1672 gboolean result = FALSE;
1674 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1675 g_return_val_if_fail (message != NULL, FALSE);
1677 GST_OBJECT_LOCK (element);
1680 if (G_UNLIKELY (bus == NULL))
1683 gst_object_ref (bus);
1684 GST_OBJECT_UNLOCK (element);
1686 /* we release the element lock when posting the message so that any
1687 * (synchronous) message handlers can operate on the element */
1688 result = gst_bus_post (bus, message);
1689 gst_object_unref (bus);
1696 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1697 "not posting message %p: no bus", message);
1698 GST_OBJECT_UNLOCK (element);
1699 gst_message_unref (message);
1705 * gst_element_post_message:
1706 * @element: a #GstElement posting the message
1707 * @message: (transfer full): a #GstMessage to post
1709 * Post a message on the element's #GstBus. This function takes ownership of the
1710 * message; if you want to access the message after this call, you should add an
1711 * additional reference before calling.
1713 * Returns: %TRUE if the message was successfully posted. The function returns
1714 * %FALSE if the element did not have a bus.
1719 gst_element_post_message (GstElement * element, GstMessage * message)
1721 GstElementClass *klass;
1723 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1724 g_return_val_if_fail (message != NULL, FALSE);
1726 klass = GST_ELEMENT_GET_CLASS (element);
1727 if (klass->post_message)
1728 return klass->post_message (element, message);
1734 * _gst_element_error_printf:
1735 * @format: (allow-none): the printf-like format to use, or %NULL
1737 * This function is only used internally by the gst_element_error() macro.
1739 * Returns: (transfer full) (nullable): a newly allocated string, or
1740 * %NULL if the format was %NULL or ""
1745 _gst_element_error_printf (const gchar * format, ...)
1756 va_start (args, format);
1758 len = __gst_vasprintf (&buffer, format, args);
1769 * gst_element_message_full:
1770 * @element: a #GstElement to send message from
1771 * @type: the #GstMessageType
1772 * @domain: the GStreamer GError domain this message belongs to
1773 * @code: the GError code belonging to the domain
1774 * @text: (allow-none) (transfer full): an allocated text string to be used
1775 * as a replacement for the default message connected to code,
1777 * @debug: (allow-none) (transfer full): an allocated debug message to be
1778 * used as a replacement for the default debugging information,
1780 * @file: the source code file where the error was generated
1781 * @function: the source code function where the error was generated
1782 * @line: the source code line where the error was generated
1784 * Post an error, warning or info message on the bus from inside an element.
1786 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1787 * #GST_MESSAGE_INFO.
1791 void gst_element_message_full
1792 (GstElement * element, GstMessageType type,
1793 GQuark domain, gint code, gchar * text,
1794 gchar * debug, const gchar * file, const gchar * function, gint line)
1796 GError *gerror = NULL;
1800 gboolean has_debug = TRUE;
1801 GstMessage *message = NULL;
1804 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1805 g_return_if_fail (GST_IS_ELEMENT (element));
1806 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1807 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1809 /* check if we send the given text or the default error text */
1810 if ((text == NULL) || (text[0] == 0)) {
1811 /* text could have come from g_strdup_printf (""); */
1813 sent_text = gst_error_get_message (domain, code);
1817 /* construct a sent_debug with extra information from source */
1818 if ((debug == NULL) || (debug[0] == 0)) {
1819 /* debug could have come from g_strdup_printf (""); */
1823 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1825 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1826 file, line, function, name, debug);
1828 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1829 file, line, function, name);
1833 /* create gerror and post message */
1834 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1836 gerror = g_error_new_literal (domain, code, sent_text);
1839 case GST_MESSAGE_ERROR:
1841 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1843 case GST_MESSAGE_WARNING:
1844 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1847 case GST_MESSAGE_INFO:
1848 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1852 g_assert_not_reached ();
1855 gst_element_post_message (element, message);
1857 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1858 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1861 g_error_free (gerror);
1862 g_free (sent_debug);
1867 * gst_element_is_locked_state:
1868 * @element: a #GstElement.
1870 * Checks if the state of an element is locked.
1871 * If the state of an element is locked, state changes of the parent don't
1872 * affect the element.
1873 * This way you can leave currently unused elements inside bins. Just lock their
1874 * state before changing the state from #GST_STATE_NULL.
1878 * Returns: %TRUE, if the element's state is locked.
1881 gst_element_is_locked_state (GstElement * element)
1885 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1887 GST_OBJECT_LOCK (element);
1888 result = GST_ELEMENT_IS_LOCKED_STATE (element);
1889 GST_OBJECT_UNLOCK (element);
1895 * gst_element_set_locked_state:
1896 * @element: a #GstElement
1897 * @locked_state: %TRUE to lock the element's state
1899 * Locks the state of an element, so state changes of the parent don't affect
1900 * this element anymore.
1904 * Returns: %TRUE if the state was changed, %FALSE if bad parameters were given
1905 * or the elements state-locking needed no change.
1908 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1912 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1914 GST_OBJECT_LOCK (element);
1915 old = GST_ELEMENT_IS_LOCKED_STATE (element);
1917 if (G_UNLIKELY (old == locked_state))
1921 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1922 GST_ELEMENT_NAME (element));
1923 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1925 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1926 GST_ELEMENT_NAME (element));
1927 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1929 GST_OBJECT_UNLOCK (element);
1935 GST_CAT_DEBUG (GST_CAT_STATES,
1936 "elements %s was already in locked state %d",
1937 GST_ELEMENT_NAME (element), old);
1938 GST_OBJECT_UNLOCK (element);
1945 * gst_element_sync_state_with_parent:
1946 * @element: a #GstElement.
1948 * Tries to change the state of the element to the same as its parent.
1949 * If this function returns %FALSE, the state of element is undefined.
1951 * Returns: %TRUE, if the element's state could be synced to the parent's state.
1956 gst_element_sync_state_with_parent (GstElement * element)
1960 GstStateChangeReturn ret;
1962 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1964 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1965 GstState parent_current, parent_pending;
1967 GST_OBJECT_LOCK (parent);
1968 parent_current = GST_STATE (parent);
1969 parent_pending = GST_STATE_PENDING (parent);
1970 GST_OBJECT_UNLOCK (parent);
1972 /* set to pending if there is one, else we set it to the current state of
1974 if (parent_pending != GST_STATE_VOID_PENDING)
1975 target = parent_pending;
1977 target = parent_current;
1979 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1980 "syncing state (%s) to parent %s %s (%s, %s)",
1981 gst_element_state_get_name (GST_STATE (element)),
1982 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1983 gst_element_state_get_name (parent_current),
1984 gst_element_state_get_name (parent_pending));
1986 ret = gst_element_set_state (element, target);
1987 if (ret == GST_STATE_CHANGE_FAILURE)
1990 gst_object_unref (parent);
1994 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
2001 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2002 "syncing state failed (%s)",
2003 gst_element_state_change_return_get_name (ret));
2004 gst_object_unref (parent);
2010 static GstStateChangeReturn
2011 gst_element_get_state_func (GstElement * element,
2012 GstState * state, GstState * pending, GstClockTime timeout)
2014 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2015 GstState old_pending;
2017 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2018 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2020 GST_OBJECT_LOCK (element);
2021 ret = GST_STATE_RETURN (element);
2022 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2023 gst_element_state_change_return_get_name (ret));
2025 /* we got an error, report immediately */
2026 if (ret == GST_STATE_CHANGE_FAILURE)
2029 /* we got no_preroll, report immediately */
2030 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2033 /* no need to wait async if we are not async */
2034 if (ret != GST_STATE_CHANGE_ASYNC)
2037 old_pending = GST_STATE_PENDING (element);
2038 if (old_pending != GST_STATE_VOID_PENDING) {
2042 /* get cookie to detect state changes during waiting */
2043 cookie = element->state_cookie;
2045 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2046 "waiting for element to commit state");
2048 /* we have a pending state change, wait for it to complete */
2049 if (timeout != GST_CLOCK_TIME_NONE) {
2051 /* make timeout absolute */
2052 end_time = g_get_monotonic_time () + (timeout / 1000);
2053 signaled = GST_STATE_WAIT_UNTIL (element, end_time);
2055 GST_STATE_WAIT (element);
2060 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2061 /* timeout triggered */
2062 ret = GST_STATE_CHANGE_ASYNC;
2064 if (cookie != element->state_cookie)
2067 /* could be success or failure */
2068 if (old_pending == GST_STATE (element)) {
2069 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2070 ret = GST_STATE_CHANGE_SUCCESS;
2072 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2073 ret = GST_STATE_CHANGE_FAILURE;
2076 /* if nothing is pending anymore we can return SUCCESS */
2077 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2078 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2079 ret = GST_STATE_CHANGE_SUCCESS;
2085 *state = GST_STATE (element);
2087 *pending = GST_STATE_PENDING (element);
2089 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2090 "state current: %s, pending: %s, result: %s",
2091 gst_element_state_get_name (GST_STATE (element)),
2092 gst_element_state_get_name (GST_STATE_PENDING (element)),
2093 gst_element_state_change_return_get_name (ret));
2094 GST_OBJECT_UNLOCK (element);
2101 *state = GST_STATE_VOID_PENDING;
2103 *pending = GST_STATE_VOID_PENDING;
2105 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2107 GST_OBJECT_UNLOCK (element);
2109 return GST_STATE_CHANGE_FAILURE;
2114 * gst_element_get_state:
2115 * @element: a #GstElement to get the state of.
2116 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2118 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2119 * state. Can be %NULL.
2120 * @timeout: a #GstClockTime to specify the timeout for an async
2121 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2123 * Gets the state of the element.
2125 * For elements that performed an ASYNC state change, as reported by
2126 * gst_element_set_state(), this function will block up to the
2127 * specified timeout value for the state change to complete.
2128 * If the element completes the state change or goes into
2129 * an error, this function returns immediately with a return value of
2130 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2132 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2133 * returns the current and pending state immediately.
2135 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2136 * successfully changed its state but is not able to provide data yet.
2137 * This mostly happens for live sources that only produce data in
2138 * %GST_STATE_PLAYING. While the state change return is equivalent to
2139 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2140 * some sink elements might not be able to complete their state change because
2141 * an element is not producing data to complete the preroll. When setting the
2142 * element to playing, the preroll will complete and playback will start.
2144 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2145 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2146 * element is still performing a state change or
2147 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2151 GstStateChangeReturn
2152 gst_element_get_state (GstElement * element,
2153 GstState * state, GstState * pending, GstClockTime timeout)
2155 GstElementClass *oclass;
2156 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2158 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2160 oclass = GST_ELEMENT_GET_CLASS (element);
2162 if (oclass->get_state)
2163 result = (oclass->get_state) (element, state, pending, timeout);
2169 * gst_element_abort_state:
2170 * @element: a #GstElement to abort the state of.
2172 * Abort the state change of the element. This function is used
2173 * by elements that do asynchronous state changes and find out
2174 * something is wrong.
2176 * This function should be called with the STATE_LOCK held.
2181 gst_element_abort_state (GstElement * element)
2185 #ifndef GST_DISABLE_GST_DEBUG
2189 g_return_if_fail (GST_IS_ELEMENT (element));
2191 GST_OBJECT_LOCK (element);
2192 pending = GST_STATE_PENDING (element);
2194 if (pending == GST_STATE_VOID_PENDING ||
2195 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2196 goto nothing_aborted;
2198 #ifndef GST_DISABLE_GST_DEBUG
2199 old_state = GST_STATE (element);
2201 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2202 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2203 gst_element_state_get_name (pending));
2207 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2209 GST_STATE_BROADCAST (element);
2210 GST_OBJECT_UNLOCK (element);
2216 GST_OBJECT_UNLOCK (element);
2221 /* Not static because GstBin has manual state handling too */
2223 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2224 GstState newstate, GstState pending)
2226 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2227 GstMessage *message;
2229 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2230 "notifying about state-changed %s to %s (%s pending)",
2231 gst_element_state_get_name (oldstate),
2232 gst_element_state_get_name (newstate),
2233 gst_element_state_get_name (pending));
2235 if (klass->state_changed)
2236 klass->state_changed (element, oldstate, newstate, pending);
2238 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2239 oldstate, newstate, pending);
2240 gst_element_post_message (element, message);
2244 * gst_element_continue_state:
2245 * @element: a #GstElement to continue the state change of.
2246 * @ret: The previous state return value
2248 * Commit the state change of the element and proceed to the next
2249 * pending state if any. This function is used
2250 * by elements that do asynchronous state changes.
2251 * The core will normally call this method automatically when an
2252 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2254 * If after calling this method the element still has not reached
2255 * the pending state, the next state change is performed.
2257 * This method is used internally and should normally not be called by plugins
2260 * Returns: The result of the commit state change.
2264 GstStateChangeReturn
2265 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2267 GstStateChangeReturn old_ret;
2268 GstState old_state, old_next;
2269 GstState current, next, pending;
2270 GstStateChange transition;
2272 GST_OBJECT_LOCK (element);
2273 old_ret = GST_STATE_RETURN (element);
2274 GST_STATE_RETURN (element) = ret;
2275 pending = GST_STATE_PENDING (element);
2277 /* check if there is something to commit */
2278 if (pending == GST_STATE_VOID_PENDING)
2279 goto nothing_pending;
2281 old_state = GST_STATE (element);
2282 /* this is the state we should go to next */
2283 old_next = GST_STATE_NEXT (element);
2284 /* update current state */
2285 current = GST_STATE (element) = old_next;
2287 /* see if we reached the final state */
2288 if (pending == current)
2291 next = GST_STATE_GET_NEXT (current, pending);
2292 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2294 GST_STATE_NEXT (element) = next;
2296 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2297 GST_OBJECT_UNLOCK (element);
2299 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2300 "committing state from %s to %s, pending %s, next %s",
2301 gst_element_state_get_name (old_state),
2302 gst_element_state_get_name (old_next),
2303 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2305 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2307 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2308 "continue state change %s to %s, final %s",
2309 gst_element_state_get_name (current),
2310 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2312 ret = gst_element_change_state (element, transition);
2318 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2319 GST_OBJECT_UNLOCK (element);
2324 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2325 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2327 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2328 "completed state change to %s", gst_element_state_get_name (pending));
2329 GST_OBJECT_UNLOCK (element);
2331 /* don't post silly messages with the same state. This can happen
2332 * when an element state is changed to what it already was. For bins
2333 * this can be the result of a lost state, which we check with the
2334 * previous return value.
2335 * We do signal the cond though as a _get_state() might be blocking
2337 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2338 _priv_gst_element_state_changed (element, old_state, old_next,
2339 GST_STATE_VOID_PENDING);
2341 GST_STATE_BROADCAST (element);
2348 * gst_element_lost_state:
2349 * @element: a #GstElement the state is lost of
2351 * Brings the element to the lost state. The current state of the
2352 * element is copied to the pending state so that any call to
2353 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2355 * An ASYNC_START message is posted. If the element was PLAYING, it will
2356 * go to PAUSED. The element will be restored to its PLAYING state by
2357 * the parent pipeline when it prerolls again.
2359 * This is mostly used for elements that lost their preroll buffer
2360 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2361 * they will go to their pending state again when a new preroll buffer is
2362 * queued. This function can only be called when the element is currently
2363 * not in error or an async state change.
2365 * This function is used internally and should normally not be called from
2366 * plugins or applications.
2369 gst_element_lost_state (GstElement * element)
2371 GstState old_state, new_state;
2372 GstMessage *message;
2374 g_return_if_fail (GST_IS_ELEMENT (element));
2376 GST_OBJECT_LOCK (element);
2377 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2380 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2381 goto only_async_start;
2383 old_state = GST_STATE (element);
2385 /* when we were PLAYING, the new state is PAUSED. We will also not
2386 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2387 * when we preroll. */
2388 if (old_state > GST_STATE_PAUSED)
2389 new_state = GST_STATE_PAUSED;
2391 new_state = old_state;
2393 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2394 "lost state of %s to %s", gst_element_state_get_name (old_state),
2395 gst_element_state_get_name (new_state));
2397 GST_STATE (element) = new_state;
2398 GST_STATE_NEXT (element) = new_state;
2399 GST_STATE_PENDING (element) = new_state;
2400 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2401 GST_OBJECT_UNLOCK (element);
2403 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2405 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2406 gst_element_post_message (element, message);
2412 GST_OBJECT_UNLOCK (element);
2417 GST_OBJECT_UNLOCK (element);
2419 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2420 gst_element_post_message (element, message);
2426 * gst_element_set_state:
2427 * @element: a #GstElement to change state of.
2428 * @state: the element's new #GstState.
2430 * Sets the state of the element. This function will try to set the
2431 * requested state by going through all the intermediary states and calling
2432 * the class's state change function for each.
2434 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2435 * element will perform the remainder of the state change asynchronously in
2437 * An application can use gst_element_get_state() to wait for the completion
2438 * of the state change or it can wait for a %GST_MESSAGE_ASYNC_DONE or
2439 * %GST_MESSAGE_STATE_CHANGED on the bus.
2441 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2442 * #GST_STATE_CHANGE_ASYNC.
2444 * Returns: Result of the state change using #GstStateChangeReturn.
2448 GstStateChangeReturn
2449 gst_element_set_state (GstElement * element, GstState state)
2451 GstElementClass *oclass;
2452 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2454 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2456 oclass = GST_ELEMENT_GET_CLASS (element);
2458 if (oclass->set_state)
2459 result = (oclass->set_state) (element, state);
2465 * default set state function, calculates the next state based
2466 * on current state and calls the change_state function
2468 static GstStateChangeReturn
2469 gst_element_set_state_func (GstElement * element, GstState state)
2471 GstState current, next, old_pending;
2472 GstStateChangeReturn ret;
2473 GstStateChange transition;
2474 GstStateChangeReturn old_ret;
2476 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2478 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2479 gst_element_state_get_name (state));
2481 /* state lock is taken to protect the set_state() and get_state()
2482 * procedures, it does not lock any variables. */
2483 GST_STATE_LOCK (element);
2485 /* now calculate how to get to the new state */
2486 GST_OBJECT_LOCK (element);
2487 old_ret = GST_STATE_RETURN (element);
2488 /* previous state change returned an error, remove all pending
2489 * and next states */
2490 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2491 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2492 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2493 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2496 current = GST_STATE (element);
2497 next = GST_STATE_NEXT (element);
2498 old_pending = GST_STATE_PENDING (element);
2500 /* this is the (new) state we should go to. TARGET is the last state we set on
2502 if (state != GST_STATE_TARGET (element)) {
2503 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2504 "setting target state to %s", gst_element_state_get_name (state));
2505 GST_STATE_TARGET (element) = state;
2506 /* increment state cookie so that we can track each state change. We only do
2507 * this if this is actually a new state change. */
2508 element->state_cookie++;
2510 GST_STATE_PENDING (element) = state;
2512 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2513 "current %s, old_pending %s, next %s, old return %s",
2514 gst_element_state_get_name (current),
2515 gst_element_state_get_name (old_pending),
2516 gst_element_state_get_name (next),
2517 gst_element_state_change_return_get_name (old_ret));
2519 /* if the element was busy doing a state change, we just update the
2520 * target state, it'll get to it async then. */
2521 if (old_pending != GST_STATE_VOID_PENDING) {
2522 /* upwards state change will happen ASYNC */
2523 if (old_pending <= state)
2525 /* element is going to this state already */
2526 else if (next == state)
2528 /* element was performing an ASYNC upward state change and
2529 * we request to go downward again. Start from the next pending
2531 else if (next > state
2532 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2536 next = GST_STATE_GET_NEXT (current, state);
2537 /* now we store the next state */
2538 GST_STATE_NEXT (element) = next;
2539 /* mark busy, we need to check that there is actually a state change
2540 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2541 * the default element change_state function has no way to know what the
2542 * old value was... could consider this a FIXME...*/
2543 if (current != next)
2544 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2546 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2548 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2549 "%s: setting state from %s to %s",
2550 (next != state ? "intermediate" : "final"),
2551 gst_element_state_get_name (current), gst_element_state_get_name (next));
2553 /* now signal any waiters, they will error since the cookie was incremented */
2554 GST_STATE_BROADCAST (element);
2556 GST_OBJECT_UNLOCK (element);
2558 ret = gst_element_change_state (element, transition);
2560 GST_STATE_UNLOCK (element);
2562 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2563 gst_element_state_change_return_get_name (ret));
2569 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2570 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2571 "element was busy with async state change");
2572 GST_OBJECT_UNLOCK (element);
2574 GST_STATE_UNLOCK (element);
2576 return GST_STATE_CHANGE_ASYNC;
2581 * gst_element_change_state:
2582 * @element: a #GstElement
2583 * @transition: the requested transition
2585 * Perform @transition on @element.
2587 * This function must be called with STATE_LOCK held and is mainly used
2590 * Returns: the #GstStateChangeReturn of the state transition.
2592 GstStateChangeReturn
2593 gst_element_change_state (GstElement * element, GstStateChange transition)
2595 GstElementClass *oclass;
2596 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2598 oclass = GST_ELEMENT_GET_CLASS (element);
2600 /* call the state change function so it can set the state */
2601 if (oclass->change_state)
2602 ret = (oclass->change_state) (element, transition);
2604 ret = GST_STATE_CHANGE_FAILURE;
2607 case GST_STATE_CHANGE_FAILURE:
2608 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2609 "have FAILURE change_state return");
2610 /* state change failure */
2611 gst_element_abort_state (element);
2613 case GST_STATE_CHANGE_ASYNC:
2617 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2618 "element will change state ASYNC");
2620 target = GST_STATE_TARGET (element);
2622 if (target > GST_STATE_READY)
2625 /* else we just continue the state change downwards */
2626 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2627 "forcing commit state %s <= %s",
2628 gst_element_state_get_name (target),
2629 gst_element_state_get_name (GST_STATE_READY));
2631 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2634 case GST_STATE_CHANGE_SUCCESS:
2635 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2636 "element changed state SUCCESS");
2637 /* we can commit the state now which will proceeed to
2639 ret = gst_element_continue_state (element, ret);
2641 case GST_STATE_CHANGE_NO_PREROLL:
2642 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2643 "element changed state NO_PREROLL");
2644 /* we can commit the state now which will proceeed to
2646 ret = gst_element_continue_state (element, ret);
2649 goto invalid_return;
2652 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2657 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2665 GST_OBJECT_LOCK (element);
2666 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2667 g_critical ("%s: unknown return value %d from a state change function",
2668 GST_ELEMENT_NAME (element), ret);
2670 /* we are in error now */
2671 ret = GST_STATE_CHANGE_FAILURE;
2672 GST_STATE_RETURN (element) = ret;
2673 GST_OBJECT_UNLOCK (element);
2679 /* gst_iterator_fold functions for pads_activate
2680 * Stop the iterator if activating one pad failed. */
2682 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2684 GstPad *pad = g_value_get_object (vpad);
2685 gboolean cont = TRUE;
2687 if (!(cont = gst_pad_set_active (pad, *active)))
2688 g_value_set_boolean (ret, FALSE);
2693 /* returns false on error or early cutout of the fold, true if all
2694 * pads in @iter were (de)activated successfully. */
2696 iterator_activate_fold_with_resync (GstIterator * iter,
2697 GstIteratorFoldFunction func, gpointer user_data)
2699 GstIteratorResult ires;
2702 /* no need to unset this later, it's just a boolean */
2703 g_value_init (&ret, G_TYPE_BOOLEAN);
2704 g_value_set_boolean (&ret, TRUE);
2707 ires = gst_iterator_fold (iter, func, &ret, user_data);
2709 case GST_ITERATOR_RESYNC:
2710 /* need to reset the result again */
2711 g_value_set_boolean (&ret, TRUE);
2712 gst_iterator_resync (iter);
2714 case GST_ITERATOR_DONE:
2715 /* all pads iterated, return collected value */
2718 /* iterator returned _ERROR or premature end with _OK,
2719 * mark an error and exit */
2720 g_value_set_boolean (&ret, FALSE);
2725 /* return collected value */
2726 return g_value_get_boolean (&ret);
2729 /* is called with STATE_LOCK
2731 * Pads are activated from source pads to sinkpads.
2734 gst_element_pads_activate (GstElement * element, gboolean active)
2739 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2740 "%s pads", active ? "activate" : "deactivate");
2742 iter = gst_element_iterate_src_pads (element);
2744 iterator_activate_fold_with_resync (iter,
2745 (GstIteratorFoldFunction) activate_pads, &active);
2746 gst_iterator_free (iter);
2747 if (G_UNLIKELY (!res))
2750 iter = gst_element_iterate_sink_pads (element);
2752 iterator_activate_fold_with_resync (iter,
2753 (GstIteratorFoldFunction) activate_pads, &active);
2754 gst_iterator_free (iter);
2755 if (G_UNLIKELY (!res))
2758 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2759 "pad %sactivation successful", active ? "" : "de");
2766 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2767 "pad %sactivation failed", active ? "" : "de");
2772 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2773 "sink pads_activate failed");
2778 /* is called with STATE_LOCK */
2779 static GstStateChangeReturn
2780 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2782 GstState state, next;
2783 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2785 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2787 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2788 next = GST_STATE_TRANSITION_NEXT (transition);
2790 /* if the element already is in the given state, we just return success */
2791 if (next == GST_STATE_VOID_PENDING || state == next)
2794 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2795 "default handler tries setting state from %s to %s (%04x)",
2796 gst_element_state_get_name (state),
2797 gst_element_state_get_name (next), transition);
2799 switch (transition) {
2800 case GST_STATE_CHANGE_NULL_TO_READY:
2802 case GST_STATE_CHANGE_READY_TO_PAUSED:
2803 if (!gst_element_pads_activate (element, TRUE)) {
2804 result = GST_STATE_CHANGE_FAILURE;
2807 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2809 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2811 case GST_STATE_CHANGE_PAUSED_TO_READY:
2812 case GST_STATE_CHANGE_READY_TO_NULL:
2813 /* deactivate pads in both cases, since they are activated on
2814 ready->paused but the element might not have made it to paused */
2815 if (!gst_element_pads_activate (element, FALSE)) {
2816 result = GST_STATE_CHANGE_FAILURE;
2820 /* this will catch real but unhandled state changes;
2821 * can only be caused by:
2822 * - a new state was added
2823 * - somehow the element was asked to jump across an intermediate state
2825 g_warning ("Unhandled state change from %s to %s",
2826 gst_element_state_get_name (state),
2827 gst_element_state_get_name (next));
2834 GST_OBJECT_LOCK (element);
2835 result = GST_STATE_RETURN (element);
2836 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2837 "element is already in the %s state",
2838 gst_element_state_get_name (state));
2839 GST_OBJECT_UNLOCK (element);
2846 * gst_element_get_factory:
2847 * @element: a #GstElement to request the element factory of.
2849 * Retrieves the factory that was used to create this element.
2851 * Returns: (transfer none): the #GstElementFactory used for creating this
2852 * element. no refcounting is needed.
2855 gst_element_get_factory (GstElement * element)
2857 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2859 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2863 gst_element_dispose (GObject * object)
2865 GstElement *element = GST_ELEMENT_CAST (object);
2868 GstElementClass *oclass;
2871 oclass = GST_ELEMENT_GET_CLASS (element);
2873 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2875 if (GST_STATE (element) != GST_STATE_NULL)
2878 /* start by releasing all request pads, this might also remove some dynamic
2880 walk = element->pads;
2882 GstPad *pad = GST_PAD_CAST (walk->data);
2886 if (oclass->release_pad && GST_PAD_PAD_TEMPLATE (pad) &&
2887 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
2888 == GST_PAD_REQUEST) {
2889 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2890 "removing request pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2891 oclass->release_pad (element, pad);
2893 /* in case the release_pad function removed the next pad too */
2894 if (walk && g_list_position (element->pads, walk) == -1)
2895 walk = element->pads;
2898 /* remove the remaining pads */
2899 while (element->pads) {
2900 GstPad *pad = GST_PAD_CAST (element->pads->data);
2901 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2902 "removing pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2903 if (!gst_element_remove_pad (element, pad)) {
2904 /* only happens when someone unparented our pad.. */
2905 g_critical ("failed to remove pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2910 GST_OBJECT_LOCK (element);
2911 clock_p = &element->clock;
2912 bus_p = &element->bus;
2913 gst_object_replace ((GstObject **) clock_p, NULL);
2914 gst_object_replace ((GstObject **) bus_p, NULL);
2915 GST_OBJECT_UNLOCK (element);
2917 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2919 G_OBJECT_CLASS (parent_class)->dispose (object);
2928 is_locked = GST_ELEMENT_IS_LOCKED_STATE (element);
2930 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2932 "You need to explicitly set elements to the NULL state before\n"
2933 "dropping the final reference, to allow them to clean up.\n"
2934 "This problem may also be caused by a refcounting bug in the\n"
2935 "application or some element.\n",
2936 GST_OBJECT_NAME (element),
2937 gst_element_state_get_name (GST_STATE (element)),
2938 is_locked ? " (locked)" : "");
2944 gst_element_finalize (GObject * object)
2946 GstElement *element = GST_ELEMENT_CAST (object);
2948 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2950 g_cond_clear (&element->state_cond);
2951 g_rec_mutex_clear (&element->state_lock);
2953 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2955 G_OBJECT_CLASS (parent_class)->finalize (object);
2959 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2963 g_return_if_fail (GST_IS_ELEMENT (element));
2965 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2967 GST_OBJECT_LOCK (element);
2968 bus_p = &GST_ELEMENT_BUS (element);
2969 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
2970 GST_OBJECT_UNLOCK (element);
2974 * gst_element_set_bus:
2975 * @element: a #GstElement to set the bus of.
2976 * @bus: (transfer none): the #GstBus to set.
2978 * Sets the bus of the element. Increases the refcount on the bus.
2979 * For internal use only, unless you're testing elements.
2984 gst_element_set_bus (GstElement * element, GstBus * bus)
2986 GstElementClass *oclass;
2988 g_return_if_fail (GST_IS_ELEMENT (element));
2990 oclass = GST_ELEMENT_GET_CLASS (element);
2992 if (oclass->set_bus)
2993 oclass->set_bus (element, bus);
2997 * gst_element_get_bus:
2998 * @element: a #GstElement to get the bus of.
3000 * Returns the bus of the element. Note that only a #GstPipeline will provide a
3001 * bus for the application.
3003 * Returns: (transfer full): the element's #GstBus. unref after usage.
3008 gst_element_get_bus (GstElement * element)
3010 GstBus *result = NULL;
3012 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3014 GST_OBJECT_LOCK (element);
3015 if ((result = GST_ELEMENT_BUS (element)))
3016 gst_object_ref (result);
3017 GST_OBJECT_UNLOCK (element);
3019 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,
3026 * gst_element_set_context:
3027 * @element: a #GstElement to set the context of.
3028 * @context: (transfer none): the #GstContext to set.
3030 * Sets the context of the element. Increases the refcount of the context.
3035 gst_element_set_context (GstElement * element, GstContext * context)
3037 GstElementClass *oclass;
3039 g_return_if_fail (GST_IS_ELEMENT (element));
3041 oclass = GST_ELEMENT_GET_CLASS (element);
3043 GST_CAT_DEBUG_OBJECT (GST_CAT_CONTEXT, element,
3044 "set context %p %" GST_PTR_FORMAT, context,
3045 gst_context_get_structure (context));
3047 if (oclass->set_context)
3048 oclass->set_context (element, context);