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"
93 #include "gsttracerutils.h"
95 #include "gst-i18n-lib.h"
96 #include "glib-compat-private.h"
98 #ifndef GST_DISABLE_GST_DEBUG
99 #include "printf/printf.h"
102 /* Element signals and args */
118 static void gst_element_class_init (GstElementClass * klass);
119 static void gst_element_init (GstElement * element);
120 static void gst_element_base_class_init (gpointer g_class);
122 static void gst_element_constructed (GObject * object);
123 static void gst_element_dispose (GObject * object);
124 static void gst_element_finalize (GObject * object);
126 static GstStateChangeReturn gst_element_change_state_func (GstElement * element,
127 GstStateChange transition);
128 static GstStateChangeReturn gst_element_get_state_func (GstElement * element,
129 GstState * state, GstState * pending, GstClockTime timeout);
130 static GstStateChangeReturn gst_element_set_state_func (GstElement * element,
132 static gboolean gst_element_set_clock_func (GstElement * element,
134 static void gst_element_set_bus_func (GstElement * element, GstBus * bus);
135 static gboolean gst_element_post_message_default (GstElement * element,
136 GstMessage * message);
137 static void gst_element_set_context_default (GstElement * element,
138 GstContext * context);
140 static gboolean gst_element_default_send_event (GstElement * element,
142 static gboolean gst_element_default_query (GstElement * element,
145 static GstPadTemplate
146 * gst_element_class_get_request_pad_template (GstElementClass *
147 element_class, const gchar * name);
149 static void gst_element_call_async_func (gpointer data, gpointer user_data);
151 static GstObjectClass *parent_class = NULL;
152 static guint gst_element_signals[LAST_SIGNAL] = { 0 };
154 static GThreadPool *gst_element_pool = NULL;
156 /* this is used in gstelementfactory.c:gst_element_register() */
157 GQuark __gst_elementclass_factory = 0;
160 gst_element_get_type (void)
162 static volatile gsize gst_element_type = 0;
164 if (g_once_init_enter (&gst_element_type)) {
166 static const GTypeInfo element_info = {
167 sizeof (GstElementClass),
168 gst_element_base_class_init,
169 NULL, /* base_class_finalize */
170 (GClassInitFunc) gst_element_class_init,
175 (GInstanceInitFunc) gst_element_init,
179 _type = g_type_register_static (GST_TYPE_OBJECT, "GstElement",
180 &element_info, G_TYPE_FLAG_ABSTRACT);
182 __gst_elementclass_factory =
183 g_quark_from_static_string ("GST_ELEMENTCLASS_FACTORY");
184 g_once_init_leave (&gst_element_type, _type);
186 return gst_element_type;
190 gst_element_setup_thread_pool (void)
194 GST_DEBUG ("creating element thread pool");
196 g_thread_pool_new ((GFunc) gst_element_call_async_func, NULL, -1, FALSE,
199 g_critical ("could not alloc threadpool %s", err->message);
200 g_clear_error (&err);
205 gst_element_class_init (GstElementClass * klass)
207 GObjectClass *gobject_class;
209 gobject_class = (GObjectClass *) klass;
211 parent_class = g_type_class_peek_parent (klass);
214 * GstElement::pad-added:
215 * @gstelement: the object which received the signal
216 * @new_pad: the pad that has been added
218 * a new #GstPad has been added to the element. Note that this signal will
219 * usually be emitted from the context of the streaming thread. Also keep in
220 * mind that if you add new elements to the pipeline in the signal handler
221 * you will need to set them to the desired target state with
222 * gst_element_set_state() or gst_element_sync_state_with_parent().
224 gst_element_signals[PAD_ADDED] =
225 g_signal_new ("pad-added", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
226 G_STRUCT_OFFSET (GstElementClass, pad_added), NULL, NULL,
227 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
229 * GstElement::pad-removed:
230 * @gstelement: the object which received the signal
231 * @old_pad: the pad that has been removed
233 * a #GstPad has been removed from the element
235 gst_element_signals[PAD_REMOVED] =
236 g_signal_new ("pad-removed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
237 G_STRUCT_OFFSET (GstElementClass, pad_removed), NULL, NULL,
238 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
240 * GstElement::no-more-pads:
241 * @gstelement: the object which received the signal
243 * This signals that the element will not generate more dynamic pads.
244 * Note that this signal will usually be emitted from the context of
245 * the streaming thread.
247 gst_element_signals[NO_MORE_PADS] =
248 g_signal_new ("no-more-pads", G_TYPE_FROM_CLASS (klass),
249 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstElementClass, no_more_pads), NULL,
250 NULL, g_cclosure_marshal_generic, G_TYPE_NONE, 0);
252 gobject_class->dispose = gst_element_dispose;
253 gobject_class->finalize = gst_element_finalize;
254 gobject_class->constructed = gst_element_constructed;
256 klass->change_state = GST_DEBUG_FUNCPTR (gst_element_change_state_func);
257 klass->set_state = GST_DEBUG_FUNCPTR (gst_element_set_state_func);
258 klass->get_state = GST_DEBUG_FUNCPTR (gst_element_get_state_func);
259 klass->set_clock = GST_DEBUG_FUNCPTR (gst_element_set_clock_func);
260 klass->set_bus = GST_DEBUG_FUNCPTR (gst_element_set_bus_func);
261 klass->query = GST_DEBUG_FUNCPTR (gst_element_default_query);
262 klass->send_event = GST_DEBUG_FUNCPTR (gst_element_default_send_event);
263 klass->numpadtemplates = 0;
264 klass->post_message = GST_DEBUG_FUNCPTR (gst_element_post_message_default);
265 klass->set_context = GST_DEBUG_FUNCPTR (gst_element_set_context_default);
267 klass->elementfactory = NULL;
269 gst_element_setup_thread_pool ();
273 gst_element_base_class_init (gpointer g_class)
275 GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
276 GList *node, *padtemplates;
278 /* Copy the element details here so elements can inherit the
279 * details from their base class and classes only need to set
280 * the details in class_init instead of base_init */
281 element_class->metadata =
282 element_class->metadata ? gst_structure_copy (element_class->metadata) :
283 gst_structure_new_empty ("metadata");
285 /* Copy the pad templates so elements inherit them
286 * from their base class but elements can add pad templates in class_init
287 * instead of base_init.
289 padtemplates = g_list_copy (element_class->padtemplates);
290 for (node = padtemplates; node != NULL; node = node->next) {
291 GstPadTemplate *tmpl = (GstPadTemplate *) node->data;
292 gst_object_ref (tmpl);
294 element_class->padtemplates = padtemplates;
296 /* set the factory, see gst_element_register() */
297 element_class->elementfactory =
298 g_type_get_qdata (G_TYPE_FROM_CLASS (element_class),
299 __gst_elementclass_factory);
300 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "type %s : factory %p",
301 G_OBJECT_CLASS_NAME (element_class), element_class->elementfactory);
305 gst_element_init (GstElement * element)
307 GST_STATE (element) = GST_STATE_NULL;
308 GST_STATE_TARGET (element) = GST_STATE_NULL;
309 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
310 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
311 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
313 g_rec_mutex_init (&element->state_lock);
314 g_cond_init (&element->state_cond);
318 gst_element_constructed (GObject * object)
320 GST_TRACER_ELEMENT_NEW (GST_ELEMENT_CAST (object));
321 G_OBJECT_CLASS (parent_class)->constructed (object);
325 * gst_element_release_request_pad:
326 * @element: a #GstElement to release the request pad of.
327 * @pad: the #GstPad to release.
329 * Makes the element free the previously requested pad as obtained
330 * with gst_element_request_pad().
332 * This does not unref the pad. If the pad was created by using
333 * gst_element_request_pad(), gst_element_release_request_pad() needs to be
334 * followed by gst_object_unref() to free the @pad.
339 gst_element_release_request_pad (GstElement * element, GstPad * pad)
341 GstElementClass *oclass;
343 g_return_if_fail (GST_IS_ELEMENT (element));
344 g_return_if_fail (GST_IS_PAD (pad));
345 g_return_if_fail (GST_PAD_PAD_TEMPLATE (pad) == NULL ||
346 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad)) ==
349 oclass = GST_ELEMENT_GET_CLASS (element);
351 /* if the element implements a custom release function we call that, else we
352 * simply remove the pad from the element */
353 if (oclass->release_pad)
354 oclass->release_pad (element, pad);
356 gst_element_remove_pad (element, pad);
360 * gst_element_provide_clock:
361 * @element: a #GstElement to query
363 * Get the clock provided by the given element.
364 * <note>An element is only required to provide a clock in the PAUSED
365 * state. Some elements can provide a clock in other states.</note>
367 * Returns: (transfer full) (nullable): the GstClock provided by the
368 * element or %NULL if no clock could be provided. Unref after usage.
373 gst_element_provide_clock (GstElement * element)
375 GstClock *result = NULL;
376 GstElementClass *oclass;
378 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
380 oclass = GST_ELEMENT_GET_CLASS (element);
382 if (oclass->provide_clock)
383 result = oclass->provide_clock (element);
389 gst_element_set_clock_func (GstElement * element, GstClock * clock)
393 GST_OBJECT_LOCK (element);
394 clock_p = &element->clock;
395 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
396 GST_OBJECT_UNLOCK (element);
402 * gst_element_set_clock:
403 * @element: a #GstElement to set the clock for.
404 * @clock: the #GstClock to set for the element.
406 * Sets the clock for the element. This function increases the
407 * refcount on the clock. Any previously set clock on the object
410 * Returns: %TRUE if the element accepted the clock. An element can refuse a
411 * clock when it, for example, is not able to slave its internal clock to the
412 * @clock or when it requires a specific clock to operate.
417 gst_element_set_clock (GstElement * element, GstClock * clock)
419 GstElementClass *oclass;
420 gboolean res = FALSE;
422 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
423 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
425 oclass = GST_ELEMENT_GET_CLASS (element);
427 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
429 if (oclass->set_clock)
430 res = oclass->set_clock (element, clock);
436 * gst_element_get_clock:
437 * @element: a #GstElement to get the clock of.
439 * Gets the currently configured clock of the element. This is the clock as was
440 * last set with gst_element_set_clock().
442 * Elements in a pipeline will only have their clock set when the
443 * pipeline is in the PLAYING state.
445 * Returns: (transfer full): the #GstClock of the element. unref after usage.
450 gst_element_get_clock (GstElement * element)
454 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
456 GST_OBJECT_LOCK (element);
457 if ((result = element->clock))
458 gst_object_ref (result);
459 GST_OBJECT_UNLOCK (element);
465 * gst_element_set_base_time:
466 * @element: a #GstElement.
467 * @time: the base time to set.
469 * Set the base time of an element. See gst_element_get_base_time().
474 gst_element_set_base_time (GstElement * element, GstClockTime time)
478 g_return_if_fail (GST_IS_ELEMENT (element));
480 GST_OBJECT_LOCK (element);
481 old = element->base_time;
482 element->base_time = time;
483 GST_OBJECT_UNLOCK (element);
485 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
486 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
487 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
491 * gst_element_get_base_time:
492 * @element: a #GstElement.
494 * Returns the base time of the element. The base time is the
495 * absolute time of the clock when this element was last put to
496 * PLAYING. Subtracting the base time from the clock time gives
497 * the running time of the element.
499 * Returns: the base time of the element.
504 gst_element_get_base_time (GstElement * element)
508 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
510 GST_OBJECT_LOCK (element);
511 result = element->base_time;
512 GST_OBJECT_UNLOCK (element);
518 * gst_element_set_start_time:
519 * @element: a #GstElement.
520 * @time: the base time to set.
522 * Set the start time of an element. The start time of the element is the
523 * running time of the element when it last went to the PAUSED state. In READY
524 * or after a flushing seek, it is set to 0.
526 * Toplevel elements like #GstPipeline will manage the start_time and
527 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
528 * on such a toplevel element will disable the distribution of the base_time to
529 * the children and can be useful if the application manages the base_time
530 * itself, for example if you want to synchronize capture from multiple
531 * pipelines, and you can also ensure that the pipelines have the same clock.
536 gst_element_set_start_time (GstElement * element, GstClockTime time)
540 g_return_if_fail (GST_IS_ELEMENT (element));
542 GST_OBJECT_LOCK (element);
543 old = GST_ELEMENT_START_TIME (element);
544 GST_ELEMENT_START_TIME (element) = time;
545 GST_OBJECT_UNLOCK (element);
547 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
548 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
549 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
553 * gst_element_get_start_time:
554 * @element: a #GstElement.
556 * Returns the start time of the element. The start time is the
557 * running time of the clock when this element was last put to PAUSED.
559 * Usually the start_time is managed by a toplevel element such as
564 * Returns: the start time of the element.
567 gst_element_get_start_time (GstElement * element)
571 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
573 GST_OBJECT_LOCK (element);
574 result = GST_ELEMENT_START_TIME (element);
575 GST_OBJECT_UNLOCK (element);
582 * gst_element_set_index:
583 * @element: a #GstElement.
584 * @index: (transfer none): a #GstIndex.
586 * Set @index on the element. The refcount of the index
587 * will be increased, any previously set index is unreffed.
592 gst_element_set_index (GstElement * element, GstIndex * index)
594 GstElementClass *oclass;
596 g_return_if_fail (GST_IS_ELEMENT (element));
597 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
599 oclass = GST_ELEMENT_GET_CLASS (element);
601 if (oclass->set_index)
602 oclass->set_index (element, index);
606 * gst_element_get_index:
607 * @element: a #GstElement.
609 * Gets the index from the element.
611 * Returns: (transfer full) (nullable): a #GstIndex or %NULL when no
612 * index was set on the element. unref after usage.
617 gst_element_get_index (GstElement * element)
619 GstElementClass *oclass;
620 GstIndex *result = NULL;
622 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
624 oclass = GST_ELEMENT_GET_CLASS (element);
626 if (oclass->get_index)
627 result = oclass->get_index (element);
634 * gst_element_add_pad:
635 * @element: a #GstElement to add the pad to.
636 * @pad: (transfer full): the #GstPad to add to the element.
638 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
639 * see gst_object_set_parent() for refcounting information.
641 * Pads are not automatically activated so elements should perform the needed
642 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
643 * state. See gst_pad_set_active() for more information about activating pads.
645 * The pad and the element should be unlocked when calling this function.
647 * This function will emit the #GstElement::pad-added signal on the element.
649 * Returns: %TRUE if the pad could be added. This function can fail when
650 * a pad with the same name already existed or the pad already had another
656 gst_element_add_pad (GstElement * element, GstPad * pad)
661 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
662 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
664 /* locking pad to look at the name */
665 GST_OBJECT_LOCK (pad);
666 pad_name = g_strdup (GST_PAD_NAME (pad));
667 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
668 GST_STR_NULL (pad_name));
669 active = GST_PAD_IS_ACTIVE (pad);
670 GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_NEED_PARENT);
671 GST_OBJECT_UNLOCK (pad);
673 /* then check to see if there's already a pad by that name here */
674 GST_OBJECT_LOCK (element);
675 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
678 /* try to set the pad's parent */
679 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
680 GST_OBJECT_CAST (element))))
683 /* check for active pads */
684 if (!active && (GST_STATE (element) > GST_STATE_READY ||
685 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
686 g_warning ("adding inactive pad '%s' to running element '%s', you need to "
687 "use gst_pad_set_active(pad,TRUE) before adding it.",
688 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
689 gst_pad_set_active (pad, TRUE);
694 /* add it to the list */
695 switch (gst_pad_get_direction (pad)) {
697 element->srcpads = g_list_append (element->srcpads, pad);
698 element->numsrcpads++;
701 element->sinkpads = g_list_append (element->sinkpads, pad);
702 element->numsinkpads++;
707 element->pads = g_list_append (element->pads, pad);
709 element->pads_cookie++;
710 GST_OBJECT_UNLOCK (element);
712 /* emit the PAD_ADDED signal */
713 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
714 GST_TRACER_ELEMENT_ADD_PAD (element, pad);
720 g_critical ("Padname %s is not unique in element %s, not adding",
721 pad_name, GST_ELEMENT_NAME (element));
722 GST_OBJECT_UNLOCK (element);
729 ("Pad %s already has parent when trying to add to element %s",
730 pad_name, GST_ELEMENT_NAME (element));
731 GST_OBJECT_UNLOCK (element);
737 GST_OBJECT_LOCK (pad);
739 ("Trying to add pad %s to element %s, but it has no direction",
740 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
741 GST_OBJECT_UNLOCK (pad);
742 GST_OBJECT_UNLOCK (element);
748 * gst_element_remove_pad:
749 * @element: a #GstElement to remove pad from.
750 * @pad: (transfer full): the #GstPad to remove from the element.
752 * Removes @pad from @element. @pad will be destroyed if it has not been
753 * referenced elsewhere using gst_object_unparent().
755 * This function is used by plugin developers and should not be used
756 * by applications. Pads that were dynamically requested from elements
757 * with gst_element_request_pad() should be released with the
758 * gst_element_release_request_pad() function instead.
760 * Pads are not automatically deactivated so elements should perform the needed
761 * steps to deactivate the pad in case this pad is removed in the PAUSED or
762 * PLAYING state. See gst_pad_set_active() for more information about
765 * The pad and the element should be unlocked when calling this function.
767 * This function will emit the #GstElement::pad-removed signal on the element.
769 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
770 * pad does not belong to the provided element.
775 gst_element_remove_pad (GstElement * element, GstPad * pad)
779 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
780 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
782 /* locking pad to look at the name and parent */
783 GST_OBJECT_LOCK (pad);
784 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
785 GST_STR_NULL (GST_PAD_NAME (pad)));
787 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
789 GST_OBJECT_UNLOCK (pad);
792 if ((peer = gst_pad_get_peer (pad))) {
793 /* window for MT unsafeness, someone else could unlink here
794 * and then we call unlink with wrong pads. The unlink
795 * function would catch this and safely return failed. */
796 if (GST_PAD_IS_SRC (pad))
797 gst_pad_unlink (pad, peer);
799 gst_pad_unlink (peer, pad);
801 gst_object_unref (peer);
804 GST_OBJECT_LOCK (element);
805 /* remove it from the list */
806 switch (gst_pad_get_direction (pad)) {
808 element->srcpads = g_list_remove (element->srcpads, pad);
809 element->numsrcpads--;
812 element->sinkpads = g_list_remove (element->sinkpads, pad);
813 element->numsinkpads--;
816 g_critical ("Removing pad without direction???");
819 element->pads = g_list_remove (element->pads, pad);
821 element->pads_cookie++;
822 GST_OBJECT_UNLOCK (element);
824 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
825 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
826 GST_TRACER_ELEMENT_REMOVE_PAD (element, pad);
827 gst_object_unparent (GST_OBJECT_CAST (pad));
834 /* locking order is element > pad */
835 GST_OBJECT_UNLOCK (pad);
837 GST_OBJECT_LOCK (element);
838 GST_OBJECT_LOCK (pad);
839 g_critical ("Padname %s:%s does not belong to element %s when removing",
840 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
841 GST_OBJECT_UNLOCK (pad);
842 GST_OBJECT_UNLOCK (element);
848 * gst_element_no_more_pads:
849 * @element: a #GstElement
851 * Use this function to signal that the element does not expect any more pads
852 * to show up in the current pipeline. This function should be called whenever
853 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
854 * pad templates use this in combination with autopluggers to figure out that
855 * the element is done initializing its pads.
857 * This function emits the #GstElement::no-more-pads signal.
862 gst_element_no_more_pads (GstElement * element)
864 g_return_if_fail (GST_IS_ELEMENT (element));
866 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
870 pad_compare_name (GstPad * pad1, const gchar * name)
874 GST_OBJECT_LOCK (pad1);
875 result = strcmp (GST_PAD_NAME (pad1), name);
876 GST_OBJECT_UNLOCK (pad1);
882 * gst_element_get_static_pad:
883 * @element: a #GstElement to find a static pad of.
884 * @name: the name of the static #GstPad to retrieve.
886 * Retrieves a pad from @element by name. This version only retrieves
887 * already-existing (i.e. 'static') pads.
889 * Returns: (transfer full) (nullable): the requested #GstPad if
890 * found, otherwise %NULL. unref after usage.
895 gst_element_get_static_pad (GstElement * element, const gchar * name)
898 GstPad *result = NULL;
900 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
901 g_return_val_if_fail (name != NULL, NULL);
903 GST_OBJECT_LOCK (element);
905 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
907 result = GST_PAD_CAST (find->data);
908 gst_object_ref (result);
911 if (result == NULL) {
912 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
913 name, GST_ELEMENT_NAME (element));
915 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
916 GST_ELEMENT_NAME (element), name);
918 GST_OBJECT_UNLOCK (element);
924 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
925 const gchar * name, const GstCaps * caps)
927 GstPad *newpad = NULL;
928 GstElementClass *oclass;
930 oclass = GST_ELEMENT_GET_CLASS (element);
932 #ifndef G_DISABLE_CHECKS
933 /* Some sanity checking here */
937 /* Is this the template name? */
938 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
939 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
941 const gchar *str, *data;
944 /* Otherwise check if it's a valid name for the name template */
945 str = strchr (templ->name_template, '%');
946 g_return_val_if_fail (str != NULL, NULL);
947 g_return_val_if_fail (strncmp (templ->name_template, name,
948 str - templ->name_template) == 0, NULL);
949 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
951 data = name + (str - templ->name_template);
953 /* Can either be %s or %d or %u, do sanity checking for %d */
954 if (*(str + 1) == 'd') {
958 tmp = g_ascii_strtoll (data, &endptr, 10);
959 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
960 && *endptr == '\0', NULL);
961 } else if (*(str + 1) == 'u') {
965 tmp = g_ascii_strtoull (data, &endptr, 10);
966 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
970 pad = gst_element_get_static_pad (element, name);
972 gst_object_unref (pad);
973 /* FIXME 2.0: Change this to g_return_val_if_fail() */
974 g_critical ("Element %s already has a pad named %s, the behaviour of "
975 " gst_element_get_request_pad() for existing pads is undefined!",
976 GST_ELEMENT_NAME (element), name);
981 if (oclass->request_new_pad)
982 newpad = (oclass->request_new_pad) (element, templ, name, caps);
985 gst_object_ref (newpad);
991 * gst_element_get_request_pad:
992 * @element: a #GstElement to find a request pad of.
993 * @name: the name of the request #GstPad to retrieve.
995 * Retrieves a pad from the element by name (e.g. "src_\%d"). This version only
996 * retrieves request pads. The pad should be released with
997 * gst_element_release_request_pad().
999 * This method is slower than manually getting the pad template and calling
1000 * gst_element_request_pad() if the pads should have a specific name (e.g.
1001 * @name is "src_1" instead of "src_\%u").
1003 * Returns: (transfer full) (nullable): requested #GstPad if found,
1004 * otherwise %NULL. Release after usage.
1007 gst_element_get_request_pad (GstElement * element, const gchar * name)
1009 GstPadTemplate *templ = NULL;
1011 const gchar *req_name = NULL;
1012 gboolean templ_found = FALSE;
1015 gchar *str, *endptr = NULL;
1016 GstElementClass *class;
1018 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1019 g_return_val_if_fail (name != NULL, NULL);
1021 class = GST_ELEMENT_GET_CLASS (element);
1023 /* if the name contains a %, we assume it's the complete template name. Get
1024 * the template and try to get a pad */
1025 if (strstr (name, "%")) {
1026 templ = gst_element_class_get_request_pad_template (class, name);
1031 /* there is no % in the name, try to find a matching template */
1032 list = class->padtemplates;
1033 while (!templ_found && list) {
1034 templ = (GstPadTemplate *) list->data;
1035 if (templ->presence == GST_PAD_REQUEST) {
1036 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1037 templ->name_template);
1038 /* see if we find an exact match */
1039 if (strcmp (name, templ->name_template) == 0) {
1044 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1045 and %d and %u, occurring at the end of the name_template, are the only
1047 else if ((str = strchr (templ->name_template, '%'))
1048 && strncmp (templ->name_template, name,
1049 str - templ->name_template) == 0
1050 && strlen (name) > str - templ->name_template) {
1051 data = name + (str - templ->name_template);
1052 if (*(str + 1) == 'd') {
1056 tmp = strtol (data, &endptr, 10);
1057 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1063 } else if (*(str + 1) == 'u') {
1067 tmp = strtoul (data, &endptr, 10);
1068 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1088 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1094 * gst_element_request_pad: (virtual request_new_pad)
1095 * @element: a #GstElement to find a request pad of.
1096 * @templ: a #GstPadTemplate of which we want a pad of.
1097 * @name: (transfer none) (allow-none): the name of the request #GstPad
1098 * to retrieve. Can be %NULL.
1099 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1100 * request. Can be %NULL.
1102 * Retrieves a request pad from the element according to the provided template.
1103 * Pad templates can be looked up using
1104 * gst_element_factory_get_static_pad_templates().
1106 * The pad should be released with gst_element_release_request_pad().
1108 * Returns: (transfer full) (nullable): requested #GstPad if found,
1109 * otherwise %NULL. Release after usage.
1112 gst_element_request_pad (GstElement * element,
1113 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1115 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1116 g_return_val_if_fail (templ != NULL, NULL);
1117 g_return_val_if_fail (templ->presence == GST_PAD_REQUEST, NULL);
1119 return _gst_element_request_pad (element, templ, name, caps);
1122 static GstIterator *
1123 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1125 GstIterator *result;
1127 GST_OBJECT_LOCK (element);
1128 result = gst_iterator_new_list (GST_TYPE_PAD,
1129 GST_OBJECT_GET_LOCK (element),
1130 &element->pads_cookie, padlist, (GObject *) element, NULL);
1131 GST_OBJECT_UNLOCK (element);
1137 * gst_element_iterate_pads:
1138 * @element: a #GstElement to iterate pads of.
1140 * Retrieves an iterator of @element's pads. The iterator should
1141 * be freed after usage. Also more specialized iterators exists such as
1142 * gst_element_iterate_src_pads() or gst_element_iterate_sink_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_pads (GstElement * element)
1154 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1156 return gst_element_iterate_pad_list (element, &element->pads);
1160 * gst_element_iterate_src_pads:
1161 * @element: a #GstElement.
1163 * Retrieves an iterator of @element's source 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_src_pads (GstElement * element)
1175 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1177 return gst_element_iterate_pad_list (element, &element->srcpads);
1181 * gst_element_iterate_sink_pads:
1182 * @element: a #GstElement.
1184 * Retrieves an iterator of @element's sink pads.
1186 * The order of pads returned by the iterator will be the order in which
1187 * the pads were added to the element.
1189 * Returns: (transfer full): the #GstIterator of #GstPad.
1194 gst_element_iterate_sink_pads (GstElement * element)
1196 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1198 return gst_element_iterate_pad_list (element, &element->sinkpads);
1202 * gst_element_class_add_pad_template:
1203 * @klass: the #GstElementClass to add the pad template to.
1204 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1206 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1207 * functions of classes. If a pad template with the same name as an already
1208 * existing one is added the old one is replaced by the new one.
1212 gst_element_class_add_pad_template (GstElementClass * klass,
1213 GstPadTemplate * templ)
1215 GList *template_list = klass->padtemplates;
1217 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1218 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1220 /* If we already have a pad template with the same name replace the
1222 while (template_list) {
1223 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1225 /* Found pad with the same name, replace and return */
1226 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1227 gst_object_unref (padtempl);
1228 template_list->data = templ;
1231 template_list = g_list_next (template_list);
1234 /* Take ownership of the floating ref */
1235 gst_object_ref_sink (templ);
1237 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1238 klass->numpadtemplates++;
1242 * gst_element_class_add_static_pad_template:
1243 * @klass: the #GstElementClass to add the pad template to.
1244 * @static_templ: #GstStaticPadTemplate to add as pad template to the element class.
1246 * Adds a pad template to an element class based on the static pad template
1247 * @templ. This is mainly used in the _class_init functions of element
1248 * implementations. If a pad template with the same name already exists,
1249 * the old one is replaced by the new one.
1254 gst_element_class_add_static_pad_template (GstElementClass * klass,
1255 GstStaticPadTemplate * static_templ)
1257 gst_element_class_add_pad_template (klass,
1258 gst_static_pad_template_get (static_templ));
1262 * gst_element_class_add_metadata:
1263 * @klass: class to set metadata for
1264 * @key: the key to set
1265 * @value: the value to set
1267 * Set @key with @value as metadata in @klass.
1270 gst_element_class_add_metadata (GstElementClass * klass,
1271 const gchar * key, const gchar * value)
1273 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1274 g_return_if_fail (key != NULL);
1275 g_return_if_fail (value != NULL);
1277 gst_structure_set ((GstStructure *) klass->metadata,
1278 key, G_TYPE_STRING, value, NULL);
1282 * gst_element_class_add_static_metadata:
1283 * @klass: class to set metadata for
1284 * @key: the key to set
1285 * @value: the value to set
1287 * Set @key with @value as metadata in @klass.
1289 * Same as gst_element_class_add_metadata(), but @value must be a static string
1290 * or an inlined string, as it will not be copied. (GStreamer plugins will
1291 * be made resident once loaded, so this function can be used even from
1292 * dynamically loaded plugins.)
1295 gst_element_class_add_static_metadata (GstElementClass * klass,
1296 const gchar * key, const gchar * value)
1298 GValue val = G_VALUE_INIT;
1300 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1301 g_return_if_fail (key != NULL);
1302 g_return_if_fail (value != NULL);
1304 g_value_init (&val, G_TYPE_STRING);
1305 g_value_set_static_string (&val, value);
1306 gst_structure_take_value ((GstStructure *) klass->metadata, key, &val);
1310 * gst_element_class_set_metadata:
1311 * @klass: class to set metadata for
1312 * @longname: The long English name of the element. E.g. "File Sink"
1313 * @classification: String describing the type of element, as an unordered list
1314 * separated with slashes ('/'). See draft-klass.txt of the design docs
1315 * for more details and common types. E.g: "Sink/File"
1316 * @description: Sentence describing the purpose of the element.
1317 * E.g: "Write stream to a file"
1318 * @author: Name and contact details of the author(s). Use \n to separate
1319 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1321 * Sets the detailed information for a #GstElementClass.
1322 * <note>This function is for use in _class_init functions only.</note>
1325 gst_element_class_set_metadata (GstElementClass * klass,
1326 const gchar * longname, const gchar * classification,
1327 const gchar * description, const gchar * author)
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 gst_structure_id_set ((GstStructure *) klass->metadata,
1336 GST_QUARK (ELEMENT_METADATA_LONGNAME), G_TYPE_STRING, longname,
1337 GST_QUARK (ELEMENT_METADATA_KLASS), G_TYPE_STRING, classification,
1338 GST_QUARK (ELEMENT_METADATA_DESCRIPTION), G_TYPE_STRING, description,
1339 GST_QUARK (ELEMENT_METADATA_AUTHOR), G_TYPE_STRING, author, NULL);
1343 * gst_element_class_set_static_metadata:
1344 * @klass: class to set metadata for
1345 * @longname: The long English name of the element. E.g. "File Sink"
1346 * @classification: String describing the type of element, as an unordered list
1347 * separated with slashes ('/'). See draft-klass.txt of the design docs
1348 * for more details and common types. E.g: "Sink/File"
1349 * @description: Sentence describing the purpose of the element.
1350 * E.g: "Write stream to a file"
1351 * @author: Name and contact details of the author(s). Use \n to separate
1352 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1354 * Sets the detailed information for a #GstElementClass.
1355 * <note>This function is for use in _class_init functions only.</note>
1357 * Same as gst_element_class_set_metadata(), but @longname, @classification,
1358 * @description, and @author must be static strings or inlined strings, as
1359 * they will not be copied. (GStreamer plugins will be made resident once
1360 * loaded, so this function can be used even from dynamically loaded plugins.)
1363 gst_element_class_set_static_metadata (GstElementClass * klass,
1364 const gchar * longname, const gchar * classification,
1365 const gchar * description, const gchar * author)
1367 GstStructure *s = (GstStructure *) klass->metadata;
1368 GValue val = G_VALUE_INIT;
1370 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1371 g_return_if_fail (longname != NULL && *longname != '\0');
1372 g_return_if_fail (classification != NULL && *classification != '\0');
1373 g_return_if_fail (description != NULL && *description != '\0');
1374 g_return_if_fail (author != NULL && *author != '\0');
1376 g_value_init (&val, G_TYPE_STRING);
1378 g_value_set_static_string (&val, longname);
1379 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_LONGNAME), &val);
1381 g_value_set_static_string (&val, classification);
1382 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_KLASS), &val);
1384 g_value_set_static_string (&val, description);
1385 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_DESCRIPTION),
1388 g_value_set_static_string (&val, author);
1389 gst_structure_id_take_value (s, GST_QUARK (ELEMENT_METADATA_AUTHOR), &val);
1393 * gst_element_class_get_metadata:
1394 * @klass: class to get metadata for
1395 * @key: the key to get
1397 * Get metadata with @key in @klass.
1399 * Returns: the metadata for @key.
1402 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1404 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1405 g_return_val_if_fail (key != NULL, NULL);
1407 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1411 * gst_element_class_get_pad_template_list:
1412 * @element_class: a #GstElementClass to get pad templates of.
1414 * Retrieves a list of the pad templates associated with @element_class. The
1415 * list must not be modified by the calling code.
1416 * <note>If you use this function in the #GInstanceInitFunc of an object class
1417 * that has subclasses, make sure to pass the g_class parameter of the
1418 * #GInstanceInitFunc here.</note>
1420 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1424 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1426 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1428 return element_class->padtemplates;
1432 * gst_element_class_get_pad_template:
1433 * @element_class: a #GstElementClass to get the pad template of.
1434 * @name: the name of the #GstPadTemplate to get.
1436 * Retrieves a padtemplate from @element_class with the given name.
1437 * <note>If you use this function in the #GInstanceInitFunc of an object class
1438 * that has subclasses, make sure to pass the g_class parameter of the
1439 * #GInstanceInitFunc here.</note>
1441 * Returns: (transfer none) (nullable): the #GstPadTemplate with the
1442 * given name, or %NULL if none was found. No unreferencing is
1446 gst_element_class_get_pad_template (GstElementClass *
1447 element_class, const gchar * name)
1451 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1452 g_return_val_if_fail (name != NULL, NULL);
1454 padlist = element_class->padtemplates;
1457 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1459 if (strcmp (padtempl->name_template, name) == 0)
1462 padlist = g_list_next (padlist);
1468 static GstPadTemplate *
1469 gst_element_class_get_request_pad_template (GstElementClass *
1470 element_class, const gchar * name)
1472 GstPadTemplate *tmpl;
1474 tmpl = gst_element_class_get_pad_template (element_class, name);
1475 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1481 /* get a random pad on element of the given direction.
1482 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1485 gst_element_get_random_pad (GstElement * element,
1486 gboolean need_linked, GstPadDirection dir)
1488 GstPad *result = NULL;
1491 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1495 GST_OBJECT_LOCK (element);
1496 pads = element->srcpads;
1499 GST_OBJECT_LOCK (element);
1500 pads = element->sinkpads;
1503 goto wrong_direction;
1505 for (; pads; pads = g_list_next (pads)) {
1506 GstPad *pad = GST_PAD_CAST (pads->data);
1508 GST_OBJECT_LOCK (pad);
1509 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1510 GST_DEBUG_PAD_NAME (pad));
1512 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1513 /* if we require a linked pad, and it is not linked, continue the
1515 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1516 GST_DEBUG_PAD_NAME (pad));
1517 GST_OBJECT_UNLOCK (pad);
1520 /* found a pad, stop search */
1521 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1522 GST_DEBUG_PAD_NAME (pad));
1523 GST_OBJECT_UNLOCK (pad);
1529 gst_object_ref (result);
1531 GST_OBJECT_UNLOCK (element);
1535 /* ERROR handling */
1538 g_warning ("unknown pad direction %d", dir);
1544 gst_element_default_send_event (GstElement * element, GstEvent * event)
1546 gboolean result = FALSE;
1549 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1550 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK) :
1551 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC);
1554 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1555 "pushing %s event to random %s pad %s:%s",
1556 GST_EVENT_TYPE_NAME (event),
1557 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1558 GST_DEBUG_PAD_NAME (pad));
1560 result = gst_pad_send_event (pad, event);
1561 gst_object_unref (pad);
1563 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1564 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1565 gst_event_unref (event);
1571 * gst_element_send_event:
1572 * @element: a #GstElement to send the event to.
1573 * @event: (transfer full): the #GstEvent to send to the element.
1575 * Sends an event to an element. If the element doesn't implement an
1576 * event handler, the event will be pushed on a random linked sink pad for
1577 * downstream events or a random linked source pad for upstream events.
1579 * This function takes ownership of the provided event so you should
1580 * gst_event_ref() it if you want to reuse the event after this call.
1584 * Returns: %TRUE if the event was handled. Events that trigger a preroll (such
1585 * as flushing seeks and steps) will emit %GST_MESSAGE_ASYNC_DONE.
1588 gst_element_send_event (GstElement * element, GstEvent * event)
1590 GstElementClass *oclass;
1591 gboolean result = FALSE;
1593 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1594 g_return_val_if_fail (event != NULL, FALSE);
1596 oclass = GST_ELEMENT_GET_CLASS (element);
1598 GST_STATE_LOCK (element);
1599 if (oclass->send_event) {
1600 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1601 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1602 result = oclass->send_event (element, event);
1604 gst_event_unref (event);
1606 GST_STATE_UNLOCK (element);
1613 * @element: a #GstElement to send the event to.
1614 * @rate: The new playback rate
1615 * @format: The format of the seek values
1616 * @flags: The optional seek flags.
1617 * @start_type: The type and flags for the new start position
1618 * @start: The value of the new start position
1619 * @stop_type: The type and flags for the new stop position
1620 * @stop: The value of the new stop position
1622 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1623 * the parameters. The seek event is sent to the element using
1624 * gst_element_send_event().
1628 * Returns: %TRUE if the event was handled. Flushing seeks will trigger a
1629 * preroll, which will emit %GST_MESSAGE_ASYNC_DONE.
1632 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1633 GstSeekFlags flags, GstSeekType start_type, gint64 start,
1634 GstSeekType stop_type, gint64 stop)
1639 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1642 gst_event_new_seek (rate, format, flags, start_type, start, stop_type,
1644 result = gst_element_send_event (element, event);
1650 gst_element_default_query (GstElement * element, GstQuery * query)
1652 gboolean result = FALSE;
1655 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1657 result = gst_pad_query (pad, query);
1659 gst_object_unref (pad);
1661 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1663 GstPad *peer = gst_pad_get_peer (pad);
1666 result = gst_pad_query (peer, query);
1668 gst_object_unref (peer);
1670 gst_object_unref (pad);
1677 * gst_element_query:
1678 * @element: a #GstElement to perform the query on.
1679 * @query: (transfer none): the #GstQuery.
1681 * Performs a query on the given element.
1683 * For elements that don't implement a query handler, this function
1684 * forwards the query to a random srcpad or to the peer of a
1685 * random linked sinkpad of this element.
1687 * Please note that some queries might need a running pipeline to work.
1689 * Returns: %TRUE if the query could be performed.
1694 gst_element_query (GstElement * element, GstQuery * query)
1696 GstElementClass *klass;
1697 gboolean res = FALSE;
1699 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1700 g_return_val_if_fail (query != NULL, FALSE);
1702 GST_TRACER_ELEMENT_QUERY_PRE (element, query);
1704 klass = GST_ELEMENT_GET_CLASS (element);
1706 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1707 GST_ELEMENT_NAME (element));
1708 res = klass->query (element, query);
1711 GST_TRACER_ELEMENT_QUERY_POST (element, query, res);
1716 gst_element_post_message_default (GstElement * element, GstMessage * message)
1719 gboolean result = FALSE;
1721 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1722 g_return_val_if_fail (message != NULL, FALSE);
1724 GST_OBJECT_LOCK (element);
1727 if (G_UNLIKELY (bus == NULL))
1730 gst_object_ref (bus);
1731 GST_OBJECT_UNLOCK (element);
1733 /* we release the element lock when posting the message so that any
1734 * (synchronous) message handlers can operate on the element */
1735 result = gst_bus_post (bus, message);
1736 gst_object_unref (bus);
1743 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1744 "not posting message %p: no bus", message);
1745 GST_OBJECT_UNLOCK (element);
1746 gst_message_unref (message);
1752 * gst_element_post_message:
1753 * @element: a #GstElement posting the message
1754 * @message: (transfer full): a #GstMessage to post
1756 * Post a message on the element's #GstBus. This function takes ownership of the
1757 * message; if you want to access the message after this call, you should add an
1758 * additional reference before calling.
1760 * Returns: %TRUE if the message was successfully posted. The function returns
1761 * %FALSE if the element did not have a bus.
1766 gst_element_post_message (GstElement * element, GstMessage * message)
1768 GstElementClass *klass;
1769 gboolean res = FALSE;
1771 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1772 g_return_val_if_fail (message != NULL, FALSE);
1774 GST_TRACER_ELEMENT_POST_MESSAGE_PRE (element, message);
1776 klass = GST_ELEMENT_GET_CLASS (element);
1777 if (klass->post_message)
1778 res = klass->post_message (element, message);
1780 gst_message_unref (message);
1782 GST_TRACER_ELEMENT_POST_MESSAGE_POST (element, res);
1787 * _gst_element_error_printf:
1788 * @format: (allow-none): the printf-like format to use, or %NULL
1790 * This function is only used internally by the gst_element_error() macro.
1792 * Returns: (transfer full) (nullable): a newly allocated string, or
1793 * %NULL if the format was %NULL or ""
1798 _gst_element_error_printf (const gchar * format, ...)
1809 va_start (args, format);
1811 len = __gst_vasprintf (&buffer, format, args);
1822 * gst_element_message_full:
1823 * @element: a #GstElement to send message from
1824 * @type: the #GstMessageType
1825 * @domain: the GStreamer GError domain this message belongs to
1826 * @code: the GError code belonging to the domain
1827 * @text: (allow-none) (transfer full): an allocated text string to be used
1828 * as a replacement for the default message connected to code,
1830 * @debug: (allow-none) (transfer full): an allocated debug message to be
1831 * used as a replacement for the default debugging information,
1833 * @file: the source code file where the error was generated
1834 * @function: the source code function where the error was generated
1835 * @line: the source code line where the error was generated
1837 * Post an error, warning or info message on the bus from inside an element.
1839 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1840 * #GST_MESSAGE_INFO.
1844 void gst_element_message_full
1845 (GstElement * element, GstMessageType type,
1846 GQuark domain, gint code, gchar * text,
1847 gchar * debug, const gchar * file, const gchar * function, gint line)
1849 GError *gerror = NULL;
1853 gboolean has_debug = TRUE;
1854 GstMessage *message = NULL;
1857 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1858 g_return_if_fail (GST_IS_ELEMENT (element));
1859 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1860 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1862 /* check if we send the given text or the default error text */
1863 if ((text == NULL) || (text[0] == 0)) {
1864 /* text could have come from g_strdup_printf (""); */
1866 sent_text = gst_error_get_message (domain, code);
1870 /* construct a sent_debug with extra information from source */
1871 if ((debug == NULL) || (debug[0] == 0)) {
1872 /* debug could have come from g_strdup_printf (""); */
1876 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1878 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1879 file, line, function, name, debug);
1881 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1882 file, line, function, name);
1886 /* create gerror and post message */
1887 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1889 gerror = g_error_new_literal (domain, code, sent_text);
1892 case GST_MESSAGE_ERROR:
1894 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1896 case GST_MESSAGE_WARNING:
1897 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1900 case GST_MESSAGE_INFO:
1901 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1905 g_assert_not_reached ();
1908 gst_element_post_message (element, message);
1910 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1911 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1914 g_error_free (gerror);
1915 g_free (sent_debug);
1920 * gst_element_is_locked_state:
1921 * @element: a #GstElement.
1923 * Checks if the state of an element is locked.
1924 * If the state of an element is locked, state changes of the parent don't
1925 * affect the element.
1926 * This way you can leave currently unused elements inside bins. Just lock their
1927 * state before changing the state from #GST_STATE_NULL.
1931 * Returns: %TRUE, if the element's state is locked.
1934 gst_element_is_locked_state (GstElement * element)
1938 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1940 GST_OBJECT_LOCK (element);
1941 result = GST_ELEMENT_IS_LOCKED_STATE (element);
1942 GST_OBJECT_UNLOCK (element);
1948 * gst_element_set_locked_state:
1949 * @element: a #GstElement
1950 * @locked_state: %TRUE to lock the element's state
1952 * Locks the state of an element, so state changes of the parent don't affect
1953 * this element anymore.
1957 * Returns: %TRUE if the state was changed, %FALSE if bad parameters were given
1958 * or the elements state-locking needed no change.
1961 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1965 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1967 GST_OBJECT_LOCK (element);
1968 old = GST_ELEMENT_IS_LOCKED_STATE (element);
1970 if (G_UNLIKELY (old == locked_state))
1974 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1975 GST_ELEMENT_NAME (element));
1976 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1978 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1979 GST_ELEMENT_NAME (element));
1980 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1982 GST_OBJECT_UNLOCK (element);
1988 GST_CAT_DEBUG (GST_CAT_STATES,
1989 "elements %s was already in locked state %d",
1990 GST_ELEMENT_NAME (element), old);
1991 GST_OBJECT_UNLOCK (element);
1998 * gst_element_sync_state_with_parent:
1999 * @element: a #GstElement.
2001 * Tries to change the state of the element to the same as its parent.
2002 * If this function returns %FALSE, the state of element is undefined.
2004 * Returns: %TRUE, if the element's state could be synced to the parent's state.
2009 gst_element_sync_state_with_parent (GstElement * element)
2013 GstStateChangeReturn ret;
2015 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
2017 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
2018 GstState parent_current, parent_pending;
2020 GST_OBJECT_LOCK (parent);
2021 parent_current = GST_STATE (parent);
2022 parent_pending = GST_STATE_PENDING (parent);
2023 GST_OBJECT_UNLOCK (parent);
2025 /* set to pending if there is one, else we set it to the current state of
2027 if (parent_pending != GST_STATE_VOID_PENDING)
2028 target = parent_pending;
2030 target = parent_current;
2032 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2033 "syncing state (%s) to parent %s %s (%s, %s)",
2034 gst_element_state_get_name (GST_STATE (element)),
2035 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
2036 gst_element_state_get_name (parent_current),
2037 gst_element_state_get_name (parent_pending));
2039 ret = gst_element_set_state (element, target);
2040 if (ret == GST_STATE_CHANGE_FAILURE)
2043 gst_object_unref (parent);
2047 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
2054 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2055 "syncing state failed (%s)",
2056 gst_element_state_change_return_get_name (ret));
2057 gst_object_unref (parent);
2063 static GstStateChangeReturn
2064 gst_element_get_state_func (GstElement * element,
2065 GstState * state, GstState * pending, GstClockTime timeout)
2067 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2068 GstState old_pending;
2070 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2071 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2073 GST_OBJECT_LOCK (element);
2074 ret = GST_STATE_RETURN (element);
2075 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2076 gst_element_state_change_return_get_name (ret));
2078 /* we got an error, report immediately */
2079 if (ret == GST_STATE_CHANGE_FAILURE)
2082 /* we got no_preroll, report immediately */
2083 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2086 /* no need to wait async if we are not async */
2087 if (ret != GST_STATE_CHANGE_ASYNC)
2090 old_pending = GST_STATE_PENDING (element);
2091 if (old_pending != GST_STATE_VOID_PENDING) {
2095 /* get cookie to detect state changes during waiting */
2096 cookie = element->state_cookie;
2098 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2099 "waiting for element to commit state");
2101 /* we have a pending state change, wait for it to complete */
2102 if (timeout != GST_CLOCK_TIME_NONE) {
2104 /* make timeout absolute */
2105 end_time = g_get_monotonic_time () + (timeout / 1000);
2106 signaled = GST_STATE_WAIT_UNTIL (element, end_time);
2108 GST_STATE_WAIT (element);
2113 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2114 /* timeout triggered */
2115 ret = GST_STATE_CHANGE_ASYNC;
2117 if (cookie != element->state_cookie)
2120 /* could be success or failure */
2121 if (old_pending == GST_STATE (element)) {
2122 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2123 ret = GST_STATE_CHANGE_SUCCESS;
2125 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2126 ret = GST_STATE_CHANGE_FAILURE;
2129 /* if nothing is pending anymore we can return SUCCESS */
2130 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2131 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2132 ret = GST_STATE_CHANGE_SUCCESS;
2138 *state = GST_STATE (element);
2140 *pending = GST_STATE_PENDING (element);
2142 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2143 "state current: %s, pending: %s, result: %s",
2144 gst_element_state_get_name (GST_STATE (element)),
2145 gst_element_state_get_name (GST_STATE_PENDING (element)),
2146 gst_element_state_change_return_get_name (ret));
2147 GST_OBJECT_UNLOCK (element);
2154 *state = GST_STATE_VOID_PENDING;
2156 *pending = GST_STATE_VOID_PENDING;
2158 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2160 GST_OBJECT_UNLOCK (element);
2162 return GST_STATE_CHANGE_FAILURE;
2167 * gst_element_get_state:
2168 * @element: a #GstElement to get the state of.
2169 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2171 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2172 * state. Can be %NULL.
2173 * @timeout: a #GstClockTime to specify the timeout for an async
2174 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2176 * Gets the state of the element.
2178 * For elements that performed an ASYNC state change, as reported by
2179 * gst_element_set_state(), this function will block up to the
2180 * specified timeout value for the state change to complete.
2181 * If the element completes the state change or goes into
2182 * an error, this function returns immediately with a return value of
2183 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2185 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2186 * returns the current and pending state immediately.
2188 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2189 * successfully changed its state but is not able to provide data yet.
2190 * This mostly happens for live sources that only produce data in
2191 * %GST_STATE_PLAYING. While the state change return is equivalent to
2192 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2193 * some sink elements might not be able to complete their state change because
2194 * an element is not producing data to complete the preroll. When setting the
2195 * element to playing, the preroll will complete and playback will start.
2197 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2198 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2199 * element is still performing a state change or
2200 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2204 GstStateChangeReturn
2205 gst_element_get_state (GstElement * element,
2206 GstState * state, GstState * pending, GstClockTime timeout)
2208 GstElementClass *oclass;
2209 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2211 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2213 oclass = GST_ELEMENT_GET_CLASS (element);
2215 if (oclass->get_state)
2216 result = (oclass->get_state) (element, state, pending, timeout);
2222 * gst_element_abort_state:
2223 * @element: a #GstElement to abort the state of.
2225 * Abort the state change of the element. This function is used
2226 * by elements that do asynchronous state changes and find out
2227 * something is wrong.
2229 * This function should be called with the STATE_LOCK held.
2234 gst_element_abort_state (GstElement * element)
2238 #ifndef GST_DISABLE_GST_DEBUG
2242 g_return_if_fail (GST_IS_ELEMENT (element));
2244 GST_OBJECT_LOCK (element);
2245 pending = GST_STATE_PENDING (element);
2247 if (pending == GST_STATE_VOID_PENDING ||
2248 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2249 goto nothing_aborted;
2251 #ifndef GST_DISABLE_GST_DEBUG
2252 old_state = GST_STATE (element);
2254 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2255 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2256 gst_element_state_get_name (pending));
2260 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2262 GST_STATE_BROADCAST (element);
2263 GST_OBJECT_UNLOCK (element);
2269 GST_OBJECT_UNLOCK (element);
2274 /* Not static because GstBin has manual state handling too */
2276 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2277 GstState newstate, GstState pending)
2279 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2280 GstMessage *message;
2282 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2283 "notifying about state-changed %s to %s (%s pending)",
2284 gst_element_state_get_name (oldstate),
2285 gst_element_state_get_name (newstate),
2286 gst_element_state_get_name (pending));
2288 if (klass->state_changed)
2289 klass->state_changed (element, oldstate, newstate, pending);
2291 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2292 oldstate, newstate, pending);
2293 gst_element_post_message (element, message);
2297 * gst_element_continue_state:
2298 * @element: a #GstElement to continue the state change of.
2299 * @ret: The previous state return value
2301 * Commit the state change of the element and proceed to the next
2302 * pending state if any. This function is used
2303 * by elements that do asynchronous state changes.
2304 * The core will normally call this method automatically when an
2305 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2307 * If after calling this method the element still has not reached
2308 * the pending state, the next state change is performed.
2310 * This method is used internally and should normally not be called by plugins
2313 * Returns: The result of the commit state change.
2317 GstStateChangeReturn
2318 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2320 GstStateChangeReturn old_ret;
2321 GstState old_state, old_next;
2322 GstState current, next, pending;
2323 GstStateChange transition;
2325 GST_OBJECT_LOCK (element);
2326 old_ret = GST_STATE_RETURN (element);
2327 GST_STATE_RETURN (element) = ret;
2328 pending = GST_STATE_PENDING (element);
2330 /* check if there is something to commit */
2331 if (pending == GST_STATE_VOID_PENDING)
2332 goto nothing_pending;
2334 old_state = GST_STATE (element);
2335 /* this is the state we should go to next */
2336 old_next = GST_STATE_NEXT (element);
2337 /* update current state */
2338 current = GST_STATE (element) = old_next;
2340 /* see if we reached the final state */
2341 if (pending == current)
2344 next = GST_STATE_GET_NEXT (current, pending);
2345 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2347 GST_STATE_NEXT (element) = next;
2349 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2350 GST_OBJECT_UNLOCK (element);
2352 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2353 "committing state from %s to %s, pending %s, next %s",
2354 gst_element_state_get_name (old_state),
2355 gst_element_state_get_name (old_next),
2356 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2358 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2360 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2361 "continue state change %s to %s, final %s",
2362 gst_element_state_get_name (current),
2363 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2365 ret = gst_element_change_state (element, transition);
2371 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2372 GST_OBJECT_UNLOCK (element);
2377 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2378 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2380 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2381 "completed state change to %s", gst_element_state_get_name (pending));
2382 GST_OBJECT_UNLOCK (element);
2384 /* don't post silly messages with the same state. This can happen
2385 * when an element state is changed to what it already was. For bins
2386 * this can be the result of a lost state, which we check with the
2387 * previous return value.
2388 * We do signal the cond though as a _get_state() might be blocking
2390 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2391 _priv_gst_element_state_changed (element, old_state, old_next,
2392 GST_STATE_VOID_PENDING);
2394 GST_STATE_BROADCAST (element);
2401 * gst_element_lost_state:
2402 * @element: a #GstElement the state is lost of
2404 * Brings the element to the lost state. The current state of the
2405 * element is copied to the pending state so that any call to
2406 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2408 * An ASYNC_START message is posted. If the element was PLAYING, it will
2409 * go to PAUSED. The element will be restored to its PLAYING state by
2410 * the parent pipeline when it prerolls again.
2412 * This is mostly used for elements that lost their preroll buffer
2413 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2414 * they will go to their pending state again when a new preroll buffer is
2415 * queued. This function can only be called when the element is currently
2416 * not in error or an async state change.
2418 * This function is used internally and should normally not be called from
2419 * plugins or applications.
2422 gst_element_lost_state (GstElement * element)
2424 GstState old_state, new_state;
2425 GstMessage *message;
2427 g_return_if_fail (GST_IS_ELEMENT (element));
2429 GST_OBJECT_LOCK (element);
2430 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2433 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2434 goto only_async_start;
2436 old_state = GST_STATE (element);
2438 /* when we were PLAYING, the new state is PAUSED. We will also not
2439 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2440 * when we preroll. */
2441 if (old_state > GST_STATE_PAUSED)
2442 new_state = GST_STATE_PAUSED;
2444 new_state = old_state;
2446 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2447 "lost state of %s to %s", gst_element_state_get_name (old_state),
2448 gst_element_state_get_name (new_state));
2450 GST_STATE (element) = new_state;
2451 GST_STATE_NEXT (element) = new_state;
2452 GST_STATE_PENDING (element) = new_state;
2453 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2454 GST_OBJECT_UNLOCK (element);
2456 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2458 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2459 gst_element_post_message (element, message);
2465 GST_OBJECT_UNLOCK (element);
2470 GST_OBJECT_UNLOCK (element);
2472 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2473 gst_element_post_message (element, message);
2479 * gst_element_set_state:
2480 * @element: a #GstElement to change state of.
2481 * @state: the element's new #GstState.
2483 * Sets the state of the element. This function will try to set the
2484 * requested state by going through all the intermediary states and calling
2485 * the class's state change function for each.
2487 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2488 * element will perform the remainder of the state change asynchronously in
2490 * An application can use gst_element_get_state() to wait for the completion
2491 * of the state change or it can wait for a %GST_MESSAGE_ASYNC_DONE or
2492 * %GST_MESSAGE_STATE_CHANGED on the bus.
2494 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2495 * #GST_STATE_CHANGE_ASYNC.
2497 * Returns: Result of the state change using #GstStateChangeReturn.
2501 GstStateChangeReturn
2502 gst_element_set_state (GstElement * element, GstState state)
2504 GstElementClass *oclass;
2505 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2507 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2509 oclass = GST_ELEMENT_GET_CLASS (element);
2511 if (oclass->set_state)
2512 result = (oclass->set_state) (element, state);
2518 * default set state function, calculates the next state based
2519 * on current state and calls the change_state function
2521 static GstStateChangeReturn
2522 gst_element_set_state_func (GstElement * element, GstState state)
2524 GstState current, next, old_pending;
2525 GstStateChangeReturn ret;
2526 GstStateChange transition;
2527 GstStateChangeReturn old_ret;
2529 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2531 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2532 gst_element_state_get_name (state));
2534 /* state lock is taken to protect the set_state() and get_state()
2535 * procedures, it does not lock any variables. */
2536 GST_STATE_LOCK (element);
2538 /* now calculate how to get to the new state */
2539 GST_OBJECT_LOCK (element);
2540 old_ret = GST_STATE_RETURN (element);
2541 /* previous state change returned an error, remove all pending
2542 * and next states */
2543 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2544 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2545 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2546 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2549 current = GST_STATE (element);
2550 next = GST_STATE_NEXT (element);
2551 old_pending = GST_STATE_PENDING (element);
2553 /* this is the (new) state we should go to. TARGET is the last state we set on
2555 if (state != GST_STATE_TARGET (element)) {
2556 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2557 "setting target state to %s", gst_element_state_get_name (state));
2558 GST_STATE_TARGET (element) = state;
2559 /* increment state cookie so that we can track each state change. We only do
2560 * this if this is actually a new state change. */
2561 element->state_cookie++;
2563 GST_STATE_PENDING (element) = state;
2565 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2566 "current %s, old_pending %s, next %s, old return %s",
2567 gst_element_state_get_name (current),
2568 gst_element_state_get_name (old_pending),
2569 gst_element_state_get_name (next),
2570 gst_element_state_change_return_get_name (old_ret));
2572 /* if the element was busy doing a state change, we just update the
2573 * target state, it'll get to it async then. */
2574 if (old_pending != GST_STATE_VOID_PENDING) {
2575 /* upwards state change will happen ASYNC */
2576 if (old_pending <= state)
2578 /* element is going to this state already */
2579 else if (next == state)
2581 /* element was performing an ASYNC upward state change and
2582 * we request to go downward again. Start from the next pending
2584 else if (next > state
2585 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2589 next = GST_STATE_GET_NEXT (current, state);
2590 /* now we store the next state */
2591 GST_STATE_NEXT (element) = next;
2592 /* mark busy, we need to check that there is actually a state change
2593 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2594 * the default element change_state function has no way to know what the
2595 * old value was... could consider this a FIXME...*/
2596 if (current != next)
2597 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2599 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2601 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2602 "%s: setting state from %s to %s",
2603 (next != state ? "intermediate" : "final"),
2604 gst_element_state_get_name (current), gst_element_state_get_name (next));
2606 /* now signal any waiters, they will error since the cookie was incremented */
2607 GST_STATE_BROADCAST (element);
2609 GST_OBJECT_UNLOCK (element);
2611 ret = gst_element_change_state (element, transition);
2613 GST_STATE_UNLOCK (element);
2615 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2616 gst_element_state_change_return_get_name (ret));
2622 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2623 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2624 "element was busy with async state change");
2625 GST_OBJECT_UNLOCK (element);
2627 GST_STATE_UNLOCK (element);
2629 return GST_STATE_CHANGE_ASYNC;
2634 * gst_element_change_state:
2635 * @element: a #GstElement
2636 * @transition: the requested transition
2638 * Perform @transition on @element.
2640 * This function must be called with STATE_LOCK held and is mainly used
2643 * Returns: the #GstStateChangeReturn of the state transition.
2645 GstStateChangeReturn
2646 gst_element_change_state (GstElement * element, GstStateChange transition)
2648 GstElementClass *oclass;
2649 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2651 oclass = GST_ELEMENT_GET_CLASS (element);
2653 GST_TRACER_ELEMENT_CHANGE_STATE_PRE (element, transition);
2655 /* call the state change function so it can set the state */
2656 if (oclass->change_state)
2657 ret = (oclass->change_state) (element, transition);
2659 ret = GST_STATE_CHANGE_FAILURE;
2661 GST_TRACER_ELEMENT_CHANGE_STATE_POST (element, transition, ret);
2664 case GST_STATE_CHANGE_FAILURE:
2665 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2666 "have FAILURE change_state return");
2667 /* state change failure */
2668 gst_element_abort_state (element);
2670 case GST_STATE_CHANGE_ASYNC:
2674 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2675 "element will change state ASYNC");
2677 target = GST_STATE_TARGET (element);
2679 if (target > GST_STATE_READY)
2682 /* else we just continue the state change downwards */
2683 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2684 "forcing commit state %s <= %s",
2685 gst_element_state_get_name (target),
2686 gst_element_state_get_name (GST_STATE_READY));
2688 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2691 case GST_STATE_CHANGE_SUCCESS:
2692 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2693 "element changed state SUCCESS");
2694 /* we can commit the state now which will proceeed to
2696 ret = gst_element_continue_state (element, ret);
2698 case GST_STATE_CHANGE_NO_PREROLL:
2699 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2700 "element changed state NO_PREROLL");
2701 /* we can commit the state now which will proceeed to
2703 ret = gst_element_continue_state (element, ret);
2706 goto invalid_return;
2709 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2714 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2722 GST_OBJECT_LOCK (element);
2723 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2724 g_critical ("%s: unknown return value %d from a state change function",
2725 GST_ELEMENT_NAME (element), ret);
2727 /* we are in error now */
2728 ret = GST_STATE_CHANGE_FAILURE;
2729 GST_STATE_RETURN (element) = ret;
2730 GST_OBJECT_UNLOCK (element);
2736 /* gst_iterator_fold functions for pads_activate
2737 * Stop the iterator if activating one pad failed, but only if that pad
2738 * has not been removed from the element. */
2740 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2742 GstPad *pad = g_value_get_object (vpad);
2743 gboolean cont = TRUE;
2745 if (!gst_pad_set_active (pad, *active)) {
2746 if (GST_PAD_PARENT (pad) != NULL) {
2748 g_value_set_boolean (ret, FALSE);
2755 /* returns false on error or early cutout of the fold, true if all
2756 * pads in @iter were (de)activated successfully. */
2758 iterator_activate_fold_with_resync (GstIterator * iter,
2759 GstIteratorFoldFunction func, gpointer user_data)
2761 GstIteratorResult ires;
2764 /* no need to unset this later, it's just a boolean */
2765 g_value_init (&ret, G_TYPE_BOOLEAN);
2766 g_value_set_boolean (&ret, TRUE);
2769 ires = gst_iterator_fold (iter, func, &ret, user_data);
2771 case GST_ITERATOR_RESYNC:
2772 /* need to reset the result again */
2773 g_value_set_boolean (&ret, TRUE);
2774 gst_iterator_resync (iter);
2776 case GST_ITERATOR_DONE:
2777 /* all pads iterated, return collected value */
2780 /* iterator returned _ERROR or premature end with _OK,
2781 * mark an error and exit */
2782 g_value_set_boolean (&ret, FALSE);
2787 /* return collected value */
2788 return g_value_get_boolean (&ret);
2791 /* is called with STATE_LOCK
2793 * Pads are activated from source pads to sinkpads.
2796 gst_element_pads_activate (GstElement * element, gboolean active)
2801 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2802 "%s pads", active ? "activate" : "deactivate");
2804 iter = gst_element_iterate_src_pads (element);
2806 iterator_activate_fold_with_resync (iter,
2807 (GstIteratorFoldFunction) activate_pads, &active);
2808 gst_iterator_free (iter);
2809 if (G_UNLIKELY (!res))
2812 iter = gst_element_iterate_sink_pads (element);
2814 iterator_activate_fold_with_resync (iter,
2815 (GstIteratorFoldFunction) activate_pads, &active);
2816 gst_iterator_free (iter);
2817 if (G_UNLIKELY (!res))
2820 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2821 "pad %sactivation successful", active ? "" : "de");
2828 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2829 "pad %sactivation failed", active ? "" : "de");
2834 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2835 "sink pads_activate failed");
2840 /* is called with STATE_LOCK */
2841 static GstStateChangeReturn
2842 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2844 GstState state, next;
2845 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2847 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2849 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2850 next = GST_STATE_TRANSITION_NEXT (transition);
2852 /* if the element already is in the given state, we just return success */
2853 if (next == GST_STATE_VOID_PENDING || state == next)
2856 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2857 "default handler tries setting state from %s to %s (%04x)",
2858 gst_element_state_get_name (state),
2859 gst_element_state_get_name (next), transition);
2861 switch (transition) {
2862 case GST_STATE_CHANGE_NULL_TO_READY:
2864 case GST_STATE_CHANGE_READY_TO_PAUSED:
2865 if (!gst_element_pads_activate (element, TRUE)) {
2866 result = GST_STATE_CHANGE_FAILURE;
2869 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2871 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2873 case GST_STATE_CHANGE_PAUSED_TO_READY:
2874 case GST_STATE_CHANGE_READY_TO_NULL:{
2877 /* deactivate pads in both cases, since they are activated on
2878 ready->paused but the element might not have made it to paused */
2879 if (!gst_element_pads_activate (element, FALSE)) {
2880 result = GST_STATE_CHANGE_FAILURE;
2883 /* Remove all non-persistent contexts */
2884 GST_OBJECT_LOCK (element);
2885 for (l = element->contexts; l;) {
2886 GstContext *context = l->data;
2888 if (!gst_context_is_persistent (context)) {
2891 gst_context_unref (context);
2893 element->contexts = g_list_delete_link (element->contexts, l);
2899 GST_OBJECT_UNLOCK (element);
2903 /* this will catch real but unhandled state changes;
2904 * can only be caused by:
2905 * - a new state was added
2906 * - somehow the element was asked to jump across an intermediate state
2908 g_warning ("Unhandled state change from %s to %s",
2909 gst_element_state_get_name (state),
2910 gst_element_state_get_name (next));
2917 GST_OBJECT_LOCK (element);
2918 result = GST_STATE_RETURN (element);
2919 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2920 "element is already in the %s state",
2921 gst_element_state_get_name (state));
2922 GST_OBJECT_UNLOCK (element);
2929 * gst_element_get_factory:
2930 * @element: a #GstElement to request the element factory of.
2932 * Retrieves the factory that was used to create this element.
2934 * Returns: (transfer none): the #GstElementFactory used for creating this
2935 * element. no refcounting is needed.
2938 gst_element_get_factory (GstElement * element)
2940 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2942 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2946 gst_element_dispose (GObject * object)
2948 GstElement *element = GST_ELEMENT_CAST (object);
2951 GstElementClass *oclass;
2954 oclass = GST_ELEMENT_GET_CLASS (element);
2956 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "%p dispose", element);
2958 if (GST_STATE (element) != GST_STATE_NULL)
2961 /* start by releasing all request pads, this might also remove some dynamic
2963 walk = element->pads;
2965 GstPad *pad = GST_PAD_CAST (walk->data);
2969 if (oclass->release_pad && GST_PAD_PAD_TEMPLATE (pad) &&
2970 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
2971 == GST_PAD_REQUEST) {
2972 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2973 "removing request pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2974 oclass->release_pad (element, pad);
2976 /* in case the release_pad function removed the next pad too */
2977 if (walk && g_list_position (element->pads, walk) == -1)
2978 walk = element->pads;
2981 /* remove the remaining pads */
2982 while (element->pads) {
2983 GstPad *pad = GST_PAD_CAST (element->pads->data);
2984 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2985 "removing pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2986 if (!gst_element_remove_pad (element, pad)) {
2987 /* only happens when someone unparented our pad.. */
2988 g_critical ("failed to remove pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2993 GST_OBJECT_LOCK (element);
2994 clock_p = &element->clock;
2995 bus_p = &element->bus;
2996 gst_object_replace ((GstObject **) clock_p, NULL);
2997 gst_object_replace ((GstObject **) bus_p, NULL);
2998 g_list_free_full (element->contexts, (GDestroyNotify) gst_context_unref);
2999 GST_OBJECT_UNLOCK (element);
3001 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "%p parent class dispose",
3004 G_OBJECT_CLASS (parent_class)->dispose (object);
3013 is_locked = GST_ELEMENT_IS_LOCKED_STATE (element);
3015 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
3017 "You need to explicitly set elements to the NULL state before\n"
3018 "dropping the final reference, to allow them to clean up.\n"
3019 "This problem may also be caused by a refcounting bug in the\n"
3020 "application or some element.\n",
3021 GST_OBJECT_NAME (element),
3022 gst_element_state_get_name (GST_STATE (element)),
3023 is_locked ? " (locked)" : "");
3029 gst_element_finalize (GObject * object)
3031 GstElement *element = GST_ELEMENT_CAST (object);
3033 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "%p finalize", element);
3035 g_cond_clear (&element->state_cond);
3036 g_rec_mutex_clear (&element->state_lock);
3038 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "%p finalize parent",
3041 G_OBJECT_CLASS (parent_class)->finalize (object);
3045 gst_element_set_bus_func (GstElement * element, GstBus * bus)
3049 g_return_if_fail (GST_IS_ELEMENT (element));
3051 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
3053 GST_OBJECT_LOCK (element);
3054 bus_p = &GST_ELEMENT_BUS (element);
3055 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
3056 GST_OBJECT_UNLOCK (element);
3060 * gst_element_set_bus:
3061 * @element: a #GstElement to set the bus of.
3062 * @bus: (transfer none): the #GstBus to set.
3064 * Sets the bus of the element. Increases the refcount on the bus.
3065 * For internal use only, unless you're testing elements.
3070 gst_element_set_bus (GstElement * element, GstBus * bus)
3072 GstElementClass *oclass;
3074 g_return_if_fail (GST_IS_ELEMENT (element));
3076 oclass = GST_ELEMENT_GET_CLASS (element);
3078 if (oclass->set_bus)
3079 oclass->set_bus (element, bus);
3083 * gst_element_get_bus:
3084 * @element: a #GstElement to get the bus of.
3086 * Returns the bus of the element. Note that only a #GstPipeline will provide a
3087 * bus for the application.
3089 * Returns: (transfer full): the element's #GstBus. unref after usage.
3094 gst_element_get_bus (GstElement * element)
3096 GstBus *result = NULL;
3098 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3100 GST_OBJECT_LOCK (element);
3101 if ((result = GST_ELEMENT_BUS (element)))
3102 gst_object_ref (result);
3103 GST_OBJECT_UNLOCK (element);
3105 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,
3112 gst_element_set_context_default (GstElement * element, GstContext * context)
3114 const gchar *context_type;
3117 GST_OBJECT_LOCK (element);
3118 context_type = gst_context_get_context_type (context);
3119 for (l = element->contexts; l; l = l->next) {
3120 GstContext *tmp = l->data;
3121 const gchar *tmp_type = gst_context_get_context_type (tmp);
3123 /* Always store newest context but never replace
3124 * a persistent one by a non-persistent one */
3125 if (strcmp (context_type, tmp_type) == 0 &&
3126 (gst_context_is_persistent (context) ||
3127 !gst_context_is_persistent (tmp))) {
3128 gst_context_replace ((GstContext **) & l->data, context);
3132 /* Not found? Add */
3135 g_list_prepend (element->contexts, gst_context_ref (context));
3137 GST_OBJECT_UNLOCK (element);
3141 * gst_element_set_context:
3142 * @element: a #GstElement to set the context of.
3143 * @context: (transfer none): the #GstContext to set.
3145 * Sets the context of the element. Increases the refcount of the context.
3150 gst_element_set_context (GstElement * element, GstContext * context)
3152 GstElementClass *oclass;
3154 g_return_if_fail (GST_IS_ELEMENT (element));
3156 oclass = GST_ELEMENT_GET_CLASS (element);
3158 GST_CAT_DEBUG_OBJECT (GST_CAT_CONTEXT, element,
3159 "set context %p %" GST_PTR_FORMAT, context,
3160 gst_context_get_structure (context));
3162 if (oclass->set_context)
3163 oclass->set_context (element, context);
3167 * gst_element_get_contexts:
3168 * @element: a #GstElement to set the context of.
3170 * Gets the contexts set on the element.
3174 * Returns: (element-type Gst.Context) (transfer full): List of #GstContext
3179 gst_element_get_contexts (GstElement * element)
3183 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
3185 GST_OBJECT_LOCK (element);
3186 ret = g_list_copy_deep (element->contexts, (GCopyFunc) gst_context_ref, NULL);
3187 GST_OBJECT_UNLOCK (element);
3193 _match_context_type (GstContext * c1, const gchar * context_type)
3195 const gchar *c1_type;
3197 c1_type = gst_context_get_context_type (c1);
3199 return g_strcmp0 (c1_type, context_type);
3203 * gst_element_get_context_unlocked:
3204 * @element: a #GstElement to get the context of.
3205 * @context_type: a name of a context to retrieve
3207 * Gets the context with @context_type set on the element or NULL.
3209 * Returns: (transfer full): A #GstContext or NULL
3214 gst_element_get_context_unlocked (GstElement * element,
3215 const gchar * context_type)
3217 GstContext *ret = NULL;
3220 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
3223 g_list_find_custom (element->contexts, context_type,
3224 (GCompareFunc) _match_context_type);
3225 if (node && node->data)
3226 ret = gst_context_ref (node->data);
3232 * gst_element_get_context:
3233 * @element: a #GstElement to get the context of.
3234 * @context_type: a name of a context to retrieve
3236 * Gets the context with @context_type set on the element or NULL.
3240 * Returns: (transfer full): A #GstContext or NULL
3245 gst_element_get_context (GstElement * element, const gchar * context_type)
3247 GstContext *ret = NULL;
3249 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
3251 GST_OBJECT_LOCK (element);
3252 ret = gst_element_get_context_unlocked (element, context_type);
3253 GST_OBJECT_UNLOCK (element);
3259 gst_element_property_post_notify_msg (GstElement * element, GObject * obj,
3260 GParamSpec * pspec, gboolean include_value)
3262 GValue val = G_VALUE_INIT;
3265 GST_LOG_OBJECT (element, "property '%s' of object %" GST_PTR_FORMAT " has "
3266 "changed, posting message with%s value", pspec->name, obj,
3267 include_value ? "" : "out");
3269 if (include_value && (pspec->flags & G_PARAM_READABLE) != 0) {
3270 g_value_init (&val, pspec->value_type);
3271 g_object_get_property (obj, pspec->name, &val);
3276 gst_element_post_message (element,
3277 gst_message_new_property_notify (GST_OBJECT_CAST (obj), pspec->name, v));
3281 gst_element_property_deep_notify_cb (GstElement * element, GObject * prop_obj,
3282 GParamSpec * pspec, gpointer user_data)
3284 gboolean include_value = GPOINTER_TO_INT (user_data);
3286 gst_element_property_post_notify_msg (element, prop_obj, pspec,
3291 gst_element_property_notify_cb (GObject * obj, GParamSpec * pspec,
3294 gboolean include_value = GPOINTER_TO_INT (user_data);
3296 gst_element_property_post_notify_msg (GST_ELEMENT_CAST (obj), obj, pspec,
3301 * gst_element_add_property_notify_watch:
3302 * @element: a #GstElement to watch for property changes
3303 * @property_name: (allow-none): name of property to watch for changes, or
3304 * NULL to watch all properties
3305 * @include_value: whether to include the new property value in the message
3307 * Returns: a watch id, which can be used in connection with
3308 * gst_element_remove_property_notify_watch() to remove the watch again.
3313 gst_element_add_property_notify_watch (GstElement * element,
3314 const gchar * property_name, gboolean include_value)
3320 g_return_val_if_fail (GST_IS_ELEMENT (element), 0);
3322 sep = (property_name != NULL) ? "::" : NULL;
3323 signal_name = g_strconcat ("notify", sep, property_name, NULL);
3324 id = g_signal_connect (element, signal_name,
3325 G_CALLBACK (gst_element_property_notify_cb),
3326 GINT_TO_POINTER (include_value));
3327 g_free (signal_name);
3333 * gst_element_add_property_deep_notify_watch:
3334 * @element: a #GstElement to watch (recursively) for property changes
3335 * @property_name: (allow-none): name of property to watch for changes, or
3336 * NULL to watch all properties
3337 * @include_value: whether to include the new property value in the message
3339 * Returns: a watch id, which can be used in connection with
3340 * gst_element_remove_property_notify_watch() to remove the watch again.
3345 gst_element_add_property_deep_notify_watch (GstElement * element,
3346 const gchar * property_name, gboolean include_value)
3352 g_return_val_if_fail (GST_IS_ELEMENT (element), 0);
3354 sep = (property_name != NULL) ? "::" : NULL;
3355 signal_name = g_strconcat ("deep-notify", sep, property_name, NULL);
3356 id = g_signal_connect (element, signal_name,
3357 G_CALLBACK (gst_element_property_deep_notify_cb),
3358 GINT_TO_POINTER (include_value));
3359 g_free (signal_name);
3365 * gst_element_remove_property_notify_watch:
3366 * @element: a #GstElement being watched for property changes
3367 * @watch_id: watch id to remove
3372 gst_element_remove_property_notify_watch (GstElement * element, gulong watch_id)
3374 g_signal_handler_disconnect (element, watch_id);
3379 GstElement *element;
3380 GstElementCallAsyncFunc func;
3382 GDestroyNotify destroy_notify;
3383 } GstElementCallAsyncData;
3386 gst_element_call_async_func (gpointer data, gpointer user_data)
3388 GstElementCallAsyncData *async_data = data;
3390 async_data->func (async_data->element, async_data->user_data);
3391 if (async_data->destroy_notify)
3392 async_data->destroy_notify (async_data->user_data);
3393 gst_object_unref (async_data->element);
3394 g_free (async_data);
3398 * gst_element_call_async:
3399 * @element: a #GstElement
3400 * @func: Function to call asynchronously from another thread
3401 * @user_data: Data to pass to @func
3402 * @destroy_notify: GDestroyNotify for @user_data
3404 * Calls @func from another thread and passes @user_data to it. This is to be
3405 * used for cases when a state change has to be performed from a streaming
3406 * thread, directly via gst_element_set_state() or indirectly e.g. via SEEK
3409 * Calling those functions directly from the streaming thread will cause
3410 * deadlocks in many situations, as they might involve waiting for the
3411 * streaming thread to shut down from this very streaming thread.
3418 gst_element_call_async (GstElement * element, GstElementCallAsyncFunc func,
3419 gpointer user_data, GDestroyNotify destroy_notify)
3421 GstElementCallAsyncData *async_data;
3423 g_return_if_fail (GST_IS_ELEMENT (element));
3425 async_data = g_new0 (GstElementCallAsyncData, 1);
3426 async_data->element = gst_object_ref (element);
3427 async_data->func = func;
3428 async_data->user_data = user_data;
3429 async_data->destroy_notify = destroy_notify;
3431 g_thread_pool_push (gst_element_pool, async_data, NULL);
3435 _priv_gst_element_cleanup (void)
3437 if (gst_element_pool) {
3438 g_thread_pool_free (gst_element_pool, FALSE, TRUE);
3439 gst_element_setup_thread_pool ();