2 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
3 * 2004 Wim Taymans <wim@fluendo.com>
5 * gstelement.c: The base element, all elements derive from this
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Library General Public
9 * License as published by the Free Software Foundation; either
10 * version 2 of the License, or (at your option) any later version.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Library General Public License for more details.
17 * You should have received a copy of the GNU Library General Public
18 * License along with this library; if not, write to the
19 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 * Boston, MA 02111-1307, USA.
25 * @short_description: Abstract base class for all pipeline elements
26 * @see_also: #GstElementFactory, #GstPad
28 * GstElement is the abstract base class needed to construct an element that
29 * can be used in a GStreamer pipeline. Please refer to the plugin writers
30 * guide for more information on creating #GstElement subclasses.
32 * The name of a #GstElement can be get with gst_element_get_name() and set with
33 * gst_element_set_name(). For speed, GST_ELEMENT_NAME() can be used in the
34 * core when using the appropriate locking. Do not use this in plug-ins or
35 * applications in order to retain ABI compatibility.
37 * All elements have pads (of the type #GstPad). These pads link to pads on
38 * other elements. #GstBuffer flow between these linked pads.
39 * A #GstElement has a #GList of #GstPad structures for all their input (or sink)
40 * and output (or source) pads.
41 * Core and plug-in writers can add and remove pads with gst_element_add_pad()
42 * and gst_element_remove_pad().
44 * A pad of an element can be retrieved by name with gst_element_get_pad().
45 * An iterator of all pads can be retrieved with gst_element_iterate_pads().
47 * Elements can be linked through their pads.
48 * If the link is straightforward, use the gst_element_link()
49 * convenience function to link two elements, or gst_element_link_many()
50 * for more elements in a row.
51 * Use gst_element_link_filtered() to link two elements constrained by
52 * a specified set of #GstCaps.
53 * For finer control, use gst_element_link_pads() and
54 * gst_element_link_pads_filtered() to specify the pads to link on
55 * each element by name.
57 * Each element has a state (see #GstState). You can get and set the state
58 * of an element with gst_element_get_state() and gst_element_set_state().
59 * Setting a state triggers a #GstStateChange. To get a string representation
60 * of a #GstState, use gst_element_state_get_name().
62 * You can get and set a #GstClock on an element using gst_element_get_clock()
63 * and gst_element_set_clock().
64 * Some elements can provide a clock for the pipeline if
65 * gst_element_provides_clock() returns %TRUE. With the
66 * gst_element_provide_clock() method one can retrieve the clock provided by
68 * Not all elements require a clock to operate correctly. If
69 * gst_element_requires_clock() returns %TRUE, a clock should be set on the
70 * element with gst_element_set_clock().
72 * Note that clock slection and distribution is normally handled by the
73 * toplevel #GstPipeline so the clock functions are only to be used in very
74 * specific situations.
76 * Last reviewed on 2009-05-29 (0.10.24)
79 #include "gst_private.h"
82 #include <gobject/gvaluecollector.h>
84 #include "gstelement.h"
85 #include "gstelementmetadata.h"
86 #include "gstenumtypes.h"
88 #include "gstmarshal.h"
94 #include "gst-i18n-lib.h"
96 /* Element signals and args */
112 static void gst_element_class_init (GstElementClass * klass);
113 static void gst_element_init (GstElement * element);
114 static void gst_element_base_class_init (gpointer g_class);
115 static void gst_element_base_class_finalize (gpointer g_class);
117 static void gst_element_dispose (GObject * object);
118 static void gst_element_finalize (GObject * object);
120 static GstStateChangeReturn gst_element_change_state_func (GstElement * element,
121 GstStateChange transition);
122 static GstStateChangeReturn gst_element_get_state_func (GstElement * element,
123 GstState * state, GstState * pending, GstClockTime timeout);
124 static GstStateChangeReturn gst_element_set_state_func (GstElement * element,
126 static void gst_element_set_bus_func (GstElement * element, GstBus * bus);
128 static gboolean gst_element_default_send_event (GstElement * element,
130 static gboolean gst_element_default_query (GstElement * element,
133 static GstPadTemplate
134 * gst_element_class_get_request_pad_template (GstElementClass *
135 element_class, const gchar * name);
137 static GstObjectClass *parent_class = NULL;
138 static guint gst_element_signals[LAST_SIGNAL] = { 0 };
140 /* this is used in gstelementfactory.c:gst_element_register() */
141 GQuark _gst_elementclass_factory = 0;
144 gst_element_get_type (void)
146 static volatile gsize gst_element_type = 0;
148 if (g_once_init_enter (&gst_element_type)) {
150 static const GTypeInfo element_info = {
151 sizeof (GstElementClass),
152 gst_element_base_class_init,
153 gst_element_base_class_finalize,
154 (GClassInitFunc) gst_element_class_init,
159 (GInstanceInitFunc) gst_element_init,
163 _type = g_type_register_static (GST_TYPE_OBJECT, "GstElement",
164 &element_info, G_TYPE_FLAG_ABSTRACT);
166 _gst_elementclass_factory =
167 g_quark_from_static_string ("GST_ELEMENTCLASS_FACTORY");
168 g_once_init_leave (&gst_element_type, _type);
170 return gst_element_type;
174 gst_element_class_init (GstElementClass * klass)
176 GObjectClass *gobject_class;
177 GstObjectClass *gstobject_class;
179 gobject_class = (GObjectClass *) klass;
180 gstobject_class = (GstObjectClass *) klass;
182 parent_class = g_type_class_peek_parent (klass);
185 * GstElement::pad-added:
186 * @gstelement: the object which received the signal
187 * @new_pad: the pad that has been added
189 * a new #GstPad has been added to the element. Note that this signal will
190 * usually be emitted from the context of the streaming thread. Also keep in
191 * mind that if you add new elements to the pipeline in the signal handler
192 * you will need to set them to the desired target state with
193 * gst_element_set_state() or gst_element_sync_state_with_parent().
195 gst_element_signals[PAD_ADDED] =
196 g_signal_new ("pad-added", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
197 G_STRUCT_OFFSET (GstElementClass, pad_added), NULL, NULL,
198 gst_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GST_TYPE_PAD);
200 * GstElement::pad-removed:
201 * @gstelement: the object which received the signal
202 * @old_pad: the pad that has been removed
204 * a #GstPad has been removed from the element
206 gst_element_signals[PAD_REMOVED] =
207 g_signal_new ("pad-removed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
208 G_STRUCT_OFFSET (GstElementClass, pad_removed), NULL, NULL,
209 gst_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GST_TYPE_PAD);
211 * GstElement::no-more-pads:
212 * @gstelement: the object which received the signal
214 * This signals that the element will not generate more dynamic pads.
215 * Note that this signal will usually be emitted from the context of
216 * the streaming thread.
218 gst_element_signals[NO_MORE_PADS] =
219 g_signal_new ("no-more-pads", G_TYPE_FROM_CLASS (klass),
220 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstElementClass, no_more_pads), NULL,
221 NULL, gst_marshal_VOID__VOID, G_TYPE_NONE, 0);
223 gobject_class->dispose = gst_element_dispose;
224 gobject_class->finalize = gst_element_finalize;
226 klass->change_state = GST_DEBUG_FUNCPTR (gst_element_change_state_func);
227 klass->set_state = GST_DEBUG_FUNCPTR (gst_element_set_state_func);
228 klass->get_state = GST_DEBUG_FUNCPTR (gst_element_get_state_func);
229 klass->set_bus = GST_DEBUG_FUNCPTR (gst_element_set_bus_func);
230 klass->query = GST_DEBUG_FUNCPTR (gst_element_default_query);
231 klass->send_event = GST_DEBUG_FUNCPTR (gst_element_default_send_event);
232 klass->numpadtemplates = 0;
234 klass->elementfactory = NULL;
238 gst_element_base_class_init (gpointer g_class)
240 GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
241 GList *node, *padtemplates;
243 /* Copy the element details here so elements can inherit the
244 * details from their base class and classes only need to set
245 * the details in class_init instead of base_init */
246 element_class->metadata =
247 element_class->metadata ? gst_structure_copy (element_class->metadata) :
248 gst_structure_empty_new ("metadata");
250 /* Copy the pad templates so elements inherit them
251 * from their base class but elements can add pad templates in class_init
252 * instead of base_init.
254 padtemplates = g_list_copy (element_class->padtemplates);
255 for (node = padtemplates; node != NULL; node = node->next) {
256 GstPadTemplate *tmpl = (GstPadTemplate *) node->data;
257 gst_object_ref (tmpl);
259 element_class->padtemplates = padtemplates;
261 /* set the factory, see gst_element_register() */
262 element_class->elementfactory =
263 g_type_get_qdata (G_TYPE_FROM_CLASS (element_class),
264 _gst_elementclass_factory);
265 GST_DEBUG ("type %s : factory %p", G_OBJECT_CLASS_NAME (element_class),
266 element_class->elementfactory);
270 gst_element_base_class_finalize (gpointer g_class)
272 GstElementClass *klass = GST_ELEMENT_CLASS (g_class);
274 g_list_foreach (klass->padtemplates, (GFunc) gst_object_unref, NULL);
275 g_list_free (klass->padtemplates);
277 gst_structure_free (klass->metadata);
281 gst_element_init (GstElement * element)
283 GST_STATE (element) = GST_STATE_NULL;
284 GST_STATE_TARGET (element) = GST_STATE_NULL;
285 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
286 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
287 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
289 /* FIXME 0.11: Store this directly in the instance struct */
290 element->state_lock = g_slice_new (GStaticRecMutex);
291 g_static_rec_mutex_init (element->state_lock);
292 element->state_cond = g_cond_new ();
296 * gst_element_release_request_pad:
297 * @element: a #GstElement to release the request pad of.
298 * @pad: the #GstPad to release.
300 * Makes the element free the previously requested pad as obtained
301 * with gst_element_get_request_pad().
303 * This does not unref the pad. If the pad was created by using
304 * gst_element_get_request_pad(), gst_element_release_request_pad() needs to be
305 * followed by gst_object_unref() to free the @pad.
310 gst_element_release_request_pad (GstElement * element, GstPad * pad)
312 GstElementClass *oclass;
314 g_return_if_fail (GST_IS_ELEMENT (element));
315 g_return_if_fail (GST_IS_PAD (pad));
317 oclass = GST_ELEMENT_GET_CLASS (element);
319 /* if the element implements a custom release function we call that, else we
320 * simply remove the pad from the element */
321 if (oclass->release_pad)
322 (oclass->release_pad) (element, pad);
324 gst_element_remove_pad (element, pad);
328 * gst_element_requires_clock:
329 * @element: a #GstElement to query
331 * Query if the element requires a clock.
333 * Returns: %TRUE if the element requires a clock
338 gst_element_requires_clock (GstElement * element)
342 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
344 result = (GST_ELEMENT_GET_CLASS (element)->set_clock != NULL);
350 * gst_element_provides_clock:
351 * @element: a #GstElement to query
353 * Query if the element provides a clock. A #GstClock provided by an
354 * element can be used as the global #GstClock for the pipeline.
355 * An element that can provide a clock is only required to do so in the PAUSED
356 * state, this means when it is fully negotiated and has allocated the resources
357 * to operate the clock.
359 * Returns: %TRUE if the element provides a clock
364 gst_element_provides_clock (GstElement * element)
368 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
370 result = (GST_ELEMENT_GET_CLASS (element)->provide_clock != NULL);
376 * gst_element_provide_clock:
377 * @element: a #GstElement to query
379 * Get the clock provided by the given element.
380 * <note>An element is only required to provide a clock in the PAUSED
381 * state. Some elements can provide a clock in other states.</note>
383 * Returns: (transfer full): the GstClock provided by the element or %NULL
384 * if no clock could be provided. Unref after usage.
389 gst_element_provide_clock (GstElement * element)
391 GstClock *result = NULL;
392 GstElementClass *oclass;
394 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
396 oclass = GST_ELEMENT_GET_CLASS (element);
398 if (oclass->provide_clock)
399 result = oclass->provide_clock (element);
405 * gst_element_set_clock:
406 * @element: a #GstElement to set the clock for.
407 * @clock: the #GstClock to set for the element.
409 * Sets the clock for the element. This function increases the
410 * refcount on the clock. Any previously set clock on the object
413 * Returns: %TRUE if the element accepted the clock. An element can refuse a
414 * clock when it, for example, is not able to slave its internal clock to the
415 * @clock or when it requires a specific clock to operate.
420 gst_element_set_clock (GstElement * element, GstClock * clock)
422 GstElementClass *oclass;
426 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
427 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
429 oclass = GST_ELEMENT_GET_CLASS (element);
431 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
433 if (oclass->set_clock)
434 res = oclass->set_clock (element, clock);
437 /* only update the clock pointer if the element accepted the clock */
438 GST_OBJECT_LOCK (element);
439 clock_p = &element->clock;
440 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
441 GST_OBJECT_UNLOCK (element);
447 * gst_element_get_clock:
448 * @element: a #GstElement to get the clock of.
450 * Gets the currently configured clock of the element. This is the clock as was
451 * last set with gst_element_set_clock().
453 * Returns: (transfer full): the #GstClock of the element. unref after usage.
458 gst_element_get_clock (GstElement * element)
462 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
464 GST_OBJECT_LOCK (element);
465 if ((result = element->clock))
466 gst_object_ref (result);
467 GST_OBJECT_UNLOCK (element);
473 * gst_element_set_base_time:
474 * @element: a #GstElement.
475 * @time: the base time to set.
477 * Set the base time of an element. See gst_element_get_base_time().
482 gst_element_set_base_time (GstElement * element, GstClockTime time)
486 g_return_if_fail (GST_IS_ELEMENT (element));
488 GST_OBJECT_LOCK (element);
489 old = element->base_time;
490 element->base_time = time;
491 GST_OBJECT_UNLOCK (element);
493 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
494 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
495 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
499 * gst_element_get_base_time:
500 * @element: a #GstElement.
502 * Returns the base time of the element. The base time is the
503 * absolute time of the clock when this element was last put to
504 * PLAYING. Subtracting the base time from the clock time gives
505 * the running time of the element.
507 * Returns: the base time of the element.
512 gst_element_get_base_time (GstElement * element)
516 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
518 GST_OBJECT_LOCK (element);
519 result = element->base_time;
520 GST_OBJECT_UNLOCK (element);
526 * gst_element_set_start_time:
527 * @element: a #GstElement.
528 * @time: the base time to set.
530 * Set the start time of an element. The start time of the element is the
531 * running time of the element when it last went to the PAUSED state. In READY
532 * or after a flushing seek, it is set to 0.
534 * Toplevel elements like #GstPipeline will manage the start_time and
535 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
536 * on such a toplevel element will disable the distribution of the base_time to
537 * the children and can be useful if the application manages the base_time
538 * itself, for example if you want to synchronize capture from multiple
539 * pipelines, and you can also ensure that the pipelines have the same clock.
546 gst_element_set_start_time (GstElement * element, GstClockTime time)
550 g_return_if_fail (GST_IS_ELEMENT (element));
552 GST_OBJECT_LOCK (element);
553 old = GST_ELEMENT_START_TIME (element);
554 GST_ELEMENT_START_TIME (element) = time;
555 GST_OBJECT_UNLOCK (element);
557 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
558 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
559 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
563 * gst_element_get_start_time:
564 * @element: a #GstElement.
566 * Returns the start time of the element. The start time is the
567 * running time of the clock when this element was last put to PAUSED.
569 * Usually the start_time is managed by a toplevel element such as
574 * Returns: the start time of the element.
579 gst_element_get_start_time (GstElement * element)
583 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
585 GST_OBJECT_LOCK (element);
586 result = GST_ELEMENT_START_TIME (element);
587 GST_OBJECT_UNLOCK (element);
593 * gst_element_is_indexable:
594 * @element: a #GstElement.
596 * Queries if the element can be indexed.
598 * Returns: TRUE if the element can be indexed.
603 gst_element_is_indexable (GstElement * element)
607 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
609 result = (GST_ELEMENT_GET_CLASS (element)->set_index != NULL);
615 * gst_element_set_index:
616 * @element: a #GstElement.
617 * @index: (transfer none): a #GstIndex.
619 * Set @index on the element. The refcount of the index
620 * will be increased, any previously set index is unreffed.
625 gst_element_set_index (GstElement * element, GstIndex * index)
627 GstElementClass *oclass;
629 g_return_if_fail (GST_IS_ELEMENT (element));
630 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
632 oclass = GST_ELEMENT_GET_CLASS (element);
634 if (oclass->set_index)
635 oclass->set_index (element, index);
639 * gst_element_get_index:
640 * @element: a #GstElement.
642 * Gets the index from the element.
644 * Returns: (transfer full): a #GstIndex or %NULL when no index was set on the
645 * element. unref after usage.
650 gst_element_get_index (GstElement * element)
652 GstElementClass *oclass;
653 GstIndex *result = NULL;
655 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
657 oclass = GST_ELEMENT_GET_CLASS (element);
659 if (oclass->get_index)
660 result = oclass->get_index (element);
666 * gst_element_add_pad:
667 * @element: a #GstElement to add the pad to.
668 * @pad: (transfer full): the #GstPad to add to the element.
670 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
671 * see gst_object_set_parent() for refcounting information.
673 * Pads are not automatically activated so elements should perform the needed
674 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
675 * state. See gst_pad_set_active() for more information about activating pads.
677 * The pad and the element should be unlocked when calling this function.
679 * This function will emit the #GstElement::pad-added signal on the element.
681 * Returns: %TRUE if the pad could be added. This function can fail when
682 * a pad with the same name already existed or the pad already had another
688 gst_element_add_pad (GstElement * element, GstPad * pad)
693 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
694 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
696 /* locking pad to look at the name */
697 GST_OBJECT_LOCK (pad);
698 pad_name = g_strdup (GST_PAD_NAME (pad));
699 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
700 GST_STR_NULL (pad_name));
701 flushing = GST_PAD_IS_FLUSHING (pad);
702 GST_OBJECT_UNLOCK (pad);
704 /* then check to see if there's already a pad by that name here */
705 GST_OBJECT_LOCK (element);
706 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
709 /* try to set the pad's parent */
710 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
711 GST_OBJECT_CAST (element))))
714 /* check for flushing pads */
715 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
716 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
717 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
718 "use gst_pad_set_active(pad,TRUE) before adding it.",
719 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
721 GST_OBJECT_LOCK (pad);
722 GST_PAD_UNSET_FLUSHING (pad);
723 GST_OBJECT_UNLOCK (pad);
728 /* add it to the list */
729 switch (gst_pad_get_direction (pad)) {
731 element->srcpads = g_list_prepend (element->srcpads, pad);
732 element->numsrcpads++;
735 element->sinkpads = g_list_prepend (element->sinkpads, pad);
736 element->numsinkpads++;
741 element->pads = g_list_prepend (element->pads, pad);
743 element->pads_cookie++;
744 GST_OBJECT_UNLOCK (element);
746 /* emit the PAD_ADDED signal */
747 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
754 g_critical ("Padname %s is not unique in element %s, not adding",
755 pad_name, GST_ELEMENT_NAME (element));
756 GST_OBJECT_UNLOCK (element);
763 ("Pad %s already has parent when trying to add to element %s",
764 pad_name, GST_ELEMENT_NAME (element));
765 GST_OBJECT_UNLOCK (element);
771 GST_OBJECT_LOCK (pad);
773 ("Trying to add pad %s to element %s, but it has no direction",
774 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
775 GST_OBJECT_UNLOCK (pad);
776 GST_OBJECT_UNLOCK (element);
782 * gst_element_remove_pad:
783 * @element: a #GstElement to remove pad from.
784 * @pad: (transfer none): the #GstPad to remove from the element.
786 * Removes @pad from @element. @pad will be destroyed if it has not been
787 * referenced elsewhere using gst_object_unparent().
789 * This function is used by plugin developers and should not be used
790 * by applications. Pads that were dynamically requested from elements
791 * with gst_element_get_request_pad() should be released with the
792 * gst_element_release_request_pad() function instead.
794 * Pads are not automatically deactivated so elements should perform the needed
795 * steps to deactivate the pad in case this pad is removed in the PAUSED or
796 * PLAYING state. See gst_pad_set_active() for more information about
799 * The pad and the element should be unlocked when calling this function.
801 * This function will emit the #GstElement::pad-removed signal on the element.
803 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
804 * pad does not belong to the provided element.
809 gst_element_remove_pad (GstElement * element, GstPad * pad)
813 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
814 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
816 /* locking pad to look at the name and parent */
817 GST_OBJECT_LOCK (pad);
818 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
819 GST_STR_NULL (GST_PAD_NAME (pad)));
821 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
823 GST_OBJECT_UNLOCK (pad);
826 if ((peer = gst_pad_get_peer (pad))) {
827 /* window for MT unsafeness, someone else could unlink here
828 * and then we call unlink with wrong pads. The unlink
829 * function would catch this and safely return failed. */
830 if (GST_PAD_IS_SRC (pad))
831 gst_pad_unlink (pad, peer);
833 gst_pad_unlink (peer, pad);
835 gst_object_unref (peer);
838 GST_OBJECT_LOCK (element);
839 /* remove it from the list */
840 switch (gst_pad_get_direction (pad)) {
842 element->srcpads = g_list_remove (element->srcpads, pad);
843 element->numsrcpads--;
846 element->sinkpads = g_list_remove (element->sinkpads, pad);
847 element->numsinkpads--;
850 g_critical ("Removing pad without direction???");
853 element->pads = g_list_remove (element->pads, pad);
855 element->pads_cookie++;
856 GST_OBJECT_UNLOCK (element);
858 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
859 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
861 gst_object_unparent (GST_OBJECT_CAST (pad));
868 /* FIXME, locking order? */
869 GST_OBJECT_LOCK (element);
870 g_critical ("Padname %s:%s does not belong to element %s when removing",
871 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
872 GST_OBJECT_UNLOCK (element);
873 GST_OBJECT_UNLOCK (pad);
879 * gst_element_no_more_pads:
880 * @element: a #GstElement
882 * Use this function to signal that the element does not expect any more pads
883 * to show up in the current pipeline. This function should be called whenever
884 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
885 * pad templates use this in combination with autopluggers to figure out that
886 * the element is done initializing its pads.
888 * This function emits the #GstElement::no-more-pads signal.
893 gst_element_no_more_pads (GstElement * element)
895 g_return_if_fail (GST_IS_ELEMENT (element));
897 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
901 pad_compare_name (GstPad * pad1, const gchar * name)
905 GST_OBJECT_LOCK (pad1);
906 result = strcmp (GST_PAD_NAME (pad1), name);
907 GST_OBJECT_UNLOCK (pad1);
913 * gst_element_get_static_pad:
914 * @element: a #GstElement to find a static pad of.
915 * @name: the name of the static #GstPad to retrieve.
917 * Retrieves a pad from @element by name. This version only retrieves
918 * already-existing (i.e. 'static') pads.
920 * Returns: (transfer full): the requested #GstPad if found, otherwise %NULL.
926 gst_element_get_static_pad (GstElement * element, const gchar * name)
929 GstPad *result = NULL;
931 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
932 g_return_val_if_fail (name != NULL, NULL);
934 GST_OBJECT_LOCK (element);
936 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
938 result = GST_PAD_CAST (find->data);
939 gst_object_ref (result);
942 if (result == NULL) {
943 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
944 name, GST_ELEMENT_NAME (element));
946 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
947 GST_ELEMENT_NAME (element), name);
949 GST_OBJECT_UNLOCK (element);
955 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
956 const gchar * name, const GstCaps * caps)
958 GstPad *newpad = NULL;
959 GstElementClass *oclass;
961 oclass = GST_ELEMENT_GET_CLASS (element);
963 #ifndef G_DISABLE_CHECKS
964 /* Some sanity checking here */
968 /* Is this the template name? */
969 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
970 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
972 const gchar *str, *data;
975 /* Otherwise check if it's a valid name for the name template */
976 str = strchr (templ->name_template, '%');
977 g_return_val_if_fail (str != NULL, NULL);
978 g_return_val_if_fail (strncmp (templ->name_template, name,
979 str - templ->name_template) == 0, NULL);
980 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
982 data = name + (str - templ->name_template);
984 /* Can either be %s or %d or %u, do sanity checking for %d */
985 if (*(str + 1) == 'd') {
989 tmp = g_ascii_strtoll (data, &endptr, 10);
990 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
991 && *endptr == '\0', NULL);
992 } else if (*(str + 1) == 'u') {
996 tmp = g_ascii_strtoull (data, &endptr, 10);
997 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
1001 pad = gst_element_get_static_pad (element, name);
1003 gst_object_unref (pad);
1004 /* FIXME 0.11: Change this to g_return_val_if_fail() */
1005 g_critical ("Element %s already has a pad named %s, the behaviour of "
1006 " gst_element_get_request_pad() for existing pads is undefined!",
1007 GST_ELEMENT_NAME (element), name);
1012 if (oclass->request_new_pad)
1013 newpad = (oclass->request_new_pad) (element, templ, name, caps);
1016 gst_object_ref (newpad);
1022 * gst_element_get_request_pad:
1023 * @element: a #GstElement to find a request pad of.
1024 * @name: the name of the request #GstPad to retrieve.
1026 * Retrieves a pad from the element by name. This version only retrieves
1027 * request pads. The pad should be released with
1028 * gst_element_release_request_pad().
1030 * This method is slow and will be deprecated in the future. New code should
1031 * use gst_element_request_pad() with the requested template.
1033 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1034 * Release after usage.
1037 gst_element_get_request_pad (GstElement * element, const gchar * name)
1039 GstPadTemplate *templ = NULL;
1041 const gchar *req_name = NULL;
1042 gboolean templ_found = FALSE;
1045 gchar *str, *endptr = NULL;
1046 GstElementClass *class;
1048 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1049 g_return_val_if_fail (name != NULL, NULL);
1051 class = GST_ELEMENT_GET_CLASS (element);
1053 /* if the name contains a %, we assume it's the complete template name. Get
1054 * the template and try to get a pad */
1055 if (strstr (name, "%")) {
1056 templ = gst_element_class_get_request_pad_template (class, name);
1061 /* there is no % in the name, try to find a matching template */
1062 list = class->padtemplates;
1063 while (!templ_found && list) {
1064 templ = (GstPadTemplate *) list->data;
1065 if (templ->presence == GST_PAD_REQUEST) {
1066 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1067 templ->name_template);
1068 /* see if we find an exact match */
1069 if (strcmp (name, templ->name_template) == 0) {
1074 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1075 and %d and %u, occurring at the end of the name_template, are the only
1077 else if ((str = strchr (templ->name_template, '%'))
1078 && strncmp (templ->name_template, name,
1079 str - templ->name_template) == 0
1080 && strlen (name) > str - templ->name_template) {
1081 data = name + (str - templ->name_template);
1082 if (*(str + 1) == 'd') {
1086 tmp = strtol (data, &endptr, 10);
1087 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1093 } else if (*(str + 1) == 'u') {
1097 tmp = strtoul (data, &endptr, 10);
1098 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1118 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1124 * gst_element_request_pad:
1125 * @element: a #GstElement to find a request pad of.
1126 * @templ: a #GstPadTemplate of which we want a pad of.
1127 * @name: (transfer none) (allow-none): the name of the request #GstPad
1128 * to retrieve. Can be %NULL.
1129 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1130 * request. Can be %NULL.
1132 * Retrieves a request pad from the element according to the provided template.
1134 * If the @caps are specified and the element implements thew new
1135 * request_new_pad_full virtual method, the element will use them to select
1136 * which pad to create.
1138 * The pad should be released with gst_element_release_request_pad().
1140 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1141 * Release after usage.
1146 gst_element_request_pad (GstElement * element,
1147 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1149 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1150 g_return_val_if_fail (templ != NULL, NULL);
1152 return _gst_element_request_pad (element, templ, name, caps);
1156 * gst_element_get_pad:
1157 * @element: a #GstElement.
1158 * @name: the name of the pad to retrieve.
1160 * Retrieves a pad from @element by name. Tries gst_element_get_static_pad()
1161 * first, then gst_element_get_request_pad().
1163 * Deprecated: This function is deprecated as it's unclear if the reference
1164 * to the result pad should be released with gst_object_unref() in case of a static pad
1165 * or gst_element_release_request_pad() in case of a request pad.
1166 * Use gst_element_get_static_pad() or gst_element_get_request_pad() instead.
1168 * Returns: (transfer full): the #GstPad if found, otherwise %NULL. Unref or Release after usage,
1169 * depending on the type of the pad.
1171 #ifndef GST_REMOVE_DEPRECATED
1172 #ifdef GST_DISABLE_DEPRECATED
1173 GstPad *gst_element_get_pad (GstElement * element, const gchar * name);
1176 gst_element_get_pad (GstElement * element, const gchar * name)
1180 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1181 g_return_val_if_fail (name != NULL, NULL);
1183 pad = gst_element_get_static_pad (element, name);
1185 pad = gst_element_get_request_pad (element, name);
1189 #endif /* GST_REMOVE_DEPRECATED */
1191 static GstIterator *
1192 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1194 GstIterator *result;
1196 GST_OBJECT_LOCK (element);
1197 result = gst_iterator_new_list (GST_TYPE_PAD,
1198 GST_OBJECT_GET_LOCK (element),
1199 &element->pads_cookie, padlist, (GObject *) element, NULL);
1200 GST_OBJECT_UNLOCK (element);
1206 * gst_element_iterate_pads:
1207 * @element: a #GstElement to iterate pads of.
1209 * Retrieves an iterattor of @element's pads. The iterator should
1210 * be freed after usage.
1212 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1218 gst_element_iterate_pads (GstElement * element)
1220 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1222 return gst_element_iterate_pad_list (element, &element->pads);
1226 * gst_element_iterate_src_pads:
1227 * @element: a #GstElement.
1229 * Retrieves an iterator of @element's source pads.
1231 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1237 gst_element_iterate_src_pads (GstElement * element)
1239 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1241 return gst_element_iterate_pad_list (element, &element->srcpads);
1245 * gst_element_iterate_sink_pads:
1246 * @element: a #GstElement.
1248 * Retrieves an iterator of @element's sink pads.
1250 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1256 gst_element_iterate_sink_pads (GstElement * element)
1258 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1260 return gst_element_iterate_pad_list (element, &element->sinkpads);
1264 * gst_element_class_add_pad_template:
1265 * @klass: the #GstElementClass to add the pad template to.
1266 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1268 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1269 * functions of classes. If a pad template with the same name as an already
1270 * existing one is added the old one is replaced by the new one.
1274 gst_element_class_add_pad_template (GstElementClass * klass,
1275 GstPadTemplate * templ)
1277 GList *template_list = klass->padtemplates;
1279 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1280 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1282 /* If we already have a pad template with the same name replace the
1284 while (template_list) {
1285 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1287 /* Found pad with the same name, replace and return */
1288 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1289 gst_object_unref (padtempl);
1290 template_list->data = templ;
1293 template_list = g_list_next (template_list);
1296 /* Take ownership of the floating ref */
1297 g_object_ref_sink (templ);
1299 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1300 klass->numpadtemplates++;
1304 * gst_element_class_add_metadata:
1305 * @klass: class to set metadata for
1306 * @key: the key to set
1307 * @value: the value to set
1309 * Set @key with @value as metadata in @klass.
1312 gst_element_class_add_metadata (GstElementClass * klass,
1313 const gchar * key, const gchar * value)
1315 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1316 g_return_if_fail (key != NULL);
1317 g_return_if_fail (value != NULL);
1319 gst_structure_set ((GstStructure *) klass->metadata,
1320 key, G_TYPE_STRING, value, NULL);
1324 * gst_element_class_set_metadata:
1325 * @klass: class to set metadata for
1326 * @longname: The long English name of the element. E.g. "File Sink"
1327 * @classification: String describing the type of element, as an unordered list
1328 * separated with slashes ('/'). See draft-klass.txt of the design docs
1329 * for more details and common types. E.g: "Sink/File"
1330 * @description: Sentence describing the purpose of the element.
1331 * E.g: "Write stream to a file"
1332 * @author: Name and contact details of the author(s). Use \n to separate
1333 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1335 * Sets the detailed information for a #GstElementClass.
1336 * <note>This function is for use in _class_init functions only.</note>
1339 gst_element_class_set_metadata (GstElementClass * klass,
1340 const gchar * longname, const gchar * classification,
1341 const gchar * description, const gchar * author)
1343 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1345 gst_structure_set ((GstStructure *) klass->metadata,
1346 GST_ELEMENT_METADATA_LONGNAME, G_TYPE_STRING, longname,
1347 GST_ELEMENT_METADATA_KLASS, G_TYPE_STRING, classification,
1348 GST_ELEMENT_METADATA_DESCRIPTION, G_TYPE_STRING, description,
1349 GST_ELEMENT_METADATA_AUTHOR, G_TYPE_STRING, author, NULL);
1353 * gst_element_class_get_metadata:
1354 * @klass: class to get metadata for
1355 * @key: the key to get
1357 * Get metadata with @key in @klass.
1359 * Returns: the metadata for @key.
1361 G_CONST_RETURN gchar *
1362 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1364 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1365 g_return_val_if_fail (key != NULL, NULL);
1367 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1371 * gst_element_class_get_pad_template_list:
1372 * @element_class: a #GstElementClass to get pad templates of.
1374 * Retrieves a list of the pad templates associated with @element_class. The
1375 * list must not be modified by the calling code.
1376 * <note>If you use this function in the #GInstanceInitFunc of an object class
1377 * that has subclasses, make sure to pass the g_class parameter of the
1378 * #GInstanceInitFunc here.</note>
1380 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1384 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1386 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1388 return element_class->padtemplates;
1392 * gst_element_class_get_pad_template:
1393 * @element_class: a #GstElementClass to get the pad template of.
1394 * @name: the name of the #GstPadTemplate to get.
1396 * Retrieves a padtemplate from @element_class with the given name.
1397 * <note>If you use this function in the #GInstanceInitFunc of an object class
1398 * that has subclasses, make sure to pass the g_class parameter of the
1399 * #GInstanceInitFunc here.</note>
1401 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1402 * if none was found. No unreferencing is necessary.
1405 gst_element_class_get_pad_template (GstElementClass *
1406 element_class, const gchar * name)
1410 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1411 g_return_val_if_fail (name != NULL, NULL);
1413 padlist = element_class->padtemplates;
1416 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1418 if (strcmp (padtempl->name_template, name) == 0)
1421 padlist = g_list_next (padlist);
1427 static GstPadTemplate *
1428 gst_element_class_get_request_pad_template (GstElementClass *
1429 element_class, const gchar * name)
1431 GstPadTemplate *tmpl;
1433 tmpl = gst_element_class_get_pad_template (element_class, name);
1434 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1440 /* get a random pad on element of the given direction.
1441 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1444 gst_element_get_random_pad (GstElement * element,
1445 gboolean need_linked, GstPadDirection dir)
1447 GstPad *result = NULL;
1450 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1454 GST_OBJECT_LOCK (element);
1455 pads = element->srcpads;
1458 GST_OBJECT_LOCK (element);
1459 pads = element->sinkpads;
1462 goto wrong_direction;
1464 for (; pads; pads = g_list_next (pads)) {
1465 GstPad *pad = GST_PAD_CAST (pads->data);
1467 GST_OBJECT_LOCK (pad);
1468 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1469 GST_DEBUG_PAD_NAME (pad));
1471 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1472 /* if we require a linked pad, and it is not linked, continue the
1474 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1475 GST_DEBUG_PAD_NAME (pad));
1476 GST_OBJECT_UNLOCK (pad);
1479 /* found a pad, stop search */
1480 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1481 GST_DEBUG_PAD_NAME (pad));
1482 GST_OBJECT_UNLOCK (pad);
1488 gst_object_ref (result);
1490 GST_OBJECT_UNLOCK (element);
1494 /* ERROR handling */
1497 g_warning ("unknown pad direction %d", dir);
1503 gst_element_default_send_event (GstElement * element, GstEvent * event)
1505 gboolean result = FALSE;
1508 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1509 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1510 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1513 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1514 "pushing %s event to random %s pad %s:%s",
1515 GST_EVENT_TYPE_NAME (event),
1516 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1517 GST_DEBUG_PAD_NAME (pad));
1519 result = gst_pad_push_event (pad, event);
1520 gst_object_unref (pad);
1522 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1523 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1524 gst_event_unref (event);
1530 * gst_element_send_event:
1531 * @element: a #GstElement to send the event to.
1532 * @event: (transfer full): the #GstEvent to send to the element.
1534 * Sends an event to an element. If the element doesn't implement an
1535 * event handler, the event will be pushed on a random linked sink pad for
1536 * upstream events or a random linked source pad for downstream events.
1538 * This function takes owership of the provided event so you should
1539 * gst_event_ref() it if you want to reuse the event after this call.
1541 * Returns: %TRUE if the event was handled.
1546 gst_element_send_event (GstElement * element, GstEvent * event)
1548 GstElementClass *oclass;
1549 gboolean result = FALSE;
1551 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1552 g_return_val_if_fail (event != NULL, FALSE);
1554 oclass = GST_ELEMENT_GET_CLASS (element);
1556 GST_STATE_LOCK (element);
1557 if (oclass->send_event) {
1558 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1559 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1560 result = oclass->send_event (element, event);
1562 result = gst_element_default_send_event (element, event);
1564 GST_STATE_UNLOCK (element);
1571 * @element: a #GstElement to send the event to.
1572 * @rate: The new playback rate
1573 * @format: The format of the seek values
1574 * @flags: The optional seek flags.
1575 * @cur_type: The type and flags for the new current position
1576 * @cur: The value of the new current position
1577 * @stop_type: The type and flags for the new stop position
1578 * @stop: The value of the new stop position
1580 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1581 * the parameters. The seek event is sent to the element using
1582 * gst_element_send_event().
1584 * Returns: %TRUE if the event was handled.
1589 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1590 GstSeekFlags flags, GstSeekType cur_type, gint64 cur,
1591 GstSeekType stop_type, gint64 stop)
1596 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1599 gst_event_new_seek (rate, format, flags, cur_type, cur, stop_type, stop);
1600 result = gst_element_send_event (element, event);
1606 * gst_element_get_query_types:
1607 * @element: a #GstElement to query
1609 * Get an array of query types from the element.
1610 * If the element doesn't implement a query types function,
1611 * the query will be forwarded to the peer of a random linked sink pad.
1613 * Returns: An array of #GstQueryType elements that should not
1614 * be freed or modified.
1618 const GstQueryType *
1619 gst_element_get_query_types (GstElement * element)
1621 GstElementClass *oclass;
1622 const GstQueryType *result = NULL;
1624 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1626 oclass = GST_ELEMENT_GET_CLASS (element);
1628 if (oclass->get_query_types) {
1629 result = oclass->get_query_types (element);
1631 GstPad *pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1634 GstPad *peer = gst_pad_get_peer (pad);
1637 result = gst_pad_get_query_types (peer);
1639 gst_object_unref (peer);
1641 gst_object_unref (pad);
1648 gst_element_default_query (GstElement * element, GstQuery * query)
1650 gboolean result = FALSE;
1653 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1655 result = gst_pad_query (pad, query);
1657 gst_object_unref (pad);
1659 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1661 GstPad *peer = gst_pad_get_peer (pad);
1664 result = gst_pad_query (peer, query);
1666 gst_object_unref (peer);
1668 gst_object_unref (pad);
1675 * gst_element_query:
1676 * @element: a #GstElement to perform the query on.
1677 * @query: (transfer none): the #GstQuery.
1679 * Performs a query on the given element.
1681 * For elements that don't implement a query handler, this function
1682 * forwards the query to a random srcpad or to the peer of a
1683 * random linked sinkpad of this element.
1685 * Please note that some queries might need a running pipeline to work.
1687 * Returns: TRUE if the query could be performed.
1692 gst_element_query (GstElement * element, GstQuery * query)
1694 GstElementClass *oclass;
1695 gboolean result = FALSE;
1697 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1698 g_return_val_if_fail (query != NULL, FALSE);
1700 oclass = GST_ELEMENT_GET_CLASS (element);
1702 if (oclass->query) {
1703 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1704 GST_ELEMENT_NAME (element));
1705 result = oclass->query (element, query);
1707 result = gst_element_default_query (element, query);
1713 * gst_element_post_message:
1714 * @element: a #GstElement posting the message
1715 * @message: (transfer full): a #GstMessage to post
1717 * Post a message on the element's #GstBus. This function takes ownership of the
1718 * message; if you want to access the message after this call, you should add an
1719 * additional reference before calling.
1721 * Returns: %TRUE if the message was successfully posted. The function returns
1722 * %FALSE if the element did not have a bus.
1727 gst_element_post_message (GstElement * element, GstMessage * message)
1730 gboolean result = FALSE;
1732 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1733 g_return_val_if_fail (message != NULL, FALSE);
1735 GST_OBJECT_LOCK (element);
1738 if (G_UNLIKELY (bus == NULL))
1741 gst_object_ref (bus);
1742 GST_OBJECT_UNLOCK (element);
1744 /* we release the element lock when posting the message so that any
1745 * (synchronous) message handlers can operate on the element */
1746 result = gst_bus_post (bus, message);
1747 gst_object_unref (bus);
1754 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1755 "not posting message %p: no bus", message);
1756 GST_OBJECT_UNLOCK (element);
1757 gst_message_unref (message);
1763 * _gst_element_error_printf:
1764 * @format: the printf-like format to use, or %NULL
1766 * This function is only used internally by the gst_element_error() macro.
1768 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1774 _gst_element_error_printf (const gchar * format, ...)
1784 va_start (args, format);
1785 buffer = g_strdup_vprintf (format, args);
1791 * gst_element_message_full:
1792 * @element: a #GstElement to send message from
1793 * @type: the #GstMessageType
1794 * @domain: the GStreamer GError domain this message belongs to
1795 * @code: the GError code belonging to the domain
1796 * @text: (allow-none) (transfer full): an allocated text string to be used
1797 * as a replacement for the default message connected to code,
1799 * @debug: (allow-none) (transfer full): an allocated debug message to be
1800 * used as a replacement for the default debugging information,
1802 * @file: the source code file where the error was generated
1803 * @function: the source code function where the error was generated
1804 * @line: the source code line where the error was generated
1806 * Post an error, warning or info message on the bus from inside an element.
1808 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1809 * #GST_MESSAGE_INFO.
1813 void gst_element_message_full
1814 (GstElement * element, GstMessageType type,
1815 GQuark domain, gint code, gchar * text,
1816 gchar * debug, const gchar * file, const gchar * function, gint line)
1818 GError *gerror = NULL;
1822 gboolean has_debug = TRUE;
1823 GstMessage *message = NULL;
1826 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1827 g_return_if_fail (GST_IS_ELEMENT (element));
1828 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1829 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1831 /* check if we send the given text or the default error text */
1832 if ((text == NULL) || (text[0] == 0)) {
1833 /* text could have come from g_strdup_printf (""); */
1835 sent_text = gst_error_get_message (domain, code);
1839 /* construct a sent_debug with extra information from source */
1840 if ((debug == NULL) || (debug[0] == 0)) {
1841 /* debug could have come from g_strdup_printf (""); */
1845 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1847 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1848 file, line, function, name, debug);
1850 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1851 file, line, function, name);
1855 /* create gerror and post message */
1856 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1858 gerror = g_error_new_literal (domain, code, sent_text);
1861 case GST_MESSAGE_ERROR:
1863 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1865 case GST_MESSAGE_WARNING:
1866 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1869 case GST_MESSAGE_INFO:
1870 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1874 g_assert_not_reached ();
1877 gst_element_post_message (element, message);
1879 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1880 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1883 g_error_free (gerror);
1884 g_free (sent_debug);
1889 * gst_element_is_locked_state:
1890 * @element: a #GstElement.
1892 * Checks if the state of an element is locked.
1893 * If the state of an element is locked, state changes of the parent don't
1894 * affect the element.
1895 * This way you can leave currently unused elements inside bins. Just lock their
1896 * state before changing the state from #GST_STATE_NULL.
1900 * Returns: TRUE, if the element's state is locked.
1903 gst_element_is_locked_state (GstElement * element)
1907 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1909 GST_OBJECT_LOCK (element);
1910 result = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1911 GST_OBJECT_UNLOCK (element);
1917 * gst_element_set_locked_state:
1918 * @element: a #GstElement
1919 * @locked_state: TRUE to lock the element's state
1921 * Locks the state of an element, so state changes of the parent don't affect
1922 * this element anymore.
1926 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1927 * or the elements state-locking needed no change.
1930 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1934 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1936 GST_OBJECT_LOCK (element);
1937 old = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1939 if (G_UNLIKELY (old == locked_state))
1943 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1944 GST_ELEMENT_NAME (element));
1945 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_LOCKED_STATE);
1947 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1948 GST_ELEMENT_NAME (element));
1949 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_LOCKED_STATE);
1951 GST_OBJECT_UNLOCK (element);
1957 GST_CAT_DEBUG (GST_CAT_STATES,
1958 "elements %s was already in locked state %d",
1959 GST_ELEMENT_NAME (element), old);
1960 GST_OBJECT_UNLOCK (element);
1967 * gst_element_sync_state_with_parent:
1968 * @element: a #GstElement.
1970 * Tries to change the state of the element to the same as its parent.
1971 * If this function returns FALSE, the state of element is undefined.
1973 * Returns: TRUE, if the element's state could be synced to the parent's state.
1978 gst_element_sync_state_with_parent (GstElement * element)
1982 GstStateChangeReturn ret;
1984 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1986 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1987 GstState parent_current, parent_pending;
1989 GST_OBJECT_LOCK (parent);
1990 parent_current = GST_STATE (parent);
1991 parent_pending = GST_STATE_PENDING (parent);
1992 GST_OBJECT_UNLOCK (parent);
1994 /* set to pending if there is one, else we set it to the current state of
1996 if (parent_pending != GST_STATE_VOID_PENDING)
1997 target = parent_pending;
1999 target = parent_current;
2001 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2002 "syncing state (%s) to parent %s %s (%s, %s)",
2003 gst_element_state_get_name (GST_STATE (element)),
2004 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
2005 gst_element_state_get_name (parent_current),
2006 gst_element_state_get_name (parent_pending));
2008 ret = gst_element_set_state (element, target);
2009 if (ret == GST_STATE_CHANGE_FAILURE)
2012 gst_object_unref (parent);
2016 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
2023 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2024 "syncing state failed (%s)",
2025 gst_element_state_change_return_get_name (ret));
2026 gst_object_unref (parent);
2032 static GstStateChangeReturn
2033 gst_element_get_state_func (GstElement * element,
2034 GstState * state, GstState * pending, GstClockTime timeout)
2036 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2037 GstState old_pending;
2039 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2040 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2042 GST_OBJECT_LOCK (element);
2043 ret = GST_STATE_RETURN (element);
2044 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2045 gst_element_state_change_return_get_name (ret));
2047 /* we got an error, report immediately */
2048 if (ret == GST_STATE_CHANGE_FAILURE)
2051 /* we got no_preroll, report immediatly */
2052 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2055 /* no need to wait async if we are not async */
2056 if (ret != GST_STATE_CHANGE_ASYNC)
2059 old_pending = GST_STATE_PENDING (element);
2060 if (old_pending != GST_STATE_VOID_PENDING) {
2061 GTimeVal *timeval, abstimeout;
2064 if (timeout != GST_CLOCK_TIME_NONE) {
2065 glong add = timeout / 1000;
2070 /* make timeout absolute */
2071 g_get_current_time (&abstimeout);
2072 g_time_val_add (&abstimeout, add);
2073 timeval = &abstimeout;
2077 /* get cookie to detect state changes during waiting */
2078 cookie = element->state_cookie;
2080 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2081 "waiting for element to commit state");
2083 /* we have a pending state change, wait for it to complete */
2084 if (!GST_STATE_TIMED_WAIT (element, timeval)) {
2085 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2086 /* timeout triggered */
2087 ret = GST_STATE_CHANGE_ASYNC;
2089 if (cookie != element->state_cookie)
2092 /* could be success or failure */
2093 if (old_pending == GST_STATE (element)) {
2094 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2095 ret = GST_STATE_CHANGE_SUCCESS;
2097 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2098 ret = GST_STATE_CHANGE_FAILURE;
2101 /* if nothing is pending anymore we can return SUCCESS */
2102 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2103 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2104 ret = GST_STATE_CHANGE_SUCCESS;
2110 *state = GST_STATE (element);
2112 *pending = GST_STATE_PENDING (element);
2114 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2115 "state current: %s, pending: %s, result: %s",
2116 gst_element_state_get_name (GST_STATE (element)),
2117 gst_element_state_get_name (GST_STATE_PENDING (element)),
2118 gst_element_state_change_return_get_name (ret));
2119 GST_OBJECT_UNLOCK (element);
2126 *state = GST_STATE_VOID_PENDING;
2128 *pending = GST_STATE_VOID_PENDING;
2130 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2132 GST_OBJECT_UNLOCK (element);
2134 return GST_STATE_CHANGE_FAILURE;
2139 * gst_element_get_state:
2140 * @element: a #GstElement to get the state of.
2141 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2143 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2144 * state. Can be %NULL.
2145 * @timeout: a #GstClockTime to specify the timeout for an async
2146 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2148 * Gets the state of the element.
2150 * For elements that performed an ASYNC state change, as reported by
2151 * gst_element_set_state(), this function will block up to the
2152 * specified timeout value for the state change to complete.
2153 * If the element completes the state change or goes into
2154 * an error, this function returns immediately with a return value of
2155 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2157 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2158 * returns the current and pending state immediately.
2160 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2161 * successfully changed its state but is not able to provide data yet.
2162 * This mostly happens for live sources that only produce data in
2163 * %GST_STATE_PLAYING. While the state change return is equivalent to
2164 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2165 * some sink elements might not be able to complete their state change because
2166 * an element is not producing data to complete the preroll. When setting the
2167 * element to playing, the preroll will complete and playback will start.
2169 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2170 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2171 * element is still performing a state change or
2172 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2176 GstStateChangeReturn
2177 gst_element_get_state (GstElement * element,
2178 GstState * state, GstState * pending, GstClockTime timeout)
2180 GstElementClass *oclass;
2181 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2183 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2185 oclass = GST_ELEMENT_GET_CLASS (element);
2187 if (oclass->get_state)
2188 result = (oclass->get_state) (element, state, pending, timeout);
2194 * gst_element_abort_state:
2195 * @element: a #GstElement to abort the state of.
2197 * Abort the state change of the element. This function is used
2198 * by elements that do asynchronous state changes and find out
2199 * something is wrong.
2201 * This function should be called with the STATE_LOCK held.
2206 gst_element_abort_state (GstElement * element)
2210 #ifndef GST_DISABLE_GST_DEBUG
2214 g_return_if_fail (GST_IS_ELEMENT (element));
2216 GST_OBJECT_LOCK (element);
2217 pending = GST_STATE_PENDING (element);
2219 if (pending == GST_STATE_VOID_PENDING ||
2220 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2221 goto nothing_aborted;
2223 #ifndef GST_DISABLE_GST_DEBUG
2224 old_state = GST_STATE (element);
2226 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2227 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2228 gst_element_state_get_name (pending));
2232 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2234 GST_STATE_BROADCAST (element);
2235 GST_OBJECT_UNLOCK (element);
2241 GST_OBJECT_UNLOCK (element);
2246 /* Not static because GstBin has manual state handling too */
2248 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2249 GstState newstate, GstState pending)
2251 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2252 GstMessage *message;
2254 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2255 "notifying about state-changed %s to %s (%s pending)",
2256 gst_element_state_get_name (oldstate),
2257 gst_element_state_get_name (newstate),
2258 gst_element_state_get_name (pending));
2260 if (klass->state_changed)
2261 klass->state_changed (element, oldstate, newstate, pending);
2263 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2264 oldstate, newstate, pending);
2265 gst_element_post_message (element, message);
2269 * gst_element_continue_state:
2270 * @element: a #GstElement to continue the state change of.
2271 * @ret: The previous state return value
2273 * Commit the state change of the element and proceed to the next
2274 * pending state if any. This function is used
2275 * by elements that do asynchronous state changes.
2276 * The core will normally call this method automatically when an
2277 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2279 * If after calling this method the element still has not reached
2280 * the pending state, the next state change is performed.
2282 * This method is used internally and should normally not be called by plugins
2285 * Returns: The result of the commit state change.
2289 GstStateChangeReturn
2290 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2292 GstStateChangeReturn old_ret;
2293 GstState old_state, old_next;
2294 GstState current, next, pending;
2295 GstStateChange transition;
2297 GST_OBJECT_LOCK (element);
2298 old_ret = GST_STATE_RETURN (element);
2299 GST_STATE_RETURN (element) = ret;
2300 pending = GST_STATE_PENDING (element);
2302 /* check if there is something to commit */
2303 if (pending == GST_STATE_VOID_PENDING)
2304 goto nothing_pending;
2306 old_state = GST_STATE (element);
2307 /* this is the state we should go to next */
2308 old_next = GST_STATE_NEXT (element);
2309 /* update current state */
2310 current = GST_STATE (element) = old_next;
2312 /* see if we reached the final state */
2313 if (pending == current)
2316 next = GST_STATE_GET_NEXT (current, pending);
2317 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2319 GST_STATE_NEXT (element) = next;
2321 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2322 GST_OBJECT_UNLOCK (element);
2324 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2325 "committing state from %s to %s, pending %s, next %s",
2326 gst_element_state_get_name (old_state),
2327 gst_element_state_get_name (old_next),
2328 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2330 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2332 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2333 "continue state change %s to %s, final %s",
2334 gst_element_state_get_name (current),
2335 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2337 ret = gst_element_change_state (element, transition);
2343 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2344 GST_OBJECT_UNLOCK (element);
2349 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2350 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2352 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2353 "completed state change to %s", gst_element_state_get_name (pending));
2354 GST_OBJECT_UNLOCK (element);
2356 /* don't post silly messages with the same state. This can happen
2357 * when an element state is changed to what it already was. For bins
2358 * this can be the result of a lost state, which we check with the
2359 * previous return value.
2360 * We do signal the cond though as a _get_state() might be blocking
2362 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2363 _priv_gst_element_state_changed (element, old_state, old_next,
2364 GST_STATE_VOID_PENDING);
2366 GST_STATE_BROADCAST (element);
2373 * gst_element_lost_state:
2374 * @element: a #GstElement the state is lost of
2375 * @new_base_time: if a new base time should be distributed
2377 * Brings the element to the lost state. The current state of the
2378 * element is copied to the pending state so that any call to
2379 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2381 * An ASYNC_START message is posted with indication to distribute a new
2382 * base_time to the element when @new_base_time is %TRUE.
2383 * If the element was PLAYING, it will go to PAUSED. The element
2384 * will be restored to its PLAYING state by the parent pipeline when it
2387 * This is mostly used for elements that lost their preroll buffer
2388 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2389 * they will go to their pending state again when a new preroll buffer is
2390 * queued. This function can only be called when the element is currently
2391 * not in error or an async state change.
2393 * This function is used internally and should normally not be called from
2394 * plugins or applications.
2397 gst_element_lost_state (GstElement * element, gboolean new_base_time)
2399 GstState old_state, new_state;
2400 GstMessage *message;
2402 g_return_if_fail (GST_IS_ELEMENT (element));
2404 GST_OBJECT_LOCK (element);
2405 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2408 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2409 goto only_async_start;
2411 old_state = GST_STATE (element);
2413 /* when we were PLAYING, the new state is PAUSED. We will also not
2414 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2415 * when we preroll. */
2416 if (old_state > GST_STATE_PAUSED)
2417 new_state = GST_STATE_PAUSED;
2419 new_state = old_state;
2421 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2422 "lost state of %s to %s", gst_element_state_get_name (old_state),
2423 gst_element_state_get_name (new_state));
2425 GST_STATE (element) = new_state;
2426 GST_STATE_NEXT (element) = new_state;
2427 GST_STATE_PENDING (element) = new_state;
2428 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2430 GST_ELEMENT_START_TIME (element) = 0;
2431 GST_OBJECT_UNLOCK (element);
2433 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2436 gst_message_new_async_start (GST_OBJECT_CAST (element), new_base_time);
2437 gst_element_post_message (element, message);
2443 GST_OBJECT_UNLOCK (element);
2448 GST_OBJECT_UNLOCK (element);
2450 message = gst_message_new_async_start (GST_OBJECT_CAST (element), TRUE);
2451 gst_element_post_message (element, message);
2457 * gst_element_set_state:
2458 * @element: a #GstElement to change state of.
2459 * @state: the element's new #GstState.
2461 * Sets the state of the element. This function will try to set the
2462 * requested state by going through all the intermediary states and calling
2463 * the class's state change function for each.
2465 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2466 * element will perform the remainder of the state change asynchronously in
2468 * An application can use gst_element_get_state() to wait for the completion
2469 * of the state change or it can wait for a state change message on the bus.
2471 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2472 * #GST_STATE_CHANGE_ASYNC.
2474 * Returns: Result of the state change using #GstStateChangeReturn.
2478 GstStateChangeReturn
2479 gst_element_set_state (GstElement * element, GstState state)
2481 GstElementClass *oclass;
2482 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2484 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2486 oclass = GST_ELEMENT_GET_CLASS (element);
2488 if (oclass->set_state)
2489 result = (oclass->set_state) (element, state);
2495 * default set state function, calculates the next state based
2496 * on current state and calls the change_state function
2498 static GstStateChangeReturn
2499 gst_element_set_state_func (GstElement * element, GstState state)
2501 GstState current, next, old_pending;
2502 GstStateChangeReturn ret;
2503 GstStateChange transition;
2504 GstStateChangeReturn old_ret;
2506 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2508 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2509 gst_element_state_get_name (state));
2511 /* state lock is taken to protect the set_state() and get_state()
2512 * procedures, it does not lock any variables. */
2513 GST_STATE_LOCK (element);
2515 /* now calculate how to get to the new state */
2516 GST_OBJECT_LOCK (element);
2517 old_ret = GST_STATE_RETURN (element);
2518 /* previous state change returned an error, remove all pending
2519 * and next states */
2520 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2521 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2522 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2523 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2526 current = GST_STATE (element);
2527 next = GST_STATE_NEXT (element);
2528 old_pending = GST_STATE_PENDING (element);
2530 /* this is the (new) state we should go to. TARGET is the last state we set on
2532 if (state != GST_STATE_TARGET (element)) {
2533 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2534 "setting target state to %s", gst_element_state_get_name (state));
2535 GST_STATE_TARGET (element) = state;
2536 /* increment state cookie so that we can track each state change. We only do
2537 * this if this is actually a new state change. */
2538 element->state_cookie++;
2540 GST_STATE_PENDING (element) = state;
2542 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2543 "current %s, old_pending %s, next %s, old return %s",
2544 gst_element_state_get_name (current),
2545 gst_element_state_get_name (old_pending),
2546 gst_element_state_get_name (next),
2547 gst_element_state_change_return_get_name (old_ret));
2549 /* if the element was busy doing a state change, we just update the
2550 * target state, it'll get to it async then. */
2551 if (old_pending != GST_STATE_VOID_PENDING) {
2552 /* upwards state change will happen ASYNC */
2553 if (old_pending <= state)
2555 /* element is going to this state already */
2556 else if (next == state)
2558 /* element was performing an ASYNC upward state change and
2559 * we request to go downward again. Start from the next pending
2561 else if (next > state
2562 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2566 next = GST_STATE_GET_NEXT (current, state);
2567 /* now we store the next state */
2568 GST_STATE_NEXT (element) = next;
2569 /* mark busy, we need to check that there is actually a state change
2570 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2571 * the default element change_state function has no way to know what the
2572 * old value was... could consider this a FIXME...*/
2573 if (current != next)
2574 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2576 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2578 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2579 "%s: setting state from %s to %s",
2580 (next != state ? "intermediate" : "final"),
2581 gst_element_state_get_name (current), gst_element_state_get_name (next));
2583 /* now signal any waiters, they will error since the cookie was incremented */
2584 GST_STATE_BROADCAST (element);
2586 GST_OBJECT_UNLOCK (element);
2588 ret = gst_element_change_state (element, transition);
2590 GST_STATE_UNLOCK (element);
2592 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2593 gst_element_state_change_return_get_name (ret));
2599 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2600 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2601 "element was busy with async state change");
2602 GST_OBJECT_UNLOCK (element);
2604 GST_STATE_UNLOCK (element);
2606 return GST_STATE_CHANGE_ASYNC;
2611 * gst_element_change_state:
2612 * @element: a #GstElement
2613 * @transition: the requested transition
2615 * Perform @transition on @element.
2617 * This function must be called with STATE_LOCK held and is mainly used
2620 * Returns: the #GstStateChangeReturn of the state transition.
2622 GstStateChangeReturn
2623 gst_element_change_state (GstElement * element, GstStateChange transition)
2625 GstElementClass *oclass;
2626 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2628 oclass = GST_ELEMENT_GET_CLASS (element);
2630 /* call the state change function so it can set the state */
2631 if (oclass->change_state)
2632 ret = (oclass->change_state) (element, transition);
2634 ret = GST_STATE_CHANGE_FAILURE;
2637 case GST_STATE_CHANGE_FAILURE:
2638 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2639 "have FAILURE change_state return");
2640 /* state change failure */
2641 gst_element_abort_state (element);
2643 case GST_STATE_CHANGE_ASYNC:
2647 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2648 "element will change state ASYNC");
2650 target = GST_STATE_TARGET (element);
2652 if (target > GST_STATE_READY)
2655 /* else we just continue the state change downwards */
2656 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2657 "forcing commit state %s <= %s",
2658 gst_element_state_get_name (target),
2659 gst_element_state_get_name (GST_STATE_READY));
2661 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2664 case GST_STATE_CHANGE_SUCCESS:
2665 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2666 "element changed state SUCCESS");
2667 /* we can commit the state now which will proceeed to
2669 ret = gst_element_continue_state (element, ret);
2671 case GST_STATE_CHANGE_NO_PREROLL:
2672 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2673 "element changed state NO_PREROLL");
2674 /* we can commit the state now which will proceeed to
2676 ret = gst_element_continue_state (element, ret);
2679 goto invalid_return;
2682 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2687 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2695 GST_OBJECT_LOCK (element);
2696 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2697 g_critical ("%s: unknown return value %d from a state change function",
2698 GST_ELEMENT_NAME (element), ret);
2700 /* we are in error now */
2701 ret = GST_STATE_CHANGE_FAILURE;
2702 GST_STATE_RETURN (element) = ret;
2703 GST_OBJECT_UNLOCK (element);
2709 /* gst_iterator_fold functions for pads_activate
2710 * Stop the iterator if activating one pad failed. */
2712 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2714 GstPad *pad = g_value_get_object (vpad);
2715 gboolean cont = TRUE;
2717 if (!(cont = gst_pad_set_active (pad, *active)))
2718 g_value_set_boolean (ret, FALSE);
2723 /* returns false on error or early cutout of the fold, true if all
2724 * pads in @iter were (de)activated successfully. */
2726 iterator_activate_fold_with_resync (GstIterator * iter,
2727 GstIteratorFoldFunction func, gpointer user_data)
2729 GstIteratorResult ires;
2732 /* no need to unset this later, it's just a boolean */
2733 g_value_init (&ret, G_TYPE_BOOLEAN);
2734 g_value_set_boolean (&ret, TRUE);
2737 ires = gst_iterator_fold (iter, func, &ret, user_data);
2739 case GST_ITERATOR_RESYNC:
2740 /* need to reset the result again */
2741 g_value_set_boolean (&ret, TRUE);
2742 gst_iterator_resync (iter);
2744 case GST_ITERATOR_DONE:
2745 /* all pads iterated, return collected value */
2748 /* iterator returned _ERROR or premature end with _OK,
2749 * mark an error and exit */
2750 g_value_set_boolean (&ret, FALSE);
2755 /* return collected value */
2756 return g_value_get_boolean (&ret);
2759 /* is called with STATE_LOCK
2761 * Pads are activated from source pads to sinkpads.
2764 gst_element_pads_activate (GstElement * element, gboolean active)
2769 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2770 "pads_activate with active %d", active);
2772 iter = gst_element_iterate_src_pads (element);
2774 iterator_activate_fold_with_resync (iter,
2775 (GstIteratorFoldFunction) activate_pads, &active);
2776 gst_iterator_free (iter);
2777 if (G_UNLIKELY (!res))
2780 iter = gst_element_iterate_sink_pads (element);
2782 iterator_activate_fold_with_resync (iter,
2783 (GstIteratorFoldFunction) activate_pads, &active);
2784 gst_iterator_free (iter);
2785 if (G_UNLIKELY (!res))
2788 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2789 "pads_activate successful");
2796 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2797 "source pads_activate failed");
2802 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2803 "sink pads_activate failed");
2808 /* is called with STATE_LOCK */
2809 static GstStateChangeReturn
2810 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2812 GstState state, next;
2813 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2815 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2817 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2818 next = GST_STATE_TRANSITION_NEXT (transition);
2820 /* if the element already is in the given state, we just return success */
2821 if (next == GST_STATE_VOID_PENDING || state == next)
2824 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2825 "default handler tries setting state from %s to %s (%04x)",
2826 gst_element_state_get_name (state),
2827 gst_element_state_get_name (next), transition);
2829 switch (transition) {
2830 case GST_STATE_CHANGE_NULL_TO_READY:
2832 case GST_STATE_CHANGE_READY_TO_PAUSED:
2833 if (!gst_element_pads_activate (element, TRUE)) {
2834 result = GST_STATE_CHANGE_FAILURE;
2837 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2839 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2841 case GST_STATE_CHANGE_PAUSED_TO_READY:
2842 case GST_STATE_CHANGE_READY_TO_NULL:
2843 /* deactivate pads in both cases, since they are activated on
2844 ready->paused but the element might not have made it to paused */
2845 if (!gst_element_pads_activate (element, FALSE)) {
2846 result = GST_STATE_CHANGE_FAILURE;
2850 /* this will catch real but unhandled state changes;
2851 * can only be caused by:
2852 * - a new state was added
2853 * - somehow the element was asked to jump across an intermediate state
2855 g_warning ("Unhandled state change from %s to %s",
2856 gst_element_state_get_name (state),
2857 gst_element_state_get_name (next));
2864 GST_OBJECT_LOCK (element);
2865 result = GST_STATE_RETURN (element);
2866 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2867 "element is already in the %s state",
2868 gst_element_state_get_name (state));
2869 GST_OBJECT_UNLOCK (element);
2876 * gst_element_get_factory:
2877 * @element: a #GstElement to request the element factory of.
2879 * Retrieves the factory that was used to create this element.
2881 * Returns: (transfer none): the #GstElementFactory used for creating this
2882 * element. no refcounting is needed.
2885 gst_element_get_factory (GstElement * element)
2887 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2889 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2893 gst_element_dispose (GObject * object)
2895 GstElement *element = GST_ELEMENT_CAST (object);
2899 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2901 if (GST_STATE (element) != GST_STATE_NULL)
2904 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2905 "removing %d pads", g_list_length (element->pads));
2906 /* first we break all our links with the outside */
2907 while (element->pads && element->pads->data) {
2908 /* don't call _remove_pad with NULL */
2909 gst_element_remove_pad (element, GST_PAD_CAST (element->pads->data));
2911 if (G_UNLIKELY (element->pads != NULL)) {
2912 g_critical ("could not remove pads from element %s",
2913 GST_STR_NULL (GST_OBJECT_NAME (object)));
2916 GST_OBJECT_LOCK (element);
2917 clock_p = &element->clock;
2918 bus_p = &element->bus;
2919 gst_object_replace ((GstObject **) clock_p, NULL);
2920 gst_object_replace ((GstObject **) bus_p, NULL);
2921 GST_OBJECT_UNLOCK (element);
2923 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2925 G_OBJECT_CLASS (parent_class)->dispose (object);
2934 is_locked = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
2936 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2938 "You need to explicitly set elements to the NULL state before\n"
2939 "dropping the final reference, to allow them to clean up.\n"
2940 "This problem may also be caused by a refcounting bug in the\n"
2941 "application or some element.\n",
2942 GST_OBJECT_NAME (element),
2943 gst_element_state_get_name (GST_STATE (element)),
2944 is_locked ? " (locked)" : "");
2950 gst_element_finalize (GObject * object)
2952 GstElement *element = GST_ELEMENT_CAST (object);
2954 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2956 GST_STATE_LOCK (element);
2957 if (element->state_cond)
2958 g_cond_free (element->state_cond);
2959 element->state_cond = NULL;
2960 GST_STATE_UNLOCK (element);
2961 g_static_rec_mutex_free (element->state_lock);
2962 g_slice_free (GStaticRecMutex, element->state_lock);
2963 element->state_lock = NULL;
2965 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2967 G_OBJECT_CLASS (parent_class)->finalize (object);
2971 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2975 g_return_if_fail (GST_IS_ELEMENT (element));
2977 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2979 GST_OBJECT_LOCK (element);
2980 bus_p = &GST_ELEMENT_BUS (element);
2981 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
2982 GST_OBJECT_UNLOCK (element);
2986 * gst_element_set_bus:
2987 * @element: a #GstElement to set the bus of.
2988 * @bus: (transfer none): the #GstBus to set.
2990 * Sets the bus of the element. Increases the refcount on the bus.
2991 * For internal use only, unless you're testing elements.
2996 gst_element_set_bus (GstElement * element, GstBus * bus)
2998 GstElementClass *oclass;
3000 g_return_if_fail (GST_IS_ELEMENT (element));
3002 oclass = GST_ELEMENT_GET_CLASS (element);
3004 if (oclass->set_bus)
3005 oclass->set_bus (element, bus);
3009 * gst_element_get_bus:
3010 * @element: a #GstElement to get the bus of.
3012 * Returns the bus of the element. Note that only a #GstPipeline will provide a
3013 * bus for the application.
3015 * Returns: (transfer full): the element's #GstBus. unref after usage.
3020 gst_element_get_bus (GstElement * element)
3022 GstBus *result = NULL;
3024 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3026 GST_OBJECT_LOCK (element);
3027 if ((result = GST_ELEMENT_BUS (element)))
3028 gst_object_ref (result);
3029 GST_OBJECT_UNLOCK (element);
3031 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,