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_pad_template_list:
1354 * @element_class: a #GstElementClass to get pad templates of.
1356 * Retrieves a list of the pad templates associated with @element_class. The
1357 * list must not be modified by the calling code.
1358 * <note>If you use this function in the #GInstanceInitFunc of an object class
1359 * that has subclasses, make sure to pass the g_class parameter of the
1360 * #GInstanceInitFunc here.</note>
1362 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1366 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1368 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1370 return element_class->padtemplates;
1374 * gst_element_class_get_pad_template:
1375 * @element_class: a #GstElementClass to get the pad template of.
1376 * @name: the name of the #GstPadTemplate to get.
1378 * Retrieves a padtemplate from @element_class with the given name.
1379 * <note>If you use this function in the #GInstanceInitFunc of an object class
1380 * that has subclasses, make sure to pass the g_class parameter of the
1381 * #GInstanceInitFunc here.</note>
1383 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1384 * if none was found. No unreferencing is necessary.
1387 gst_element_class_get_pad_template (GstElementClass *
1388 element_class, const gchar * name)
1392 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1393 g_return_val_if_fail (name != NULL, NULL);
1395 padlist = element_class->padtemplates;
1398 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1400 if (strcmp (padtempl->name_template, name) == 0)
1403 padlist = g_list_next (padlist);
1409 static GstPadTemplate *
1410 gst_element_class_get_request_pad_template (GstElementClass *
1411 element_class, const gchar * name)
1413 GstPadTemplate *tmpl;
1415 tmpl = gst_element_class_get_pad_template (element_class, name);
1416 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1422 /* get a random pad on element of the given direction.
1423 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1426 gst_element_get_random_pad (GstElement * element,
1427 gboolean need_linked, GstPadDirection dir)
1429 GstPad *result = NULL;
1432 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1436 GST_OBJECT_LOCK (element);
1437 pads = element->srcpads;
1440 GST_OBJECT_LOCK (element);
1441 pads = element->sinkpads;
1444 goto wrong_direction;
1446 for (; pads; pads = g_list_next (pads)) {
1447 GstPad *pad = GST_PAD_CAST (pads->data);
1449 GST_OBJECT_LOCK (pad);
1450 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1451 GST_DEBUG_PAD_NAME (pad));
1453 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1454 /* if we require a linked pad, and it is not linked, continue the
1456 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1457 GST_DEBUG_PAD_NAME (pad));
1458 GST_OBJECT_UNLOCK (pad);
1461 /* found a pad, stop search */
1462 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1463 GST_DEBUG_PAD_NAME (pad));
1464 GST_OBJECT_UNLOCK (pad);
1470 gst_object_ref (result);
1472 GST_OBJECT_UNLOCK (element);
1476 /* ERROR handling */
1479 g_warning ("unknown pad direction %d", dir);
1485 gst_element_default_send_event (GstElement * element, GstEvent * event)
1487 gboolean result = FALSE;
1490 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1491 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1492 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1495 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1496 "pushing %s event to random %s pad %s:%s",
1497 GST_EVENT_TYPE_NAME (event),
1498 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1499 GST_DEBUG_PAD_NAME (pad));
1501 result = gst_pad_push_event (pad, event);
1502 gst_object_unref (pad);
1504 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1505 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1506 gst_event_unref (event);
1512 * gst_element_send_event:
1513 * @element: a #GstElement to send the event to.
1514 * @event: (transfer full): the #GstEvent to send to the element.
1516 * Sends an event to an element. If the element doesn't implement an
1517 * event handler, the event will be pushed on a random linked sink pad for
1518 * upstream events or a random linked source pad for downstream events.
1520 * This function takes owership of the provided event so you should
1521 * gst_event_ref() it if you want to reuse the event after this call.
1523 * Returns: %TRUE if the event was handled.
1528 gst_element_send_event (GstElement * element, GstEvent * event)
1530 GstElementClass *oclass;
1531 gboolean result = FALSE;
1533 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1534 g_return_val_if_fail (event != NULL, FALSE);
1536 oclass = GST_ELEMENT_GET_CLASS (element);
1538 GST_STATE_LOCK (element);
1539 if (oclass->send_event) {
1540 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1541 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1542 result = oclass->send_event (element, event);
1544 result = gst_element_default_send_event (element, event);
1546 GST_STATE_UNLOCK (element);
1553 * @element: a #GstElement to send the event to.
1554 * @rate: The new playback rate
1555 * @format: The format of the seek values
1556 * @flags: The optional seek flags.
1557 * @cur_type: The type and flags for the new current position
1558 * @cur: The value of the new current position
1559 * @stop_type: The type and flags for the new stop position
1560 * @stop: The value of the new stop position
1562 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1563 * the parameters. The seek event is sent to the element using
1564 * gst_element_send_event().
1566 * Returns: %TRUE if the event was handled.
1571 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1572 GstSeekFlags flags, GstSeekType cur_type, gint64 cur,
1573 GstSeekType stop_type, gint64 stop)
1578 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1581 gst_event_new_seek (rate, format, flags, cur_type, cur, stop_type, stop);
1582 result = gst_element_send_event (element, event);
1588 * gst_element_get_query_types:
1589 * @element: a #GstElement to query
1591 * Get an array of query types from the element.
1592 * If the element doesn't implement a query types function,
1593 * the query will be forwarded to the peer of a random linked sink pad.
1595 * Returns: An array of #GstQueryType elements that should not
1596 * be freed or modified.
1600 const GstQueryType *
1601 gst_element_get_query_types (GstElement * element)
1603 GstElementClass *oclass;
1604 const GstQueryType *result = NULL;
1606 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1608 oclass = GST_ELEMENT_GET_CLASS (element);
1610 if (oclass->get_query_types) {
1611 result = oclass->get_query_types (element);
1613 GstPad *pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1616 GstPad *peer = gst_pad_get_peer (pad);
1619 result = gst_pad_get_query_types (peer);
1621 gst_object_unref (peer);
1623 gst_object_unref (pad);
1630 gst_element_default_query (GstElement * element, GstQuery * query)
1632 gboolean result = FALSE;
1635 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1637 result = gst_pad_query (pad, query);
1639 gst_object_unref (pad);
1641 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1643 GstPad *peer = gst_pad_get_peer (pad);
1646 result = gst_pad_query (peer, query);
1648 gst_object_unref (peer);
1650 gst_object_unref (pad);
1657 * gst_element_query:
1658 * @element: a #GstElement to perform the query on.
1659 * @query: (transfer none): the #GstQuery.
1661 * Performs a query on the given element.
1663 * For elements that don't implement a query handler, this function
1664 * forwards the query to a random srcpad or to the peer of a
1665 * random linked sinkpad of this element.
1667 * Please note that some queries might need a running pipeline to work.
1669 * Returns: TRUE if the query could be performed.
1674 gst_element_query (GstElement * element, GstQuery * query)
1676 GstElementClass *oclass;
1677 gboolean result = FALSE;
1679 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1680 g_return_val_if_fail (query != NULL, FALSE);
1682 oclass = GST_ELEMENT_GET_CLASS (element);
1684 if (oclass->query) {
1685 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1686 GST_ELEMENT_NAME (element));
1687 result = oclass->query (element, query);
1689 result = gst_element_default_query (element, query);
1695 * gst_element_post_message:
1696 * @element: a #GstElement posting the message
1697 * @message: (transfer full): a #GstMessage to post
1699 * Post a message on the element's #GstBus. This function takes ownership of the
1700 * message; if you want to access the message after this call, you should add an
1701 * additional reference before calling.
1703 * Returns: %TRUE if the message was successfully posted. The function returns
1704 * %FALSE if the element did not have a bus.
1709 gst_element_post_message (GstElement * element, GstMessage * message)
1712 gboolean result = FALSE;
1714 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1715 g_return_val_if_fail (message != NULL, FALSE);
1717 GST_OBJECT_LOCK (element);
1720 if (G_UNLIKELY (bus == NULL))
1723 gst_object_ref (bus);
1724 GST_OBJECT_UNLOCK (element);
1726 /* we release the element lock when posting the message so that any
1727 * (synchronous) message handlers can operate on the element */
1728 result = gst_bus_post (bus, message);
1729 gst_object_unref (bus);
1736 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1737 "not posting message %p: no bus", message);
1738 GST_OBJECT_UNLOCK (element);
1739 gst_message_unref (message);
1745 * _gst_element_error_printf:
1746 * @format: the printf-like format to use, or %NULL
1748 * This function is only used internally by the gst_element_error() macro.
1750 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1756 _gst_element_error_printf (const gchar * format, ...)
1766 va_start (args, format);
1767 buffer = g_strdup_vprintf (format, args);
1773 * gst_element_message_full:
1774 * @element: a #GstElement to send message from
1775 * @type: the #GstMessageType
1776 * @domain: the GStreamer GError domain this message belongs to
1777 * @code: the GError code belonging to the domain
1778 * @text: (allow-none) (transfer full): an allocated text string to be used
1779 * as a replacement for the default message connected to code,
1781 * @debug: (allow-none) (transfer full): an allocated debug message to be
1782 * used as a replacement for the default debugging information,
1784 * @file: the source code file where the error was generated
1785 * @function: the source code function where the error was generated
1786 * @line: the source code line where the error was generated
1788 * Post an error, warning or info message on the bus from inside an element.
1790 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1791 * #GST_MESSAGE_INFO.
1795 void gst_element_message_full
1796 (GstElement * element, GstMessageType type,
1797 GQuark domain, gint code, gchar * text,
1798 gchar * debug, const gchar * file, const gchar * function, gint line)
1800 GError *gerror = NULL;
1804 gboolean has_debug = TRUE;
1805 GstMessage *message = NULL;
1808 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1809 g_return_if_fail (GST_IS_ELEMENT (element));
1810 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1811 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1813 /* check if we send the given text or the default error text */
1814 if ((text == NULL) || (text[0] == 0)) {
1815 /* text could have come from g_strdup_printf (""); */
1817 sent_text = gst_error_get_message (domain, code);
1821 /* construct a sent_debug with extra information from source */
1822 if ((debug == NULL) || (debug[0] == 0)) {
1823 /* debug could have come from g_strdup_printf (""); */
1827 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1829 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1830 file, line, function, name, debug);
1832 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1833 file, line, function, name);
1837 /* create gerror and post message */
1838 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1840 gerror = g_error_new_literal (domain, code, sent_text);
1843 case GST_MESSAGE_ERROR:
1845 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1847 case GST_MESSAGE_WARNING:
1848 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1851 case GST_MESSAGE_INFO:
1852 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1856 g_assert_not_reached ();
1859 gst_element_post_message (element, message);
1861 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1862 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1865 g_error_free (gerror);
1866 g_free (sent_debug);
1871 * gst_element_is_locked_state:
1872 * @element: a #GstElement.
1874 * Checks if the state of an element is locked.
1875 * If the state of an element is locked, state changes of the parent don't
1876 * affect the element.
1877 * This way you can leave currently unused elements inside bins. Just lock their
1878 * state before changing the state from #GST_STATE_NULL.
1882 * Returns: TRUE, if the element's state is locked.
1885 gst_element_is_locked_state (GstElement * element)
1889 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1891 GST_OBJECT_LOCK (element);
1892 result = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1893 GST_OBJECT_UNLOCK (element);
1899 * gst_element_set_locked_state:
1900 * @element: a #GstElement
1901 * @locked_state: TRUE to lock the element's state
1903 * Locks the state of an element, so state changes of the parent don't affect
1904 * this element anymore.
1908 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1909 * or the elements state-locking needed no change.
1912 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1916 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1918 GST_OBJECT_LOCK (element);
1919 old = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1921 if (G_UNLIKELY (old == locked_state))
1925 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1926 GST_ELEMENT_NAME (element));
1927 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_LOCKED_STATE);
1929 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1930 GST_ELEMENT_NAME (element));
1931 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_LOCKED_STATE);
1933 GST_OBJECT_UNLOCK (element);
1939 GST_CAT_DEBUG (GST_CAT_STATES,
1940 "elements %s was already in locked state %d",
1941 GST_ELEMENT_NAME (element), old);
1942 GST_OBJECT_UNLOCK (element);
1949 * gst_element_sync_state_with_parent:
1950 * @element: a #GstElement.
1952 * Tries to change the state of the element to the same as its parent.
1953 * If this function returns FALSE, the state of element is undefined.
1955 * Returns: TRUE, if the element's state could be synced to the parent's state.
1960 gst_element_sync_state_with_parent (GstElement * element)
1964 GstStateChangeReturn ret;
1966 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1968 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1969 GstState parent_current, parent_pending;
1971 GST_OBJECT_LOCK (parent);
1972 parent_current = GST_STATE (parent);
1973 parent_pending = GST_STATE_PENDING (parent);
1974 GST_OBJECT_UNLOCK (parent);
1976 /* set to pending if there is one, else we set it to the current state of
1978 if (parent_pending != GST_STATE_VOID_PENDING)
1979 target = parent_pending;
1981 target = parent_current;
1983 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1984 "syncing state (%s) to parent %s %s (%s, %s)",
1985 gst_element_state_get_name (GST_STATE (element)),
1986 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1987 gst_element_state_get_name (parent_current),
1988 gst_element_state_get_name (parent_pending));
1990 ret = gst_element_set_state (element, target);
1991 if (ret == GST_STATE_CHANGE_FAILURE)
1994 gst_object_unref (parent);
1998 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
2005 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2006 "syncing state failed (%s)",
2007 gst_element_state_change_return_get_name (ret));
2008 gst_object_unref (parent);
2014 static GstStateChangeReturn
2015 gst_element_get_state_func (GstElement * element,
2016 GstState * state, GstState * pending, GstClockTime timeout)
2018 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2019 GstState old_pending;
2021 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2022 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2024 GST_OBJECT_LOCK (element);
2025 ret = GST_STATE_RETURN (element);
2026 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2027 gst_element_state_change_return_get_name (ret));
2029 /* we got an error, report immediately */
2030 if (ret == GST_STATE_CHANGE_FAILURE)
2033 /* we got no_preroll, report immediatly */
2034 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2037 /* no need to wait async if we are not async */
2038 if (ret != GST_STATE_CHANGE_ASYNC)
2041 old_pending = GST_STATE_PENDING (element);
2042 if (old_pending != GST_STATE_VOID_PENDING) {
2043 GTimeVal *timeval, abstimeout;
2046 if (timeout != GST_CLOCK_TIME_NONE) {
2047 glong add = timeout / 1000;
2052 /* make timeout absolute */
2053 g_get_current_time (&abstimeout);
2054 g_time_val_add (&abstimeout, add);
2055 timeval = &abstimeout;
2059 /* get cookie to detect state changes during waiting */
2060 cookie = element->state_cookie;
2062 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2063 "waiting for element to commit state");
2065 /* we have a pending state change, wait for it to complete */
2066 if (!GST_STATE_TIMED_WAIT (element, timeval)) {
2067 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2068 /* timeout triggered */
2069 ret = GST_STATE_CHANGE_ASYNC;
2071 if (cookie != element->state_cookie)
2074 /* could be success or failure */
2075 if (old_pending == GST_STATE (element)) {
2076 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2077 ret = GST_STATE_CHANGE_SUCCESS;
2079 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2080 ret = GST_STATE_CHANGE_FAILURE;
2083 /* if nothing is pending anymore we can return SUCCESS */
2084 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2085 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2086 ret = GST_STATE_CHANGE_SUCCESS;
2092 *state = GST_STATE (element);
2094 *pending = GST_STATE_PENDING (element);
2096 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2097 "state current: %s, pending: %s, result: %s",
2098 gst_element_state_get_name (GST_STATE (element)),
2099 gst_element_state_get_name (GST_STATE_PENDING (element)),
2100 gst_element_state_change_return_get_name (ret));
2101 GST_OBJECT_UNLOCK (element);
2108 *state = GST_STATE_VOID_PENDING;
2110 *pending = GST_STATE_VOID_PENDING;
2112 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2114 GST_OBJECT_UNLOCK (element);
2116 return GST_STATE_CHANGE_FAILURE;
2121 * gst_element_get_state:
2122 * @element: a #GstElement to get the state of.
2123 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2125 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2126 * state. Can be %NULL.
2127 * @timeout: a #GstClockTime to specify the timeout for an async
2128 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2130 * Gets the state of the element.
2132 * For elements that performed an ASYNC state change, as reported by
2133 * gst_element_set_state(), this function will block up to the
2134 * specified timeout value for the state change to complete.
2135 * If the element completes the state change or goes into
2136 * an error, this function returns immediately with a return value of
2137 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2139 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2140 * returns the current and pending state immediately.
2142 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2143 * successfully changed its state but is not able to provide data yet.
2144 * This mostly happens for live sources that only produce data in
2145 * %GST_STATE_PLAYING. While the state change return is equivalent to
2146 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2147 * some sink elements might not be able to complete their state change because
2148 * an element is not producing data to complete the preroll. When setting the
2149 * element to playing, the preroll will complete and playback will start.
2151 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2152 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2153 * element is still performing a state change or
2154 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2158 GstStateChangeReturn
2159 gst_element_get_state (GstElement * element,
2160 GstState * state, GstState * pending, GstClockTime timeout)
2162 GstElementClass *oclass;
2163 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2165 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2167 oclass = GST_ELEMENT_GET_CLASS (element);
2169 if (oclass->get_state)
2170 result = (oclass->get_state) (element, state, pending, timeout);
2176 * gst_element_abort_state:
2177 * @element: a #GstElement to abort the state of.
2179 * Abort the state change of the element. This function is used
2180 * by elements that do asynchronous state changes and find out
2181 * something is wrong.
2183 * This function should be called with the STATE_LOCK held.
2188 gst_element_abort_state (GstElement * element)
2192 #ifndef GST_DISABLE_GST_DEBUG
2196 g_return_if_fail (GST_IS_ELEMENT (element));
2198 GST_OBJECT_LOCK (element);
2199 pending = GST_STATE_PENDING (element);
2201 if (pending == GST_STATE_VOID_PENDING ||
2202 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2203 goto nothing_aborted;
2205 #ifndef GST_DISABLE_GST_DEBUG
2206 old_state = GST_STATE (element);
2208 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2209 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2210 gst_element_state_get_name (pending));
2214 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2216 GST_STATE_BROADCAST (element);
2217 GST_OBJECT_UNLOCK (element);
2223 GST_OBJECT_UNLOCK (element);
2228 /* Not static because GstBin has manual state handling too */
2230 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2231 GstState newstate, GstState pending)
2233 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2234 GstMessage *message;
2236 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2237 "notifying about state-changed %s to %s (%s pending)",
2238 gst_element_state_get_name (oldstate),
2239 gst_element_state_get_name (newstate),
2240 gst_element_state_get_name (pending));
2242 if (klass->state_changed)
2243 klass->state_changed (element, oldstate, newstate, pending);
2245 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2246 oldstate, newstate, pending);
2247 gst_element_post_message (element, message);
2251 * gst_element_continue_state:
2252 * @element: a #GstElement to continue the state change of.
2253 * @ret: The previous state return value
2255 * Commit the state change of the element and proceed to the next
2256 * pending state if any. This function is used
2257 * by elements that do asynchronous state changes.
2258 * The core will normally call this method automatically when an
2259 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2261 * If after calling this method the element still has not reached
2262 * the pending state, the next state change is performed.
2264 * This method is used internally and should normally not be called by plugins
2267 * Returns: The result of the commit state change.
2271 GstStateChangeReturn
2272 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2274 GstStateChangeReturn old_ret;
2275 GstState old_state, old_next;
2276 GstState current, next, pending;
2277 GstStateChange transition;
2279 GST_OBJECT_LOCK (element);
2280 old_ret = GST_STATE_RETURN (element);
2281 GST_STATE_RETURN (element) = ret;
2282 pending = GST_STATE_PENDING (element);
2284 /* check if there is something to commit */
2285 if (pending == GST_STATE_VOID_PENDING)
2286 goto nothing_pending;
2288 old_state = GST_STATE (element);
2289 /* this is the state we should go to next */
2290 old_next = GST_STATE_NEXT (element);
2291 /* update current state */
2292 current = GST_STATE (element) = old_next;
2294 /* see if we reached the final state */
2295 if (pending == current)
2298 next = GST_STATE_GET_NEXT (current, pending);
2299 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2301 GST_STATE_NEXT (element) = next;
2303 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2304 GST_OBJECT_UNLOCK (element);
2306 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2307 "committing state from %s to %s, pending %s, next %s",
2308 gst_element_state_get_name (old_state),
2309 gst_element_state_get_name (old_next),
2310 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2312 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2314 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2315 "continue state change %s to %s, final %s",
2316 gst_element_state_get_name (current),
2317 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2319 ret = gst_element_change_state (element, transition);
2325 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2326 GST_OBJECT_UNLOCK (element);
2331 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2332 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2334 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2335 "completed state change to %s", gst_element_state_get_name (pending));
2336 GST_OBJECT_UNLOCK (element);
2338 /* don't post silly messages with the same state. This can happen
2339 * when an element state is changed to what it already was. For bins
2340 * this can be the result of a lost state, which we check with the
2341 * previous return value.
2342 * We do signal the cond though as a _get_state() might be blocking
2344 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2345 _priv_gst_element_state_changed (element, old_state, old_next,
2346 GST_STATE_VOID_PENDING);
2348 GST_STATE_BROADCAST (element);
2355 * gst_element_lost_state:
2356 * @element: a #GstElement the state is lost of
2357 * @new_base_time: if a new base time should be distributed
2359 * Brings the element to the lost state. The current state of the
2360 * element is copied to the pending state so that any call to
2361 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2363 * An ASYNC_START message is posted with indication to distribute a new
2364 * base_time to the element when @new_base_time is %TRUE.
2365 * If the element was PLAYING, it will go to PAUSED. The element
2366 * will be restored to its PLAYING state by the parent pipeline when it
2369 * This is mostly used for elements that lost their preroll buffer
2370 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2371 * they will go to their pending state again when a new preroll buffer is
2372 * queued. This function can only be called when the element is currently
2373 * not in error or an async state change.
2375 * This function is used internally and should normally not be called from
2376 * plugins or applications.
2379 gst_element_lost_state (GstElement * element, gboolean new_base_time)
2381 GstState old_state, new_state;
2382 GstMessage *message;
2384 g_return_if_fail (GST_IS_ELEMENT (element));
2386 GST_OBJECT_LOCK (element);
2387 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2390 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2391 goto only_async_start;
2393 old_state = GST_STATE (element);
2395 /* when we were PLAYING, the new state is PAUSED. We will also not
2396 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2397 * when we preroll. */
2398 if (old_state > GST_STATE_PAUSED)
2399 new_state = GST_STATE_PAUSED;
2401 new_state = old_state;
2403 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2404 "lost state of %s to %s", gst_element_state_get_name (old_state),
2405 gst_element_state_get_name (new_state));
2407 GST_STATE (element) = new_state;
2408 GST_STATE_NEXT (element) = new_state;
2409 GST_STATE_PENDING (element) = new_state;
2410 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2412 GST_ELEMENT_START_TIME (element) = 0;
2413 GST_OBJECT_UNLOCK (element);
2415 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2418 gst_message_new_async_start (GST_OBJECT_CAST (element), new_base_time);
2419 gst_element_post_message (element, message);
2425 GST_OBJECT_UNLOCK (element);
2430 GST_OBJECT_UNLOCK (element);
2432 message = gst_message_new_async_start (GST_OBJECT_CAST (element), TRUE);
2433 gst_element_post_message (element, message);
2439 * gst_element_set_state:
2440 * @element: a #GstElement to change state of.
2441 * @state: the element's new #GstState.
2443 * Sets the state of the element. This function will try to set the
2444 * requested state by going through all the intermediary states and calling
2445 * the class's state change function for each.
2447 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2448 * element will perform the remainder of the state change asynchronously in
2450 * An application can use gst_element_get_state() to wait for the completion
2451 * of the state change or it can wait for a state change message on the bus.
2453 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2454 * #GST_STATE_CHANGE_ASYNC.
2456 * Returns: Result of the state change using #GstStateChangeReturn.
2460 GstStateChangeReturn
2461 gst_element_set_state (GstElement * element, GstState state)
2463 GstElementClass *oclass;
2464 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2466 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2468 oclass = GST_ELEMENT_GET_CLASS (element);
2470 if (oclass->set_state)
2471 result = (oclass->set_state) (element, state);
2477 * default set state function, calculates the next state based
2478 * on current state and calls the change_state function
2480 static GstStateChangeReturn
2481 gst_element_set_state_func (GstElement * element, GstState state)
2483 GstState current, next, old_pending;
2484 GstStateChangeReturn ret;
2485 GstStateChange transition;
2486 GstStateChangeReturn old_ret;
2488 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2490 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2491 gst_element_state_get_name (state));
2493 /* state lock is taken to protect the set_state() and get_state()
2494 * procedures, it does not lock any variables. */
2495 GST_STATE_LOCK (element);
2497 /* now calculate how to get to the new state */
2498 GST_OBJECT_LOCK (element);
2499 old_ret = GST_STATE_RETURN (element);
2500 /* previous state change returned an error, remove all pending
2501 * and next states */
2502 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2503 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2504 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2505 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2508 current = GST_STATE (element);
2509 next = GST_STATE_NEXT (element);
2510 old_pending = GST_STATE_PENDING (element);
2512 /* this is the (new) state we should go to. TARGET is the last state we set on
2514 if (state != GST_STATE_TARGET (element)) {
2515 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2516 "setting target state to %s", gst_element_state_get_name (state));
2517 GST_STATE_TARGET (element) = state;
2518 /* increment state cookie so that we can track each state change. We only do
2519 * this if this is actually a new state change. */
2520 element->state_cookie++;
2522 GST_STATE_PENDING (element) = state;
2524 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2525 "current %s, old_pending %s, next %s, old return %s",
2526 gst_element_state_get_name (current),
2527 gst_element_state_get_name (old_pending),
2528 gst_element_state_get_name (next),
2529 gst_element_state_change_return_get_name (old_ret));
2531 /* if the element was busy doing a state change, we just update the
2532 * target state, it'll get to it async then. */
2533 if (old_pending != GST_STATE_VOID_PENDING) {
2534 /* upwards state change will happen ASYNC */
2535 if (old_pending <= state)
2537 /* element is going to this state already */
2538 else if (next == state)
2540 /* element was performing an ASYNC upward state change and
2541 * we request to go downward again. Start from the next pending
2543 else if (next > state
2544 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2548 next = GST_STATE_GET_NEXT (current, state);
2549 /* now we store the next state */
2550 GST_STATE_NEXT (element) = next;
2551 /* mark busy, we need to check that there is actually a state change
2552 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2553 * the default element change_state function has no way to know what the
2554 * old value was... could consider this a FIXME...*/
2555 if (current != next)
2556 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2558 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2560 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2561 "%s: setting state from %s to %s",
2562 (next != state ? "intermediate" : "final"),
2563 gst_element_state_get_name (current), gst_element_state_get_name (next));
2565 /* now signal any waiters, they will error since the cookie was incremented */
2566 GST_STATE_BROADCAST (element);
2568 GST_OBJECT_UNLOCK (element);
2570 ret = gst_element_change_state (element, transition);
2572 GST_STATE_UNLOCK (element);
2574 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2575 gst_element_state_change_return_get_name (ret));
2581 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2582 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2583 "element was busy with async state change");
2584 GST_OBJECT_UNLOCK (element);
2586 GST_STATE_UNLOCK (element);
2588 return GST_STATE_CHANGE_ASYNC;
2593 * gst_element_change_state:
2594 * @element: a #GstElement
2595 * @transition: the requested transition
2597 * Perform @transition on @element.
2599 * This function must be called with STATE_LOCK held and is mainly used
2602 * Returns: the #GstStateChangeReturn of the state transition.
2604 GstStateChangeReturn
2605 gst_element_change_state (GstElement * element, GstStateChange transition)
2607 GstElementClass *oclass;
2608 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2610 oclass = GST_ELEMENT_GET_CLASS (element);
2612 /* call the state change function so it can set the state */
2613 if (oclass->change_state)
2614 ret = (oclass->change_state) (element, transition);
2616 ret = GST_STATE_CHANGE_FAILURE;
2619 case GST_STATE_CHANGE_FAILURE:
2620 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2621 "have FAILURE change_state return");
2622 /* state change failure */
2623 gst_element_abort_state (element);
2625 case GST_STATE_CHANGE_ASYNC:
2629 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2630 "element will change state ASYNC");
2632 target = GST_STATE_TARGET (element);
2634 if (target > GST_STATE_READY)
2637 /* else we just continue the state change downwards */
2638 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2639 "forcing commit state %s <= %s",
2640 gst_element_state_get_name (target),
2641 gst_element_state_get_name (GST_STATE_READY));
2643 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2646 case GST_STATE_CHANGE_SUCCESS:
2647 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2648 "element changed state SUCCESS");
2649 /* we can commit the state now which will proceeed to
2651 ret = gst_element_continue_state (element, ret);
2653 case GST_STATE_CHANGE_NO_PREROLL:
2654 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2655 "element changed state NO_PREROLL");
2656 /* we can commit the state now which will proceeed to
2658 ret = gst_element_continue_state (element, ret);
2661 goto invalid_return;
2664 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2669 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2677 GST_OBJECT_LOCK (element);
2678 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2679 g_critical ("%s: unknown return value %d from a state change function",
2680 GST_ELEMENT_NAME (element), ret);
2682 /* we are in error now */
2683 ret = GST_STATE_CHANGE_FAILURE;
2684 GST_STATE_RETURN (element) = ret;
2685 GST_OBJECT_UNLOCK (element);
2691 /* gst_iterator_fold functions for pads_activate
2692 * Stop the iterator if activating one pad failed. */
2694 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2696 GstPad *pad = g_value_get_object (vpad);
2697 gboolean cont = TRUE;
2699 if (!(cont = gst_pad_set_active (pad, *active)))
2700 g_value_set_boolean (ret, FALSE);
2705 /* returns false on error or early cutout of the fold, true if all
2706 * pads in @iter were (de)activated successfully. */
2708 iterator_activate_fold_with_resync (GstIterator * iter,
2709 GstIteratorFoldFunction func, gpointer user_data)
2711 GstIteratorResult ires;
2714 /* no need to unset this later, it's just a boolean */
2715 g_value_init (&ret, G_TYPE_BOOLEAN);
2716 g_value_set_boolean (&ret, TRUE);
2719 ires = gst_iterator_fold (iter, func, &ret, user_data);
2721 case GST_ITERATOR_RESYNC:
2722 /* need to reset the result again */
2723 g_value_set_boolean (&ret, TRUE);
2724 gst_iterator_resync (iter);
2726 case GST_ITERATOR_DONE:
2727 /* all pads iterated, return collected value */
2730 /* iterator returned _ERROR or premature end with _OK,
2731 * mark an error and exit */
2732 g_value_set_boolean (&ret, FALSE);
2737 /* return collected value */
2738 return g_value_get_boolean (&ret);
2741 /* is called with STATE_LOCK
2743 * Pads are activated from source pads to sinkpads.
2746 gst_element_pads_activate (GstElement * element, gboolean active)
2751 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2752 "pads_activate with active %d", active);
2754 iter = gst_element_iterate_src_pads (element);
2756 iterator_activate_fold_with_resync (iter,
2757 (GstIteratorFoldFunction) activate_pads, &active);
2758 gst_iterator_free (iter);
2759 if (G_UNLIKELY (!res))
2762 iter = gst_element_iterate_sink_pads (element);
2764 iterator_activate_fold_with_resync (iter,
2765 (GstIteratorFoldFunction) activate_pads, &active);
2766 gst_iterator_free (iter);
2767 if (G_UNLIKELY (!res))
2770 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2771 "pads_activate successful");
2778 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2779 "source pads_activate failed");
2784 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2785 "sink pads_activate failed");
2790 /* is called with STATE_LOCK */
2791 static GstStateChangeReturn
2792 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2794 GstState state, next;
2795 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2797 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2799 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2800 next = GST_STATE_TRANSITION_NEXT (transition);
2802 /* if the element already is in the given state, we just return success */
2803 if (next == GST_STATE_VOID_PENDING || state == next)
2806 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2807 "default handler tries setting state from %s to %s (%04x)",
2808 gst_element_state_get_name (state),
2809 gst_element_state_get_name (next), transition);
2811 switch (transition) {
2812 case GST_STATE_CHANGE_NULL_TO_READY:
2814 case GST_STATE_CHANGE_READY_TO_PAUSED:
2815 if (!gst_element_pads_activate (element, TRUE)) {
2816 result = GST_STATE_CHANGE_FAILURE;
2819 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2821 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2823 case GST_STATE_CHANGE_PAUSED_TO_READY:
2824 case GST_STATE_CHANGE_READY_TO_NULL:
2825 /* deactivate pads in both cases, since they are activated on
2826 ready->paused but the element might not have made it to paused */
2827 if (!gst_element_pads_activate (element, FALSE)) {
2828 result = GST_STATE_CHANGE_FAILURE;
2832 /* this will catch real but unhandled state changes;
2833 * can only be caused by:
2834 * - a new state was added
2835 * - somehow the element was asked to jump across an intermediate state
2837 g_warning ("Unhandled state change from %s to %s",
2838 gst_element_state_get_name (state),
2839 gst_element_state_get_name (next));
2846 GST_OBJECT_LOCK (element);
2847 result = GST_STATE_RETURN (element);
2848 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2849 "element is already in the %s state",
2850 gst_element_state_get_name (state));
2851 GST_OBJECT_UNLOCK (element);
2858 * gst_element_get_factory:
2859 * @element: a #GstElement to request the element factory of.
2861 * Retrieves the factory that was used to create this element.
2863 * Returns: (transfer none): the #GstElementFactory used for creating this
2864 * element. no refcounting is needed.
2867 gst_element_get_factory (GstElement * element)
2869 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2871 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2875 gst_element_dispose (GObject * object)
2877 GstElement *element = GST_ELEMENT_CAST (object);
2881 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2883 if (GST_STATE (element) != GST_STATE_NULL)
2886 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2887 "removing %d pads", g_list_length (element->pads));
2888 /* first we break all our links with the outside */
2889 while (element->pads && element->pads->data) {
2890 /* don't call _remove_pad with NULL */
2891 gst_element_remove_pad (element, GST_PAD_CAST (element->pads->data));
2893 if (G_UNLIKELY (element->pads != NULL)) {
2894 g_critical ("could not remove pads from element %s",
2895 GST_STR_NULL (GST_OBJECT_NAME (object)));
2898 GST_OBJECT_LOCK (element);
2899 clock_p = &element->clock;
2900 bus_p = &element->bus;
2901 gst_object_replace ((GstObject **) clock_p, NULL);
2902 gst_object_replace ((GstObject **) bus_p, NULL);
2903 GST_OBJECT_UNLOCK (element);
2905 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2907 G_OBJECT_CLASS (parent_class)->dispose (object);
2916 is_locked = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
2918 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2920 "You need to explicitly set elements to the NULL state before\n"
2921 "dropping the final reference, to allow them to clean up.\n"
2922 "This problem may also be caused by a refcounting bug in the\n"
2923 "application or some element.\n",
2924 GST_OBJECT_NAME (element),
2925 gst_element_state_get_name (GST_STATE (element)),
2926 is_locked ? " (locked)" : "");
2932 gst_element_finalize (GObject * object)
2934 GstElement *element = GST_ELEMENT_CAST (object);
2936 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2938 GST_STATE_LOCK (element);
2939 if (element->state_cond)
2940 g_cond_free (element->state_cond);
2941 element->state_cond = NULL;
2942 GST_STATE_UNLOCK (element);
2943 g_static_rec_mutex_free (element->state_lock);
2944 g_slice_free (GStaticRecMutex, element->state_lock);
2945 element->state_lock = NULL;
2947 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2949 G_OBJECT_CLASS (parent_class)->finalize (object);
2953 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2957 g_return_if_fail (GST_IS_ELEMENT (element));
2959 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2961 GST_OBJECT_LOCK (element);
2962 bus_p = &GST_ELEMENT_BUS (element);
2963 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
2964 GST_OBJECT_UNLOCK (element);
2968 * gst_element_set_bus:
2969 * @element: a #GstElement to set the bus of.
2970 * @bus: (transfer none): the #GstBus to set.
2972 * Sets the bus of the element. Increases the refcount on the bus.
2973 * For internal use only, unless you're testing elements.
2978 gst_element_set_bus (GstElement * element, GstBus * bus)
2980 GstElementClass *oclass;
2982 g_return_if_fail (GST_IS_ELEMENT (element));
2984 oclass = GST_ELEMENT_GET_CLASS (element);
2986 if (oclass->set_bus)
2987 oclass->set_bus (element, bus);
2991 * gst_element_get_bus:
2992 * @element: a #GstElement to get the bus of.
2994 * Returns the bus of the element. Note that only a #GstPipeline will provide a
2995 * bus for the application.
2997 * Returns: (transfer full): the element's #GstBus. unref after usage.
3002 gst_element_get_bus (GstElement * element)
3004 GstBus *result = NULL;
3006 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3008 GST_OBJECT_LOCK (element);
3009 if ((result = GST_ELEMENT_BUS (element)))
3010 gst_object_ref (result);
3011 GST_OBJECT_UNLOCK (element);
3013 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,