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 * An existing pad of an element can be retrieved by name with
45 * gst_element_get_static_pad(). A new dynamic pad can be created using
46 * gst_element_request_pad() with a #GstPadTemplate or
47 * gst_element_get_request_pad() with the template name such as "src_\%d".
48 * An iterator of all pads can be retrieved with gst_element_iterate_pads().
50 * Elements can be linked through their pads.
51 * If the link is straightforward, use the gst_element_link()
52 * convenience function to link two elements, or gst_element_link_many()
53 * for more elements in a row.
54 * Use gst_element_link_filtered() to link two elements constrained by
55 * a specified set of #GstCaps.
56 * For finer control, use gst_element_link_pads() and
57 * gst_element_link_pads_filtered() to specify the pads to link on
58 * each element by name.
60 * Each element has a state (see #GstState). You can get and set the state
61 * of an element with gst_element_get_state() and gst_element_set_state().
62 * Setting a state triggers a #GstStateChange. To get a string representation
63 * of a #GstState, use gst_element_state_get_name().
65 * You can get and set a #GstClock on an element using gst_element_get_clock()
66 * and gst_element_set_clock().
67 * Some elements can provide a clock for the pipeline if
68 * gst_element_provides_clock() returns %TRUE. With the
69 * gst_element_provide_clock() method one can retrieve the clock provided by
71 * Not all elements require a clock to operate correctly. If
72 * gst_element_requires_clock() returns %TRUE, a clock should be set on the
73 * element with gst_element_set_clock().
75 * Note that clock slection and distribution is normally handled by the
76 * toplevel #GstPipeline so the clock functions are only to be used in very
77 * specific situations.
79 * Last reviewed on 2009-05-29 (0.10.24)
82 #include "gst_private.h"
85 #include <gobject/gvaluecollector.h>
87 #include "gstelement.h"
88 #include "gstelementmetadata.h"
89 #include "gstenumtypes.h"
91 #include "gstmarshal.h"
97 #include "gst-i18n-lib.h"
99 /* Element signals and args */
115 static void gst_element_class_init (GstElementClass * klass);
116 static void gst_element_init (GstElement * element);
117 static void gst_element_base_class_init (gpointer g_class);
118 static void gst_element_base_class_finalize (gpointer g_class);
120 static void gst_element_dispose (GObject * object);
121 static void gst_element_finalize (GObject * object);
123 static GstStateChangeReturn gst_element_change_state_func (GstElement * element,
124 GstStateChange transition);
125 static GstStateChangeReturn gst_element_get_state_func (GstElement * element,
126 GstState * state, GstState * pending, GstClockTime timeout);
127 static GstStateChangeReturn gst_element_set_state_func (GstElement * element,
129 static void gst_element_set_bus_func (GstElement * element, GstBus * bus);
131 static gboolean gst_element_default_send_event (GstElement * element,
133 static gboolean gst_element_default_query (GstElement * element,
136 static GstPadTemplate
137 * gst_element_class_get_request_pad_template (GstElementClass *
138 element_class, const gchar * name);
140 static GstObjectClass *parent_class = NULL;
141 static guint gst_element_signals[LAST_SIGNAL] = { 0 };
143 /* this is used in gstelementfactory.c:gst_element_register() */
144 GQuark __gst_elementclass_factory = 0;
147 gst_element_get_type (void)
149 static volatile gsize gst_element_type = 0;
151 if (g_once_init_enter (&gst_element_type)) {
153 static const GTypeInfo element_info = {
154 sizeof (GstElementClass),
155 gst_element_base_class_init,
156 gst_element_base_class_finalize,
157 (GClassInitFunc) gst_element_class_init,
162 (GInstanceInitFunc) gst_element_init,
166 _type = g_type_register_static (GST_TYPE_OBJECT, "GstElement",
167 &element_info, G_TYPE_FLAG_ABSTRACT);
169 __gst_elementclass_factory =
170 g_quark_from_static_string ("GST_ELEMENTCLASS_FACTORY");
171 g_once_init_leave (&gst_element_type, _type);
173 return gst_element_type;
177 gst_element_class_init (GstElementClass * klass)
179 GObjectClass *gobject_class;
181 gobject_class = (GObjectClass *) klass;
183 parent_class = g_type_class_peek_parent (klass);
186 * GstElement::pad-added:
187 * @gstelement: the object which received the signal
188 * @new_pad: the pad that has been added
190 * a new #GstPad has been added to the element. Note that this signal will
191 * usually be emitted from the context of the streaming thread. Also keep in
192 * mind that if you add new elements to the pipeline in the signal handler
193 * you will need to set them to the desired target state with
194 * gst_element_set_state() or gst_element_sync_state_with_parent().
196 gst_element_signals[PAD_ADDED] =
197 g_signal_new ("pad-added", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
198 G_STRUCT_OFFSET (GstElementClass, pad_added), NULL, NULL,
199 gst_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GST_TYPE_PAD);
201 * GstElement::pad-removed:
202 * @gstelement: the object which received the signal
203 * @old_pad: the pad that has been removed
205 * a #GstPad has been removed from the element
207 gst_element_signals[PAD_REMOVED] =
208 g_signal_new ("pad-removed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
209 G_STRUCT_OFFSET (GstElementClass, pad_removed), NULL, NULL,
210 gst_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GST_TYPE_PAD);
212 * GstElement::no-more-pads:
213 * @gstelement: the object which received the signal
215 * This signals that the element will not generate more dynamic pads.
216 * Note that this signal will usually be emitted from the context of
217 * the streaming thread.
219 gst_element_signals[NO_MORE_PADS] =
220 g_signal_new ("no-more-pads", G_TYPE_FROM_CLASS (klass),
221 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstElementClass, no_more_pads), NULL,
222 NULL, gst_marshal_VOID__VOID, G_TYPE_NONE, 0);
224 gobject_class->dispose = gst_element_dispose;
225 gobject_class->finalize = gst_element_finalize;
227 klass->change_state = GST_DEBUG_FUNCPTR (gst_element_change_state_func);
228 klass->set_state = GST_DEBUG_FUNCPTR (gst_element_set_state_func);
229 klass->get_state = GST_DEBUG_FUNCPTR (gst_element_get_state_func);
230 klass->set_bus = GST_DEBUG_FUNCPTR (gst_element_set_bus_func);
231 klass->query = GST_DEBUG_FUNCPTR (gst_element_default_query);
232 klass->send_event = GST_DEBUG_FUNCPTR (gst_element_default_send_event);
233 klass->numpadtemplates = 0;
235 klass->elementfactory = NULL;
239 gst_element_base_class_init (gpointer g_class)
241 GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
242 GList *node, *padtemplates;
244 /* Copy the element details here so elements can inherit the
245 * details from their base class and classes only need to set
246 * the details in class_init instead of base_init */
247 element_class->metadata =
248 element_class->metadata ? gst_structure_copy (element_class->metadata) :
249 gst_structure_new_empty ("metadata");
251 /* Copy the pad templates so elements inherit them
252 * from their base class but elements can add pad templates in class_init
253 * instead of base_init.
255 padtemplates = g_list_copy (element_class->padtemplates);
256 for (node = padtemplates; node != NULL; node = node->next) {
257 GstPadTemplate *tmpl = (GstPadTemplate *) node->data;
258 gst_object_ref (tmpl);
260 element_class->padtemplates = padtemplates;
262 /* set the factory, see gst_element_register() */
263 element_class->elementfactory =
264 g_type_get_qdata (G_TYPE_FROM_CLASS (element_class),
265 __gst_elementclass_factory);
266 GST_DEBUG ("type %s : factory %p", G_OBJECT_CLASS_NAME (element_class),
267 element_class->elementfactory);
271 gst_element_base_class_finalize (gpointer g_class)
273 GstElementClass *klass = GST_ELEMENT_CLASS (g_class);
275 g_list_foreach (klass->padtemplates, (GFunc) gst_object_unref, NULL);
276 g_list_free (klass->padtemplates);
278 gst_structure_free (klass->metadata);
282 gst_element_init (GstElement * element)
284 GST_STATE (element) = GST_STATE_NULL;
285 GST_STATE_TARGET (element) = GST_STATE_NULL;
286 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
287 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
288 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
290 g_static_rec_mutex_init (&element->state_lock);
291 element->state_cond = g_cond_new ();
295 * gst_element_release_request_pad:
296 * @element: a #GstElement to release the request pad of.
297 * @pad: the #GstPad to release.
299 * Makes the element free the previously requested pad as obtained
300 * with gst_element_get_request_pad().
302 * This does not unref the pad. If the pad was created by using
303 * gst_element_get_request_pad(), gst_element_release_request_pad() needs to be
304 * followed by gst_object_unref() to free the @pad.
309 gst_element_release_request_pad (GstElement * element, GstPad * pad)
311 GstElementClass *oclass;
313 g_return_if_fail (GST_IS_ELEMENT (element));
314 g_return_if_fail (GST_IS_PAD (pad));
316 oclass = GST_ELEMENT_GET_CLASS (element);
318 /* if the element implements a custom release function we call that, else we
319 * simply remove the pad from the element */
320 if (oclass->release_pad)
321 (oclass->release_pad) (element, pad);
323 gst_element_remove_pad (element, pad);
327 * gst_element_requires_clock:
328 * @element: a #GstElement to query
330 * Query if the element requires a clock.
332 * Returns: %TRUE if the element requires a clock
337 gst_element_requires_clock (GstElement * element)
341 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
343 result = (GST_ELEMENT_GET_CLASS (element)->set_clock != NULL);
349 * gst_element_provides_clock:
350 * @element: a #GstElement to query
352 * Query if the element provides a clock. A #GstClock provided by an
353 * element can be used as the global #GstClock for the pipeline.
354 * An element that can provide a clock is only required to do so in the PAUSED
355 * state, this means when it is fully negotiated and has allocated the resources
356 * to operate the clock.
358 * Returns: %TRUE if the element provides a clock
363 gst_element_provides_clock (GstElement * element)
367 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
369 result = (GST_ELEMENT_GET_CLASS (element)->provide_clock != NULL);
375 * gst_element_provide_clock:
376 * @element: a #GstElement to query
378 * Get the clock provided by the given element.
379 * <note>An element is only required to provide a clock in the PAUSED
380 * state. Some elements can provide a clock in other states.</note>
382 * Returns: (transfer full): the GstClock provided by the element or %NULL
383 * if no clock could be provided. Unref after usage.
388 gst_element_provide_clock (GstElement * element)
390 GstClock *result = NULL;
391 GstElementClass *oclass;
393 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
395 oclass = GST_ELEMENT_GET_CLASS (element);
397 if (oclass->provide_clock)
398 result = oclass->provide_clock (element);
404 * gst_element_set_clock:
405 * @element: a #GstElement to set the clock for.
406 * @clock: the #GstClock to set for the element.
408 * Sets the clock for the element. This function increases the
409 * refcount on the clock. Any previously set clock on the object
412 * Returns: %TRUE if the element accepted the clock. An element can refuse a
413 * clock when it, for example, is not able to slave its internal clock to the
414 * @clock or when it requires a specific clock to operate.
419 gst_element_set_clock (GstElement * element, GstClock * clock)
421 GstElementClass *oclass;
425 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
426 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
428 oclass = GST_ELEMENT_GET_CLASS (element);
430 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
432 if (oclass->set_clock)
433 res = oclass->set_clock (element, clock);
436 /* only update the clock pointer if the element accepted the clock */
437 GST_OBJECT_LOCK (element);
438 clock_p = &element->clock;
439 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
440 GST_OBJECT_UNLOCK (element);
446 * gst_element_get_clock:
447 * @element: a #GstElement to get the clock of.
449 * Gets the currently configured clock of the element. This is the clock as was
450 * last set with gst_element_set_clock().
452 * Returns: (transfer full): the #GstClock of the element. unref after usage.
457 gst_element_get_clock (GstElement * element)
461 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
463 GST_OBJECT_LOCK (element);
464 if ((result = element->clock))
465 gst_object_ref (result);
466 GST_OBJECT_UNLOCK (element);
472 * gst_element_set_base_time:
473 * @element: a #GstElement.
474 * @time: the base time to set.
476 * Set the base time of an element. See gst_element_get_base_time().
481 gst_element_set_base_time (GstElement * element, GstClockTime time)
485 g_return_if_fail (GST_IS_ELEMENT (element));
487 GST_OBJECT_LOCK (element);
488 old = element->base_time;
489 element->base_time = time;
490 GST_OBJECT_UNLOCK (element);
492 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
493 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
494 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
498 * gst_element_get_base_time:
499 * @element: a #GstElement.
501 * Returns the base time of the element. The base time is the
502 * absolute time of the clock when this element was last put to
503 * PLAYING. Subtracting the base time from the clock time gives
504 * the running time of the element.
506 * Returns: the base time of the element.
511 gst_element_get_base_time (GstElement * element)
515 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
517 GST_OBJECT_LOCK (element);
518 result = element->base_time;
519 GST_OBJECT_UNLOCK (element);
525 * gst_element_set_start_time:
526 * @element: a #GstElement.
527 * @time: the base time to set.
529 * Set the start time of an element. The start time of the element is the
530 * running time of the element when it last went to the PAUSED state. In READY
531 * or after a flushing seek, it is set to 0.
533 * Toplevel elements like #GstPipeline will manage the start_time and
534 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
535 * on such a toplevel element will disable the distribution of the base_time to
536 * the children and can be useful if the application manages the base_time
537 * itself, for example if you want to synchronize capture from multiple
538 * pipelines, and you can also ensure that the pipelines have the same clock.
545 gst_element_set_start_time (GstElement * element, GstClockTime time)
549 g_return_if_fail (GST_IS_ELEMENT (element));
551 GST_OBJECT_LOCK (element);
552 old = GST_ELEMENT_START_TIME (element);
553 GST_ELEMENT_START_TIME (element) = time;
554 GST_OBJECT_UNLOCK (element);
556 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
557 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
558 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
562 * gst_element_get_start_time:
563 * @element: a #GstElement.
565 * Returns the start time of the element. The start time is the
566 * running time of the clock when this element was last put to PAUSED.
568 * Usually the start_time is managed by a toplevel element such as
573 * Returns: the start time of the element.
578 gst_element_get_start_time (GstElement * element)
582 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
584 GST_OBJECT_LOCK (element);
585 result = GST_ELEMENT_START_TIME (element);
586 GST_OBJECT_UNLOCK (element);
592 * gst_element_is_indexable:
593 * @element: a #GstElement.
595 * Queries if the element can be indexed.
597 * Returns: TRUE if the element can be indexed.
602 gst_element_is_indexable (GstElement * element)
606 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
608 result = (GST_ELEMENT_GET_CLASS (element)->set_index != NULL);
614 * gst_element_set_index:
615 * @element: a #GstElement.
616 * @index: (transfer none): a #GstIndex.
618 * Set @index on the element. The refcount of the index
619 * will be increased, any previously set index is unreffed.
624 gst_element_set_index (GstElement * element, GstIndex * index)
626 GstElementClass *oclass;
628 g_return_if_fail (GST_IS_ELEMENT (element));
629 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
631 oclass = GST_ELEMENT_GET_CLASS (element);
633 if (oclass->set_index)
634 oclass->set_index (element, index);
638 * gst_element_get_index:
639 * @element: a #GstElement.
641 * Gets the index from the element.
643 * Returns: (transfer full): a #GstIndex or %NULL when no index was set on the
644 * element. unref after usage.
649 gst_element_get_index (GstElement * element)
651 GstElementClass *oclass;
652 GstIndex *result = NULL;
654 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
656 oclass = GST_ELEMENT_GET_CLASS (element);
658 if (oclass->get_index)
659 result = oclass->get_index (element);
665 * gst_element_add_pad:
666 * @element: a #GstElement to add the pad to.
667 * @pad: (transfer full): the #GstPad to add to the element.
669 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
670 * see gst_object_set_parent() for refcounting information.
672 * Pads are not automatically activated so elements should perform the needed
673 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
674 * state. See gst_pad_set_active() for more information about activating pads.
676 * The pad and the element should be unlocked when calling this function.
678 * This function will emit the #GstElement::pad-added signal on the element.
680 * Returns: %TRUE if the pad could be added. This function can fail when
681 * a pad with the same name already existed or the pad already had another
687 gst_element_add_pad (GstElement * element, GstPad * pad)
692 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
693 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
695 /* locking pad to look at the name */
696 GST_OBJECT_LOCK (pad);
697 pad_name = g_strdup (GST_PAD_NAME (pad));
698 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
699 GST_STR_NULL (pad_name));
700 flushing = GST_PAD_IS_FLUSHING (pad);
701 GST_OBJECT_UNLOCK (pad);
703 /* then check to see if there's already a pad by that name here */
704 GST_OBJECT_LOCK (element);
705 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
708 /* try to set the pad's parent */
709 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
710 GST_OBJECT_CAST (element))))
713 /* check for flushing pads */
714 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
715 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
716 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
717 "use gst_pad_set_active(pad,TRUE) before adding it.",
718 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
720 GST_OBJECT_LOCK (pad);
721 GST_PAD_UNSET_FLUSHING (pad);
722 GST_OBJECT_UNLOCK (pad);
727 /* add it to the list */
728 switch (gst_pad_get_direction (pad)) {
730 element->srcpads = g_list_prepend (element->srcpads, pad);
731 element->numsrcpads++;
734 element->sinkpads = g_list_prepend (element->sinkpads, pad);
735 element->numsinkpads++;
740 element->pads = g_list_prepend (element->pads, pad);
742 element->pads_cookie++;
743 GST_OBJECT_UNLOCK (element);
745 /* emit the PAD_ADDED signal */
746 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
753 g_critical ("Padname %s is not unique in element %s, not adding",
754 pad_name, GST_ELEMENT_NAME (element));
755 GST_OBJECT_UNLOCK (element);
762 ("Pad %s already has parent when trying to add to element %s",
763 pad_name, GST_ELEMENT_NAME (element));
764 GST_OBJECT_UNLOCK (element);
770 GST_OBJECT_LOCK (pad);
772 ("Trying to add pad %s to element %s, but it has no direction",
773 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
774 GST_OBJECT_UNLOCK (pad);
775 GST_OBJECT_UNLOCK (element);
781 * gst_element_remove_pad:
782 * @element: a #GstElement to remove pad from.
783 * @pad: (transfer none): the #GstPad to remove from the element.
785 * Removes @pad from @element. @pad will be destroyed if it has not been
786 * referenced elsewhere using gst_object_unparent().
788 * This function is used by plugin developers and should not be used
789 * by applications. Pads that were dynamically requested from elements
790 * with gst_element_get_request_pad() should be released with the
791 * gst_element_release_request_pad() function instead.
793 * Pads are not automatically deactivated so elements should perform the needed
794 * steps to deactivate the pad in case this pad is removed in the PAUSED or
795 * PLAYING state. See gst_pad_set_active() for more information about
798 * The pad and the element should be unlocked when calling this function.
800 * This function will emit the #GstElement::pad-removed signal on the element.
802 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
803 * pad does not belong to the provided element.
808 gst_element_remove_pad (GstElement * element, GstPad * pad)
812 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
813 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
815 /* locking pad to look at the name and parent */
816 GST_OBJECT_LOCK (pad);
817 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
818 GST_STR_NULL (GST_PAD_NAME (pad)));
820 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
822 GST_OBJECT_UNLOCK (pad);
825 if ((peer = gst_pad_get_peer (pad))) {
826 /* window for MT unsafeness, someone else could unlink here
827 * and then we call unlink with wrong pads. The unlink
828 * function would catch this and safely return failed. */
829 if (GST_PAD_IS_SRC (pad))
830 gst_pad_unlink (pad, peer);
832 gst_pad_unlink (peer, pad);
834 gst_object_unref (peer);
837 GST_OBJECT_LOCK (element);
838 /* remove it from the list */
839 switch (gst_pad_get_direction (pad)) {
841 element->srcpads = g_list_remove (element->srcpads, pad);
842 element->numsrcpads--;
845 element->sinkpads = g_list_remove (element->sinkpads, pad);
846 element->numsinkpads--;
849 g_critical ("Removing pad without direction???");
852 element->pads = g_list_remove (element->pads, pad);
854 element->pads_cookie++;
855 GST_OBJECT_UNLOCK (element);
857 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
858 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
860 gst_object_unparent (GST_OBJECT_CAST (pad));
867 /* locking order is element > pad */
868 GST_OBJECT_UNLOCK (pad);
870 GST_OBJECT_LOCK (element);
871 GST_OBJECT_LOCK (pad);
872 g_critical ("Padname %s:%s does not belong to element %s when removing",
873 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
874 GST_OBJECT_UNLOCK (pad);
875 GST_OBJECT_UNLOCK (element);
881 * gst_element_no_more_pads:
882 * @element: a #GstElement
884 * Use this function to signal that the element does not expect any more pads
885 * to show up in the current pipeline. This function should be called whenever
886 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
887 * pad templates use this in combination with autopluggers to figure out that
888 * the element is done initializing its pads.
890 * This function emits the #GstElement::no-more-pads signal.
895 gst_element_no_more_pads (GstElement * element)
897 g_return_if_fail (GST_IS_ELEMENT (element));
899 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
903 pad_compare_name (GstPad * pad1, const gchar * name)
907 GST_OBJECT_LOCK (pad1);
908 result = strcmp (GST_PAD_NAME (pad1), name);
909 GST_OBJECT_UNLOCK (pad1);
915 * gst_element_get_static_pad:
916 * @element: a #GstElement to find a static pad of.
917 * @name: the name of the static #GstPad to retrieve.
919 * Retrieves a pad from @element by name. This version only retrieves
920 * already-existing (i.e. 'static') pads.
922 * Returns: (transfer full): the requested #GstPad if found, otherwise %NULL.
928 gst_element_get_static_pad (GstElement * element, const gchar * name)
931 GstPad *result = NULL;
933 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
934 g_return_val_if_fail (name != NULL, NULL);
936 GST_OBJECT_LOCK (element);
938 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
940 result = GST_PAD_CAST (find->data);
941 gst_object_ref (result);
944 if (result == NULL) {
945 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
946 name, GST_ELEMENT_NAME (element));
948 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
949 GST_ELEMENT_NAME (element), name);
951 GST_OBJECT_UNLOCK (element);
957 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
958 const gchar * name, const GstCaps * caps)
960 GstPad *newpad = NULL;
961 GstElementClass *oclass;
963 oclass = GST_ELEMENT_GET_CLASS (element);
965 #ifndef G_DISABLE_CHECKS
966 /* Some sanity checking here */
970 /* Is this the template name? */
971 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
972 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
974 const gchar *str, *data;
977 /* Otherwise check if it's a valid name for the name template */
978 str = strchr (templ->name_template, '%');
979 g_return_val_if_fail (str != NULL, NULL);
980 g_return_val_if_fail (strncmp (templ->name_template, name,
981 str - templ->name_template) == 0, NULL);
982 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
984 data = name + (str - templ->name_template);
986 /* Can either be %s or %d or %u, do sanity checking for %d */
987 if (*(str + 1) == 'd') {
991 tmp = g_ascii_strtoll (data, &endptr, 10);
992 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
993 && *endptr == '\0', NULL);
994 } else if (*(str + 1) == 'u') {
998 tmp = g_ascii_strtoull (data, &endptr, 10);
999 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
1003 pad = gst_element_get_static_pad (element, name);
1005 gst_object_unref (pad);
1006 /* FIXME 0.11: Change this to g_return_val_if_fail() */
1007 g_critical ("Element %s already has a pad named %s, the behaviour of "
1008 " gst_element_get_request_pad() for existing pads is undefined!",
1009 GST_ELEMENT_NAME (element), name);
1014 if (oclass->request_new_pad)
1015 newpad = (oclass->request_new_pad) (element, templ, name, caps);
1018 gst_object_ref (newpad);
1024 * gst_element_get_request_pad:
1025 * @element: a #GstElement to find a request pad of.
1026 * @name: the name of the request #GstPad to retrieve.
1028 * Retrieves a pad from the element by name (e.g. "src_\%d"). This version only
1029 * retrieves request pads. The pad should be released with
1030 * gst_element_release_request_pad().
1032 * This method is slow and will be deprecated in the future. New code should
1033 * use gst_element_request_pad() with the requested template.
1035 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1036 * Release after usage.
1039 gst_element_get_request_pad (GstElement * element, const gchar * name)
1041 GstPadTemplate *templ = NULL;
1043 const gchar *req_name = NULL;
1044 gboolean templ_found = FALSE;
1047 gchar *str, *endptr = NULL;
1048 GstElementClass *class;
1050 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1051 g_return_val_if_fail (name != NULL, NULL);
1053 class = GST_ELEMENT_GET_CLASS (element);
1055 /* if the name contains a %, we assume it's the complete template name. Get
1056 * the template and try to get a pad */
1057 if (strstr (name, "%")) {
1058 templ = gst_element_class_get_request_pad_template (class, name);
1063 /* there is no % in the name, try to find a matching template */
1064 list = class->padtemplates;
1065 while (!templ_found && list) {
1066 templ = (GstPadTemplate *) list->data;
1067 if (templ->presence == GST_PAD_REQUEST) {
1068 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1069 templ->name_template);
1070 /* see if we find an exact match */
1071 if (strcmp (name, templ->name_template) == 0) {
1076 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1077 and %d and %u, occurring at the end of the name_template, are the only
1079 else if ((str = strchr (templ->name_template, '%'))
1080 && strncmp (templ->name_template, name,
1081 str - templ->name_template) == 0
1082 && strlen (name) > str - templ->name_template) {
1083 data = name + (str - templ->name_template);
1084 if (*(str + 1) == 'd') {
1088 tmp = strtol (data, &endptr, 10);
1089 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1095 } else if (*(str + 1) == 'u') {
1099 tmp = strtoul (data, &endptr, 10);
1100 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1120 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1126 * gst_element_request_pad:
1127 * @element: a #GstElement to find a request pad of.
1128 * @templ: a #GstPadTemplate of which we want a pad of.
1129 * @name: (transfer none) (allow-none): the name of the request #GstPad
1130 * to retrieve. Can be %NULL.
1131 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1132 * request. Can be %NULL.
1134 * Retrieves a request pad from the element according to the provided template.
1135 * Pad templates can be looked up using
1136 * gst_element_factory_get_static_pad_templates().
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);
1155 static GstIterator *
1156 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1158 GstIterator *result;
1160 GST_OBJECT_LOCK (element);
1161 result = gst_iterator_new_list (GST_TYPE_PAD,
1162 GST_OBJECT_GET_LOCK (element),
1163 &element->pads_cookie, padlist, (GObject *) element, NULL);
1164 GST_OBJECT_UNLOCK (element);
1170 * gst_element_iterate_pads:
1171 * @element: a #GstElement to iterate pads of.
1173 * Retrieves an iterator of @element's pads. The iterator should
1174 * be freed after usage. Also more specialized iterators exists such as
1175 * gst_element_iterate_src_pads() or gst_element_iterate_sink_pads().
1177 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1183 gst_element_iterate_pads (GstElement * element)
1185 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1187 return gst_element_iterate_pad_list (element, &element->pads);
1191 * gst_element_iterate_src_pads:
1192 * @element: a #GstElement.
1194 * Retrieves an iterator of @element's source pads.
1196 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1202 gst_element_iterate_src_pads (GstElement * element)
1204 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1206 return gst_element_iterate_pad_list (element, &element->srcpads);
1210 * gst_element_iterate_sink_pads:
1211 * @element: a #GstElement.
1213 * Retrieves an iterator of @element's sink pads.
1215 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1221 gst_element_iterate_sink_pads (GstElement * element)
1223 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1225 return gst_element_iterate_pad_list (element, &element->sinkpads);
1229 * gst_element_class_add_pad_template:
1230 * @klass: the #GstElementClass to add the pad template to.
1231 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1233 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1234 * functions of classes. If a pad template with the same name as an already
1235 * existing one is added the old one is replaced by the new one.
1239 gst_element_class_add_pad_template (GstElementClass * klass,
1240 GstPadTemplate * templ)
1242 GList *template_list = klass->padtemplates;
1244 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1245 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1247 /* If we already have a pad template with the same name replace the
1249 while (template_list) {
1250 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1252 /* Found pad with the same name, replace and return */
1253 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1254 gst_object_unref (padtempl);
1255 template_list->data = templ;
1258 template_list = g_list_next (template_list);
1261 /* Take ownership of the floating ref */
1262 g_object_ref_sink (templ);
1264 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1265 klass->numpadtemplates++;
1269 * gst_element_class_add_metadata:
1270 * @klass: class to set metadata for
1271 * @key: the key to set
1272 * @value: the value to set
1274 * Set @key with @value as metadata in @klass.
1277 gst_element_class_add_metadata (GstElementClass * klass,
1278 const gchar * key, const gchar * value)
1280 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1281 g_return_if_fail (key != NULL);
1282 g_return_if_fail (value != NULL);
1284 gst_structure_set ((GstStructure *) klass->metadata,
1285 key, G_TYPE_STRING, value, NULL);
1289 * gst_element_class_set_metadata:
1290 * @klass: class to set metadata for
1291 * @longname: The long English name of the element. E.g. "File Sink"
1292 * @classification: String describing the type of element, as an unordered list
1293 * separated with slashes ('/'). See draft-klass.txt of the design docs
1294 * for more details and common types. E.g: "Sink/File"
1295 * @description: Sentence describing the purpose of the element.
1296 * E.g: "Write stream to a file"
1297 * @author: Name and contact details of the author(s). Use \n to separate
1298 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1300 * Sets the detailed information for a #GstElementClass.
1301 * <note>This function is for use in _class_init functions only.</note>
1304 gst_element_class_set_metadata (GstElementClass * klass,
1305 const gchar * longname, const gchar * classification,
1306 const gchar * description, const gchar * author)
1308 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1310 gst_structure_set ((GstStructure *) klass->metadata,
1311 GST_ELEMENT_METADATA_LONGNAME, G_TYPE_STRING, longname,
1312 GST_ELEMENT_METADATA_KLASS, G_TYPE_STRING, classification,
1313 GST_ELEMENT_METADATA_DESCRIPTION, G_TYPE_STRING, description,
1314 GST_ELEMENT_METADATA_AUTHOR, G_TYPE_STRING, author, NULL);
1318 * gst_element_class_get_metadata:
1319 * @klass: class to get metadata for
1320 * @key: the key to get
1322 * Get metadata with @key in @klass.
1324 * Returns: the metadata for @key.
1327 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1329 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1330 g_return_val_if_fail (key != NULL, NULL);
1332 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1336 * gst_element_class_get_pad_template_list:
1337 * @element_class: a #GstElementClass to get pad templates of.
1339 * Retrieves a list of the pad templates associated with @element_class. The
1340 * list must not be modified by the calling code.
1341 * <note>If you use this function in the #GInstanceInitFunc of an object class
1342 * that has subclasses, make sure to pass the g_class parameter of the
1343 * #GInstanceInitFunc here.</note>
1345 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1349 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1351 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1353 return element_class->padtemplates;
1357 * gst_element_class_get_pad_template:
1358 * @element_class: a #GstElementClass to get the pad template of.
1359 * @name: the name of the #GstPadTemplate to get.
1361 * Retrieves a padtemplate from @element_class with the given name.
1362 * <note>If you use this function in the #GInstanceInitFunc of an object class
1363 * that has subclasses, make sure to pass the g_class parameter of the
1364 * #GInstanceInitFunc here.</note>
1366 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1367 * if none was found. No unreferencing is necessary.
1370 gst_element_class_get_pad_template (GstElementClass *
1371 element_class, const gchar * name)
1375 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1376 g_return_val_if_fail (name != NULL, NULL);
1378 padlist = element_class->padtemplates;
1381 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1383 if (strcmp (padtempl->name_template, name) == 0)
1386 padlist = g_list_next (padlist);
1392 static GstPadTemplate *
1393 gst_element_class_get_request_pad_template (GstElementClass *
1394 element_class, const gchar * name)
1396 GstPadTemplate *tmpl;
1398 tmpl = gst_element_class_get_pad_template (element_class, name);
1399 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1405 /* get a random pad on element of the given direction.
1406 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1409 gst_element_get_random_pad (GstElement * element,
1410 gboolean need_linked, GstPadDirection dir)
1412 GstPad *result = NULL;
1415 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1419 GST_OBJECT_LOCK (element);
1420 pads = element->srcpads;
1423 GST_OBJECT_LOCK (element);
1424 pads = element->sinkpads;
1427 goto wrong_direction;
1429 for (; pads; pads = g_list_next (pads)) {
1430 GstPad *pad = GST_PAD_CAST (pads->data);
1432 GST_OBJECT_LOCK (pad);
1433 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1434 GST_DEBUG_PAD_NAME (pad));
1436 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1437 /* if we require a linked pad, and it is not linked, continue the
1439 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1440 GST_DEBUG_PAD_NAME (pad));
1441 GST_OBJECT_UNLOCK (pad);
1444 /* found a pad, stop search */
1445 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1446 GST_DEBUG_PAD_NAME (pad));
1447 GST_OBJECT_UNLOCK (pad);
1453 gst_object_ref (result);
1455 GST_OBJECT_UNLOCK (element);
1459 /* ERROR handling */
1462 g_warning ("unknown pad direction %d", dir);
1468 gst_element_default_send_event (GstElement * element, GstEvent * event)
1470 gboolean result = FALSE;
1473 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1474 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1475 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1478 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1479 "pushing %s event to random %s pad %s:%s",
1480 GST_EVENT_TYPE_NAME (event),
1481 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1482 GST_DEBUG_PAD_NAME (pad));
1484 result = gst_pad_push_event (pad, event);
1485 gst_object_unref (pad);
1487 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1488 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1489 gst_event_unref (event);
1495 * gst_element_send_event:
1496 * @element: a #GstElement to send the event to.
1497 * @event: (transfer full): the #GstEvent to send to the element.
1499 * Sends an event to an element. If the element doesn't implement an
1500 * event handler, the event will be pushed on a random linked sink pad for
1501 * upstream events or a random linked source pad for downstream events.
1503 * This function takes owership of the provided event so you should
1504 * gst_event_ref() it if you want to reuse the event after this call.
1506 * Returns: %TRUE if the event was handled.
1511 gst_element_send_event (GstElement * element, GstEvent * event)
1513 GstElementClass *oclass;
1514 gboolean result = FALSE;
1516 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1517 g_return_val_if_fail (event != NULL, FALSE);
1519 oclass = GST_ELEMENT_GET_CLASS (element);
1521 GST_STATE_LOCK (element);
1522 if (oclass->send_event) {
1523 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1524 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1525 result = oclass->send_event (element, event);
1527 GST_STATE_UNLOCK (element);
1534 * @element: a #GstElement to send the event to.
1535 * @rate: The new playback rate
1536 * @format: The format of the seek values
1537 * @flags: The optional seek flags.
1538 * @cur_type: The type and flags for the new current position
1539 * @cur: The value of the new current position
1540 * @stop_type: The type and flags for the new stop position
1541 * @stop: The value of the new stop position
1543 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1544 * the parameters. The seek event is sent to the element using
1545 * gst_element_send_event().
1547 * Returns: %TRUE if the event was handled.
1552 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1553 GstSeekFlags flags, GstSeekType cur_type, gint64 cur,
1554 GstSeekType stop_type, gint64 stop)
1559 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1562 gst_event_new_seek (rate, format, flags, cur_type, cur, stop_type, stop);
1563 result = gst_element_send_event (element, event);
1569 gst_element_default_query (GstElement * element, GstQuery * query)
1571 gboolean result = FALSE;
1574 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1576 result = gst_pad_query (pad, query);
1578 gst_object_unref (pad);
1580 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1582 GstPad *peer = gst_pad_get_peer (pad);
1585 result = gst_pad_query (peer, query);
1587 gst_object_unref (peer);
1589 gst_object_unref (pad);
1596 * gst_element_query:
1597 * @element: a #GstElement to perform the query on.
1598 * @query: (transfer none): the #GstQuery.
1600 * Performs a query on the given element.
1602 * For elements that don't implement a query handler, this function
1603 * forwards the query to a random srcpad or to the peer of a
1604 * random linked sinkpad of this element.
1606 * Please note that some queries might need a running pipeline to work.
1608 * Returns: TRUE if the query could be performed.
1613 gst_element_query (GstElement * element, GstQuery * query)
1615 GstElementClass *oclass;
1616 gboolean result = FALSE;
1618 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1619 g_return_val_if_fail (query != NULL, FALSE);
1621 oclass = GST_ELEMENT_GET_CLASS (element);
1623 if (oclass->query) {
1624 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1625 GST_ELEMENT_NAME (element));
1626 result = oclass->query (element, query);
1632 * gst_element_post_message:
1633 * @element: a #GstElement posting the message
1634 * @message: (transfer full): a #GstMessage to post
1636 * Post a message on the element's #GstBus. This function takes ownership of the
1637 * message; if you want to access the message after this call, you should add an
1638 * additional reference before calling.
1640 * Returns: %TRUE if the message was successfully posted. The function returns
1641 * %FALSE if the element did not have a bus.
1646 gst_element_post_message (GstElement * element, GstMessage * message)
1649 gboolean result = FALSE;
1651 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1652 g_return_val_if_fail (message != NULL, FALSE);
1654 GST_OBJECT_LOCK (element);
1657 if (G_UNLIKELY (bus == NULL))
1660 gst_object_ref (bus);
1661 GST_OBJECT_UNLOCK (element);
1663 /* we release the element lock when posting the message so that any
1664 * (synchronous) message handlers can operate on the element */
1665 result = gst_bus_post (bus, message);
1666 gst_object_unref (bus);
1673 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1674 "not posting message %p: no bus", message);
1675 GST_OBJECT_UNLOCK (element);
1676 gst_message_unref (message);
1682 * _gst_element_error_printf:
1683 * @format: the printf-like format to use, or %NULL
1685 * This function is only used internally by the gst_element_error() macro.
1687 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1693 _gst_element_error_printf (const gchar * format, ...)
1703 va_start (args, format);
1704 buffer = g_strdup_vprintf (format, args);
1710 * gst_element_message_full:
1711 * @element: a #GstElement to send message from
1712 * @type: the #GstMessageType
1713 * @domain: the GStreamer GError domain this message belongs to
1714 * @code: the GError code belonging to the domain
1715 * @text: (allow-none) (transfer full): an allocated text string to be used
1716 * as a replacement for the default message connected to code,
1718 * @debug: (allow-none) (transfer full): an allocated debug message to be
1719 * used as a replacement for the default debugging information,
1721 * @file: the source code file where the error was generated
1722 * @function: the source code function where the error was generated
1723 * @line: the source code line where the error was generated
1725 * Post an error, warning or info message on the bus from inside an element.
1727 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1728 * #GST_MESSAGE_INFO.
1732 void gst_element_message_full
1733 (GstElement * element, GstMessageType type,
1734 GQuark domain, gint code, gchar * text,
1735 gchar * debug, const gchar * file, const gchar * function, gint line)
1737 GError *gerror = NULL;
1741 gboolean has_debug = TRUE;
1742 GstMessage *message = NULL;
1745 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1746 g_return_if_fail (GST_IS_ELEMENT (element));
1747 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1748 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1750 /* check if we send the given text or the default error text */
1751 if ((text == NULL) || (text[0] == 0)) {
1752 /* text could have come from g_strdup_printf (""); */
1754 sent_text = gst_error_get_message (domain, code);
1758 /* construct a sent_debug with extra information from source */
1759 if ((debug == NULL) || (debug[0] == 0)) {
1760 /* debug could have come from g_strdup_printf (""); */
1764 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1766 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1767 file, line, function, name, debug);
1769 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1770 file, line, function, name);
1774 /* create gerror and post message */
1775 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1777 gerror = g_error_new_literal (domain, code, sent_text);
1780 case GST_MESSAGE_ERROR:
1782 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1784 case GST_MESSAGE_WARNING:
1785 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1788 case GST_MESSAGE_INFO:
1789 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1793 g_assert_not_reached ();
1796 gst_element_post_message (element, message);
1798 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1799 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1802 g_error_free (gerror);
1803 g_free (sent_debug);
1808 * gst_element_is_locked_state:
1809 * @element: a #GstElement.
1811 * Checks if the state of an element is locked.
1812 * If the state of an element is locked, state changes of the parent don't
1813 * affect the element.
1814 * This way you can leave currently unused elements inside bins. Just lock their
1815 * state before changing the state from #GST_STATE_NULL.
1819 * Returns: TRUE, if the element's state is locked.
1822 gst_element_is_locked_state (GstElement * element)
1826 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1828 GST_OBJECT_LOCK (element);
1829 result = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1830 GST_OBJECT_UNLOCK (element);
1836 * gst_element_set_locked_state:
1837 * @element: a #GstElement
1838 * @locked_state: TRUE to lock the element's state
1840 * Locks the state of an element, so state changes of the parent don't affect
1841 * this element anymore.
1845 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1846 * or the elements state-locking needed no change.
1849 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1853 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1855 GST_OBJECT_LOCK (element);
1856 old = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1858 if (G_UNLIKELY (old == locked_state))
1862 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1863 GST_ELEMENT_NAME (element));
1864 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_LOCKED_STATE);
1866 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1867 GST_ELEMENT_NAME (element));
1868 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_LOCKED_STATE);
1870 GST_OBJECT_UNLOCK (element);
1876 GST_CAT_DEBUG (GST_CAT_STATES,
1877 "elements %s was already in locked state %d",
1878 GST_ELEMENT_NAME (element), old);
1879 GST_OBJECT_UNLOCK (element);
1886 * gst_element_sync_state_with_parent:
1887 * @element: a #GstElement.
1889 * Tries to change the state of the element to the same as its parent.
1890 * If this function returns FALSE, the state of element is undefined.
1892 * Returns: TRUE, if the element's state could be synced to the parent's state.
1897 gst_element_sync_state_with_parent (GstElement * element)
1901 GstStateChangeReturn ret;
1903 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1905 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1906 GstState parent_current, parent_pending;
1908 GST_OBJECT_LOCK (parent);
1909 parent_current = GST_STATE (parent);
1910 parent_pending = GST_STATE_PENDING (parent);
1911 GST_OBJECT_UNLOCK (parent);
1913 /* set to pending if there is one, else we set it to the current state of
1915 if (parent_pending != GST_STATE_VOID_PENDING)
1916 target = parent_pending;
1918 target = parent_current;
1920 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1921 "syncing state (%s) to parent %s %s (%s, %s)",
1922 gst_element_state_get_name (GST_STATE (element)),
1923 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1924 gst_element_state_get_name (parent_current),
1925 gst_element_state_get_name (parent_pending));
1927 ret = gst_element_set_state (element, target);
1928 if (ret == GST_STATE_CHANGE_FAILURE)
1931 gst_object_unref (parent);
1935 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
1942 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1943 "syncing state failed (%s)",
1944 gst_element_state_change_return_get_name (ret));
1945 gst_object_unref (parent);
1951 static GstStateChangeReturn
1952 gst_element_get_state_func (GstElement * element,
1953 GstState * state, GstState * pending, GstClockTime timeout)
1955 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
1956 GstState old_pending;
1958 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
1959 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
1961 GST_OBJECT_LOCK (element);
1962 ret = GST_STATE_RETURN (element);
1963 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
1964 gst_element_state_change_return_get_name (ret));
1966 /* we got an error, report immediately */
1967 if (ret == GST_STATE_CHANGE_FAILURE)
1970 /* we got no_preroll, report immediately */
1971 if (ret == GST_STATE_CHANGE_NO_PREROLL)
1974 /* no need to wait async if we are not async */
1975 if (ret != GST_STATE_CHANGE_ASYNC)
1978 old_pending = GST_STATE_PENDING (element);
1979 if (old_pending != GST_STATE_VOID_PENDING) {
1980 GTimeVal *timeval, abstimeout;
1983 if (timeout != GST_CLOCK_TIME_NONE) {
1984 glong add = timeout / 1000;
1989 /* make timeout absolute */
1990 g_get_current_time (&abstimeout);
1991 g_time_val_add (&abstimeout, add);
1992 timeval = &abstimeout;
1996 /* get cookie to detect state changes during waiting */
1997 cookie = element->state_cookie;
1999 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2000 "waiting for element to commit state");
2002 /* we have a pending state change, wait for it to complete */
2003 if (!GST_STATE_TIMED_WAIT (element, timeval)) {
2004 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2005 /* timeout triggered */
2006 ret = GST_STATE_CHANGE_ASYNC;
2008 if (cookie != element->state_cookie)
2011 /* could be success or failure */
2012 if (old_pending == GST_STATE (element)) {
2013 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2014 ret = GST_STATE_CHANGE_SUCCESS;
2016 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2017 ret = GST_STATE_CHANGE_FAILURE;
2020 /* if nothing is pending anymore we can return SUCCESS */
2021 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2022 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2023 ret = GST_STATE_CHANGE_SUCCESS;
2029 *state = GST_STATE (element);
2031 *pending = GST_STATE_PENDING (element);
2033 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2034 "state current: %s, pending: %s, result: %s",
2035 gst_element_state_get_name (GST_STATE (element)),
2036 gst_element_state_get_name (GST_STATE_PENDING (element)),
2037 gst_element_state_change_return_get_name (ret));
2038 GST_OBJECT_UNLOCK (element);
2045 *state = GST_STATE_VOID_PENDING;
2047 *pending = GST_STATE_VOID_PENDING;
2049 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2051 GST_OBJECT_UNLOCK (element);
2053 return GST_STATE_CHANGE_FAILURE;
2058 * gst_element_get_state:
2059 * @element: a #GstElement to get the state of.
2060 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2062 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2063 * state. Can be %NULL.
2064 * @timeout: a #GstClockTime to specify the timeout for an async
2065 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2067 * Gets the state of the element.
2069 * For elements that performed an ASYNC state change, as reported by
2070 * gst_element_set_state(), this function will block up to the
2071 * specified timeout value for the state change to complete.
2072 * If the element completes the state change or goes into
2073 * an error, this function returns immediately with a return value of
2074 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2076 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2077 * returns the current and pending state immediately.
2079 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2080 * successfully changed its state but is not able to provide data yet.
2081 * This mostly happens for live sources that only produce data in
2082 * %GST_STATE_PLAYING. While the state change return is equivalent to
2083 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2084 * some sink elements might not be able to complete their state change because
2085 * an element is not producing data to complete the preroll. When setting the
2086 * element to playing, the preroll will complete and playback will start.
2088 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2089 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2090 * element is still performing a state change or
2091 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2095 GstStateChangeReturn
2096 gst_element_get_state (GstElement * element,
2097 GstState * state, GstState * pending, GstClockTime timeout)
2099 GstElementClass *oclass;
2100 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2102 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2104 oclass = GST_ELEMENT_GET_CLASS (element);
2106 if (oclass->get_state)
2107 result = (oclass->get_state) (element, state, pending, timeout);
2113 * gst_element_abort_state:
2114 * @element: a #GstElement to abort the state of.
2116 * Abort the state change of the element. This function is used
2117 * by elements that do asynchronous state changes and find out
2118 * something is wrong.
2120 * This function should be called with the STATE_LOCK held.
2125 gst_element_abort_state (GstElement * element)
2129 #ifndef GST_DISABLE_GST_DEBUG
2133 g_return_if_fail (GST_IS_ELEMENT (element));
2135 GST_OBJECT_LOCK (element);
2136 pending = GST_STATE_PENDING (element);
2138 if (pending == GST_STATE_VOID_PENDING ||
2139 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2140 goto nothing_aborted;
2142 #ifndef GST_DISABLE_GST_DEBUG
2143 old_state = GST_STATE (element);
2145 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2146 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2147 gst_element_state_get_name (pending));
2151 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2153 GST_STATE_BROADCAST (element);
2154 GST_OBJECT_UNLOCK (element);
2160 GST_OBJECT_UNLOCK (element);
2165 /* Not static because GstBin has manual state handling too */
2167 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2168 GstState newstate, GstState pending)
2170 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2171 GstMessage *message;
2173 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2174 "notifying about state-changed %s to %s (%s pending)",
2175 gst_element_state_get_name (oldstate),
2176 gst_element_state_get_name (newstate),
2177 gst_element_state_get_name (pending));
2179 if (klass->state_changed)
2180 klass->state_changed (element, oldstate, newstate, pending);
2182 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2183 oldstate, newstate, pending);
2184 gst_element_post_message (element, message);
2188 * gst_element_continue_state:
2189 * @element: a #GstElement to continue the state change of.
2190 * @ret: The previous state return value
2192 * Commit the state change of the element and proceed to the next
2193 * pending state if any. This function is used
2194 * by elements that do asynchronous state changes.
2195 * The core will normally call this method automatically when an
2196 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2198 * If after calling this method the element still has not reached
2199 * the pending state, the next state change is performed.
2201 * This method is used internally and should normally not be called by plugins
2204 * Returns: The result of the commit state change.
2208 GstStateChangeReturn
2209 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2211 GstStateChangeReturn old_ret;
2212 GstState old_state, old_next;
2213 GstState current, next, pending;
2214 GstStateChange transition;
2216 GST_OBJECT_LOCK (element);
2217 old_ret = GST_STATE_RETURN (element);
2218 GST_STATE_RETURN (element) = ret;
2219 pending = GST_STATE_PENDING (element);
2221 /* check if there is something to commit */
2222 if (pending == GST_STATE_VOID_PENDING)
2223 goto nothing_pending;
2225 old_state = GST_STATE (element);
2226 /* this is the state we should go to next */
2227 old_next = GST_STATE_NEXT (element);
2228 /* update current state */
2229 current = GST_STATE (element) = old_next;
2231 /* see if we reached the final state */
2232 if (pending == current)
2235 next = GST_STATE_GET_NEXT (current, pending);
2236 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2238 GST_STATE_NEXT (element) = next;
2240 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2241 GST_OBJECT_UNLOCK (element);
2243 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2244 "committing state from %s to %s, pending %s, next %s",
2245 gst_element_state_get_name (old_state),
2246 gst_element_state_get_name (old_next),
2247 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2249 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2251 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2252 "continue state change %s to %s, final %s",
2253 gst_element_state_get_name (current),
2254 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2256 ret = gst_element_change_state (element, transition);
2262 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2263 GST_OBJECT_UNLOCK (element);
2268 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2269 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2271 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2272 "completed state change to %s", gst_element_state_get_name (pending));
2273 GST_OBJECT_UNLOCK (element);
2275 /* don't post silly messages with the same state. This can happen
2276 * when an element state is changed to what it already was. For bins
2277 * this can be the result of a lost state, which we check with the
2278 * previous return value.
2279 * We do signal the cond though as a _get_state() might be blocking
2281 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2282 _priv_gst_element_state_changed (element, old_state, old_next,
2283 GST_STATE_VOID_PENDING);
2285 GST_STATE_BROADCAST (element);
2292 * gst_element_lost_state:
2293 * @element: a #GstElement the state is lost of
2295 * Brings the element to the lost state. The current state of the
2296 * element is copied to the pending state so that any call to
2297 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2299 * An ASYNC_START message is posted. If the element was PLAYING, it will
2300 * go to PAUSED. The element will be restored to its PLAYING state by
2301 * the parent pipeline when it prerolls again.
2303 * This is mostly used for elements that lost their preroll buffer
2304 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2305 * they will go to their pending state again when a new preroll buffer is
2306 * queued. This function can only be called when the element is currently
2307 * not in error or an async state change.
2309 * This function is used internally and should normally not be called from
2310 * plugins or applications.
2313 gst_element_lost_state (GstElement * element)
2315 GstState old_state, new_state;
2316 GstMessage *message;
2318 g_return_if_fail (GST_IS_ELEMENT (element));
2320 GST_OBJECT_LOCK (element);
2321 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2324 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2325 goto only_async_start;
2327 old_state = GST_STATE (element);
2329 /* when we were PLAYING, the new state is PAUSED. We will also not
2330 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2331 * when we preroll. */
2332 if (old_state > GST_STATE_PAUSED)
2333 new_state = GST_STATE_PAUSED;
2335 new_state = old_state;
2337 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2338 "lost state of %s to %s", gst_element_state_get_name (old_state),
2339 gst_element_state_get_name (new_state));
2341 GST_STATE (element) = new_state;
2342 GST_STATE_NEXT (element) = new_state;
2343 GST_STATE_PENDING (element) = new_state;
2344 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2345 GST_OBJECT_UNLOCK (element);
2347 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2349 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2350 gst_element_post_message (element, message);
2356 GST_OBJECT_UNLOCK (element);
2361 GST_OBJECT_UNLOCK (element);
2363 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2364 gst_element_post_message (element, message);
2370 * gst_element_set_state:
2371 * @element: a #GstElement to change state of.
2372 * @state: the element's new #GstState.
2374 * Sets the state of the element. This function will try to set the
2375 * requested state by going through all the intermediary states and calling
2376 * the class's state change function for each.
2378 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2379 * element will perform the remainder of the state change asynchronously in
2381 * An application can use gst_element_get_state() to wait for the completion
2382 * of the state change or it can wait for a state change message on the bus.
2384 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2385 * #GST_STATE_CHANGE_ASYNC.
2387 * Returns: Result of the state change using #GstStateChangeReturn.
2391 GstStateChangeReturn
2392 gst_element_set_state (GstElement * element, GstState state)
2394 GstElementClass *oclass;
2395 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2397 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2399 oclass = GST_ELEMENT_GET_CLASS (element);
2401 if (oclass->set_state)
2402 result = (oclass->set_state) (element, state);
2408 * default set state function, calculates the next state based
2409 * on current state and calls the change_state function
2411 static GstStateChangeReturn
2412 gst_element_set_state_func (GstElement * element, GstState state)
2414 GstState current, next, old_pending;
2415 GstStateChangeReturn ret;
2416 GstStateChange transition;
2417 GstStateChangeReturn old_ret;
2419 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2421 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2422 gst_element_state_get_name (state));
2424 /* state lock is taken to protect the set_state() and get_state()
2425 * procedures, it does not lock any variables. */
2426 GST_STATE_LOCK (element);
2428 /* now calculate how to get to the new state */
2429 GST_OBJECT_LOCK (element);
2430 old_ret = GST_STATE_RETURN (element);
2431 /* previous state change returned an error, remove all pending
2432 * and next states */
2433 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2434 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2435 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2436 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2439 current = GST_STATE (element);
2440 next = GST_STATE_NEXT (element);
2441 old_pending = GST_STATE_PENDING (element);
2443 /* this is the (new) state we should go to. TARGET is the last state we set on
2445 if (state != GST_STATE_TARGET (element)) {
2446 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2447 "setting target state to %s", gst_element_state_get_name (state));
2448 GST_STATE_TARGET (element) = state;
2449 /* increment state cookie so that we can track each state change. We only do
2450 * this if this is actually a new state change. */
2451 element->state_cookie++;
2453 GST_STATE_PENDING (element) = state;
2455 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2456 "current %s, old_pending %s, next %s, old return %s",
2457 gst_element_state_get_name (current),
2458 gst_element_state_get_name (old_pending),
2459 gst_element_state_get_name (next),
2460 gst_element_state_change_return_get_name (old_ret));
2462 /* if the element was busy doing a state change, we just update the
2463 * target state, it'll get to it async then. */
2464 if (old_pending != GST_STATE_VOID_PENDING) {
2465 /* upwards state change will happen ASYNC */
2466 if (old_pending <= state)
2468 /* element is going to this state already */
2469 else if (next == state)
2471 /* element was performing an ASYNC upward state change and
2472 * we request to go downward again. Start from the next pending
2474 else if (next > state
2475 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2479 next = GST_STATE_GET_NEXT (current, state);
2480 /* now we store the next state */
2481 GST_STATE_NEXT (element) = next;
2482 /* mark busy, we need to check that there is actually a state change
2483 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2484 * the default element change_state function has no way to know what the
2485 * old value was... could consider this a FIXME...*/
2486 if (current != next)
2487 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2489 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2491 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2492 "%s: setting state from %s to %s",
2493 (next != state ? "intermediate" : "final"),
2494 gst_element_state_get_name (current), gst_element_state_get_name (next));
2496 /* now signal any waiters, they will error since the cookie was incremented */
2497 GST_STATE_BROADCAST (element);
2499 GST_OBJECT_UNLOCK (element);
2501 ret = gst_element_change_state (element, transition);
2503 GST_STATE_UNLOCK (element);
2505 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2506 gst_element_state_change_return_get_name (ret));
2512 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2513 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2514 "element was busy with async state change");
2515 GST_OBJECT_UNLOCK (element);
2517 GST_STATE_UNLOCK (element);
2519 return GST_STATE_CHANGE_ASYNC;
2524 * gst_element_change_state:
2525 * @element: a #GstElement
2526 * @transition: the requested transition
2528 * Perform @transition on @element.
2530 * This function must be called with STATE_LOCK held and is mainly used
2533 * Returns: the #GstStateChangeReturn of the state transition.
2535 GstStateChangeReturn
2536 gst_element_change_state (GstElement * element, GstStateChange transition)
2538 GstElementClass *oclass;
2539 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2541 oclass = GST_ELEMENT_GET_CLASS (element);
2543 /* call the state change function so it can set the state */
2544 if (oclass->change_state)
2545 ret = (oclass->change_state) (element, transition);
2547 ret = GST_STATE_CHANGE_FAILURE;
2550 case GST_STATE_CHANGE_FAILURE:
2551 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2552 "have FAILURE change_state return");
2553 /* state change failure */
2554 gst_element_abort_state (element);
2556 case GST_STATE_CHANGE_ASYNC:
2560 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2561 "element will change state ASYNC");
2563 target = GST_STATE_TARGET (element);
2565 if (target > GST_STATE_READY)
2568 /* else we just continue the state change downwards */
2569 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2570 "forcing commit state %s <= %s",
2571 gst_element_state_get_name (target),
2572 gst_element_state_get_name (GST_STATE_READY));
2574 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2577 case GST_STATE_CHANGE_SUCCESS:
2578 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2579 "element changed state SUCCESS");
2580 /* we can commit the state now which will proceeed to
2582 ret = gst_element_continue_state (element, ret);
2584 case GST_STATE_CHANGE_NO_PREROLL:
2585 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2586 "element changed state NO_PREROLL");
2587 /* we can commit the state now which will proceeed to
2589 ret = gst_element_continue_state (element, ret);
2592 goto invalid_return;
2595 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2600 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2608 GST_OBJECT_LOCK (element);
2609 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2610 g_critical ("%s: unknown return value %d from a state change function",
2611 GST_ELEMENT_NAME (element), ret);
2613 /* we are in error now */
2614 ret = GST_STATE_CHANGE_FAILURE;
2615 GST_STATE_RETURN (element) = ret;
2616 GST_OBJECT_UNLOCK (element);
2622 /* gst_iterator_fold functions for pads_activate
2623 * Stop the iterator if activating one pad failed. */
2625 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2627 GstPad *pad = g_value_get_object (vpad);
2628 gboolean cont = TRUE;
2630 if (!(cont = gst_pad_set_active (pad, *active)))
2631 g_value_set_boolean (ret, FALSE);
2636 /* returns false on error or early cutout of the fold, true if all
2637 * pads in @iter were (de)activated successfully. */
2639 iterator_activate_fold_with_resync (GstIterator * iter,
2640 GstIteratorFoldFunction func, gpointer user_data)
2642 GstIteratorResult ires;
2645 /* no need to unset this later, it's just a boolean */
2646 g_value_init (&ret, G_TYPE_BOOLEAN);
2647 g_value_set_boolean (&ret, TRUE);
2650 ires = gst_iterator_fold (iter, func, &ret, user_data);
2652 case GST_ITERATOR_RESYNC:
2653 /* need to reset the result again */
2654 g_value_set_boolean (&ret, TRUE);
2655 gst_iterator_resync (iter);
2657 case GST_ITERATOR_DONE:
2658 /* all pads iterated, return collected value */
2661 /* iterator returned _ERROR or premature end with _OK,
2662 * mark an error and exit */
2663 g_value_set_boolean (&ret, FALSE);
2668 /* return collected value */
2669 return g_value_get_boolean (&ret);
2672 /* is called with STATE_LOCK
2674 * Pads are activated from source pads to sinkpads.
2677 gst_element_pads_activate (GstElement * element, gboolean active)
2682 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2683 "pads_activate with active %d", active);
2685 iter = gst_element_iterate_src_pads (element);
2687 iterator_activate_fold_with_resync (iter,
2688 (GstIteratorFoldFunction) activate_pads, &active);
2689 gst_iterator_free (iter);
2690 if (G_UNLIKELY (!res))
2693 iter = gst_element_iterate_sink_pads (element);
2695 iterator_activate_fold_with_resync (iter,
2696 (GstIteratorFoldFunction) activate_pads, &active);
2697 gst_iterator_free (iter);
2698 if (G_UNLIKELY (!res))
2701 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2702 "pads_activate successful");
2709 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2710 "source pads_activate failed");
2715 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2716 "sink pads_activate failed");
2721 /* is called with STATE_LOCK */
2722 static GstStateChangeReturn
2723 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2725 GstState state, next;
2726 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2728 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2730 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2731 next = GST_STATE_TRANSITION_NEXT (transition);
2733 /* if the element already is in the given state, we just return success */
2734 if (next == GST_STATE_VOID_PENDING || state == next)
2737 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2738 "default handler tries setting state from %s to %s (%04x)",
2739 gst_element_state_get_name (state),
2740 gst_element_state_get_name (next), transition);
2742 switch (transition) {
2743 case GST_STATE_CHANGE_NULL_TO_READY:
2745 case GST_STATE_CHANGE_READY_TO_PAUSED:
2746 if (!gst_element_pads_activate (element, TRUE)) {
2747 result = GST_STATE_CHANGE_FAILURE;
2750 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2752 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2754 case GST_STATE_CHANGE_PAUSED_TO_READY:
2755 case GST_STATE_CHANGE_READY_TO_NULL:
2756 /* deactivate pads in both cases, since they are activated on
2757 ready->paused but the element might not have made it to paused */
2758 if (!gst_element_pads_activate (element, FALSE)) {
2759 result = GST_STATE_CHANGE_FAILURE;
2763 /* this will catch real but unhandled state changes;
2764 * can only be caused by:
2765 * - a new state was added
2766 * - somehow the element was asked to jump across an intermediate state
2768 g_warning ("Unhandled state change from %s to %s",
2769 gst_element_state_get_name (state),
2770 gst_element_state_get_name (next));
2777 GST_OBJECT_LOCK (element);
2778 result = GST_STATE_RETURN (element);
2779 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2780 "element is already in the %s state",
2781 gst_element_state_get_name (state));
2782 GST_OBJECT_UNLOCK (element);
2789 * gst_element_get_factory:
2790 * @element: a #GstElement to request the element factory of.
2792 * Retrieves the factory that was used to create this element.
2794 * Returns: (transfer none): the #GstElementFactory used for creating this
2795 * element. no refcounting is needed.
2798 gst_element_get_factory (GstElement * element)
2800 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2802 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2806 gst_element_dispose (GObject * object)
2808 GstElement *element = GST_ELEMENT_CAST (object);
2812 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2814 if (GST_STATE (element) != GST_STATE_NULL)
2817 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2818 "removing %d pads", g_list_length (element->pads));
2819 /* first we break all our links with the outside */
2820 while (element->pads && element->pads->data) {
2821 /* don't call _remove_pad with NULL */
2822 gst_element_remove_pad (element, GST_PAD_CAST (element->pads->data));
2824 if (G_UNLIKELY (element->pads != NULL)) {
2825 g_critical ("could not remove pads from element %s",
2826 GST_STR_NULL (GST_OBJECT_NAME (object)));
2829 GST_OBJECT_LOCK (element);
2830 clock_p = &element->clock;
2831 bus_p = &element->bus;
2832 gst_object_replace ((GstObject **) clock_p, NULL);
2833 gst_object_replace ((GstObject **) bus_p, NULL);
2834 GST_OBJECT_UNLOCK (element);
2836 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2838 G_OBJECT_CLASS (parent_class)->dispose (object);
2847 is_locked = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
2849 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2851 "You need to explicitly set elements to the NULL state before\n"
2852 "dropping the final reference, to allow them to clean up.\n"
2853 "This problem may also be caused by a refcounting bug in the\n"
2854 "application or some element.\n",
2855 GST_OBJECT_NAME (element),
2856 gst_element_state_get_name (GST_STATE (element)),
2857 is_locked ? " (locked)" : "");
2863 gst_element_finalize (GObject * object)
2865 GstElement *element = GST_ELEMENT_CAST (object);
2867 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2869 g_cond_free (element->state_cond);
2870 g_static_rec_mutex_free (&element->state_lock);
2872 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2874 G_OBJECT_CLASS (parent_class)->finalize (object);
2878 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2882 g_return_if_fail (GST_IS_ELEMENT (element));
2884 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2886 GST_OBJECT_LOCK (element);
2887 bus_p = &GST_ELEMENT_BUS (element);
2888 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
2889 GST_OBJECT_UNLOCK (element);
2893 * gst_element_set_bus:
2894 * @element: a #GstElement to set the bus of.
2895 * @bus: (transfer none): the #GstBus to set.
2897 * Sets the bus of the element. Increases the refcount on the bus.
2898 * For internal use only, unless you're testing elements.
2903 gst_element_set_bus (GstElement * element, GstBus * bus)
2905 GstElementClass *oclass;
2907 g_return_if_fail (GST_IS_ELEMENT (element));
2909 oclass = GST_ELEMENT_GET_CLASS (element);
2911 if (oclass->set_bus)
2912 oclass->set_bus (element, bus);
2916 * gst_element_get_bus:
2917 * @element: a #GstElement to get the bus of.
2919 * Returns the bus of the element. Note that only a #GstPipeline will provide a
2920 * bus for the application.
2922 * Returns: (transfer full): the element's #GstBus. unref after usage.
2927 gst_element_get_bus (GstElement * element)
2929 GstBus *result = NULL;
2931 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
2933 GST_OBJECT_LOCK (element);
2934 if ((result = GST_ELEMENT_BUS (element)))
2935 gst_object_ref (result);
2936 GST_OBJECT_UNLOCK (element);
2938 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,