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 "gstelementdetails.h"
86 #include "gstenumtypes.h"
88 #include "gstmarshal.h"
94 #include "gst-i18n-lib.h"
96 /* Element signals and args */
112 #ifdef GST_DISABLE_DEPRECATED
113 #if !defined(GST_DISABLE_LOADSAVE) && !defined(GST_REMOVE_DEPRECATED)
114 #include <libxml/parser.h>
115 xmlNodePtr gst_object_save_thyself (const GstObject * object,
117 GstObject *gst_object_load_thyself (xmlNodePtr parent);
118 void gst_pad_load_and_link (xmlNodePtr self, GstObject * parent);
122 static void gst_element_class_init (GstElementClass * klass);
123 static void gst_element_init (GstElement * element);
124 static void gst_element_base_class_init (gpointer g_class);
125 static void gst_element_base_class_finalize (gpointer g_class);
127 static void gst_element_dispose (GObject * object);
128 static void gst_element_finalize (GObject * object);
130 static GstStateChangeReturn gst_element_change_state_func (GstElement * element,
131 GstStateChange transition);
132 static GstStateChangeReturn gst_element_get_state_func (GstElement * element,
133 GstState * state, GstState * pending, GstClockTime timeout);
134 static GstStateChangeReturn gst_element_set_state_func (GstElement * element,
136 static void gst_element_set_bus_func (GstElement * element, GstBus * bus);
138 static gboolean gst_element_default_send_event (GstElement * element,
140 static gboolean gst_element_default_query (GstElement * element,
143 static GstPadTemplate
144 * gst_element_class_get_request_pad_template (GstElementClass *
145 element_class, const gchar * name);
147 #if !defined(GST_DISABLE_LOADSAVE) && !defined(GST_REMOVE_DEPRECATED)
148 static xmlNodePtr gst_element_save_thyself (GstObject * object,
150 static void gst_element_restore_thyself (GstObject * parent, xmlNodePtr self);
153 static GstObjectClass *parent_class = NULL;
154 static guint gst_element_signals[LAST_SIGNAL] = { 0 };
156 /* this is used in gstelementfactory.c:gst_element_register() */
157 GQuark _gst_elementclass_factory = 0;
160 gst_element_get_type (void)
162 static volatile gsize gst_element_type = 0;
164 if (g_once_init_enter (&gst_element_type)) {
166 static const GTypeInfo element_info = {
167 sizeof (GstElementClass),
168 gst_element_base_class_init,
169 gst_element_base_class_finalize,
170 (GClassInitFunc) gst_element_class_init,
175 (GInstanceInitFunc) gst_element_init,
179 _type = g_type_register_static (GST_TYPE_OBJECT, "GstElement",
180 &element_info, G_TYPE_FLAG_ABSTRACT);
182 _gst_elementclass_factory =
183 g_quark_from_static_string ("GST_ELEMENTCLASS_FACTORY");
184 g_once_init_leave (&gst_element_type, _type);
186 return gst_element_type;
190 gst_element_class_init (GstElementClass * klass)
192 GObjectClass *gobject_class;
193 GstObjectClass *gstobject_class;
195 gobject_class = (GObjectClass *) klass;
196 gstobject_class = (GstObjectClass *) klass;
198 parent_class = g_type_class_peek_parent (klass);
201 * GstElement::pad-added:
202 * @gstelement: the object which received the signal
203 * @new_pad: the pad that has been added
205 * a new #GstPad has been added to the element. Note that this signal will
206 * usually be emitted from the context of the streaming thread. Also keep in
207 * mind that if you add new elements to the pipeline in the signal handler
208 * you will need to set them to the desired target state with
209 * gst_element_set() or gst_element_sync_state_with_parent().
211 gst_element_signals[PAD_ADDED] =
212 g_signal_new ("pad-added", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
213 G_STRUCT_OFFSET (GstElementClass, pad_added), NULL, NULL,
214 gst_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GST_TYPE_PAD);
216 * GstElement::pad-removed:
217 * @gstelement: the object which received the signal
218 * @old_pad: the pad that has been removed
220 * a #GstPad has been removed from the element
222 gst_element_signals[PAD_REMOVED] =
223 g_signal_new ("pad-removed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
224 G_STRUCT_OFFSET (GstElementClass, pad_removed), NULL, NULL,
225 gst_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GST_TYPE_PAD);
227 * GstElement::no-more-pads:
228 * @gstelement: the object which received the signal
230 * This signals that the element will not generate more dynamic pads.
231 * Note that this signal will usually be emitted from the context of
232 * the streaming thread.
234 gst_element_signals[NO_MORE_PADS] =
235 g_signal_new ("no-more-pads", G_TYPE_FROM_CLASS (klass),
236 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstElementClass, no_more_pads), NULL,
237 NULL, gst_marshal_VOID__VOID, G_TYPE_NONE, 0);
239 gobject_class->dispose = gst_element_dispose;
240 gobject_class->finalize = gst_element_finalize;
242 #if !defined(GST_DISABLE_LOADSAVE) && !defined(GST_REMOVE_DEPRECATED)
243 gstobject_class->save_thyself =
244 ((gpointer (*)(GstObject * object,
245 gpointer self)) * GST_DEBUG_FUNCPTR (gst_element_save_thyself));
246 gstobject_class->restore_thyself =
247 ((void (*)(GstObject * object,
248 gpointer self)) *GST_DEBUG_FUNCPTR (gst_element_restore_thyself));
251 klass->change_state = GST_DEBUG_FUNCPTR (gst_element_change_state_func);
252 klass->set_state = GST_DEBUG_FUNCPTR (gst_element_set_state_func);
253 klass->get_state = GST_DEBUG_FUNCPTR (gst_element_get_state_func);
254 klass->set_bus = GST_DEBUG_FUNCPTR (gst_element_set_bus_func);
255 klass->query = GST_DEBUG_FUNCPTR (gst_element_default_query);
256 klass->send_event = GST_DEBUG_FUNCPTR (gst_element_default_send_event);
257 klass->numpadtemplates = 0;
259 klass->elementfactory = NULL;
263 gst_element_base_class_init (gpointer g_class)
265 GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
267 /* FIXME 0.11: Copy the element details and instead of clearing the
268 * pad template list copy the list and increase the refcount of
269 * the pad templates by one.
271 * This will make it possible to add pad templates and set element
272 * details in the class_init functions and is the real GObject way
274 * See http://bugzilla.gnome.org/show_bug.cgi?id=491501
276 memset (&element_class->details, 0, sizeof (GstElementDetails));
277 element_class->meta_data = NULL;
278 element_class->padtemplates = NULL;
280 /* set the factory, see gst_element_register() */
281 element_class->elementfactory =
282 g_type_get_qdata (G_TYPE_FROM_CLASS (element_class),
283 _gst_elementclass_factory);
284 GST_DEBUG ("type %s : factory %p", G_OBJECT_CLASS_NAME (element_class),
285 element_class->elementfactory);
289 gst_element_base_class_finalize (gpointer g_class)
291 GstElementClass *klass = GST_ELEMENT_CLASS (g_class);
293 g_list_foreach (klass->padtemplates, (GFunc) gst_object_unref, NULL);
294 g_list_free (klass->padtemplates);
295 __gst_element_details_clear (&klass->details);
296 if (klass->meta_data) {
297 gst_structure_free (klass->meta_data);
298 klass->meta_data = NULL;
303 gst_element_init (GstElement * element)
305 GST_STATE (element) = GST_STATE_NULL;
306 GST_STATE_TARGET (element) = GST_STATE_NULL;
307 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
308 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
309 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
311 /* FIXME 0.11: Store this directly in the instance struct */
312 element->state_lock = g_slice_new (GStaticRecMutex);
313 g_static_rec_mutex_init (element->state_lock);
314 element->state_cond = g_cond_new ();
318 * gst_element_release_request_pad:
319 * @element: a #GstElement to release the request pad of.
320 * @pad: the #GstPad to release.
322 * Makes the element free the previously requested pad as obtained
323 * with gst_element_get_request_pad().
325 * This does not unref the pad. If the pad was created by using
326 * gst_element_get_request_pad(), gst_element_release_request_pad() needs to be
327 * followed by gst_object_unref() to free the @pad.
332 gst_element_release_request_pad (GstElement * element, GstPad * pad)
334 GstElementClass *oclass;
336 g_return_if_fail (GST_IS_ELEMENT (element));
337 g_return_if_fail (GST_IS_PAD (pad));
338 g_return_if_fail (GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
341 oclass = GST_ELEMENT_GET_CLASS (element);
343 /* if the element implements a custom release function we call that, else we
344 * simply remove the pad from the element */
345 if (oclass->release_pad)
346 (oclass->release_pad) (element, pad);
348 gst_element_remove_pad (element, pad);
352 * gst_element_requires_clock:
353 * @element: a #GstElement to query
355 * Query if the element requires a clock.
357 * Returns: %TRUE if the element requires a clock
362 gst_element_requires_clock (GstElement * element)
366 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
368 result = (GST_ELEMENT_GET_CLASS (element)->set_clock != NULL);
374 * gst_element_provides_clock:
375 * @element: a #GstElement to query
377 * Query if the element provides a clock. A #GstClock provided by an
378 * element can be used as the global #GstClock for the pipeline.
379 * An element that can provide a clock is only required to do so in the PAUSED
380 * state, this means when it is fully negotiated and has allocated the resources
381 * to operate the clock.
383 * Returns: %TRUE if the element provides a clock
388 gst_element_provides_clock (GstElement * element)
392 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
394 result = (GST_ELEMENT_GET_CLASS (element)->provide_clock != NULL);
400 * gst_element_provide_clock:
401 * @element: a #GstElement to query
403 * Get the clock provided by the given element.
404 * <note>An element is only required to provide a clock in the PAUSED
405 * state. Some elements can provide a clock in other states.</note>
407 * Returns: (transfer full): the GstClock provided by the element or %NULL
408 * if no clock could be provided. Unref after usage.
413 gst_element_provide_clock (GstElement * element)
415 GstClock *result = NULL;
416 GstElementClass *oclass;
418 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
420 oclass = GST_ELEMENT_GET_CLASS (element);
422 if (oclass->provide_clock)
423 result = oclass->provide_clock (element);
429 * gst_element_set_clock:
430 * @element: a #GstElement to set the clock for.
431 * @clock: the #GstClock to set for the element.
433 * Sets the clock for the element. This function increases the
434 * refcount on the clock. Any previously set clock on the object
437 * Returns: %TRUE if the element accepted the clock. An element can refuse a
438 * clock when it, for example, is not able to slave its internal clock to the
439 * @clock or when it requires a specific clock to operate.
444 gst_element_set_clock (GstElement * element, GstClock * clock)
446 GstElementClass *oclass;
450 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
451 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
453 oclass = GST_ELEMENT_GET_CLASS (element);
455 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
457 if (oclass->set_clock)
458 res = oclass->set_clock (element, clock);
461 /* only update the clock pointer if the element accepted the clock */
462 GST_OBJECT_LOCK (element);
463 clock_p = &element->clock;
464 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
465 GST_OBJECT_UNLOCK (element);
471 * gst_element_get_clock:
472 * @element: a #GstElement to get the clock of.
474 * Gets the currently configured clock of the element. This is the clock as was
475 * last set with gst_element_set_clock().
477 * Returns: (transfer full): the #GstClock of the element. unref after usage.
482 gst_element_get_clock (GstElement * element)
486 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
488 GST_OBJECT_LOCK (element);
489 if ((result = element->clock))
490 gst_object_ref (result);
491 GST_OBJECT_UNLOCK (element);
497 * gst_element_set_base_time:
498 * @element: a #GstElement.
499 * @time: the base time to set.
501 * Set the base time of an element. See gst_element_get_base_time().
506 gst_element_set_base_time (GstElement * element, GstClockTime time)
510 g_return_if_fail (GST_IS_ELEMENT (element));
512 GST_OBJECT_LOCK (element);
513 old = element->base_time;
514 element->base_time = time;
515 GST_OBJECT_UNLOCK (element);
517 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
518 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
519 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
523 * gst_element_get_base_time:
524 * @element: a #GstElement.
526 * Returns the base time of the element. The base time is the
527 * absolute time of the clock when this element was last put to
528 * PLAYING. Subtracting the base time from the clock time gives
529 * the running time of the element.
531 * Returns: the base time of the element.
536 gst_element_get_base_time (GstElement * element)
540 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
542 GST_OBJECT_LOCK (element);
543 result = element->base_time;
544 GST_OBJECT_UNLOCK (element);
550 * gst_element_set_start_time:
551 * @element: a #GstElement.
552 * @time: the base time to set.
554 * Set the start time of an element. The start time of the element is the
555 * running time of the element when it last went to the PAUSED state. In READY
556 * or after a flushing seek, it is set to 0.
558 * Toplevel elements like #GstPipeline will manage the start_time and
559 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
560 * on such a toplevel element will disable the distribution of the base_time to
561 * the children and can be useful if the application manages the base_time
562 * itself, for example if you want to synchronize capture from multiple
563 * pipelines, and you can also ensure that the pipelines have the same clock.
570 gst_element_set_start_time (GstElement * element, GstClockTime time)
574 g_return_if_fail (GST_IS_ELEMENT (element));
576 GST_OBJECT_LOCK (element);
577 old = GST_ELEMENT_START_TIME (element);
578 GST_ELEMENT_START_TIME (element) = time;
579 GST_OBJECT_UNLOCK (element);
581 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
582 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
583 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
587 * gst_element_get_start_time:
588 * @element: a #GstElement.
590 * Returns the start time of the element. The start time is the
591 * running time of the clock when this element was last put to PAUSED.
593 * Usually the start_time is managed by a toplevel element such as
598 * Returns: the start time of the element.
603 gst_element_get_start_time (GstElement * element)
607 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
609 GST_OBJECT_LOCK (element);
610 result = GST_ELEMENT_START_TIME (element);
611 GST_OBJECT_UNLOCK (element);
617 * gst_element_is_indexable:
618 * @element: a #GstElement.
620 * Queries if the element can be indexed.
622 * Returns: TRUE if the element can be indexed.
627 gst_element_is_indexable (GstElement * element)
631 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
633 result = (GST_ELEMENT_GET_CLASS (element)->set_index != NULL);
639 * gst_element_set_index:
640 * @element: a #GstElement.
641 * @index: (transfer none): a #GstIndex.
643 * Set @index on the element. The refcount of the index
644 * will be increased, any previously set index is unreffed.
649 gst_element_set_index (GstElement * element, GstIndex * index)
651 GstElementClass *oclass;
653 g_return_if_fail (GST_IS_ELEMENT (element));
654 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
656 oclass = GST_ELEMENT_GET_CLASS (element);
658 if (oclass->set_index)
659 oclass->set_index (element, index);
663 * gst_element_get_index:
664 * @element: a #GstElement.
666 * Gets the index from the element.
668 * Returns: (transfer full): a #GstIndex or %NULL when no index was set on the
669 * element. unref after usage.
674 gst_element_get_index (GstElement * element)
676 GstElementClass *oclass;
677 GstIndex *result = NULL;
679 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
681 oclass = GST_ELEMENT_GET_CLASS (element);
683 if (oclass->get_index)
684 result = oclass->get_index (element);
690 * gst_element_add_pad:
691 * @element: a #GstElement to add the pad to.
692 * @pad: (transfer full): the #GstPad to add to the element.
694 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
695 * see gst_object_set_parent() for refcounting information.
697 * Pads are not automatically activated so elements should perform the needed
698 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
699 * state. See gst_pad_set_active() for more information about activating pads.
701 * The pad and the element should be unlocked when calling this function.
703 * This function will emit the #GstElement::pad-added signal on the element.
705 * Returns: %TRUE if the pad could be added. This function can fail when
706 * a pad with the same name already existed or the pad already had another
712 gst_element_add_pad (GstElement * element, GstPad * pad)
717 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
718 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
720 /* locking pad to look at the name */
721 GST_OBJECT_LOCK (pad);
722 pad_name = g_strdup (GST_PAD_NAME (pad));
723 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
724 GST_STR_NULL (pad_name));
725 flushing = GST_PAD_IS_FLUSHING (pad);
726 GST_OBJECT_UNLOCK (pad);
728 /* then check to see if there's already a pad by that name here */
729 GST_OBJECT_LOCK (element);
730 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
733 /* try to set the pad's parent */
734 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
735 GST_OBJECT_CAST (element))))
738 /* check for flushing pads */
739 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
740 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
741 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
742 "use gst_pad_set_active(pad,TRUE) before adding it.",
743 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
745 GST_OBJECT_LOCK (pad);
746 GST_PAD_UNSET_FLUSHING (pad);
747 GST_OBJECT_UNLOCK (pad);
752 /* add it to the list */
753 switch (gst_pad_get_direction (pad)) {
755 element->srcpads = g_list_prepend (element->srcpads, pad);
756 element->numsrcpads++;
759 element->sinkpads = g_list_prepend (element->sinkpads, pad);
760 element->numsinkpads++;
765 element->pads = g_list_prepend (element->pads, pad);
767 element->pads_cookie++;
768 GST_OBJECT_UNLOCK (element);
770 /* emit the PAD_ADDED signal */
771 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
778 g_critical ("Padname %s is not unique in element %s, not adding",
779 pad_name, GST_ELEMENT_NAME (element));
780 GST_OBJECT_UNLOCK (element);
787 ("Pad %s already has parent when trying to add to element %s",
788 pad_name, GST_ELEMENT_NAME (element));
789 GST_OBJECT_UNLOCK (element);
795 GST_OBJECT_LOCK (pad);
797 ("Trying to add pad %s to element %s, but it has no direction",
798 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
799 GST_OBJECT_UNLOCK (pad);
800 GST_OBJECT_UNLOCK (element);
806 * gst_element_remove_pad:
807 * @element: a #GstElement to remove pad from.
808 * @pad: (transfer none): the #GstPad to remove from the element.
810 * Removes @pad from @element. @pad will be destroyed if it has not been
811 * referenced elsewhere using gst_object_unparent().
813 * This function is used by plugin developers and should not be used
814 * by applications. Pads that were dynamically requested from elements
815 * with gst_element_get_request_pad() should be released with the
816 * gst_element_release_request_pad() function instead.
818 * Pads are not automatically deactivated so elements should perform the needed
819 * steps to deactivate the pad in case this pad is removed in the PAUSED or
820 * PLAYING state. See gst_pad_set_active() for more information about
823 * The pad and the element should be unlocked when calling this function.
825 * This function will emit the #GstElement::pad-removed signal on the element.
827 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
828 * pad does not belong to the provided element.
833 gst_element_remove_pad (GstElement * element, GstPad * pad)
837 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
838 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
840 /* locking pad to look at the name and parent */
841 GST_OBJECT_LOCK (pad);
842 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
843 GST_STR_NULL (GST_PAD_NAME (pad)));
845 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
847 GST_OBJECT_UNLOCK (pad);
850 if ((peer = gst_pad_get_peer (pad))) {
851 /* window for MT unsafeness, someone else could unlink here
852 * and then we call unlink with wrong pads. The unlink
853 * function would catch this and safely return failed. */
854 if (GST_PAD_IS_SRC (pad))
855 gst_pad_unlink (pad, peer);
857 gst_pad_unlink (peer, pad);
859 gst_object_unref (peer);
862 GST_OBJECT_LOCK (element);
863 /* remove it from the list */
864 switch (gst_pad_get_direction (pad)) {
866 element->srcpads = g_list_remove (element->srcpads, pad);
867 element->numsrcpads--;
870 element->sinkpads = g_list_remove (element->sinkpads, pad);
871 element->numsinkpads--;
874 g_critical ("Removing pad without direction???");
877 element->pads = g_list_remove (element->pads, pad);
879 element->pads_cookie++;
880 GST_OBJECT_UNLOCK (element);
882 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
883 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
885 gst_object_unparent (GST_OBJECT_CAST (pad));
892 /* FIXME, locking order? */
893 GST_OBJECT_LOCK (element);
894 g_critical ("Padname %s:%s does not belong to element %s when removing",
895 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
896 GST_OBJECT_UNLOCK (element);
897 GST_OBJECT_UNLOCK (pad);
903 * gst_element_no_more_pads:
904 * @element: a #GstElement
906 * Use this function to signal that the element does not expect any more pads
907 * to show up in the current pipeline. This function should be called whenever
908 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
909 * pad templates use this in combination with autopluggers to figure out that
910 * the element is done initializing its pads.
912 * This function emits the #GstElement::no-more-pads signal.
917 gst_element_no_more_pads (GstElement * element)
919 g_return_if_fail (GST_IS_ELEMENT (element));
921 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
925 pad_compare_name (GstPad * pad1, const gchar * name)
929 GST_OBJECT_LOCK (pad1);
930 result = strcmp (GST_PAD_NAME (pad1), name);
931 GST_OBJECT_UNLOCK (pad1);
937 * gst_element_get_static_pad:
938 * @element: a #GstElement to find a static pad of.
939 * @name: the name of the static #GstPad to retrieve.
941 * Retrieves a pad from @element by name. This version only retrieves
942 * already-existing (i.e. 'static') pads.
944 * Returns: (transfer full): the requested #GstPad if found, otherwise %NULL.
950 gst_element_get_static_pad (GstElement * element, const gchar * name)
953 GstPad *result = NULL;
955 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
956 g_return_val_if_fail (name != NULL, NULL);
958 GST_OBJECT_LOCK (element);
960 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
962 result = GST_PAD_CAST (find->data);
963 gst_object_ref (result);
966 if (result == NULL) {
967 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
968 name, GST_ELEMENT_NAME (element));
970 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
971 GST_ELEMENT_NAME (element), name);
973 GST_OBJECT_UNLOCK (element);
979 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
980 const gchar * name, const GstCaps * caps)
982 GstPad *newpad = NULL;
983 GstElementClass *oclass;
985 oclass = GST_ELEMENT_GET_CLASS (element);
987 if (oclass->request_new_pad_full)
988 newpad = (oclass->request_new_pad_full) (element, templ, name, caps);
989 else if (oclass->request_new_pad)
990 newpad = (oclass->request_new_pad) (element, templ, name);
993 gst_object_ref (newpad);
999 * gst_element_get_request_pad:
1000 * @element: a #GstElement to find a request pad of.
1001 * @name: the name of the request #GstPad to retrieve.
1003 * Retrieves a pad from the element by name. This version only retrieves
1004 * request pads. The pad should be released with
1005 * gst_element_release_request_pad().
1007 * This method is slow and will be deprecated in the future. New code should
1008 * use gst_element_request_pad() with the requested template.
1010 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1011 * Release after usage.
1014 gst_element_get_request_pad (GstElement * element, const gchar * name)
1016 GstPadTemplate *templ = NULL;
1018 const gchar *req_name = NULL;
1019 gboolean templ_found = FALSE;
1022 gchar *str, *endptr = NULL;
1023 GstElementClass *class;
1025 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1026 g_return_val_if_fail (name != NULL, NULL);
1028 class = GST_ELEMENT_GET_CLASS (element);
1030 /* if the name contains a %, we assume it's the complete template name. Get
1031 * the template and try to get a pad */
1032 if (strstr (name, "%")) {
1033 templ = gst_element_class_get_request_pad_template (class, name);
1038 /* there is no % in the name, try to find a matching template */
1039 list = class->padtemplates;
1040 while (!templ_found && list) {
1041 templ = (GstPadTemplate *) list->data;
1042 if (templ->presence == GST_PAD_REQUEST) {
1043 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1044 templ->name_template);
1045 /* see if we find an exact match */
1046 if (strcmp (name, templ->name_template) == 0) {
1051 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1052 and %d, occurring at the end of the name_template, are the only
1054 else if ((str = strchr (templ->name_template, '%'))
1055 && strncmp (templ->name_template, name,
1056 str - templ->name_template) == 0
1057 && strlen (name) > str - templ->name_template) {
1058 data = name + (str - templ->name_template);
1059 if (*(str + 1) == 'd') {
1063 tmp = strtol (data, &endptr, 10);
1064 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1085 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1091 * gst_element_request_pad:
1092 * @element: a #GstElement to find a request pad of.
1093 * @templ: a #GstPadTemplate of which we want a pad of.
1094 * @name: (transfer none) (allow-none): the name of the request #GstPad
1095 * to retrieve. Can be %NULL.
1096 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1097 * request. Can be %NULL.
1099 * Retrieves a request pad from the element according to the provided template.
1101 * If the @caps are specified and the element implements thew new
1102 * request_new_pad_full virtual method, the element will use them to select
1103 * which pad to create.
1105 * The pad should be released with gst_element_release_request_pad().
1107 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1108 * Release after usage.
1113 gst_element_request_pad (GstElement * element,
1114 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1116 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1117 g_return_val_if_fail (templ != NULL, NULL);
1119 return _gst_element_request_pad (element, templ, name, caps);
1123 * gst_element_get_pad:
1124 * @element: a #GstElement.
1125 * @name: the name of the pad to retrieve.
1127 * Retrieves a pad from @element by name. Tries gst_element_get_static_pad()
1128 * first, then gst_element_get_request_pad().
1130 * Deprecated: This function is deprecated as it's unclear if the reference
1131 * to the result pad should be released with gst_object_unref() in case of a static pad
1132 * or gst_element_release_request_pad() in case of a request pad.
1133 * Use gst_element_get_static_pad() or gst_element_get_request_pad() instead.
1135 * Returns: (transfer full): the #GstPad if found, otherwise %NULL. Unref or Release after usage,
1136 * depending on the type of the pad.
1138 #ifndef GST_REMOVE_DEPRECATED
1139 #ifdef GST_DISABLE_DEPRECATED
1140 GstPad *gst_element_get_pad (GstElement * element, const gchar * name);
1143 gst_element_get_pad (GstElement * element, const gchar * name)
1147 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1148 g_return_val_if_fail (name != NULL, NULL);
1150 pad = gst_element_get_static_pad (element, name);
1152 pad = gst_element_get_request_pad (element, name);
1156 #endif /* GST_REMOVE_DEPRECATED */
1158 static GstIteratorItem
1159 iterate_pad (GstIterator * it, GstPad * pad)
1161 gst_object_ref (pad);
1162 return GST_ITERATOR_ITEM_PASS;
1165 static GstIterator *
1166 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1168 GstIterator *result;
1170 GST_OBJECT_LOCK (element);
1171 gst_object_ref (element);
1172 result = gst_iterator_new_list (GST_TYPE_PAD,
1173 GST_OBJECT_GET_LOCK (element),
1174 &element->pads_cookie,
1177 (GstIteratorItemFunction) iterate_pad,
1178 (GstIteratorDisposeFunction) gst_object_unref);
1179 GST_OBJECT_UNLOCK (element);
1185 * gst_element_iterate_pads:
1186 * @element: a #GstElement to iterate pads of.
1188 * Retrieves an iterattor of @element's pads. The iterator should
1189 * be freed after usage.
1191 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1197 gst_element_iterate_pads (GstElement * element)
1199 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1201 return gst_element_iterate_pad_list (element, &element->pads);
1205 * gst_element_iterate_src_pads:
1206 * @element: a #GstElement.
1208 * Retrieves an iterator of @element's source pads.
1210 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1216 gst_element_iterate_src_pads (GstElement * element)
1218 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1220 return gst_element_iterate_pad_list (element, &element->srcpads);
1224 * gst_element_iterate_sink_pads:
1225 * @element: a #GstElement.
1227 * Retrieves an iterator of @element's sink pads.
1229 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1235 gst_element_iterate_sink_pads (GstElement * element)
1237 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1239 return gst_element_iterate_pad_list (element, &element->sinkpads);
1243 * gst_element_class_add_pad_template:
1244 * @klass: the #GstElementClass to add the pad template to.
1245 * @templ: (transfer none): a #GstPadTemplate to add to the element class.
1247 * Adds a padtemplate to an element class. This is mainly used in the _base_init
1248 * functions of classes.
1251 gst_element_class_add_pad_template (GstElementClass * klass,
1252 GstPadTemplate * templ)
1254 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1255 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1257 /* FIXME 0.11: allow replacing the pad templates by
1258 * calling this with the same name as an already existing pad
1259 * template. For this we _must_ _not_ ref the added pad template
1260 * a second time and _must_ document that this function takes
1261 * ownership of the pad template. Otherwise we will leak pad templates
1262 * or the caller unref's the pad template and it disappears */
1263 /* avoid registering pad templates with the same name */
1264 g_return_if_fail (gst_element_class_get_pad_template (klass,
1265 templ->name_template) == NULL);
1267 klass->padtemplates = g_list_append (klass->padtemplates,
1268 gst_object_ref (templ));
1269 klass->numpadtemplates++;
1273 gst_element_class_add_meta_data (GstElementClass * klass,
1274 const gchar * key, const gchar * value)
1276 if (!klass->meta_data) {
1277 /* FIXME: use a quark for "metadata" */
1278 klass->meta_data = gst_structure_empty_new ("metadata");
1281 gst_structure_set ((GstStructure *) klass->meta_data,
1282 key, G_TYPE_STRING, value, NULL);
1286 * gst_element_class_set_documentation_uri:
1287 * @klass: class to set details for
1288 * @uri: uri of element documentation
1290 * Set uri pointing to user documentation. Applications can use this to show
1291 * help for e.g. effects to users.
1296 gst_element_class_set_documentation_uri (GstElementClass * klass,
1299 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1301 gst_element_class_add_meta_data (klass, "doc-uri", uri);
1305 * gst_element_class_set_icon_name:
1306 * @klass: class to set details for
1307 * @name: name of an icon
1309 * Elements that bridge to certain other products can include an icon of that
1310 * used product. Application can show the icon in menus/selectors to help
1311 * identifying specific elements.
1316 gst_element_class_set_icon_name (GstElementClass * klass, const gchar * name)
1318 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1320 gst_element_class_add_meta_data (klass, "icon-name", name);
1323 /* FIXME-0.11: deprecate and remove gst_element_class_set_details*() */
1325 * gst_element_class_set_details:
1326 * @klass: class to set details for
1327 * @details: details to set
1329 * Sets the detailed information for a #GstElementClass.
1330 * <note>This function is for use in _base_init functions only.</note>
1332 * The @details are copied.
1334 * Deprecated: Use gst_element_class_set_details_simple() instead.
1336 #ifndef GST_REMOVE_DEPRECATED
1337 #ifdef GST_DISABLE_DEPRECATED
1339 gst_element_class_set_details (GstElementClass * klass,
1340 const GstElementDetails * details);
1343 gst_element_class_set_details (GstElementClass * klass,
1344 const GstElementDetails * details)
1346 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1347 g_return_if_fail (GST_IS_ELEMENT_DETAILS (details));
1349 __gst_element_details_copy (&klass->details, details);
1354 * gst_element_class_set_details_simple:
1355 * @klass: class to set details for
1356 * @longname: The long English name of the element. E.g. "File Sink"
1357 * @classification: String describing the type of element, as an unordered list
1358 * separated with slashes ('/'). See draft-klass.txt of the design docs
1359 * for more details and common types. E.g: "Sink/File"
1360 * @description: Sentence describing the purpose of the element.
1361 * E.g: "Write stream to a file"
1362 * @author: Name and contact details of the author(s). Use \n to separate
1363 * multiple author details. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1365 * Sets the detailed information for a #GstElementClass. Simpler version of
1366 * gst_element_class_set_details() that generates less linker overhead.
1367 * <note>This function is for use in _base_init functions only.</note>
1369 * The detail parameter strings are copied into the #GstElementDetails for
1370 * the element class.
1375 gst_element_class_set_details_simple (GstElementClass * klass,
1376 const gchar * longname, const gchar * classification,
1377 const gchar * description, const gchar * author)
1379 const GstElementDetails details =
1380 GST_ELEMENT_DETAILS ((gchar *) longname, (gchar *) classification,
1381 (gchar *) description, (gchar *) author);
1383 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1385 __gst_element_details_copy (&klass->details, &details);
1389 * gst_element_class_get_pad_template_list:
1390 * @element_class: a #GstElementClass to get pad templates of.
1392 * Retrieves a list of the pad templates associated with @element_class. The
1393 * list must not be modified by the calling code.
1394 * <note>If you use this function in the #GInstanceInitFunc of an object class
1395 * that has subclasses, make sure to pass the g_class parameter of the
1396 * #GInstanceInitFunc here.</note>
1398 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1402 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1404 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1406 return element_class->padtemplates;
1410 * gst_element_class_get_pad_template:
1411 * @element_class: a #GstElementClass to get the pad template of.
1412 * @name: the name of the #GstPadTemplate to get.
1414 * Retrieves a padtemplate from @element_class with the given name.
1415 * <note>If you use this function in the #GInstanceInitFunc of an object class
1416 * that has subclasses, make sure to pass the g_class parameter of the
1417 * #GInstanceInitFunc here.</note>
1419 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1420 * if none was found. No unreferencing is necessary.
1423 gst_element_class_get_pad_template (GstElementClass * element_class,
1428 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1429 g_return_val_if_fail (name != NULL, NULL);
1431 padlist = element_class->padtemplates;
1434 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1436 if (strcmp (padtempl->name_template, name) == 0)
1439 padlist = g_list_next (padlist);
1445 static GstPadTemplate *
1446 gst_element_class_get_request_pad_template (GstElementClass * element_class,
1449 GstPadTemplate *tmpl;
1451 tmpl = gst_element_class_get_pad_template (element_class, name);
1452 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1458 /* get a random pad on element of the given direction.
1459 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1462 gst_element_get_random_pad (GstElement * element, gboolean need_linked,
1463 GstPadDirection dir)
1465 GstPad *result = NULL;
1468 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1472 GST_OBJECT_LOCK (element);
1473 pads = element->srcpads;
1476 GST_OBJECT_LOCK (element);
1477 pads = element->sinkpads;
1480 goto wrong_direction;
1482 for (; pads; pads = g_list_next (pads)) {
1483 GstPad *pad = GST_PAD_CAST (pads->data);
1485 GST_OBJECT_LOCK (pad);
1486 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1487 GST_DEBUG_PAD_NAME (pad));
1489 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1490 /* if we require a linked pad, and it is not linked, continue the
1492 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1493 GST_DEBUG_PAD_NAME (pad));
1494 GST_OBJECT_UNLOCK (pad);
1497 /* found a pad, stop search */
1498 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1499 GST_DEBUG_PAD_NAME (pad));
1500 GST_OBJECT_UNLOCK (pad);
1506 gst_object_ref (result);
1508 GST_OBJECT_UNLOCK (element);
1512 /* ERROR handling */
1515 g_warning ("unknown pad direction %d", dir);
1521 gst_element_default_send_event (GstElement * element, GstEvent * event)
1523 gboolean result = FALSE;
1526 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1527 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1528 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1531 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1532 "pushing %s event to random %s pad %s:%s",
1533 GST_EVENT_TYPE_NAME (event),
1534 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1535 GST_DEBUG_PAD_NAME (pad));
1537 result = gst_pad_push_event (pad, event);
1538 gst_object_unref (pad);
1540 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1541 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1547 * gst_element_send_event:
1548 * @element: a #GstElement to send the event to.
1549 * @event: (transfer full): the #GstEvent to send to the element.
1551 * Sends an event to an element. If the element doesn't implement an
1552 * event handler, the event will be pushed on a random linked sink pad for
1553 * upstream events or a random linked source pad for downstream events.
1555 * This function takes owership of the provided event so you should
1556 * gst_event_ref() it if you want to reuse the event after this call.
1558 * Returns: %TRUE if the event was handled.
1563 gst_element_send_event (GstElement * element, GstEvent * event)
1565 GstElementClass *oclass;
1566 gboolean result = FALSE;
1568 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1569 g_return_val_if_fail (event != NULL, FALSE);
1571 oclass = GST_ELEMENT_GET_CLASS (element);
1573 GST_STATE_LOCK (element);
1574 if (oclass->send_event) {
1575 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1576 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1577 result = oclass->send_event (element, event);
1579 result = gst_element_default_send_event (element, event);
1581 GST_STATE_UNLOCK (element);
1588 * @element: a #GstElement to send the event to.
1589 * @rate: The new playback rate
1590 * @format: The format of the seek values
1591 * @flags: The optional seek flags.
1592 * @cur_type: The type and flags for the new current position
1593 * @cur: The value of the new current position
1594 * @stop_type: The type and flags for the new stop position
1595 * @stop: The value of the new stop position
1597 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1598 * the parameters. The seek event is sent to the element using
1599 * gst_element_send_event().
1601 * Returns: %TRUE if the event was handled.
1606 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1607 GstSeekFlags flags, GstSeekType cur_type, gint64 cur,
1608 GstSeekType stop_type, gint64 stop)
1613 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1616 gst_event_new_seek (rate, format, flags, cur_type, cur, stop_type, stop);
1617 result = gst_element_send_event (element, event);
1623 * gst_element_get_query_types:
1624 * @element: a #GstElement to query
1626 * Get an array of query types from the element.
1627 * If the element doesn't implement a query types function,
1628 * the query will be forwarded to the peer of a random linked sink pad.
1630 * Returns: An array of #GstQueryType elements that should not
1631 * be freed or modified.
1635 const GstQueryType *
1636 gst_element_get_query_types (GstElement * element)
1638 GstElementClass *oclass;
1639 const GstQueryType *result = NULL;
1641 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1643 oclass = GST_ELEMENT_GET_CLASS (element);
1645 if (oclass->get_query_types) {
1646 result = oclass->get_query_types (element);
1648 GstPad *pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1651 GstPad *peer = gst_pad_get_peer (pad);
1654 result = gst_pad_get_query_types (peer);
1656 gst_object_unref (peer);
1658 gst_object_unref (pad);
1665 gst_element_default_query (GstElement * element, GstQuery * query)
1667 gboolean result = FALSE;
1670 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1672 result = gst_pad_query (pad, query);
1674 gst_object_unref (pad);
1676 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1678 GstPad *peer = gst_pad_get_peer (pad);
1681 result = gst_pad_query (peer, query);
1683 gst_object_unref (peer);
1685 gst_object_unref (pad);
1692 * gst_element_query:
1693 * @element: a #GstElement to perform the query on.
1694 * @query: (transfer none): the #GstQuery.
1696 * Performs a query on the given element.
1698 * For elements that don't implement a query handler, this function
1699 * forwards the query to a random srcpad or to the peer of a
1700 * random linked sinkpad of this element.
1702 * Please note that some queries might need a running pipeline to work.
1704 * Returns: TRUE if the query could be performed.
1709 gst_element_query (GstElement * element, GstQuery * query)
1711 GstElementClass *oclass;
1712 gboolean result = FALSE;
1714 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1715 g_return_val_if_fail (query != NULL, FALSE);
1717 oclass = GST_ELEMENT_GET_CLASS (element);
1719 if (oclass->query) {
1720 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1721 GST_ELEMENT_NAME (element));
1722 result = oclass->query (element, query);
1724 result = gst_element_default_query (element, query);
1730 * gst_element_post_message:
1731 * @element: a #GstElement posting the message
1732 * @message: (transfer full): a #GstMessage to post
1734 * Post a message on the element's #GstBus. This function takes ownership of the
1735 * message; if you want to access the message after this call, you should add an
1736 * additional reference before calling.
1738 * Returns: %TRUE if the message was successfully posted. The function returns
1739 * %FALSE if the element did not have a bus.
1744 gst_element_post_message (GstElement * element, GstMessage * message)
1747 gboolean result = FALSE;
1749 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1750 g_return_val_if_fail (message != NULL, FALSE);
1752 GST_OBJECT_LOCK (element);
1755 if (G_UNLIKELY (bus == NULL))
1758 gst_object_ref (bus);
1759 GST_OBJECT_UNLOCK (element);
1761 /* we release the element lock when posting the message so that any
1762 * (synchronous) message handlers can operate on the element */
1763 result = gst_bus_post (bus, message);
1764 gst_object_unref (bus);
1771 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1772 "not posting message %p: no bus", message);
1773 GST_OBJECT_UNLOCK (element);
1774 gst_message_unref (message);
1780 * _gst_element_error_printf:
1781 * @format: the printf-like format to use, or %NULL
1783 * This function is only used internally by the gst_element_error() macro.
1785 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1791 _gst_element_error_printf (const gchar * format, ...)
1801 va_start (args, format);
1802 buffer = g_strdup_vprintf (format, args);
1808 * gst_element_message_full:
1809 * @element: a #GstElement to send message from
1810 * @type: the #GstMessageType
1811 * @domain: the GStreamer GError domain this message belongs to
1812 * @code: the GError code belonging to the domain
1813 * @text: (allow-none) (transfer full): an allocated text string to be used
1814 * as a replacement for the default message connected to code,
1816 * @debug: (allow-none) (transfer full): an allocated debug message to be
1817 * used as a replacement for the default debugging information,
1819 * @file: the source code file where the error was generated
1820 * @function: the source code function where the error was generated
1821 * @line: the source code line where the error was generated
1823 * Post an error, warning or info message on the bus from inside an element.
1825 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1826 * #GST_MESSAGE_INFO.
1830 void gst_element_message_full
1831 (GstElement * element, GstMessageType type,
1832 GQuark domain, gint code, gchar * text,
1833 gchar * debug, const gchar * file, const gchar * function, gint line)
1835 GError *gerror = NULL;
1839 gboolean has_debug = TRUE;
1840 GstMessage *message = NULL;
1843 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1844 g_return_if_fail (GST_IS_ELEMENT (element));
1845 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1846 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1848 /* check if we send the given text or the default error text */
1849 if ((text == NULL) || (text[0] == 0)) {
1850 /* text could have come from g_strdup_printf (""); */
1852 sent_text = gst_error_get_message (domain, code);
1856 /* construct a sent_debug with extra information from source */
1857 if ((debug == NULL) || (debug[0] == 0)) {
1858 /* debug could have come from g_strdup_printf (""); */
1862 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1864 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1865 file, line, function, name, debug);
1867 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1868 file, line, function, name);
1872 /* create gerror and post message */
1873 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1875 gerror = g_error_new_literal (domain, code, sent_text);
1878 case GST_MESSAGE_ERROR:
1880 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1882 case GST_MESSAGE_WARNING:
1883 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1886 case GST_MESSAGE_INFO:
1887 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1891 g_assert_not_reached ();
1894 gst_element_post_message (element, message);
1896 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1897 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1900 g_error_free (gerror);
1901 g_free (sent_debug);
1906 * gst_element_is_locked_state:
1907 * @element: a #GstElement.
1909 * Checks if the state of an element is locked.
1910 * If the state of an element is locked, state changes of the parent don't
1911 * affect the element.
1912 * This way you can leave currently unused elements inside bins. Just lock their
1913 * state before changing the state from #GST_STATE_NULL.
1917 * Returns: TRUE, if the element's state is locked.
1920 gst_element_is_locked_state (GstElement * element)
1924 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1926 GST_OBJECT_LOCK (element);
1927 result = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1928 GST_OBJECT_UNLOCK (element);
1934 * gst_element_set_locked_state:
1935 * @element: a #GstElement
1936 * @locked_state: TRUE to lock the element's state
1938 * Locks the state of an element, so state changes of the parent don't affect
1939 * this element anymore.
1943 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1944 * or the elements state-locking needed no change.
1947 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1951 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1953 GST_OBJECT_LOCK (element);
1954 old = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1956 if (G_UNLIKELY (old == locked_state))
1960 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1961 GST_ELEMENT_NAME (element));
1962 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_LOCKED_STATE);
1964 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1965 GST_ELEMENT_NAME (element));
1966 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_LOCKED_STATE);
1968 GST_OBJECT_UNLOCK (element);
1974 GST_CAT_DEBUG (GST_CAT_STATES, "elements %s was already in locked state %d",
1975 GST_ELEMENT_NAME (element), old);
1976 GST_OBJECT_UNLOCK (element);
1983 * gst_element_sync_state_with_parent:
1984 * @element: a #GstElement.
1986 * Tries to change the state of the element to the same as its parent.
1987 * If this function returns FALSE, the state of element is undefined.
1989 * Returns: TRUE, if the element's state could be synced to the parent's state.
1994 gst_element_sync_state_with_parent (GstElement * element)
1998 GstStateChangeReturn ret;
2000 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
2002 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
2003 GstState parent_current, parent_pending;
2005 GST_OBJECT_LOCK (parent);
2006 parent_current = GST_STATE (parent);
2007 parent_pending = GST_STATE_PENDING (parent);
2008 GST_OBJECT_UNLOCK (parent);
2010 /* set to pending if there is one, else we set it to the current state of
2012 if (parent_pending != GST_STATE_VOID_PENDING)
2013 target = parent_pending;
2015 target = parent_current;
2017 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2018 "syncing state (%s) to parent %s %s (%s, %s)",
2019 gst_element_state_get_name (GST_STATE (element)),
2020 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
2021 gst_element_state_get_name (parent_current),
2022 gst_element_state_get_name (parent_pending));
2024 ret = gst_element_set_state (element, target);
2025 if (ret == GST_STATE_CHANGE_FAILURE)
2028 gst_object_unref (parent);
2032 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
2039 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2040 "syncing state failed (%s)",
2041 gst_element_state_change_return_get_name (ret));
2042 gst_object_unref (parent);
2048 static GstStateChangeReturn
2049 gst_element_get_state_func (GstElement * element,
2050 GstState * state, GstState * pending, GstClockTime timeout)
2052 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2053 GstState old_pending;
2055 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2056 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2058 GST_OBJECT_LOCK (element);
2059 ret = GST_STATE_RETURN (element);
2060 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2061 gst_element_state_change_return_get_name (ret));
2063 /* we got an error, report immediately */
2064 if (ret == GST_STATE_CHANGE_FAILURE)
2067 /* we got no_preroll, report immediatly */
2068 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2071 /* no need to wait async if we are not async */
2072 if (ret != GST_STATE_CHANGE_ASYNC)
2075 old_pending = GST_STATE_PENDING (element);
2076 if (old_pending != GST_STATE_VOID_PENDING) {
2077 GTimeVal *timeval, abstimeout;
2080 if (timeout != GST_CLOCK_TIME_NONE) {
2081 glong add = timeout / 1000;
2086 /* make timeout absolute */
2087 g_get_current_time (&abstimeout);
2088 g_time_val_add (&abstimeout, add);
2089 timeval = &abstimeout;
2093 /* get cookie to detect state changes during waiting */
2094 cookie = element->state_cookie;
2096 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2097 "waiting for element to commit state");
2099 /* we have a pending state change, wait for it to complete */
2100 if (!GST_STATE_TIMED_WAIT (element, timeval)) {
2101 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2102 /* timeout triggered */
2103 ret = GST_STATE_CHANGE_ASYNC;
2105 if (cookie != element->state_cookie)
2108 /* could be success or failure */
2109 if (old_pending == GST_STATE (element)) {
2110 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2111 ret = GST_STATE_CHANGE_SUCCESS;
2113 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2114 ret = GST_STATE_CHANGE_FAILURE;
2117 /* if nothing is pending anymore we can return SUCCESS */
2118 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2119 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2120 ret = GST_STATE_CHANGE_SUCCESS;
2126 *state = GST_STATE (element);
2128 *pending = GST_STATE_PENDING (element);
2130 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2131 "state current: %s, pending: %s, result: %s",
2132 gst_element_state_get_name (GST_STATE (element)),
2133 gst_element_state_get_name (GST_STATE_PENDING (element)),
2134 gst_element_state_change_return_get_name (ret));
2135 GST_OBJECT_UNLOCK (element);
2142 *state = GST_STATE_VOID_PENDING;
2144 *pending = GST_STATE_VOID_PENDING;
2146 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2148 GST_OBJECT_UNLOCK (element);
2150 return GST_STATE_CHANGE_FAILURE;
2155 * gst_element_get_state:
2156 * @element: a #GstElement to get the state of.
2157 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2159 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2160 * state. Can be %NULL.
2161 * @timeout: a #GstClockTime to specify the timeout for an async
2162 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2164 * Gets the state of the element.
2166 * For elements that performed an ASYNC state change, as reported by
2167 * gst_element_set_state(), this function will block up to the
2168 * specified timeout value for the state change to complete.
2169 * If the element completes the state change or goes into
2170 * an error, this function returns immediately with a return value of
2171 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2173 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2174 * returns the current and pending state immediately.
2176 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2177 * successfully changed its state but is not able to provide data yet.
2178 * This mostly happens for live sources that only produce data in
2179 * %GST_STATE_PLAYING. While the state change return is equivalent to
2180 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2181 * some sink elements might not be able to complete their state change because
2182 * an element is not producing data to complete the preroll. When setting the
2183 * element to playing, the preroll will complete and playback will start.
2185 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2186 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2187 * element is still performing a state change or
2188 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2192 GstStateChangeReturn
2193 gst_element_get_state (GstElement * element,
2194 GstState * state, GstState * pending, GstClockTime timeout)
2196 GstElementClass *oclass;
2197 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2199 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2201 oclass = GST_ELEMENT_GET_CLASS (element);
2203 if (oclass->get_state)
2204 result = (oclass->get_state) (element, state, pending, timeout);
2210 * gst_element_abort_state:
2211 * @element: a #GstElement to abort the state of.
2213 * Abort the state change of the element. This function is used
2214 * by elements that do asynchronous state changes and find out
2215 * something is wrong.
2217 * This function should be called with the STATE_LOCK held.
2222 gst_element_abort_state (GstElement * element)
2226 #ifndef GST_DISABLE_GST_DEBUG
2230 g_return_if_fail (GST_IS_ELEMENT (element));
2232 GST_OBJECT_LOCK (element);
2233 pending = GST_STATE_PENDING (element);
2235 if (pending == GST_STATE_VOID_PENDING ||
2236 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2237 goto nothing_aborted;
2239 #ifndef GST_DISABLE_GST_DEBUG
2240 old_state = GST_STATE (element);
2242 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2243 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2244 gst_element_state_get_name (pending));
2248 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2250 GST_STATE_BROADCAST (element);
2251 GST_OBJECT_UNLOCK (element);
2257 GST_OBJECT_UNLOCK (element);
2263 * gst_element_continue_state:
2264 * @element: a #GstElement to continue the state change of.
2265 * @ret: The previous state return value
2267 * Commit the state change of the element and proceed to the next
2268 * pending state if any. This function is used
2269 * by elements that do asynchronous state changes.
2270 * The core will normally call this method automatically when an
2271 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2273 * If after calling this method the element still has not reached
2274 * the pending state, the next state change is performed.
2276 * This method is used internally and should normally not be called by plugins
2279 * Returns: The result of the commit state change.
2283 GstStateChangeReturn
2284 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2286 GstStateChangeReturn old_ret;
2287 GstState old_state, old_next;
2288 GstState current, next, pending;
2289 GstMessage *message;
2290 GstStateChange transition;
2292 GST_OBJECT_LOCK (element);
2293 old_ret = GST_STATE_RETURN (element);
2294 GST_STATE_RETURN (element) = ret;
2295 pending = GST_STATE_PENDING (element);
2297 /* check if there is something to commit */
2298 if (pending == GST_STATE_VOID_PENDING)
2299 goto nothing_pending;
2301 old_state = GST_STATE (element);
2302 /* this is the state we should go to next */
2303 old_next = GST_STATE_NEXT (element);
2304 /* update current state */
2305 current = GST_STATE (element) = old_next;
2307 /* see if we reached the final state */
2308 if (pending == current)
2311 next = GST_STATE_GET_NEXT (current, pending);
2312 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2314 GST_STATE_NEXT (element) = next;
2316 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2317 GST_OBJECT_UNLOCK (element);
2319 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2320 "committing state from %s to %s, pending %s, next %s",
2321 gst_element_state_get_name (old_state),
2322 gst_element_state_get_name (old_next),
2323 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2325 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2326 old_state, old_next, pending);
2327 gst_element_post_message (element, message);
2329 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2330 "continue state change %s to %s, final %s",
2331 gst_element_state_get_name (current),
2332 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2334 ret = gst_element_change_state (element, transition);
2340 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2341 GST_OBJECT_UNLOCK (element);
2346 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2347 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2349 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2350 "completed state change to %s", gst_element_state_get_name (pending));
2351 GST_OBJECT_UNLOCK (element);
2353 /* don't post silly messages with the same state. This can happen
2354 * when an element state is changed to what it already was. For bins
2355 * this can be the result of a lost state, which we check with the
2356 * previous return value.
2357 * We do signal the cond though as a _get_state() might be blocking
2359 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC) {
2360 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2361 "posting state-changed %s to %s",
2362 gst_element_state_get_name (old_state),
2363 gst_element_state_get_name (old_next));
2365 gst_message_new_state_changed (GST_OBJECT_CAST (element), old_state,
2366 old_next, GST_STATE_VOID_PENDING);
2367 gst_element_post_message (element, message);
2370 GST_STATE_BROADCAST (element);
2377 * gst_element_lost_state_full:
2378 * @element: a #GstElement the state is lost of
2379 * @new_base_time: if a new base time should be distributed
2381 * Brings the element to the lost state. The current state of the
2382 * element is copied to the pending state so that any call to
2383 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2385 * An ASYNC_START message is posted with indication to distribute a new
2386 * base_time to the element when @new_base_time is %TRUE.
2387 * If the element was PLAYING, it will go to PAUSED. The element
2388 * will be restored to its PLAYING state by the parent pipeline when it
2391 * This is mostly used for elements that lost their preroll buffer
2392 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2393 * they will go to their pending state again when a new preroll buffer is
2394 * queued. This function can only be called when the element is currently
2395 * not in error or an async state change.
2397 * This function is used internally and should normally not be called from
2398 * plugins or applications.
2405 gst_element_lost_state_full (GstElement * element, gboolean new_base_time)
2407 GstState old_state, new_state;
2408 GstMessage *message;
2410 g_return_if_fail (GST_IS_ELEMENT (element));
2412 GST_OBJECT_LOCK (element);
2413 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2416 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2417 goto only_async_start;
2419 old_state = GST_STATE (element);
2421 /* when we were PLAYING, the new state is PAUSED. We will also not
2422 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2423 * when we preroll. */
2424 if (old_state > GST_STATE_PAUSED)
2425 new_state = GST_STATE_PAUSED;
2427 new_state = old_state;
2429 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2430 "lost state of %s to %s", gst_element_state_get_name (old_state),
2431 gst_element_state_get_name (new_state));
2433 GST_STATE (element) = new_state;
2434 GST_STATE_NEXT (element) = new_state;
2435 GST_STATE_PENDING (element) = new_state;
2436 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2438 GST_ELEMENT_START_TIME (element) = 0;
2439 GST_OBJECT_UNLOCK (element);
2441 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2442 new_state, new_state, new_state);
2443 gst_element_post_message (element, message);
2446 gst_message_new_async_start (GST_OBJECT_CAST (element), new_base_time);
2447 gst_element_post_message (element, message);
2453 GST_OBJECT_UNLOCK (element);
2458 GST_OBJECT_UNLOCK (element);
2460 message = gst_message_new_async_start (GST_OBJECT_CAST (element), TRUE);
2461 gst_element_post_message (element, message);
2467 * gst_element_lost_state:
2468 * @element: a #GstElement the state is lost of
2470 * Brings the element to the lost state. This function calls
2471 * gst_element_lost_state_full() with the new_base_time set to %TRUE.
2473 * This function is used internally and should normally not be called from
2474 * plugins or applications.
2479 gst_element_lost_state (GstElement * element)
2481 gst_element_lost_state_full (element, TRUE);
2485 * gst_element_set_state:
2486 * @element: a #GstElement to change state of.
2487 * @state: the element's new #GstState.
2489 * Sets the state of the element. This function will try to set the
2490 * requested state by going through all the intermediary states and calling
2491 * the class's state change function for each.
2493 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2494 * element will perform the remainder of the state change asynchronously in
2496 * An application can use gst_element_get_state() to wait for the completion
2497 * of the state change or it can wait for a state change message on the bus.
2499 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2500 * #GST_STATE_CHANGE_ASYNC.
2502 * Returns: Result of the state change using #GstStateChangeReturn.
2506 GstStateChangeReturn
2507 gst_element_set_state (GstElement * element, GstState state)
2509 GstElementClass *oclass;
2510 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2512 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2514 oclass = GST_ELEMENT_GET_CLASS (element);
2516 if (oclass->set_state)
2517 result = (oclass->set_state) (element, state);
2523 * default set state function, calculates the next state based
2524 * on current state and calls the change_state function
2526 static GstStateChangeReturn
2527 gst_element_set_state_func (GstElement * element, GstState state)
2529 GstState current, next, old_pending;
2530 GstStateChangeReturn ret;
2531 GstStateChange transition;
2532 GstStateChangeReturn old_ret;
2534 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2536 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2537 gst_element_state_get_name (state));
2539 /* state lock is taken to protect the set_state() and get_state()
2540 * procedures, it does not lock any variables. */
2541 GST_STATE_LOCK (element);
2543 /* now calculate how to get to the new state */
2544 GST_OBJECT_LOCK (element);
2545 old_ret = GST_STATE_RETURN (element);
2546 /* previous state change returned an error, remove all pending
2547 * and next states */
2548 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2549 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2550 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2551 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2554 current = GST_STATE (element);
2555 next = GST_STATE_NEXT (element);
2556 old_pending = GST_STATE_PENDING (element);
2558 /* this is the (new) state we should go to. TARGET is the last state we set on
2560 if (state != GST_STATE_TARGET (element)) {
2561 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2562 "setting target state to %s", gst_element_state_get_name (state));
2563 GST_STATE_TARGET (element) = state;
2564 /* increment state cookie so that we can track each state change. We only do
2565 * this if this is actually a new state change. */
2566 element->state_cookie++;
2568 GST_STATE_PENDING (element) = state;
2570 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2571 "current %s, old_pending %s, next %s, old return %s",
2572 gst_element_state_get_name (current),
2573 gst_element_state_get_name (old_pending),
2574 gst_element_state_get_name (next),
2575 gst_element_state_change_return_get_name (old_ret));
2577 /* if the element was busy doing a state change, we just update the
2578 * target state, it'll get to it async then. */
2579 if (old_pending != GST_STATE_VOID_PENDING) {
2580 /* upwards state change will happen ASYNC */
2581 if (old_pending <= state)
2583 /* element is going to this state already */
2584 else if (next == state)
2586 /* element was performing an ASYNC upward state change and
2587 * we request to go downward again. Start from the next pending
2589 else if (next > state
2590 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2594 next = GST_STATE_GET_NEXT (current, state);
2595 /* now we store the next state */
2596 GST_STATE_NEXT (element) = next;
2597 /* mark busy, we need to check that there is actually a state change
2598 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2599 * the default element change_state function has no way to know what the
2600 * old value was... could consider this a FIXME...*/
2601 if (current != next)
2602 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2604 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2606 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2607 "%s: setting state from %s to %s",
2608 (next != state ? "intermediate" : "final"),
2609 gst_element_state_get_name (current), gst_element_state_get_name (next));
2611 /* now signal any waiters, they will error since the cookie was incremented */
2612 GST_STATE_BROADCAST (element);
2614 GST_OBJECT_UNLOCK (element);
2616 ret = gst_element_change_state (element, transition);
2618 GST_STATE_UNLOCK (element);
2620 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2621 gst_element_state_change_return_get_name (ret));
2627 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2628 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2629 "element was busy with async state change");
2630 GST_OBJECT_UNLOCK (element);
2632 GST_STATE_UNLOCK (element);
2634 return GST_STATE_CHANGE_ASYNC;
2639 * gst_element_change_state:
2640 * @element: a #GstElement
2641 * @transition: the requested transition
2643 * Perform @transition on @element.
2645 * This function must be called with STATE_LOCK held and is mainly used
2648 * Returns: the #GstStateChangeReturn of the state transition.
2650 GstStateChangeReturn
2651 gst_element_change_state (GstElement * element, GstStateChange transition)
2653 GstElementClass *oclass;
2654 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2656 oclass = GST_ELEMENT_GET_CLASS (element);
2658 /* call the state change function so it can set the state */
2659 if (oclass->change_state)
2660 ret = (oclass->change_state) (element, transition);
2662 ret = GST_STATE_CHANGE_FAILURE;
2665 case GST_STATE_CHANGE_FAILURE:
2666 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2667 "have FAILURE change_state return");
2668 /* state change failure */
2669 gst_element_abort_state (element);
2671 case GST_STATE_CHANGE_ASYNC:
2675 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2676 "element will change state ASYNC");
2678 target = GST_STATE_TARGET (element);
2680 if (target > GST_STATE_READY)
2683 /* else we just continue the state change downwards */
2684 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2685 "forcing commit state %s <= %s",
2686 gst_element_state_get_name (target),
2687 gst_element_state_get_name (GST_STATE_READY));
2689 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2692 case GST_STATE_CHANGE_SUCCESS:
2693 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2694 "element changed state SUCCESS");
2695 /* we can commit the state now which will proceeed to
2697 ret = gst_element_continue_state (element, ret);
2699 case GST_STATE_CHANGE_NO_PREROLL:
2700 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2701 "element changed state NO_PREROLL");
2702 /* we can commit the state now which will proceeed to
2704 ret = gst_element_continue_state (element, ret);
2707 goto invalid_return;
2710 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2715 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2723 GST_OBJECT_LOCK (element);
2724 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2725 g_critical ("%s: unknown return value %d from a state change function",
2726 GST_ELEMENT_NAME (element), ret);
2728 /* we are in error now */
2729 ret = GST_STATE_CHANGE_FAILURE;
2730 GST_STATE_RETURN (element) = ret;
2731 GST_OBJECT_UNLOCK (element);
2737 /* gst_iterator_fold functions for pads_activate
2738 * Note how we don't stop the iterator when we fail an activation. This is
2739 * probably a FIXME since when one pad activation fails, we don't want to
2740 * continue our state change. */
2742 activate_pads (GstPad * pad, GValue * ret, gboolean * active)
2744 if (!gst_pad_set_active (pad, *active))
2745 g_value_set_boolean (ret, FALSE);
2747 /* unref the object that was reffed for us by _fold */
2748 gst_object_unref (pad);
2752 /* set the caps on the pad to NULL */
2754 clear_caps (GstPad * pad, GValue * ret, gboolean * active)
2756 gst_pad_set_caps (pad, NULL);
2757 gst_object_unref (pad);
2761 /* returns false on error or early cutout (will never happen because the fold
2762 * function always returns TRUE, see FIXME above) of the fold, true if all
2763 * pads in @iter were (de)activated successfully. */
2765 iterator_activate_fold_with_resync (GstIterator * iter,
2766 GstIteratorFoldFunction func, gpointer user_data)
2768 GstIteratorResult ires;
2771 /* no need to unset this later, it's just a boolean */
2772 g_value_init (&ret, G_TYPE_BOOLEAN);
2773 g_value_set_boolean (&ret, TRUE);
2776 ires = gst_iterator_fold (iter, func, &ret, user_data);
2778 case GST_ITERATOR_RESYNC:
2779 /* need to reset the result again */
2780 g_value_set_boolean (&ret, TRUE);
2781 gst_iterator_resync (iter);
2783 case GST_ITERATOR_DONE:
2784 /* all pads iterated, return collected value */
2787 /* iterator returned _ERROR or premature end with _OK,
2788 * mark an error and exit */
2789 g_value_set_boolean (&ret, FALSE);
2794 /* return collected value */
2795 return g_value_get_boolean (&ret);
2798 /* is called with STATE_LOCK
2800 * Pads are activated from source pads to sinkpads.
2803 gst_element_pads_activate (GstElement * element, gboolean active)
2808 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2809 "pads_activate with active %d", active);
2811 iter = gst_element_iterate_src_pads (element);
2813 iterator_activate_fold_with_resync (iter,
2814 (GstIteratorFoldFunction) activate_pads, &active);
2815 gst_iterator_free (iter);
2816 if (G_UNLIKELY (!res))
2819 iter = gst_element_iterate_sink_pads (element);
2821 iterator_activate_fold_with_resync (iter,
2822 (GstIteratorFoldFunction) activate_pads, &active);
2823 gst_iterator_free (iter);
2824 if (G_UNLIKELY (!res))
2828 /* clear the caps on all pads, this should never fail */
2829 iter = gst_element_iterate_pads (element);
2831 iterator_activate_fold_with_resync (iter,
2832 (GstIteratorFoldFunction) clear_caps, &active);
2833 gst_iterator_free (iter);
2834 if (G_UNLIKELY (!res))
2838 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2839 "pads_activate successful");
2846 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2847 "source pads_activate failed");
2852 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2853 "sink pads_activate failed");
2858 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2859 "failed to clear caps on pads");
2864 /* is called with STATE_LOCK */
2865 static GstStateChangeReturn
2866 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2868 GstState state, next;
2869 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2872 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2874 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2875 next = GST_STATE_TRANSITION_NEXT (transition);
2877 /* if the element already is in the given state, we just return success */
2878 if (next == GST_STATE_VOID_PENDING || state == next)
2881 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2882 "default handler tries setting state from %s to %s (%04x)",
2883 gst_element_state_get_name (state),
2884 gst_element_state_get_name (next), transition);
2886 switch (transition) {
2887 case GST_STATE_CHANGE_NULL_TO_READY:
2889 case GST_STATE_CHANGE_READY_TO_PAUSED:
2890 if (!gst_element_pads_activate (element, TRUE)) {
2891 result = GST_STATE_CHANGE_FAILURE;
2894 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2896 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2898 case GST_STATE_CHANGE_PAUSED_TO_READY:
2899 case GST_STATE_CHANGE_READY_TO_NULL:
2900 /* deactivate pads in both cases, since they are activated on
2901 ready->paused but the element might not have made it to paused */
2902 if (!gst_element_pads_activate (element, FALSE)) {
2903 result = GST_STATE_CHANGE_FAILURE;
2905 gst_element_set_base_time (element, 0);
2908 /* In null state release the reference to the clock */
2909 GST_OBJECT_LOCK (element);
2910 clock_p = &element->clock;
2911 gst_object_replace ((GstObject **) clock_p, NULL);
2912 GST_OBJECT_UNLOCK (element);
2915 /* this will catch real but unhandled state changes;
2916 * can only be caused by:
2917 * - a new state was added
2918 * - somehow the element was asked to jump across an intermediate state
2920 g_warning ("Unhandled state change from %s to %s",
2921 gst_element_state_get_name (state),
2922 gst_element_state_get_name (next));
2929 GST_OBJECT_LOCK (element);
2930 result = GST_STATE_RETURN (element);
2931 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2932 "element is already in the %s state",
2933 gst_element_state_get_name (state));
2934 GST_OBJECT_UNLOCK (element);
2941 * gst_element_get_factory:
2942 * @element: a #GstElement to request the element factory of.
2944 * Retrieves the factory that was used to create this element.
2946 * Returns: (transfer none): the #GstElementFactory used for creating this
2947 * element. no refcounting is needed.
2950 gst_element_get_factory (GstElement * element)
2952 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2954 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2958 gst_element_dispose (GObject * object)
2960 GstElement *element = GST_ELEMENT_CAST (object);
2963 GstElementClass *oclass;
2965 oclass = GST_ELEMENT_GET_CLASS (element);
2967 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2969 if (GST_STATE (element) != GST_STATE_NULL)
2972 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2973 "removing %d pads", g_list_length (element->pads));
2974 /* first we break all our links with the outside */
2975 while (element->pads && element->pads->data) {
2976 GstPad *pad = GST_PAD_CAST (element->pads->data);
2978 /* don't call _remove_pad with NULL */
2979 if (oclass->release_pad && GST_PAD_PAD_TEMPLATE (pad) &&
2980 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
2982 (oclass->release_pad) (element, GST_PAD_CAST (element->pads->data));
2984 gst_element_remove_pad (element, GST_PAD_CAST (element->pads->data));
2986 if (G_UNLIKELY (element->pads != NULL)) {
2987 g_critical ("could not remove pads from element %s",
2988 GST_STR_NULL (GST_OBJECT_NAME (object)));
2991 GST_OBJECT_LOCK (element);
2992 clock_p = &element->clock;
2993 bus_p = &element->bus;
2994 gst_object_replace ((GstObject **) clock_p, NULL);
2995 gst_object_replace ((GstObject **) bus_p, NULL);
2996 GST_OBJECT_UNLOCK (element);
2998 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
3000 G_OBJECT_CLASS (parent_class)->dispose (object);
3009 is_locked = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
3011 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
3013 "You need to explicitly set elements to the NULL state before\n"
3014 "dropping the final reference, to allow them to clean up.\n"
3015 "This problem may also be caused by a refcounting bug in the\n"
3016 "application or some element.\n",
3017 GST_OBJECT_NAME (element),
3018 gst_element_state_get_name (GST_STATE (element)),
3019 is_locked ? " (locked)" : "");
3025 gst_element_finalize (GObject * object)
3027 GstElement *element = GST_ELEMENT_CAST (object);
3029 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
3031 GST_STATE_LOCK (element);
3032 if (element->state_cond)
3033 g_cond_free (element->state_cond);
3034 element->state_cond = NULL;
3035 GST_STATE_UNLOCK (element);
3036 g_static_rec_mutex_free (element->state_lock);
3037 g_slice_free (GStaticRecMutex, element->state_lock);
3038 element->state_lock = NULL;
3040 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
3042 G_OBJECT_CLASS (parent_class)->finalize (object);
3045 #if !defined(GST_DISABLE_LOADSAVE) && !defined(GST_REMOVE_DEPRECATED)
3047 * gst_element_save_thyself:
3048 * @element: a #GstElement to save.
3049 * @parent: the xml parent node.
3051 * Saves the element as part of the given XML structure.
3053 * Returns: the new #xmlNodePtr.
3056 gst_element_save_thyself (GstObject * object, xmlNodePtr parent)
3059 GstElementClass *oclass;
3060 GParamSpec **specs, *spec;
3063 GValue value = { 0, };
3064 GstElement *element;
3066 g_return_val_if_fail (GST_IS_ELEMENT (object), parent);
3068 element = GST_ELEMENT_CAST (object);
3070 oclass = GST_ELEMENT_GET_CLASS (element);
3072 xmlNewChild (parent, NULL, (xmlChar *) "name",
3073 (xmlChar *) GST_ELEMENT_NAME (element));
3075 if (oclass->elementfactory != NULL) {
3076 GstElementFactory *factory = (GstElementFactory *) oclass->elementfactory;
3078 xmlNewChild (parent, NULL, (xmlChar *) "type",
3079 (xmlChar *) GST_PLUGIN_FEATURE (factory)->name);
3083 specs = g_object_class_list_properties (G_OBJECT_GET_CLASS (object), &nspecs);
3085 for (i = 0; i < nspecs; i++) {
3087 if (spec->flags & G_PARAM_READABLE) {
3091 g_value_init (&value, spec->value_type);
3093 g_object_get_property (G_OBJECT (element), spec->name, &value);
3094 param = xmlNewChild (parent, NULL, (xmlChar *) "param", NULL);
3095 xmlNewChild (param, NULL, (xmlChar *) "name", (xmlChar *) spec->name);
3097 if (G_IS_PARAM_SPEC_STRING (spec))
3098 contents = g_value_dup_string (&value);
3099 else if (G_IS_PARAM_SPEC_ENUM (spec))
3100 contents = g_strdup_printf ("%d", g_value_get_enum (&value));
3101 else if (G_IS_PARAM_SPEC_INT64 (spec))
3102 contents = g_strdup_printf ("%" G_GINT64_FORMAT,
3103 g_value_get_int64 (&value));
3104 else if (GST_VALUE_HOLDS_STRUCTURE (&value)) {
3105 if (g_value_get_boxed (&value) != NULL) {
3106 contents = g_strdup_value_contents (&value);
3108 contents = g_strdup ("NULL");
3111 contents = g_strdup_value_contents (&value);
3113 xmlNewChild (param, NULL, (xmlChar *) "value", (xmlChar *) contents);
3116 g_value_unset (&value);
3122 pads = g_list_last (GST_ELEMENT_PADS (element));
3125 GstPad *pad = GST_PAD_CAST (pads->data);
3127 /* figure out if it's a direct pad or a ghostpad */
3128 if (GST_ELEMENT_CAST (GST_OBJECT_PARENT (pad)) == element) {
3129 xmlNodePtr padtag = xmlNewChild (parent, NULL, (xmlChar *) "pad", NULL);
3131 gst_object_save_thyself (GST_OBJECT_CAST (pad), padtag);
3133 pads = g_list_previous (pads);
3140 gst_element_restore_thyself (GstObject * object, xmlNodePtr self)
3142 xmlNodePtr children;
3143 GstElement *element;
3145 gchar *value = NULL;
3147 element = GST_ELEMENT_CAST (object);
3148 g_return_if_fail (element != NULL);
3151 children = self->xmlChildrenNode;
3153 if (!strcmp ((char *) children->name, "param")) {
3154 xmlNodePtr child = children->xmlChildrenNode;
3157 if (!strcmp ((char *) child->name, "name")) {
3158 name = (gchar *) xmlNodeGetContent (child);
3159 } else if (!strcmp ((char *) child->name, "value")) {
3160 value = (gchar *) xmlNodeGetContent (child);
3162 child = child->next;
3164 /* FIXME: can this just be g_object_set ? */
3165 gst_util_set_object_arg (G_OBJECT (element), name, value);
3166 /* g_object_set (G_OBJECT (element), name, value, NULL); */
3170 children = children->next;
3174 children = self->xmlChildrenNode;
3176 if (!strcmp ((char *) children->name, "pad")) {
3177 gst_pad_load_and_link (children, GST_OBJECT_CAST (element));
3179 children = children->next;
3182 if (GST_OBJECT_CLASS (parent_class)->restore_thyself)
3183 (GST_OBJECT_CLASS (parent_class)->restore_thyself) (object, self);
3185 #endif /* GST_DISABLE_LOADSAVE */
3188 gst_element_set_bus_func (GstElement * element, GstBus * bus)
3192 g_return_if_fail (GST_IS_ELEMENT (element));
3194 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
3196 GST_OBJECT_LOCK (element);
3197 bus_p = &GST_ELEMENT_BUS (element);
3198 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
3199 GST_OBJECT_UNLOCK (element);
3203 * gst_element_set_bus:
3204 * @element: a #GstElement to set the bus of.
3205 * @bus: (transfer none): the #GstBus to set.
3207 * Sets the bus of the element. Increases the refcount on the bus.
3208 * For internal use only, unless you're testing elements.
3213 gst_element_set_bus (GstElement * element, GstBus * bus)
3215 GstElementClass *oclass;
3217 g_return_if_fail (GST_IS_ELEMENT (element));
3219 oclass = GST_ELEMENT_GET_CLASS (element);
3221 if (oclass->set_bus)
3222 oclass->set_bus (element, bus);
3226 * gst_element_get_bus:
3227 * @element: a #GstElement to get the bus of.
3229 * Returns the bus of the element. Note that only a #GstPipeline will provide a
3230 * bus for the application.
3232 * Returns: (transfer full): the element's #GstBus. unref after usage.
3237 gst_element_get_bus (GstElement * element)
3239 GstBus *result = NULL;
3241 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3243 GST_OBJECT_LOCK (element);
3244 if ((result = GST_ELEMENT_BUS (element)))
3245 gst_object_ref (result);
3246 GST_OBJECT_UNLOCK (element);
3248 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,