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));
339 oclass = GST_ELEMENT_GET_CLASS (element);
341 /* if the element implements a custom release function we call that, else we
342 * simply remove the pad from the element */
343 if (oclass->release_pad)
344 (oclass->release_pad) (element, pad);
346 gst_element_remove_pad (element, pad);
350 * gst_element_requires_clock:
351 * @element: a #GstElement to query
353 * Query if the element requires a clock.
355 * Returns: %TRUE if the element requires a clock
360 gst_element_requires_clock (GstElement * element)
364 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
366 result = (GST_ELEMENT_GET_CLASS (element)->set_clock != NULL);
372 * gst_element_provides_clock:
373 * @element: a #GstElement to query
375 * Query if the element provides a clock. A #GstClock provided by an
376 * element can be used as the global #GstClock for the pipeline.
377 * An element that can provide a clock is only required to do so in the PAUSED
378 * state, this means when it is fully negotiated and has allocated the resources
379 * to operate the clock.
381 * Returns: %TRUE if the element provides a clock
386 gst_element_provides_clock (GstElement * element)
390 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
392 result = (GST_ELEMENT_GET_CLASS (element)->provide_clock != NULL);
398 * gst_element_provide_clock:
399 * @element: a #GstElement to query
401 * Get the clock provided by the given element.
402 * <note>An element is only required to provide a clock in the PAUSED
403 * state. Some elements can provide a clock in other states.</note>
405 * Returns: (transfer full): the GstClock provided by the element or %NULL
406 * if no clock could be provided. Unref after usage.
411 gst_element_provide_clock (GstElement * element)
413 GstClock *result = NULL;
414 GstElementClass *oclass;
416 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
418 oclass = GST_ELEMENT_GET_CLASS (element);
420 if (oclass->provide_clock)
421 result = oclass->provide_clock (element);
427 * gst_element_set_clock:
428 * @element: a #GstElement to set the clock for.
429 * @clock: the #GstClock to set for the element.
431 * Sets the clock for the element. This function increases the
432 * refcount on the clock. Any previously set clock on the object
435 * Returns: %TRUE if the element accepted the clock. An element can refuse a
436 * clock when it, for example, is not able to slave its internal clock to the
437 * @clock or when it requires a specific clock to operate.
442 gst_element_set_clock (GstElement * element, GstClock * clock)
444 GstElementClass *oclass;
448 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
449 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
451 oclass = GST_ELEMENT_GET_CLASS (element);
453 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
455 if (oclass->set_clock)
456 res = oclass->set_clock (element, clock);
459 /* only update the clock pointer if the element accepted the clock */
460 GST_OBJECT_LOCK (element);
461 clock_p = &element->clock;
462 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
463 GST_OBJECT_UNLOCK (element);
469 * gst_element_get_clock:
470 * @element: a #GstElement to get the clock of.
472 * Gets the currently configured clock of the element. This is the clock as was
473 * last set with gst_element_set_clock().
475 * Returns: (transfer full): the #GstClock of the element. unref after usage.
480 gst_element_get_clock (GstElement * element)
484 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
486 GST_OBJECT_LOCK (element);
487 if ((result = element->clock))
488 gst_object_ref (result);
489 GST_OBJECT_UNLOCK (element);
495 * gst_element_set_base_time:
496 * @element: a #GstElement.
497 * @time: the base time to set.
499 * Set the base time of an element. See gst_element_get_base_time().
504 gst_element_set_base_time (GstElement * element, GstClockTime time)
508 g_return_if_fail (GST_IS_ELEMENT (element));
510 GST_OBJECT_LOCK (element);
511 old = element->base_time;
512 element->base_time = time;
513 GST_OBJECT_UNLOCK (element);
515 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
516 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
517 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
521 * gst_element_get_base_time:
522 * @element: a #GstElement.
524 * Returns the base time of the element. The base time is the
525 * absolute time of the clock when this element was last put to
526 * PLAYING. Subtracting the base time from the clock time gives
527 * the running time of the element.
529 * Returns: the base time of the element.
534 gst_element_get_base_time (GstElement * element)
538 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
540 GST_OBJECT_LOCK (element);
541 result = element->base_time;
542 GST_OBJECT_UNLOCK (element);
548 * gst_element_set_start_time:
549 * @element: a #GstElement.
550 * @time: the base time to set.
552 * Set the start time of an element. The start time of the element is the
553 * running time of the element when it last went to the PAUSED state. In READY
554 * or after a flushing seek, it is set to 0.
556 * Toplevel elements like #GstPipeline will manage the start_time and
557 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
558 * on such a toplevel element will disable the distribution of the base_time to
559 * the children and can be useful if the application manages the base_time
560 * itself, for example if you want to synchronize capture from multiple
561 * pipelines, and you can also ensure that the pipelines have the same clock.
568 gst_element_set_start_time (GstElement * element, GstClockTime time)
572 g_return_if_fail (GST_IS_ELEMENT (element));
574 GST_OBJECT_LOCK (element);
575 old = GST_ELEMENT_START_TIME (element);
576 GST_ELEMENT_START_TIME (element) = time;
577 GST_OBJECT_UNLOCK (element);
579 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
580 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
581 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
585 * gst_element_get_start_time:
586 * @element: a #GstElement.
588 * Returns the start time of the element. The start time is the
589 * running time of the clock when this element was last put to PAUSED.
591 * Usually the start_time is managed by a toplevel element such as
596 * Returns: the start time of the element.
601 gst_element_get_start_time (GstElement * element)
605 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
607 GST_OBJECT_LOCK (element);
608 result = GST_ELEMENT_START_TIME (element);
609 GST_OBJECT_UNLOCK (element);
615 * gst_element_is_indexable:
616 * @element: a #GstElement.
618 * Queries if the element can be indexed.
620 * Returns: TRUE if the element can be indexed.
625 gst_element_is_indexable (GstElement * element)
629 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
631 result = (GST_ELEMENT_GET_CLASS (element)->set_index != NULL);
637 * gst_element_set_index:
638 * @element: a #GstElement.
639 * @index: (transfer none): a #GstIndex.
641 * Set @index on the element. The refcount of the index
642 * will be increased, any previously set index is unreffed.
647 gst_element_set_index (GstElement * element, GstIndex * index)
649 GstElementClass *oclass;
651 g_return_if_fail (GST_IS_ELEMENT (element));
652 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
654 oclass = GST_ELEMENT_GET_CLASS (element);
656 if (oclass->set_index)
657 oclass->set_index (element, index);
661 * gst_element_get_index:
662 * @element: a #GstElement.
664 * Gets the index from the element.
666 * Returns: (transfer full): a #GstIndex or %NULL when no index was set on the
667 * element. unref after usage.
672 gst_element_get_index (GstElement * element)
674 GstElementClass *oclass;
675 GstIndex *result = NULL;
677 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
679 oclass = GST_ELEMENT_GET_CLASS (element);
681 if (oclass->get_index)
682 result = oclass->get_index (element);
688 * gst_element_add_pad:
689 * @element: a #GstElement to add the pad to.
690 * @pad: (transfer full): the #GstPad to add to the element.
692 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
693 * see gst_object_set_parent() for refcounting information.
695 * Pads are not automatically activated so elements should perform the needed
696 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
697 * state. See gst_pad_set_active() for more information about activating pads.
699 * The pad and the element should be unlocked when calling this function.
701 * This function will emit the #GstElement::pad-added signal on the element.
703 * Returns: %TRUE if the pad could be added. This function can fail when
704 * a pad with the same name already existed or the pad already had another
710 gst_element_add_pad (GstElement * element, GstPad * pad)
715 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
716 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
718 /* locking pad to look at the name */
719 GST_OBJECT_LOCK (pad);
720 pad_name = g_strdup (GST_PAD_NAME (pad));
721 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
722 GST_STR_NULL (pad_name));
723 flushing = GST_PAD_IS_FLUSHING (pad);
724 GST_OBJECT_UNLOCK (pad);
726 /* then check to see if there's already a pad by that name here */
727 GST_OBJECT_LOCK (element);
728 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
731 /* try to set the pad's parent */
732 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
733 GST_OBJECT_CAST (element))))
736 /* check for flushing pads */
737 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
738 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
739 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
740 "use gst_pad_set_active(pad,TRUE) before adding it.",
741 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
743 GST_OBJECT_LOCK (pad);
744 GST_PAD_UNSET_FLUSHING (pad);
745 GST_OBJECT_UNLOCK (pad);
750 /* add it to the list */
751 switch (gst_pad_get_direction (pad)) {
753 element->srcpads = g_list_prepend (element->srcpads, pad);
754 element->numsrcpads++;
757 element->sinkpads = g_list_prepend (element->sinkpads, pad);
758 element->numsinkpads++;
763 element->pads = g_list_prepend (element->pads, pad);
765 element->pads_cookie++;
766 GST_OBJECT_UNLOCK (element);
768 /* emit the PAD_ADDED signal */
769 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
776 g_critical ("Padname %s is not unique in element %s, not adding",
777 pad_name, GST_ELEMENT_NAME (element));
778 GST_OBJECT_UNLOCK (element);
785 ("Pad %s already has parent when trying to add to element %s",
786 pad_name, GST_ELEMENT_NAME (element));
787 GST_OBJECT_UNLOCK (element);
793 GST_OBJECT_LOCK (pad);
795 ("Trying to add pad %s to element %s, but it has no direction",
796 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
797 GST_OBJECT_UNLOCK (pad);
798 GST_OBJECT_UNLOCK (element);
804 * gst_element_remove_pad:
805 * @element: a #GstElement to remove pad from.
806 * @pad: (transfer none): the #GstPad to remove from the element.
808 * Removes @pad from @element. @pad will be destroyed if it has not been
809 * referenced elsewhere using gst_object_unparent().
811 * This function is used by plugin developers and should not be used
812 * by applications. Pads that were dynamically requested from elements
813 * with gst_element_get_request_pad() should be released with the
814 * gst_element_release_request_pad() function instead.
816 * Pads are not automatically deactivated so elements should perform the needed
817 * steps to deactivate the pad in case this pad is removed in the PAUSED or
818 * PLAYING state. See gst_pad_set_active() for more information about
821 * The pad and the element should be unlocked when calling this function.
823 * This function will emit the #GstElement::pad-removed signal on the element.
825 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
826 * pad does not belong to the provided element.
831 gst_element_remove_pad (GstElement * element, GstPad * pad)
835 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
836 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
838 /* locking pad to look at the name and parent */
839 GST_OBJECT_LOCK (pad);
840 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
841 GST_STR_NULL (GST_PAD_NAME (pad)));
843 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
845 GST_OBJECT_UNLOCK (pad);
848 if ((peer = gst_pad_get_peer (pad))) {
849 /* window for MT unsafeness, someone else could unlink here
850 * and then we call unlink with wrong pads. The unlink
851 * function would catch this and safely return failed. */
852 if (GST_PAD_IS_SRC (pad))
853 gst_pad_unlink (pad, peer);
855 gst_pad_unlink (peer, pad);
857 gst_object_unref (peer);
860 GST_OBJECT_LOCK (element);
861 /* remove it from the list */
862 switch (gst_pad_get_direction (pad)) {
864 element->srcpads = g_list_remove (element->srcpads, pad);
865 element->numsrcpads--;
868 element->sinkpads = g_list_remove (element->sinkpads, pad);
869 element->numsinkpads--;
872 g_critical ("Removing pad without direction???");
875 element->pads = g_list_remove (element->pads, pad);
877 element->pads_cookie++;
878 GST_OBJECT_UNLOCK (element);
880 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
881 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
883 gst_object_unparent (GST_OBJECT_CAST (pad));
890 /* FIXME, locking order? */
891 GST_OBJECT_LOCK (element);
892 g_critical ("Padname %s:%s does not belong to element %s when removing",
893 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
894 GST_OBJECT_UNLOCK (element);
895 GST_OBJECT_UNLOCK (pad);
901 * gst_element_no_more_pads:
902 * @element: a #GstElement
904 * Use this function to signal that the element does not expect any more pads
905 * to show up in the current pipeline. This function should be called whenever
906 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
907 * pad templates use this in combination with autopluggers to figure out that
908 * the element is done initializing its pads.
910 * This function emits the #GstElement::no-more-pads signal.
915 gst_element_no_more_pads (GstElement * element)
917 g_return_if_fail (GST_IS_ELEMENT (element));
919 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
923 pad_compare_name (GstPad * pad1, const gchar * name)
927 GST_OBJECT_LOCK (pad1);
928 result = strcmp (GST_PAD_NAME (pad1), name);
929 GST_OBJECT_UNLOCK (pad1);
935 * gst_element_get_static_pad:
936 * @element: a #GstElement to find a static pad of.
937 * @name: the name of the static #GstPad to retrieve.
939 * Retrieves a pad from @element by name. This version only retrieves
940 * already-existing (i.e. 'static') pads.
942 * Returns: (transfer full): the requested #GstPad if found, otherwise %NULL.
948 gst_element_get_static_pad (GstElement * element, const gchar * name)
951 GstPad *result = NULL;
953 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
954 g_return_val_if_fail (name != NULL, NULL);
956 GST_OBJECT_LOCK (element);
958 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
960 result = GST_PAD_CAST (find->data);
961 gst_object_ref (result);
964 if (result == NULL) {
965 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
966 name, GST_ELEMENT_NAME (element));
968 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
969 GST_ELEMENT_NAME (element), name);
971 GST_OBJECT_UNLOCK (element);
977 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
978 const gchar * name, const GstCaps * caps)
980 GstPad *newpad = NULL;
981 GstElementClass *oclass;
983 oclass = GST_ELEMENT_GET_CLASS (element);
985 if (oclass->request_new_pad_full)
986 newpad = (oclass->request_new_pad_full) (element, templ, name, caps);
987 else if (oclass->request_new_pad)
988 newpad = (oclass->request_new_pad) (element, templ, name);
991 gst_object_ref (newpad);
997 * gst_element_get_request_pad:
998 * @element: a #GstElement to find a request pad of.
999 * @name: the name of the request #GstPad to retrieve.
1001 * Retrieves a pad from the element by name. This version only retrieves
1002 * request pads. The pad should be released with
1003 * gst_element_release_request_pad().
1005 * This method is slow and will be deprecated in the future. New code should
1006 * use gst_element_request_pad() with the requested template.
1008 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1009 * Release after usage.
1012 gst_element_get_request_pad (GstElement * element, const gchar * name)
1014 GstPadTemplate *templ = NULL;
1016 const gchar *req_name = NULL;
1017 gboolean templ_found = FALSE;
1020 gchar *str, *endptr = NULL;
1021 GstElementClass *class;
1023 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1024 g_return_val_if_fail (name != NULL, NULL);
1026 class = GST_ELEMENT_GET_CLASS (element);
1028 /* if the name contains a %, we assume it's the complete template name. Get
1029 * the template and try to get a pad */
1030 if (strstr (name, "%")) {
1031 templ = gst_element_class_get_request_pad_template (class, name);
1036 /* there is no % in the name, try to find a matching template */
1037 list = class->padtemplates;
1038 while (!templ_found && list) {
1039 templ = (GstPadTemplate *) list->data;
1040 if (templ->presence == GST_PAD_REQUEST) {
1041 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1042 templ->name_template);
1043 /* see if we find an exact match */
1044 if (strcmp (name, templ->name_template) == 0) {
1049 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1050 and %d and %u, occurring at the end of the name_template, are the only
1052 else if ((str = strchr (templ->name_template, '%'))
1053 && strncmp (templ->name_template, name,
1054 str - templ->name_template) == 0
1055 && strlen (name) > str - templ->name_template) {
1056 data = name + (str - templ->name_template);
1057 if (*(str + 1) == 'd') {
1061 tmp = strtol (data, &endptr, 10);
1062 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1068 } else if (*(str + 1) == 'u') {
1072 tmp = strtoul (data, &endptr, 10);
1073 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1093 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1099 * gst_element_request_pad:
1100 * @element: a #GstElement to find a request pad of.
1101 * @templ: a #GstPadTemplate of which we want a pad of.
1102 * @name: (transfer none) (allow-none): the name of the request #GstPad
1103 * to retrieve. Can be %NULL.
1104 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1105 * request. Can be %NULL.
1107 * Retrieves a request pad from the element according to the provided template.
1109 * If the @caps are specified and the element implements thew new
1110 * request_new_pad_full virtual method, the element will use them to select
1111 * which pad to create.
1113 * The pad should be released with gst_element_release_request_pad().
1115 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1116 * Release after usage.
1121 gst_element_request_pad (GstElement * element,
1122 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1124 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1125 g_return_val_if_fail (templ != NULL, NULL);
1127 return _gst_element_request_pad (element, templ, name, caps);
1131 * gst_element_get_pad:
1132 * @element: a #GstElement.
1133 * @name: the name of the pad to retrieve.
1135 * Retrieves a pad from @element by name. Tries gst_element_get_static_pad()
1136 * first, then gst_element_get_request_pad().
1138 * Deprecated: This function is deprecated as it's unclear if the reference
1139 * to the result pad should be released with gst_object_unref() in case of a static pad
1140 * or gst_element_release_request_pad() in case of a request pad.
1141 * Use gst_element_get_static_pad() or gst_element_get_request_pad() instead.
1143 * Returns: (transfer full): the #GstPad if found, otherwise %NULL. Unref or Release after usage,
1144 * depending on the type of the pad.
1146 #ifndef GST_REMOVE_DEPRECATED
1147 #ifdef GST_DISABLE_DEPRECATED
1148 GstPad *gst_element_get_pad (GstElement * element, const gchar * name);
1151 gst_element_get_pad (GstElement * element, const gchar * name)
1155 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1156 g_return_val_if_fail (name != NULL, NULL);
1158 pad = gst_element_get_static_pad (element, name);
1160 pad = gst_element_get_request_pad (element, name);
1164 #endif /* GST_REMOVE_DEPRECATED */
1166 static GstIteratorItem
1167 iterate_pad (GstIterator * it, GstPad * pad)
1169 gst_object_ref (pad);
1170 return GST_ITERATOR_ITEM_PASS;
1173 static GstIterator *
1174 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1176 GstIterator *result;
1178 GST_OBJECT_LOCK (element);
1179 gst_object_ref (element);
1180 result = gst_iterator_new_list (GST_TYPE_PAD,
1181 GST_OBJECT_GET_LOCK (element),
1182 &element->pads_cookie,
1185 (GstIteratorItemFunction) iterate_pad,
1186 (GstIteratorDisposeFunction) gst_object_unref);
1187 GST_OBJECT_UNLOCK (element);
1193 * gst_element_iterate_pads:
1194 * @element: a #GstElement to iterate pads of.
1196 * Retrieves an iterattor of @element's pads. The iterator should
1197 * be freed after usage.
1199 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1205 gst_element_iterate_pads (GstElement * element)
1207 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1209 return gst_element_iterate_pad_list (element, &element->pads);
1213 * gst_element_iterate_src_pads:
1214 * @element: a #GstElement.
1216 * Retrieves an iterator of @element's source pads.
1218 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1224 gst_element_iterate_src_pads (GstElement * element)
1226 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1228 return gst_element_iterate_pad_list (element, &element->srcpads);
1232 * gst_element_iterate_sink_pads:
1233 * @element: a #GstElement.
1235 * Retrieves an iterator of @element's sink pads.
1237 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1243 gst_element_iterate_sink_pads (GstElement * element)
1245 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1247 return gst_element_iterate_pad_list (element, &element->sinkpads);
1251 * gst_element_class_add_pad_template:
1252 * @klass: the #GstElementClass to add the pad template to.
1253 * @templ: (transfer none): a #GstPadTemplate to add to the element class.
1255 * Adds a padtemplate to an element class. This is mainly used in the _base_init
1256 * functions of classes.
1259 gst_element_class_add_pad_template (GstElementClass * klass,
1260 GstPadTemplate * templ)
1262 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1263 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1265 /* FIXME 0.11: allow replacing the pad templates by
1266 * calling this with the same name as an already existing pad
1267 * template. For this we _must_ _not_ ref the added pad template
1268 * a second time and _must_ document that this function takes
1269 * ownership of the pad template. Otherwise we will leak pad templates
1270 * or the caller unref's the pad template and it disappears */
1271 /* avoid registering pad templates with the same name */
1272 g_return_if_fail (gst_element_class_get_pad_template (klass,
1273 templ->name_template) == NULL);
1275 klass->padtemplates = g_list_append (klass->padtemplates,
1276 gst_object_ref (templ));
1277 klass->numpadtemplates++;
1281 gst_element_class_add_meta_data (GstElementClass * klass,
1282 const gchar * key, const gchar * value)
1284 if (!klass->meta_data) {
1285 /* FIXME: use a quark for "metadata" */
1286 klass->meta_data = gst_structure_empty_new ("metadata");
1289 gst_structure_set ((GstStructure *) klass->meta_data,
1290 key, G_TYPE_STRING, value, NULL);
1294 * gst_element_class_set_documentation_uri:
1295 * @klass: class to set details for
1296 * @uri: uri of element documentation
1298 * Set uri pointing to user documentation. Applications can use this to show
1299 * help for e.g. effects to users.
1304 gst_element_class_set_documentation_uri (GstElementClass * klass,
1307 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1309 gst_element_class_add_meta_data (klass, "doc-uri", uri);
1313 * gst_element_class_set_icon_name:
1314 * @klass: class to set details for
1315 * @name: name of an icon
1317 * Elements that bridge to certain other products can include an icon of that
1318 * used product. Application can show the icon in menus/selectors to help
1319 * identifying specific elements.
1324 gst_element_class_set_icon_name (GstElementClass * klass, const gchar * name)
1326 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1328 gst_element_class_add_meta_data (klass, "icon-name", name);
1331 /* FIXME-0.11: deprecate and remove gst_element_class_set_details*() */
1333 * gst_element_class_set_details:
1334 * @klass: class to set details for
1335 * @details: details to set
1337 * Sets the detailed information for a #GstElementClass.
1338 * <note>This function is for use in _base_init functions only.</note>
1340 * The @details are copied.
1342 * Deprecated: Use gst_element_class_set_details_simple() instead.
1344 #ifndef GST_REMOVE_DEPRECATED
1345 #ifdef GST_DISABLE_DEPRECATED
1346 void gst_element_class_set_details (GstElementClass * klass,
1347 const GstElementDetails * details);
1350 gst_element_class_set_details (GstElementClass * klass,
1351 const GstElementDetails * details)
1353 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1354 g_return_if_fail (GST_IS_ELEMENT_DETAILS (details));
1356 __gst_element_details_copy (&klass->details, details);
1361 * gst_element_class_set_details_simple:
1362 * @klass: class to set details for
1363 * @longname: The long English name of the element. E.g. "File Sink"
1364 * @classification: String describing the type of element, as an unordered list
1365 * separated with slashes ('/'). See draft-klass.txt of the design docs
1366 * for more details and common types. E.g: "Sink/File"
1367 * @description: Sentence describing the purpose of the element.
1368 * E.g: "Write stream to a file"
1369 * @author: Name and contact details of the author(s). Use \n to separate
1370 * multiple author details. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1372 * Sets the detailed information for a #GstElementClass. Simpler version of
1373 * gst_element_class_set_details() that generates less linker overhead.
1374 * <note>This function is for use in _base_init functions only.</note>
1376 * The detail parameter strings are copied into the #GstElementDetails for
1377 * the element class.
1382 gst_element_class_set_details_simple (GstElementClass * klass,
1383 const gchar * longname, const gchar * classification,
1384 const gchar * description, const gchar * author)
1386 const GstElementDetails details =
1387 GST_ELEMENT_DETAILS ((gchar *) longname, (gchar *) classification,
1388 (gchar *) description, (gchar *) author);
1390 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1392 __gst_element_details_copy (&klass->details, &details);
1396 * gst_element_class_get_pad_template_list:
1397 * @element_class: a #GstElementClass to get pad templates of.
1399 * Retrieves a list of the pad templates associated with @element_class. The
1400 * list must not be modified by the calling code.
1401 * <note>If you use this function in the #GInstanceInitFunc of an object class
1402 * that has subclasses, make sure to pass the g_class parameter of the
1403 * #GInstanceInitFunc here.</note>
1405 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1409 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1411 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1413 return element_class->padtemplates;
1417 * gst_element_class_get_pad_template:
1418 * @element_class: a #GstElementClass to get the pad template of.
1419 * @name: the name of the #GstPadTemplate to get.
1421 * Retrieves a padtemplate from @element_class with the given name.
1422 * <note>If you use this function in the #GInstanceInitFunc of an object class
1423 * that has subclasses, make sure to pass the g_class parameter of the
1424 * #GInstanceInitFunc here.</note>
1426 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1427 * if none was found. No unreferencing is necessary.
1430 gst_element_class_get_pad_template (GstElementClass *
1431 element_class, const gchar * name)
1435 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1436 g_return_val_if_fail (name != NULL, NULL);
1438 padlist = element_class->padtemplates;
1441 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1443 if (strcmp (padtempl->name_template, name) == 0)
1446 padlist = g_list_next (padlist);
1452 static GstPadTemplate *
1453 gst_element_class_get_request_pad_template (GstElementClass *
1454 element_class, const gchar * name)
1456 GstPadTemplate *tmpl;
1458 tmpl = gst_element_class_get_pad_template (element_class, name);
1459 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1465 /* get a random pad on element of the given direction.
1466 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1469 gst_element_get_random_pad (GstElement * element,
1470 gboolean need_linked, GstPadDirection dir)
1472 GstPad *result = NULL;
1475 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1479 GST_OBJECT_LOCK (element);
1480 pads = element->srcpads;
1483 GST_OBJECT_LOCK (element);
1484 pads = element->sinkpads;
1487 goto wrong_direction;
1489 for (; pads; pads = g_list_next (pads)) {
1490 GstPad *pad = GST_PAD_CAST (pads->data);
1492 GST_OBJECT_LOCK (pad);
1493 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1494 GST_DEBUG_PAD_NAME (pad));
1496 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1497 /* if we require a linked pad, and it is not linked, continue the
1499 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1500 GST_DEBUG_PAD_NAME (pad));
1501 GST_OBJECT_UNLOCK (pad);
1504 /* found a pad, stop search */
1505 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1506 GST_DEBUG_PAD_NAME (pad));
1507 GST_OBJECT_UNLOCK (pad);
1513 gst_object_ref (result);
1515 GST_OBJECT_UNLOCK (element);
1519 /* ERROR handling */
1522 g_warning ("unknown pad direction %d", dir);
1528 gst_element_default_send_event (GstElement * element, GstEvent * event)
1530 gboolean result = FALSE;
1533 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1534 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1535 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1538 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1539 "pushing %s event to random %s pad %s:%s",
1540 GST_EVENT_TYPE_NAME (event),
1541 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1542 GST_DEBUG_PAD_NAME (pad));
1544 result = gst_pad_push_event (pad, event);
1545 gst_object_unref (pad);
1547 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1548 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1554 * gst_element_send_event:
1555 * @element: a #GstElement to send the event to.
1556 * @event: (transfer full): the #GstEvent to send to the element.
1558 * Sends an event to an element. If the element doesn't implement an
1559 * event handler, the event will be pushed on a random linked sink pad for
1560 * upstream events or a random linked source pad for downstream events.
1562 * This function takes owership of the provided event so you should
1563 * gst_event_ref() it if you want to reuse the event after this call.
1565 * Returns: %TRUE if the event was handled.
1570 gst_element_send_event (GstElement * element, GstEvent * event)
1572 GstElementClass *oclass;
1573 gboolean result = FALSE;
1575 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1576 g_return_val_if_fail (event != NULL, FALSE);
1578 oclass = GST_ELEMENT_GET_CLASS (element);
1580 GST_STATE_LOCK (element);
1581 if (oclass->send_event) {
1582 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1583 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1584 result = oclass->send_event (element, event);
1586 result = gst_element_default_send_event (element, event);
1588 GST_STATE_UNLOCK (element);
1595 * @element: a #GstElement to send the event to.
1596 * @rate: The new playback rate
1597 * @format: The format of the seek values
1598 * @flags: The optional seek flags.
1599 * @cur_type: The type and flags for the new current position
1600 * @cur: The value of the new current position
1601 * @stop_type: The type and flags for the new stop position
1602 * @stop: The value of the new stop position
1604 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1605 * the parameters. The seek event is sent to the element using
1606 * gst_element_send_event().
1608 * Returns: %TRUE if the event was handled.
1613 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1614 GstSeekFlags flags, GstSeekType cur_type, gint64 cur,
1615 GstSeekType stop_type, gint64 stop)
1620 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1623 gst_event_new_seek (rate, format, flags, cur_type, cur, stop_type, stop);
1624 result = gst_element_send_event (element, event);
1630 * gst_element_get_query_types:
1631 * @element: a #GstElement to query
1633 * Get an array of query types from the element.
1634 * If the element doesn't implement a query types function,
1635 * the query will be forwarded to the peer of a random linked sink pad.
1637 * Returns: An array of #GstQueryType elements that should not
1638 * be freed or modified.
1642 const GstQueryType *
1643 gst_element_get_query_types (GstElement * element)
1645 GstElementClass *oclass;
1646 const GstQueryType *result = NULL;
1648 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1650 oclass = GST_ELEMENT_GET_CLASS (element);
1652 if (oclass->get_query_types) {
1653 result = oclass->get_query_types (element);
1655 GstPad *pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1658 GstPad *peer = gst_pad_get_peer (pad);
1661 result = gst_pad_get_query_types (peer);
1663 gst_object_unref (peer);
1665 gst_object_unref (pad);
1672 gst_element_default_query (GstElement * element, GstQuery * query)
1674 gboolean result = FALSE;
1677 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1679 result = gst_pad_query (pad, query);
1681 gst_object_unref (pad);
1683 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1685 GstPad *peer = gst_pad_get_peer (pad);
1688 result = gst_pad_query (peer, query);
1690 gst_object_unref (peer);
1692 gst_object_unref (pad);
1699 * gst_element_query:
1700 * @element: a #GstElement to perform the query on.
1701 * @query: (transfer none): the #GstQuery.
1703 * Performs a query on the given element.
1705 * For elements that don't implement a query handler, this function
1706 * forwards the query to a random srcpad or to the peer of a
1707 * random linked sinkpad of this element.
1709 * Please note that some queries might need a running pipeline to work.
1711 * Returns: TRUE if the query could be performed.
1716 gst_element_query (GstElement * element, GstQuery * query)
1718 GstElementClass *oclass;
1719 gboolean result = FALSE;
1721 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1722 g_return_val_if_fail (query != NULL, FALSE);
1724 oclass = GST_ELEMENT_GET_CLASS (element);
1726 if (oclass->query) {
1727 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1728 GST_ELEMENT_NAME (element));
1729 result = oclass->query (element, query);
1731 result = gst_element_default_query (element, query);
1737 * gst_element_post_message:
1738 * @element: a #GstElement posting the message
1739 * @message: (transfer full): a #GstMessage to post
1741 * Post a message on the element's #GstBus. This function takes ownership of the
1742 * message; if you want to access the message after this call, you should add an
1743 * additional reference before calling.
1745 * Returns: %TRUE if the message was successfully posted. The function returns
1746 * %FALSE if the element did not have a bus.
1751 gst_element_post_message (GstElement * element, GstMessage * message)
1754 gboolean result = FALSE;
1756 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1757 g_return_val_if_fail (message != NULL, FALSE);
1759 GST_OBJECT_LOCK (element);
1762 if (G_UNLIKELY (bus == NULL))
1765 gst_object_ref (bus);
1766 GST_OBJECT_UNLOCK (element);
1768 /* we release the element lock when posting the message so that any
1769 * (synchronous) message handlers can operate on the element */
1770 result = gst_bus_post (bus, message);
1771 gst_object_unref (bus);
1778 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1779 "not posting message %p: no bus", message);
1780 GST_OBJECT_UNLOCK (element);
1781 gst_message_unref (message);
1787 * _gst_element_error_printf:
1788 * @format: the printf-like format to use, or %NULL
1790 * This function is only used internally by the gst_element_error() macro.
1792 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1798 _gst_element_error_printf (const gchar * format, ...)
1808 va_start (args, format);
1809 buffer = g_strdup_vprintf (format, args);
1815 * gst_element_message_full:
1816 * @element: a #GstElement to send message from
1817 * @type: the #GstMessageType
1818 * @domain: the GStreamer GError domain this message belongs to
1819 * @code: the GError code belonging to the domain
1820 * @text: (allow-none) (transfer full): an allocated text string to be used
1821 * as a replacement for the default message connected to code,
1823 * @debug: (allow-none) (transfer full): an allocated debug message to be
1824 * used as a replacement for the default debugging information,
1826 * @file: the source code file where the error was generated
1827 * @function: the source code function where the error was generated
1828 * @line: the source code line where the error was generated
1830 * Post an error, warning or info message on the bus from inside an element.
1832 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1833 * #GST_MESSAGE_INFO.
1837 void gst_element_message_full
1838 (GstElement * element, GstMessageType type,
1839 GQuark domain, gint code, gchar * text,
1840 gchar * debug, const gchar * file, const gchar * function, gint line)
1842 GError *gerror = NULL;
1846 gboolean has_debug = TRUE;
1847 GstMessage *message = NULL;
1850 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1851 g_return_if_fail (GST_IS_ELEMENT (element));
1852 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1853 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1855 /* check if we send the given text or the default error text */
1856 if ((text == NULL) || (text[0] == 0)) {
1857 /* text could have come from g_strdup_printf (""); */
1859 sent_text = gst_error_get_message (domain, code);
1863 /* construct a sent_debug with extra information from source */
1864 if ((debug == NULL) || (debug[0] == 0)) {
1865 /* debug could have come from g_strdup_printf (""); */
1869 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1871 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1872 file, line, function, name, debug);
1874 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1875 file, line, function, name);
1879 /* create gerror and post message */
1880 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1882 gerror = g_error_new_literal (domain, code, sent_text);
1885 case GST_MESSAGE_ERROR:
1887 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1889 case GST_MESSAGE_WARNING:
1890 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1893 case GST_MESSAGE_INFO:
1894 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1898 g_assert_not_reached ();
1901 gst_element_post_message (element, message);
1903 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1904 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1907 g_error_free (gerror);
1908 g_free (sent_debug);
1913 * gst_element_is_locked_state:
1914 * @element: a #GstElement.
1916 * Checks if the state of an element is locked.
1917 * If the state of an element is locked, state changes of the parent don't
1918 * affect the element.
1919 * This way you can leave currently unused elements inside bins. Just lock their
1920 * state before changing the state from #GST_STATE_NULL.
1924 * Returns: TRUE, if the element's state is locked.
1927 gst_element_is_locked_state (GstElement * element)
1931 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1933 GST_OBJECT_LOCK (element);
1934 result = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1935 GST_OBJECT_UNLOCK (element);
1941 * gst_element_set_locked_state:
1942 * @element: a #GstElement
1943 * @locked_state: TRUE to lock the element's state
1945 * Locks the state of an element, so state changes of the parent don't affect
1946 * this element anymore.
1950 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1951 * or the elements state-locking needed no change.
1954 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1958 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1960 GST_OBJECT_LOCK (element);
1961 old = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1963 if (G_UNLIKELY (old == locked_state))
1967 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1968 GST_ELEMENT_NAME (element));
1969 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_LOCKED_STATE);
1971 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1972 GST_ELEMENT_NAME (element));
1973 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_LOCKED_STATE);
1975 GST_OBJECT_UNLOCK (element);
1981 GST_CAT_DEBUG (GST_CAT_STATES,
1982 "elements %s was already in locked state %d",
1983 GST_ELEMENT_NAME (element), old);
1984 GST_OBJECT_UNLOCK (element);
1991 * gst_element_sync_state_with_parent:
1992 * @element: a #GstElement.
1994 * Tries to change the state of the element to the same as its parent.
1995 * If this function returns FALSE, the state of element is undefined.
1997 * Returns: TRUE, if the element's state could be synced to the parent's state.
2002 gst_element_sync_state_with_parent (GstElement * element)
2006 GstStateChangeReturn ret;
2008 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
2010 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
2011 GstState parent_current, parent_pending;
2013 GST_OBJECT_LOCK (parent);
2014 parent_current = GST_STATE (parent);
2015 parent_pending = GST_STATE_PENDING (parent);
2016 GST_OBJECT_UNLOCK (parent);
2018 /* set to pending if there is one, else we set it to the current state of
2020 if (parent_pending != GST_STATE_VOID_PENDING)
2021 target = parent_pending;
2023 target = parent_current;
2025 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2026 "syncing state (%s) to parent %s %s (%s, %s)",
2027 gst_element_state_get_name (GST_STATE (element)),
2028 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
2029 gst_element_state_get_name (parent_current),
2030 gst_element_state_get_name (parent_pending));
2032 ret = gst_element_set_state (element, target);
2033 if (ret == GST_STATE_CHANGE_FAILURE)
2036 gst_object_unref (parent);
2040 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
2047 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2048 "syncing state failed (%s)",
2049 gst_element_state_change_return_get_name (ret));
2050 gst_object_unref (parent);
2056 static GstStateChangeReturn
2057 gst_element_get_state_func (GstElement * element,
2058 GstState * state, GstState * pending, GstClockTime timeout)
2060 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2061 GstState old_pending;
2063 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2064 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2066 GST_OBJECT_LOCK (element);
2067 ret = GST_STATE_RETURN (element);
2068 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2069 gst_element_state_change_return_get_name (ret));
2071 /* we got an error, report immediately */
2072 if (ret == GST_STATE_CHANGE_FAILURE)
2075 /* we got no_preroll, report immediatly */
2076 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2079 /* no need to wait async if we are not async */
2080 if (ret != GST_STATE_CHANGE_ASYNC)
2083 old_pending = GST_STATE_PENDING (element);
2084 if (old_pending != GST_STATE_VOID_PENDING) {
2085 GTimeVal *timeval, abstimeout;
2088 if (timeout != GST_CLOCK_TIME_NONE) {
2089 glong add = timeout / 1000;
2094 /* make timeout absolute */
2095 g_get_current_time (&abstimeout);
2096 g_time_val_add (&abstimeout, add);
2097 timeval = &abstimeout;
2101 /* get cookie to detect state changes during waiting */
2102 cookie = element->state_cookie;
2104 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2105 "waiting for element to commit state");
2107 /* we have a pending state change, wait for it to complete */
2108 if (!GST_STATE_TIMED_WAIT (element, timeval)) {
2109 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2110 /* timeout triggered */
2111 ret = GST_STATE_CHANGE_ASYNC;
2113 if (cookie != element->state_cookie)
2116 /* could be success or failure */
2117 if (old_pending == GST_STATE (element)) {
2118 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2119 ret = GST_STATE_CHANGE_SUCCESS;
2121 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2122 ret = GST_STATE_CHANGE_FAILURE;
2125 /* if nothing is pending anymore we can return SUCCESS */
2126 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2127 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2128 ret = GST_STATE_CHANGE_SUCCESS;
2134 *state = GST_STATE (element);
2136 *pending = GST_STATE_PENDING (element);
2138 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2139 "state current: %s, pending: %s, result: %s",
2140 gst_element_state_get_name (GST_STATE (element)),
2141 gst_element_state_get_name (GST_STATE_PENDING (element)),
2142 gst_element_state_change_return_get_name (ret));
2143 GST_OBJECT_UNLOCK (element);
2150 *state = GST_STATE_VOID_PENDING;
2152 *pending = GST_STATE_VOID_PENDING;
2154 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2156 GST_OBJECT_UNLOCK (element);
2158 return GST_STATE_CHANGE_FAILURE;
2163 * gst_element_get_state:
2164 * @element: a #GstElement to get the state of.
2165 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2167 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2168 * state. Can be %NULL.
2169 * @timeout: a #GstClockTime to specify the timeout for an async
2170 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2172 * Gets the state of the element.
2174 * For elements that performed an ASYNC state change, as reported by
2175 * gst_element_set_state(), this function will block up to the
2176 * specified timeout value for the state change to complete.
2177 * If the element completes the state change or goes into
2178 * an error, this function returns immediately with a return value of
2179 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2181 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2182 * returns the current and pending state immediately.
2184 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2185 * successfully changed its state but is not able to provide data yet.
2186 * This mostly happens for live sources that only produce data in
2187 * %GST_STATE_PLAYING. While the state change return is equivalent to
2188 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2189 * some sink elements might not be able to complete their state change because
2190 * an element is not producing data to complete the preroll. When setting the
2191 * element to playing, the preroll will complete and playback will start.
2193 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2194 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2195 * element is still performing a state change or
2196 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2200 GstStateChangeReturn
2201 gst_element_get_state (GstElement * element,
2202 GstState * state, GstState * pending, GstClockTime timeout)
2204 GstElementClass *oclass;
2205 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2207 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2209 oclass = GST_ELEMENT_GET_CLASS (element);
2211 if (oclass->get_state)
2212 result = (oclass->get_state) (element, state, pending, timeout);
2218 * gst_element_abort_state:
2219 * @element: a #GstElement to abort the state of.
2221 * Abort the state change of the element. This function is used
2222 * by elements that do asynchronous state changes and find out
2223 * something is wrong.
2225 * This function should be called with the STATE_LOCK held.
2230 gst_element_abort_state (GstElement * element)
2234 #ifndef GST_DISABLE_GST_DEBUG
2238 g_return_if_fail (GST_IS_ELEMENT (element));
2240 GST_OBJECT_LOCK (element);
2241 pending = GST_STATE_PENDING (element);
2243 if (pending == GST_STATE_VOID_PENDING ||
2244 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2245 goto nothing_aborted;
2247 #ifndef GST_DISABLE_GST_DEBUG
2248 old_state = GST_STATE (element);
2250 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2251 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2252 gst_element_state_get_name (pending));
2256 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2258 GST_STATE_BROADCAST (element);
2259 GST_OBJECT_UNLOCK (element);
2265 GST_OBJECT_UNLOCK (element);
2271 * gst_element_continue_state:
2272 * @element: a #GstElement to continue the state change of.
2273 * @ret: The previous state return value
2275 * Commit the state change of the element and proceed to the next
2276 * pending state if any. This function is used
2277 * by elements that do asynchronous state changes.
2278 * The core will normally call this method automatically when an
2279 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2281 * If after calling this method the element still has not reached
2282 * the pending state, the next state change is performed.
2284 * This method is used internally and should normally not be called by plugins
2287 * Returns: The result of the commit state change.
2291 GstStateChangeReturn
2292 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2294 GstStateChangeReturn old_ret;
2295 GstState old_state, old_next;
2296 GstState current, next, pending;
2297 GstMessage *message;
2298 GstStateChange transition;
2300 GST_OBJECT_LOCK (element);
2301 old_ret = GST_STATE_RETURN (element);
2302 GST_STATE_RETURN (element) = ret;
2303 pending = GST_STATE_PENDING (element);
2305 /* check if there is something to commit */
2306 if (pending == GST_STATE_VOID_PENDING)
2307 goto nothing_pending;
2309 old_state = GST_STATE (element);
2310 /* this is the state we should go to next */
2311 old_next = GST_STATE_NEXT (element);
2312 /* update current state */
2313 current = GST_STATE (element) = old_next;
2315 /* see if we reached the final state */
2316 if (pending == current)
2319 next = GST_STATE_GET_NEXT (current, pending);
2320 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2322 GST_STATE_NEXT (element) = next;
2324 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2325 GST_OBJECT_UNLOCK (element);
2327 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2328 "committing state from %s to %s, pending %s, next %s",
2329 gst_element_state_get_name (old_state),
2330 gst_element_state_get_name (old_next),
2331 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2333 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2334 old_state, old_next, pending);
2335 gst_element_post_message (element, message);
2337 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2338 "continue state change %s to %s, final %s",
2339 gst_element_state_get_name (current),
2340 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2342 ret = gst_element_change_state (element, transition);
2348 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2349 GST_OBJECT_UNLOCK (element);
2354 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2355 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2357 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2358 "completed state change to %s", gst_element_state_get_name (pending));
2359 GST_OBJECT_UNLOCK (element);
2361 /* don't post silly messages with the same state. This can happen
2362 * when an element state is changed to what it already was. For bins
2363 * this can be the result of a lost state, which we check with the
2364 * previous return value.
2365 * We do signal the cond though as a _get_state() might be blocking
2367 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC) {
2368 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2369 "posting state-changed %s to %s",
2370 gst_element_state_get_name (old_state),
2371 gst_element_state_get_name (old_next));
2373 gst_message_new_state_changed (GST_OBJECT_CAST (element), old_state,
2374 old_next, GST_STATE_VOID_PENDING);
2375 gst_element_post_message (element, message);
2378 GST_STATE_BROADCAST (element);
2385 * gst_element_lost_state_full:
2386 * @element: a #GstElement the state is lost of
2387 * @new_base_time: if a new base time should be distributed
2389 * Brings the element to the lost state. The current state of the
2390 * element is copied to the pending state so that any call to
2391 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2393 * An ASYNC_START message is posted with indication to distribute a new
2394 * base_time to the element when @new_base_time is %TRUE.
2395 * If the element was PLAYING, it will go to PAUSED. The element
2396 * will be restored to its PLAYING state by the parent pipeline when it
2399 * This is mostly used for elements that lost their preroll buffer
2400 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2401 * they will go to their pending state again when a new preroll buffer is
2402 * queued. This function can only be called when the element is currently
2403 * not in error or an async state change.
2405 * This function is used internally and should normally not be called from
2406 * plugins or applications.
2413 gst_element_lost_state_full (GstElement * element, gboolean new_base_time)
2415 GstState old_state, new_state;
2416 GstMessage *message;
2418 g_return_if_fail (GST_IS_ELEMENT (element));
2420 GST_OBJECT_LOCK (element);
2421 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2424 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2425 goto only_async_start;
2427 old_state = GST_STATE (element);
2429 /* when we were PLAYING, the new state is PAUSED. We will also not
2430 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2431 * when we preroll. */
2432 if (old_state > GST_STATE_PAUSED)
2433 new_state = GST_STATE_PAUSED;
2435 new_state = old_state;
2437 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2438 "lost state of %s to %s", gst_element_state_get_name (old_state),
2439 gst_element_state_get_name (new_state));
2441 GST_STATE (element) = new_state;
2442 GST_STATE_NEXT (element) = new_state;
2443 GST_STATE_PENDING (element) = new_state;
2444 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2446 GST_ELEMENT_START_TIME (element) = 0;
2447 GST_OBJECT_UNLOCK (element);
2449 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2450 new_state, new_state, new_state);
2451 gst_element_post_message (element, message);
2454 gst_message_new_async_start (GST_OBJECT_CAST (element), new_base_time);
2455 gst_element_post_message (element, message);
2461 GST_OBJECT_UNLOCK (element);
2466 GST_OBJECT_UNLOCK (element);
2468 message = gst_message_new_async_start (GST_OBJECT_CAST (element), TRUE);
2469 gst_element_post_message (element, message);
2475 * gst_element_lost_state:
2476 * @element: a #GstElement the state is lost of
2478 * Brings the element to the lost state. This function calls
2479 * gst_element_lost_state_full() with the new_base_time set to %TRUE.
2481 * This function is used internally and should normally not be called from
2482 * plugins or applications.
2487 gst_element_lost_state (GstElement * element)
2489 gst_element_lost_state_full (element, TRUE);
2493 * gst_element_set_state:
2494 * @element: a #GstElement to change state of.
2495 * @state: the element's new #GstState.
2497 * Sets the state of the element. This function will try to set the
2498 * requested state by going through all the intermediary states and calling
2499 * the class's state change function for each.
2501 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2502 * element will perform the remainder of the state change asynchronously in
2504 * An application can use gst_element_get_state() to wait for the completion
2505 * of the state change or it can wait for a state change message on the bus.
2507 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2508 * #GST_STATE_CHANGE_ASYNC.
2510 * Returns: Result of the state change using #GstStateChangeReturn.
2514 GstStateChangeReturn
2515 gst_element_set_state (GstElement * element, GstState state)
2517 GstElementClass *oclass;
2518 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2520 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2522 oclass = GST_ELEMENT_GET_CLASS (element);
2524 if (oclass->set_state)
2525 result = (oclass->set_state) (element, state);
2531 * default set state function, calculates the next state based
2532 * on current state and calls the change_state function
2534 static GstStateChangeReturn
2535 gst_element_set_state_func (GstElement * element, GstState state)
2537 GstState current, next, old_pending;
2538 GstStateChangeReturn ret;
2539 GstStateChange transition;
2540 GstStateChangeReturn old_ret;
2542 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2544 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2545 gst_element_state_get_name (state));
2547 /* state lock is taken to protect the set_state() and get_state()
2548 * procedures, it does not lock any variables. */
2549 GST_STATE_LOCK (element);
2551 /* now calculate how to get to the new state */
2552 GST_OBJECT_LOCK (element);
2553 old_ret = GST_STATE_RETURN (element);
2554 /* previous state change returned an error, remove all pending
2555 * and next states */
2556 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2557 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2558 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2559 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2562 current = GST_STATE (element);
2563 next = GST_STATE_NEXT (element);
2564 old_pending = GST_STATE_PENDING (element);
2566 /* this is the (new) state we should go to. TARGET is the last state we set on
2568 if (state != GST_STATE_TARGET (element)) {
2569 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2570 "setting target state to %s", gst_element_state_get_name (state));
2571 GST_STATE_TARGET (element) = state;
2572 /* increment state cookie so that we can track each state change. We only do
2573 * this if this is actually a new state change. */
2574 element->state_cookie++;
2576 GST_STATE_PENDING (element) = state;
2578 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2579 "current %s, old_pending %s, next %s, old return %s",
2580 gst_element_state_get_name (current),
2581 gst_element_state_get_name (old_pending),
2582 gst_element_state_get_name (next),
2583 gst_element_state_change_return_get_name (old_ret));
2585 /* if the element was busy doing a state change, we just update the
2586 * target state, it'll get to it async then. */
2587 if (old_pending != GST_STATE_VOID_PENDING) {
2588 /* upwards state change will happen ASYNC */
2589 if (old_pending <= state)
2591 /* element is going to this state already */
2592 else if (next == state)
2594 /* element was performing an ASYNC upward state change and
2595 * we request to go downward again. Start from the next pending
2597 else if (next > state
2598 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2602 next = GST_STATE_GET_NEXT (current, state);
2603 /* now we store the next state */
2604 GST_STATE_NEXT (element) = next;
2605 /* mark busy, we need to check that there is actually a state change
2606 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2607 * the default element change_state function has no way to know what the
2608 * old value was... could consider this a FIXME...*/
2609 if (current != next)
2610 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2612 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2614 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2615 "%s: setting state from %s to %s",
2616 (next != state ? "intermediate" : "final"),
2617 gst_element_state_get_name (current), gst_element_state_get_name (next));
2619 /* now signal any waiters, they will error since the cookie was incremented */
2620 GST_STATE_BROADCAST (element);
2622 GST_OBJECT_UNLOCK (element);
2624 ret = gst_element_change_state (element, transition);
2626 GST_STATE_UNLOCK (element);
2628 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2629 gst_element_state_change_return_get_name (ret));
2635 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2636 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2637 "element was busy with async state change");
2638 GST_OBJECT_UNLOCK (element);
2640 GST_STATE_UNLOCK (element);
2642 return GST_STATE_CHANGE_ASYNC;
2647 * gst_element_change_state:
2648 * @element: a #GstElement
2649 * @transition: the requested transition
2651 * Perform @transition on @element.
2653 * This function must be called with STATE_LOCK held and is mainly used
2656 * Returns: the #GstStateChangeReturn of the state transition.
2658 GstStateChangeReturn
2659 gst_element_change_state (GstElement * element, GstStateChange transition)
2661 GstElementClass *oclass;
2662 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2664 oclass = GST_ELEMENT_GET_CLASS (element);
2666 /* call the state change function so it can set the state */
2667 if (oclass->change_state)
2668 ret = (oclass->change_state) (element, transition);
2670 ret = GST_STATE_CHANGE_FAILURE;
2673 case GST_STATE_CHANGE_FAILURE:
2674 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2675 "have FAILURE change_state return");
2676 /* state change failure */
2677 gst_element_abort_state (element);
2679 case GST_STATE_CHANGE_ASYNC:
2683 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2684 "element will change state ASYNC");
2686 target = GST_STATE_TARGET (element);
2688 if (target > GST_STATE_READY)
2691 /* else we just continue the state change downwards */
2692 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2693 "forcing commit state %s <= %s",
2694 gst_element_state_get_name (target),
2695 gst_element_state_get_name (GST_STATE_READY));
2697 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2700 case GST_STATE_CHANGE_SUCCESS:
2701 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2702 "element changed state SUCCESS");
2703 /* we can commit the state now which will proceeed to
2705 ret = gst_element_continue_state (element, ret);
2707 case GST_STATE_CHANGE_NO_PREROLL:
2708 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2709 "element changed state NO_PREROLL");
2710 /* we can commit the state now which will proceeed to
2712 ret = gst_element_continue_state (element, ret);
2715 goto invalid_return;
2718 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2723 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2731 GST_OBJECT_LOCK (element);
2732 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2733 g_critical ("%s: unknown return value %d from a state change function",
2734 GST_ELEMENT_NAME (element), ret);
2736 /* we are in error now */
2737 ret = GST_STATE_CHANGE_FAILURE;
2738 GST_STATE_RETURN (element) = ret;
2739 GST_OBJECT_UNLOCK (element);
2745 /* gst_iterator_fold functions for pads_activate
2746 * Note how we don't stop the iterator when we fail an activation. This is
2747 * probably a FIXME since when one pad activation fails, we don't want to
2748 * continue our state change. */
2750 activate_pads (GstPad * pad, GValue * ret, gboolean * active)
2752 if (!gst_pad_set_active (pad, *active))
2753 g_value_set_boolean (ret, FALSE);
2755 /* unref the object that was reffed for us by _fold */
2756 gst_object_unref (pad);
2760 /* set the caps on the pad to NULL */
2762 clear_caps (GstPad * pad, GValue * ret, gboolean * active)
2764 gst_pad_set_caps (pad, NULL);
2765 gst_object_unref (pad);
2769 /* returns false on error or early cutout (will never happen because the fold
2770 * function always returns TRUE, see FIXME above) of the fold, true if all
2771 * pads in @iter were (de)activated successfully. */
2773 iterator_activate_fold_with_resync (GstIterator * iter,
2774 GstIteratorFoldFunction func, gpointer user_data)
2776 GstIteratorResult ires;
2779 /* no need to unset this later, it's just a boolean */
2780 g_value_init (&ret, G_TYPE_BOOLEAN);
2781 g_value_set_boolean (&ret, TRUE);
2784 ires = gst_iterator_fold (iter, func, &ret, user_data);
2786 case GST_ITERATOR_RESYNC:
2787 /* need to reset the result again */
2788 g_value_set_boolean (&ret, TRUE);
2789 gst_iterator_resync (iter);
2791 case GST_ITERATOR_DONE:
2792 /* all pads iterated, return collected value */
2795 /* iterator returned _ERROR or premature end with _OK,
2796 * mark an error and exit */
2797 g_value_set_boolean (&ret, FALSE);
2802 /* return collected value */
2803 return g_value_get_boolean (&ret);
2806 /* is called with STATE_LOCK
2808 * Pads are activated from source pads to sinkpads.
2811 gst_element_pads_activate (GstElement * element, gboolean active)
2816 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2817 "pads_activate with active %d", active);
2819 iter = gst_element_iterate_src_pads (element);
2821 iterator_activate_fold_with_resync (iter,
2822 (GstIteratorFoldFunction) activate_pads, &active);
2823 gst_iterator_free (iter);
2824 if (G_UNLIKELY (!res))
2827 iter = gst_element_iterate_sink_pads (element);
2829 iterator_activate_fold_with_resync (iter,
2830 (GstIteratorFoldFunction) activate_pads, &active);
2831 gst_iterator_free (iter);
2832 if (G_UNLIKELY (!res))
2836 /* clear the caps on all pads, this should never fail */
2837 iter = gst_element_iterate_pads (element);
2839 iterator_activate_fold_with_resync (iter,
2840 (GstIteratorFoldFunction) clear_caps, &active);
2841 gst_iterator_free (iter);
2842 if (G_UNLIKELY (!res))
2846 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2847 "pads_activate successful");
2854 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2855 "source pads_activate failed");
2860 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2861 "sink pads_activate failed");
2866 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2867 "failed to clear caps on pads");
2872 /* is called with STATE_LOCK */
2873 static GstStateChangeReturn
2874 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2876 GstState state, next;
2877 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2880 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2882 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2883 next = GST_STATE_TRANSITION_NEXT (transition);
2885 /* if the element already is in the given state, we just return success */
2886 if (next == GST_STATE_VOID_PENDING || state == next)
2889 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2890 "default handler tries setting state from %s to %s (%04x)",
2891 gst_element_state_get_name (state),
2892 gst_element_state_get_name (next), transition);
2894 switch (transition) {
2895 case GST_STATE_CHANGE_NULL_TO_READY:
2897 case GST_STATE_CHANGE_READY_TO_PAUSED:
2898 if (!gst_element_pads_activate (element, TRUE)) {
2899 result = GST_STATE_CHANGE_FAILURE;
2902 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2904 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2906 case GST_STATE_CHANGE_PAUSED_TO_READY:
2907 case GST_STATE_CHANGE_READY_TO_NULL:
2908 /* deactivate pads in both cases, since they are activated on
2909 ready->paused but the element might not have made it to paused */
2910 if (!gst_element_pads_activate (element, FALSE)) {
2911 result = GST_STATE_CHANGE_FAILURE;
2913 gst_element_set_base_time (element, 0);
2916 /* In null state release the reference to the clock */
2917 GST_OBJECT_LOCK (element);
2918 clock_p = &element->clock;
2919 gst_object_replace ((GstObject **) clock_p, NULL);
2920 GST_OBJECT_UNLOCK (element);
2923 /* this will catch real but unhandled state changes;
2924 * can only be caused by:
2925 * - a new state was added
2926 * - somehow the element was asked to jump across an intermediate state
2928 g_warning ("Unhandled state change from %s to %s",
2929 gst_element_state_get_name (state),
2930 gst_element_state_get_name (next));
2937 GST_OBJECT_LOCK (element);
2938 result = GST_STATE_RETURN (element);
2939 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2940 "element is already in the %s state",
2941 gst_element_state_get_name (state));
2942 GST_OBJECT_UNLOCK (element);
2949 * gst_element_get_factory:
2950 * @element: a #GstElement to request the element factory of.
2952 * Retrieves the factory that was used to create this element.
2954 * Returns: (transfer none): the #GstElementFactory used for creating this
2955 * element. no refcounting is needed.
2958 gst_element_get_factory (GstElement * element)
2960 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2962 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2966 gst_element_dispose (GObject * object)
2968 GstElement *element = GST_ELEMENT_CAST (object);
2972 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2974 if (GST_STATE (element) != GST_STATE_NULL)
2977 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2978 "removing %d pads", g_list_length (element->pads));
2979 /* first we break all our links with the outside */
2980 while (element->pads && element->pads->data) {
2981 /* don't call _remove_pad with NULL */
2982 gst_element_remove_pad (element, GST_PAD_CAST (element->pads->data));
2984 if (G_UNLIKELY (element->pads != NULL)) {
2985 g_critical ("could not remove pads from element %s",
2986 GST_STR_NULL (GST_OBJECT_NAME (object)));
2989 GST_OBJECT_LOCK (element);
2990 clock_p = &element->clock;
2991 bus_p = &element->bus;
2992 gst_object_replace ((GstObject **) clock_p, NULL);
2993 gst_object_replace ((GstObject **) bus_p, NULL);
2994 GST_OBJECT_UNLOCK (element);
2996 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2998 G_OBJECT_CLASS (parent_class)->dispose (object);
3007 is_locked = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
3009 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
3011 "You need to explicitly set elements to the NULL state before\n"
3012 "dropping the final reference, to allow them to clean up.\n"
3013 "This problem may also be caused by a refcounting bug in the\n"
3014 "application or some element.\n",
3015 GST_OBJECT_NAME (element),
3016 gst_element_state_get_name (GST_STATE (element)),
3017 is_locked ? " (locked)" : "");
3023 gst_element_finalize (GObject * object)
3025 GstElement *element = GST_ELEMENT_CAST (object);
3027 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
3029 GST_STATE_LOCK (element);
3030 if (element->state_cond)
3031 g_cond_free (element->state_cond);
3032 element->state_cond = NULL;
3033 GST_STATE_UNLOCK (element);
3034 g_static_rec_mutex_free (element->state_lock);
3035 g_slice_free (GStaticRecMutex, element->state_lock);
3036 element->state_lock = NULL;
3038 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
3040 G_OBJECT_CLASS (parent_class)->finalize (object);
3043 #if !defined(GST_DISABLE_LOADSAVE) && !defined(GST_REMOVE_DEPRECATED)
3045 * gst_element_save_thyself:
3046 * @element: a #GstElement to save.
3047 * @parent: the xml parent node.
3049 * Saves the element as part of the given XML structure.
3051 * Returns: the new #xmlNodePtr.
3054 gst_element_save_thyself (GstObject * object, xmlNodePtr parent)
3057 GstElementClass *oclass;
3058 GParamSpec **specs, *spec;
3061 GValue value = { 0, };
3062 GstElement *element;
3064 g_return_val_if_fail (GST_IS_ELEMENT (object), parent);
3066 element = GST_ELEMENT_CAST (object);
3068 oclass = GST_ELEMENT_GET_CLASS (element);
3070 xmlNewChild (parent, NULL, (xmlChar *) "name",
3071 (xmlChar *) GST_ELEMENT_NAME (element));
3073 if (oclass->elementfactory != NULL) {
3074 GstElementFactory *factory = (GstElementFactory *) oclass->elementfactory;
3076 xmlNewChild (parent, NULL, (xmlChar *) "type",
3077 (xmlChar *) GST_PLUGIN_FEATURE (factory)->name);
3081 specs = g_object_class_list_properties (G_OBJECT_GET_CLASS (object), &nspecs);
3083 for (i = 0; i < nspecs; i++) {
3085 if (spec->flags & G_PARAM_READABLE) {
3089 g_value_init (&value, spec->value_type);
3091 g_object_get_property (G_OBJECT (element), spec->name, &value);
3092 param = xmlNewChild (parent, NULL, (xmlChar *) "param", NULL);
3093 xmlNewChild (param, NULL, (xmlChar *) "name", (xmlChar *) spec->name);
3095 if (G_IS_PARAM_SPEC_STRING (spec))
3096 contents = g_value_dup_string (&value);
3097 else if (G_IS_PARAM_SPEC_ENUM (spec))
3098 contents = g_strdup_printf ("%d", g_value_get_enum (&value));
3099 else if (G_IS_PARAM_SPEC_INT64 (spec))
3100 contents = g_strdup_printf ("%" G_GINT64_FORMAT,
3101 g_value_get_int64 (&value));
3102 else if (GST_VALUE_HOLDS_STRUCTURE (&value)) {
3103 if (g_value_get_boxed (&value) != NULL) {
3104 contents = g_strdup_value_contents (&value);
3106 contents = g_strdup ("NULL");
3109 contents = g_strdup_value_contents (&value);
3111 xmlNewChild (param, NULL, (xmlChar *) "value", (xmlChar *) contents);
3114 g_value_unset (&value);
3120 pads = g_list_last (GST_ELEMENT_PADS (element));
3123 GstPad *pad = GST_PAD_CAST (pads->data);
3125 /* figure out if it's a direct pad or a ghostpad */
3126 if (GST_ELEMENT_CAST (GST_OBJECT_PARENT (pad)) == element) {
3127 xmlNodePtr padtag = xmlNewChild (parent, NULL, (xmlChar *) "pad", NULL);
3129 gst_object_save_thyself (GST_OBJECT_CAST (pad), padtag);
3131 pads = g_list_previous (pads);
3138 gst_element_restore_thyself (GstObject * object, xmlNodePtr self)
3140 xmlNodePtr children;
3141 GstElement *element;
3143 gchar *value = NULL;
3145 element = GST_ELEMENT_CAST (object);
3146 g_return_if_fail (element != NULL);
3149 children = self->xmlChildrenNode;
3151 if (!strcmp ((char *) children->name, "param")) {
3152 xmlNodePtr child = children->xmlChildrenNode;
3155 if (!strcmp ((char *) child->name, "name")) {
3156 name = (gchar *) xmlNodeGetContent (child);
3157 } else if (!strcmp ((char *) child->name, "value")) {
3158 value = (gchar *) xmlNodeGetContent (child);
3160 child = child->next;
3162 /* FIXME: can this just be g_object_set ? */
3163 gst_util_set_object_arg (G_OBJECT (element), name, value);
3164 /* g_object_set (G_OBJECT (element), name, value, NULL); */
3168 children = children->next;
3172 children = self->xmlChildrenNode;
3174 if (!strcmp ((char *) children->name, "pad")) {
3175 gst_pad_load_and_link (children, GST_OBJECT_CAST (element));
3177 children = children->next;
3180 if (GST_OBJECT_CLASS (parent_class)->restore_thyself)
3181 (GST_OBJECT_CLASS (parent_class)->restore_thyself) (object, self);
3183 #endif /* GST_DISABLE_LOADSAVE */
3186 gst_element_set_bus_func (GstElement * element, GstBus * bus)
3190 g_return_if_fail (GST_IS_ELEMENT (element));
3192 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
3194 GST_OBJECT_LOCK (element);
3195 bus_p = &GST_ELEMENT_BUS (element);
3196 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
3197 GST_OBJECT_UNLOCK (element);
3201 * gst_element_set_bus:
3202 * @element: a #GstElement to set the bus of.
3203 * @bus: (transfer none): the #GstBus to set.
3205 * Sets the bus of the element. Increases the refcount on the bus.
3206 * For internal use only, unless you're testing elements.
3211 gst_element_set_bus (GstElement * element, GstBus * bus)
3213 GstElementClass *oclass;
3215 g_return_if_fail (GST_IS_ELEMENT (element));
3217 oclass = GST_ELEMENT_GET_CLASS (element);
3219 if (oclass->set_bus)
3220 oclass->set_bus (element, bus);
3224 * gst_element_get_bus:
3225 * @element: a #GstElement to get the bus of.
3227 * Returns the bus of the element. Note that only a #GstPipeline will provide a
3228 * bus for the application.
3230 * Returns: (transfer full): the element's #GstBus. unref after usage.
3235 gst_element_get_bus (GstElement * element)
3237 GstBus *result = NULL;
3239 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3241 GST_OBJECT_LOCK (element);
3242 if ((result = GST_ELEMENT_BUS (element)))
3243 gst_object_ref (result);
3244 GST_OBJECT_UNLOCK (element);
3246 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,