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, 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 &&
1083 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1089 * gst_element_request_pad:
1090 * @element: a #GstElement to find a request pad of.
1091 * @templ: a #GstPadTemplate of which we want a pad of.
1092 * @name: (transfer none) (allow-none): the name of the request #GstPad
1093 * to retrieve. Can be %NULL.
1094 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1095 * request. Can be %NULL.
1097 * Retrieves a request pad from the element according to the provided template.
1099 * If the @caps are specified and the element implements thew new
1100 * request_new_pad_full virtual method, the element will use them to select
1101 * which pad to create.
1103 * The pad should be released with gst_element_release_request_pad().
1105 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1106 * Release after usage.
1111 gst_element_request_pad (GstElement * element,
1112 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1114 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1115 g_return_val_if_fail (templ != NULL, NULL);
1117 return _gst_element_request_pad (element, templ, name, caps);
1121 * gst_element_get_pad:
1122 * @element: a #GstElement.
1123 * @name: the name of the pad to retrieve.
1125 * Retrieves a pad from @element by name. Tries gst_element_get_static_pad()
1126 * first, then gst_element_get_request_pad().
1128 * Deprecated: This function is deprecated as it's unclear if the reference
1129 * to the result pad should be released with gst_object_unref() in case of a static pad
1130 * or gst_element_release_request_pad() in case of a request pad.
1131 * Use gst_element_get_static_pad() or gst_element_get_request_pad() instead.
1133 * Returns: (transfer full): the #GstPad if found, otherwise %NULL. Unref or Release after usage,
1134 * depending on the type of the pad.
1136 #ifndef GST_REMOVE_DEPRECATED
1137 #ifdef GST_DISABLE_DEPRECATED
1138 GstPad *gst_element_get_pad (GstElement * element, const gchar * name);
1141 gst_element_get_pad (GstElement * element, const gchar * name)
1145 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1146 g_return_val_if_fail (name != NULL, NULL);
1148 pad = gst_element_get_static_pad (element, name);
1150 pad = gst_element_get_request_pad (element, name);
1154 #endif /* GST_REMOVE_DEPRECATED */
1156 static GstIteratorItem
1157 iterate_pad (GstIterator * it, GstPad * pad)
1159 gst_object_ref (pad);
1160 return GST_ITERATOR_ITEM_PASS;
1163 static GstIterator *
1164 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1166 GstIterator *result;
1168 GST_OBJECT_LOCK (element);
1169 gst_object_ref (element);
1170 result = gst_iterator_new_list (GST_TYPE_PAD,
1171 GST_OBJECT_GET_LOCK (element),
1172 &element->pads_cookie,
1175 (GstIteratorItemFunction) iterate_pad,
1176 (GstIteratorDisposeFunction) gst_object_unref);
1177 GST_OBJECT_UNLOCK (element);
1183 * gst_element_iterate_pads:
1184 * @element: a #GstElement to iterate pads of.
1186 * Retrieves an iterattor of @element's pads. The iterator should
1187 * be freed after usage.
1189 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1195 gst_element_iterate_pads (GstElement * element)
1197 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1199 return gst_element_iterate_pad_list (element, &element->pads);
1203 * gst_element_iterate_src_pads:
1204 * @element: a #GstElement.
1206 * Retrieves an iterator of @element's source pads.
1208 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1214 gst_element_iterate_src_pads (GstElement * element)
1216 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1218 return gst_element_iterate_pad_list (element, &element->srcpads);
1222 * gst_element_iterate_sink_pads:
1223 * @element: a #GstElement.
1225 * Retrieves an iterator of @element's sink pads.
1227 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1233 gst_element_iterate_sink_pads (GstElement * element)
1235 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1237 return gst_element_iterate_pad_list (element, &element->sinkpads);
1241 * gst_element_class_add_pad_template:
1242 * @klass: the #GstElementClass to add the pad template to.
1243 * @templ: (transfer none): a #GstPadTemplate to add to the element class.
1245 * Adds a padtemplate to an element class. This is mainly used in the _base_init
1246 * functions of classes.
1249 gst_element_class_add_pad_template (GstElementClass * klass,
1250 GstPadTemplate * templ)
1252 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1253 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1255 /* FIXME 0.11: allow replacing the pad templates by
1256 * calling this with the same name as an already existing pad
1257 * template. For this we _must_ _not_ ref the added pad template
1258 * a second time and _must_ document that this function takes
1259 * ownership of the pad template. Otherwise we will leak pad templates
1260 * or the caller unref's the pad template and it disappears */
1261 /* avoid registering pad templates with the same name */
1262 g_return_if_fail (gst_element_class_get_pad_template (klass,
1263 templ->name_template) == NULL);
1265 klass->padtemplates = g_list_append (klass->padtemplates,
1266 gst_object_ref (templ));
1267 klass->numpadtemplates++;
1271 gst_element_class_add_meta_data (GstElementClass * klass,
1272 const gchar * key, const gchar * value)
1274 if (!klass->meta_data) {
1275 /* FIXME: use a quark for "metadata" */
1276 klass->meta_data = gst_structure_empty_new ("metadata");
1279 gst_structure_set ((GstStructure *) klass->meta_data,
1280 key, G_TYPE_STRING, value, NULL);
1284 * gst_element_class_set_documentation_uri:
1285 * @klass: class to set details for
1286 * @uri: uri of element documentation
1288 * Set uri pointing to user documentation. Applications can use this to show
1289 * help for e.g. effects to users.
1294 gst_element_class_set_documentation_uri (GstElementClass * klass,
1297 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1299 gst_element_class_add_meta_data (klass, "doc-uri", uri);
1303 * gst_element_class_set_icon_name:
1304 * @klass: class to set details for
1305 * @name: name of an icon
1307 * Elements that bridge to certain other products can include an icon of that
1308 * used product. Application can show the icon in menus/selectors to help
1309 * identifying specific elements.
1314 gst_element_class_set_icon_name (GstElementClass * klass, const gchar * name)
1316 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1318 gst_element_class_add_meta_data (klass, "icon-name", name);
1321 /* FIXME-0.11: deprecate and remove gst_element_class_set_details*() */
1323 * gst_element_class_set_details:
1324 * @klass: class to set details for
1325 * @details: details to set
1327 * Sets the detailed information for a #GstElementClass.
1328 * <note>This function is for use in _base_init functions only.</note>
1330 * The @details are copied.
1332 * Deprecated: Use gst_element_class_set_details_simple() instead.
1334 #ifndef GST_REMOVE_DEPRECATED
1335 #ifdef GST_DISABLE_DEPRECATED
1337 gst_element_class_set_details (GstElementClass * klass,
1338 const GstElementDetails * details);
1341 gst_element_class_set_details (GstElementClass * klass,
1342 const GstElementDetails * details)
1344 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1345 g_return_if_fail (GST_IS_ELEMENT_DETAILS (details));
1347 __gst_element_details_copy (&klass->details, details);
1352 * gst_element_class_set_details_simple:
1353 * @klass: class to set details for
1354 * @longname: The long English name of the element. E.g. "File Sink"
1355 * @classification: String describing the type of element, as an unordered list
1356 * separated with slashes ('/'). See draft-klass.txt of the design docs
1357 * for more details and common types. E.g: "Sink/File"
1358 * @description: Sentence describing the purpose of the element.
1359 * E.g: "Write stream to a file"
1360 * @author: Name and contact details of the author(s). Use \n to separate
1361 * multiple author details. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1363 * Sets the detailed information for a #GstElementClass. Simpler version of
1364 * gst_element_class_set_details() that generates less linker overhead.
1365 * <note>This function is for use in _base_init functions only.</note>
1367 * The detail parameter strings are copied into the #GstElementDetails for
1368 * the element class.
1373 gst_element_class_set_details_simple (GstElementClass * klass,
1374 const gchar * longname, const gchar * classification,
1375 const gchar * description, const gchar * author)
1377 const GstElementDetails details =
1378 GST_ELEMENT_DETAILS ((gchar *) longname, (gchar *) classification,
1379 (gchar *) description, (gchar *) author);
1381 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1383 __gst_element_details_copy (&klass->details, &details);
1387 * gst_element_class_get_pad_template_list:
1388 * @element_class: a #GstElementClass to get pad templates of.
1390 * Retrieves a list of the pad templates associated with @element_class. The
1391 * list must not be modified by the calling code.
1392 * <note>If you use this function in the #GInstanceInitFunc of an object class
1393 * that has subclasses, make sure to pass the g_class parameter of the
1394 * #GInstanceInitFunc here.</note>
1396 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1400 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1402 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1404 return element_class->padtemplates;
1408 * gst_element_class_get_pad_template:
1409 * @element_class: a #GstElementClass to get the pad template of.
1410 * @name: the name of the #GstPadTemplate to get.
1412 * Retrieves a padtemplate from @element_class with the given name.
1413 * <note>If you use this function in the #GInstanceInitFunc of an object class
1414 * that has subclasses, make sure to pass the g_class parameter of the
1415 * #GInstanceInitFunc here.</note>
1417 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1418 * if none was found. No unreferencing is necessary.
1421 gst_element_class_get_pad_template (GstElementClass * element_class,
1426 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1427 g_return_val_if_fail (name != NULL, NULL);
1429 padlist = element_class->padtemplates;
1432 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1434 if (strcmp (padtempl->name_template, name) == 0)
1437 padlist = g_list_next (padlist);
1443 static GstPadTemplate *
1444 gst_element_class_get_request_pad_template (GstElementClass * element_class,
1447 GstPadTemplate *tmpl;
1449 tmpl = gst_element_class_get_pad_template (element_class, name);
1450 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1456 /* get a random pad on element of the given direction.
1457 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1460 gst_element_get_random_pad (GstElement * element, gboolean need_linked,
1461 GstPadDirection dir)
1463 GstPad *result = NULL;
1466 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1470 GST_OBJECT_LOCK (element);
1471 pads = element->srcpads;
1474 GST_OBJECT_LOCK (element);
1475 pads = element->sinkpads;
1478 goto wrong_direction;
1480 for (; pads; pads = g_list_next (pads)) {
1481 GstPad *pad = GST_PAD_CAST (pads->data);
1483 GST_OBJECT_LOCK (pad);
1484 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1485 GST_DEBUG_PAD_NAME (pad));
1487 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1488 /* if we require a linked pad, and it is not linked, continue the
1490 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1491 GST_DEBUG_PAD_NAME (pad));
1492 GST_OBJECT_UNLOCK (pad);
1495 /* found a pad, stop search */
1496 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1497 GST_DEBUG_PAD_NAME (pad));
1498 GST_OBJECT_UNLOCK (pad);
1504 gst_object_ref (result);
1506 GST_OBJECT_UNLOCK (element);
1510 /* ERROR handling */
1513 g_warning ("unknown pad direction %d", dir);
1519 gst_element_default_send_event (GstElement * element, GstEvent * event)
1521 gboolean result = FALSE;
1524 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1525 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1526 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1529 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1530 "pushing %s event to random %s pad %s:%s",
1531 GST_EVENT_TYPE_NAME (event),
1532 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1533 GST_DEBUG_PAD_NAME (pad));
1535 result = gst_pad_push_event (pad, event);
1536 gst_object_unref (pad);
1538 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1539 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1545 * gst_element_send_event:
1546 * @element: a #GstElement to send the event to.
1547 * @event: (transfer full): the #GstEvent to send to the element.
1549 * Sends an event to an element. If the element doesn't implement an
1550 * event handler, the event will be pushed on a random linked sink pad for
1551 * upstream events or a random linked source pad for downstream events.
1553 * This function takes owership of the provided event so you should
1554 * gst_event_ref() it if you want to reuse the event after this call.
1556 * Returns: %TRUE if the event was handled.
1561 gst_element_send_event (GstElement * element, GstEvent * event)
1563 GstElementClass *oclass;
1564 gboolean result = FALSE;
1566 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1567 g_return_val_if_fail (event != NULL, FALSE);
1569 oclass = GST_ELEMENT_GET_CLASS (element);
1571 GST_STATE_LOCK (element);
1572 if (oclass->send_event) {
1573 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1574 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1575 result = oclass->send_event (element, event);
1577 result = gst_element_default_send_event (element, event);
1579 GST_STATE_UNLOCK (element);
1586 * @element: a #GstElement to send the event to.
1587 * @rate: The new playback rate
1588 * @format: The format of the seek values
1589 * @flags: The optional seek flags.
1590 * @cur_type: The type and flags for the new current position
1591 * @cur: The value of the new current position
1592 * @stop_type: The type and flags for the new stop position
1593 * @stop: The value of the new stop position
1595 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1596 * the parameters. The seek event is sent to the element using
1597 * gst_element_send_event().
1599 * Returns: %TRUE if the event was handled.
1604 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1605 GstSeekFlags flags, GstSeekType cur_type, gint64 cur,
1606 GstSeekType stop_type, gint64 stop)
1611 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1614 gst_event_new_seek (rate, format, flags, cur_type, cur, stop_type, stop);
1615 result = gst_element_send_event (element, event);
1621 * gst_element_get_query_types:
1622 * @element: a #GstElement to query
1624 * Get an array of query types from the element.
1625 * If the element doesn't implement a query types function,
1626 * the query will be forwarded to the peer of a random linked sink pad.
1628 * Returns: An array of #GstQueryType elements that should not
1629 * be freed or modified.
1633 const GstQueryType *
1634 gst_element_get_query_types (GstElement * element)
1636 GstElementClass *oclass;
1637 const GstQueryType *result = NULL;
1639 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1641 oclass = GST_ELEMENT_GET_CLASS (element);
1643 if (oclass->get_query_types) {
1644 result = oclass->get_query_types (element);
1646 GstPad *pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1649 GstPad *peer = gst_pad_get_peer (pad);
1652 result = gst_pad_get_query_types (peer);
1654 gst_object_unref (peer);
1656 gst_object_unref (pad);
1663 gst_element_default_query (GstElement * element, GstQuery * query)
1665 gboolean result = FALSE;
1668 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1670 result = gst_pad_query (pad, query);
1672 gst_object_unref (pad);
1674 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1676 GstPad *peer = gst_pad_get_peer (pad);
1679 result = gst_pad_query (peer, query);
1681 gst_object_unref (peer);
1683 gst_object_unref (pad);
1690 * gst_element_query:
1691 * @element: a #GstElement to perform the query on.
1692 * @query: (transfer none): the #GstQuery.
1694 * Performs a query on the given element.
1696 * For elements that don't implement a query handler, this function
1697 * forwards the query to a random srcpad or to the peer of a
1698 * random linked sinkpad of this element.
1700 * Please note that some queries might need a running pipeline to work.
1702 * Returns: TRUE if the query could be performed.
1707 gst_element_query (GstElement * element, GstQuery * query)
1709 GstElementClass *oclass;
1710 gboolean result = FALSE;
1712 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1713 g_return_val_if_fail (query != NULL, FALSE);
1715 oclass = GST_ELEMENT_GET_CLASS (element);
1717 if (oclass->query) {
1718 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1719 GST_ELEMENT_NAME (element));
1720 result = oclass->query (element, query);
1722 result = gst_element_default_query (element, query);
1728 * gst_element_post_message:
1729 * @element: a #GstElement posting the message
1730 * @message: (transfer full): a #GstMessage to post
1732 * Post a message on the element's #GstBus. This function takes ownership of the
1733 * message; if you want to access the message after this call, you should add an
1734 * additional reference before calling.
1736 * Returns: %TRUE if the message was successfully posted. The function returns
1737 * %FALSE if the element did not have a bus.
1742 gst_element_post_message (GstElement * element, GstMessage * message)
1745 gboolean result = FALSE;
1747 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1748 g_return_val_if_fail (message != NULL, FALSE);
1750 GST_OBJECT_LOCK (element);
1753 if (G_UNLIKELY (bus == NULL))
1756 gst_object_ref (bus);
1757 GST_OBJECT_UNLOCK (element);
1759 /* we release the element lock when posting the message so that any
1760 * (synchronous) message handlers can operate on the element */
1761 result = gst_bus_post (bus, message);
1762 gst_object_unref (bus);
1769 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1770 "not posting message %p: no bus", message);
1771 GST_OBJECT_UNLOCK (element);
1772 gst_message_unref (message);
1778 * _gst_element_error_printf:
1779 * @format: the printf-like format to use, or %NULL
1781 * This function is only used internally by the gst_element_error() macro.
1783 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1789 _gst_element_error_printf (const gchar * format, ...)
1799 va_start (args, format);
1800 buffer = g_strdup_vprintf (format, args);
1806 * gst_element_message_full:
1807 * @element: a #GstElement to send message from
1808 * @type: the #GstMessageType
1809 * @domain: the GStreamer GError domain this message belongs to
1810 * @code: the GError code belonging to the domain
1811 * @text: (allow-none) (transfer full): an allocated text string to be used
1812 * as a replacement for the default message connected to code,
1814 * @debug: (allow-none) (transfer full): an allocated debug message to be
1815 * used as a replacement for the default debugging information,
1817 * @file: the source code file where the error was generated
1818 * @function: the source code function where the error was generated
1819 * @line: the source code line where the error was generated
1821 * Post an error, warning or info message on the bus from inside an element.
1823 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1824 * #GST_MESSAGE_INFO.
1828 void gst_element_message_full
1829 (GstElement * element, GstMessageType type,
1830 GQuark domain, gint code, gchar * text,
1831 gchar * debug, const gchar * file, const gchar * function, gint line)
1833 GError *gerror = NULL;
1837 gboolean has_debug = TRUE;
1838 GstMessage *message = NULL;
1841 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1842 g_return_if_fail (GST_IS_ELEMENT (element));
1843 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1844 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1846 /* check if we send the given text or the default error text */
1847 if ((text == NULL) || (text[0] == 0)) {
1848 /* text could have come from g_strdup_printf (""); */
1850 sent_text = gst_error_get_message (domain, code);
1854 /* construct a sent_debug with extra information from source */
1855 if ((debug == NULL) || (debug[0] == 0)) {
1856 /* debug could have come from g_strdup_printf (""); */
1860 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1862 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1863 file, line, function, name, debug);
1865 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1866 file, line, function, name);
1870 /* create gerror and post message */
1871 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1873 gerror = g_error_new_literal (domain, code, sent_text);
1876 case GST_MESSAGE_ERROR:
1878 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1880 case GST_MESSAGE_WARNING:
1881 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1884 case GST_MESSAGE_INFO:
1885 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1889 g_assert_not_reached ();
1892 gst_element_post_message (element, message);
1894 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1895 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1898 g_error_free (gerror);
1899 g_free (sent_debug);
1904 * gst_element_is_locked_state:
1905 * @element: a #GstElement.
1907 * Checks if the state of an element is locked.
1908 * If the state of an element is locked, state changes of the parent don't
1909 * affect the element.
1910 * This way you can leave currently unused elements inside bins. Just lock their
1911 * state before changing the state from #GST_STATE_NULL.
1915 * Returns: TRUE, if the element's state is locked.
1918 gst_element_is_locked_state (GstElement * element)
1922 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1924 GST_OBJECT_LOCK (element);
1925 result = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1926 GST_OBJECT_UNLOCK (element);
1932 * gst_element_set_locked_state:
1933 * @element: a #GstElement
1934 * @locked_state: TRUE to lock the element's state
1936 * Locks the state of an element, so state changes of the parent don't affect
1937 * this element anymore.
1941 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1942 * or the elements state-locking needed no change.
1945 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1949 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1951 GST_OBJECT_LOCK (element);
1952 old = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1954 if (G_UNLIKELY (old == locked_state))
1958 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1959 GST_ELEMENT_NAME (element));
1960 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_LOCKED_STATE);
1962 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1963 GST_ELEMENT_NAME (element));
1964 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_LOCKED_STATE);
1966 GST_OBJECT_UNLOCK (element);
1972 GST_CAT_DEBUG (GST_CAT_STATES, "elements %s was already in locked state %d",
1973 GST_ELEMENT_NAME (element), old);
1974 GST_OBJECT_UNLOCK (element);
1981 * gst_element_sync_state_with_parent:
1982 * @element: a #GstElement.
1984 * Tries to change the state of the element to the same as its parent.
1985 * If this function returns FALSE, the state of element is undefined.
1987 * Returns: TRUE, if the element's state could be synced to the parent's state.
1992 gst_element_sync_state_with_parent (GstElement * element)
1996 GstStateChangeReturn ret;
1998 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
2000 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
2001 GstState parent_current, parent_pending;
2003 GST_OBJECT_LOCK (parent);
2004 parent_current = GST_STATE (parent);
2005 parent_pending = GST_STATE_PENDING (parent);
2006 GST_OBJECT_UNLOCK (parent);
2008 /* set to pending if there is one, else we set it to the current state of
2010 if (parent_pending != GST_STATE_VOID_PENDING)
2011 target = parent_pending;
2013 target = parent_current;
2015 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2016 "syncing state (%s) to parent %s %s (%s, %s)",
2017 gst_element_state_get_name (GST_STATE (element)),
2018 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
2019 gst_element_state_get_name (parent_current),
2020 gst_element_state_get_name (parent_pending));
2022 ret = gst_element_set_state (element, target);
2023 if (ret == GST_STATE_CHANGE_FAILURE)
2026 gst_object_unref (parent);
2030 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
2037 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2038 "syncing state failed (%s)",
2039 gst_element_state_change_return_get_name (ret));
2040 gst_object_unref (parent);
2046 static GstStateChangeReturn
2047 gst_element_get_state_func (GstElement * element,
2048 GstState * state, GstState * pending, GstClockTime timeout)
2050 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2051 GstState old_pending;
2053 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2054 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2056 GST_OBJECT_LOCK (element);
2057 ret = GST_STATE_RETURN (element);
2058 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2059 gst_element_state_change_return_get_name (ret));
2061 /* we got an error, report immediately */
2062 if (ret == GST_STATE_CHANGE_FAILURE)
2065 /* we got no_preroll, report immediatly */
2066 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2069 /* no need to wait async if we are not async */
2070 if (ret != GST_STATE_CHANGE_ASYNC)
2073 old_pending = GST_STATE_PENDING (element);
2074 if (old_pending != GST_STATE_VOID_PENDING) {
2075 GTimeVal *timeval, abstimeout;
2078 if (timeout != GST_CLOCK_TIME_NONE) {
2079 glong add = timeout / 1000;
2084 /* make timeout absolute */
2085 g_get_current_time (&abstimeout);
2086 g_time_val_add (&abstimeout, add);
2087 timeval = &abstimeout;
2091 /* get cookie to detect state changes during waiting */
2092 cookie = element->state_cookie;
2094 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2095 "waiting for element to commit state");
2097 /* we have a pending state change, wait for it to complete */
2098 if (!GST_STATE_TIMED_WAIT (element, timeval)) {
2099 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2100 /* timeout triggered */
2101 ret = GST_STATE_CHANGE_ASYNC;
2103 if (cookie != element->state_cookie)
2106 /* could be success or failure */
2107 if (old_pending == GST_STATE (element)) {
2108 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2109 ret = GST_STATE_CHANGE_SUCCESS;
2111 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2112 ret = GST_STATE_CHANGE_FAILURE;
2115 /* if nothing is pending anymore we can return SUCCESS */
2116 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2117 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2118 ret = GST_STATE_CHANGE_SUCCESS;
2124 *state = GST_STATE (element);
2126 *pending = GST_STATE_PENDING (element);
2128 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2129 "state current: %s, pending: %s, result: %s",
2130 gst_element_state_get_name (GST_STATE (element)),
2131 gst_element_state_get_name (GST_STATE_PENDING (element)),
2132 gst_element_state_change_return_get_name (ret));
2133 GST_OBJECT_UNLOCK (element);
2140 *state = GST_STATE_VOID_PENDING;
2142 *pending = GST_STATE_VOID_PENDING;
2144 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2146 GST_OBJECT_UNLOCK (element);
2148 return GST_STATE_CHANGE_FAILURE;
2153 * gst_element_get_state:
2154 * @element: a #GstElement to get the state of.
2155 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2157 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2158 * state. Can be %NULL.
2159 * @timeout: a #GstClockTime to specify the timeout for an async
2160 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2162 * Gets the state of the element.
2164 * For elements that performed an ASYNC state change, as reported by
2165 * gst_element_set_state(), this function will block up to the
2166 * specified timeout value for the state change to complete.
2167 * If the element completes the state change or goes into
2168 * an error, this function returns immediately with a return value of
2169 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2171 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2172 * returns the current and pending state immediately.
2174 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2175 * successfully changed its state but is not able to provide data yet.
2176 * This mostly happens for live sources that only produce data in
2177 * %GST_STATE_PLAYING. While the state change return is equivalent to
2178 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2179 * some sink elements might not be able to complete their state change because
2180 * an element is not producing data to complete the preroll. When setting the
2181 * element to playing, the preroll will complete and playback will start.
2183 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2184 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2185 * element is still performing a state change or
2186 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2190 GstStateChangeReturn
2191 gst_element_get_state (GstElement * element,
2192 GstState * state, GstState * pending, GstClockTime timeout)
2194 GstElementClass *oclass;
2195 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2197 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2199 oclass = GST_ELEMENT_GET_CLASS (element);
2201 if (oclass->get_state)
2202 result = (oclass->get_state) (element, state, pending, timeout);
2208 * gst_element_abort_state:
2209 * @element: a #GstElement to abort the state of.
2211 * Abort the state change of the element. This function is used
2212 * by elements that do asynchronous state changes and find out
2213 * something is wrong.
2215 * This function should be called with the STATE_LOCK held.
2220 gst_element_abort_state (GstElement * element)
2224 #ifndef GST_DISABLE_GST_DEBUG
2228 g_return_if_fail (GST_IS_ELEMENT (element));
2230 GST_OBJECT_LOCK (element);
2231 pending = GST_STATE_PENDING (element);
2233 if (pending == GST_STATE_VOID_PENDING ||
2234 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2235 goto nothing_aborted;
2237 #ifndef GST_DISABLE_GST_DEBUG
2238 old_state = GST_STATE (element);
2240 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2241 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2242 gst_element_state_get_name (pending));
2246 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2248 GST_STATE_BROADCAST (element);
2249 GST_OBJECT_UNLOCK (element);
2255 GST_OBJECT_UNLOCK (element);
2261 * gst_element_continue_state:
2262 * @element: a #GstElement to continue the state change of.
2263 * @ret: The previous state return value
2265 * Commit the state change of the element and proceed to the next
2266 * pending state if any. This function is used
2267 * by elements that do asynchronous state changes.
2268 * The core will normally call this method automatically when an
2269 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2271 * If after calling this method the element still has not reached
2272 * the pending state, the next state change is performed.
2274 * This method is used internally and should normally not be called by plugins
2277 * Returns: The result of the commit state change.
2281 GstStateChangeReturn
2282 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2284 GstStateChangeReturn old_ret;
2285 GstState old_state, old_next;
2286 GstState current, next, pending;
2287 GstMessage *message;
2288 GstStateChange transition;
2290 GST_OBJECT_LOCK (element);
2291 old_ret = GST_STATE_RETURN (element);
2292 GST_STATE_RETURN (element) = ret;
2293 pending = GST_STATE_PENDING (element);
2295 /* check if there is something to commit */
2296 if (pending == GST_STATE_VOID_PENDING)
2297 goto nothing_pending;
2299 old_state = GST_STATE (element);
2300 /* this is the state we should go to next */
2301 old_next = GST_STATE_NEXT (element);
2302 /* update current state */
2303 current = GST_STATE (element) = old_next;
2305 /* see if we reached the final state */
2306 if (pending == current)
2309 next = GST_STATE_GET_NEXT (current, pending);
2310 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2312 GST_STATE_NEXT (element) = next;
2314 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2315 GST_OBJECT_UNLOCK (element);
2317 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2318 "committing state from %s to %s, pending %s, next %s",
2319 gst_element_state_get_name (old_state),
2320 gst_element_state_get_name (old_next),
2321 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2323 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2324 old_state, old_next, pending);
2325 gst_element_post_message (element, message);
2327 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2328 "continue state change %s to %s, final %s",
2329 gst_element_state_get_name (current),
2330 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2332 ret = gst_element_change_state (element, transition);
2338 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2339 GST_OBJECT_UNLOCK (element);
2344 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2345 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2347 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2348 "completed state change to %s", gst_element_state_get_name (pending));
2349 GST_OBJECT_UNLOCK (element);
2351 /* don't post silly messages with the same state. This can happen
2352 * when an element state is changed to what it already was. For bins
2353 * this can be the result of a lost state, which we check with the
2354 * previous return value.
2355 * We do signal the cond though as a _get_state() might be blocking
2357 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC) {
2358 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2359 "posting state-changed %s to %s",
2360 gst_element_state_get_name (old_state),
2361 gst_element_state_get_name (old_next));
2363 gst_message_new_state_changed (GST_OBJECT_CAST (element), old_state,
2364 old_next, GST_STATE_VOID_PENDING);
2365 gst_element_post_message (element, message);
2368 GST_STATE_BROADCAST (element);
2375 * gst_element_lost_state_full:
2376 * @element: a #GstElement the state is lost of
2377 * @new_base_time: if a new base time should be distributed
2379 * Brings the element to the lost state. The current state of the
2380 * element is copied to the pending state so that any call to
2381 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2383 * An ASYNC_START message is posted with indication to distribute a new
2384 * base_time to the element when @new_base_time is %TRUE.
2385 * If the element was PLAYING, it will go to PAUSED. The element
2386 * will be restored to its PLAYING state by the parent pipeline when it
2389 * This is mostly used for elements that lost their preroll buffer
2390 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2391 * they will go to their pending state again when a new preroll buffer is
2392 * queued. This function can only be called when the element is currently
2393 * not in error or an async state change.
2395 * This function is used internally and should normally not be called from
2396 * plugins or applications.
2403 gst_element_lost_state_full (GstElement * element, gboolean new_base_time)
2405 GstState old_state, new_state;
2406 GstMessage *message;
2408 g_return_if_fail (GST_IS_ELEMENT (element));
2410 GST_OBJECT_LOCK (element);
2411 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2414 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2415 goto only_async_start;
2417 old_state = GST_STATE (element);
2419 /* when we were PLAYING, the new state is PAUSED. We will also not
2420 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2421 * when we preroll. */
2422 if (old_state > GST_STATE_PAUSED)
2423 new_state = GST_STATE_PAUSED;
2425 new_state = old_state;
2427 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2428 "lost state of %s to %s", gst_element_state_get_name (old_state),
2429 gst_element_state_get_name (new_state));
2431 GST_STATE (element) = new_state;
2432 GST_STATE_NEXT (element) = new_state;
2433 GST_STATE_PENDING (element) = new_state;
2434 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2436 GST_ELEMENT_START_TIME (element) = 0;
2437 GST_OBJECT_UNLOCK (element);
2439 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2440 new_state, new_state, new_state);
2441 gst_element_post_message (element, message);
2444 gst_message_new_async_start (GST_OBJECT_CAST (element), new_base_time);
2445 gst_element_post_message (element, message);
2451 GST_OBJECT_UNLOCK (element);
2456 GST_OBJECT_UNLOCK (element);
2458 message = gst_message_new_async_start (GST_OBJECT_CAST (element), TRUE);
2459 gst_element_post_message (element, message);
2465 * gst_element_lost_state:
2466 * @element: a #GstElement the state is lost of
2468 * Brings the element to the lost state. This function calls
2469 * gst_element_lost_state_full() with the new_base_time set to %TRUE.
2471 * This function is used internally and should normally not be called from
2472 * plugins or applications.
2477 gst_element_lost_state (GstElement * element)
2479 gst_element_lost_state_full (element, TRUE);
2483 * gst_element_set_state:
2484 * @element: a #GstElement to change state of.
2485 * @state: the element's new #GstState.
2487 * Sets the state of the element. This function will try to set the
2488 * requested state by going through all the intermediary states and calling
2489 * the class's state change function for each.
2491 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2492 * element will perform the remainder of the state change asynchronously in
2494 * An application can use gst_element_get_state() to wait for the completion
2495 * of the state change or it can wait for a state change message on the bus.
2497 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2498 * #GST_STATE_CHANGE_ASYNC.
2500 * Returns: Result of the state change using #GstStateChangeReturn.
2504 GstStateChangeReturn
2505 gst_element_set_state (GstElement * element, GstState state)
2507 GstElementClass *oclass;
2508 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2510 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2512 oclass = GST_ELEMENT_GET_CLASS (element);
2514 if (oclass->set_state)
2515 result = (oclass->set_state) (element, state);
2521 * default set state function, calculates the next state based
2522 * on current state and calls the change_state function
2524 static GstStateChangeReturn
2525 gst_element_set_state_func (GstElement * element, GstState state)
2527 GstState current, next, old_pending;
2528 GstStateChangeReturn ret;
2529 GstStateChange transition;
2530 GstStateChangeReturn old_ret;
2532 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2534 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2535 gst_element_state_get_name (state));
2537 /* state lock is taken to protect the set_state() and get_state()
2538 * procedures, it does not lock any variables. */
2539 GST_STATE_LOCK (element);
2541 /* now calculate how to get to the new state */
2542 GST_OBJECT_LOCK (element);
2543 old_ret = GST_STATE_RETURN (element);
2544 /* previous state change returned an error, remove all pending
2545 * and next states */
2546 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2547 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2548 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2549 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2552 current = GST_STATE (element);
2553 next = GST_STATE_NEXT (element);
2554 old_pending = GST_STATE_PENDING (element);
2556 /* this is the (new) state we should go to. TARGET is the last state we set on
2558 if (state != GST_STATE_TARGET (element)) {
2559 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2560 "setting target state to %s", gst_element_state_get_name (state));
2561 GST_STATE_TARGET (element) = state;
2562 /* increment state cookie so that we can track each state change. We only do
2563 * this if this is actually a new state change. */
2564 element->state_cookie++;
2566 GST_STATE_PENDING (element) = state;
2568 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2569 "current %s, old_pending %s, next %s, old return %s",
2570 gst_element_state_get_name (current),
2571 gst_element_state_get_name (old_pending),
2572 gst_element_state_get_name (next),
2573 gst_element_state_change_return_get_name (old_ret));
2575 /* if the element was busy doing a state change, we just update the
2576 * target state, it'll get to it async then. */
2577 if (old_pending != GST_STATE_VOID_PENDING) {
2578 /* upwards state change will happen ASYNC */
2579 if (old_pending <= state)
2581 /* element is going to this state already */
2582 else if (next == state)
2584 /* element was performing an ASYNC upward state change and
2585 * we request to go downward again. Start from the next pending
2587 else if (next > state
2588 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2592 next = GST_STATE_GET_NEXT (current, state);
2593 /* now we store the next state */
2594 GST_STATE_NEXT (element) = next;
2595 /* mark busy, we need to check that there is actually a state change
2596 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2597 * the default element change_state function has no way to know what the
2598 * old value was... could consider this a FIXME...*/
2599 if (current != next)
2600 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2602 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2604 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2605 "%s: setting state from %s to %s",
2606 (next != state ? "intermediate" : "final"),
2607 gst_element_state_get_name (current), gst_element_state_get_name (next));
2609 /* now signal any waiters, they will error since the cookie was incremented */
2610 GST_STATE_BROADCAST (element);
2612 GST_OBJECT_UNLOCK (element);
2614 ret = gst_element_change_state (element, transition);
2616 GST_STATE_UNLOCK (element);
2618 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2619 gst_element_state_change_return_get_name (ret));
2625 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2626 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2627 "element was busy with async state change");
2628 GST_OBJECT_UNLOCK (element);
2630 GST_STATE_UNLOCK (element);
2632 return GST_STATE_CHANGE_ASYNC;
2637 * gst_element_change_state:
2638 * @element: a #GstElement
2639 * @transition: the requested transition
2641 * Perform @transition on @element.
2643 * This function must be called with STATE_LOCK held and is mainly used
2646 * Returns: the #GstStateChangeReturn of the state transition.
2648 GstStateChangeReturn
2649 gst_element_change_state (GstElement * element, GstStateChange transition)
2651 GstElementClass *oclass;
2652 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2654 oclass = GST_ELEMENT_GET_CLASS (element);
2656 /* call the state change function so it can set the state */
2657 if (oclass->change_state)
2658 ret = (oclass->change_state) (element, transition);
2660 ret = GST_STATE_CHANGE_FAILURE;
2663 case GST_STATE_CHANGE_FAILURE:
2664 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2665 "have FAILURE change_state return");
2666 /* state change failure */
2667 gst_element_abort_state (element);
2669 case GST_STATE_CHANGE_ASYNC:
2673 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2674 "element will change state ASYNC");
2676 target = GST_STATE_TARGET (element);
2678 if (target > GST_STATE_READY)
2681 /* else we just continue the state change downwards */
2682 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2683 "forcing commit state %s <= %s",
2684 gst_element_state_get_name (target),
2685 gst_element_state_get_name (GST_STATE_READY));
2687 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2690 case GST_STATE_CHANGE_SUCCESS:
2691 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2692 "element changed state SUCCESS");
2693 /* we can commit the state now which will proceeed to
2695 ret = gst_element_continue_state (element, ret);
2697 case GST_STATE_CHANGE_NO_PREROLL:
2698 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2699 "element changed state NO_PREROLL");
2700 /* we can commit the state now which will proceeed to
2702 ret = gst_element_continue_state (element, ret);
2705 goto invalid_return;
2708 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2713 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2721 GST_OBJECT_LOCK (element);
2722 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2723 g_critical ("%s: unknown return value %d from a state change function",
2724 GST_ELEMENT_NAME (element), ret);
2726 /* we are in error now */
2727 ret = GST_STATE_CHANGE_FAILURE;
2728 GST_STATE_RETURN (element) = ret;
2729 GST_OBJECT_UNLOCK (element);
2735 /* gst_iterator_fold functions for pads_activate
2736 * Note how we don't stop the iterator when we fail an activation. This is
2737 * probably a FIXME since when one pad activation fails, we don't want to
2738 * continue our state change. */
2740 activate_pads (GstPad * pad, GValue * ret, gboolean * active)
2742 if (!gst_pad_set_active (pad, *active))
2743 g_value_set_boolean (ret, FALSE);
2745 /* unref the object that was reffed for us by _fold */
2746 gst_object_unref (pad);
2750 /* set the caps on the pad to NULL */
2752 clear_caps (GstPad * pad, GValue * ret, gboolean * active)
2754 gst_pad_set_caps (pad, NULL);
2755 gst_object_unref (pad);
2759 /* returns false on error or early cutout (will never happen because the fold
2760 * function always returns TRUE, see FIXME above) of the fold, true if all
2761 * pads in @iter were (de)activated successfully. */
2763 iterator_activate_fold_with_resync (GstIterator * iter,
2764 GstIteratorFoldFunction func, gpointer user_data)
2766 GstIteratorResult ires;
2769 /* no need to unset this later, it's just a boolean */
2770 g_value_init (&ret, G_TYPE_BOOLEAN);
2771 g_value_set_boolean (&ret, TRUE);
2774 ires = gst_iterator_fold (iter, func, &ret, user_data);
2776 case GST_ITERATOR_RESYNC:
2777 /* need to reset the result again */
2778 g_value_set_boolean (&ret, TRUE);
2779 gst_iterator_resync (iter);
2781 case GST_ITERATOR_DONE:
2782 /* all pads iterated, return collected value */
2785 /* iterator returned _ERROR or premature end with _OK,
2786 * mark an error and exit */
2787 g_value_set_boolean (&ret, FALSE);
2792 /* return collected value */
2793 return g_value_get_boolean (&ret);
2796 /* is called with STATE_LOCK
2798 * Pads are activated from source pads to sinkpads.
2801 gst_element_pads_activate (GstElement * element, gboolean active)
2806 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2807 "pads_activate with active %d", active);
2809 iter = gst_element_iterate_src_pads (element);
2811 iterator_activate_fold_with_resync (iter,
2812 (GstIteratorFoldFunction) activate_pads, &active);
2813 gst_iterator_free (iter);
2814 if (G_UNLIKELY (!res))
2817 iter = gst_element_iterate_sink_pads (element);
2819 iterator_activate_fold_with_resync (iter,
2820 (GstIteratorFoldFunction) activate_pads, &active);
2821 gst_iterator_free (iter);
2822 if (G_UNLIKELY (!res))
2826 /* clear the caps on all pads, this should never fail */
2827 iter = gst_element_iterate_pads (element);
2829 iterator_activate_fold_with_resync (iter,
2830 (GstIteratorFoldFunction) clear_caps, &active);
2831 gst_iterator_free (iter);
2832 if (G_UNLIKELY (!res))
2836 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2837 "pads_activate successful");
2844 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2845 "source pads_activate failed");
2850 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2851 "sink pads_activate failed");
2856 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2857 "failed to clear caps on pads");
2862 /* is called with STATE_LOCK */
2863 static GstStateChangeReturn
2864 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2866 GstState state, next;
2867 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2870 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2872 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2873 next = GST_STATE_TRANSITION_NEXT (transition);
2875 /* if the element already is in the given state, we just return success */
2876 if (next == GST_STATE_VOID_PENDING || state == next)
2879 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2880 "default handler tries setting state from %s to %s (%04x)",
2881 gst_element_state_get_name (state),
2882 gst_element_state_get_name (next), transition);
2884 switch (transition) {
2885 case GST_STATE_CHANGE_NULL_TO_READY:
2887 case GST_STATE_CHANGE_READY_TO_PAUSED:
2888 if (!gst_element_pads_activate (element, TRUE)) {
2889 result = GST_STATE_CHANGE_FAILURE;
2892 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2894 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2896 case GST_STATE_CHANGE_PAUSED_TO_READY:
2897 case GST_STATE_CHANGE_READY_TO_NULL:
2898 /* deactivate pads in both cases, since they are activated on
2899 ready->paused but the element might not have made it to paused */
2900 if (!gst_element_pads_activate (element, FALSE)) {
2901 result = GST_STATE_CHANGE_FAILURE;
2903 gst_element_set_base_time (element, 0);
2906 /* In null state release the reference to the clock */
2907 GST_OBJECT_LOCK (element);
2908 clock_p = &element->clock;
2909 gst_object_replace ((GstObject **) clock_p, NULL);
2910 GST_OBJECT_UNLOCK (element);
2913 /* this will catch real but unhandled state changes;
2914 * can only be caused by:
2915 * - a new state was added
2916 * - somehow the element was asked to jump across an intermediate state
2918 g_warning ("Unhandled state change from %s to %s",
2919 gst_element_state_get_name (state),
2920 gst_element_state_get_name (next));
2927 GST_OBJECT_LOCK (element);
2928 result = GST_STATE_RETURN (element);
2929 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2930 "element is already in the %s state",
2931 gst_element_state_get_name (state));
2932 GST_OBJECT_UNLOCK (element);
2939 * gst_element_get_factory:
2940 * @element: a #GstElement to request the element factory of.
2942 * Retrieves the factory that was used to create this element.
2944 * Returns: (transfer none): the #GstElementFactory used for creating this
2945 * element. no refcounting is needed.
2948 gst_element_get_factory (GstElement * element)
2950 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2952 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2956 gst_element_dispose (GObject * object)
2958 GstElement *element = GST_ELEMENT_CAST (object);
2962 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2964 if (GST_STATE (element) != GST_STATE_NULL)
2967 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2968 "removing %d pads", g_list_length (element->pads));
2969 /* first we break all our links with the outside */
2970 while (element->pads && element->pads->data) {
2971 /* don't call _remove_pad with NULL */
2972 gst_element_remove_pad (element, GST_PAD_CAST (element->pads->data));
2974 if (G_UNLIKELY (element->pads != NULL)) {
2975 g_critical ("could not remove pads from element %s",
2976 GST_STR_NULL (GST_OBJECT_NAME (object)));
2979 GST_OBJECT_LOCK (element);
2980 clock_p = &element->clock;
2981 bus_p = &element->bus;
2982 gst_object_replace ((GstObject **) clock_p, NULL);
2983 gst_object_replace ((GstObject **) bus_p, NULL);
2984 GST_OBJECT_UNLOCK (element);
2986 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2988 G_OBJECT_CLASS (parent_class)->dispose (object);
2997 is_locked = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
2999 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
3001 "You need to explicitly set elements to the NULL state before\n"
3002 "dropping the final reference, to allow them to clean up.\n"
3003 "This problem may also be caused by a refcounting bug in the\n"
3004 "application or some element.\n",
3005 GST_OBJECT_NAME (element),
3006 gst_element_state_get_name (GST_STATE (element)),
3007 is_locked ? " (locked)" : "");
3013 gst_element_finalize (GObject * object)
3015 GstElement *element = GST_ELEMENT_CAST (object);
3017 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
3019 GST_STATE_LOCK (element);
3020 if (element->state_cond)
3021 g_cond_free (element->state_cond);
3022 element->state_cond = NULL;
3023 GST_STATE_UNLOCK (element);
3024 g_static_rec_mutex_free (element->state_lock);
3025 g_slice_free (GStaticRecMutex, element->state_lock);
3026 element->state_lock = NULL;
3028 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
3030 G_OBJECT_CLASS (parent_class)->finalize (object);
3033 #if !defined(GST_DISABLE_LOADSAVE) && !defined(GST_REMOVE_DEPRECATED)
3035 * gst_element_save_thyself:
3036 * @element: a #GstElement to save.
3037 * @parent: the xml parent node.
3039 * Saves the element as part of the given XML structure.
3041 * Returns: the new #xmlNodePtr.
3044 gst_element_save_thyself (GstObject * object, xmlNodePtr parent)
3047 GstElementClass *oclass;
3048 GParamSpec **specs, *spec;
3051 GValue value = { 0, };
3052 GstElement *element;
3054 g_return_val_if_fail (GST_IS_ELEMENT (object), parent);
3056 element = GST_ELEMENT_CAST (object);
3058 oclass = GST_ELEMENT_GET_CLASS (element);
3060 xmlNewChild (parent, NULL, (xmlChar *) "name",
3061 (xmlChar *) GST_ELEMENT_NAME (element));
3063 if (oclass->elementfactory != NULL) {
3064 GstElementFactory *factory = (GstElementFactory *) oclass->elementfactory;
3066 xmlNewChild (parent, NULL, (xmlChar *) "type",
3067 (xmlChar *) GST_PLUGIN_FEATURE (factory)->name);
3071 specs = g_object_class_list_properties (G_OBJECT_GET_CLASS (object), &nspecs);
3073 for (i = 0; i < nspecs; i++) {
3075 if (spec->flags & G_PARAM_READABLE) {
3079 g_value_init (&value, spec->value_type);
3081 g_object_get_property (G_OBJECT (element), spec->name, &value);
3082 param = xmlNewChild (parent, NULL, (xmlChar *) "param", NULL);
3083 xmlNewChild (param, NULL, (xmlChar *) "name", (xmlChar *) spec->name);
3085 if (G_IS_PARAM_SPEC_STRING (spec))
3086 contents = g_value_dup_string (&value);
3087 else if (G_IS_PARAM_SPEC_ENUM (spec))
3088 contents = g_strdup_printf ("%d", g_value_get_enum (&value));
3089 else if (G_IS_PARAM_SPEC_INT64 (spec))
3090 contents = g_strdup_printf ("%" G_GINT64_FORMAT,
3091 g_value_get_int64 (&value));
3092 else if (GST_VALUE_HOLDS_STRUCTURE (&value)) {
3093 if (g_value_get_boxed (&value) != NULL) {
3094 contents = g_strdup_value_contents (&value);
3096 contents = g_strdup ("NULL");
3099 contents = g_strdup_value_contents (&value);
3101 xmlNewChild (param, NULL, (xmlChar *) "value", (xmlChar *) contents);
3104 g_value_unset (&value);
3110 pads = g_list_last (GST_ELEMENT_PADS (element));
3113 GstPad *pad = GST_PAD_CAST (pads->data);
3115 /* figure out if it's a direct pad or a ghostpad */
3116 if (GST_ELEMENT_CAST (GST_OBJECT_PARENT (pad)) == element) {
3117 xmlNodePtr padtag = xmlNewChild (parent, NULL, (xmlChar *) "pad", NULL);
3119 gst_object_save_thyself (GST_OBJECT_CAST (pad), padtag);
3121 pads = g_list_previous (pads);
3128 gst_element_restore_thyself (GstObject * object, xmlNodePtr self)
3130 xmlNodePtr children;
3131 GstElement *element;
3133 gchar *value = NULL;
3135 element = GST_ELEMENT_CAST (object);
3136 g_return_if_fail (element != NULL);
3139 children = self->xmlChildrenNode;
3141 if (!strcmp ((char *) children->name, "param")) {
3142 xmlNodePtr child = children->xmlChildrenNode;
3145 if (!strcmp ((char *) child->name, "name")) {
3146 name = (gchar *) xmlNodeGetContent (child);
3147 } else if (!strcmp ((char *) child->name, "value")) {
3148 value = (gchar *) xmlNodeGetContent (child);
3150 child = child->next;
3152 /* FIXME: can this just be g_object_set ? */
3153 gst_util_set_object_arg (G_OBJECT (element), name, value);
3154 /* g_object_set (G_OBJECT (element), name, value, NULL); */
3158 children = children->next;
3162 children = self->xmlChildrenNode;
3164 if (!strcmp ((char *) children->name, "pad")) {
3165 gst_pad_load_and_link (children, GST_OBJECT_CAST (element));
3167 children = children->next;
3170 if (GST_OBJECT_CLASS (parent_class)->restore_thyself)
3171 (GST_OBJECT_CLASS (parent_class)->restore_thyself) (object, self);
3173 #endif /* GST_DISABLE_LOADSAVE */
3176 gst_element_set_bus_func (GstElement * element, GstBus * bus)
3180 g_return_if_fail (GST_IS_ELEMENT (element));
3182 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
3184 GST_OBJECT_LOCK (element);
3185 bus_p = &GST_ELEMENT_BUS (element);
3186 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
3187 GST_OBJECT_UNLOCK (element);
3191 * gst_element_set_bus:
3192 * @element: a #GstElement to set the bus of.
3193 * @bus: (transfer none): the #GstBus to set.
3195 * Sets the bus of the element. Increases the refcount on the bus.
3196 * For internal use only, unless you're testing elements.
3201 gst_element_set_bus (GstElement * element, GstBus * bus)
3203 GstElementClass *oclass;
3205 g_return_if_fail (GST_IS_ELEMENT (element));
3207 oclass = GST_ELEMENT_GET_CLASS (element);
3209 if (oclass->set_bus)
3210 oclass->set_bus (element, bus);
3214 * gst_element_get_bus:
3215 * @element: a #GstElement to get the bus of.
3217 * Returns the bus of the element. Note that only a #GstPipeline will provide a
3218 * bus for the application.
3220 * Returns: (transfer full): the element's #GstBus. unref after usage.
3225 gst_element_get_bus (GstElement * element)
3227 GstBus *result = NULL;
3229 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3231 GST_OBJECT_LOCK (element);
3232 if ((result = GST_ELEMENT_BUS (element)))
3233 gst_object_ref (result);
3234 GST_OBJECT_UNLOCK (element);
3236 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,