2 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
3 * 2004 Wim Taymans <wim@fluendo.com>
5 * gstelement.c: The base element, all elements derive from this
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Library General Public
9 * License as published by the Free Software Foundation; either
10 * version 2 of the License, or (at your option) any later version.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Library General Public License for more details.
17 * You should have received a copy of the GNU Library General Public
18 * License along with this library; if not, write to the
19 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 * Boston, MA 02111-1307, USA.
25 * @short_description: Abstract base class for all pipeline elements
26 * @see_also: #GstElementFactory, #GstPad
28 * GstElement is the abstract base class needed to construct an element that
29 * can be used in a GStreamer pipeline. Please refer to the plugin writers
30 * guide for more information on creating #GstElement subclasses.
32 * The name of a #GstElement can be get with gst_element_get_name() and set with
33 * gst_element_set_name(). For speed, GST_ELEMENT_NAME() can be used in the
34 * core when using the appropriate locking. Do not use this in plug-ins or
35 * applications in order to retain ABI compatibility.
37 * All elements have pads (of the type #GstPad). These pads link to pads on
38 * other elements. #GstBuffer flow between these linked pads.
39 * A #GstElement has a #GList of #GstPad structures for all their input (or sink)
40 * and output (or source) pads.
41 * Core and plug-in writers can add and remove pads with gst_element_add_pad()
42 * and gst_element_remove_pad().
44 * A pad of an element can be retrieved by name with gst_element_get_pad().
45 * An iterator of all pads can be retrieved with gst_element_iterate_pads().
47 * Elements can be linked through their pads.
48 * If the link is straightforward, use the gst_element_link()
49 * convenience function to link two elements, or gst_element_link_many()
50 * for more elements in a row.
51 * Use gst_element_link_filtered() to link two elements constrained by
52 * a specified set of #GstCaps.
53 * For finer control, use gst_element_link_pads() and
54 * gst_element_link_pads_filtered() to specify the pads to link on
55 * each element by name.
57 * Each element has a state (see #GstState). You can get and set the state
58 * of an element with gst_element_get_state() and gst_element_set_state().
59 * Setting a state triggers a #GstStateChange. To get a string representation
60 * of a #GstState, use gst_element_state_get_name().
62 * You can get and set a #GstClock on an element using gst_element_get_clock()
63 * and gst_element_set_clock().
64 * Some elements can provide a clock for the pipeline if
65 * gst_element_provides_clock() returns %TRUE. With the
66 * gst_element_provide_clock() method one can retrieve the clock provided by
68 * Not all elements require a clock to operate correctly. If
69 * gst_element_requires_clock() returns %TRUE, a clock should be set on the
70 * element with gst_element_set_clock().
72 * Note that clock slection and distribution is normally handled by the
73 * toplevel #GstPipeline so the clock functions are only to be used in very
74 * specific situations.
76 * Last reviewed on 2009-05-29 (0.10.24)
79 #include "gst_private.h"
82 #include <gobject/gvaluecollector.h>
84 #include "gstelement.h"
85 #include "gstelementmetadata.h"
86 #include "gstenumtypes.h"
88 #include "gstmarshal.h"
94 #include "gst-i18n-lib.h"
96 /* Element signals and args */
112 static void gst_element_class_init (GstElementClass * klass);
113 static void gst_element_init (GstElement * element);
114 static void gst_element_base_class_init (gpointer g_class);
115 static void gst_element_base_class_finalize (gpointer g_class);
117 static void gst_element_dispose (GObject * object);
118 static void gst_element_finalize (GObject * object);
120 static GstStateChangeReturn gst_element_change_state_func (GstElement * element,
121 GstStateChange transition);
122 static GstStateChangeReturn gst_element_get_state_func (GstElement * element,
123 GstState * state, GstState * pending, GstClockTime timeout);
124 static GstStateChangeReturn gst_element_set_state_func (GstElement * element,
126 static void gst_element_set_bus_func (GstElement * element, GstBus * bus);
128 static gboolean gst_element_default_send_event (GstElement * element,
130 static gboolean gst_element_default_query (GstElement * element,
133 static GstPadTemplate
134 * gst_element_class_get_request_pad_template (GstElementClass *
135 element_class, const gchar * name);
137 static GstObjectClass *parent_class = NULL;
138 static guint gst_element_signals[LAST_SIGNAL] = { 0 };
140 /* this is used in gstelementfactory.c:gst_element_register() */
141 GQuark _gst_elementclass_factory = 0;
144 gst_element_get_type (void)
146 static volatile gsize gst_element_type = 0;
148 if (g_once_init_enter (&gst_element_type)) {
150 static const GTypeInfo element_info = {
151 sizeof (GstElementClass),
152 gst_element_base_class_init,
153 gst_element_base_class_finalize,
154 (GClassInitFunc) gst_element_class_init,
159 (GInstanceInitFunc) gst_element_init,
163 _type = g_type_register_static (GST_TYPE_OBJECT, "GstElement",
164 &element_info, G_TYPE_FLAG_ABSTRACT);
166 _gst_elementclass_factory =
167 g_quark_from_static_string ("GST_ELEMENTCLASS_FACTORY");
168 g_once_init_leave (&gst_element_type, _type);
170 return gst_element_type;
174 gst_element_class_init (GstElementClass * klass)
176 GObjectClass *gobject_class;
177 GstObjectClass *gstobject_class;
179 gobject_class = (GObjectClass *) klass;
180 gstobject_class = (GstObjectClass *) klass;
182 parent_class = g_type_class_peek_parent (klass);
185 * GstElement::pad-added:
186 * @gstelement: the object which received the signal
187 * @new_pad: the pad that has been added
189 * a new #GstPad has been added to the element. Note that this signal will
190 * usually be emitted from the context of the streaming thread. Also keep in
191 * mind that if you add new elements to the pipeline in the signal handler
192 * you will need to set them to the desired target state with
193 * gst_element_set() or gst_element_sync_state_with_parent().
195 gst_element_signals[PAD_ADDED] =
196 g_signal_new ("pad-added", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
197 G_STRUCT_OFFSET (GstElementClass, pad_added), NULL, NULL,
198 gst_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GST_TYPE_PAD);
200 * GstElement::pad-removed:
201 * @gstelement: the object which received the signal
202 * @old_pad: the pad that has been removed
204 * a #GstPad has been removed from the element
206 gst_element_signals[PAD_REMOVED] =
207 g_signal_new ("pad-removed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
208 G_STRUCT_OFFSET (GstElementClass, pad_removed), NULL, NULL,
209 gst_marshal_VOID__OBJECT, G_TYPE_NONE, 1, GST_TYPE_PAD);
211 * GstElement::no-more-pads:
212 * @gstelement: the object which received the signal
214 * This signals that the element will not generate more dynamic pads.
215 * Note that this signal will usually be emitted from the context of
216 * the streaming thread.
218 gst_element_signals[NO_MORE_PADS] =
219 g_signal_new ("no-more-pads", G_TYPE_FROM_CLASS (klass),
220 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstElementClass, no_more_pads), NULL,
221 NULL, gst_marshal_VOID__VOID, G_TYPE_NONE, 0);
223 gobject_class->dispose = gst_element_dispose;
224 gobject_class->finalize = gst_element_finalize;
226 klass->change_state = GST_DEBUG_FUNCPTR (gst_element_change_state_func);
227 klass->set_state = GST_DEBUG_FUNCPTR (gst_element_set_state_func);
228 klass->get_state = GST_DEBUG_FUNCPTR (gst_element_get_state_func);
229 klass->set_bus = GST_DEBUG_FUNCPTR (gst_element_set_bus_func);
230 klass->query = GST_DEBUG_FUNCPTR (gst_element_default_query);
231 klass->send_event = GST_DEBUG_FUNCPTR (gst_element_default_send_event);
232 klass->numpadtemplates = 0;
234 klass->elementfactory = NULL;
238 gst_element_base_class_init (gpointer g_class)
240 GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
242 /* FIXME 0.11: Instead of clearing the
243 * pad template list copy the list and increase the refcount of
244 * the pad templates by one.
246 * This will make it possible to add pad templates and set element
247 * details in the class_init functions and is the real GObject way
249 * See http://bugzilla.gnome.org/show_bug.cgi?id=491501
251 element_class->metadata = gst_structure_empty_new ("metadata");
252 element_class->padtemplates = NULL;
254 /* set the factory, see gst_element_register() */
255 element_class->elementfactory =
256 g_type_get_qdata (G_TYPE_FROM_CLASS (element_class),
257 _gst_elementclass_factory);
258 GST_DEBUG ("type %s : factory %p", G_OBJECT_CLASS_NAME (element_class),
259 element_class->elementfactory);
263 gst_element_base_class_finalize (gpointer g_class)
265 GstElementClass *klass = GST_ELEMENT_CLASS (g_class);
267 g_list_foreach (klass->padtemplates, (GFunc) gst_object_unref, NULL);
268 g_list_free (klass->padtemplates);
270 gst_structure_free (klass->metadata);
274 gst_element_init (GstElement * element)
276 GST_STATE (element) = GST_STATE_NULL;
277 GST_STATE_TARGET (element) = GST_STATE_NULL;
278 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
279 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
280 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
282 /* FIXME 0.11: Store this directly in the instance struct */
283 element->state_lock = g_slice_new (GStaticRecMutex);
284 g_static_rec_mutex_init (element->state_lock);
285 element->state_cond = g_cond_new ();
289 * gst_element_release_request_pad:
290 * @element: a #GstElement to release the request pad of.
291 * @pad: the #GstPad to release.
293 * Makes the element free the previously requested pad as obtained
294 * with gst_element_get_request_pad().
296 * This does not unref the pad. If the pad was created by using
297 * gst_element_get_request_pad(), gst_element_release_request_pad() needs to be
298 * followed by gst_object_unref() to free the @pad.
303 gst_element_release_request_pad (GstElement * element, GstPad * pad)
305 GstElementClass *oclass;
307 g_return_if_fail (GST_IS_ELEMENT (element));
308 g_return_if_fail (GST_IS_PAD (pad));
310 oclass = GST_ELEMENT_GET_CLASS (element);
312 /* if the element implements a custom release function we call that, else we
313 * simply remove the pad from the element */
314 if (oclass->release_pad)
315 (oclass->release_pad) (element, pad);
317 gst_element_remove_pad (element, pad);
321 * gst_element_requires_clock:
322 * @element: a #GstElement to query
324 * Query if the element requires a clock.
326 * Returns: %TRUE if the element requires a clock
331 gst_element_requires_clock (GstElement * element)
335 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
337 result = (GST_ELEMENT_GET_CLASS (element)->set_clock != NULL);
343 * gst_element_provides_clock:
344 * @element: a #GstElement to query
346 * Query if the element provides a clock. A #GstClock provided by an
347 * element can be used as the global #GstClock for the pipeline.
348 * An element that can provide a clock is only required to do so in the PAUSED
349 * state, this means when it is fully negotiated and has allocated the resources
350 * to operate the clock.
352 * Returns: %TRUE if the element provides a clock
357 gst_element_provides_clock (GstElement * element)
361 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
363 result = (GST_ELEMENT_GET_CLASS (element)->provide_clock != NULL);
369 * gst_element_provide_clock:
370 * @element: a #GstElement to query
372 * Get the clock provided by the given element.
373 * <note>An element is only required to provide a clock in the PAUSED
374 * state. Some elements can provide a clock in other states.</note>
376 * Returns: (transfer full): the GstClock provided by the element or %NULL
377 * if no clock could be provided. Unref after usage.
382 gst_element_provide_clock (GstElement * element)
384 GstClock *result = NULL;
385 GstElementClass *oclass;
387 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
389 oclass = GST_ELEMENT_GET_CLASS (element);
391 if (oclass->provide_clock)
392 result = oclass->provide_clock (element);
398 * gst_element_set_clock:
399 * @element: a #GstElement to set the clock for.
400 * @clock: the #GstClock to set for the element.
402 * Sets the clock for the element. This function increases the
403 * refcount on the clock. Any previously set clock on the object
406 * Returns: %TRUE if the element accepted the clock. An element can refuse a
407 * clock when it, for example, is not able to slave its internal clock to the
408 * @clock or when it requires a specific clock to operate.
413 gst_element_set_clock (GstElement * element, GstClock * clock)
415 GstElementClass *oclass;
419 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
420 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
422 oclass = GST_ELEMENT_GET_CLASS (element);
424 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
426 if (oclass->set_clock)
427 res = oclass->set_clock (element, clock);
430 /* only update the clock pointer if the element accepted the clock */
431 GST_OBJECT_LOCK (element);
432 clock_p = &element->clock;
433 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
434 GST_OBJECT_UNLOCK (element);
440 * gst_element_get_clock:
441 * @element: a #GstElement to get the clock of.
443 * Gets the currently configured clock of the element. This is the clock as was
444 * last set with gst_element_set_clock().
446 * Returns: (transfer full): the #GstClock of the element. unref after usage.
451 gst_element_get_clock (GstElement * element)
455 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
457 GST_OBJECT_LOCK (element);
458 if ((result = element->clock))
459 gst_object_ref (result);
460 GST_OBJECT_UNLOCK (element);
466 * gst_element_set_base_time:
467 * @element: a #GstElement.
468 * @time: the base time to set.
470 * Set the base time of an element. See gst_element_get_base_time().
475 gst_element_set_base_time (GstElement * element, GstClockTime time)
479 g_return_if_fail (GST_IS_ELEMENT (element));
481 GST_OBJECT_LOCK (element);
482 old = element->base_time;
483 element->base_time = time;
484 GST_OBJECT_UNLOCK (element);
486 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
487 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
488 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
492 * gst_element_get_base_time:
493 * @element: a #GstElement.
495 * Returns the base time of the element. The base time is the
496 * absolute time of the clock when this element was last put to
497 * PLAYING. Subtracting the base time from the clock time gives
498 * the running time of the element.
500 * Returns: the base time of the element.
505 gst_element_get_base_time (GstElement * element)
509 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
511 GST_OBJECT_LOCK (element);
512 result = element->base_time;
513 GST_OBJECT_UNLOCK (element);
519 * gst_element_set_start_time:
520 * @element: a #GstElement.
521 * @time: the base time to set.
523 * Set the start time of an element. The start time of the element is the
524 * running time of the element when it last went to the PAUSED state. In READY
525 * or after a flushing seek, it is set to 0.
527 * Toplevel elements like #GstPipeline will manage the start_time and
528 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
529 * on such a toplevel element will disable the distribution of the base_time to
530 * the children and can be useful if the application manages the base_time
531 * itself, for example if you want to synchronize capture from multiple
532 * pipelines, and you can also ensure that the pipelines have the same clock.
539 gst_element_set_start_time (GstElement * element, GstClockTime time)
543 g_return_if_fail (GST_IS_ELEMENT (element));
545 GST_OBJECT_LOCK (element);
546 old = GST_ELEMENT_START_TIME (element);
547 GST_ELEMENT_START_TIME (element) = time;
548 GST_OBJECT_UNLOCK (element);
550 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
551 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
552 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
556 * gst_element_get_start_time:
557 * @element: a #GstElement.
559 * Returns the start time of the element. The start time is the
560 * running time of the clock when this element was last put to PAUSED.
562 * Usually the start_time is managed by a toplevel element such as
567 * Returns: the start time of the element.
572 gst_element_get_start_time (GstElement * element)
576 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
578 GST_OBJECT_LOCK (element);
579 result = GST_ELEMENT_START_TIME (element);
580 GST_OBJECT_UNLOCK (element);
586 * gst_element_is_indexable:
587 * @element: a #GstElement.
589 * Queries if the element can be indexed.
591 * Returns: TRUE if the element can be indexed.
596 gst_element_is_indexable (GstElement * element)
600 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
602 result = (GST_ELEMENT_GET_CLASS (element)->set_index != NULL);
608 * gst_element_set_index:
609 * @element: a #GstElement.
610 * @index: (transfer none): a #GstIndex.
612 * Set @index on the element. The refcount of the index
613 * will be increased, any previously set index is unreffed.
618 gst_element_set_index (GstElement * element, GstIndex * index)
620 GstElementClass *oclass;
622 g_return_if_fail (GST_IS_ELEMENT (element));
623 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
625 oclass = GST_ELEMENT_GET_CLASS (element);
627 if (oclass->set_index)
628 oclass->set_index (element, index);
632 * gst_element_get_index:
633 * @element: a #GstElement.
635 * Gets the index from the element.
637 * Returns: (transfer full): a #GstIndex or %NULL when no index was set on the
638 * element. unref after usage.
643 gst_element_get_index (GstElement * element)
645 GstElementClass *oclass;
646 GstIndex *result = NULL;
648 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
650 oclass = GST_ELEMENT_GET_CLASS (element);
652 if (oclass->get_index)
653 result = oclass->get_index (element);
659 * gst_element_add_pad:
660 * @element: a #GstElement to add the pad to.
661 * @pad: (transfer full): the #GstPad to add to the element.
663 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
664 * see gst_object_set_parent() for refcounting information.
666 * Pads are not automatically activated so elements should perform the needed
667 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
668 * state. See gst_pad_set_active() for more information about activating pads.
670 * The pad and the element should be unlocked when calling this function.
672 * This function will emit the #GstElement::pad-added signal on the element.
674 * Returns: %TRUE if the pad could be added. This function can fail when
675 * a pad with the same name already existed or the pad already had another
681 gst_element_add_pad (GstElement * element, GstPad * pad)
686 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
687 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
689 /* locking pad to look at the name */
690 GST_OBJECT_LOCK (pad);
691 pad_name = g_strdup (GST_PAD_NAME (pad));
692 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
693 GST_STR_NULL (pad_name));
694 flushing = GST_PAD_IS_FLUSHING (pad);
695 GST_OBJECT_UNLOCK (pad);
697 /* then check to see if there's already a pad by that name here */
698 GST_OBJECT_LOCK (element);
699 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
702 /* try to set the pad's parent */
703 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
704 GST_OBJECT_CAST (element))))
707 /* check for flushing pads */
708 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
709 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
710 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
711 "use gst_pad_set_active(pad,TRUE) before adding it.",
712 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
714 GST_OBJECT_LOCK (pad);
715 GST_PAD_UNSET_FLUSHING (pad);
716 GST_OBJECT_UNLOCK (pad);
721 /* add it to the list */
722 switch (gst_pad_get_direction (pad)) {
724 element->srcpads = g_list_prepend (element->srcpads, pad);
725 element->numsrcpads++;
728 element->sinkpads = g_list_prepend (element->sinkpads, pad);
729 element->numsinkpads++;
734 element->pads = g_list_prepend (element->pads, pad);
736 element->pads_cookie++;
737 GST_OBJECT_UNLOCK (element);
739 /* emit the PAD_ADDED signal */
740 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
747 g_critical ("Padname %s is not unique in element %s, not adding",
748 pad_name, GST_ELEMENT_NAME (element));
749 GST_OBJECT_UNLOCK (element);
756 ("Pad %s already has parent when trying to add to element %s",
757 pad_name, GST_ELEMENT_NAME (element));
758 GST_OBJECT_UNLOCK (element);
764 GST_OBJECT_LOCK (pad);
766 ("Trying to add pad %s to element %s, but it has no direction",
767 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
768 GST_OBJECT_UNLOCK (pad);
769 GST_OBJECT_UNLOCK (element);
775 * gst_element_remove_pad:
776 * @element: a #GstElement to remove pad from.
777 * @pad: (transfer none): the #GstPad to remove from the element.
779 * Removes @pad from @element. @pad will be destroyed if it has not been
780 * referenced elsewhere using gst_object_unparent().
782 * This function is used by plugin developers and should not be used
783 * by applications. Pads that were dynamically requested from elements
784 * with gst_element_get_request_pad() should be released with the
785 * gst_element_release_request_pad() function instead.
787 * Pads are not automatically deactivated so elements should perform the needed
788 * steps to deactivate the pad in case this pad is removed in the PAUSED or
789 * PLAYING state. See gst_pad_set_active() for more information about
792 * The pad and the element should be unlocked when calling this function.
794 * This function will emit the #GstElement::pad-removed signal on the element.
796 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
797 * pad does not belong to the provided element.
802 gst_element_remove_pad (GstElement * element, GstPad * pad)
806 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
807 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
809 /* locking pad to look at the name and parent */
810 GST_OBJECT_LOCK (pad);
811 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
812 GST_STR_NULL (GST_PAD_NAME (pad)));
814 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
816 GST_OBJECT_UNLOCK (pad);
819 if ((peer = gst_pad_get_peer (pad))) {
820 /* window for MT unsafeness, someone else could unlink here
821 * and then we call unlink with wrong pads. The unlink
822 * function would catch this and safely return failed. */
823 if (GST_PAD_IS_SRC (pad))
824 gst_pad_unlink (pad, peer);
826 gst_pad_unlink (peer, pad);
828 gst_object_unref (peer);
831 GST_OBJECT_LOCK (element);
832 /* remove it from the list */
833 switch (gst_pad_get_direction (pad)) {
835 element->srcpads = g_list_remove (element->srcpads, pad);
836 element->numsrcpads--;
839 element->sinkpads = g_list_remove (element->sinkpads, pad);
840 element->numsinkpads--;
843 g_critical ("Removing pad without direction???");
846 element->pads = g_list_remove (element->pads, pad);
848 element->pads_cookie++;
849 GST_OBJECT_UNLOCK (element);
851 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
852 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
854 gst_object_unparent (GST_OBJECT_CAST (pad));
861 /* FIXME, locking order? */
862 GST_OBJECT_LOCK (element);
863 g_critical ("Padname %s:%s does not belong to element %s when removing",
864 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
865 GST_OBJECT_UNLOCK (element);
866 GST_OBJECT_UNLOCK (pad);
872 * gst_element_no_more_pads:
873 * @element: a #GstElement
875 * Use this function to signal that the element does not expect any more pads
876 * to show up in the current pipeline. This function should be called whenever
877 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
878 * pad templates use this in combination with autopluggers to figure out that
879 * the element is done initializing its pads.
881 * This function emits the #GstElement::no-more-pads signal.
886 gst_element_no_more_pads (GstElement * element)
888 g_return_if_fail (GST_IS_ELEMENT (element));
890 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
894 pad_compare_name (GstPad * pad1, const gchar * name)
898 GST_OBJECT_LOCK (pad1);
899 result = strcmp (GST_PAD_NAME (pad1), name);
900 GST_OBJECT_UNLOCK (pad1);
906 * gst_element_get_static_pad:
907 * @element: a #GstElement to find a static pad of.
908 * @name: the name of the static #GstPad to retrieve.
910 * Retrieves a pad from @element by name. This version only retrieves
911 * already-existing (i.e. 'static') pads.
913 * Returns: (transfer full): the requested #GstPad if found, otherwise %NULL.
919 gst_element_get_static_pad (GstElement * element, const gchar * name)
922 GstPad *result = NULL;
924 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
925 g_return_val_if_fail (name != NULL, NULL);
927 GST_OBJECT_LOCK (element);
929 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
931 result = GST_PAD_CAST (find->data);
932 gst_object_ref (result);
935 if (result == NULL) {
936 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
937 name, GST_ELEMENT_NAME (element));
939 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
940 GST_ELEMENT_NAME (element), name);
942 GST_OBJECT_UNLOCK (element);
948 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
949 const gchar * name, const GstCaps * caps)
951 GstPad *newpad = NULL;
952 GstElementClass *oclass;
954 oclass = GST_ELEMENT_GET_CLASS (element);
956 #ifndef G_DISABLE_CHECKS
957 /* Some sanity checking here */
961 /* Is this the template name? */
962 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
963 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
965 const gchar *str, *data;
968 /* Otherwise check if it's a valid name for the name template */
969 str = strchr (templ->name_template, '%');
970 g_return_val_if_fail (str != NULL, NULL);
971 g_return_val_if_fail (strncmp (templ->name_template, name,
972 str - templ->name_template) == 0, NULL);
973 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
975 data = name + (str - templ->name_template);
977 /* Can either be %s or %d or %u, do sanity checking for %d */
978 if (*(str + 1) == 'd') {
982 tmp = g_ascii_strtoll (data, &endptr, 10);
983 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
984 && *endptr == '\0', NULL);
985 } else if (*(str + 1) == 'u') {
989 tmp = g_ascii_strtoull (data, &endptr, 10);
990 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
994 pad = gst_element_get_static_pad (element, name);
996 gst_object_unref (pad);
997 /* FIXME 0.11: Change this to g_return_val_if_fail() */
998 g_critical ("Element %s already has a pad named %s, the behaviour of "
999 " gst_element_get_request_pad() for existing pads is undefined!",
1000 GST_ELEMENT_NAME (element), name);
1005 if (oclass->request_new_pad_full)
1006 newpad = (oclass->request_new_pad_full) (element, templ, name, caps);
1007 else if (oclass->request_new_pad)
1008 newpad = (oclass->request_new_pad) (element, templ, name);
1011 gst_object_ref (newpad);
1017 * gst_element_get_request_pad:
1018 * @element: a #GstElement to find a request pad of.
1019 * @name: the name of the request #GstPad to retrieve.
1021 * Retrieves a pad from the element by name. This version only retrieves
1022 * request pads. The pad should be released with
1023 * gst_element_release_request_pad().
1025 * This method is slow and will be deprecated in the future. New code should
1026 * use gst_element_request_pad() with the requested template.
1028 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1029 * Release after usage.
1032 gst_element_get_request_pad (GstElement * element, const gchar * name)
1034 GstPadTemplate *templ = NULL;
1036 const gchar *req_name = NULL;
1037 gboolean templ_found = FALSE;
1040 gchar *str, *endptr = NULL;
1041 GstElementClass *class;
1043 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1044 g_return_val_if_fail (name != NULL, NULL);
1046 class = GST_ELEMENT_GET_CLASS (element);
1048 /* if the name contains a %, we assume it's the complete template name. Get
1049 * the template and try to get a pad */
1050 if (strstr (name, "%")) {
1051 templ = gst_element_class_get_request_pad_template (class, name);
1056 /* there is no % in the name, try to find a matching template */
1057 list = class->padtemplates;
1058 while (!templ_found && list) {
1059 templ = (GstPadTemplate *) list->data;
1060 if (templ->presence == GST_PAD_REQUEST) {
1061 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1062 templ->name_template);
1063 /* see if we find an exact match */
1064 if (strcmp (name, templ->name_template) == 0) {
1069 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1070 and %d and %u, occurring at the end of the name_template, are the only
1072 else if ((str = strchr (templ->name_template, '%'))
1073 && strncmp (templ->name_template, name,
1074 str - templ->name_template) == 0
1075 && strlen (name) > str - templ->name_template) {
1076 data = name + (str - templ->name_template);
1077 if (*(str + 1) == 'd') {
1081 tmp = strtol (data, &endptr, 10);
1082 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1088 } else if (*(str + 1) == 'u') {
1092 tmp = strtoul (data, &endptr, 10);
1093 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1113 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1119 * gst_element_request_pad:
1120 * @element: a #GstElement to find a request pad of.
1121 * @templ: a #GstPadTemplate of which we want a pad of.
1122 * @name: (transfer none) (allow-none): the name of the request #GstPad
1123 * to retrieve. Can be %NULL.
1124 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1125 * request. Can be %NULL.
1127 * Retrieves a request pad from the element according to the provided template.
1129 * If the @caps are specified and the element implements thew new
1130 * request_new_pad_full virtual method, the element will use them to select
1131 * which pad to create.
1133 * The pad should be released with gst_element_release_request_pad().
1135 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1136 * Release after usage.
1141 gst_element_request_pad (GstElement * element,
1142 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1144 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1145 g_return_val_if_fail (templ != NULL, NULL);
1147 return _gst_element_request_pad (element, templ, name, caps);
1151 * gst_element_get_pad:
1152 * @element: a #GstElement.
1153 * @name: the name of the pad to retrieve.
1155 * Retrieves a pad from @element by name. Tries gst_element_get_static_pad()
1156 * first, then gst_element_get_request_pad().
1158 * Deprecated: This function is deprecated as it's unclear if the reference
1159 * to the result pad should be released with gst_object_unref() in case of a static pad
1160 * or gst_element_release_request_pad() in case of a request pad.
1161 * Use gst_element_get_static_pad() or gst_element_get_request_pad() instead.
1163 * Returns: (transfer full): the #GstPad if found, otherwise %NULL. Unref or Release after usage,
1164 * depending on the type of the pad.
1166 #ifndef GST_REMOVE_DEPRECATED
1167 #ifdef GST_DISABLE_DEPRECATED
1168 GstPad *gst_element_get_pad (GstElement * element, const gchar * name);
1171 gst_element_get_pad (GstElement * element, const gchar * name)
1175 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1176 g_return_val_if_fail (name != NULL, NULL);
1178 pad = gst_element_get_static_pad (element, name);
1180 pad = gst_element_get_request_pad (element, name);
1184 #endif /* GST_REMOVE_DEPRECATED */
1186 static GstIteratorItem
1187 iterate_pad (GstIterator * it, GstPad * pad)
1189 gst_object_ref (pad);
1190 return GST_ITERATOR_ITEM_PASS;
1193 static GstIterator *
1194 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1196 GstIterator *result;
1198 GST_OBJECT_LOCK (element);
1199 gst_object_ref (element);
1200 result = gst_iterator_new_list (GST_TYPE_PAD,
1201 GST_OBJECT_GET_LOCK (element),
1202 &element->pads_cookie,
1205 (GstIteratorItemFunction) iterate_pad,
1206 (GstIteratorDisposeFunction) gst_object_unref);
1207 GST_OBJECT_UNLOCK (element);
1213 * gst_element_iterate_pads:
1214 * @element: a #GstElement to iterate pads of.
1216 * Retrieves an iterattor of @element's pads. The iterator should
1217 * be freed after usage.
1219 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1225 gst_element_iterate_pads (GstElement * element)
1227 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1229 return gst_element_iterate_pad_list (element, &element->pads);
1233 * gst_element_iterate_src_pads:
1234 * @element: a #GstElement.
1236 * Retrieves an iterator of @element's source pads.
1238 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1244 gst_element_iterate_src_pads (GstElement * element)
1246 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1248 return gst_element_iterate_pad_list (element, &element->srcpads);
1252 * gst_element_iterate_sink_pads:
1253 * @element: a #GstElement.
1255 * Retrieves an iterator of @element's sink pads.
1257 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1263 gst_element_iterate_sink_pads (GstElement * element)
1265 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1267 return gst_element_iterate_pad_list (element, &element->sinkpads);
1271 * gst_element_class_add_pad_template:
1272 * @klass: the #GstElementClass to add the pad template to.
1273 * @templ: (transfer none): a #GstPadTemplate to add to the element class.
1275 * Adds a padtemplate to an element class. This is mainly used in the _base_init
1276 * functions of classes.
1279 gst_element_class_add_pad_template (GstElementClass * klass,
1280 GstPadTemplate * templ)
1282 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1283 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1285 /* FIXME 0.11: allow replacing the pad templates by
1286 * calling this with the same name as an already existing pad
1287 * template. For this we _must_ _not_ ref the added pad template
1288 * a second time and _must_ document that this function takes
1289 * ownership of the pad template. Otherwise we will leak pad templates
1290 * or the caller unref's the pad template and it disappears */
1291 /* avoid registering pad templates with the same name */
1292 g_return_if_fail (gst_element_class_get_pad_template (klass,
1293 templ->name_template) == NULL);
1295 klass->padtemplates = g_list_append (klass->padtemplates,
1296 gst_object_ref (templ));
1297 klass->numpadtemplates++;
1301 * gst_element_class_add_metadata:
1302 * @klass: class to set metadata for
1303 * @key: the key to set
1304 * @value: the value to set
1306 * Set @key with @value as metadata in @klass.
1309 gst_element_class_add_metadata (GstElementClass * klass,
1310 const gchar * key, const gchar * value)
1312 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1313 g_return_if_fail (key != NULL);
1314 g_return_if_fail (value != NULL);
1316 gst_structure_set ((GstStructure *) klass->metadata,
1317 key, G_TYPE_STRING, value, NULL);
1321 * gst_element_class_set_metadata:
1322 * @klass: class to set metadata for
1323 * @longname: The long English name of the element. E.g. "File Sink"
1324 * @classification: String describing the type of element, as an unordered list
1325 * separated with slashes ('/'). See draft-klass.txt of the design docs
1326 * for more details and common types. E.g: "Sink/File"
1327 * @description: Sentence describing the purpose of the element.
1328 * E.g: "Write stream to a file"
1329 * @author: Name and contact details of the author(s). Use \n to separate
1330 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1332 * Sets the detailed information for a #GstElementClass.
1333 * <note>This function is for use in _base_init functions only.</note>
1336 gst_element_class_set_metadata (GstElementClass * klass,
1337 const gchar * longname, const gchar * classification,
1338 const gchar * description, const gchar * author)
1340 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1342 gst_structure_set ((GstStructure *) klass->metadata,
1343 GST_ELEMENT_METADATA_LONGNAME, G_TYPE_STRING, longname,
1344 GST_ELEMENT_METADATA_KLASS, G_TYPE_STRING, classification,
1345 GST_ELEMENT_METADATA_DESCRIPTION, G_TYPE_STRING, description,
1346 GST_ELEMENT_METADATA_AUTHOR, G_TYPE_STRING, author, NULL);
1350 * gst_element_class_get_pad_template_list:
1351 * @element_class: a #GstElementClass to get pad templates of.
1353 * Retrieves a list of the pad templates associated with @element_class. The
1354 * list must not be modified by the calling code.
1355 * <note>If you use this function in the #GInstanceInitFunc of an object class
1356 * that has subclasses, make sure to pass the g_class parameter of the
1357 * #GInstanceInitFunc here.</note>
1359 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1363 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1365 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1367 return element_class->padtemplates;
1371 * gst_element_class_get_pad_template:
1372 * @element_class: a #GstElementClass to get the pad template of.
1373 * @name: the name of the #GstPadTemplate to get.
1375 * Retrieves a padtemplate from @element_class with the given name.
1376 * <note>If you use this function in the #GInstanceInitFunc of an object class
1377 * that has subclasses, make sure to pass the g_class parameter of the
1378 * #GInstanceInitFunc here.</note>
1380 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1381 * if none was found. No unreferencing is necessary.
1384 gst_element_class_get_pad_template (GstElementClass *
1385 element_class, const gchar * name)
1389 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1390 g_return_val_if_fail (name != NULL, NULL);
1392 padlist = element_class->padtemplates;
1395 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1397 if (strcmp (padtempl->name_template, name) == 0)
1400 padlist = g_list_next (padlist);
1406 static GstPadTemplate *
1407 gst_element_class_get_request_pad_template (GstElementClass *
1408 element_class, const gchar * name)
1410 GstPadTemplate *tmpl;
1412 tmpl = gst_element_class_get_pad_template (element_class, name);
1413 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1419 /* get a random pad on element of the given direction.
1420 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1423 gst_element_get_random_pad (GstElement * element,
1424 gboolean need_linked, GstPadDirection dir)
1426 GstPad *result = NULL;
1429 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1433 GST_OBJECT_LOCK (element);
1434 pads = element->srcpads;
1437 GST_OBJECT_LOCK (element);
1438 pads = element->sinkpads;
1441 goto wrong_direction;
1443 for (; pads; pads = g_list_next (pads)) {
1444 GstPad *pad = GST_PAD_CAST (pads->data);
1446 GST_OBJECT_LOCK (pad);
1447 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1448 GST_DEBUG_PAD_NAME (pad));
1450 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1451 /* if we require a linked pad, and it is not linked, continue the
1453 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1454 GST_DEBUG_PAD_NAME (pad));
1455 GST_OBJECT_UNLOCK (pad);
1458 /* found a pad, stop search */
1459 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1460 GST_DEBUG_PAD_NAME (pad));
1461 GST_OBJECT_UNLOCK (pad);
1467 gst_object_ref (result);
1469 GST_OBJECT_UNLOCK (element);
1473 /* ERROR handling */
1476 g_warning ("unknown pad direction %d", dir);
1482 gst_element_default_send_event (GstElement * element, GstEvent * event)
1484 gboolean result = FALSE;
1487 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1488 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1489 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1492 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1493 "pushing %s event to random %s pad %s:%s",
1494 GST_EVENT_TYPE_NAME (event),
1495 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1496 GST_DEBUG_PAD_NAME (pad));
1498 result = gst_pad_push_event (pad, event);
1499 gst_object_unref (pad);
1501 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1502 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1508 * gst_element_send_event:
1509 * @element: a #GstElement to send the event to.
1510 * @event: (transfer full): the #GstEvent to send to the element.
1512 * Sends an event to an element. If the element doesn't implement an
1513 * event handler, the event will be pushed on a random linked sink pad for
1514 * upstream events or a random linked source pad for downstream events.
1516 * This function takes owership of the provided event so you should
1517 * gst_event_ref() it if you want to reuse the event after this call.
1519 * Returns: %TRUE if the event was handled.
1524 gst_element_send_event (GstElement * element, GstEvent * event)
1526 GstElementClass *oclass;
1527 gboolean result = FALSE;
1529 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1530 g_return_val_if_fail (event != NULL, FALSE);
1532 oclass = GST_ELEMENT_GET_CLASS (element);
1534 GST_STATE_LOCK (element);
1535 if (oclass->send_event) {
1536 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1537 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1538 result = oclass->send_event (element, event);
1540 result = gst_element_default_send_event (element, event);
1542 GST_STATE_UNLOCK (element);
1549 * @element: a #GstElement to send the event to.
1550 * @rate: The new playback rate
1551 * @format: The format of the seek values
1552 * @flags: The optional seek flags.
1553 * @cur_type: The type and flags for the new current position
1554 * @cur: The value of the new current position
1555 * @stop_type: The type and flags for the new stop position
1556 * @stop: The value of the new stop position
1558 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1559 * the parameters. The seek event is sent to the element using
1560 * gst_element_send_event().
1562 * Returns: %TRUE if the event was handled.
1567 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1568 GstSeekFlags flags, GstSeekType cur_type, gint64 cur,
1569 GstSeekType stop_type, gint64 stop)
1574 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1577 gst_event_new_seek (rate, format, flags, cur_type, cur, stop_type, stop);
1578 result = gst_element_send_event (element, event);
1584 * gst_element_get_query_types:
1585 * @element: a #GstElement to query
1587 * Get an array of query types from the element.
1588 * If the element doesn't implement a query types function,
1589 * the query will be forwarded to the peer of a random linked sink pad.
1591 * Returns: An array of #GstQueryType elements that should not
1592 * be freed or modified.
1596 const GstQueryType *
1597 gst_element_get_query_types (GstElement * element)
1599 GstElementClass *oclass;
1600 const GstQueryType *result = NULL;
1602 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1604 oclass = GST_ELEMENT_GET_CLASS (element);
1606 if (oclass->get_query_types) {
1607 result = oclass->get_query_types (element);
1609 GstPad *pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1612 GstPad *peer = gst_pad_get_peer (pad);
1615 result = gst_pad_get_query_types (peer);
1617 gst_object_unref (peer);
1619 gst_object_unref (pad);
1626 gst_element_default_query (GstElement * element, GstQuery * query)
1628 gboolean result = FALSE;
1631 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1633 result = gst_pad_query (pad, query);
1635 gst_object_unref (pad);
1637 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1639 GstPad *peer = gst_pad_get_peer (pad);
1642 result = gst_pad_query (peer, query);
1644 gst_object_unref (peer);
1646 gst_object_unref (pad);
1653 * gst_element_query:
1654 * @element: a #GstElement to perform the query on.
1655 * @query: (transfer none): the #GstQuery.
1657 * Performs a query on the given element.
1659 * For elements that don't implement a query handler, this function
1660 * forwards the query to a random srcpad or to the peer of a
1661 * random linked sinkpad of this element.
1663 * Please note that some queries might need a running pipeline to work.
1665 * Returns: TRUE if the query could be performed.
1670 gst_element_query (GstElement * element, GstQuery * query)
1672 GstElementClass *oclass;
1673 gboolean result = FALSE;
1675 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1676 g_return_val_if_fail (query != NULL, FALSE);
1678 oclass = GST_ELEMENT_GET_CLASS (element);
1680 if (oclass->query) {
1681 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1682 GST_ELEMENT_NAME (element));
1683 result = oclass->query (element, query);
1685 result = gst_element_default_query (element, query);
1691 * gst_element_post_message:
1692 * @element: a #GstElement posting the message
1693 * @message: (transfer full): a #GstMessage to post
1695 * Post a message on the element's #GstBus. This function takes ownership of the
1696 * message; if you want to access the message after this call, you should add an
1697 * additional reference before calling.
1699 * Returns: %TRUE if the message was successfully posted. The function returns
1700 * %FALSE if the element did not have a bus.
1705 gst_element_post_message (GstElement * element, GstMessage * message)
1708 gboolean result = FALSE;
1710 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1711 g_return_val_if_fail (message != NULL, FALSE);
1713 GST_OBJECT_LOCK (element);
1716 if (G_UNLIKELY (bus == NULL))
1719 gst_object_ref (bus);
1720 GST_OBJECT_UNLOCK (element);
1722 /* we release the element lock when posting the message so that any
1723 * (synchronous) message handlers can operate on the element */
1724 result = gst_bus_post (bus, message);
1725 gst_object_unref (bus);
1732 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1733 "not posting message %p: no bus", message);
1734 GST_OBJECT_UNLOCK (element);
1735 gst_message_unref (message);
1741 * _gst_element_error_printf:
1742 * @format: the printf-like format to use, or %NULL
1744 * This function is only used internally by the gst_element_error() macro.
1746 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1752 _gst_element_error_printf (const gchar * format, ...)
1762 va_start (args, format);
1763 buffer = g_strdup_vprintf (format, args);
1769 * gst_element_message_full:
1770 * @element: a #GstElement to send message from
1771 * @type: the #GstMessageType
1772 * @domain: the GStreamer GError domain this message belongs to
1773 * @code: the GError code belonging to the domain
1774 * @text: (allow-none) (transfer full): an allocated text string to be used
1775 * as a replacement for the default message connected to code,
1777 * @debug: (allow-none) (transfer full): an allocated debug message to be
1778 * used as a replacement for the default debugging information,
1780 * @file: the source code file where the error was generated
1781 * @function: the source code function where the error was generated
1782 * @line: the source code line where the error was generated
1784 * Post an error, warning or info message on the bus from inside an element.
1786 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1787 * #GST_MESSAGE_INFO.
1791 void gst_element_message_full
1792 (GstElement * element, GstMessageType type,
1793 GQuark domain, gint code, gchar * text,
1794 gchar * debug, const gchar * file, const gchar * function, gint line)
1796 GError *gerror = NULL;
1800 gboolean has_debug = TRUE;
1801 GstMessage *message = NULL;
1804 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1805 g_return_if_fail (GST_IS_ELEMENT (element));
1806 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1807 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1809 /* check if we send the given text or the default error text */
1810 if ((text == NULL) || (text[0] == 0)) {
1811 /* text could have come from g_strdup_printf (""); */
1813 sent_text = gst_error_get_message (domain, code);
1817 /* construct a sent_debug with extra information from source */
1818 if ((debug == NULL) || (debug[0] == 0)) {
1819 /* debug could have come from g_strdup_printf (""); */
1823 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1825 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1826 file, line, function, name, debug);
1828 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1829 file, line, function, name);
1833 /* create gerror and post message */
1834 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1836 gerror = g_error_new_literal (domain, code, sent_text);
1839 case GST_MESSAGE_ERROR:
1841 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1843 case GST_MESSAGE_WARNING:
1844 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1847 case GST_MESSAGE_INFO:
1848 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1852 g_assert_not_reached ();
1855 gst_element_post_message (element, message);
1857 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1858 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1861 g_error_free (gerror);
1862 g_free (sent_debug);
1867 * gst_element_is_locked_state:
1868 * @element: a #GstElement.
1870 * Checks if the state of an element is locked.
1871 * If the state of an element is locked, state changes of the parent don't
1872 * affect the element.
1873 * This way you can leave currently unused elements inside bins. Just lock their
1874 * state before changing the state from #GST_STATE_NULL.
1878 * Returns: TRUE, if the element's state is locked.
1881 gst_element_is_locked_state (GstElement * element)
1885 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1887 GST_OBJECT_LOCK (element);
1888 result = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1889 GST_OBJECT_UNLOCK (element);
1895 * gst_element_set_locked_state:
1896 * @element: a #GstElement
1897 * @locked_state: TRUE to lock the element's state
1899 * Locks the state of an element, so state changes of the parent don't affect
1900 * this element anymore.
1904 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1905 * or the elements state-locking needed no change.
1908 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1912 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1914 GST_OBJECT_LOCK (element);
1915 old = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
1917 if (G_UNLIKELY (old == locked_state))
1921 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1922 GST_ELEMENT_NAME (element));
1923 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_LOCKED_STATE);
1925 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1926 GST_ELEMENT_NAME (element));
1927 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_LOCKED_STATE);
1929 GST_OBJECT_UNLOCK (element);
1935 GST_CAT_DEBUG (GST_CAT_STATES,
1936 "elements %s was already in locked state %d",
1937 GST_ELEMENT_NAME (element), old);
1938 GST_OBJECT_UNLOCK (element);
1945 * gst_element_sync_state_with_parent:
1946 * @element: a #GstElement.
1948 * Tries to change the state of the element to the same as its parent.
1949 * If this function returns FALSE, the state of element is undefined.
1951 * Returns: TRUE, if the element's state could be synced to the parent's state.
1956 gst_element_sync_state_with_parent (GstElement * element)
1960 GstStateChangeReturn ret;
1962 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1964 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1965 GstState parent_current, parent_pending;
1967 GST_OBJECT_LOCK (parent);
1968 parent_current = GST_STATE (parent);
1969 parent_pending = GST_STATE_PENDING (parent);
1970 GST_OBJECT_UNLOCK (parent);
1972 /* set to pending if there is one, else we set it to the current state of
1974 if (parent_pending != GST_STATE_VOID_PENDING)
1975 target = parent_pending;
1977 target = parent_current;
1979 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1980 "syncing state (%s) to parent %s %s (%s, %s)",
1981 gst_element_state_get_name (GST_STATE (element)),
1982 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1983 gst_element_state_get_name (parent_current),
1984 gst_element_state_get_name (parent_pending));
1986 ret = gst_element_set_state (element, target);
1987 if (ret == GST_STATE_CHANGE_FAILURE)
1990 gst_object_unref (parent);
1994 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
2001 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2002 "syncing state failed (%s)",
2003 gst_element_state_change_return_get_name (ret));
2004 gst_object_unref (parent);
2010 static GstStateChangeReturn
2011 gst_element_get_state_func (GstElement * element,
2012 GstState * state, GstState * pending, GstClockTime timeout)
2014 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2015 GstState old_pending;
2017 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2018 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2020 GST_OBJECT_LOCK (element);
2021 ret = GST_STATE_RETURN (element);
2022 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2023 gst_element_state_change_return_get_name (ret));
2025 /* we got an error, report immediately */
2026 if (ret == GST_STATE_CHANGE_FAILURE)
2029 /* we got no_preroll, report immediatly */
2030 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2033 /* no need to wait async if we are not async */
2034 if (ret != GST_STATE_CHANGE_ASYNC)
2037 old_pending = GST_STATE_PENDING (element);
2038 if (old_pending != GST_STATE_VOID_PENDING) {
2039 GTimeVal *timeval, abstimeout;
2042 if (timeout != GST_CLOCK_TIME_NONE) {
2043 glong add = timeout / 1000;
2048 /* make timeout absolute */
2049 g_get_current_time (&abstimeout);
2050 g_time_val_add (&abstimeout, add);
2051 timeval = &abstimeout;
2055 /* get cookie to detect state changes during waiting */
2056 cookie = element->state_cookie;
2058 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2059 "waiting for element to commit state");
2061 /* we have a pending state change, wait for it to complete */
2062 if (!GST_STATE_TIMED_WAIT (element, timeval)) {
2063 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2064 /* timeout triggered */
2065 ret = GST_STATE_CHANGE_ASYNC;
2067 if (cookie != element->state_cookie)
2070 /* could be success or failure */
2071 if (old_pending == GST_STATE (element)) {
2072 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2073 ret = GST_STATE_CHANGE_SUCCESS;
2075 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2076 ret = GST_STATE_CHANGE_FAILURE;
2079 /* if nothing is pending anymore we can return SUCCESS */
2080 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2081 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2082 ret = GST_STATE_CHANGE_SUCCESS;
2088 *state = GST_STATE (element);
2090 *pending = GST_STATE_PENDING (element);
2092 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2093 "state current: %s, pending: %s, result: %s",
2094 gst_element_state_get_name (GST_STATE (element)),
2095 gst_element_state_get_name (GST_STATE_PENDING (element)),
2096 gst_element_state_change_return_get_name (ret));
2097 GST_OBJECT_UNLOCK (element);
2104 *state = GST_STATE_VOID_PENDING;
2106 *pending = GST_STATE_VOID_PENDING;
2108 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2110 GST_OBJECT_UNLOCK (element);
2112 return GST_STATE_CHANGE_FAILURE;
2117 * gst_element_get_state:
2118 * @element: a #GstElement to get the state of.
2119 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2121 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2122 * state. Can be %NULL.
2123 * @timeout: a #GstClockTime to specify the timeout for an async
2124 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2126 * Gets the state of the element.
2128 * For elements that performed an ASYNC state change, as reported by
2129 * gst_element_set_state(), this function will block up to the
2130 * specified timeout value for the state change to complete.
2131 * If the element completes the state change or goes into
2132 * an error, this function returns immediately with a return value of
2133 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2135 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2136 * returns the current and pending state immediately.
2138 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2139 * successfully changed its state but is not able to provide data yet.
2140 * This mostly happens for live sources that only produce data in
2141 * %GST_STATE_PLAYING. While the state change return is equivalent to
2142 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2143 * some sink elements might not be able to complete their state change because
2144 * an element is not producing data to complete the preroll. When setting the
2145 * element to playing, the preroll will complete and playback will start.
2147 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2148 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2149 * element is still performing a state change or
2150 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2154 GstStateChangeReturn
2155 gst_element_get_state (GstElement * element,
2156 GstState * state, GstState * pending, GstClockTime timeout)
2158 GstElementClass *oclass;
2159 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2161 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2163 oclass = GST_ELEMENT_GET_CLASS (element);
2165 if (oclass->get_state)
2166 result = (oclass->get_state) (element, state, pending, timeout);
2172 * gst_element_abort_state:
2173 * @element: a #GstElement to abort the state of.
2175 * Abort the state change of the element. This function is used
2176 * by elements that do asynchronous state changes and find out
2177 * something is wrong.
2179 * This function should be called with the STATE_LOCK held.
2184 gst_element_abort_state (GstElement * element)
2188 #ifndef GST_DISABLE_GST_DEBUG
2192 g_return_if_fail (GST_IS_ELEMENT (element));
2194 GST_OBJECT_LOCK (element);
2195 pending = GST_STATE_PENDING (element);
2197 if (pending == GST_STATE_VOID_PENDING ||
2198 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2199 goto nothing_aborted;
2201 #ifndef GST_DISABLE_GST_DEBUG
2202 old_state = GST_STATE (element);
2204 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2205 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2206 gst_element_state_get_name (pending));
2210 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2212 GST_STATE_BROADCAST (element);
2213 GST_OBJECT_UNLOCK (element);
2219 GST_OBJECT_UNLOCK (element);
2225 * gst_element_continue_state:
2226 * @element: a #GstElement to continue the state change of.
2227 * @ret: The previous state return value
2229 * Commit the state change of the element and proceed to the next
2230 * pending state if any. This function is used
2231 * by elements that do asynchronous state changes.
2232 * The core will normally call this method automatically when an
2233 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2235 * If after calling this method the element still has not reached
2236 * the pending state, the next state change is performed.
2238 * This method is used internally and should normally not be called by plugins
2241 * Returns: The result of the commit state change.
2245 GstStateChangeReturn
2246 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2248 GstStateChangeReturn old_ret;
2249 GstState old_state, old_next;
2250 GstState current, next, pending;
2251 GstMessage *message;
2252 GstStateChange transition;
2254 GST_OBJECT_LOCK (element);
2255 old_ret = GST_STATE_RETURN (element);
2256 GST_STATE_RETURN (element) = ret;
2257 pending = GST_STATE_PENDING (element);
2259 /* check if there is something to commit */
2260 if (pending == GST_STATE_VOID_PENDING)
2261 goto nothing_pending;
2263 old_state = GST_STATE (element);
2264 /* this is the state we should go to next */
2265 old_next = GST_STATE_NEXT (element);
2266 /* update current state */
2267 current = GST_STATE (element) = old_next;
2269 /* see if we reached the final state */
2270 if (pending == current)
2273 next = GST_STATE_GET_NEXT (current, pending);
2274 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2276 GST_STATE_NEXT (element) = next;
2278 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2279 GST_OBJECT_UNLOCK (element);
2281 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2282 "committing state from %s to %s, pending %s, next %s",
2283 gst_element_state_get_name (old_state),
2284 gst_element_state_get_name (old_next),
2285 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2287 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2288 old_state, old_next, pending);
2289 gst_element_post_message (element, message);
2291 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2292 "continue state change %s to %s, final %s",
2293 gst_element_state_get_name (current),
2294 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2296 ret = gst_element_change_state (element, transition);
2302 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2303 GST_OBJECT_UNLOCK (element);
2308 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2309 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2311 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2312 "completed state change to %s", gst_element_state_get_name (pending));
2313 GST_OBJECT_UNLOCK (element);
2315 /* don't post silly messages with the same state. This can happen
2316 * when an element state is changed to what it already was. For bins
2317 * this can be the result of a lost state, which we check with the
2318 * previous return value.
2319 * We do signal the cond though as a _get_state() might be blocking
2321 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC) {
2322 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2323 "posting state-changed %s to %s",
2324 gst_element_state_get_name (old_state),
2325 gst_element_state_get_name (old_next));
2327 gst_message_new_state_changed (GST_OBJECT_CAST (element), old_state,
2328 old_next, GST_STATE_VOID_PENDING);
2329 gst_element_post_message (element, message);
2332 GST_STATE_BROADCAST (element);
2339 * gst_element_lost_state_full:
2340 * @element: a #GstElement the state is lost of
2341 * @new_base_time: if a new base time should be distributed
2343 * Brings the element to the lost state. The current state of the
2344 * element is copied to the pending state so that any call to
2345 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2347 * An ASYNC_START message is posted with indication to distribute a new
2348 * base_time to the element when @new_base_time is %TRUE.
2349 * If the element was PLAYING, it will go to PAUSED. The element
2350 * will be restored to its PLAYING state by the parent pipeline when it
2353 * This is mostly used for elements that lost their preroll buffer
2354 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2355 * they will go to their pending state again when a new preroll buffer is
2356 * queued. This function can only be called when the element is currently
2357 * not in error or an async state change.
2359 * This function is used internally and should normally not be called from
2360 * plugins or applications.
2367 gst_element_lost_state_full (GstElement * element, gboolean new_base_time)
2369 GstState old_state, new_state;
2370 GstMessage *message;
2372 g_return_if_fail (GST_IS_ELEMENT (element));
2374 GST_OBJECT_LOCK (element);
2375 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2378 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2379 goto only_async_start;
2381 old_state = GST_STATE (element);
2383 /* when we were PLAYING, the new state is PAUSED. We will also not
2384 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2385 * when we preroll. */
2386 if (old_state > GST_STATE_PAUSED)
2387 new_state = GST_STATE_PAUSED;
2389 new_state = old_state;
2391 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2392 "lost state of %s to %s", gst_element_state_get_name (old_state),
2393 gst_element_state_get_name (new_state));
2395 GST_STATE (element) = new_state;
2396 GST_STATE_NEXT (element) = new_state;
2397 GST_STATE_PENDING (element) = new_state;
2398 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2400 GST_ELEMENT_START_TIME (element) = 0;
2401 GST_OBJECT_UNLOCK (element);
2403 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2404 new_state, new_state, new_state);
2405 gst_element_post_message (element, message);
2408 gst_message_new_async_start (GST_OBJECT_CAST (element), new_base_time);
2409 gst_element_post_message (element, message);
2415 GST_OBJECT_UNLOCK (element);
2420 GST_OBJECT_UNLOCK (element);
2422 message = gst_message_new_async_start (GST_OBJECT_CAST (element), TRUE);
2423 gst_element_post_message (element, message);
2429 * gst_element_lost_state:
2430 * @element: a #GstElement the state is lost of
2432 * Brings the element to the lost state. This function calls
2433 * gst_element_lost_state_full() with the new_base_time set to %TRUE.
2435 * This function is used internally and should normally not be called from
2436 * plugins or applications.
2441 gst_element_lost_state (GstElement * element)
2443 gst_element_lost_state_full (element, TRUE);
2447 * gst_element_set_state:
2448 * @element: a #GstElement to change state of.
2449 * @state: the element's new #GstState.
2451 * Sets the state of the element. This function will try to set the
2452 * requested state by going through all the intermediary states and calling
2453 * the class's state change function for each.
2455 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2456 * element will perform the remainder of the state change asynchronously in
2458 * An application can use gst_element_get_state() to wait for the completion
2459 * of the state change or it can wait for a state change message on the bus.
2461 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2462 * #GST_STATE_CHANGE_ASYNC.
2464 * Returns: Result of the state change using #GstStateChangeReturn.
2468 GstStateChangeReturn
2469 gst_element_set_state (GstElement * element, GstState state)
2471 GstElementClass *oclass;
2472 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2474 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2476 oclass = GST_ELEMENT_GET_CLASS (element);
2478 if (oclass->set_state)
2479 result = (oclass->set_state) (element, state);
2485 * default set state function, calculates the next state based
2486 * on current state and calls the change_state function
2488 static GstStateChangeReturn
2489 gst_element_set_state_func (GstElement * element, GstState state)
2491 GstState current, next, old_pending;
2492 GstStateChangeReturn ret;
2493 GstStateChange transition;
2494 GstStateChangeReturn old_ret;
2496 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2498 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2499 gst_element_state_get_name (state));
2501 /* state lock is taken to protect the set_state() and get_state()
2502 * procedures, it does not lock any variables. */
2503 GST_STATE_LOCK (element);
2505 /* now calculate how to get to the new state */
2506 GST_OBJECT_LOCK (element);
2507 old_ret = GST_STATE_RETURN (element);
2508 /* previous state change returned an error, remove all pending
2509 * and next states */
2510 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2511 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2512 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2513 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2516 current = GST_STATE (element);
2517 next = GST_STATE_NEXT (element);
2518 old_pending = GST_STATE_PENDING (element);
2520 /* this is the (new) state we should go to. TARGET is the last state we set on
2522 if (state != GST_STATE_TARGET (element)) {
2523 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2524 "setting target state to %s", gst_element_state_get_name (state));
2525 GST_STATE_TARGET (element) = state;
2526 /* increment state cookie so that we can track each state change. We only do
2527 * this if this is actually a new state change. */
2528 element->state_cookie++;
2530 GST_STATE_PENDING (element) = state;
2532 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2533 "current %s, old_pending %s, next %s, old return %s",
2534 gst_element_state_get_name (current),
2535 gst_element_state_get_name (old_pending),
2536 gst_element_state_get_name (next),
2537 gst_element_state_change_return_get_name (old_ret));
2539 /* if the element was busy doing a state change, we just update the
2540 * target state, it'll get to it async then. */
2541 if (old_pending != GST_STATE_VOID_PENDING) {
2542 /* upwards state change will happen ASYNC */
2543 if (old_pending <= state)
2545 /* element is going to this state already */
2546 else if (next == state)
2548 /* element was performing an ASYNC upward state change and
2549 * we request to go downward again. Start from the next pending
2551 else if (next > state
2552 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2556 next = GST_STATE_GET_NEXT (current, state);
2557 /* now we store the next state */
2558 GST_STATE_NEXT (element) = next;
2559 /* mark busy, we need to check that there is actually a state change
2560 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2561 * the default element change_state function has no way to know what the
2562 * old value was... could consider this a FIXME...*/
2563 if (current != next)
2564 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2566 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2568 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2569 "%s: setting state from %s to %s",
2570 (next != state ? "intermediate" : "final"),
2571 gst_element_state_get_name (current), gst_element_state_get_name (next));
2573 /* now signal any waiters, they will error since the cookie was incremented */
2574 GST_STATE_BROADCAST (element);
2576 GST_OBJECT_UNLOCK (element);
2578 ret = gst_element_change_state (element, transition);
2580 GST_STATE_UNLOCK (element);
2582 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2583 gst_element_state_change_return_get_name (ret));
2589 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2590 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2591 "element was busy with async state change");
2592 GST_OBJECT_UNLOCK (element);
2594 GST_STATE_UNLOCK (element);
2596 return GST_STATE_CHANGE_ASYNC;
2601 * gst_element_change_state:
2602 * @element: a #GstElement
2603 * @transition: the requested transition
2605 * Perform @transition on @element.
2607 * This function must be called with STATE_LOCK held and is mainly used
2610 * Returns: the #GstStateChangeReturn of the state transition.
2612 GstStateChangeReturn
2613 gst_element_change_state (GstElement * element, GstStateChange transition)
2615 GstElementClass *oclass;
2616 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2618 oclass = GST_ELEMENT_GET_CLASS (element);
2620 /* call the state change function so it can set the state */
2621 if (oclass->change_state)
2622 ret = (oclass->change_state) (element, transition);
2624 ret = GST_STATE_CHANGE_FAILURE;
2627 case GST_STATE_CHANGE_FAILURE:
2628 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2629 "have FAILURE change_state return");
2630 /* state change failure */
2631 gst_element_abort_state (element);
2633 case GST_STATE_CHANGE_ASYNC:
2637 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2638 "element will change state ASYNC");
2640 target = GST_STATE_TARGET (element);
2642 if (target > GST_STATE_READY)
2645 /* else we just continue the state change downwards */
2646 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2647 "forcing commit state %s <= %s",
2648 gst_element_state_get_name (target),
2649 gst_element_state_get_name (GST_STATE_READY));
2651 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2654 case GST_STATE_CHANGE_SUCCESS:
2655 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2656 "element changed state SUCCESS");
2657 /* we can commit the state now which will proceeed to
2659 ret = gst_element_continue_state (element, ret);
2661 case GST_STATE_CHANGE_NO_PREROLL:
2662 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2663 "element changed state NO_PREROLL");
2664 /* we can commit the state now which will proceeed to
2666 ret = gst_element_continue_state (element, ret);
2669 goto invalid_return;
2672 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2677 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2685 GST_OBJECT_LOCK (element);
2686 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2687 g_critical ("%s: unknown return value %d from a state change function",
2688 GST_ELEMENT_NAME (element), ret);
2690 /* we are in error now */
2691 ret = GST_STATE_CHANGE_FAILURE;
2692 GST_STATE_RETURN (element) = ret;
2693 GST_OBJECT_UNLOCK (element);
2699 /* gst_iterator_fold functions for pads_activate
2700 * Note how we don't stop the iterator when we fail an activation. This is
2701 * probably a FIXME since when one pad activation fails, we don't want to
2702 * continue our state change. */
2704 activate_pads (GstPad * pad, GValue * ret, gboolean * active)
2706 if (!gst_pad_set_active (pad, *active))
2707 g_value_set_boolean (ret, FALSE);
2709 /* unref the object that was reffed for us by _fold */
2710 gst_object_unref (pad);
2714 /* set the caps on the pad to NULL */
2716 clear_caps (GstPad * pad, GValue * ret, gboolean * active)
2718 gst_pad_set_caps (pad, NULL);
2719 gst_object_unref (pad);
2723 /* returns false on error or early cutout (will never happen because the fold
2724 * function always returns TRUE, see FIXME above) of the fold, true if all
2725 * pads in @iter were (de)activated successfully. */
2727 iterator_activate_fold_with_resync (GstIterator * iter,
2728 GstIteratorFoldFunction func, gpointer user_data)
2730 GstIteratorResult ires;
2733 /* no need to unset this later, it's just a boolean */
2734 g_value_init (&ret, G_TYPE_BOOLEAN);
2735 g_value_set_boolean (&ret, TRUE);
2738 ires = gst_iterator_fold (iter, func, &ret, user_data);
2740 case GST_ITERATOR_RESYNC:
2741 /* need to reset the result again */
2742 g_value_set_boolean (&ret, TRUE);
2743 gst_iterator_resync (iter);
2745 case GST_ITERATOR_DONE:
2746 /* all pads iterated, return collected value */
2749 /* iterator returned _ERROR or premature end with _OK,
2750 * mark an error and exit */
2751 g_value_set_boolean (&ret, FALSE);
2756 /* return collected value */
2757 return g_value_get_boolean (&ret);
2760 /* is called with STATE_LOCK
2762 * Pads are activated from source pads to sinkpads.
2765 gst_element_pads_activate (GstElement * element, gboolean active)
2770 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2771 "pads_activate with active %d", active);
2773 iter = gst_element_iterate_src_pads (element);
2775 iterator_activate_fold_with_resync (iter,
2776 (GstIteratorFoldFunction) activate_pads, &active);
2777 gst_iterator_free (iter);
2778 if (G_UNLIKELY (!res))
2781 iter = gst_element_iterate_sink_pads (element);
2783 iterator_activate_fold_with_resync (iter,
2784 (GstIteratorFoldFunction) activate_pads, &active);
2785 gst_iterator_free (iter);
2786 if (G_UNLIKELY (!res))
2790 /* clear the caps on all pads, this should never fail */
2791 iter = gst_element_iterate_pads (element);
2793 iterator_activate_fold_with_resync (iter,
2794 (GstIteratorFoldFunction) clear_caps, &active);
2795 gst_iterator_free (iter);
2796 if (G_UNLIKELY (!res))
2800 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2801 "pads_activate successful");
2808 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2809 "source pads_activate failed");
2814 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2815 "sink pads_activate failed");
2820 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2821 "failed to clear caps on pads");
2826 /* is called with STATE_LOCK */
2827 static GstStateChangeReturn
2828 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2830 GstState state, next;
2831 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2834 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2836 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2837 next = GST_STATE_TRANSITION_NEXT (transition);
2839 /* if the element already is in the given state, we just return success */
2840 if (next == GST_STATE_VOID_PENDING || state == next)
2843 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2844 "default handler tries setting state from %s to %s (%04x)",
2845 gst_element_state_get_name (state),
2846 gst_element_state_get_name (next), transition);
2848 switch (transition) {
2849 case GST_STATE_CHANGE_NULL_TO_READY:
2851 case GST_STATE_CHANGE_READY_TO_PAUSED:
2852 if (!gst_element_pads_activate (element, TRUE)) {
2853 result = GST_STATE_CHANGE_FAILURE;
2856 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2858 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2860 case GST_STATE_CHANGE_PAUSED_TO_READY:
2861 case GST_STATE_CHANGE_READY_TO_NULL:
2862 /* deactivate pads in both cases, since they are activated on
2863 ready->paused but the element might not have made it to paused */
2864 if (!gst_element_pads_activate (element, FALSE)) {
2865 result = GST_STATE_CHANGE_FAILURE;
2867 gst_element_set_base_time (element, 0);
2870 /* In null state release the reference to the clock */
2871 GST_OBJECT_LOCK (element);
2872 clock_p = &element->clock;
2873 gst_object_replace ((GstObject **) clock_p, NULL);
2874 GST_OBJECT_UNLOCK (element);
2877 /* this will catch real but unhandled state changes;
2878 * can only be caused by:
2879 * - a new state was added
2880 * - somehow the element was asked to jump across an intermediate state
2882 g_warning ("Unhandled state change from %s to %s",
2883 gst_element_state_get_name (state),
2884 gst_element_state_get_name (next));
2891 GST_OBJECT_LOCK (element);
2892 result = GST_STATE_RETURN (element);
2893 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2894 "element is already in the %s state",
2895 gst_element_state_get_name (state));
2896 GST_OBJECT_UNLOCK (element);
2903 * gst_element_get_factory:
2904 * @element: a #GstElement to request the element factory of.
2906 * Retrieves the factory that was used to create this element.
2908 * Returns: (transfer none): the #GstElementFactory used for creating this
2909 * element. no refcounting is needed.
2912 gst_element_get_factory (GstElement * element)
2914 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2916 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2920 gst_element_dispose (GObject * object)
2922 GstElement *element = GST_ELEMENT_CAST (object);
2926 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2928 if (GST_STATE (element) != GST_STATE_NULL)
2931 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2932 "removing %d pads", g_list_length (element->pads));
2933 /* first we break all our links with the outside */
2934 while (element->pads && element->pads->data) {
2935 /* don't call _remove_pad with NULL */
2936 gst_element_remove_pad (element, GST_PAD_CAST (element->pads->data));
2938 if (G_UNLIKELY (element->pads != NULL)) {
2939 g_critical ("could not remove pads from element %s",
2940 GST_STR_NULL (GST_OBJECT_NAME (object)));
2943 GST_OBJECT_LOCK (element);
2944 clock_p = &element->clock;
2945 bus_p = &element->bus;
2946 gst_object_replace ((GstObject **) clock_p, NULL);
2947 gst_object_replace ((GstObject **) bus_p, NULL);
2948 GST_OBJECT_UNLOCK (element);
2950 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2952 G_OBJECT_CLASS (parent_class)->dispose (object);
2961 is_locked = GST_OBJECT_FLAG_IS_SET (element, GST_ELEMENT_LOCKED_STATE);
2963 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2965 "You need to explicitly set elements to the NULL state before\n"
2966 "dropping the final reference, to allow them to clean up.\n"
2967 "This problem may also be caused by a refcounting bug in the\n"
2968 "application or some element.\n",
2969 GST_OBJECT_NAME (element),
2970 gst_element_state_get_name (GST_STATE (element)),
2971 is_locked ? " (locked)" : "");
2977 gst_element_finalize (GObject * object)
2979 GstElement *element = GST_ELEMENT_CAST (object);
2981 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2983 GST_STATE_LOCK (element);
2984 if (element->state_cond)
2985 g_cond_free (element->state_cond);
2986 element->state_cond = NULL;
2987 GST_STATE_UNLOCK (element);
2988 g_static_rec_mutex_free (element->state_lock);
2989 g_slice_free (GStaticRecMutex, element->state_lock);
2990 element->state_lock = NULL;
2992 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2994 G_OBJECT_CLASS (parent_class)->finalize (object);
2998 gst_element_set_bus_func (GstElement * element, GstBus * bus)
3002 g_return_if_fail (GST_IS_ELEMENT (element));
3004 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
3006 GST_OBJECT_LOCK (element);
3007 bus_p = &GST_ELEMENT_BUS (element);
3008 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
3009 GST_OBJECT_UNLOCK (element);
3013 * gst_element_set_bus:
3014 * @element: a #GstElement to set the bus of.
3015 * @bus: (transfer none): the #GstBus to set.
3017 * Sets the bus of the element. Increases the refcount on the bus.
3018 * For internal use only, unless you're testing elements.
3023 gst_element_set_bus (GstElement * element, GstBus * bus)
3025 GstElementClass *oclass;
3027 g_return_if_fail (GST_IS_ELEMENT (element));
3029 oclass = GST_ELEMENT_GET_CLASS (element);
3031 if (oclass->set_bus)
3032 oclass->set_bus (element, bus);
3036 * gst_element_get_bus:
3037 * @element: a #GstElement to get the bus of.
3039 * Returns the bus of the element. Note that only a #GstPipeline will provide a
3040 * bus for the application.
3042 * Returns: (transfer full): the element's #GstBus. unref after usage.
3047 gst_element_get_bus (GstElement * element)
3049 GstBus *result = NULL;
3051 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3053 GST_OBJECT_LOCK (element);
3054 if ((result = GST_ELEMENT_BUS (element)))
3055 gst_object_ref (result);
3056 GST_OBJECT_UNLOCK (element);
3058 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,