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., 51 Franklin St, Fifth Floor,
20 * Boston, MA 02110-1301, 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 * Elements can have pads (of the type #GstPad). These pads link to pads on
38 * other elements. #GstBuffer flow between these linked pads.
39 * A #GstElement has a #GList of #GstPad structures for all their input (or sink)
40 * and output (or source) pads.
41 * Core and plug-in writers can add and remove pads with gst_element_add_pad()
42 * and gst_element_remove_pad().
44 * An existing pad of an element can be retrieved by name with
45 * gst_element_get_static_pad(). A new dynamic pad can be created using
46 * gst_element_request_pad() with a #GstPadTemplate.
47 * An iterator of all pads can be retrieved with gst_element_iterate_pads().
49 * Elements can be linked through their pads.
50 * If the link is straightforward, use the gst_element_link()
51 * convenience function to link two elements, or gst_element_link_many()
52 * for more elements in a row.
53 * Use gst_element_link_filtered() to link two elements constrained by
54 * a specified set of #GstCaps.
55 * For finer control, use gst_element_link_pads() and
56 * gst_element_link_pads_filtered() to specify the pads to link on
57 * each element by name.
59 * Each element has a state (see #GstState). You can get and set the state
60 * of an element with gst_element_get_state() and gst_element_set_state().
61 * Setting a state triggers a #GstStateChange. To get a string representation
62 * of a #GstState, use gst_element_state_get_name().
64 * You can get and set a #GstClock on an element using gst_element_get_clock()
65 * and gst_element_set_clock().
66 * Some elements can provide a clock for the pipeline if
67 * the #GST_ELEMENT_FLAG_PROVIDE_CLOCK flag is set. With the
68 * gst_element_provide_clock() method one can retrieve the clock provided by
70 * Not all elements require a clock to operate correctly. If the
71 * #GST_ELEMENT_FLAG_REQUIRE_CLOCK() flag is set, a clock should be set on the
72 * element with gst_element_set_clock().
74 * Note that clock selection and distribution is normally handled by the
75 * toplevel #GstPipeline so the clock functions are only to be used in very
76 * specific situations.
79 #include "gst_private.h"
82 #include <gobject/gvaluecollector.h>
84 #include "gstelement.h"
85 #include "gstelementmetadata.h"
86 #include "gstenumtypes.h"
94 #include "gst-i18n-lib.h"
95 #include "glib-compat-private.h"
97 #ifndef GST_DISABLE_GST_DEBUG
98 #include "printf/printf.h"
101 /* Element signals and args */
117 static void gst_element_class_init (GstElementClass * klass);
118 static void gst_element_init (GstElement * element);
119 static void gst_element_base_class_init (gpointer g_class);
120 static void gst_element_base_class_finalize (gpointer g_class);
122 static void gst_element_dispose (GObject * object);
123 static void gst_element_finalize (GObject * object);
125 static GstStateChangeReturn gst_element_change_state_func (GstElement * element,
126 GstStateChange transition);
127 static GstStateChangeReturn gst_element_get_state_func (GstElement * element,
128 GstState * state, GstState * pending, GstClockTime timeout);
129 static GstStateChangeReturn gst_element_set_state_func (GstElement * element,
131 static gboolean gst_element_set_clock_func (GstElement * element,
133 static void gst_element_set_bus_func (GstElement * element, GstBus * bus);
134 static gboolean gst_element_post_message_default (GstElement * element,
135 GstMessage * message);
137 static gboolean gst_element_default_send_event (GstElement * element,
139 static gboolean gst_element_default_query (GstElement * element,
142 static GstPadTemplate
143 * gst_element_class_get_request_pad_template (GstElementClass *
144 element_class, const gchar * name);
146 static GstObjectClass *parent_class = NULL;
147 static guint gst_element_signals[LAST_SIGNAL] = { 0 };
149 /* this is used in gstelementfactory.c:gst_element_register() */
150 GQuark __gst_elementclass_factory = 0;
153 gst_element_get_type (void)
155 static volatile gsize gst_element_type = 0;
157 if (g_once_init_enter (&gst_element_type)) {
159 static const GTypeInfo element_info = {
160 sizeof (GstElementClass),
161 gst_element_base_class_init,
162 gst_element_base_class_finalize,
163 (GClassInitFunc) gst_element_class_init,
168 (GInstanceInitFunc) gst_element_init,
172 _type = g_type_register_static (GST_TYPE_OBJECT, "GstElement",
173 &element_info, G_TYPE_FLAG_ABSTRACT);
175 __gst_elementclass_factory =
176 g_quark_from_static_string ("GST_ELEMENTCLASS_FACTORY");
177 g_once_init_leave (&gst_element_type, _type);
179 return gst_element_type;
183 gst_element_class_init (GstElementClass * klass)
185 GObjectClass *gobject_class;
187 gobject_class = (GObjectClass *) klass;
189 parent_class = g_type_class_peek_parent (klass);
192 * GstElement::pad-added:
193 * @gstelement: the object which received the signal
194 * @new_pad: the pad that has been added
196 * a new #GstPad has been added to the element. Note that this signal will
197 * usually be emitted from the context of the streaming thread. Also keep in
198 * mind that if you add new elements to the pipeline in the signal handler
199 * you will need to set them to the desired target state with
200 * gst_element_set_state() or gst_element_sync_state_with_parent().
202 gst_element_signals[PAD_ADDED] =
203 g_signal_new ("pad-added", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
204 G_STRUCT_OFFSET (GstElementClass, pad_added), NULL, NULL,
205 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
207 * GstElement::pad-removed:
208 * @gstelement: the object which received the signal
209 * @old_pad: the pad that has been removed
211 * a #GstPad has been removed from the element
213 gst_element_signals[PAD_REMOVED] =
214 g_signal_new ("pad-removed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
215 G_STRUCT_OFFSET (GstElementClass, pad_removed), NULL, NULL,
216 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
218 * GstElement::no-more-pads:
219 * @gstelement: the object which received the signal
221 * This signals that the element will not generate more dynamic pads.
222 * Note that this signal will usually be emitted from the context of
223 * the streaming thread.
225 gst_element_signals[NO_MORE_PADS] =
226 g_signal_new ("no-more-pads", G_TYPE_FROM_CLASS (klass),
227 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstElementClass, no_more_pads), NULL,
228 NULL, g_cclosure_marshal_generic, G_TYPE_NONE, 0);
230 gobject_class->dispose = gst_element_dispose;
231 gobject_class->finalize = gst_element_finalize;
233 klass->change_state = GST_DEBUG_FUNCPTR (gst_element_change_state_func);
234 klass->set_state = GST_DEBUG_FUNCPTR (gst_element_set_state_func);
235 klass->get_state = GST_DEBUG_FUNCPTR (gst_element_get_state_func);
236 klass->set_clock = GST_DEBUG_FUNCPTR (gst_element_set_clock_func);
237 klass->set_bus = GST_DEBUG_FUNCPTR (gst_element_set_bus_func);
238 klass->query = GST_DEBUG_FUNCPTR (gst_element_default_query);
239 klass->send_event = GST_DEBUG_FUNCPTR (gst_element_default_send_event);
240 klass->numpadtemplates = 0;
241 klass->post_message = GST_DEBUG_FUNCPTR (gst_element_post_message_default);
243 klass->elementfactory = NULL;
247 gst_element_base_class_init (gpointer g_class)
249 GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
250 GList *node, *padtemplates;
252 /* Copy the element details here so elements can inherit the
253 * details from their base class and classes only need to set
254 * the details in class_init instead of base_init */
255 element_class->metadata =
256 element_class->metadata ? gst_structure_copy (element_class->metadata) :
257 gst_structure_new_empty ("metadata");
259 /* Copy the pad templates so elements inherit them
260 * from their base class but elements can add pad templates in class_init
261 * instead of base_init.
263 padtemplates = g_list_copy (element_class->padtemplates);
264 for (node = padtemplates; node != NULL; node = node->next) {
265 GstPadTemplate *tmpl = (GstPadTemplate *) node->data;
266 gst_object_ref (tmpl);
268 element_class->padtemplates = padtemplates;
270 /* set the factory, see gst_element_register() */
271 element_class->elementfactory =
272 g_type_get_qdata (G_TYPE_FROM_CLASS (element_class),
273 __gst_elementclass_factory);
274 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "type %s : factory %p",
275 G_OBJECT_CLASS_NAME (element_class), element_class->elementfactory);
279 gst_element_base_class_finalize (gpointer g_class)
281 GstElementClass *klass = GST_ELEMENT_CLASS (g_class);
283 g_list_foreach (klass->padtemplates, (GFunc) gst_object_unref, NULL);
284 g_list_free (klass->padtemplates);
286 gst_structure_free (klass->metadata);
290 gst_element_init (GstElement * element)
292 GST_STATE (element) = GST_STATE_NULL;
293 GST_STATE_TARGET (element) = GST_STATE_NULL;
294 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
295 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
296 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
298 g_rec_mutex_init (&element->state_lock);
299 g_cond_init (&element->state_cond);
303 * gst_element_release_request_pad:
304 * @element: a #GstElement to release the request pad of.
305 * @pad: the #GstPad to release.
307 * Makes the element free the previously requested pad as obtained
308 * with gst_element_request_pad().
310 * This does not unref the pad. If the pad was created by using
311 * gst_element_request_pad(), gst_element_release_request_pad() needs to be
312 * followed by gst_object_unref() to free the @pad.
317 gst_element_release_request_pad (GstElement * element, GstPad * pad)
319 GstElementClass *oclass;
321 g_return_if_fail (GST_IS_ELEMENT (element));
322 g_return_if_fail (GST_IS_PAD (pad));
323 g_return_if_fail (GST_PAD_PAD_TEMPLATE (pad) == NULL ||
324 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad)) ==
327 oclass = GST_ELEMENT_GET_CLASS (element);
329 /* if the element implements a custom release function we call that, else we
330 * simply remove the pad from the element */
331 if (oclass->release_pad)
332 oclass->release_pad (element, pad);
334 gst_element_remove_pad (element, pad);
338 * gst_element_provide_clock:
339 * @element: a #GstElement to query
341 * Get the clock provided by the given element.
342 * <note>An element is only required to provide a clock in the PAUSED
343 * state. Some elements can provide a clock in other states.</note>
345 * Returns: (transfer full): the GstClock provided by the element or %NULL
346 * if no clock could be provided. Unref after usage.
351 gst_element_provide_clock (GstElement * element)
353 GstClock *result = NULL;
354 GstElementClass *oclass;
356 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
358 oclass = GST_ELEMENT_GET_CLASS (element);
360 if (oclass->provide_clock)
361 result = oclass->provide_clock (element);
367 gst_element_set_clock_func (GstElement * element, GstClock * clock)
371 GST_OBJECT_LOCK (element);
372 clock_p = &element->clock;
373 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
374 GST_OBJECT_UNLOCK (element);
380 * gst_element_set_clock:
381 * @element: a #GstElement to set the clock for.
382 * @clock: the #GstClock to set for the element.
384 * Sets the clock for the element. This function increases the
385 * refcount on the clock. Any previously set clock on the object
388 * Returns: %TRUE if the element accepted the clock. An element can refuse a
389 * clock when it, for example, is not able to slave its internal clock to the
390 * @clock or when it requires a specific clock to operate.
395 gst_element_set_clock (GstElement * element, GstClock * clock)
397 GstElementClass *oclass;
398 gboolean res = FALSE;
400 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
401 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
403 oclass = GST_ELEMENT_GET_CLASS (element);
405 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
407 if (oclass->set_clock)
408 res = oclass->set_clock (element, clock);
414 * gst_element_get_clock:
415 * @element: a #GstElement to get the clock of.
417 * Gets the currently configured clock of the element. This is the clock as was
418 * last set with gst_element_set_clock().
420 * Returns: (transfer full): the #GstClock of the element. unref after usage.
425 gst_element_get_clock (GstElement * element)
429 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
431 GST_OBJECT_LOCK (element);
432 if ((result = element->clock))
433 gst_object_ref (result);
434 GST_OBJECT_UNLOCK (element);
440 * gst_element_set_base_time:
441 * @element: a #GstElement.
442 * @time: the base time to set.
444 * Set the base time of an element. See gst_element_get_base_time().
449 gst_element_set_base_time (GstElement * element, GstClockTime time)
453 g_return_if_fail (GST_IS_ELEMENT (element));
455 GST_OBJECT_LOCK (element);
456 old = element->base_time;
457 element->base_time = time;
458 GST_OBJECT_UNLOCK (element);
460 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
461 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
462 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
466 * gst_element_get_base_time:
467 * @element: a #GstElement.
469 * Returns the base time of the element. The base time is the
470 * absolute time of the clock when this element was last put to
471 * PLAYING. Subtracting the base time from the clock time gives
472 * the running time of the element.
474 * Returns: the base time of the element.
479 gst_element_get_base_time (GstElement * element)
483 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
485 GST_OBJECT_LOCK (element);
486 result = element->base_time;
487 GST_OBJECT_UNLOCK (element);
493 * gst_element_set_start_time:
494 * @element: a #GstElement.
495 * @time: the base time to set.
497 * Set the start time of an element. The start time of the element is the
498 * running time of the element when it last went to the PAUSED state. In READY
499 * or after a flushing seek, it is set to 0.
501 * Toplevel elements like #GstPipeline will manage the start_time and
502 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
503 * on such a toplevel element will disable the distribution of the base_time to
504 * the children and can be useful if the application manages the base_time
505 * itself, for example if you want to synchronize capture from multiple
506 * pipelines, and you can also ensure that the pipelines have the same clock.
511 gst_element_set_start_time (GstElement * element, GstClockTime time)
515 g_return_if_fail (GST_IS_ELEMENT (element));
517 GST_OBJECT_LOCK (element);
518 old = GST_ELEMENT_START_TIME (element);
519 GST_ELEMENT_START_TIME (element) = time;
520 GST_OBJECT_UNLOCK (element);
522 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
523 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
524 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
528 * gst_element_get_start_time:
529 * @element: a #GstElement.
531 * Returns the start time of the element. The start time is the
532 * running time of the clock when this element was last put to PAUSED.
534 * Usually the start_time is managed by a toplevel element such as
539 * Returns: the start time of the element.
542 gst_element_get_start_time (GstElement * element)
546 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
548 GST_OBJECT_LOCK (element);
549 result = GST_ELEMENT_START_TIME (element);
550 GST_OBJECT_UNLOCK (element);
557 * gst_element_set_index:
558 * @element: a #GstElement.
559 * @index: (transfer none): a #GstIndex.
561 * Set @index on the element. The refcount of the index
562 * will be increased, any previously set index is unreffed.
567 gst_element_set_index (GstElement * element, GstIndex * index)
569 GstElementClass *oclass;
571 g_return_if_fail (GST_IS_ELEMENT (element));
572 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
574 oclass = GST_ELEMENT_GET_CLASS (element);
576 if (oclass->set_index)
577 oclass->set_index (element, index);
581 * gst_element_get_index:
582 * @element: a #GstElement.
584 * Gets the index from the element.
586 * Returns: (transfer full): a #GstIndex or %NULL when no index was set on the
587 * element. unref after usage.
592 gst_element_get_index (GstElement * element)
594 GstElementClass *oclass;
595 GstIndex *result = NULL;
597 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
599 oclass = GST_ELEMENT_GET_CLASS (element);
601 if (oclass->get_index)
602 result = oclass->get_index (element);
609 * gst_element_add_pad:
610 * @element: a #GstElement to add the pad to.
611 * @pad: (transfer full): the #GstPad to add to the element.
613 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
614 * see gst_object_set_parent() for refcounting information.
616 * Pads are not automatically activated so elements should perform the needed
617 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
618 * state. See gst_pad_set_active() for more information about activating pads.
620 * The pad and the element should be unlocked when calling this function.
622 * This function will emit the #GstElement::pad-added signal on the element.
624 * Returns: %TRUE if the pad could be added. This function can fail when
625 * a pad with the same name already existed or the pad already had another
631 gst_element_add_pad (GstElement * element, GstPad * pad)
636 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
637 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
639 /* locking pad to look at the name */
640 GST_OBJECT_LOCK (pad);
641 pad_name = g_strdup (GST_PAD_NAME (pad));
642 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
643 GST_STR_NULL (pad_name));
644 flushing = GST_PAD_IS_FLUSHING (pad);
645 GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_NEED_PARENT);
646 GST_OBJECT_UNLOCK (pad);
648 /* then check to see if there's already a pad by that name here */
649 GST_OBJECT_LOCK (element);
650 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
653 /* try to set the pad's parent */
654 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
655 GST_OBJECT_CAST (element))))
658 /* check for flushing pads */
659 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
660 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
661 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
662 "use gst_pad_set_active(pad,TRUE) before adding it.",
663 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
665 GST_OBJECT_LOCK (pad);
666 GST_PAD_UNSET_FLUSHING (pad);
667 GST_OBJECT_UNLOCK (pad);
672 /* add it to the list */
673 switch (gst_pad_get_direction (pad)) {
675 element->srcpads = g_list_append (element->srcpads, pad);
676 element->numsrcpads++;
679 element->sinkpads = g_list_append (element->sinkpads, pad);
680 element->numsinkpads++;
685 element->pads = g_list_append (element->pads, pad);
687 element->pads_cookie++;
688 GST_OBJECT_UNLOCK (element);
690 /* emit the PAD_ADDED signal */
691 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
698 g_critical ("Padname %s is not unique in element %s, not adding",
699 pad_name, GST_ELEMENT_NAME (element));
700 GST_OBJECT_UNLOCK (element);
707 ("Pad %s already has parent when trying to add to element %s",
708 pad_name, GST_ELEMENT_NAME (element));
709 GST_OBJECT_UNLOCK (element);
715 GST_OBJECT_LOCK (pad);
717 ("Trying to add pad %s to element %s, but it has no direction",
718 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
719 GST_OBJECT_UNLOCK (pad);
720 GST_OBJECT_UNLOCK (element);
726 * gst_element_remove_pad:
727 * @element: a #GstElement to remove pad from.
728 * @pad: (transfer full): the #GstPad to remove from the element.
730 * Removes @pad from @element. @pad will be destroyed if it has not been
731 * referenced elsewhere using gst_object_unparent().
733 * This function is used by plugin developers and should not be used
734 * by applications. Pads that were dynamically requested from elements
735 * with gst_element_request_pad() should be released with the
736 * gst_element_release_request_pad() function instead.
738 * Pads are not automatically deactivated so elements should perform the needed
739 * steps to deactivate the pad in case this pad is removed in the PAUSED or
740 * PLAYING state. See gst_pad_set_active() for more information about
743 * The pad and the element should be unlocked when calling this function.
745 * This function will emit the #GstElement::pad-removed signal on the element.
747 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
748 * pad does not belong to the provided element.
753 gst_element_remove_pad (GstElement * element, GstPad * pad)
757 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
758 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
760 /* locking pad to look at the name and parent */
761 GST_OBJECT_LOCK (pad);
762 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
763 GST_STR_NULL (GST_PAD_NAME (pad)));
765 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
767 GST_OBJECT_UNLOCK (pad);
770 if ((peer = gst_pad_get_peer (pad))) {
771 /* window for MT unsafeness, someone else could unlink here
772 * and then we call unlink with wrong pads. The unlink
773 * function would catch this and safely return failed. */
774 if (GST_PAD_IS_SRC (pad))
775 gst_pad_unlink (pad, peer);
777 gst_pad_unlink (peer, pad);
779 gst_object_unref (peer);
782 GST_OBJECT_LOCK (element);
783 /* remove it from the list */
784 switch (gst_pad_get_direction (pad)) {
786 element->srcpads = g_list_remove (element->srcpads, pad);
787 element->numsrcpads--;
790 element->sinkpads = g_list_remove (element->sinkpads, pad);
791 element->numsinkpads--;
794 g_critical ("Removing pad without direction???");
797 element->pads = g_list_remove (element->pads, pad);
799 element->pads_cookie++;
800 GST_OBJECT_UNLOCK (element);
802 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
803 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
805 gst_object_unparent (GST_OBJECT_CAST (pad));
812 /* locking order is element > pad */
813 GST_OBJECT_UNLOCK (pad);
815 GST_OBJECT_LOCK (element);
816 GST_OBJECT_LOCK (pad);
817 g_critical ("Padname %s:%s does not belong to element %s when removing",
818 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
819 GST_OBJECT_UNLOCK (pad);
820 GST_OBJECT_UNLOCK (element);
826 * gst_element_no_more_pads:
827 * @element: a #GstElement
829 * Use this function to signal that the element does not expect any more pads
830 * to show up in the current pipeline. This function should be called whenever
831 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
832 * pad templates use this in combination with autopluggers to figure out that
833 * the element is done initializing its pads.
835 * This function emits the #GstElement::no-more-pads signal.
840 gst_element_no_more_pads (GstElement * element)
842 g_return_if_fail (GST_IS_ELEMENT (element));
844 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
848 pad_compare_name (GstPad * pad1, const gchar * name)
852 GST_OBJECT_LOCK (pad1);
853 result = strcmp (GST_PAD_NAME (pad1), name);
854 GST_OBJECT_UNLOCK (pad1);
860 * gst_element_get_static_pad:
861 * @element: a #GstElement to find a static pad of.
862 * @name: the name of the static #GstPad to retrieve.
864 * Retrieves a pad from @element by name. This version only retrieves
865 * already-existing (i.e. 'static') pads.
867 * Returns: (transfer full): the requested #GstPad if found, otherwise %NULL.
873 gst_element_get_static_pad (GstElement * element, const gchar * name)
876 GstPad *result = NULL;
878 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
879 g_return_val_if_fail (name != NULL, NULL);
881 GST_OBJECT_LOCK (element);
883 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
885 result = GST_PAD_CAST (find->data);
886 gst_object_ref (result);
889 if (result == NULL) {
890 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
891 name, GST_ELEMENT_NAME (element));
893 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
894 GST_ELEMENT_NAME (element), name);
896 GST_OBJECT_UNLOCK (element);
902 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
903 const gchar * name, const GstCaps * caps)
905 GstPad *newpad = NULL;
906 GstElementClass *oclass;
908 oclass = GST_ELEMENT_GET_CLASS (element);
910 #ifndef G_DISABLE_CHECKS
911 /* Some sanity checking here */
915 /* Is this the template name? */
916 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
917 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
919 const gchar *str, *data;
922 /* Otherwise check if it's a valid name for the name template */
923 str = strchr (templ->name_template, '%');
924 g_return_val_if_fail (str != NULL, NULL);
925 g_return_val_if_fail (strncmp (templ->name_template, name,
926 str - templ->name_template) == 0, NULL);
927 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
929 data = name + (str - templ->name_template);
931 /* Can either be %s or %d or %u, do sanity checking for %d */
932 if (*(str + 1) == 'd') {
936 tmp = g_ascii_strtoll (data, &endptr, 10);
937 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
938 && *endptr == '\0', NULL);
939 } else if (*(str + 1) == 'u') {
943 tmp = g_ascii_strtoull (data, &endptr, 10);
944 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
948 pad = gst_element_get_static_pad (element, name);
950 gst_object_unref (pad);
951 /* FIXME 0.11: Change this to g_return_val_if_fail() */
952 g_critical ("Element %s already has a pad named %s, the behaviour of "
953 " gst_element_get_request_pad() for existing pads is undefined!",
954 GST_ELEMENT_NAME (element), name);
959 if (oclass->request_new_pad)
960 newpad = (oclass->request_new_pad) (element, templ, name, caps);
963 gst_object_ref (newpad);
969 * gst_element_get_request_pad:
970 * @element: a #GstElement to find a request pad of.
971 * @name: the name of the request #GstPad to retrieve.
973 * Retrieves a pad from the element by name (e.g. "src_\%d"). This version only
974 * retrieves request pads. The pad should be released with
975 * gst_element_release_request_pad().
977 * This method is slow and will be deprecated in the future. New code should
978 * use gst_element_request_pad() with the requested template.
980 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
981 * Release after usage.
984 gst_element_get_request_pad (GstElement * element, const gchar * name)
986 GstPadTemplate *templ = NULL;
988 const gchar *req_name = NULL;
989 gboolean templ_found = FALSE;
992 gchar *str, *endptr = NULL;
993 GstElementClass *class;
995 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
996 g_return_val_if_fail (name != NULL, NULL);
998 class = GST_ELEMENT_GET_CLASS (element);
1000 /* if the name contains a %, we assume it's the complete template name. Get
1001 * the template and try to get a pad */
1002 if (strstr (name, "%")) {
1003 templ = gst_element_class_get_request_pad_template (class, name);
1008 /* there is no % in the name, try to find a matching template */
1009 list = class->padtemplates;
1010 while (!templ_found && list) {
1011 templ = (GstPadTemplate *) list->data;
1012 if (templ->presence == GST_PAD_REQUEST) {
1013 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1014 templ->name_template);
1015 /* see if we find an exact match */
1016 if (strcmp (name, templ->name_template) == 0) {
1021 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1022 and %d and %u, occurring at the end of the name_template, are the only
1024 else if ((str = strchr (templ->name_template, '%'))
1025 && strncmp (templ->name_template, name,
1026 str - templ->name_template) == 0
1027 && strlen (name) > str - templ->name_template) {
1028 data = name + (str - templ->name_template);
1029 if (*(str + 1) == 'd') {
1033 tmp = strtol (data, &endptr, 10);
1034 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1040 } else if (*(str + 1) == 'u') {
1044 tmp = strtoul (data, &endptr, 10);
1045 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1065 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1071 * gst_element_request_pad:
1072 * @element: a #GstElement to find a request pad of.
1073 * @templ: a #GstPadTemplate of which we want a pad of.
1074 * @name: (transfer none) (allow-none): the name of the request #GstPad
1075 * to retrieve. Can be %NULL.
1076 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1077 * request. Can be %NULL.
1079 * Retrieves a request pad from the element according to the provided template.
1080 * Pad templates can be looked up using
1081 * gst_element_factory_get_static_pad_templates().
1083 * The pad should be released with gst_element_release_request_pad().
1085 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1086 * Release after usage.
1089 gst_element_request_pad (GstElement * element,
1090 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1092 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1093 g_return_val_if_fail (templ != NULL, NULL);
1094 g_return_val_if_fail (templ->presence == GST_PAD_REQUEST, NULL);
1096 return _gst_element_request_pad (element, templ, name, caps);
1099 static GstIterator *
1100 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1102 GstIterator *result;
1104 GST_OBJECT_LOCK (element);
1105 result = gst_iterator_new_list (GST_TYPE_PAD,
1106 GST_OBJECT_GET_LOCK (element),
1107 &element->pads_cookie, padlist, (GObject *) element, NULL);
1108 GST_OBJECT_UNLOCK (element);
1114 * gst_element_iterate_pads:
1115 * @element: a #GstElement to iterate pads of.
1117 * Retrieves an iterator of @element's pads. The iterator should
1118 * be freed after usage. Also more specialized iterators exists such as
1119 * gst_element_iterate_src_pads() or gst_element_iterate_sink_pads().
1121 * The order of pads returned by the iterator will be the order in which
1122 * the pads were added to the element.
1124 * Returns: (transfer full): the #GstIterator of #GstPad.
1129 gst_element_iterate_pads (GstElement * element)
1131 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1133 return gst_element_iterate_pad_list (element, &element->pads);
1137 * gst_element_iterate_src_pads:
1138 * @element: a #GstElement.
1140 * Retrieves an iterator of @element's source pads.
1142 * The order of pads returned by the iterator will be the order in which
1143 * the pads were added to the element.
1145 * Returns: (transfer full): the #GstIterator of #GstPad.
1150 gst_element_iterate_src_pads (GstElement * element)
1152 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1154 return gst_element_iterate_pad_list (element, &element->srcpads);
1158 * gst_element_iterate_sink_pads:
1159 * @element: a #GstElement.
1161 * Retrieves an iterator of @element's sink pads.
1163 * The order of pads returned by the iterator will be the order in which
1164 * the pads were added to the element.
1166 * Returns: (transfer full): the #GstIterator of #GstPad.
1171 gst_element_iterate_sink_pads (GstElement * element)
1173 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1175 return gst_element_iterate_pad_list (element, &element->sinkpads);
1179 * gst_element_class_add_pad_template:
1180 * @klass: the #GstElementClass to add the pad template to.
1181 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1183 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1184 * functions of classes. If a pad template with the same name as an already
1185 * existing one is added the old one is replaced by the new one.
1189 gst_element_class_add_pad_template (GstElementClass * klass,
1190 GstPadTemplate * templ)
1192 GList *template_list = klass->padtemplates;
1194 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1195 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1197 /* If we already have a pad template with the same name replace the
1199 while (template_list) {
1200 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1202 /* Found pad with the same name, replace and return */
1203 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1204 gst_object_unref (padtempl);
1205 template_list->data = templ;
1208 template_list = g_list_next (template_list);
1211 /* Take ownership of the floating ref */
1212 gst_object_ref_sink (templ);
1214 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1215 klass->numpadtemplates++;
1219 * gst_element_class_add_metadata:
1220 * @klass: class to set metadata for
1221 * @key: the key to set
1222 * @value: the value to set
1224 * Set @key with @value as metadata in @klass.
1227 gst_element_class_add_metadata (GstElementClass * klass,
1228 const gchar * key, const gchar * value)
1230 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1231 g_return_if_fail (key != NULL);
1232 g_return_if_fail (value != NULL);
1234 gst_structure_set ((GstStructure *) klass->metadata,
1235 key, G_TYPE_STRING, value, NULL);
1239 * gst_element_class_add_static_metadata:
1240 * @klass: class to set metadata for
1241 * @key: the key to set
1242 * @value: the value to set
1244 * Set @key with @value as metadata in @klass.
1246 * Same as gst_element_class_add_metadata(), but @value must be a static string
1247 * or an inlined string, as it will not be copied. (GStreamer plugins will
1248 * be made resident once loaded, so this function can be used even from
1249 * dynamically loaded plugins.)
1252 gst_element_class_add_static_metadata (GstElementClass * klass,
1253 const gchar * key, const gchar * value)
1255 GValue val = G_VALUE_INIT;
1257 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1258 g_return_if_fail (key != NULL);
1259 g_return_if_fail (value != NULL);
1261 g_value_init (&val, G_TYPE_STRING);
1262 g_value_set_static_string (&val, value);
1263 gst_structure_take_value ((GstStructure *) klass->metadata, key, &val);
1267 * gst_element_class_set_metadata:
1268 * @klass: class to set metadata for
1269 * @longname: The long English name of the element. E.g. "File Sink"
1270 * @classification: String describing the type of element, as an unordered list
1271 * separated with slashes ('/'). See draft-klass.txt of the design docs
1272 * for more details and common types. E.g: "Sink/File"
1273 * @description: Sentence describing the purpose of the element.
1274 * E.g: "Write stream to a file"
1275 * @author: Name and contact details of the author(s). Use \n to separate
1276 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1278 * Sets the detailed information for a #GstElementClass.
1279 * <note>This function is for use in _class_init functions only.</note>
1282 gst_element_class_set_metadata (GstElementClass * klass,
1283 const gchar * longname, const gchar * classification,
1284 const gchar * description, const gchar * author)
1286 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1287 g_return_if_fail (longname != NULL && *longname != '\0');
1288 g_return_if_fail (classification != NULL && *classification != '\0');
1289 g_return_if_fail (description != NULL && *description != '\0');
1290 g_return_if_fail (author != NULL && *author != '\0');
1292 gst_structure_id_set ((GstStructure *) klass->metadata,
1293 GST_QUARK (ELEMENT_METADATA_LONGNAME), G_TYPE_STRING, longname,
1294 GST_QUARK (ELEMENT_METADATA_KLASS), G_TYPE_STRING, classification,
1295 GST_QUARK (ELEMENT_METADATA_DESCRIPTION), G_TYPE_STRING, description,
1296 GST_QUARK (ELEMENT_METADATA_AUTHOR), G_TYPE_STRING, author, NULL);
1300 * gst_element_class_set_static_metadata:
1301 * @klass: class to set metadata for
1302 * @longname: The long English name of the element. E.g. "File Sink"
1303 * @classification: String describing the type of element, as an unordered list
1304 * separated with slashes ('/'). See draft-klass.txt of the design docs
1305 * for more details and common types. E.g: "Sink/File"
1306 * @description: Sentence describing the purpose of the element.
1307 * E.g: "Write stream to a file"
1308 * @author: Name and contact details of the author(s). Use \n to separate
1309 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1311 * Sets the detailed information for a #GstElementClass.
1312 * <note>This function is for use in _class_init functions only.</note>
1314 * Same as gst_element_class_set_metadata(), but @longname, @classification,
1315 * @description, and @author must be static strings or inlined strings, as
1316 * they will not be copied. (GStreamer plugins will be made resident once
1317 * loaded, so this function can be used even from dynamically loaded plugins.)
1320 gst_element_class_set_static_metadata (GstElementClass * klass,
1321 const gchar * longname, const gchar * classification,
1322 const gchar * description, const gchar * author)
1324 GstStructure *s = (GstStructure *) klass->metadata;
1325 GValue val = G_VALUE_INIT;
1327 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1328 g_return_if_fail (longname != NULL && *longname != '\0');
1329 g_return_if_fail (classification != NULL && *classification != '\0');
1330 g_return_if_fail (description != NULL && *description != '\0');
1331 g_return_if_fail (author != NULL && *author != '\0');
1333 g_value_init (&val, G_TYPE_STRING);
1335 g_value_set_static_string (&val, longname);
1336 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_LONGNAME), &val);
1338 g_value_set_static_string (&val, classification);
1339 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_KLASS), &val);
1341 g_value_set_static_string (&val, description);
1342 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_DESCRIPTION),
1345 g_value_set_static_string (&val, author);
1346 gst_structure_id_take_value (s, GST_QUARK (ELEMENT_METADATA_AUTHOR), &val);
1350 * gst_element_class_get_metadata:
1351 * @klass: class to get metadata for
1352 * @key: the key to get
1354 * Get metadata with @key in @klass.
1356 * Returns: the metadata for @key.
1359 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1361 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1362 g_return_val_if_fail (key != NULL, NULL);
1364 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1368 * gst_element_class_get_pad_template_list:
1369 * @element_class: a #GstElementClass to get pad templates of.
1371 * Retrieves a list of the pad templates associated with @element_class. The
1372 * list must not be modified by the calling code.
1373 * <note>If you use this function in the #GInstanceInitFunc of an object class
1374 * that has subclasses, make sure to pass the g_class parameter of the
1375 * #GInstanceInitFunc here.</note>
1377 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1381 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1383 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1385 return element_class->padtemplates;
1389 * gst_element_class_get_pad_template:
1390 * @element_class: a #GstElementClass to get the pad template of.
1391 * @name: the name of the #GstPadTemplate to get.
1393 * Retrieves a padtemplate from @element_class with the given name.
1394 * <note>If you use this function in the #GInstanceInitFunc of an object class
1395 * that has subclasses, make sure to pass the g_class parameter of the
1396 * #GInstanceInitFunc here.</note>
1398 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1399 * if none was found. No unreferencing is necessary.
1402 gst_element_class_get_pad_template (GstElementClass *
1403 element_class, const gchar * name)
1407 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1408 g_return_val_if_fail (name != NULL, NULL);
1410 padlist = element_class->padtemplates;
1413 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1415 if (strcmp (padtempl->name_template, name) == 0)
1418 padlist = g_list_next (padlist);
1424 static GstPadTemplate *
1425 gst_element_class_get_request_pad_template (GstElementClass *
1426 element_class, const gchar * name)
1428 GstPadTemplate *tmpl;
1430 tmpl = gst_element_class_get_pad_template (element_class, name);
1431 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1437 /* get a random pad on element of the given direction.
1438 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1441 gst_element_get_random_pad (GstElement * element,
1442 gboolean need_linked, GstPadDirection dir)
1444 GstPad *result = NULL;
1447 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1451 GST_OBJECT_LOCK (element);
1452 pads = element->srcpads;
1455 GST_OBJECT_LOCK (element);
1456 pads = element->sinkpads;
1459 goto wrong_direction;
1461 for (; pads; pads = g_list_next (pads)) {
1462 GstPad *pad = GST_PAD_CAST (pads->data);
1464 GST_OBJECT_LOCK (pad);
1465 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1466 GST_DEBUG_PAD_NAME (pad));
1468 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1469 /* if we require a linked pad, and it is not linked, continue the
1471 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1472 GST_DEBUG_PAD_NAME (pad));
1473 GST_OBJECT_UNLOCK (pad);
1476 /* found a pad, stop search */
1477 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1478 GST_DEBUG_PAD_NAME (pad));
1479 GST_OBJECT_UNLOCK (pad);
1485 gst_object_ref (result);
1487 GST_OBJECT_UNLOCK (element);
1491 /* ERROR handling */
1494 g_warning ("unknown pad direction %d", dir);
1500 gst_element_default_send_event (GstElement * element, GstEvent * event)
1502 gboolean result = FALSE;
1505 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1506 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1507 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1510 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1511 "pushing %s event to random %s pad %s:%s",
1512 GST_EVENT_TYPE_NAME (event),
1513 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1514 GST_DEBUG_PAD_NAME (pad));
1516 result = gst_pad_push_event (pad, event);
1517 gst_object_unref (pad);
1519 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1520 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1521 gst_event_unref (event);
1527 * gst_element_send_event:
1528 * @element: a #GstElement to send the event to.
1529 * @event: (transfer full): the #GstEvent to send to the element.
1531 * Sends an event to an element. If the element doesn't implement an
1532 * event handler, the event will be pushed on a random linked sink pad for
1533 * upstream events or a random linked source pad for downstream events.
1535 * This function takes ownership of the provided event so you should
1536 * gst_event_ref() it if you want to reuse the event after this call.
1540 * Returns: %TRUE if the event was handled. Events that trigger a preroll (such
1541 * as flushing seeks and steps) will emit %GST_MESSAGE_ASYNC_DONE.
1544 gst_element_send_event (GstElement * element, GstEvent * event)
1546 GstElementClass *oclass;
1547 gboolean result = FALSE;
1549 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1550 g_return_val_if_fail (event != NULL, FALSE);
1552 oclass = GST_ELEMENT_GET_CLASS (element);
1554 GST_STATE_LOCK (element);
1555 if (oclass->send_event) {
1556 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1557 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1558 result = oclass->send_event (element, event);
1560 GST_STATE_UNLOCK (element);
1567 * @element: a #GstElement to send the event to.
1568 * @rate: The new playback rate
1569 * @format: The format of the seek values
1570 * @flags: The optional seek flags.
1571 * @start_type: The type and flags for the new start position
1572 * @start: The value of the new start position
1573 * @stop_type: The type and flags for the new stop position
1574 * @stop: The value of the new stop position
1576 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1577 * the parameters. The seek event is sent to the element using
1578 * gst_element_send_event().
1582 * Returns: %TRUE if the event was handled. Flushing seeks will trigger a
1583 * preroll, which will emit %GST_MESSAGE_ASYNC_DONE.
1586 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1587 GstSeekFlags flags, GstSeekType start_type, gint64 start,
1588 GstSeekType stop_type, gint64 stop)
1593 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1596 gst_event_new_seek (rate, format, flags, start_type, start, stop_type,
1598 result = gst_element_send_event (element, event);
1604 gst_element_default_query (GstElement * element, GstQuery * query)
1606 gboolean result = FALSE;
1609 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1611 result = gst_pad_query (pad, query);
1613 gst_object_unref (pad);
1615 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1617 GstPad *peer = gst_pad_get_peer (pad);
1620 result = gst_pad_query (peer, query);
1622 gst_object_unref (peer);
1624 gst_object_unref (pad);
1631 * gst_element_query:
1632 * @element: a #GstElement to perform the query on.
1633 * @query: (transfer none): the #GstQuery.
1635 * Performs a query on the given element.
1637 * For elements that don't implement a query handler, this function
1638 * forwards the query to a random srcpad or to the peer of a
1639 * random linked sinkpad of this element.
1641 * Please note that some queries might need a running pipeline to work.
1643 * Returns: TRUE if the query could be performed.
1648 gst_element_query (GstElement * element, GstQuery * query)
1650 GstElementClass *klass;
1652 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1653 g_return_val_if_fail (query != NULL, FALSE);
1655 klass = GST_ELEMENT_GET_CLASS (element);
1657 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1658 GST_ELEMENT_NAME (element));
1659 return klass->query (element, query);
1666 gst_element_post_message_default (GstElement * element, GstMessage * message)
1669 gboolean result = FALSE;
1671 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1672 g_return_val_if_fail (message != NULL, FALSE);
1674 GST_OBJECT_LOCK (element);
1677 if (G_UNLIKELY (bus == NULL))
1680 gst_object_ref (bus);
1681 GST_OBJECT_UNLOCK (element);
1683 /* we release the element lock when posting the message so that any
1684 * (synchronous) message handlers can operate on the element */
1685 result = gst_bus_post (bus, message);
1686 gst_object_unref (bus);
1693 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1694 "not posting message %p: no bus", message);
1695 GST_OBJECT_UNLOCK (element);
1696 gst_message_unref (message);
1702 * gst_element_post_message:
1703 * @element: a #GstElement posting the message
1704 * @message: (transfer full): a #GstMessage to post
1706 * Post a message on the element's #GstBus. This function takes ownership of the
1707 * message; if you want to access the message after this call, you should add an
1708 * additional reference before calling.
1710 * Returns: %TRUE if the message was successfully posted. The function returns
1711 * %FALSE if the element did not have a bus.
1716 gst_element_post_message (GstElement * element, GstMessage * message)
1718 GstElementClass *klass;
1720 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1721 g_return_val_if_fail (message != NULL, FALSE);
1723 klass = GST_ELEMENT_GET_CLASS (element);
1724 if (klass->post_message)
1725 return klass->post_message (element, message);
1731 * _gst_element_error_printf:
1732 * @format: the printf-like format to use, or %NULL
1734 * This function is only used internally by the gst_element_error() macro.
1736 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1742 _gst_element_error_printf (const gchar * format, ...)
1753 va_start (args, format);
1755 len = __gst_vasprintf (&buffer, format, args);
1766 * gst_element_message_full:
1767 * @element: a #GstElement to send message from
1768 * @type: the #GstMessageType
1769 * @domain: the GStreamer GError domain this message belongs to
1770 * @code: the GError code belonging to the domain
1771 * @text: (allow-none) (transfer full): an allocated text string to be used
1772 * as a replacement for the default message connected to code,
1774 * @debug: (allow-none) (transfer full): an allocated debug message to be
1775 * used as a replacement for the default debugging information,
1777 * @file: the source code file where the error was generated
1778 * @function: the source code function where the error was generated
1779 * @line: the source code line where the error was generated
1781 * Post an error, warning or info message on the bus from inside an element.
1783 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1784 * #GST_MESSAGE_INFO.
1788 void gst_element_message_full
1789 (GstElement * element, GstMessageType type,
1790 GQuark domain, gint code, gchar * text,
1791 gchar * debug, const gchar * file, const gchar * function, gint line)
1793 GError *gerror = NULL;
1797 gboolean has_debug = TRUE;
1798 GstMessage *message = NULL;
1801 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1802 g_return_if_fail (GST_IS_ELEMENT (element));
1803 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1804 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1806 /* check if we send the given text or the default error text */
1807 if ((text == NULL) || (text[0] == 0)) {
1808 /* text could have come from g_strdup_printf (""); */
1810 sent_text = gst_error_get_message (domain, code);
1814 /* construct a sent_debug with extra information from source */
1815 if ((debug == NULL) || (debug[0] == 0)) {
1816 /* debug could have come from g_strdup_printf (""); */
1820 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1822 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1823 file, line, function, name, debug);
1825 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1826 file, line, function, name);
1830 /* create gerror and post message */
1831 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1833 gerror = g_error_new_literal (domain, code, sent_text);
1836 case GST_MESSAGE_ERROR:
1838 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1840 case GST_MESSAGE_WARNING:
1841 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1844 case GST_MESSAGE_INFO:
1845 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1849 g_assert_not_reached ();
1852 gst_element_post_message (element, message);
1854 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1855 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1858 g_error_free (gerror);
1859 g_free (sent_debug);
1864 * gst_element_is_locked_state:
1865 * @element: a #GstElement.
1867 * Checks if the state of an element is locked.
1868 * If the state of an element is locked, state changes of the parent don't
1869 * affect the element.
1870 * This way you can leave currently unused elements inside bins. Just lock their
1871 * state before changing the state from #GST_STATE_NULL.
1875 * Returns: TRUE, if the element's state is locked.
1878 gst_element_is_locked_state (GstElement * element)
1882 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1884 GST_OBJECT_LOCK (element);
1885 result = GST_ELEMENT_IS_LOCKED_STATE (element);
1886 GST_OBJECT_UNLOCK (element);
1892 * gst_element_set_locked_state:
1893 * @element: a #GstElement
1894 * @locked_state: TRUE to lock the element's state
1896 * Locks the state of an element, so state changes of the parent don't affect
1897 * this element anymore.
1901 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1902 * or the elements state-locking needed no change.
1905 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1909 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1911 GST_OBJECT_LOCK (element);
1912 old = GST_ELEMENT_IS_LOCKED_STATE (element);
1914 if (G_UNLIKELY (old == locked_state))
1918 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1919 GST_ELEMENT_NAME (element));
1920 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1922 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1923 GST_ELEMENT_NAME (element));
1924 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1926 GST_OBJECT_UNLOCK (element);
1932 GST_CAT_DEBUG (GST_CAT_STATES,
1933 "elements %s was already in locked state %d",
1934 GST_ELEMENT_NAME (element), old);
1935 GST_OBJECT_UNLOCK (element);
1942 * gst_element_sync_state_with_parent:
1943 * @element: a #GstElement.
1945 * Tries to change the state of the element to the same as its parent.
1946 * If this function returns FALSE, the state of element is undefined.
1948 * Returns: TRUE, if the element's state could be synced to the parent's state.
1953 gst_element_sync_state_with_parent (GstElement * element)
1957 GstStateChangeReturn ret;
1959 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1961 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1962 GstState parent_current, parent_pending;
1964 GST_OBJECT_LOCK (parent);
1965 parent_current = GST_STATE (parent);
1966 parent_pending = GST_STATE_PENDING (parent);
1967 GST_OBJECT_UNLOCK (parent);
1969 /* set to pending if there is one, else we set it to the current state of
1971 if (parent_pending != GST_STATE_VOID_PENDING)
1972 target = parent_pending;
1974 target = parent_current;
1976 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1977 "syncing state (%s) to parent %s %s (%s, %s)",
1978 gst_element_state_get_name (GST_STATE (element)),
1979 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1980 gst_element_state_get_name (parent_current),
1981 gst_element_state_get_name (parent_pending));
1983 ret = gst_element_set_state (element, target);
1984 if (ret == GST_STATE_CHANGE_FAILURE)
1987 gst_object_unref (parent);
1991 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
1998 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1999 "syncing state failed (%s)",
2000 gst_element_state_change_return_get_name (ret));
2001 gst_object_unref (parent);
2007 static GstStateChangeReturn
2008 gst_element_get_state_func (GstElement * element,
2009 GstState * state, GstState * pending, GstClockTime timeout)
2011 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2012 GstState old_pending;
2014 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2015 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2017 GST_OBJECT_LOCK (element);
2018 ret = GST_STATE_RETURN (element);
2019 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2020 gst_element_state_change_return_get_name (ret));
2022 /* we got an error, report immediately */
2023 if (ret == GST_STATE_CHANGE_FAILURE)
2026 /* we got no_preroll, report immediately */
2027 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2030 /* no need to wait async if we are not async */
2031 if (ret != GST_STATE_CHANGE_ASYNC)
2034 old_pending = GST_STATE_PENDING (element);
2035 if (old_pending != GST_STATE_VOID_PENDING) {
2039 /* get cookie to detect state changes during waiting */
2040 cookie = element->state_cookie;
2042 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2043 "waiting for element to commit state");
2045 /* we have a pending state change, wait for it to complete */
2046 if (timeout != GST_CLOCK_TIME_NONE) {
2048 /* make timeout absolute */
2049 end_time = g_get_monotonic_time () + (timeout / 1000);
2050 signaled = GST_STATE_WAIT_UNTIL (element, end_time);
2052 GST_STATE_WAIT (element);
2057 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2058 /* timeout triggered */
2059 ret = GST_STATE_CHANGE_ASYNC;
2061 if (cookie != element->state_cookie)
2064 /* could be success or failure */
2065 if (old_pending == GST_STATE (element)) {
2066 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2067 ret = GST_STATE_CHANGE_SUCCESS;
2069 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2070 ret = GST_STATE_CHANGE_FAILURE;
2073 /* if nothing is pending anymore we can return SUCCESS */
2074 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2075 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2076 ret = GST_STATE_CHANGE_SUCCESS;
2082 *state = GST_STATE (element);
2084 *pending = GST_STATE_PENDING (element);
2086 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2087 "state current: %s, pending: %s, result: %s",
2088 gst_element_state_get_name (GST_STATE (element)),
2089 gst_element_state_get_name (GST_STATE_PENDING (element)),
2090 gst_element_state_change_return_get_name (ret));
2091 GST_OBJECT_UNLOCK (element);
2098 *state = GST_STATE_VOID_PENDING;
2100 *pending = GST_STATE_VOID_PENDING;
2102 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2104 GST_OBJECT_UNLOCK (element);
2106 return GST_STATE_CHANGE_FAILURE;
2111 * gst_element_get_state:
2112 * @element: a #GstElement to get the state of.
2113 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2115 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2116 * state. Can be %NULL.
2117 * @timeout: a #GstClockTime to specify the timeout for an async
2118 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2120 * Gets the state of the element.
2122 * For elements that performed an ASYNC state change, as reported by
2123 * gst_element_set_state(), this function will block up to the
2124 * specified timeout value for the state change to complete.
2125 * If the element completes the state change or goes into
2126 * an error, this function returns immediately with a return value of
2127 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2129 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2130 * returns the current and pending state immediately.
2132 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2133 * successfully changed its state but is not able to provide data yet.
2134 * This mostly happens for live sources that only produce data in
2135 * %GST_STATE_PLAYING. While the state change return is equivalent to
2136 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2137 * some sink elements might not be able to complete their state change because
2138 * an element is not producing data to complete the preroll. When setting the
2139 * element to playing, the preroll will complete and playback will start.
2141 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2142 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2143 * element is still performing a state change or
2144 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2148 GstStateChangeReturn
2149 gst_element_get_state (GstElement * element,
2150 GstState * state, GstState * pending, GstClockTime timeout)
2152 GstElementClass *oclass;
2153 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2155 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2157 oclass = GST_ELEMENT_GET_CLASS (element);
2159 if (oclass->get_state)
2160 result = (oclass->get_state) (element, state, pending, timeout);
2166 * gst_element_abort_state:
2167 * @element: a #GstElement to abort the state of.
2169 * Abort the state change of the element. This function is used
2170 * by elements that do asynchronous state changes and find out
2171 * something is wrong.
2173 * This function should be called with the STATE_LOCK held.
2178 gst_element_abort_state (GstElement * element)
2182 #ifndef GST_DISABLE_GST_DEBUG
2186 g_return_if_fail (GST_IS_ELEMENT (element));
2188 GST_OBJECT_LOCK (element);
2189 pending = GST_STATE_PENDING (element);
2191 if (pending == GST_STATE_VOID_PENDING ||
2192 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2193 goto nothing_aborted;
2195 #ifndef GST_DISABLE_GST_DEBUG
2196 old_state = GST_STATE (element);
2198 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2199 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2200 gst_element_state_get_name (pending));
2204 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2206 GST_STATE_BROADCAST (element);
2207 GST_OBJECT_UNLOCK (element);
2213 GST_OBJECT_UNLOCK (element);
2218 /* Not static because GstBin has manual state handling too */
2220 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2221 GstState newstate, GstState pending)
2223 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2224 GstMessage *message;
2226 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2227 "notifying about state-changed %s to %s (%s pending)",
2228 gst_element_state_get_name (oldstate),
2229 gst_element_state_get_name (newstate),
2230 gst_element_state_get_name (pending));
2232 if (klass->state_changed)
2233 klass->state_changed (element, oldstate, newstate, pending);
2235 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2236 oldstate, newstate, pending);
2237 gst_element_post_message (element, message);
2241 * gst_element_continue_state:
2242 * @element: a #GstElement to continue the state change of.
2243 * @ret: The previous state return value
2245 * Commit the state change of the element and proceed to the next
2246 * pending state if any. This function is used
2247 * by elements that do asynchronous state changes.
2248 * The core will normally call this method automatically when an
2249 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2251 * If after calling this method the element still has not reached
2252 * the pending state, the next state change is performed.
2254 * This method is used internally and should normally not be called by plugins
2257 * Returns: The result of the commit state change.
2261 GstStateChangeReturn
2262 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2264 GstStateChangeReturn old_ret;
2265 GstState old_state, old_next;
2266 GstState current, next, pending;
2267 GstStateChange transition;
2269 GST_OBJECT_LOCK (element);
2270 old_ret = GST_STATE_RETURN (element);
2271 GST_STATE_RETURN (element) = ret;
2272 pending = GST_STATE_PENDING (element);
2274 /* check if there is something to commit */
2275 if (pending == GST_STATE_VOID_PENDING)
2276 goto nothing_pending;
2278 old_state = GST_STATE (element);
2279 /* this is the state we should go to next */
2280 old_next = GST_STATE_NEXT (element);
2281 /* update current state */
2282 current = GST_STATE (element) = old_next;
2284 /* see if we reached the final state */
2285 if (pending == current)
2288 next = GST_STATE_GET_NEXT (current, pending);
2289 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2291 GST_STATE_NEXT (element) = next;
2293 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2294 GST_OBJECT_UNLOCK (element);
2296 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2297 "committing state from %s to %s, pending %s, next %s",
2298 gst_element_state_get_name (old_state),
2299 gst_element_state_get_name (old_next),
2300 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2302 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2304 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2305 "continue state change %s to %s, final %s",
2306 gst_element_state_get_name (current),
2307 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2309 ret = gst_element_change_state (element, transition);
2315 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2316 GST_OBJECT_UNLOCK (element);
2321 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2322 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2324 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2325 "completed state change to %s", gst_element_state_get_name (pending));
2326 GST_OBJECT_UNLOCK (element);
2328 /* don't post silly messages with the same state. This can happen
2329 * when an element state is changed to what it already was. For bins
2330 * this can be the result of a lost state, which we check with the
2331 * previous return value.
2332 * We do signal the cond though as a _get_state() might be blocking
2334 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2335 _priv_gst_element_state_changed (element, old_state, old_next,
2336 GST_STATE_VOID_PENDING);
2338 GST_STATE_BROADCAST (element);
2345 * gst_element_lost_state:
2346 * @element: a #GstElement the state is lost of
2348 * Brings the element to the lost state. The current state of the
2349 * element is copied to the pending state so that any call to
2350 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2352 * An ASYNC_START message is posted. If the element was PLAYING, it will
2353 * go to PAUSED. The element will be restored to its PLAYING state by
2354 * the parent pipeline when it prerolls again.
2356 * This is mostly used for elements that lost their preroll buffer
2357 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2358 * they will go to their pending state again when a new preroll buffer is
2359 * queued. This function can only be called when the element is currently
2360 * not in error or an async state change.
2362 * This function is used internally and should normally not be called from
2363 * plugins or applications.
2366 gst_element_lost_state (GstElement * element)
2368 GstState old_state, new_state;
2369 GstMessage *message;
2371 g_return_if_fail (GST_IS_ELEMENT (element));
2373 GST_OBJECT_LOCK (element);
2374 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2377 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2378 goto only_async_start;
2380 old_state = GST_STATE (element);
2382 /* when we were PLAYING, the new state is PAUSED. We will also not
2383 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2384 * when we preroll. */
2385 if (old_state > GST_STATE_PAUSED)
2386 new_state = GST_STATE_PAUSED;
2388 new_state = old_state;
2390 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2391 "lost state of %s to %s", gst_element_state_get_name (old_state),
2392 gst_element_state_get_name (new_state));
2394 GST_STATE (element) = new_state;
2395 GST_STATE_NEXT (element) = new_state;
2396 GST_STATE_PENDING (element) = new_state;
2397 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2398 GST_OBJECT_UNLOCK (element);
2400 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2402 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2403 gst_element_post_message (element, message);
2409 GST_OBJECT_UNLOCK (element);
2414 GST_OBJECT_UNLOCK (element);
2416 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2417 gst_element_post_message (element, message);
2423 * gst_element_set_state:
2424 * @element: a #GstElement to change state of.
2425 * @state: the element's new #GstState.
2427 * Sets the state of the element. This function will try to set the
2428 * requested state by going through all the intermediary states and calling
2429 * the class's state change function for each.
2431 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2432 * element will perform the remainder of the state change asynchronously in
2434 * An application can use gst_element_get_state() to wait for the completion
2435 * of the state change or it can wait for a %GST_MESSAGE_ASYNC_DONE or
2436 * %GST_MESSAGE_STATE_CHANGED on the bus.
2438 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2439 * #GST_STATE_CHANGE_ASYNC.
2441 * Returns: Result of the state change using #GstStateChangeReturn.
2445 GstStateChangeReturn
2446 gst_element_set_state (GstElement * element, GstState state)
2448 GstElementClass *oclass;
2449 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2451 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2453 oclass = GST_ELEMENT_GET_CLASS (element);
2455 if (oclass->set_state)
2456 result = (oclass->set_state) (element, state);
2462 * default set state function, calculates the next state based
2463 * on current state and calls the change_state function
2465 static GstStateChangeReturn
2466 gst_element_set_state_func (GstElement * element, GstState state)
2468 GstState current, next, old_pending;
2469 GstStateChangeReturn ret;
2470 GstStateChange transition;
2471 GstStateChangeReturn old_ret;
2473 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2475 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2476 gst_element_state_get_name (state));
2478 /* state lock is taken to protect the set_state() and get_state()
2479 * procedures, it does not lock any variables. */
2480 GST_STATE_LOCK (element);
2482 /* now calculate how to get to the new state */
2483 GST_OBJECT_LOCK (element);
2484 old_ret = GST_STATE_RETURN (element);
2485 /* previous state change returned an error, remove all pending
2486 * and next states */
2487 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2488 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2489 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2490 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2493 current = GST_STATE (element);
2494 next = GST_STATE_NEXT (element);
2495 old_pending = GST_STATE_PENDING (element);
2497 /* this is the (new) state we should go to. TARGET is the last state we set on
2499 if (state != GST_STATE_TARGET (element)) {
2500 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2501 "setting target state to %s", gst_element_state_get_name (state));
2502 GST_STATE_TARGET (element) = state;
2503 /* increment state cookie so that we can track each state change. We only do
2504 * this if this is actually a new state change. */
2505 element->state_cookie++;
2507 GST_STATE_PENDING (element) = state;
2509 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2510 "current %s, old_pending %s, next %s, old return %s",
2511 gst_element_state_get_name (current),
2512 gst_element_state_get_name (old_pending),
2513 gst_element_state_get_name (next),
2514 gst_element_state_change_return_get_name (old_ret));
2516 /* if the element was busy doing a state change, we just update the
2517 * target state, it'll get to it async then. */
2518 if (old_pending != GST_STATE_VOID_PENDING) {
2519 /* upwards state change will happen ASYNC */
2520 if (old_pending <= state)
2522 /* element is going to this state already */
2523 else if (next == state)
2525 /* element was performing an ASYNC upward state change and
2526 * we request to go downward again. Start from the next pending
2528 else if (next > state
2529 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2533 next = GST_STATE_GET_NEXT (current, state);
2534 /* now we store the next state */
2535 GST_STATE_NEXT (element) = next;
2536 /* mark busy, we need to check that there is actually a state change
2537 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2538 * the default element change_state function has no way to know what the
2539 * old value was... could consider this a FIXME...*/
2540 if (current != next)
2541 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2543 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2545 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2546 "%s: setting state from %s to %s",
2547 (next != state ? "intermediate" : "final"),
2548 gst_element_state_get_name (current), gst_element_state_get_name (next));
2550 /* now signal any waiters, they will error since the cookie was incremented */
2551 GST_STATE_BROADCAST (element);
2553 GST_OBJECT_UNLOCK (element);
2555 ret = gst_element_change_state (element, transition);
2557 GST_STATE_UNLOCK (element);
2559 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2560 gst_element_state_change_return_get_name (ret));
2566 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2567 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2568 "element was busy with async state change");
2569 GST_OBJECT_UNLOCK (element);
2571 GST_STATE_UNLOCK (element);
2573 return GST_STATE_CHANGE_ASYNC;
2578 * gst_element_change_state:
2579 * @element: a #GstElement
2580 * @transition: the requested transition
2582 * Perform @transition on @element.
2584 * This function must be called with STATE_LOCK held and is mainly used
2587 * Returns: the #GstStateChangeReturn of the state transition.
2589 GstStateChangeReturn
2590 gst_element_change_state (GstElement * element, GstStateChange transition)
2592 GstElementClass *oclass;
2593 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2595 oclass = GST_ELEMENT_GET_CLASS (element);
2597 /* call the state change function so it can set the state */
2598 if (oclass->change_state)
2599 ret = (oclass->change_state) (element, transition);
2601 ret = GST_STATE_CHANGE_FAILURE;
2604 case GST_STATE_CHANGE_FAILURE:
2605 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2606 "have FAILURE change_state return");
2607 /* state change failure */
2608 gst_element_abort_state (element);
2610 case GST_STATE_CHANGE_ASYNC:
2614 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2615 "element will change state ASYNC");
2617 target = GST_STATE_TARGET (element);
2619 if (target > GST_STATE_READY)
2622 /* else we just continue the state change downwards */
2623 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2624 "forcing commit state %s <= %s",
2625 gst_element_state_get_name (target),
2626 gst_element_state_get_name (GST_STATE_READY));
2628 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2631 case GST_STATE_CHANGE_SUCCESS:
2632 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2633 "element changed state SUCCESS");
2634 /* we can commit the state now which will proceeed to
2636 ret = gst_element_continue_state (element, ret);
2638 case GST_STATE_CHANGE_NO_PREROLL:
2639 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2640 "element changed state NO_PREROLL");
2641 /* we can commit the state now which will proceeed to
2643 ret = gst_element_continue_state (element, ret);
2646 goto invalid_return;
2649 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2654 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2662 GST_OBJECT_LOCK (element);
2663 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2664 g_critical ("%s: unknown return value %d from a state change function",
2665 GST_ELEMENT_NAME (element), ret);
2667 /* we are in error now */
2668 ret = GST_STATE_CHANGE_FAILURE;
2669 GST_STATE_RETURN (element) = ret;
2670 GST_OBJECT_UNLOCK (element);
2676 /* gst_iterator_fold functions for pads_activate
2677 * Stop the iterator if activating one pad failed. */
2679 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2681 GstPad *pad = g_value_get_object (vpad);
2682 gboolean cont = TRUE;
2684 if (!(cont = gst_pad_set_active (pad, *active)))
2685 g_value_set_boolean (ret, FALSE);
2690 /* returns false on error or early cutout of the fold, true if all
2691 * pads in @iter were (de)activated successfully. */
2693 iterator_activate_fold_with_resync (GstIterator * iter,
2694 GstIteratorFoldFunction func, gpointer user_data)
2696 GstIteratorResult ires;
2699 /* no need to unset this later, it's just a boolean */
2700 g_value_init (&ret, G_TYPE_BOOLEAN);
2701 g_value_set_boolean (&ret, TRUE);
2704 ires = gst_iterator_fold (iter, func, &ret, user_data);
2706 case GST_ITERATOR_RESYNC:
2707 /* need to reset the result again */
2708 g_value_set_boolean (&ret, TRUE);
2709 gst_iterator_resync (iter);
2711 case GST_ITERATOR_DONE:
2712 /* all pads iterated, return collected value */
2715 /* iterator returned _ERROR or premature end with _OK,
2716 * mark an error and exit */
2717 g_value_set_boolean (&ret, FALSE);
2722 /* return collected value */
2723 return g_value_get_boolean (&ret);
2726 /* is called with STATE_LOCK
2728 * Pads are activated from source pads to sinkpads.
2731 gst_element_pads_activate (GstElement * element, gboolean active)
2736 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2737 "%s pads", active ? "activate" : "deactivate");
2739 iter = gst_element_iterate_src_pads (element);
2741 iterator_activate_fold_with_resync (iter,
2742 (GstIteratorFoldFunction) activate_pads, &active);
2743 gst_iterator_free (iter);
2744 if (G_UNLIKELY (!res))
2747 iter = gst_element_iterate_sink_pads (element);
2749 iterator_activate_fold_with_resync (iter,
2750 (GstIteratorFoldFunction) activate_pads, &active);
2751 gst_iterator_free (iter);
2752 if (G_UNLIKELY (!res))
2755 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2756 "pad %sactivation successful", active ? "" : "de");
2763 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2764 "pad %sactivation failed", active ? "" : "de");
2769 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2770 "sink pads_activate failed");
2775 /* is called with STATE_LOCK */
2776 static GstStateChangeReturn
2777 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2779 GstState state, next;
2780 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2782 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2784 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2785 next = GST_STATE_TRANSITION_NEXT (transition);
2787 /* if the element already is in the given state, we just return success */
2788 if (next == GST_STATE_VOID_PENDING || state == next)
2791 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2792 "default handler tries setting state from %s to %s (%04x)",
2793 gst_element_state_get_name (state),
2794 gst_element_state_get_name (next), transition);
2796 switch (transition) {
2797 case GST_STATE_CHANGE_NULL_TO_READY:
2799 case GST_STATE_CHANGE_READY_TO_PAUSED:
2800 if (!gst_element_pads_activate (element, TRUE)) {
2801 result = GST_STATE_CHANGE_FAILURE;
2804 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2806 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2808 case GST_STATE_CHANGE_PAUSED_TO_READY:
2809 case GST_STATE_CHANGE_READY_TO_NULL:
2810 /* deactivate pads in both cases, since they are activated on
2811 ready->paused but the element might not have made it to paused */
2812 if (!gst_element_pads_activate (element, FALSE)) {
2813 result = GST_STATE_CHANGE_FAILURE;
2817 /* this will catch real but unhandled state changes;
2818 * can only be caused by:
2819 * - a new state was added
2820 * - somehow the element was asked to jump across an intermediate state
2822 g_warning ("Unhandled state change from %s to %s",
2823 gst_element_state_get_name (state),
2824 gst_element_state_get_name (next));
2831 GST_OBJECT_LOCK (element);
2832 result = GST_STATE_RETURN (element);
2833 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2834 "element is already in the %s state",
2835 gst_element_state_get_name (state));
2836 GST_OBJECT_UNLOCK (element);
2843 * gst_element_get_factory:
2844 * @element: a #GstElement to request the element factory of.
2846 * Retrieves the factory that was used to create this element.
2848 * Returns: (transfer none): the #GstElementFactory used for creating this
2849 * element. no refcounting is needed.
2852 gst_element_get_factory (GstElement * element)
2854 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2856 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2860 gst_element_dispose (GObject * object)
2862 GstElement *element = GST_ELEMENT_CAST (object);
2865 GstElementClass *oclass;
2868 oclass = GST_ELEMENT_GET_CLASS (element);
2870 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2872 if (GST_STATE (element) != GST_STATE_NULL)
2875 /* start by releasing all request pads, this might also remove some dynamic
2877 walk = element->pads;
2879 GstPad *pad = GST_PAD_CAST (walk->data);
2883 if (oclass->release_pad && GST_PAD_PAD_TEMPLATE (pad) &&
2884 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
2885 == GST_PAD_REQUEST) {
2886 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2887 "removing request pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2888 oclass->release_pad (element, pad);
2890 /* in case the release_pad function removed the next pad too */
2891 if (walk && g_list_position (element->pads, walk) == -1)
2892 walk = element->pads;
2895 /* remove the remaining pads */
2896 while (element->pads) {
2897 GstPad *pad = GST_PAD_CAST (element->pads->data);
2898 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2899 "removing pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2900 if (!gst_element_remove_pad (element, pad)) {
2901 /* only happens when someone unparented our pad.. */
2902 g_critical ("failed to remove pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2907 GST_OBJECT_LOCK (element);
2908 clock_p = &element->clock;
2909 bus_p = &element->bus;
2910 gst_object_replace ((GstObject **) clock_p, NULL);
2911 gst_object_replace ((GstObject **) bus_p, NULL);
2912 GST_OBJECT_UNLOCK (element);
2914 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2916 G_OBJECT_CLASS (parent_class)->dispose (object);
2925 is_locked = GST_ELEMENT_IS_LOCKED_STATE (element);
2927 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2929 "You need to explicitly set elements to the NULL state before\n"
2930 "dropping the final reference, to allow them to clean up.\n"
2931 "This problem may also be caused by a refcounting bug in the\n"
2932 "application or some element.\n",
2933 GST_OBJECT_NAME (element),
2934 gst_element_state_get_name (GST_STATE (element)),
2935 is_locked ? " (locked)" : "");
2941 gst_element_finalize (GObject * object)
2943 GstElement *element = GST_ELEMENT_CAST (object);
2945 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2947 g_cond_clear (&element->state_cond);
2948 g_rec_mutex_clear (&element->state_lock);
2950 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2952 G_OBJECT_CLASS (parent_class)->finalize (object);
2956 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2960 g_return_if_fail (GST_IS_ELEMENT (element));
2962 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2964 GST_OBJECT_LOCK (element);
2965 bus_p = &GST_ELEMENT_BUS (element);
2966 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
2967 GST_OBJECT_UNLOCK (element);
2971 * gst_element_set_bus:
2972 * @element: a #GstElement to set the bus of.
2973 * @bus: (transfer none): the #GstBus to set.
2975 * Sets the bus of the element. Increases the refcount on the bus.
2976 * For internal use only, unless you're testing elements.
2981 gst_element_set_bus (GstElement * element, GstBus * bus)
2983 GstElementClass *oclass;
2985 g_return_if_fail (GST_IS_ELEMENT (element));
2987 oclass = GST_ELEMENT_GET_CLASS (element);
2989 if (oclass->set_bus)
2990 oclass->set_bus (element, bus);
2994 * gst_element_get_bus:
2995 * @element: a #GstElement to get the bus of.
2997 * Returns the bus of the element. Note that only a #GstPipeline will provide a
2998 * bus for the application.
3000 * Returns: (transfer full): the element's #GstBus. unref after usage.
3005 gst_element_get_bus (GstElement * element)
3007 GstBus *result = NULL;
3009 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3011 GST_OBJECT_LOCK (element);
3012 if ((result = GST_ELEMENT_BUS (element)))
3013 gst_object_ref (result);
3014 GST_OBJECT_UNLOCK (element);
3016 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,
3023 * gst_element_set_context:
3024 * @element: a #GstElement to set the context of.
3025 * @context: (transfer none): the #GstContext to set.
3027 * Sets the context of the element. Increases the refcount of the context.
3032 gst_element_set_context (GstElement * element, GstContext * context)
3034 GstElementClass *oclass;
3036 g_return_if_fail (GST_IS_ELEMENT (element));
3038 oclass = GST_ELEMENT_GET_CLASS (element);
3040 GST_CAT_DEBUG_OBJECT (GST_CAT_CONTEXT, element,
3041 "set context %p %" GST_PTR_FORMAT, context,
3042 gst_context_get_structure (context));
3044 if (oclass->set_context)
3045 oclass->set_context (element, context);