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 or
47 * gst_element_get_request_pad() with the template name such as "src_\%u".
48 * An iterator of all pads can be retrieved with gst_element_iterate_pads().
50 * Elements can be linked through their pads.
51 * If the link is straightforward, use the gst_element_link()
52 * convenience function to link two elements, or gst_element_link_many()
53 * for more elements in a row.
54 * Use gst_element_link_filtered() to link two elements constrained by
55 * a specified set of #GstCaps.
56 * For finer control, use gst_element_link_pads() and
57 * gst_element_link_pads_filtered() to specify the pads to link on
58 * each element by name.
60 * Each element has a state (see #GstState). You can get and set the state
61 * of an element with gst_element_get_state() and gst_element_set_state().
62 * Setting a state triggers a #GstStateChange. To get a string representation
63 * of a #GstState, use gst_element_state_get_name().
65 * You can get and set a #GstClock on an element using gst_element_get_clock()
66 * and gst_element_set_clock().
67 * Some elements can provide a clock for the pipeline if
68 * the #GST_ELEMENT_FLAG_PROVIDE_CLOCK flag is set. With the
69 * gst_element_provide_clock() method one can retrieve the clock provided by
71 * Not all elements require a clock to operate correctly. If the
72 * #GST_ELEMENT_FLAG_REQUIRE_CLOCK() flag is set, a clock should be set on the
73 * element with gst_element_set_clock().
75 * Note that clock slection and distribution is normally handled by the
76 * toplevel #GstPipeline so the clock functions are only to be used in very
77 * specific situations.
79 * Last reviewed on 2012-03-28 (0.11.3)
82 #include "gst_private.h"
85 #include <gobject/gvaluecollector.h>
87 #include "gstelement.h"
88 #include "gstelementmetadata.h"
89 #include "gstenumtypes.h"
97 #include "gst-i18n-lib.h"
98 #include "glib-compat-private.h"
100 /* Element signals and args */
116 static void gst_element_class_init (GstElementClass * klass);
117 static void gst_element_init (GstElement * element);
118 static void gst_element_base_class_init (gpointer g_class);
119 static void gst_element_base_class_finalize (gpointer g_class);
121 static void gst_element_dispose (GObject * object);
122 static void gst_element_finalize (GObject * object);
124 static GstStateChangeReturn gst_element_change_state_func (GstElement * element,
125 GstStateChange transition);
126 static GstStateChangeReturn gst_element_get_state_func (GstElement * element,
127 GstState * state, GstState * pending, GstClockTime timeout);
128 static GstStateChangeReturn gst_element_set_state_func (GstElement * element,
130 static gboolean gst_element_set_clock_func (GstElement * element,
132 static void gst_element_set_bus_func (GstElement * element, GstBus * bus);
133 static gboolean gst_element_post_message_default (GstElement * element,
134 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_get_request_pad().
310 * This does not unref the pad. If the pad was created by using
311 * gst_element_get_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_get_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. Unref each pad
1130 gst_element_iterate_pads (GstElement * element)
1132 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1134 return gst_element_iterate_pad_list (element, &element->pads);
1138 * gst_element_iterate_src_pads:
1139 * @element: a #GstElement.
1141 * Retrieves an iterator of @element's source pads.
1143 * The order of pads returned by the iterator will be the order in which
1144 * the pads were added to the element.
1146 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1152 gst_element_iterate_src_pads (GstElement * element)
1154 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1156 return gst_element_iterate_pad_list (element, &element->srcpads);
1160 * gst_element_iterate_sink_pads:
1161 * @element: a #GstElement.
1163 * Retrieves an iterator of @element's sink pads.
1165 * The order of pads returned by the iterator will be the order in which
1166 * the pads were added to the element.
1168 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1174 gst_element_iterate_sink_pads (GstElement * element)
1176 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1178 return gst_element_iterate_pad_list (element, &element->sinkpads);
1182 * gst_element_class_add_pad_template:
1183 * @klass: the #GstElementClass to add the pad template to.
1184 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1186 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1187 * functions of classes. If a pad template with the same name as an already
1188 * existing one is added the old one is replaced by the new one.
1192 gst_element_class_add_pad_template (GstElementClass * klass,
1193 GstPadTemplate * templ)
1195 GList *template_list = klass->padtemplates;
1197 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1198 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1200 /* If we already have a pad template with the same name replace the
1202 while (template_list) {
1203 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1205 /* Found pad with the same name, replace and return */
1206 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1207 gst_object_unref (padtempl);
1208 template_list->data = templ;
1211 template_list = g_list_next (template_list);
1214 /* Take ownership of the floating ref */
1215 gst_object_ref_sink (templ);
1217 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1218 klass->numpadtemplates++;
1222 * gst_element_class_add_metadata:
1223 * @klass: class to set metadata for
1224 * @key: the key to set
1225 * @value: the value to set
1227 * Set @key with @value as metadata in @klass.
1230 gst_element_class_add_metadata (GstElementClass * klass,
1231 const gchar * key, const gchar * value)
1233 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1234 g_return_if_fail (key != NULL);
1235 g_return_if_fail (value != NULL);
1237 gst_structure_set ((GstStructure *) klass->metadata,
1238 key, G_TYPE_STRING, value, NULL);
1242 * gst_element_class_add_static_metadata:
1243 * @klass: class to set metadata for
1244 * @key: the key to set
1245 * @value: the value to set
1247 * Set @key with @value as metadata in @klass.
1249 * Same as gst_element_class_add_metadata(), but @value must be a static string
1250 * or an inlined string, as it will not be copied. (GStreamer plugins will
1251 * be made resident once loaded, so this function can be used even from
1252 * dynamically loaded plugins.)
1255 gst_element_class_add_static_metadata (GstElementClass * klass,
1256 const gchar * key, const gchar * value)
1258 GValue val = G_VALUE_INIT;
1260 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1261 g_return_if_fail (key != NULL);
1262 g_return_if_fail (value != NULL);
1264 g_value_init (&val, G_TYPE_STRING);
1265 g_value_set_static_string (&val, value);
1266 gst_structure_take_value ((GstStructure *) klass->metadata, key, &val);
1270 * gst_element_class_set_metadata:
1271 * @klass: class to set metadata for
1272 * @longname: The long English name of the element. E.g. "File Sink"
1273 * @classification: String describing the type of element, as an unordered list
1274 * separated with slashes ('/'). See draft-klass.txt of the design docs
1275 * for more details and common types. E.g: "Sink/File"
1276 * @description: Sentence describing the purpose of the element.
1277 * E.g: "Write stream to a file"
1278 * @author: Name and contact details of the author(s). Use \n to separate
1279 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1281 * Sets the detailed information for a #GstElementClass.
1282 * <note>This function is for use in _class_init functions only.</note>
1285 gst_element_class_set_metadata (GstElementClass * klass,
1286 const gchar * longname, const gchar * classification,
1287 const gchar * description, const gchar * author)
1289 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1290 g_return_if_fail (longname != NULL && *longname != '\0');
1291 g_return_if_fail (classification != NULL && *classification != '\0');
1292 g_return_if_fail (description != NULL && *description != '\0');
1293 g_return_if_fail (author != NULL && *author != '\0');
1295 gst_structure_id_set ((GstStructure *) klass->metadata,
1296 GST_QUARK (ELEMENT_METADATA_LONGNAME), G_TYPE_STRING, longname,
1297 GST_QUARK (ELEMENT_METADATA_KLASS), G_TYPE_STRING, classification,
1298 GST_QUARK (ELEMENT_METADATA_DESCRIPTION), G_TYPE_STRING, description,
1299 GST_QUARK (ELEMENT_METADATA_AUTHOR), G_TYPE_STRING, author, NULL);
1303 * gst_element_class_set_static_metadata:
1304 * @klass: class to set metadata for
1305 * @longname: The long English name of the element. E.g. "File Sink"
1306 * @classification: String describing the type of element, as an unordered list
1307 * separated with slashes ('/'). See draft-klass.txt of the design docs
1308 * for more details and common types. E.g: "Sink/File"
1309 * @description: Sentence describing the purpose of the element.
1310 * E.g: "Write stream to a file"
1311 * @author: Name and contact details of the author(s). Use \n to separate
1312 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1314 * Sets the detailed information for a #GstElementClass.
1315 * <note>This function is for use in _class_init functions only.</note>
1317 * Same as gst_element_class_set_metadata(), but @longname, @classification,
1318 * @description, and @author must be static strings or inlined strings, as
1319 * they will not be copied. (GStreamer plugins will be made resident once
1320 * loaded, so this function can be used even from dynamically loaded plugins.)
1323 gst_element_class_set_static_metadata (GstElementClass * klass,
1324 const gchar * longname, const gchar * classification,
1325 const gchar * description, const gchar * author)
1327 GstStructure *s = (GstStructure *) klass->metadata;
1328 GValue val = G_VALUE_INIT;
1330 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1331 g_return_if_fail (longname != NULL && *longname != '\0');
1332 g_return_if_fail (classification != NULL && *classification != '\0');
1333 g_return_if_fail (description != NULL && *description != '\0');
1334 g_return_if_fail (author != NULL && *author != '\0');
1336 g_value_init (&val, G_TYPE_STRING);
1338 g_value_set_static_string (&val, longname);
1339 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_LONGNAME), &val);
1341 g_value_set_static_string (&val, classification);
1342 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_KLASS), &val);
1344 g_value_set_static_string (&val, description);
1345 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_DESCRIPTION),
1348 g_value_set_static_string (&val, author);
1349 gst_structure_id_take_value (s, GST_QUARK (ELEMENT_METADATA_AUTHOR), &val);
1353 * gst_element_class_get_metadata:
1354 * @klass: class to get metadata for
1355 * @key: the key to get
1357 * Get metadata with @key in @klass.
1359 * Returns: the metadata for @key.
1362 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1364 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1365 g_return_val_if_fail (key != NULL, NULL);
1367 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1371 * gst_element_class_get_pad_template_list:
1372 * @element_class: a #GstElementClass to get pad templates of.
1374 * Retrieves a list of the pad templates associated with @element_class. The
1375 * list must not be modified by the calling code.
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) (element-type Gst.PadTemplate): the #GList of
1384 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1386 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1388 return element_class->padtemplates;
1392 * gst_element_class_get_pad_template:
1393 * @element_class: a #GstElementClass to get the pad template of.
1394 * @name: the name of the #GstPadTemplate to get.
1396 * Retrieves a padtemplate from @element_class with the given name.
1397 * <note>If you use this function in the #GInstanceInitFunc of an object class
1398 * that has subclasses, make sure to pass the g_class parameter of the
1399 * #GInstanceInitFunc here.</note>
1401 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1402 * if none was found. No unreferencing is necessary.
1405 gst_element_class_get_pad_template (GstElementClass *
1406 element_class, const gchar * name)
1410 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1411 g_return_val_if_fail (name != NULL, NULL);
1413 padlist = element_class->padtemplates;
1416 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1418 if (strcmp (padtempl->name_template, name) == 0)
1421 padlist = g_list_next (padlist);
1427 static GstPadTemplate *
1428 gst_element_class_get_request_pad_template (GstElementClass *
1429 element_class, const gchar * name)
1431 GstPadTemplate *tmpl;
1433 tmpl = gst_element_class_get_pad_template (element_class, name);
1434 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1440 /* get a random pad on element of the given direction.
1441 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1444 gst_element_get_random_pad (GstElement * element,
1445 gboolean need_linked, GstPadDirection dir)
1447 GstPad *result = NULL;
1450 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1454 GST_OBJECT_LOCK (element);
1455 pads = element->srcpads;
1458 GST_OBJECT_LOCK (element);
1459 pads = element->sinkpads;
1462 goto wrong_direction;
1464 for (; pads; pads = g_list_next (pads)) {
1465 GstPad *pad = GST_PAD_CAST (pads->data);
1467 GST_OBJECT_LOCK (pad);
1468 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1469 GST_DEBUG_PAD_NAME (pad));
1471 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1472 /* if we require a linked pad, and it is not linked, continue the
1474 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1475 GST_DEBUG_PAD_NAME (pad));
1476 GST_OBJECT_UNLOCK (pad);
1479 /* found a pad, stop search */
1480 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1481 GST_DEBUG_PAD_NAME (pad));
1482 GST_OBJECT_UNLOCK (pad);
1488 gst_object_ref (result);
1490 GST_OBJECT_UNLOCK (element);
1494 /* ERROR handling */
1497 g_warning ("unknown pad direction %d", dir);
1503 gst_element_default_send_event (GstElement * element, GstEvent * event)
1505 gboolean result = FALSE;
1508 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1509 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1510 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1513 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1514 "pushing %s event to random %s pad %s:%s",
1515 GST_EVENT_TYPE_NAME (event),
1516 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1517 GST_DEBUG_PAD_NAME (pad));
1519 result = gst_pad_push_event (pad, event);
1520 gst_object_unref (pad);
1522 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1523 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1524 gst_event_unref (event);
1530 * gst_element_send_event:
1531 * @element: a #GstElement to send the event to.
1532 * @event: (transfer full): the #GstEvent to send to the element.
1534 * Sends an event to an element. If the element doesn't implement an
1535 * event handler, the event will be pushed on a random linked sink pad for
1536 * upstream events or a random linked source pad for downstream events.
1538 * This function takes owership of the provided event so you should
1539 * gst_event_ref() it if you want to reuse the event after this call.
1543 * Returns: %TRUE if the event was handled. Events that trigger a preroll (such
1544 * as flushing seeks and steps) will emit %GST_MESSAGE_ASYNC_DONE.
1547 gst_element_send_event (GstElement * element, GstEvent * event)
1549 GstElementClass *oclass;
1550 gboolean result = FALSE;
1552 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1553 g_return_val_if_fail (event != NULL, FALSE);
1555 oclass = GST_ELEMENT_GET_CLASS (element);
1557 GST_STATE_LOCK (element);
1558 if (oclass->send_event) {
1559 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1560 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1561 result = oclass->send_event (element, event);
1563 GST_STATE_UNLOCK (element);
1570 * @element: a #GstElement to send the event to.
1571 * @rate: The new playback rate
1572 * @format: The format of the seek values
1573 * @flags: The optional seek flags.
1574 * @start_type: The type and flags for the new start position
1575 * @start: The value of the new start position
1576 * @stop_type: The type and flags for the new stop position
1577 * @stop: The value of the new stop position
1579 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1580 * the parameters. The seek event is sent to the element using
1581 * gst_element_send_event().
1585 * Returns: %TRUE if the event was handled. Flushing seeks will trigger a
1586 * preroll, which will emit %GST_MESSAGE_ASYNC_DONE.
1589 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1590 GstSeekFlags flags, GstSeekType start_type, gint64 start,
1591 GstSeekType stop_type, gint64 stop)
1596 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1599 gst_event_new_seek (rate, format, flags, start_type, start, stop_type,
1601 result = gst_element_send_event (element, event);
1607 gst_element_default_query (GstElement * element, GstQuery * query)
1609 gboolean result = FALSE;
1612 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1614 result = gst_pad_query (pad, query);
1616 gst_object_unref (pad);
1618 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1620 GstPad *peer = gst_pad_get_peer (pad);
1623 result = gst_pad_query (peer, query);
1625 gst_object_unref (peer);
1627 gst_object_unref (pad);
1634 * gst_element_query:
1635 * @element: a #GstElement to perform the query on.
1636 * @query: (transfer none): the #GstQuery.
1638 * Performs a query on the given element.
1640 * For elements that don't implement a query handler, this function
1641 * forwards the query to a random srcpad or to the peer of a
1642 * random linked sinkpad of this element.
1644 * Please note that some queries might need a running pipeline to work.
1646 * Returns: TRUE if the query could be performed.
1651 gst_element_query (GstElement * element, GstQuery * query)
1653 GstElementClass *oclass;
1654 gboolean result = FALSE;
1656 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1657 g_return_val_if_fail (query != NULL, FALSE);
1659 oclass = GST_ELEMENT_GET_CLASS (element);
1661 if (oclass->query) {
1662 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1663 GST_ELEMENT_NAME (element));
1664 result = oclass->query (element, query);
1670 gst_element_post_message_default (GstElement * element, GstMessage * message)
1673 gboolean result = FALSE;
1675 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1676 g_return_val_if_fail (message != NULL, FALSE);
1678 GST_OBJECT_LOCK (element);
1681 if (G_UNLIKELY (bus == NULL))
1684 gst_object_ref (bus);
1685 GST_OBJECT_UNLOCK (element);
1687 /* we release the element lock when posting the message so that any
1688 * (synchronous) message handlers can operate on the element */
1689 result = gst_bus_post (bus, message);
1690 gst_object_unref (bus);
1697 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1698 "not posting message %p: no bus", message);
1699 GST_OBJECT_UNLOCK (element);
1700 gst_message_unref (message);
1706 * gst_element_post_message:
1707 * @element: a #GstElement posting the message
1708 * @message: (transfer full): a #GstMessage to post
1710 * Post a message on the element's #GstBus. This function takes ownership of the
1711 * message; if you want to access the message after this call, you should add an
1712 * additional reference before calling.
1714 * Returns: %TRUE if the message was successfully posted. The function returns
1715 * %FALSE if the element did not have a bus.
1720 gst_element_post_message (GstElement * element, GstMessage * message)
1722 GstElementClass *klass;
1724 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1726 klass = GST_ELEMENT_GET_CLASS (element);
1727 if (klass->post_message)
1728 return klass->post_message (element, message);
1734 * _gst_element_error_printf:
1735 * @format: the printf-like format to use, or %NULL
1737 * This function is only used internally by the gst_element_error() macro.
1739 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1745 _gst_element_error_printf (const gchar * format, ...)
1755 va_start (args, format);
1756 buffer = g_strdup_vprintf (format, args);
1762 * gst_element_message_full:
1763 * @element: a #GstElement to send message from
1764 * @type: the #GstMessageType
1765 * @domain: the GStreamer GError domain this message belongs to
1766 * @code: the GError code belonging to the domain
1767 * @text: (allow-none) (transfer full): an allocated text string to be used
1768 * as a replacement for the default message connected to code,
1770 * @debug: (allow-none) (transfer full): an allocated debug message to be
1771 * used as a replacement for the default debugging information,
1773 * @file: the source code file where the error was generated
1774 * @function: the source code function where the error was generated
1775 * @line: the source code line where the error was generated
1777 * Post an error, warning or info message on the bus from inside an element.
1779 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1780 * #GST_MESSAGE_INFO.
1784 void gst_element_message_full
1785 (GstElement * element, GstMessageType type,
1786 GQuark domain, gint code, gchar * text,
1787 gchar * debug, const gchar * file, const gchar * function, gint line)
1789 GError *gerror = NULL;
1793 gboolean has_debug = TRUE;
1794 GstMessage *message = NULL;
1797 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1798 g_return_if_fail (GST_IS_ELEMENT (element));
1799 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1800 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1802 /* check if we send the given text or the default error text */
1803 if ((text == NULL) || (text[0] == 0)) {
1804 /* text could have come from g_strdup_printf (""); */
1806 sent_text = gst_error_get_message (domain, code);
1810 /* construct a sent_debug with extra information from source */
1811 if ((debug == NULL) || (debug[0] == 0)) {
1812 /* debug could have come from g_strdup_printf (""); */
1816 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1818 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1819 file, line, function, name, debug);
1821 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1822 file, line, function, name);
1826 /* create gerror and post message */
1827 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1829 gerror = g_error_new_literal (domain, code, sent_text);
1832 case GST_MESSAGE_ERROR:
1834 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1836 case GST_MESSAGE_WARNING:
1837 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1840 case GST_MESSAGE_INFO:
1841 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1845 g_assert_not_reached ();
1848 gst_element_post_message (element, message);
1850 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1851 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1854 g_error_free (gerror);
1855 g_free (sent_debug);
1860 * gst_element_is_locked_state:
1861 * @element: a #GstElement.
1863 * Checks if the state of an element is locked.
1864 * If the state of an element is locked, state changes of the parent don't
1865 * affect the element.
1866 * This way you can leave currently unused elements inside bins. Just lock their
1867 * state before changing the state from #GST_STATE_NULL.
1871 * Returns: TRUE, if the element's state is locked.
1874 gst_element_is_locked_state (GstElement * element)
1878 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1880 GST_OBJECT_LOCK (element);
1881 result = GST_ELEMENT_IS_LOCKED_STATE (element);
1882 GST_OBJECT_UNLOCK (element);
1888 * gst_element_set_locked_state:
1889 * @element: a #GstElement
1890 * @locked_state: TRUE to lock the element's state
1892 * Locks the state of an element, so state changes of the parent don't affect
1893 * this element anymore.
1897 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1898 * or the elements state-locking needed no change.
1901 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1905 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1907 GST_OBJECT_LOCK (element);
1908 old = GST_ELEMENT_IS_LOCKED_STATE (element);
1910 if (G_UNLIKELY (old == locked_state))
1914 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1915 GST_ELEMENT_NAME (element));
1916 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1918 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1919 GST_ELEMENT_NAME (element));
1920 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1922 GST_OBJECT_UNLOCK (element);
1928 GST_CAT_DEBUG (GST_CAT_STATES,
1929 "elements %s was already in locked state %d",
1930 GST_ELEMENT_NAME (element), old);
1931 GST_OBJECT_UNLOCK (element);
1938 * gst_element_sync_state_with_parent:
1939 * @element: a #GstElement.
1941 * Tries to change the state of the element to the same as its parent.
1942 * If this function returns FALSE, the state of element is undefined.
1944 * Returns: TRUE, if the element's state could be synced to the parent's state.
1949 gst_element_sync_state_with_parent (GstElement * element)
1953 GstStateChangeReturn ret;
1955 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1957 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1958 GstState parent_current, parent_pending;
1960 GST_OBJECT_LOCK (parent);
1961 parent_current = GST_STATE (parent);
1962 parent_pending = GST_STATE_PENDING (parent);
1963 GST_OBJECT_UNLOCK (parent);
1965 /* set to pending if there is one, else we set it to the current state of
1967 if (parent_pending != GST_STATE_VOID_PENDING)
1968 target = parent_pending;
1970 target = parent_current;
1972 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1973 "syncing state (%s) to parent %s %s (%s, %s)",
1974 gst_element_state_get_name (GST_STATE (element)),
1975 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1976 gst_element_state_get_name (parent_current),
1977 gst_element_state_get_name (parent_pending));
1979 ret = gst_element_set_state (element, target);
1980 if (ret == GST_STATE_CHANGE_FAILURE)
1983 gst_object_unref (parent);
1987 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
1994 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1995 "syncing state failed (%s)",
1996 gst_element_state_change_return_get_name (ret));
1997 gst_object_unref (parent);
2003 static GstStateChangeReturn
2004 gst_element_get_state_func (GstElement * element,
2005 GstState * state, GstState * pending, GstClockTime timeout)
2007 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2008 GstState old_pending;
2010 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2011 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2013 GST_OBJECT_LOCK (element);
2014 ret = GST_STATE_RETURN (element);
2015 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2016 gst_element_state_change_return_get_name (ret));
2018 /* we got an error, report immediately */
2019 if (ret == GST_STATE_CHANGE_FAILURE)
2022 /* we got no_preroll, report immediately */
2023 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2026 /* no need to wait async if we are not async */
2027 if (ret != GST_STATE_CHANGE_ASYNC)
2030 old_pending = GST_STATE_PENDING (element);
2031 if (old_pending != GST_STATE_VOID_PENDING) {
2035 /* get cookie to detect state changes during waiting */
2036 cookie = element->state_cookie;
2038 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2039 "waiting for element to commit state");
2041 /* we have a pending state change, wait for it to complete */
2042 if (timeout != GST_CLOCK_TIME_NONE) {
2044 /* make timeout absolute */
2045 end_time = g_get_monotonic_time () + (timeout / 1000);
2046 signaled = GST_STATE_WAIT_UNTIL (element, end_time);
2048 GST_STATE_WAIT (element);
2053 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2054 /* timeout triggered */
2055 ret = GST_STATE_CHANGE_ASYNC;
2057 if (cookie != element->state_cookie)
2060 /* could be success or failure */
2061 if (old_pending == GST_STATE (element)) {
2062 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2063 ret = GST_STATE_CHANGE_SUCCESS;
2065 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2066 ret = GST_STATE_CHANGE_FAILURE;
2069 /* if nothing is pending anymore we can return SUCCESS */
2070 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2071 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2072 ret = GST_STATE_CHANGE_SUCCESS;
2078 *state = GST_STATE (element);
2080 *pending = GST_STATE_PENDING (element);
2082 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2083 "state current: %s, pending: %s, result: %s",
2084 gst_element_state_get_name (GST_STATE (element)),
2085 gst_element_state_get_name (GST_STATE_PENDING (element)),
2086 gst_element_state_change_return_get_name (ret));
2087 GST_OBJECT_UNLOCK (element);
2094 *state = GST_STATE_VOID_PENDING;
2096 *pending = GST_STATE_VOID_PENDING;
2098 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2100 GST_OBJECT_UNLOCK (element);
2102 return GST_STATE_CHANGE_FAILURE;
2107 * gst_element_get_state:
2108 * @element: a #GstElement to get the state of.
2109 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2111 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2112 * state. Can be %NULL.
2113 * @timeout: a #GstClockTime to specify the timeout for an async
2114 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2116 * Gets the state of the element.
2118 * For elements that performed an ASYNC state change, as reported by
2119 * gst_element_set_state(), this function will block up to the
2120 * specified timeout value for the state change to complete.
2121 * If the element completes the state change or goes into
2122 * an error, this function returns immediately with a return value of
2123 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2125 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2126 * returns the current and pending state immediately.
2128 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2129 * successfully changed its state but is not able to provide data yet.
2130 * This mostly happens for live sources that only produce data in
2131 * %GST_STATE_PLAYING. While the state change return is equivalent to
2132 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2133 * some sink elements might not be able to complete their state change because
2134 * an element is not producing data to complete the preroll. When setting the
2135 * element to playing, the preroll will complete and playback will start.
2137 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2138 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2139 * element is still performing a state change or
2140 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2144 GstStateChangeReturn
2145 gst_element_get_state (GstElement * element,
2146 GstState * state, GstState * pending, GstClockTime timeout)
2148 GstElementClass *oclass;
2149 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2151 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2153 oclass = GST_ELEMENT_GET_CLASS (element);
2155 if (oclass->get_state)
2156 result = (oclass->get_state) (element, state, pending, timeout);
2162 * gst_element_abort_state:
2163 * @element: a #GstElement to abort the state of.
2165 * Abort the state change of the element. This function is used
2166 * by elements that do asynchronous state changes and find out
2167 * something is wrong.
2169 * This function should be called with the STATE_LOCK held.
2174 gst_element_abort_state (GstElement * element)
2178 #ifndef GST_DISABLE_GST_DEBUG
2182 g_return_if_fail (GST_IS_ELEMENT (element));
2184 GST_OBJECT_LOCK (element);
2185 pending = GST_STATE_PENDING (element);
2187 if (pending == GST_STATE_VOID_PENDING ||
2188 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2189 goto nothing_aborted;
2191 #ifndef GST_DISABLE_GST_DEBUG
2192 old_state = GST_STATE (element);
2194 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2195 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2196 gst_element_state_get_name (pending));
2200 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2202 GST_STATE_BROADCAST (element);
2203 GST_OBJECT_UNLOCK (element);
2209 GST_OBJECT_UNLOCK (element);
2214 /* Not static because GstBin has manual state handling too */
2216 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2217 GstState newstate, GstState pending)
2219 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2220 GstMessage *message;
2222 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2223 "notifying about state-changed %s to %s (%s pending)",
2224 gst_element_state_get_name (oldstate),
2225 gst_element_state_get_name (newstate),
2226 gst_element_state_get_name (pending));
2228 if (klass->state_changed)
2229 klass->state_changed (element, oldstate, newstate, pending);
2231 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2232 oldstate, newstate, pending);
2233 gst_element_post_message (element, message);
2237 * gst_element_continue_state:
2238 * @element: a #GstElement to continue the state change of.
2239 * @ret: The previous state return value
2241 * Commit the state change of the element and proceed to the next
2242 * pending state if any. This function is used
2243 * by elements that do asynchronous state changes.
2244 * The core will normally call this method automatically when an
2245 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2247 * If after calling this method the element still has not reached
2248 * the pending state, the next state change is performed.
2250 * This method is used internally and should normally not be called by plugins
2253 * Returns: The result of the commit state change.
2257 GstStateChangeReturn
2258 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2260 GstStateChangeReturn old_ret;
2261 GstState old_state, old_next;
2262 GstState current, next, pending;
2263 GstStateChange transition;
2265 GST_OBJECT_LOCK (element);
2266 old_ret = GST_STATE_RETURN (element);
2267 GST_STATE_RETURN (element) = ret;
2268 pending = GST_STATE_PENDING (element);
2270 /* check if there is something to commit */
2271 if (pending == GST_STATE_VOID_PENDING)
2272 goto nothing_pending;
2274 old_state = GST_STATE (element);
2275 /* this is the state we should go to next */
2276 old_next = GST_STATE_NEXT (element);
2277 /* update current state */
2278 current = GST_STATE (element) = old_next;
2280 /* see if we reached the final state */
2281 if (pending == current)
2284 next = GST_STATE_GET_NEXT (current, pending);
2285 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2287 GST_STATE_NEXT (element) = next;
2289 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2290 GST_OBJECT_UNLOCK (element);
2292 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2293 "committing state from %s to %s, pending %s, next %s",
2294 gst_element_state_get_name (old_state),
2295 gst_element_state_get_name (old_next),
2296 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2298 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2300 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2301 "continue state change %s to %s, final %s",
2302 gst_element_state_get_name (current),
2303 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2305 ret = gst_element_change_state (element, transition);
2311 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2312 GST_OBJECT_UNLOCK (element);
2317 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2318 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2320 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2321 "completed state change to %s", gst_element_state_get_name (pending));
2322 GST_OBJECT_UNLOCK (element);
2324 /* don't post silly messages with the same state. This can happen
2325 * when an element state is changed to what it already was. For bins
2326 * this can be the result of a lost state, which we check with the
2327 * previous return value.
2328 * We do signal the cond though as a _get_state() might be blocking
2330 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2331 _priv_gst_element_state_changed (element, old_state, old_next,
2332 GST_STATE_VOID_PENDING);
2334 GST_STATE_BROADCAST (element);
2341 * gst_element_lost_state:
2342 * @element: a #GstElement the state is lost of
2344 * Brings the element to the lost state. The current state of the
2345 * element is copied to the pending state so that any call to
2346 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2348 * An ASYNC_START message is posted. If the element was PLAYING, it will
2349 * go to PAUSED. The element will be restored to its PLAYING state by
2350 * the parent pipeline when it prerolls again.
2352 * This is mostly used for elements that lost their preroll buffer
2353 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2354 * they will go to their pending state again when a new preroll buffer is
2355 * queued. This function can only be called when the element is currently
2356 * not in error or an async state change.
2358 * This function is used internally and should normally not be called from
2359 * plugins or applications.
2362 gst_element_lost_state (GstElement * element)
2364 GstState old_state, new_state;
2365 GstMessage *message;
2367 g_return_if_fail (GST_IS_ELEMENT (element));
2369 GST_OBJECT_LOCK (element);
2370 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2373 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2374 goto only_async_start;
2376 old_state = GST_STATE (element);
2378 /* when we were PLAYING, the new state is PAUSED. We will also not
2379 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2380 * when we preroll. */
2381 if (old_state > GST_STATE_PAUSED)
2382 new_state = GST_STATE_PAUSED;
2384 new_state = old_state;
2386 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2387 "lost state of %s to %s", gst_element_state_get_name (old_state),
2388 gst_element_state_get_name (new_state));
2390 GST_STATE (element) = new_state;
2391 GST_STATE_NEXT (element) = new_state;
2392 GST_STATE_PENDING (element) = new_state;
2393 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2394 GST_OBJECT_UNLOCK (element);
2396 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2398 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2399 gst_element_post_message (element, message);
2405 GST_OBJECT_UNLOCK (element);
2410 GST_OBJECT_UNLOCK (element);
2412 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2413 gst_element_post_message (element, message);
2419 * gst_element_set_state:
2420 * @element: a #GstElement to change state of.
2421 * @state: the element's new #GstState.
2423 * Sets the state of the element. This function will try to set the
2424 * requested state by going through all the intermediary states and calling
2425 * the class's state change function for each.
2427 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2428 * element will perform the remainder of the state change asynchronously in
2430 * An application can use gst_element_get_state() to wait for the completion
2431 * of the state change or it can wait for a state change message on the bus.
2433 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2434 * #GST_STATE_CHANGE_ASYNC.
2436 * Returns: Result of the state change using #GstStateChangeReturn.
2440 GstStateChangeReturn
2441 gst_element_set_state (GstElement * element, GstState state)
2443 GstElementClass *oclass;
2444 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2446 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2448 oclass = GST_ELEMENT_GET_CLASS (element);
2450 if (oclass->set_state)
2451 result = (oclass->set_state) (element, state);
2457 * default set state function, calculates the next state based
2458 * on current state and calls the change_state function
2460 static GstStateChangeReturn
2461 gst_element_set_state_func (GstElement * element, GstState state)
2463 GstState current, next, old_pending;
2464 GstStateChangeReturn ret;
2465 GstStateChange transition;
2466 GstStateChangeReturn old_ret;
2468 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2470 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2471 gst_element_state_get_name (state));
2473 /* state lock is taken to protect the set_state() and get_state()
2474 * procedures, it does not lock any variables. */
2475 GST_STATE_LOCK (element);
2477 /* now calculate how to get to the new state */
2478 GST_OBJECT_LOCK (element);
2479 old_ret = GST_STATE_RETURN (element);
2480 /* previous state change returned an error, remove all pending
2481 * and next states */
2482 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2483 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2484 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2485 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2488 current = GST_STATE (element);
2489 next = GST_STATE_NEXT (element);
2490 old_pending = GST_STATE_PENDING (element);
2492 /* this is the (new) state we should go to. TARGET is the last state we set on
2494 if (state != GST_STATE_TARGET (element)) {
2495 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2496 "setting target state to %s", gst_element_state_get_name (state));
2497 GST_STATE_TARGET (element) = state;
2498 /* increment state cookie so that we can track each state change. We only do
2499 * this if this is actually a new state change. */
2500 element->state_cookie++;
2502 GST_STATE_PENDING (element) = state;
2504 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2505 "current %s, old_pending %s, next %s, old return %s",
2506 gst_element_state_get_name (current),
2507 gst_element_state_get_name (old_pending),
2508 gst_element_state_get_name (next),
2509 gst_element_state_change_return_get_name (old_ret));
2511 /* if the element was busy doing a state change, we just update the
2512 * target state, it'll get to it async then. */
2513 if (old_pending != GST_STATE_VOID_PENDING) {
2514 /* upwards state change will happen ASYNC */
2515 if (old_pending <= state)
2517 /* element is going to this state already */
2518 else if (next == state)
2520 /* element was performing an ASYNC upward state change and
2521 * we request to go downward again. Start from the next pending
2523 else if (next > state
2524 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2528 next = GST_STATE_GET_NEXT (current, state);
2529 /* now we store the next state */
2530 GST_STATE_NEXT (element) = next;
2531 /* mark busy, we need to check that there is actually a state change
2532 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2533 * the default element change_state function has no way to know what the
2534 * old value was... could consider this a FIXME...*/
2535 if (current != next)
2536 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2538 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2540 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2541 "%s: setting state from %s to %s",
2542 (next != state ? "intermediate" : "final"),
2543 gst_element_state_get_name (current), gst_element_state_get_name (next));
2545 /* now signal any waiters, they will error since the cookie was incremented */
2546 GST_STATE_BROADCAST (element);
2548 GST_OBJECT_UNLOCK (element);
2550 ret = gst_element_change_state (element, transition);
2552 GST_STATE_UNLOCK (element);
2554 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2555 gst_element_state_change_return_get_name (ret));
2561 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2562 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2563 "element was busy with async state change");
2564 GST_OBJECT_UNLOCK (element);
2566 GST_STATE_UNLOCK (element);
2568 return GST_STATE_CHANGE_ASYNC;
2573 * gst_element_change_state:
2574 * @element: a #GstElement
2575 * @transition: the requested transition
2577 * Perform @transition on @element.
2579 * This function must be called with STATE_LOCK held and is mainly used
2582 * Returns: the #GstStateChangeReturn of the state transition.
2584 GstStateChangeReturn
2585 gst_element_change_state (GstElement * element, GstStateChange transition)
2587 GstElementClass *oclass;
2588 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2590 oclass = GST_ELEMENT_GET_CLASS (element);
2592 /* call the state change function so it can set the state */
2593 if (oclass->change_state)
2594 ret = (oclass->change_state) (element, transition);
2596 ret = GST_STATE_CHANGE_FAILURE;
2599 case GST_STATE_CHANGE_FAILURE:
2600 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2601 "have FAILURE change_state return");
2602 /* state change failure */
2603 gst_element_abort_state (element);
2605 case GST_STATE_CHANGE_ASYNC:
2609 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2610 "element will change state ASYNC");
2612 target = GST_STATE_TARGET (element);
2614 if (target > GST_STATE_READY)
2617 /* else we just continue the state change downwards */
2618 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2619 "forcing commit state %s <= %s",
2620 gst_element_state_get_name (target),
2621 gst_element_state_get_name (GST_STATE_READY));
2623 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2626 case GST_STATE_CHANGE_SUCCESS:
2627 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2628 "element changed state SUCCESS");
2629 /* we can commit the state now which will proceeed to
2631 ret = gst_element_continue_state (element, ret);
2633 case GST_STATE_CHANGE_NO_PREROLL:
2634 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2635 "element changed state NO_PREROLL");
2636 /* we can commit the state now which will proceeed to
2638 ret = gst_element_continue_state (element, ret);
2641 goto invalid_return;
2644 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2649 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2657 GST_OBJECT_LOCK (element);
2658 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2659 g_critical ("%s: unknown return value %d from a state change function",
2660 GST_ELEMENT_NAME (element), ret);
2662 /* we are in error now */
2663 ret = GST_STATE_CHANGE_FAILURE;
2664 GST_STATE_RETURN (element) = ret;
2665 GST_OBJECT_UNLOCK (element);
2671 /* gst_iterator_fold functions for pads_activate
2672 * Stop the iterator if activating one pad failed. */
2674 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2676 GstPad *pad = g_value_get_object (vpad);
2677 gboolean cont = TRUE;
2679 if (!(cont = gst_pad_set_active (pad, *active)))
2680 g_value_set_boolean (ret, FALSE);
2685 /* returns false on error or early cutout of the fold, true if all
2686 * pads in @iter were (de)activated successfully. */
2688 iterator_activate_fold_with_resync (GstIterator * iter,
2689 GstIteratorFoldFunction func, gpointer user_data)
2691 GstIteratorResult ires;
2694 /* no need to unset this later, it's just a boolean */
2695 g_value_init (&ret, G_TYPE_BOOLEAN);
2696 g_value_set_boolean (&ret, TRUE);
2699 ires = gst_iterator_fold (iter, func, &ret, user_data);
2701 case GST_ITERATOR_RESYNC:
2702 /* need to reset the result again */
2703 g_value_set_boolean (&ret, TRUE);
2704 gst_iterator_resync (iter);
2706 case GST_ITERATOR_DONE:
2707 /* all pads iterated, return collected value */
2710 /* iterator returned _ERROR or premature end with _OK,
2711 * mark an error and exit */
2712 g_value_set_boolean (&ret, FALSE);
2717 /* return collected value */
2718 return g_value_get_boolean (&ret);
2721 /* is called with STATE_LOCK
2723 * Pads are activated from source pads to sinkpads.
2726 gst_element_pads_activate (GstElement * element, gboolean active)
2731 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2732 "%s pads", active ? "activate" : "deactivate");
2734 iter = gst_element_iterate_src_pads (element);
2736 iterator_activate_fold_with_resync (iter,
2737 (GstIteratorFoldFunction) activate_pads, &active);
2738 gst_iterator_free (iter);
2739 if (G_UNLIKELY (!res))
2742 iter = gst_element_iterate_sink_pads (element);
2744 iterator_activate_fold_with_resync (iter,
2745 (GstIteratorFoldFunction) activate_pads, &active);
2746 gst_iterator_free (iter);
2747 if (G_UNLIKELY (!res))
2750 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2751 "pad %sactivation successful", active ? "" : "de");
2758 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2759 "pad %sactivation failed", active ? "" : "de");
2764 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2765 "sink pads_activate failed");
2770 /* is called with STATE_LOCK */
2771 static GstStateChangeReturn
2772 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2774 GstState state, next;
2775 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2777 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2779 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2780 next = GST_STATE_TRANSITION_NEXT (transition);
2782 /* if the element already is in the given state, we just return success */
2783 if (next == GST_STATE_VOID_PENDING || state == next)
2786 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2787 "default handler tries setting state from %s to %s (%04x)",
2788 gst_element_state_get_name (state),
2789 gst_element_state_get_name (next), transition);
2791 switch (transition) {
2792 case GST_STATE_CHANGE_NULL_TO_READY:
2794 case GST_STATE_CHANGE_READY_TO_PAUSED:
2795 if (!gst_element_pads_activate (element, TRUE)) {
2796 result = GST_STATE_CHANGE_FAILURE;
2799 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2801 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2803 case GST_STATE_CHANGE_PAUSED_TO_READY:
2804 case GST_STATE_CHANGE_READY_TO_NULL:
2805 /* deactivate pads in both cases, since they are activated on
2806 ready->paused but the element might not have made it to paused */
2807 if (!gst_element_pads_activate (element, FALSE)) {
2808 result = GST_STATE_CHANGE_FAILURE;
2812 /* this will catch real but unhandled state changes;
2813 * can only be caused by:
2814 * - a new state was added
2815 * - somehow the element was asked to jump across an intermediate state
2817 g_warning ("Unhandled state change from %s to %s",
2818 gst_element_state_get_name (state),
2819 gst_element_state_get_name (next));
2826 GST_OBJECT_LOCK (element);
2827 result = GST_STATE_RETURN (element);
2828 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2829 "element is already in the %s state",
2830 gst_element_state_get_name (state));
2831 GST_OBJECT_UNLOCK (element);
2838 * gst_element_get_factory:
2839 * @element: a #GstElement to request the element factory of.
2841 * Retrieves the factory that was used to create this element.
2843 * Returns: (transfer none): the #GstElementFactory used for creating this
2844 * element. no refcounting is needed.
2847 gst_element_get_factory (GstElement * element)
2849 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2851 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2855 gst_element_dispose (GObject * object)
2857 GstElement *element = GST_ELEMENT_CAST (object);
2860 GstElementClass *oclass;
2863 oclass = GST_ELEMENT_GET_CLASS (element);
2865 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2867 if (GST_STATE (element) != GST_STATE_NULL)
2870 /* start by releasing all request pads, this might also remove some dynamic
2872 walk = element->pads;
2874 GstPad *pad = GST_PAD_CAST (walk->data);
2878 if (oclass->release_pad && GST_PAD_PAD_TEMPLATE (pad) &&
2879 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
2880 == GST_PAD_REQUEST) {
2881 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2882 "removing request pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2883 oclass->release_pad (element, pad);
2885 /* in case the release_pad function removed the next pad too */
2886 if (walk && g_list_position (element->pads, walk) == -1)
2887 walk = element->pads;
2890 /* remove the remaining pads */
2891 while (element->pads) {
2892 GstPad *pad = GST_PAD_CAST (element->pads->data);
2893 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2894 "removing pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2895 if (!gst_element_remove_pad (element, pad)) {
2896 /* only happens when someone unparented our pad.. */
2897 g_critical ("failed to remove pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2902 GST_OBJECT_LOCK (element);
2903 clock_p = &element->clock;
2904 bus_p = &element->bus;
2905 gst_object_replace ((GstObject **) clock_p, NULL);
2906 gst_object_replace ((GstObject **) bus_p, NULL);
2907 GST_OBJECT_UNLOCK (element);
2909 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2911 G_OBJECT_CLASS (parent_class)->dispose (object);
2920 is_locked = GST_ELEMENT_IS_LOCKED_STATE (element);
2922 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2924 "You need to explicitly set elements to the NULL state before\n"
2925 "dropping the final reference, to allow them to clean up.\n"
2926 "This problem may also be caused by a refcounting bug in the\n"
2927 "application or some element.\n",
2928 GST_OBJECT_NAME (element),
2929 gst_element_state_get_name (GST_STATE (element)),
2930 is_locked ? " (locked)" : "");
2936 gst_element_finalize (GObject * object)
2938 GstElement *element = GST_ELEMENT_CAST (object);
2940 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2942 g_cond_clear (&element->state_cond);
2943 g_rec_mutex_clear (&element->state_lock);
2945 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2947 G_OBJECT_CLASS (parent_class)->finalize (object);
2951 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2955 g_return_if_fail (GST_IS_ELEMENT (element));
2957 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2959 GST_OBJECT_LOCK (element);
2960 bus_p = &GST_ELEMENT_BUS (element);
2961 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
2962 GST_OBJECT_UNLOCK (element);
2966 * gst_element_set_bus:
2967 * @element: a #GstElement to set the bus of.
2968 * @bus: (transfer none): the #GstBus to set.
2970 * Sets the bus of the element. Increases the refcount on the bus.
2971 * For internal use only, unless you're testing elements.
2976 gst_element_set_bus (GstElement * element, GstBus * bus)
2978 GstElementClass *oclass;
2980 g_return_if_fail (GST_IS_ELEMENT (element));
2982 oclass = GST_ELEMENT_GET_CLASS (element);
2984 if (oclass->set_bus)
2985 oclass->set_bus (element, bus);
2989 * gst_element_get_bus:
2990 * @element: a #GstElement to get the bus of.
2992 * Returns the bus of the element. Note that only a #GstPipeline will provide a
2993 * bus for the application.
2995 * Returns: (transfer full): the element's #GstBus. unref after usage.
3000 gst_element_get_bus (GstElement * element)
3002 GstBus *result = NULL;
3004 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3006 GST_OBJECT_LOCK (element);
3007 if ((result = GST_ELEMENT_BUS (element)))
3008 gst_object_ref (result);
3009 GST_OBJECT_UNLOCK (element);
3011 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,