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);
136 static void gst_element_set_context_default (GstElement * element,
137 GstContext * context);
139 static gboolean gst_element_default_send_event (GstElement * element,
141 static gboolean gst_element_default_query (GstElement * element,
144 static GstPadTemplate
145 * gst_element_class_get_request_pad_template (GstElementClass *
146 element_class, const gchar * name);
148 static GstObjectClass *parent_class = NULL;
149 static guint gst_element_signals[LAST_SIGNAL] = { 0 };
151 /* this is used in gstelementfactory.c:gst_element_register() */
152 GQuark __gst_elementclass_factory = 0;
155 gst_element_get_type (void)
157 static volatile gsize gst_element_type = 0;
159 if (g_once_init_enter (&gst_element_type)) {
161 static const GTypeInfo element_info = {
162 sizeof (GstElementClass),
163 gst_element_base_class_init,
164 gst_element_base_class_finalize,
165 (GClassInitFunc) gst_element_class_init,
170 (GInstanceInitFunc) gst_element_init,
174 _type = g_type_register_static (GST_TYPE_OBJECT, "GstElement",
175 &element_info, G_TYPE_FLAG_ABSTRACT);
177 __gst_elementclass_factory =
178 g_quark_from_static_string ("GST_ELEMENTCLASS_FACTORY");
179 g_once_init_leave (&gst_element_type, _type);
181 return gst_element_type;
185 gst_element_class_init (GstElementClass * klass)
187 GObjectClass *gobject_class;
189 gobject_class = (GObjectClass *) klass;
191 parent_class = g_type_class_peek_parent (klass);
194 * GstElement::pad-added:
195 * @gstelement: the object which received the signal
196 * @new_pad: the pad that has been added
198 * a new #GstPad has been added to the element. Note that this signal will
199 * usually be emitted from the context of the streaming thread. Also keep in
200 * mind that if you add new elements to the pipeline in the signal handler
201 * you will need to set them to the desired target state with
202 * gst_element_set_state() or gst_element_sync_state_with_parent().
204 gst_element_signals[PAD_ADDED] =
205 g_signal_new ("pad-added", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
206 G_STRUCT_OFFSET (GstElementClass, pad_added), NULL, NULL,
207 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
209 * GstElement::pad-removed:
210 * @gstelement: the object which received the signal
211 * @old_pad: the pad that has been removed
213 * a #GstPad has been removed from the element
215 gst_element_signals[PAD_REMOVED] =
216 g_signal_new ("pad-removed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
217 G_STRUCT_OFFSET (GstElementClass, pad_removed), NULL, NULL,
218 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
220 * GstElement::no-more-pads:
221 * @gstelement: the object which received the signal
223 * This signals that the element will not generate more dynamic pads.
224 * Note that this signal will usually be emitted from the context of
225 * the streaming thread.
227 gst_element_signals[NO_MORE_PADS] =
228 g_signal_new ("no-more-pads", G_TYPE_FROM_CLASS (klass),
229 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstElementClass, no_more_pads), NULL,
230 NULL, g_cclosure_marshal_generic, G_TYPE_NONE, 0);
232 gobject_class->dispose = gst_element_dispose;
233 gobject_class->finalize = gst_element_finalize;
235 klass->change_state = GST_DEBUG_FUNCPTR (gst_element_change_state_func);
236 klass->set_state = GST_DEBUG_FUNCPTR (gst_element_set_state_func);
237 klass->get_state = GST_DEBUG_FUNCPTR (gst_element_get_state_func);
238 klass->set_clock = GST_DEBUG_FUNCPTR (gst_element_set_clock_func);
239 klass->set_bus = GST_DEBUG_FUNCPTR (gst_element_set_bus_func);
240 klass->query = GST_DEBUG_FUNCPTR (gst_element_default_query);
241 klass->send_event = GST_DEBUG_FUNCPTR (gst_element_default_send_event);
242 klass->numpadtemplates = 0;
243 klass->post_message = GST_DEBUG_FUNCPTR (gst_element_post_message_default);
244 klass->set_context = GST_DEBUG_FUNCPTR (gst_element_set_context_default);
246 klass->elementfactory = NULL;
250 gst_element_base_class_init (gpointer g_class)
252 GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
253 GList *node, *padtemplates;
255 /* Copy the element details here so elements can inherit the
256 * details from their base class and classes only need to set
257 * the details in class_init instead of base_init */
258 element_class->metadata =
259 element_class->metadata ? gst_structure_copy (element_class->metadata) :
260 gst_structure_new_empty ("metadata");
262 /* Copy the pad templates so elements inherit them
263 * from their base class but elements can add pad templates in class_init
264 * instead of base_init.
266 padtemplates = g_list_copy (element_class->padtemplates);
267 for (node = padtemplates; node != NULL; node = node->next) {
268 GstPadTemplate *tmpl = (GstPadTemplate *) node->data;
269 gst_object_ref (tmpl);
271 element_class->padtemplates = padtemplates;
273 /* set the factory, see gst_element_register() */
274 element_class->elementfactory =
275 g_type_get_qdata (G_TYPE_FROM_CLASS (element_class),
276 __gst_elementclass_factory);
277 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "type %s : factory %p",
278 G_OBJECT_CLASS_NAME (element_class), element_class->elementfactory);
282 gst_element_base_class_finalize (gpointer g_class)
284 GstElementClass *klass = GST_ELEMENT_CLASS (g_class);
286 g_list_foreach (klass->padtemplates, (GFunc) gst_object_unref, NULL);
287 g_list_free (klass->padtemplates);
289 gst_structure_free (klass->metadata);
293 gst_element_init (GstElement * element)
295 GST_STATE (element) = GST_STATE_NULL;
296 GST_STATE_TARGET (element) = GST_STATE_NULL;
297 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
298 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
299 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
301 g_rec_mutex_init (&element->state_lock);
302 g_cond_init (&element->state_cond);
306 * gst_element_release_request_pad:
307 * @element: a #GstElement to release the request pad of.
308 * @pad: the #GstPad to release.
310 * Makes the element free the previously requested pad as obtained
311 * with gst_element_request_pad().
313 * This does not unref the pad. If the pad was created by using
314 * gst_element_request_pad(), gst_element_release_request_pad() needs to be
315 * followed by gst_object_unref() to free the @pad.
320 gst_element_release_request_pad (GstElement * element, GstPad * pad)
322 GstElementClass *oclass;
324 g_return_if_fail (GST_IS_ELEMENT (element));
325 g_return_if_fail (GST_IS_PAD (pad));
326 g_return_if_fail (GST_PAD_PAD_TEMPLATE (pad) == NULL ||
327 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad)) ==
330 oclass = GST_ELEMENT_GET_CLASS (element);
332 /* if the element implements a custom release function we call that, else we
333 * simply remove the pad from the element */
334 if (oclass->release_pad)
335 oclass->release_pad (element, pad);
337 gst_element_remove_pad (element, pad);
341 * gst_element_provide_clock:
342 * @element: a #GstElement to query
344 * Get the clock provided by the given element.
345 * <note>An element is only required to provide a clock in the PAUSED
346 * state. Some elements can provide a clock in other states.</note>
348 * Returns: (transfer full) (nullable): the GstClock provided by the
349 * element or %NULL if no clock could be provided. Unref after usage.
354 gst_element_provide_clock (GstElement * element)
356 GstClock *result = NULL;
357 GstElementClass *oclass;
359 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
361 oclass = GST_ELEMENT_GET_CLASS (element);
363 if (oclass->provide_clock)
364 result = oclass->provide_clock (element);
370 gst_element_set_clock_func (GstElement * element, GstClock * clock)
374 GST_OBJECT_LOCK (element);
375 clock_p = &element->clock;
376 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
377 GST_OBJECT_UNLOCK (element);
383 * gst_element_set_clock:
384 * @element: a #GstElement to set the clock for.
385 * @clock: the #GstClock to set for the element.
387 * Sets the clock for the element. This function increases the
388 * refcount on the clock. Any previously set clock on the object
391 * Returns: %TRUE if the element accepted the clock. An element can refuse a
392 * clock when it, for example, is not able to slave its internal clock to the
393 * @clock or when it requires a specific clock to operate.
398 gst_element_set_clock (GstElement * element, GstClock * clock)
400 GstElementClass *oclass;
401 gboolean res = FALSE;
403 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
404 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
406 oclass = GST_ELEMENT_GET_CLASS (element);
408 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
410 if (oclass->set_clock)
411 res = oclass->set_clock (element, clock);
417 * gst_element_get_clock:
418 * @element: a #GstElement to get the clock of.
420 * Gets the currently configured clock of the element. This is the clock as was
421 * last set with gst_element_set_clock().
423 * Elements in a pipeline will only have their clock set when the
424 * pipeline is in the PLAYING state.
426 * Returns: (transfer full): the #GstClock of the element. unref after usage.
431 gst_element_get_clock (GstElement * element)
435 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
437 GST_OBJECT_LOCK (element);
438 if ((result = element->clock))
439 gst_object_ref (result);
440 GST_OBJECT_UNLOCK (element);
446 * gst_element_set_base_time:
447 * @element: a #GstElement.
448 * @time: the base time to set.
450 * Set the base time of an element. See gst_element_get_base_time().
455 gst_element_set_base_time (GstElement * element, GstClockTime time)
459 g_return_if_fail (GST_IS_ELEMENT (element));
461 GST_OBJECT_LOCK (element);
462 old = element->base_time;
463 element->base_time = time;
464 GST_OBJECT_UNLOCK (element);
466 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
467 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
468 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
472 * gst_element_get_base_time:
473 * @element: a #GstElement.
475 * Returns the base time of the element. The base time is the
476 * absolute time of the clock when this element was last put to
477 * PLAYING. Subtracting the base time from the clock time gives
478 * the running time of the element.
480 * Returns: the base time of the element.
485 gst_element_get_base_time (GstElement * element)
489 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
491 GST_OBJECT_LOCK (element);
492 result = element->base_time;
493 GST_OBJECT_UNLOCK (element);
499 * gst_element_set_start_time:
500 * @element: a #GstElement.
501 * @time: the base time to set.
503 * Set the start time of an element. The start time of the element is the
504 * running time of the element when it last went to the PAUSED state. In READY
505 * or after a flushing seek, it is set to 0.
507 * Toplevel elements like #GstPipeline will manage the start_time and
508 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
509 * on such a toplevel element will disable the distribution of the base_time to
510 * the children and can be useful if the application manages the base_time
511 * itself, for example if you want to synchronize capture from multiple
512 * pipelines, and you can also ensure that the pipelines have the same clock.
517 gst_element_set_start_time (GstElement * element, GstClockTime time)
521 g_return_if_fail (GST_IS_ELEMENT (element));
523 GST_OBJECT_LOCK (element);
524 old = GST_ELEMENT_START_TIME (element);
525 GST_ELEMENT_START_TIME (element) = time;
526 GST_OBJECT_UNLOCK (element);
528 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
529 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
530 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
534 * gst_element_get_start_time:
535 * @element: a #GstElement.
537 * Returns the start time of the element. The start time is the
538 * running time of the clock when this element was last put to PAUSED.
540 * Usually the start_time is managed by a toplevel element such as
545 * Returns: the start time of the element.
548 gst_element_get_start_time (GstElement * element)
552 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
554 GST_OBJECT_LOCK (element);
555 result = GST_ELEMENT_START_TIME (element);
556 GST_OBJECT_UNLOCK (element);
563 * gst_element_set_index:
564 * @element: a #GstElement.
565 * @index: (transfer none): a #GstIndex.
567 * Set @index on the element. The refcount of the index
568 * will be increased, any previously set index is unreffed.
573 gst_element_set_index (GstElement * element, GstIndex * index)
575 GstElementClass *oclass;
577 g_return_if_fail (GST_IS_ELEMENT (element));
578 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
580 oclass = GST_ELEMENT_GET_CLASS (element);
582 if (oclass->set_index)
583 oclass->set_index (element, index);
587 * gst_element_get_index:
588 * @element: a #GstElement.
590 * Gets the index from the element.
592 * Returns: (transfer full) (nullable): a #GstIndex or %NULL when no
593 * index was set on the element. unref after usage.
598 gst_element_get_index (GstElement * element)
600 GstElementClass *oclass;
601 GstIndex *result = NULL;
603 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
605 oclass = GST_ELEMENT_GET_CLASS (element);
607 if (oclass->get_index)
608 result = oclass->get_index (element);
615 * gst_element_add_pad:
616 * @element: a #GstElement to add the pad to.
617 * @pad: (transfer full): the #GstPad to add to the element.
619 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
620 * see gst_object_set_parent() for refcounting information.
622 * Pads are not automatically activated so elements should perform the needed
623 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
624 * state. See gst_pad_set_active() for more information about activating pads.
626 * The pad and the element should be unlocked when calling this function.
628 * This function will emit the #GstElement::pad-added signal on the element.
630 * Returns: %TRUE if the pad could be added. This function can fail when
631 * a pad with the same name already existed or the pad already had another
637 gst_element_add_pad (GstElement * element, GstPad * pad)
642 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
643 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
645 /* locking pad to look at the name */
646 GST_OBJECT_LOCK (pad);
647 pad_name = g_strdup (GST_PAD_NAME (pad));
648 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
649 GST_STR_NULL (pad_name));
650 flushing = GST_PAD_IS_FLUSHING (pad);
651 GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_NEED_PARENT);
652 GST_OBJECT_UNLOCK (pad);
654 /* then check to see if there's already a pad by that name here */
655 GST_OBJECT_LOCK (element);
656 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
659 /* try to set the pad's parent */
660 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
661 GST_OBJECT_CAST (element))))
664 /* check for flushing pads */
665 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
666 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
667 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
668 "use gst_pad_set_active(pad,TRUE) before adding it.",
669 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
671 GST_OBJECT_LOCK (pad);
672 GST_PAD_UNSET_FLUSHING (pad);
673 GST_OBJECT_UNLOCK (pad);
678 /* add it to the list */
679 switch (gst_pad_get_direction (pad)) {
681 element->srcpads = g_list_append (element->srcpads, pad);
682 element->numsrcpads++;
685 element->sinkpads = g_list_append (element->sinkpads, pad);
686 element->numsinkpads++;
691 element->pads = g_list_append (element->pads, pad);
693 element->pads_cookie++;
694 GST_OBJECT_UNLOCK (element);
696 /* emit the PAD_ADDED signal */
697 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
704 g_critical ("Padname %s is not unique in element %s, not adding",
705 pad_name, GST_ELEMENT_NAME (element));
706 GST_OBJECT_UNLOCK (element);
713 ("Pad %s already has parent when trying to add to element %s",
714 pad_name, GST_ELEMENT_NAME (element));
715 GST_OBJECT_UNLOCK (element);
721 GST_OBJECT_LOCK (pad);
723 ("Trying to add pad %s to element %s, but it has no direction",
724 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
725 GST_OBJECT_UNLOCK (pad);
726 GST_OBJECT_UNLOCK (element);
732 * gst_element_remove_pad:
733 * @element: a #GstElement to remove pad from.
734 * @pad: (transfer full): the #GstPad to remove from the element.
736 * Removes @pad from @element. @pad will be destroyed if it has not been
737 * referenced elsewhere using gst_object_unparent().
739 * This function is used by plugin developers and should not be used
740 * by applications. Pads that were dynamically requested from elements
741 * with gst_element_request_pad() should be released with the
742 * gst_element_release_request_pad() function instead.
744 * Pads are not automatically deactivated so elements should perform the needed
745 * steps to deactivate the pad in case this pad is removed in the PAUSED or
746 * PLAYING state. See gst_pad_set_active() for more information about
749 * The pad and the element should be unlocked when calling this function.
751 * This function will emit the #GstElement::pad-removed signal on the element.
753 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
754 * pad does not belong to the provided element.
759 gst_element_remove_pad (GstElement * element, GstPad * pad)
763 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
764 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
766 /* locking pad to look at the name and parent */
767 GST_OBJECT_LOCK (pad);
768 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
769 GST_STR_NULL (GST_PAD_NAME (pad)));
771 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
773 GST_OBJECT_UNLOCK (pad);
776 if ((peer = gst_pad_get_peer (pad))) {
777 /* window for MT unsafeness, someone else could unlink here
778 * and then we call unlink with wrong pads. The unlink
779 * function would catch this and safely return failed. */
780 if (GST_PAD_IS_SRC (pad))
781 gst_pad_unlink (pad, peer);
783 gst_pad_unlink (peer, pad);
785 gst_object_unref (peer);
788 GST_OBJECT_LOCK (element);
789 /* remove it from the list */
790 switch (gst_pad_get_direction (pad)) {
792 element->srcpads = g_list_remove (element->srcpads, pad);
793 element->numsrcpads--;
796 element->sinkpads = g_list_remove (element->sinkpads, pad);
797 element->numsinkpads--;
800 g_critical ("Removing pad without direction???");
803 element->pads = g_list_remove (element->pads, pad);
805 element->pads_cookie++;
806 GST_OBJECT_UNLOCK (element);
808 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
809 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
811 gst_object_unparent (GST_OBJECT_CAST (pad));
818 /* locking order is element > pad */
819 GST_OBJECT_UNLOCK (pad);
821 GST_OBJECT_LOCK (element);
822 GST_OBJECT_LOCK (pad);
823 g_critical ("Padname %s:%s does not belong to element %s when removing",
824 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
825 GST_OBJECT_UNLOCK (pad);
826 GST_OBJECT_UNLOCK (element);
832 * gst_element_no_more_pads:
833 * @element: a #GstElement
835 * Use this function to signal that the element does not expect any more pads
836 * to show up in the current pipeline. This function should be called whenever
837 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
838 * pad templates use this in combination with autopluggers to figure out that
839 * the element is done initializing its pads.
841 * This function emits the #GstElement::no-more-pads signal.
846 gst_element_no_more_pads (GstElement * element)
848 g_return_if_fail (GST_IS_ELEMENT (element));
850 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
854 pad_compare_name (GstPad * pad1, const gchar * name)
858 GST_OBJECT_LOCK (pad1);
859 result = strcmp (GST_PAD_NAME (pad1), name);
860 GST_OBJECT_UNLOCK (pad1);
866 * gst_element_get_static_pad:
867 * @element: a #GstElement to find a static pad of.
868 * @name: the name of the static #GstPad to retrieve.
870 * Retrieves a pad from @element by name. This version only retrieves
871 * already-existing (i.e. 'static') pads.
873 * Returns: (transfer full) (nullable): the requested #GstPad if
874 * found, otherwise %NULL. unref after usage.
879 gst_element_get_static_pad (GstElement * element, const gchar * name)
882 GstPad *result = NULL;
884 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
885 g_return_val_if_fail (name != NULL, NULL);
887 GST_OBJECT_LOCK (element);
889 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
891 result = GST_PAD_CAST (find->data);
892 gst_object_ref (result);
895 if (result == NULL) {
896 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
897 name, GST_ELEMENT_NAME (element));
899 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
900 GST_ELEMENT_NAME (element), name);
902 GST_OBJECT_UNLOCK (element);
908 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
909 const gchar * name, const GstCaps * caps)
911 GstPad *newpad = NULL;
912 GstElementClass *oclass;
914 oclass = GST_ELEMENT_GET_CLASS (element);
916 #ifndef G_DISABLE_CHECKS
917 /* Some sanity checking here */
921 /* Is this the template name? */
922 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
923 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
925 const gchar *str, *data;
928 /* Otherwise check if it's a valid name for the name template */
929 str = strchr (templ->name_template, '%');
930 g_return_val_if_fail (str != NULL, NULL);
931 g_return_val_if_fail (strncmp (templ->name_template, name,
932 str - templ->name_template) == 0, NULL);
933 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
935 data = name + (str - templ->name_template);
937 /* Can either be %s or %d or %u, do sanity checking for %d */
938 if (*(str + 1) == 'd') {
942 tmp = g_ascii_strtoll (data, &endptr, 10);
943 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
944 && *endptr == '\0', NULL);
945 } else if (*(str + 1) == 'u') {
949 tmp = g_ascii_strtoull (data, &endptr, 10);
950 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
954 pad = gst_element_get_static_pad (element, name);
956 gst_object_unref (pad);
957 /* FIXME 2.0: Change this to g_return_val_if_fail() */
958 g_critical ("Element %s already has a pad named %s, the behaviour of "
959 " gst_element_get_request_pad() for existing pads is undefined!",
960 GST_ELEMENT_NAME (element), name);
965 if (oclass->request_new_pad)
966 newpad = (oclass->request_new_pad) (element, templ, name, caps);
969 gst_object_ref (newpad);
975 * gst_element_get_request_pad:
976 * @element: a #GstElement to find a request pad of.
977 * @name: the name of the request #GstPad to retrieve.
979 * Retrieves a pad from the element by name (e.g. "src_\%d"). This version only
980 * retrieves request pads. The pad should be released with
981 * gst_element_release_request_pad().
983 * This method is slower than manually getting the pad template and calling
984 * gst_element_request_pad() if the pads should have a specific name (e.g.
985 * @name is "src_1" instead of "src_\%u").
987 * Returns: (transfer full) (nullable): requested #GstPad if found,
988 * otherwise %NULL. Release after usage.
991 gst_element_get_request_pad (GstElement * element, const gchar * name)
993 GstPadTemplate *templ = NULL;
995 const gchar *req_name = NULL;
996 gboolean templ_found = FALSE;
999 gchar *str, *endptr = NULL;
1000 GstElementClass *class;
1002 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1003 g_return_val_if_fail (name != NULL, NULL);
1005 class = GST_ELEMENT_GET_CLASS (element);
1007 /* if the name contains a %, we assume it's the complete template name. Get
1008 * the template and try to get a pad */
1009 if (strstr (name, "%")) {
1010 templ = gst_element_class_get_request_pad_template (class, name);
1015 /* there is no % in the name, try to find a matching template */
1016 list = class->padtemplates;
1017 while (!templ_found && list) {
1018 templ = (GstPadTemplate *) list->data;
1019 if (templ->presence == GST_PAD_REQUEST) {
1020 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1021 templ->name_template);
1022 /* see if we find an exact match */
1023 if (strcmp (name, templ->name_template) == 0) {
1028 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1029 and %d and %u, occurring at the end of the name_template, are the only
1031 else if ((str = strchr (templ->name_template, '%'))
1032 && strncmp (templ->name_template, name,
1033 str - templ->name_template) == 0
1034 && strlen (name) > str - templ->name_template) {
1035 data = name + (str - templ->name_template);
1036 if (*(str + 1) == 'd') {
1040 tmp = strtol (data, &endptr, 10);
1041 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1047 } else if (*(str + 1) == 'u') {
1051 tmp = strtoul (data, &endptr, 10);
1052 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1072 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1078 * gst_element_request_pad: (virtual request_new_pad)
1079 * @element: a #GstElement to find a request pad of.
1080 * @templ: a #GstPadTemplate of which we want a pad of.
1081 * @name: (transfer none) (allow-none): the name of the request #GstPad
1082 * to retrieve. Can be %NULL.
1083 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1084 * request. Can be %NULL.
1086 * Retrieves a request pad from the element according to the provided template.
1087 * Pad templates can be looked up using
1088 * gst_element_factory_get_static_pad_templates().
1090 * The pad should be released with gst_element_release_request_pad().
1092 * Returns: (transfer full) (nullable): requested #GstPad if found,
1093 * otherwise %NULL. Release after usage.
1096 gst_element_request_pad (GstElement * element,
1097 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1099 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1100 g_return_val_if_fail (templ != NULL, NULL);
1101 g_return_val_if_fail (templ->presence == GST_PAD_REQUEST, NULL);
1103 return _gst_element_request_pad (element, templ, name, caps);
1106 static GstIterator *
1107 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1109 GstIterator *result;
1111 GST_OBJECT_LOCK (element);
1112 result = gst_iterator_new_list (GST_TYPE_PAD,
1113 GST_OBJECT_GET_LOCK (element),
1114 &element->pads_cookie, padlist, (GObject *) element, NULL);
1115 GST_OBJECT_UNLOCK (element);
1121 * gst_element_iterate_pads:
1122 * @element: a #GstElement to iterate pads of.
1124 * Retrieves an iterator of @element's pads. The iterator should
1125 * be freed after usage. Also more specialized iterators exists such as
1126 * gst_element_iterate_src_pads() or gst_element_iterate_sink_pads().
1128 * The order of pads returned by the iterator will be the order in which
1129 * the pads were added to the element.
1131 * Returns: (transfer full): the #GstIterator of #GstPad.
1136 gst_element_iterate_pads (GstElement * element)
1138 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1140 return gst_element_iterate_pad_list (element, &element->pads);
1144 * gst_element_iterate_src_pads:
1145 * @element: a #GstElement.
1147 * Retrieves an iterator of @element's source pads.
1149 * The order of pads returned by the iterator will be the order in which
1150 * the pads were added to the element.
1152 * Returns: (transfer full): the #GstIterator of #GstPad.
1157 gst_element_iterate_src_pads (GstElement * element)
1159 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1161 return gst_element_iterate_pad_list (element, &element->srcpads);
1165 * gst_element_iterate_sink_pads:
1166 * @element: a #GstElement.
1168 * Retrieves an iterator of @element's sink pads.
1170 * The order of pads returned by the iterator will be the order in which
1171 * the pads were added to the element.
1173 * Returns: (transfer full): the #GstIterator of #GstPad.
1178 gst_element_iterate_sink_pads (GstElement * element)
1180 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1182 return gst_element_iterate_pad_list (element, &element->sinkpads);
1186 * gst_element_class_add_pad_template:
1187 * @klass: the #GstElementClass to add the pad template to.
1188 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1190 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1191 * functions of classes. If a pad template with the same name as an already
1192 * existing one is added the old one is replaced by the new one.
1196 gst_element_class_add_pad_template (GstElementClass * klass,
1197 GstPadTemplate * templ)
1199 GList *template_list = klass->padtemplates;
1201 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1202 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1204 /* If we already have a pad template with the same name replace the
1206 while (template_list) {
1207 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1209 /* Found pad with the same name, replace and return */
1210 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1211 gst_object_unref (padtempl);
1212 template_list->data = templ;
1215 template_list = g_list_next (template_list);
1218 /* Take ownership of the floating ref */
1219 gst_object_ref_sink (templ);
1221 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1222 klass->numpadtemplates++;
1226 * gst_element_class_add_metadata:
1227 * @klass: class to set metadata for
1228 * @key: the key to set
1229 * @value: the value to set
1231 * Set @key with @value as metadata in @klass.
1234 gst_element_class_add_metadata (GstElementClass * klass,
1235 const gchar * key, const gchar * value)
1237 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1238 g_return_if_fail (key != NULL);
1239 g_return_if_fail (value != NULL);
1241 gst_structure_set ((GstStructure *) klass->metadata,
1242 key, G_TYPE_STRING, value, NULL);
1246 * gst_element_class_add_static_metadata:
1247 * @klass: class to set metadata for
1248 * @key: the key to set
1249 * @value: the value to set
1251 * Set @key with @value as metadata in @klass.
1253 * Same as gst_element_class_add_metadata(), but @value must be a static string
1254 * or an inlined string, as it will not be copied. (GStreamer plugins will
1255 * be made resident once loaded, so this function can be used even from
1256 * dynamically loaded plugins.)
1259 gst_element_class_add_static_metadata (GstElementClass * klass,
1260 const gchar * key, const gchar * value)
1262 GValue val = G_VALUE_INIT;
1264 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1265 g_return_if_fail (key != NULL);
1266 g_return_if_fail (value != NULL);
1268 g_value_init (&val, G_TYPE_STRING);
1269 g_value_set_static_string (&val, value);
1270 gst_structure_take_value ((GstStructure *) klass->metadata, key, &val);
1274 * gst_element_class_set_metadata:
1275 * @klass: class to set metadata for
1276 * @longname: The long English name of the element. E.g. "File Sink"
1277 * @classification: String describing the type of element, as an unordered list
1278 * separated with slashes ('/'). See draft-klass.txt of the design docs
1279 * for more details and common types. E.g: "Sink/File"
1280 * @description: Sentence describing the purpose of the element.
1281 * E.g: "Write stream to a file"
1282 * @author: Name and contact details of the author(s). Use \n to separate
1283 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1285 * Sets the detailed information for a #GstElementClass.
1286 * <note>This function is for use in _class_init functions only.</note>
1289 gst_element_class_set_metadata (GstElementClass * klass,
1290 const gchar * longname, const gchar * classification,
1291 const gchar * description, const gchar * author)
1293 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1294 g_return_if_fail (longname != NULL && *longname != '\0');
1295 g_return_if_fail (classification != NULL && *classification != '\0');
1296 g_return_if_fail (description != NULL && *description != '\0');
1297 g_return_if_fail (author != NULL && *author != '\0');
1299 gst_structure_id_set ((GstStructure *) klass->metadata,
1300 GST_QUARK (ELEMENT_METADATA_LONGNAME), G_TYPE_STRING, longname,
1301 GST_QUARK (ELEMENT_METADATA_KLASS), G_TYPE_STRING, classification,
1302 GST_QUARK (ELEMENT_METADATA_DESCRIPTION), G_TYPE_STRING, description,
1303 GST_QUARK (ELEMENT_METADATA_AUTHOR), G_TYPE_STRING, author, NULL);
1307 * gst_element_class_set_static_metadata:
1308 * @klass: class to set metadata for
1309 * @longname: The long English name of the element. E.g. "File Sink"
1310 * @classification: String describing the type of element, as an unordered list
1311 * separated with slashes ('/'). See draft-klass.txt of the design docs
1312 * for more details and common types. E.g: "Sink/File"
1313 * @description: Sentence describing the purpose of the element.
1314 * E.g: "Write stream to a file"
1315 * @author: Name and contact details of the author(s). Use \n to separate
1316 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1318 * Sets the detailed information for a #GstElementClass.
1319 * <note>This function is for use in _class_init functions only.</note>
1321 * Same as gst_element_class_set_metadata(), but @longname, @classification,
1322 * @description, and @author must be static strings or inlined strings, as
1323 * they will not be copied. (GStreamer plugins will be made resident once
1324 * loaded, so this function can be used even from dynamically loaded plugins.)
1327 gst_element_class_set_static_metadata (GstElementClass * klass,
1328 const gchar * longname, const gchar * classification,
1329 const gchar * description, const gchar * author)
1331 GstStructure *s = (GstStructure *) klass->metadata;
1332 GValue val = G_VALUE_INIT;
1334 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1335 g_return_if_fail (longname != NULL && *longname != '\0');
1336 g_return_if_fail (classification != NULL && *classification != '\0');
1337 g_return_if_fail (description != NULL && *description != '\0');
1338 g_return_if_fail (author != NULL && *author != '\0');
1340 g_value_init (&val, G_TYPE_STRING);
1342 g_value_set_static_string (&val, longname);
1343 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_LONGNAME), &val);
1345 g_value_set_static_string (&val, classification);
1346 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_KLASS), &val);
1348 g_value_set_static_string (&val, description);
1349 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_DESCRIPTION),
1352 g_value_set_static_string (&val, author);
1353 gst_structure_id_take_value (s, GST_QUARK (ELEMENT_METADATA_AUTHOR), &val);
1357 * gst_element_class_get_metadata:
1358 * @klass: class to get metadata for
1359 * @key: the key to get
1361 * Get metadata with @key in @klass.
1363 * Returns: the metadata for @key.
1366 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1368 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1369 g_return_val_if_fail (key != NULL, NULL);
1371 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1375 * gst_element_class_get_pad_template_list:
1376 * @element_class: a #GstElementClass to get pad templates of.
1378 * Retrieves a list of the pad templates associated with @element_class. The
1379 * list must not be modified by the calling code.
1380 * <note>If you use this function in the #GInstanceInitFunc of an object class
1381 * that has subclasses, make sure to pass the g_class parameter of the
1382 * #GInstanceInitFunc here.</note>
1384 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1388 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1390 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1392 return element_class->padtemplates;
1396 * gst_element_class_get_pad_template:
1397 * @element_class: a #GstElementClass to get the pad template of.
1398 * @name: the name of the #GstPadTemplate to get.
1400 * Retrieves a padtemplate from @element_class with the given name.
1401 * <note>If you use this function in the #GInstanceInitFunc of an object class
1402 * that has subclasses, make sure to pass the g_class parameter of the
1403 * #GInstanceInitFunc here.</note>
1405 * Returns: (transfer none) (nullable): the #GstPadTemplate with the
1406 * given name, or %NULL if none was found. No unreferencing is
1410 gst_element_class_get_pad_template (GstElementClass *
1411 element_class, const gchar * name)
1415 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1416 g_return_val_if_fail (name != NULL, NULL);
1418 padlist = element_class->padtemplates;
1421 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1423 if (strcmp (padtempl->name_template, name) == 0)
1426 padlist = g_list_next (padlist);
1432 static GstPadTemplate *
1433 gst_element_class_get_request_pad_template (GstElementClass *
1434 element_class, const gchar * name)
1436 GstPadTemplate *tmpl;
1438 tmpl = gst_element_class_get_pad_template (element_class, name);
1439 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1445 /* get a random pad on element of the given direction.
1446 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1449 gst_element_get_random_pad (GstElement * element,
1450 gboolean need_linked, GstPadDirection dir)
1452 GstPad *result = NULL;
1455 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1459 GST_OBJECT_LOCK (element);
1460 pads = element->srcpads;
1463 GST_OBJECT_LOCK (element);
1464 pads = element->sinkpads;
1467 goto wrong_direction;
1469 for (; pads; pads = g_list_next (pads)) {
1470 GstPad *pad = GST_PAD_CAST (pads->data);
1472 GST_OBJECT_LOCK (pad);
1473 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1474 GST_DEBUG_PAD_NAME (pad));
1476 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1477 /* if we require a linked pad, and it is not linked, continue the
1479 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1480 GST_DEBUG_PAD_NAME (pad));
1481 GST_OBJECT_UNLOCK (pad);
1484 /* found a pad, stop search */
1485 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1486 GST_DEBUG_PAD_NAME (pad));
1487 GST_OBJECT_UNLOCK (pad);
1493 gst_object_ref (result);
1495 GST_OBJECT_UNLOCK (element);
1499 /* ERROR handling */
1502 g_warning ("unknown pad direction %d", dir);
1508 gst_element_default_send_event (GstElement * element, GstEvent * event)
1510 gboolean result = FALSE;
1513 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1514 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK) :
1515 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC);
1518 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1519 "pushing %s event to random %s pad %s:%s",
1520 GST_EVENT_TYPE_NAME (event),
1521 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1522 GST_DEBUG_PAD_NAME (pad));
1524 result = gst_pad_send_event (pad, event);
1525 gst_object_unref (pad);
1527 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1528 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1529 gst_event_unref (event);
1535 * gst_element_send_event:
1536 * @element: a #GstElement to send the event to.
1537 * @event: (transfer full): the #GstEvent to send to the element.
1539 * Sends an event to an element. If the element doesn't implement an
1540 * event handler, the event will be pushed on a random linked sink pad for
1541 * downstream events or a random linked source pad for upstream events.
1543 * This function takes ownership of the provided event so you should
1544 * gst_event_ref() it if you want to reuse the event after this call.
1548 * Returns: %TRUE if the event was handled. Events that trigger a preroll (such
1549 * as flushing seeks and steps) will emit %GST_MESSAGE_ASYNC_DONE.
1552 gst_element_send_event (GstElement * element, GstEvent * event)
1554 GstElementClass *oclass;
1555 gboolean result = FALSE;
1557 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1558 g_return_val_if_fail (event != NULL, FALSE);
1560 oclass = GST_ELEMENT_GET_CLASS (element);
1562 GST_STATE_LOCK (element);
1563 if (oclass->send_event) {
1564 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1565 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1566 result = oclass->send_event (element, event);
1568 GST_STATE_UNLOCK (element);
1575 * @element: a #GstElement to send the event to.
1576 * @rate: The new playback rate
1577 * @format: The format of the seek values
1578 * @flags: The optional seek flags.
1579 * @start_type: The type and flags for the new start position
1580 * @start: The value of the new start position
1581 * @stop_type: The type and flags for the new stop position
1582 * @stop: The value of the new stop position
1584 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1585 * the parameters. The seek event is sent to the element using
1586 * gst_element_send_event().
1590 * Returns: %TRUE if the event was handled. Flushing seeks will trigger a
1591 * preroll, which will emit %GST_MESSAGE_ASYNC_DONE.
1594 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1595 GstSeekFlags flags, GstSeekType start_type, gint64 start,
1596 GstSeekType stop_type, gint64 stop)
1601 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1604 gst_event_new_seek (rate, format, flags, start_type, start, stop_type,
1606 result = gst_element_send_event (element, event);
1612 gst_element_default_query (GstElement * element, GstQuery * query)
1614 gboolean result = FALSE;
1617 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1619 result = gst_pad_query (pad, query);
1621 gst_object_unref (pad);
1623 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1625 GstPad *peer = gst_pad_get_peer (pad);
1628 result = gst_pad_query (peer, query);
1630 gst_object_unref (peer);
1632 gst_object_unref (pad);
1639 * gst_element_query:
1640 * @element: a #GstElement to perform the query on.
1641 * @query: (transfer none): the #GstQuery.
1643 * Performs a query on the given element.
1645 * For elements that don't implement a query handler, this function
1646 * forwards the query to a random srcpad or to the peer of a
1647 * random linked sinkpad of this element.
1649 * Please note that some queries might need a running pipeline to work.
1651 * Returns: %TRUE if the query could be performed.
1656 gst_element_query (GstElement * element, GstQuery * query)
1658 GstElementClass *klass;
1660 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1661 g_return_val_if_fail (query != NULL, FALSE);
1663 klass = GST_ELEMENT_GET_CLASS (element);
1665 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1666 GST_ELEMENT_NAME (element));
1667 return klass->query (element, query);
1674 gst_element_post_message_default (GstElement * element, GstMessage * message)
1677 gboolean result = FALSE;
1679 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1680 g_return_val_if_fail (message != NULL, FALSE);
1682 GST_OBJECT_LOCK (element);
1685 if (G_UNLIKELY (bus == NULL))
1688 gst_object_ref (bus);
1689 GST_OBJECT_UNLOCK (element);
1691 /* we release the element lock when posting the message so that any
1692 * (synchronous) message handlers can operate on the element */
1693 result = gst_bus_post (bus, message);
1694 gst_object_unref (bus);
1701 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1702 "not posting message %p: no bus", message);
1703 GST_OBJECT_UNLOCK (element);
1704 gst_message_unref (message);
1710 * gst_element_post_message:
1711 * @element: a #GstElement posting the message
1712 * @message: (transfer full): a #GstMessage to post
1714 * Post a message on the element's #GstBus. This function takes ownership of the
1715 * message; if you want to access the message after this call, you should add an
1716 * additional reference before calling.
1718 * Returns: %TRUE if the message was successfully posted. The function returns
1719 * %FALSE if the element did not have a bus.
1724 gst_element_post_message (GstElement * element, GstMessage * message)
1726 GstElementClass *klass;
1728 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1729 g_return_val_if_fail (message != NULL, FALSE);
1731 klass = GST_ELEMENT_GET_CLASS (element);
1732 if (klass->post_message)
1733 return klass->post_message (element, message);
1739 * _gst_element_error_printf:
1740 * @format: (allow-none): the printf-like format to use, or %NULL
1742 * This function is only used internally by the gst_element_error() macro.
1744 * Returns: (transfer full) (nullable): a newly allocated string, or
1745 * %NULL if the format was %NULL or ""
1750 _gst_element_error_printf (const gchar * format, ...)
1761 va_start (args, format);
1763 len = __gst_vasprintf (&buffer, format, args);
1774 * gst_element_message_full:
1775 * @element: a #GstElement to send message from
1776 * @type: the #GstMessageType
1777 * @domain: the GStreamer GError domain this message belongs to
1778 * @code: the GError code belonging to the domain
1779 * @text: (allow-none) (transfer full): an allocated text string to be used
1780 * as a replacement for the default message connected to code,
1782 * @debug: (allow-none) (transfer full): an allocated debug message to be
1783 * used as a replacement for the default debugging information,
1785 * @file: the source code file where the error was generated
1786 * @function: the source code function where the error was generated
1787 * @line: the source code line where the error was generated
1789 * Post an error, warning or info message on the bus from inside an element.
1791 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1792 * #GST_MESSAGE_INFO.
1796 void gst_element_message_full
1797 (GstElement * element, GstMessageType type,
1798 GQuark domain, gint code, gchar * text,
1799 gchar * debug, const gchar * file, const gchar * function, gint line)
1801 GError *gerror = NULL;
1805 gboolean has_debug = TRUE;
1806 GstMessage *message = NULL;
1809 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1810 g_return_if_fail (GST_IS_ELEMENT (element));
1811 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1812 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1814 /* check if we send the given text or the default error text */
1815 if ((text == NULL) || (text[0] == 0)) {
1816 /* text could have come from g_strdup_printf (""); */
1818 sent_text = gst_error_get_message (domain, code);
1822 /* construct a sent_debug with extra information from source */
1823 if ((debug == NULL) || (debug[0] == 0)) {
1824 /* debug could have come from g_strdup_printf (""); */
1828 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1830 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1831 file, line, function, name, debug);
1833 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1834 file, line, function, name);
1838 /* create gerror and post message */
1839 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1841 gerror = g_error_new_literal (domain, code, sent_text);
1844 case GST_MESSAGE_ERROR:
1846 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1848 case GST_MESSAGE_WARNING:
1849 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1852 case GST_MESSAGE_INFO:
1853 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1857 g_assert_not_reached ();
1860 gst_element_post_message (element, message);
1862 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1863 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1866 g_error_free (gerror);
1867 g_free (sent_debug);
1872 * gst_element_is_locked_state:
1873 * @element: a #GstElement.
1875 * Checks if the state of an element is locked.
1876 * If the state of an element is locked, state changes of the parent don't
1877 * affect the element.
1878 * This way you can leave currently unused elements inside bins. Just lock their
1879 * state before changing the state from #GST_STATE_NULL.
1883 * Returns: %TRUE, if the element's state is locked.
1886 gst_element_is_locked_state (GstElement * element)
1890 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1892 GST_OBJECT_LOCK (element);
1893 result = GST_ELEMENT_IS_LOCKED_STATE (element);
1894 GST_OBJECT_UNLOCK (element);
1900 * gst_element_set_locked_state:
1901 * @element: a #GstElement
1902 * @locked_state: %TRUE to lock the element's state
1904 * Locks the state of an element, so state changes of the parent don't affect
1905 * this element anymore.
1909 * Returns: %TRUE if the state was changed, %FALSE if bad parameters were given
1910 * or the elements state-locking needed no change.
1913 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1917 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1919 GST_OBJECT_LOCK (element);
1920 old = GST_ELEMENT_IS_LOCKED_STATE (element);
1922 if (G_UNLIKELY (old == locked_state))
1926 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1927 GST_ELEMENT_NAME (element));
1928 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1930 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1931 GST_ELEMENT_NAME (element));
1932 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1934 GST_OBJECT_UNLOCK (element);
1940 GST_CAT_DEBUG (GST_CAT_STATES,
1941 "elements %s was already in locked state %d",
1942 GST_ELEMENT_NAME (element), old);
1943 GST_OBJECT_UNLOCK (element);
1950 * gst_element_sync_state_with_parent:
1951 * @element: a #GstElement.
1953 * Tries to change the state of the element to the same as its parent.
1954 * If this function returns %FALSE, the state of element is undefined.
1956 * Returns: %TRUE, if the element's state could be synced to the parent's state.
1961 gst_element_sync_state_with_parent (GstElement * element)
1965 GstStateChangeReturn ret;
1967 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1969 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1970 GstState parent_current, parent_pending;
1972 GST_OBJECT_LOCK (parent);
1973 parent_current = GST_STATE (parent);
1974 parent_pending = GST_STATE_PENDING (parent);
1975 GST_OBJECT_UNLOCK (parent);
1977 /* set to pending if there is one, else we set it to the current state of
1979 if (parent_pending != GST_STATE_VOID_PENDING)
1980 target = parent_pending;
1982 target = parent_current;
1984 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1985 "syncing state (%s) to parent %s %s (%s, %s)",
1986 gst_element_state_get_name (GST_STATE (element)),
1987 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1988 gst_element_state_get_name (parent_current),
1989 gst_element_state_get_name (parent_pending));
1991 ret = gst_element_set_state (element, target);
1992 if (ret == GST_STATE_CHANGE_FAILURE)
1995 gst_object_unref (parent);
1999 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
2006 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2007 "syncing state failed (%s)",
2008 gst_element_state_change_return_get_name (ret));
2009 gst_object_unref (parent);
2015 static GstStateChangeReturn
2016 gst_element_get_state_func (GstElement * element,
2017 GstState * state, GstState * pending, GstClockTime timeout)
2019 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2020 GstState old_pending;
2022 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2023 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2025 GST_OBJECT_LOCK (element);
2026 ret = GST_STATE_RETURN (element);
2027 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2028 gst_element_state_change_return_get_name (ret));
2030 /* we got an error, report immediately */
2031 if (ret == GST_STATE_CHANGE_FAILURE)
2034 /* we got no_preroll, report immediately */
2035 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2038 /* no need to wait async if we are not async */
2039 if (ret != GST_STATE_CHANGE_ASYNC)
2042 old_pending = GST_STATE_PENDING (element);
2043 if (old_pending != GST_STATE_VOID_PENDING) {
2047 /* get cookie to detect state changes during waiting */
2048 cookie = element->state_cookie;
2050 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2051 "waiting for element to commit state");
2053 /* we have a pending state change, wait for it to complete */
2054 if (timeout != GST_CLOCK_TIME_NONE) {
2056 /* make timeout absolute */
2057 end_time = g_get_monotonic_time () + (timeout / 1000);
2058 signaled = GST_STATE_WAIT_UNTIL (element, end_time);
2060 GST_STATE_WAIT (element);
2065 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2066 /* timeout triggered */
2067 ret = GST_STATE_CHANGE_ASYNC;
2069 if (cookie != element->state_cookie)
2072 /* could be success or failure */
2073 if (old_pending == GST_STATE (element)) {
2074 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2075 ret = GST_STATE_CHANGE_SUCCESS;
2077 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2078 ret = GST_STATE_CHANGE_FAILURE;
2081 /* if nothing is pending anymore we can return SUCCESS */
2082 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2083 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2084 ret = GST_STATE_CHANGE_SUCCESS;
2090 *state = GST_STATE (element);
2092 *pending = GST_STATE_PENDING (element);
2094 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2095 "state current: %s, pending: %s, result: %s",
2096 gst_element_state_get_name (GST_STATE (element)),
2097 gst_element_state_get_name (GST_STATE_PENDING (element)),
2098 gst_element_state_change_return_get_name (ret));
2099 GST_OBJECT_UNLOCK (element);
2106 *state = GST_STATE_VOID_PENDING;
2108 *pending = GST_STATE_VOID_PENDING;
2110 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2112 GST_OBJECT_UNLOCK (element);
2114 return GST_STATE_CHANGE_FAILURE;
2119 * gst_element_get_state:
2120 * @element: a #GstElement to get the state of.
2121 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2123 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2124 * state. Can be %NULL.
2125 * @timeout: a #GstClockTime to specify the timeout for an async
2126 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2128 * Gets the state of the element.
2130 * For elements that performed an ASYNC state change, as reported by
2131 * gst_element_set_state(), this function will block up to the
2132 * specified timeout value for the state change to complete.
2133 * If the element completes the state change or goes into
2134 * an error, this function returns immediately with a return value of
2135 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2137 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2138 * returns the current and pending state immediately.
2140 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2141 * successfully changed its state but is not able to provide data yet.
2142 * This mostly happens for live sources that only produce data in
2143 * %GST_STATE_PLAYING. While the state change return is equivalent to
2144 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2145 * some sink elements might not be able to complete their state change because
2146 * an element is not producing data to complete the preroll. When setting the
2147 * element to playing, the preroll will complete and playback will start.
2149 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2150 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2151 * element is still performing a state change or
2152 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2156 GstStateChangeReturn
2157 gst_element_get_state (GstElement * element,
2158 GstState * state, GstState * pending, GstClockTime timeout)
2160 GstElementClass *oclass;
2161 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2163 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2165 oclass = GST_ELEMENT_GET_CLASS (element);
2167 if (oclass->get_state)
2168 result = (oclass->get_state) (element, state, pending, timeout);
2174 * gst_element_abort_state:
2175 * @element: a #GstElement to abort the state of.
2177 * Abort the state change of the element. This function is used
2178 * by elements that do asynchronous state changes and find out
2179 * something is wrong.
2181 * This function should be called with the STATE_LOCK held.
2186 gst_element_abort_state (GstElement * element)
2190 #ifndef GST_DISABLE_GST_DEBUG
2194 g_return_if_fail (GST_IS_ELEMENT (element));
2196 GST_OBJECT_LOCK (element);
2197 pending = GST_STATE_PENDING (element);
2199 if (pending == GST_STATE_VOID_PENDING ||
2200 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2201 goto nothing_aborted;
2203 #ifndef GST_DISABLE_GST_DEBUG
2204 old_state = GST_STATE (element);
2206 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2207 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2208 gst_element_state_get_name (pending));
2212 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2214 GST_STATE_BROADCAST (element);
2215 GST_OBJECT_UNLOCK (element);
2221 GST_OBJECT_UNLOCK (element);
2226 /* Not static because GstBin has manual state handling too */
2228 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2229 GstState newstate, GstState pending)
2231 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2232 GstMessage *message;
2234 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2235 "notifying about state-changed %s to %s (%s pending)",
2236 gst_element_state_get_name (oldstate),
2237 gst_element_state_get_name (newstate),
2238 gst_element_state_get_name (pending));
2240 if (klass->state_changed)
2241 klass->state_changed (element, oldstate, newstate, pending);
2243 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2244 oldstate, newstate, pending);
2245 gst_element_post_message (element, message);
2249 * gst_element_continue_state:
2250 * @element: a #GstElement to continue the state change of.
2251 * @ret: The previous state return value
2253 * Commit the state change of the element and proceed to the next
2254 * pending state if any. This function is used
2255 * by elements that do asynchronous state changes.
2256 * The core will normally call this method automatically when an
2257 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2259 * If after calling this method the element still has not reached
2260 * the pending state, the next state change is performed.
2262 * This method is used internally and should normally not be called by plugins
2265 * Returns: The result of the commit state change.
2269 GstStateChangeReturn
2270 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2272 GstStateChangeReturn old_ret;
2273 GstState old_state, old_next;
2274 GstState current, next, pending;
2275 GstStateChange transition;
2277 GST_OBJECT_LOCK (element);
2278 old_ret = GST_STATE_RETURN (element);
2279 GST_STATE_RETURN (element) = ret;
2280 pending = GST_STATE_PENDING (element);
2282 /* check if there is something to commit */
2283 if (pending == GST_STATE_VOID_PENDING)
2284 goto nothing_pending;
2286 old_state = GST_STATE (element);
2287 /* this is the state we should go to next */
2288 old_next = GST_STATE_NEXT (element);
2289 /* update current state */
2290 current = GST_STATE (element) = old_next;
2292 /* see if we reached the final state */
2293 if (pending == current)
2296 next = GST_STATE_GET_NEXT (current, pending);
2297 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2299 GST_STATE_NEXT (element) = next;
2301 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2302 GST_OBJECT_UNLOCK (element);
2304 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2305 "committing state from %s to %s, pending %s, next %s",
2306 gst_element_state_get_name (old_state),
2307 gst_element_state_get_name (old_next),
2308 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2310 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2312 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2313 "continue state change %s to %s, final %s",
2314 gst_element_state_get_name (current),
2315 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2317 ret = gst_element_change_state (element, transition);
2323 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2324 GST_OBJECT_UNLOCK (element);
2329 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2330 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2332 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2333 "completed state change to %s", gst_element_state_get_name (pending));
2334 GST_OBJECT_UNLOCK (element);
2336 /* don't post silly messages with the same state. This can happen
2337 * when an element state is changed to what it already was. For bins
2338 * this can be the result of a lost state, which we check with the
2339 * previous return value.
2340 * We do signal the cond though as a _get_state() might be blocking
2342 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2343 _priv_gst_element_state_changed (element, old_state, old_next,
2344 GST_STATE_VOID_PENDING);
2346 GST_STATE_BROADCAST (element);
2353 * gst_element_lost_state:
2354 * @element: a #GstElement the state is lost of
2356 * Brings the element to the lost state. The current state of the
2357 * element is copied to the pending state so that any call to
2358 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2360 * An ASYNC_START message is posted. If the element was PLAYING, it will
2361 * go to PAUSED. The element will be restored to its PLAYING state by
2362 * the parent pipeline when it prerolls again.
2364 * This is mostly used for elements that lost their preroll buffer
2365 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2366 * they will go to their pending state again when a new preroll buffer is
2367 * queued. This function can only be called when the element is currently
2368 * not in error or an async state change.
2370 * This function is used internally and should normally not be called from
2371 * plugins or applications.
2374 gst_element_lost_state (GstElement * element)
2376 GstState old_state, new_state;
2377 GstMessage *message;
2379 g_return_if_fail (GST_IS_ELEMENT (element));
2381 GST_OBJECT_LOCK (element);
2382 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2385 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2386 goto only_async_start;
2388 old_state = GST_STATE (element);
2390 /* when we were PLAYING, the new state is PAUSED. We will also not
2391 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2392 * when we preroll. */
2393 if (old_state > GST_STATE_PAUSED)
2394 new_state = GST_STATE_PAUSED;
2396 new_state = old_state;
2398 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2399 "lost state of %s to %s", gst_element_state_get_name (old_state),
2400 gst_element_state_get_name (new_state));
2402 GST_STATE (element) = new_state;
2403 GST_STATE_NEXT (element) = new_state;
2404 GST_STATE_PENDING (element) = new_state;
2405 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2406 GST_OBJECT_UNLOCK (element);
2408 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2410 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2411 gst_element_post_message (element, message);
2417 GST_OBJECT_UNLOCK (element);
2422 GST_OBJECT_UNLOCK (element);
2424 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2425 gst_element_post_message (element, message);
2431 * gst_element_set_state:
2432 * @element: a #GstElement to change state of.
2433 * @state: the element's new #GstState.
2435 * Sets the state of the element. This function will try to set the
2436 * requested state by going through all the intermediary states and calling
2437 * the class's state change function for each.
2439 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2440 * element will perform the remainder of the state change asynchronously in
2442 * An application can use gst_element_get_state() to wait for the completion
2443 * of the state change or it can wait for a %GST_MESSAGE_ASYNC_DONE or
2444 * %GST_MESSAGE_STATE_CHANGED on the bus.
2446 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2447 * #GST_STATE_CHANGE_ASYNC.
2449 * Returns: Result of the state change using #GstStateChangeReturn.
2453 GstStateChangeReturn
2454 gst_element_set_state (GstElement * element, GstState state)
2456 GstElementClass *oclass;
2457 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2459 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2461 oclass = GST_ELEMENT_GET_CLASS (element);
2463 if (oclass->set_state)
2464 result = (oclass->set_state) (element, state);
2470 * default set state function, calculates the next state based
2471 * on current state and calls the change_state function
2473 static GstStateChangeReturn
2474 gst_element_set_state_func (GstElement * element, GstState state)
2476 GstState current, next, old_pending;
2477 GstStateChangeReturn ret;
2478 GstStateChange transition;
2479 GstStateChangeReturn old_ret;
2481 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2483 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2484 gst_element_state_get_name (state));
2486 /* state lock is taken to protect the set_state() and get_state()
2487 * procedures, it does not lock any variables. */
2488 GST_STATE_LOCK (element);
2490 /* now calculate how to get to the new state */
2491 GST_OBJECT_LOCK (element);
2492 old_ret = GST_STATE_RETURN (element);
2493 /* previous state change returned an error, remove all pending
2494 * and next states */
2495 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2496 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2497 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2498 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2501 current = GST_STATE (element);
2502 next = GST_STATE_NEXT (element);
2503 old_pending = GST_STATE_PENDING (element);
2505 /* this is the (new) state we should go to. TARGET is the last state we set on
2507 if (state != GST_STATE_TARGET (element)) {
2508 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2509 "setting target state to %s", gst_element_state_get_name (state));
2510 GST_STATE_TARGET (element) = state;
2511 /* increment state cookie so that we can track each state change. We only do
2512 * this if this is actually a new state change. */
2513 element->state_cookie++;
2515 GST_STATE_PENDING (element) = state;
2517 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2518 "current %s, old_pending %s, next %s, old return %s",
2519 gst_element_state_get_name (current),
2520 gst_element_state_get_name (old_pending),
2521 gst_element_state_get_name (next),
2522 gst_element_state_change_return_get_name (old_ret));
2524 /* if the element was busy doing a state change, we just update the
2525 * target state, it'll get to it async then. */
2526 if (old_pending != GST_STATE_VOID_PENDING) {
2527 /* upwards state change will happen ASYNC */
2528 if (old_pending <= state)
2530 /* element is going to this state already */
2531 else if (next == state)
2533 /* element was performing an ASYNC upward state change and
2534 * we request to go downward again. Start from the next pending
2536 else if (next > state
2537 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2541 next = GST_STATE_GET_NEXT (current, state);
2542 /* now we store the next state */
2543 GST_STATE_NEXT (element) = next;
2544 /* mark busy, we need to check that there is actually a state change
2545 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2546 * the default element change_state function has no way to know what the
2547 * old value was... could consider this a FIXME...*/
2548 if (current != next)
2549 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2551 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2553 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2554 "%s: setting state from %s to %s",
2555 (next != state ? "intermediate" : "final"),
2556 gst_element_state_get_name (current), gst_element_state_get_name (next));
2558 /* now signal any waiters, they will error since the cookie was incremented */
2559 GST_STATE_BROADCAST (element);
2561 GST_OBJECT_UNLOCK (element);
2563 ret = gst_element_change_state (element, transition);
2565 GST_STATE_UNLOCK (element);
2567 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2568 gst_element_state_change_return_get_name (ret));
2574 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2575 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2576 "element was busy with async state change");
2577 GST_OBJECT_UNLOCK (element);
2579 GST_STATE_UNLOCK (element);
2581 return GST_STATE_CHANGE_ASYNC;
2586 * gst_element_change_state:
2587 * @element: a #GstElement
2588 * @transition: the requested transition
2590 * Perform @transition on @element.
2592 * This function must be called with STATE_LOCK held and is mainly used
2595 * Returns: the #GstStateChangeReturn of the state transition.
2597 GstStateChangeReturn
2598 gst_element_change_state (GstElement * element, GstStateChange transition)
2600 GstElementClass *oclass;
2601 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2603 oclass = GST_ELEMENT_GET_CLASS (element);
2605 /* call the state change function so it can set the state */
2606 if (oclass->change_state)
2607 ret = (oclass->change_state) (element, transition);
2609 ret = GST_STATE_CHANGE_FAILURE;
2612 case GST_STATE_CHANGE_FAILURE:
2613 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2614 "have FAILURE change_state return");
2615 /* state change failure */
2616 gst_element_abort_state (element);
2618 case GST_STATE_CHANGE_ASYNC:
2622 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2623 "element will change state ASYNC");
2625 target = GST_STATE_TARGET (element);
2627 if (target > GST_STATE_READY)
2630 /* else we just continue the state change downwards */
2631 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2632 "forcing commit state %s <= %s",
2633 gst_element_state_get_name (target),
2634 gst_element_state_get_name (GST_STATE_READY));
2636 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2639 case GST_STATE_CHANGE_SUCCESS:
2640 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2641 "element changed state SUCCESS");
2642 /* we can commit the state now which will proceeed to
2644 ret = gst_element_continue_state (element, ret);
2646 case GST_STATE_CHANGE_NO_PREROLL:
2647 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2648 "element changed state NO_PREROLL");
2649 /* we can commit the state now which will proceeed to
2651 ret = gst_element_continue_state (element, ret);
2654 goto invalid_return;
2657 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2662 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2670 GST_OBJECT_LOCK (element);
2671 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2672 g_critical ("%s: unknown return value %d from a state change function",
2673 GST_ELEMENT_NAME (element), ret);
2675 /* we are in error now */
2676 ret = GST_STATE_CHANGE_FAILURE;
2677 GST_STATE_RETURN (element) = ret;
2678 GST_OBJECT_UNLOCK (element);
2684 /* gst_iterator_fold functions for pads_activate
2685 * Stop the iterator if activating one pad failed, but only if that pad
2686 * has not been removed from the element. */
2688 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2690 GstPad *pad = g_value_get_object (vpad);
2691 gboolean cont = TRUE;
2693 if (!gst_pad_set_active (pad, *active)) {
2694 if (GST_PAD_PARENT (pad) != NULL) {
2696 g_value_set_boolean (ret, FALSE);
2703 /* returns false on error or early cutout of the fold, true if all
2704 * pads in @iter were (de)activated successfully. */
2706 iterator_activate_fold_with_resync (GstIterator * iter,
2707 GstIteratorFoldFunction func, gpointer user_data)
2709 GstIteratorResult ires;
2712 /* no need to unset this later, it's just a boolean */
2713 g_value_init (&ret, G_TYPE_BOOLEAN);
2714 g_value_set_boolean (&ret, TRUE);
2717 ires = gst_iterator_fold (iter, func, &ret, user_data);
2719 case GST_ITERATOR_RESYNC:
2720 /* need to reset the result again */
2721 g_value_set_boolean (&ret, TRUE);
2722 gst_iterator_resync (iter);
2724 case GST_ITERATOR_DONE:
2725 /* all pads iterated, return collected value */
2728 /* iterator returned _ERROR or premature end with _OK,
2729 * mark an error and exit */
2730 g_value_set_boolean (&ret, FALSE);
2735 /* return collected value */
2736 return g_value_get_boolean (&ret);
2739 /* is called with STATE_LOCK
2741 * Pads are activated from source pads to sinkpads.
2744 gst_element_pads_activate (GstElement * element, gboolean active)
2749 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2750 "%s pads", active ? "activate" : "deactivate");
2752 iter = gst_element_iterate_src_pads (element);
2754 iterator_activate_fold_with_resync (iter,
2755 (GstIteratorFoldFunction) activate_pads, &active);
2756 gst_iterator_free (iter);
2757 if (G_UNLIKELY (!res))
2760 iter = gst_element_iterate_sink_pads (element);
2762 iterator_activate_fold_with_resync (iter,
2763 (GstIteratorFoldFunction) activate_pads, &active);
2764 gst_iterator_free (iter);
2765 if (G_UNLIKELY (!res))
2768 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2769 "pad %sactivation successful", active ? "" : "de");
2776 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2777 "pad %sactivation failed", active ? "" : "de");
2782 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2783 "sink pads_activate failed");
2788 /* is called with STATE_LOCK */
2789 static GstStateChangeReturn
2790 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2792 GstState state, next;
2793 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2795 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2797 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2798 next = GST_STATE_TRANSITION_NEXT (transition);
2800 /* if the element already is in the given state, we just return success */
2801 if (next == GST_STATE_VOID_PENDING || state == next)
2804 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2805 "default handler tries setting state from %s to %s (%04x)",
2806 gst_element_state_get_name (state),
2807 gst_element_state_get_name (next), transition);
2809 switch (transition) {
2810 case GST_STATE_CHANGE_NULL_TO_READY:
2812 case GST_STATE_CHANGE_READY_TO_PAUSED:
2813 if (!gst_element_pads_activate (element, TRUE)) {
2814 result = GST_STATE_CHANGE_FAILURE;
2817 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2819 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2821 case GST_STATE_CHANGE_PAUSED_TO_READY:
2822 case GST_STATE_CHANGE_READY_TO_NULL:{
2825 /* deactivate pads in both cases, since they are activated on
2826 ready->paused but the element might not have made it to paused */
2827 if (!gst_element_pads_activate (element, FALSE)) {
2828 result = GST_STATE_CHANGE_FAILURE;
2831 /* Remove all non-persistent contexts */
2832 GST_OBJECT_LOCK (element);
2833 for (l = element->contexts; l;) {
2834 GstContext *context = l->data;
2836 if (!gst_context_is_persistent (context)) {
2839 gst_context_unref (context);
2841 element->contexts = g_list_delete_link (element->contexts, l);
2847 GST_OBJECT_UNLOCK (element);
2851 /* this will catch real but unhandled state changes;
2852 * can only be caused by:
2853 * - a new state was added
2854 * - somehow the element was asked to jump across an intermediate state
2856 g_warning ("Unhandled state change from %s to %s",
2857 gst_element_state_get_name (state),
2858 gst_element_state_get_name (next));
2865 GST_OBJECT_LOCK (element);
2866 result = GST_STATE_RETURN (element);
2867 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2868 "element is already in the %s state",
2869 gst_element_state_get_name (state));
2870 GST_OBJECT_UNLOCK (element);
2877 * gst_element_get_factory:
2878 * @element: a #GstElement to request the element factory of.
2880 * Retrieves the factory that was used to create this element.
2882 * Returns: (transfer none): the #GstElementFactory used for creating this
2883 * element. no refcounting is needed.
2886 gst_element_get_factory (GstElement * element)
2888 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2890 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2894 gst_element_dispose (GObject * object)
2896 GstElement *element = GST_ELEMENT_CAST (object);
2899 GstElementClass *oclass;
2902 oclass = GST_ELEMENT_GET_CLASS (element);
2904 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2906 if (GST_STATE (element) != GST_STATE_NULL)
2909 /* start by releasing all request pads, this might also remove some dynamic
2911 walk = element->pads;
2913 GstPad *pad = GST_PAD_CAST (walk->data);
2917 if (oclass->release_pad && GST_PAD_PAD_TEMPLATE (pad) &&
2918 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
2919 == GST_PAD_REQUEST) {
2920 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2921 "removing request pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2922 oclass->release_pad (element, pad);
2924 /* in case the release_pad function removed the next pad too */
2925 if (walk && g_list_position (element->pads, walk) == -1)
2926 walk = element->pads;
2929 /* remove the remaining pads */
2930 while (element->pads) {
2931 GstPad *pad = GST_PAD_CAST (element->pads->data);
2932 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2933 "removing pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2934 if (!gst_element_remove_pad (element, pad)) {
2935 /* only happens when someone unparented our pad.. */
2936 g_critical ("failed to remove pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2941 GST_OBJECT_LOCK (element);
2942 clock_p = &element->clock;
2943 bus_p = &element->bus;
2944 gst_object_replace ((GstObject **) clock_p, NULL);
2945 gst_object_replace ((GstObject **) bus_p, NULL);
2946 g_list_free_full (element->contexts, (GDestroyNotify) gst_context_unref);
2947 GST_OBJECT_UNLOCK (element);
2949 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2951 G_OBJECT_CLASS (parent_class)->dispose (object);
2960 is_locked = GST_ELEMENT_IS_LOCKED_STATE (element);
2962 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2964 "You need to explicitly set elements to the NULL state before\n"
2965 "dropping the final reference, to allow them to clean up.\n"
2966 "This problem may also be caused by a refcounting bug in the\n"
2967 "application or some element.\n",
2968 GST_OBJECT_NAME (element),
2969 gst_element_state_get_name (GST_STATE (element)),
2970 is_locked ? " (locked)" : "");
2976 gst_element_finalize (GObject * object)
2978 GstElement *element = GST_ELEMENT_CAST (object);
2980 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2982 g_cond_clear (&element->state_cond);
2983 g_rec_mutex_clear (&element->state_lock);
2985 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2987 G_OBJECT_CLASS (parent_class)->finalize (object);
2991 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2995 g_return_if_fail (GST_IS_ELEMENT (element));
2997 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2999 GST_OBJECT_LOCK (element);
3000 bus_p = &GST_ELEMENT_BUS (element);
3001 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
3002 GST_OBJECT_UNLOCK (element);
3006 * gst_element_set_bus:
3007 * @element: a #GstElement to set the bus of.
3008 * @bus: (transfer none): the #GstBus to set.
3010 * Sets the bus of the element. Increases the refcount on the bus.
3011 * For internal use only, unless you're testing elements.
3016 gst_element_set_bus (GstElement * element, GstBus * bus)
3018 GstElementClass *oclass;
3020 g_return_if_fail (GST_IS_ELEMENT (element));
3022 oclass = GST_ELEMENT_GET_CLASS (element);
3024 if (oclass->set_bus)
3025 oclass->set_bus (element, bus);
3029 * gst_element_get_bus:
3030 * @element: a #GstElement to get the bus of.
3032 * Returns the bus of the element. Note that only a #GstPipeline will provide a
3033 * bus for the application.
3035 * Returns: (transfer full): the element's #GstBus. unref after usage.
3040 gst_element_get_bus (GstElement * element)
3042 GstBus *result = NULL;
3044 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3046 GST_OBJECT_LOCK (element);
3047 if ((result = GST_ELEMENT_BUS (element)))
3048 gst_object_ref (result);
3049 GST_OBJECT_UNLOCK (element);
3051 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,
3058 gst_element_set_context_default (GstElement * element, GstContext * context)
3060 const gchar *context_type;
3063 GST_OBJECT_LOCK (element);
3064 context_type = gst_context_get_context_type (context);
3065 for (l = element->contexts; l; l = l->next) {
3066 GstContext *tmp = l->data;
3067 const gchar *tmp_type = gst_context_get_context_type (tmp);
3069 /* Always store newest context but never replace
3070 * a persistent one by a non-persistent one */
3071 if (strcmp (context_type, tmp_type) == 0 &&
3072 (gst_context_is_persistent (context) ||
3073 !gst_context_is_persistent (tmp))) {
3074 gst_context_replace ((GstContext **) & l->data, context);
3078 /* Not found? Add */
3081 g_list_prepend (element->contexts, gst_context_ref (context));
3083 GST_OBJECT_UNLOCK (element);
3087 * gst_element_set_context:
3088 * @element: a #GstElement to set the context of.
3089 * @context: (transfer none): the #GstContext to set.
3091 * Sets the context of the element. Increases the refcount of the context.
3096 gst_element_set_context (GstElement * element, GstContext * context)
3098 GstElementClass *oclass;
3100 g_return_if_fail (GST_IS_ELEMENT (element));
3102 oclass = GST_ELEMENT_GET_CLASS (element);
3104 GST_CAT_DEBUG_OBJECT (GST_CAT_CONTEXT, element,
3105 "set context %p %" GST_PTR_FORMAT, context,
3106 gst_context_get_structure (context));
3108 if (oclass->set_context)
3109 oclass->set_context (element, context);
3113 * gst_element_get_contexts:
3114 * @element: a #GstElement to set the context of.
3116 * Gets the contexts set on the element.
3120 * Returns: (element-type Gst.Context) (transfer full): List of #GstContext
3125 gst_element_get_contexts (GstElement * element)
3129 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
3131 GST_OBJECT_LOCK (element);
3132 ret = g_list_copy_deep (element->contexts, (GCopyFunc) gst_context_ref, NULL);
3133 GST_OBJECT_UNLOCK (element);
3139 _match_context_type (GstContext * c1, const gchar * context_type)
3141 const gchar *c1_type;
3143 c1_type = gst_context_get_context_type (c1);
3145 return g_strcmp0 (c1_type, context_type);
3149 * gst_element_get_context_unlocked:
3150 * @element: a #GstElement to get the context of.
3151 * @context_type: a name of a context to retrieve
3153 * Gets the context with @context_type set on the element or NULL.
3155 * Returns: (transfer full): A #GstContext or NULL
3160 gst_element_get_context_unlocked (GstElement * element,
3161 const gchar * context_type)
3163 GstContext *ret = NULL;
3166 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
3169 g_list_find_custom (element->contexts, context_type,
3170 (GCompareFunc) _match_context_type);
3171 if (node && node->data)
3172 ret = gst_context_ref (node->data);
3178 * gst_element_get_context:
3179 * @element: a #GstElement to get the context of.
3180 * @context_type: a name of a context to retrieve
3182 * Gets the context with @context_type set on the element or NULL.
3186 * Returns: (transfer full): A #GstContext or NULL
3191 gst_element_get_context (GstElement * element, const gchar * context_type)
3193 GstContext *ret = NULL;
3195 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
3197 GST_OBJECT_LOCK (element);
3198 ret = gst_element_get_context_unlocked (element, context_type);
3199 GST_OBJECT_UNLOCK (element);