2 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
3 * 2004 Wim Taymans <wim@fluendo.com>
5 * gstelement.c: The base element, all elements derive from this
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Library General Public
9 * License as published by the Free Software Foundation; either
10 * version 2 of the License, or (at your option) any later version.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Library General Public License for more details.
17 * You should have received a copy of the GNU Library General Public
18 * License along with this library; if not, write to the
19 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 * Boston, MA 02111-1307, USA.
25 * @short_description: Abstract base class for all pipeline elements
26 * @see_also: #GstElementFactory, #GstPad
28 * GstElement is the abstract base class needed to construct an element that
29 * can be used in a GStreamer pipeline. Please refer to the plugin writers
30 * guide for more information on creating #GstElement subclasses.
32 * The name of a #GstElement can be get with gst_element_get_name() and set with
33 * gst_element_set_name(). For speed, GST_ELEMENT_NAME() can be used in the
34 * core when using the appropriate locking. Do not use this in plug-ins or
35 * applications in order to retain ABI compatibility.
37 * 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"
96 #include "gst-i18n-lib.h"
97 #include "glib-compat-private.h"
99 /* Element signals and args */
115 static void gst_element_class_init (GstElementClass * klass);
116 static void gst_element_init (GstElement * element);
117 static void gst_element_base_class_init (gpointer g_class);
118 static void gst_element_base_class_finalize (gpointer g_class);
120 static void gst_element_dispose (GObject * object);
121 static void gst_element_finalize (GObject * object);
123 static GstStateChangeReturn gst_element_change_state_func (GstElement * element,
124 GstStateChange transition);
125 static GstStateChangeReturn gst_element_get_state_func (GstElement * element,
126 GstState * state, GstState * pending, GstClockTime timeout);
127 static GstStateChangeReturn gst_element_set_state_func (GstElement * element,
129 static gboolean gst_element_set_clock_func (GstElement * element,
131 static void gst_element_set_bus_func (GstElement * element, GstBus * bus);
133 static gboolean gst_element_default_send_event (GstElement * element,
135 static gboolean gst_element_default_query (GstElement * element,
138 static GstPadTemplate
139 * gst_element_class_get_request_pad_template (GstElementClass *
140 element_class, const gchar * name);
142 static GstObjectClass *parent_class = NULL;
143 static guint gst_element_signals[LAST_SIGNAL] = { 0 };
145 /* this is used in gstelementfactory.c:gst_element_register() */
146 GQuark __gst_elementclass_factory = 0;
149 gst_element_get_type (void)
151 static volatile gsize gst_element_type = 0;
153 if (g_once_init_enter (&gst_element_type)) {
155 static const GTypeInfo element_info = {
156 sizeof (GstElementClass),
157 gst_element_base_class_init,
158 gst_element_base_class_finalize,
159 (GClassInitFunc) gst_element_class_init,
164 (GInstanceInitFunc) gst_element_init,
168 _type = g_type_register_static (GST_TYPE_OBJECT, "GstElement",
169 &element_info, G_TYPE_FLAG_ABSTRACT);
171 __gst_elementclass_factory =
172 g_quark_from_static_string ("GST_ELEMENTCLASS_FACTORY");
173 g_once_init_leave (&gst_element_type, _type);
175 return gst_element_type;
179 gst_element_class_init (GstElementClass * klass)
181 GObjectClass *gobject_class;
183 gobject_class = (GObjectClass *) klass;
185 parent_class = g_type_class_peek_parent (klass);
188 * GstElement::pad-added:
189 * @gstelement: the object which received the signal
190 * @new_pad: the pad that has been added
192 * a new #GstPad has been added to the element. Note that this signal will
193 * usually be emitted from the context of the streaming thread. Also keep in
194 * mind that if you add new elements to the pipeline in the signal handler
195 * you will need to set them to the desired target state with
196 * gst_element_set_state() or gst_element_sync_state_with_parent().
198 gst_element_signals[PAD_ADDED] =
199 g_signal_new ("pad-added", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
200 G_STRUCT_OFFSET (GstElementClass, pad_added), NULL, NULL,
201 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
203 * GstElement::pad-removed:
204 * @gstelement: the object which received the signal
205 * @old_pad: the pad that has been removed
207 * a #GstPad has been removed from the element
209 gst_element_signals[PAD_REMOVED] =
210 g_signal_new ("pad-removed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
211 G_STRUCT_OFFSET (GstElementClass, pad_removed), NULL, NULL,
212 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
214 * GstElement::no-more-pads:
215 * @gstelement: the object which received the signal
217 * This signals that the element will not generate more dynamic pads.
218 * Note that this signal will usually be emitted from the context of
219 * the streaming thread.
221 gst_element_signals[NO_MORE_PADS] =
222 g_signal_new ("no-more-pads", G_TYPE_FROM_CLASS (klass),
223 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstElementClass, no_more_pads), NULL,
224 NULL, g_cclosure_marshal_generic, G_TYPE_NONE, 0);
226 gobject_class->dispose = gst_element_dispose;
227 gobject_class->finalize = gst_element_finalize;
229 klass->change_state = GST_DEBUG_FUNCPTR (gst_element_change_state_func);
230 klass->set_state = GST_DEBUG_FUNCPTR (gst_element_set_state_func);
231 klass->get_state = GST_DEBUG_FUNCPTR (gst_element_get_state_func);
232 klass->set_clock = GST_DEBUG_FUNCPTR (gst_element_set_clock_func);
233 klass->set_bus = GST_DEBUG_FUNCPTR (gst_element_set_bus_func);
234 klass->query = GST_DEBUG_FUNCPTR (gst_element_default_query);
235 klass->send_event = GST_DEBUG_FUNCPTR (gst_element_default_send_event);
236 klass->numpadtemplates = 0;
238 klass->elementfactory = NULL;
242 gst_element_base_class_init (gpointer g_class)
244 GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
245 GList *node, *padtemplates;
247 /* Copy the element details here so elements can inherit the
248 * details from their base class and classes only need to set
249 * the details in class_init instead of base_init */
250 element_class->metadata =
251 element_class->metadata ? gst_structure_copy (element_class->metadata) :
252 gst_structure_new_empty ("metadata");
254 /* Copy the pad templates so elements inherit them
255 * from their base class but elements can add pad templates in class_init
256 * instead of base_init.
258 padtemplates = g_list_copy (element_class->padtemplates);
259 for (node = padtemplates; node != NULL; node = node->next) {
260 GstPadTemplate *tmpl = (GstPadTemplate *) node->data;
261 gst_object_ref (tmpl);
263 element_class->padtemplates = padtemplates;
265 /* set the factory, see gst_element_register() */
266 element_class->elementfactory =
267 g_type_get_qdata (G_TYPE_FROM_CLASS (element_class),
268 __gst_elementclass_factory);
269 GST_DEBUG ("type %s : factory %p", G_OBJECT_CLASS_NAME (element_class),
270 element_class->elementfactory);
274 gst_element_base_class_finalize (gpointer g_class)
276 GstElementClass *klass = GST_ELEMENT_CLASS (g_class);
278 g_list_foreach (klass->padtemplates, (GFunc) gst_object_unref, NULL);
279 g_list_free (klass->padtemplates);
281 gst_structure_free (klass->metadata);
285 gst_element_init (GstElement * element)
287 GST_STATE (element) = GST_STATE_NULL;
288 GST_STATE_TARGET (element) = GST_STATE_NULL;
289 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
290 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
291 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
293 g_rec_mutex_init (&element->state_lock);
294 g_cond_init (&element->state_cond);
298 * gst_element_release_request_pad:
299 * @element: a #GstElement to release the request pad of.
300 * @pad: the #GstPad to release.
302 * Makes the element free the previously requested pad as obtained
303 * with gst_element_get_request_pad().
305 * This does not unref the pad. If the pad was created by using
306 * gst_element_get_request_pad(), gst_element_release_request_pad() needs to be
307 * followed by gst_object_unref() to free the @pad.
312 gst_element_release_request_pad (GstElement * element, GstPad * pad)
314 GstElementClass *oclass;
316 g_return_if_fail (GST_IS_ELEMENT (element));
317 g_return_if_fail (GST_IS_PAD (pad));
318 g_return_if_fail (GST_PAD_PAD_TEMPLATE (pad) == NULL ||
319 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad)) ==
322 oclass = GST_ELEMENT_GET_CLASS (element);
324 /* if the element implements a custom release function we call that, else we
325 * simply remove the pad from the element */
326 if (oclass->release_pad)
327 (oclass->release_pad) (element, pad);
329 gst_element_remove_pad (element, pad);
333 * gst_element_provide_clock:
334 * @element: a #GstElement to query
336 * Get the clock provided by the given element.
337 * <note>An element is only required to provide a clock in the PAUSED
338 * state. Some elements can provide a clock in other states.</note>
340 * Returns: (transfer full): the GstClock provided by the element or %NULL
341 * if no clock could be provided. Unref after usage.
346 gst_element_provide_clock (GstElement * element)
348 GstClock *result = NULL;
349 GstElementClass *oclass;
351 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
353 oclass = GST_ELEMENT_GET_CLASS (element);
355 if (oclass->provide_clock)
356 result = oclass->provide_clock (element);
362 gst_element_set_clock_func (GstElement * element, GstClock * clock)
366 GST_OBJECT_LOCK (element);
367 clock_p = &element->clock;
368 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
369 GST_OBJECT_UNLOCK (element);
375 * gst_element_set_clock:
376 * @element: a #GstElement to set the clock for.
377 * @clock: the #GstClock to set for the element.
379 * Sets the clock for the element. This function increases the
380 * refcount on the clock. Any previously set clock on the object
383 * Returns: %TRUE if the element accepted the clock. An element can refuse a
384 * clock when it, for example, is not able to slave its internal clock to the
385 * @clock or when it requires a specific clock to operate.
390 gst_element_set_clock (GstElement * element, GstClock * clock)
392 GstElementClass *oclass;
393 gboolean res = FALSE;
395 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
396 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
398 oclass = GST_ELEMENT_GET_CLASS (element);
400 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
402 if (oclass->set_clock)
403 res = oclass->set_clock (element, clock);
409 * gst_element_get_clock:
410 * @element: a #GstElement to get the clock of.
412 * Gets the currently configured clock of the element. This is the clock as was
413 * last set with gst_element_set_clock().
415 * Returns: (transfer full): the #GstClock of the element. unref after usage.
420 gst_element_get_clock (GstElement * element)
424 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
426 GST_OBJECT_LOCK (element);
427 if ((result = element->clock))
428 gst_object_ref (result);
429 GST_OBJECT_UNLOCK (element);
435 * gst_element_set_base_time:
436 * @element: a #GstElement.
437 * @time: the base time to set.
439 * Set the base time of an element. See gst_element_get_base_time().
444 gst_element_set_base_time (GstElement * element, GstClockTime time)
448 g_return_if_fail (GST_IS_ELEMENT (element));
450 GST_OBJECT_LOCK (element);
451 old = element->base_time;
452 element->base_time = time;
453 GST_OBJECT_UNLOCK (element);
455 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
456 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
457 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
461 * gst_element_get_base_time:
462 * @element: a #GstElement.
464 * Returns the base time of the element. The base time is the
465 * absolute time of the clock when this element was last put to
466 * PLAYING. Subtracting the base time from the clock time gives
467 * the running time of the element.
469 * Returns: the base time of the element.
474 gst_element_get_base_time (GstElement * element)
478 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
480 GST_OBJECT_LOCK (element);
481 result = element->base_time;
482 GST_OBJECT_UNLOCK (element);
488 * gst_element_set_start_time:
489 * @element: a #GstElement.
490 * @time: the base time to set.
492 * Set the start time of an element. The start time of the element is the
493 * running time of the element when it last went to the PAUSED state. In READY
494 * or after a flushing seek, it is set to 0.
496 * Toplevel elements like #GstPipeline will manage the start_time and
497 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
498 * on such a toplevel element will disable the distribution of the base_time to
499 * the children and can be useful if the application manages the base_time
500 * itself, for example if you want to synchronize capture from multiple
501 * pipelines, and you can also ensure that the pipelines have the same clock.
508 gst_element_set_start_time (GstElement * element, GstClockTime time)
512 g_return_if_fail (GST_IS_ELEMENT (element));
514 GST_OBJECT_LOCK (element);
515 old = GST_ELEMENT_START_TIME (element);
516 GST_ELEMENT_START_TIME (element) = time;
517 GST_OBJECT_UNLOCK (element);
519 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
520 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
521 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
525 * gst_element_get_start_time:
526 * @element: a #GstElement.
528 * Returns the start time of the element. The start time is the
529 * running time of the clock when this element was last put to PAUSED.
531 * Usually the start_time is managed by a toplevel element such as
536 * Returns: the start time of the element.
541 gst_element_get_start_time (GstElement * element)
545 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
547 GST_OBJECT_LOCK (element);
548 result = GST_ELEMENT_START_TIME (element);
549 GST_OBJECT_UNLOCK (element);
556 * gst_element_set_index:
557 * @element: a #GstElement.
558 * @index: (transfer none): a #GstIndex.
560 * Set @index on the element. The refcount of the index
561 * will be increased, any previously set index is unreffed.
566 gst_element_set_index (GstElement * element, GstIndex * index)
568 GstElementClass *oclass;
570 g_return_if_fail (GST_IS_ELEMENT (element));
571 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
573 oclass = GST_ELEMENT_GET_CLASS (element);
575 if (oclass->set_index)
576 oclass->set_index (element, index);
580 * gst_element_get_index:
581 * @element: a #GstElement.
583 * Gets the index from the element.
585 * Returns: (transfer full): a #GstIndex or %NULL when no index was set on the
586 * element. unref after usage.
591 gst_element_get_index (GstElement * element)
593 GstElementClass *oclass;
594 GstIndex *result = NULL;
596 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
598 oclass = GST_ELEMENT_GET_CLASS (element);
600 if (oclass->get_index)
601 result = oclass->get_index (element);
608 * gst_element_add_pad:
609 * @element: a #GstElement to add the pad to.
610 * @pad: (transfer full): the #GstPad to add to the element.
612 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
613 * see gst_object_set_parent() for refcounting information.
615 * Pads are not automatically activated so elements should perform the needed
616 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
617 * state. See gst_pad_set_active() for more information about activating pads.
619 * The pad and the element should be unlocked when calling this function.
621 * This function will emit the #GstElement::pad-added signal on the element.
623 * Returns: %TRUE if the pad could be added. This function can fail when
624 * a pad with the same name already existed or the pad already had another
630 gst_element_add_pad (GstElement * element, GstPad * pad)
635 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
636 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
638 /* locking pad to look at the name */
639 GST_OBJECT_LOCK (pad);
640 pad_name = g_strdup (GST_PAD_NAME (pad));
641 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
642 GST_STR_NULL (pad_name));
643 flushing = GST_PAD_IS_FLUSHING (pad);
644 GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_NEED_PARENT);
645 GST_OBJECT_UNLOCK (pad);
647 /* then check to see if there's already a pad by that name here */
648 GST_OBJECT_LOCK (element);
649 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
652 /* try to set the pad's parent */
653 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
654 GST_OBJECT_CAST (element))))
657 /* check for flushing pads */
658 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
659 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
660 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
661 "use gst_pad_set_active(pad,TRUE) before adding it.",
662 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
664 GST_OBJECT_LOCK (pad);
665 GST_PAD_UNSET_FLUSHING (pad);
666 GST_OBJECT_UNLOCK (pad);
671 /* add it to the list */
672 switch (gst_pad_get_direction (pad)) {
674 element->srcpads = g_list_prepend (element->srcpads, pad);
675 element->numsrcpads++;
678 element->sinkpads = g_list_prepend (element->sinkpads, pad);
679 element->numsinkpads++;
684 element->pads = g_list_prepend (element->pads, pad);
686 element->pads_cookie++;
687 GST_OBJECT_UNLOCK (element);
689 /* emit the PAD_ADDED signal */
690 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
697 g_critical ("Padname %s is not unique in element %s, not adding",
698 pad_name, GST_ELEMENT_NAME (element));
699 GST_OBJECT_UNLOCK (element);
706 ("Pad %s already has parent when trying to add to element %s",
707 pad_name, GST_ELEMENT_NAME (element));
708 GST_OBJECT_UNLOCK (element);
714 GST_OBJECT_LOCK (pad);
716 ("Trying to add pad %s to element %s, but it has no direction",
717 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
718 GST_OBJECT_UNLOCK (pad);
719 GST_OBJECT_UNLOCK (element);
725 * gst_element_remove_pad:
726 * @element: a #GstElement to remove pad from.
727 * @pad: (transfer none): the #GstPad to remove from the element.
729 * Removes @pad from @element. @pad will be destroyed if it has not been
730 * referenced elsewhere using gst_object_unparent().
732 * This function is used by plugin developers and should not be used
733 * by applications. Pads that were dynamically requested from elements
734 * with gst_element_get_request_pad() should be released with the
735 * gst_element_release_request_pad() function instead.
737 * Pads are not automatically deactivated so elements should perform the needed
738 * steps to deactivate the pad in case this pad is removed in the PAUSED or
739 * PLAYING state. See gst_pad_set_active() for more information about
742 * The pad and the element should be unlocked when calling this function.
744 * This function will emit the #GstElement::pad-removed signal on the element.
746 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
747 * pad does not belong to the provided element.
752 gst_element_remove_pad (GstElement * element, GstPad * pad)
756 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
757 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
759 /* locking pad to look at the name and parent */
760 GST_OBJECT_LOCK (pad);
761 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
762 GST_STR_NULL (GST_PAD_NAME (pad)));
764 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
766 GST_OBJECT_UNLOCK (pad);
769 if ((peer = gst_pad_get_peer (pad))) {
770 /* window for MT unsafeness, someone else could unlink here
771 * and then we call unlink with wrong pads. The unlink
772 * function would catch this and safely return failed. */
773 if (GST_PAD_IS_SRC (pad))
774 gst_pad_unlink (pad, peer);
776 gst_pad_unlink (peer, pad);
778 gst_object_unref (peer);
781 GST_OBJECT_LOCK (element);
782 /* remove it from the list */
783 switch (gst_pad_get_direction (pad)) {
785 element->srcpads = g_list_remove (element->srcpads, pad);
786 element->numsrcpads--;
789 element->sinkpads = g_list_remove (element->sinkpads, pad);
790 element->numsinkpads--;
793 g_critical ("Removing pad without direction???");
796 element->pads = g_list_remove (element->pads, pad);
798 element->pads_cookie++;
799 GST_OBJECT_UNLOCK (element);
801 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
802 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
804 gst_object_unparent (GST_OBJECT_CAST (pad));
811 /* locking order is element > pad */
812 GST_OBJECT_UNLOCK (pad);
814 GST_OBJECT_LOCK (element);
815 GST_OBJECT_LOCK (pad);
816 g_critical ("Padname %s:%s does not belong to element %s when removing",
817 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
818 GST_OBJECT_UNLOCK (pad);
819 GST_OBJECT_UNLOCK (element);
825 * gst_element_no_more_pads:
826 * @element: a #GstElement
828 * Use this function to signal that the element does not expect any more pads
829 * to show up in the current pipeline. This function should be called whenever
830 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
831 * pad templates use this in combination with autopluggers to figure out that
832 * the element is done initializing its pads.
834 * This function emits the #GstElement::no-more-pads signal.
839 gst_element_no_more_pads (GstElement * element)
841 g_return_if_fail (GST_IS_ELEMENT (element));
843 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
847 pad_compare_name (GstPad * pad1, const gchar * name)
851 GST_OBJECT_LOCK (pad1);
852 result = strcmp (GST_PAD_NAME (pad1), name);
853 GST_OBJECT_UNLOCK (pad1);
859 * gst_element_get_static_pad:
860 * @element: a #GstElement to find a static pad of.
861 * @name: the name of the static #GstPad to retrieve.
863 * Retrieves a pad from @element by name. This version only retrieves
864 * already-existing (i.e. 'static') pads.
866 * Returns: (transfer full): the requested #GstPad if found, otherwise %NULL.
872 gst_element_get_static_pad (GstElement * element, const gchar * name)
875 GstPad *result = NULL;
877 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
878 g_return_val_if_fail (name != NULL, NULL);
880 GST_OBJECT_LOCK (element);
882 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
884 result = GST_PAD_CAST (find->data);
885 gst_object_ref (result);
888 if (result == NULL) {
889 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
890 name, GST_ELEMENT_NAME (element));
892 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
893 GST_ELEMENT_NAME (element), name);
895 GST_OBJECT_UNLOCK (element);
901 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
902 const gchar * name, const GstCaps * caps)
904 GstPad *newpad = NULL;
905 GstElementClass *oclass;
907 oclass = GST_ELEMENT_GET_CLASS (element);
909 #ifndef G_DISABLE_CHECKS
910 /* Some sanity checking here */
914 /* Is this the template name? */
915 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
916 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
918 const gchar *str, *data;
921 /* Otherwise check if it's a valid name for the name template */
922 str = strchr (templ->name_template, '%');
923 g_return_val_if_fail (str != NULL, NULL);
924 g_return_val_if_fail (strncmp (templ->name_template, name,
925 str - templ->name_template) == 0, NULL);
926 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
928 data = name + (str - templ->name_template);
930 /* Can either be %s or %d or %u, do sanity checking for %d */
931 if (*(str + 1) == 'd') {
935 tmp = g_ascii_strtoll (data, &endptr, 10);
936 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
937 && *endptr == '\0', NULL);
938 } else if (*(str + 1) == 'u') {
942 tmp = g_ascii_strtoull (data, &endptr, 10);
943 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
947 pad = gst_element_get_static_pad (element, name);
949 gst_object_unref (pad);
950 /* FIXME 0.11: Change this to g_return_val_if_fail() */
951 g_critical ("Element %s already has a pad named %s, the behaviour of "
952 " gst_element_get_request_pad() for existing pads is undefined!",
953 GST_ELEMENT_NAME (element), name);
958 if (oclass->request_new_pad)
959 newpad = (oclass->request_new_pad) (element, templ, name, caps);
962 gst_object_ref (newpad);
968 * gst_element_get_request_pad:
969 * @element: a #GstElement to find a request pad of.
970 * @name: the name of the request #GstPad to retrieve.
972 * Retrieves a pad from the element by name (e.g. "src_\%d"). This version only
973 * retrieves request pads. The pad should be released with
974 * gst_element_release_request_pad().
976 * This method is slow and will be deprecated in the future. New code should
977 * use gst_element_request_pad() with the requested template.
979 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
980 * Release after usage.
983 gst_element_get_request_pad (GstElement * element, const gchar * name)
985 GstPadTemplate *templ = NULL;
987 const gchar *req_name = NULL;
988 gboolean templ_found = FALSE;
991 gchar *str, *endptr = NULL;
992 GstElementClass *class;
994 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
995 g_return_val_if_fail (name != NULL, NULL);
997 class = GST_ELEMENT_GET_CLASS (element);
999 /* if the name contains a %, we assume it's the complete template name. Get
1000 * the template and try to get a pad */
1001 if (strstr (name, "%")) {
1002 templ = gst_element_class_get_request_pad_template (class, name);
1007 /* there is no % in the name, try to find a matching template */
1008 list = class->padtemplates;
1009 while (!templ_found && list) {
1010 templ = (GstPadTemplate *) list->data;
1011 if (templ->presence == GST_PAD_REQUEST) {
1012 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1013 templ->name_template);
1014 /* see if we find an exact match */
1015 if (strcmp (name, templ->name_template) == 0) {
1020 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1021 and %d and %u, occurring at the end of the name_template, are the only
1023 else if ((str = strchr (templ->name_template, '%'))
1024 && strncmp (templ->name_template, name,
1025 str - templ->name_template) == 0
1026 && strlen (name) > str - templ->name_template) {
1027 data = name + (str - templ->name_template);
1028 if (*(str + 1) == 'd') {
1032 tmp = strtol (data, &endptr, 10);
1033 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1039 } else if (*(str + 1) == 'u') {
1043 tmp = strtoul (data, &endptr, 10);
1044 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1064 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1070 * gst_element_request_pad:
1071 * @element: a #GstElement to find a request pad of.
1072 * @templ: a #GstPadTemplate of which we want a pad of.
1073 * @name: (transfer none) (allow-none): the name of the request #GstPad
1074 * to retrieve. Can be %NULL.
1075 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1076 * request. Can be %NULL.
1078 * Retrieves a request pad from the element according to the provided template.
1079 * Pad templates can be looked up using
1080 * gst_element_factory_get_static_pad_templates().
1082 * The pad should be released with gst_element_release_request_pad().
1084 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1085 * Release after usage.
1090 gst_element_request_pad (GstElement * element,
1091 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1093 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1094 g_return_val_if_fail (templ != NULL, 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 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1127 gst_element_iterate_pads (GstElement * element)
1129 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1131 return gst_element_iterate_pad_list (element, &element->pads);
1135 * gst_element_iterate_src_pads:
1136 * @element: a #GstElement.
1138 * Retrieves an iterator of @element's source pads.
1140 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1146 gst_element_iterate_src_pads (GstElement * element)
1148 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1150 return gst_element_iterate_pad_list (element, &element->srcpads);
1154 * gst_element_iterate_sink_pads:
1155 * @element: a #GstElement.
1157 * Retrieves an iterator of @element's sink pads.
1159 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1165 gst_element_iterate_sink_pads (GstElement * element)
1167 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1169 return gst_element_iterate_pad_list (element, &element->sinkpads);
1173 * gst_element_class_add_pad_template:
1174 * @klass: the #GstElementClass to add the pad template to.
1175 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1177 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1178 * functions of classes. If a pad template with the same name as an already
1179 * existing one is added the old one is replaced by the new one.
1183 gst_element_class_add_pad_template (GstElementClass * klass,
1184 GstPadTemplate * templ)
1186 GList *template_list = klass->padtemplates;
1188 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1189 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1191 /* If we already have a pad template with the same name replace the
1193 while (template_list) {
1194 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1196 /* Found pad with the same name, replace and return */
1197 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1198 gst_object_unref (padtempl);
1199 template_list->data = templ;
1202 template_list = g_list_next (template_list);
1205 /* Take ownership of the floating ref */
1206 gst_object_ref_sink (templ);
1208 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1209 klass->numpadtemplates++;
1213 * gst_element_class_add_metadata:
1214 * @klass: class to set metadata for
1215 * @key: the key to set
1216 * @value: the value to set
1218 * Set @key with @value as metadata in @klass.
1221 gst_element_class_add_metadata (GstElementClass * klass,
1222 const gchar * key, const gchar * value)
1224 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1225 g_return_if_fail (key != NULL);
1226 g_return_if_fail (value != NULL);
1228 gst_structure_set ((GstStructure *) klass->metadata,
1229 key, G_TYPE_STRING, value, NULL);
1233 * gst_element_class_add_static_metadata:
1234 * @klass: class to set metadata for
1235 * @key: the key to set
1236 * @value: the value to set
1238 * Set @key with @value as metadata in @klass.
1240 * Same as gst_element_class_add_metadata(), but @value must be a static string
1241 * or an inlined string, as it will not be copied. (GStreamer plugins will
1242 * be made resident once loaded, so this function can be used even from
1243 * dynamically loaded plugins.)
1246 gst_element_class_add_static_metadata (GstElementClass * klass,
1247 const gchar * key, const gchar * value)
1249 GValue val = G_VALUE_INIT;
1251 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1252 g_return_if_fail (key != NULL);
1253 g_return_if_fail (value != NULL);
1255 g_value_init (&val, G_TYPE_STRING);
1256 g_value_set_static_string (&val, value);
1257 gst_structure_take_value ((GstStructure *) klass->metadata, key, &val);
1261 * gst_element_class_set_metadata:
1262 * @klass: class to set metadata for
1263 * @longname: The long English name of the element. E.g. "File Sink"
1264 * @classification: String describing the type of element, as an unordered list
1265 * separated with slashes ('/'). See draft-klass.txt of the design docs
1266 * for more details and common types. E.g: "Sink/File"
1267 * @description: Sentence describing the purpose of the element.
1268 * E.g: "Write stream to a file"
1269 * @author: Name and contact details of the author(s). Use \n to separate
1270 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1272 * Sets the detailed information for a #GstElementClass.
1273 * <note>This function is for use in _class_init functions only.</note>
1276 gst_element_class_set_metadata (GstElementClass * klass,
1277 const gchar * longname, const gchar * classification,
1278 const gchar * description, const gchar * author)
1280 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1282 gst_structure_set ((GstStructure *) klass->metadata,
1283 GST_ELEMENT_METADATA_LONGNAME, G_TYPE_STRING, longname,
1284 GST_ELEMENT_METADATA_KLASS, G_TYPE_STRING, classification,
1285 GST_ELEMENT_METADATA_DESCRIPTION, G_TYPE_STRING, description,
1286 GST_ELEMENT_METADATA_AUTHOR, G_TYPE_STRING, author, NULL);
1290 * gst_element_class_set_static_metadata:
1291 * @klass: class to set metadata for
1292 * @longname: The long English name of the element. E.g. "File Sink"
1293 * @classification: String describing the type of element, as an unordered list
1294 * separated with slashes ('/'). See draft-klass.txt of the design docs
1295 * for more details and common types. E.g: "Sink/File"
1296 * @description: Sentence describing the purpose of the element.
1297 * E.g: "Write stream to a file"
1298 * @author: Name and contact details of the author(s). Use \n to separate
1299 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1301 * Sets the detailed information for a #GstElementClass.
1302 * <note>This function is for use in _class_init functions only.</note>
1304 * Same as gst_element_class_set_metadata(), but @longname, @classification,
1305 * @description, and @author must be static strings or inlined strings, as
1306 * they will not be copied. (GStreamer plugins will be made resident once
1307 * loaded, so this function can be used even from dynamically loaded plugins.)
1310 gst_element_class_set_static_metadata (GstElementClass * klass,
1311 const gchar * longname, const gchar * classification,
1312 const gchar * description, const gchar * author)
1314 GstStructure *s = (GstStructure *) klass->metadata;
1315 GValue val = G_VALUE_INIT;
1317 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1319 g_value_init (&val, G_TYPE_STRING);
1321 g_value_set_static_string (&val, longname);
1322 gst_structure_set_value (s, GST_ELEMENT_METADATA_LONGNAME, &val);
1324 g_value_set_static_string (&val, classification);
1325 gst_structure_set_value (s, GST_ELEMENT_METADATA_KLASS, &val);
1327 g_value_set_static_string (&val, description);
1328 gst_structure_set_value (s, GST_ELEMENT_METADATA_DESCRIPTION, &val);
1330 g_value_set_static_string (&val, author);
1331 gst_structure_take_value (s, GST_ELEMENT_METADATA_AUTHOR, &val);
1335 * gst_element_class_get_metadata:
1336 * @klass: class to get metadata for
1337 * @key: the key to get
1339 * Get metadata with @key in @klass.
1341 * Returns: the metadata for @key.
1344 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1346 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1347 g_return_val_if_fail (key != NULL, NULL);
1349 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1353 * gst_element_class_get_pad_template_list:
1354 * @element_class: a #GstElementClass to get pad templates of.
1356 * Retrieves a list of the pad templates associated with @element_class. The
1357 * list must not be modified by the calling code.
1358 * <note>If you use this function in the #GInstanceInitFunc of an object class
1359 * that has subclasses, make sure to pass the g_class parameter of the
1360 * #GInstanceInitFunc here.</note>
1362 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1366 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1368 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1370 return element_class->padtemplates;
1374 * gst_element_class_get_pad_template:
1375 * @element_class: a #GstElementClass to get the pad template of.
1376 * @name: the name of the #GstPadTemplate to get.
1378 * Retrieves a padtemplate from @element_class with the given name.
1379 * <note>If you use this function in the #GInstanceInitFunc of an object class
1380 * that has subclasses, make sure to pass the g_class parameter of the
1381 * #GInstanceInitFunc here.</note>
1383 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1384 * if none was found. No unreferencing is necessary.
1387 gst_element_class_get_pad_template (GstElementClass *
1388 element_class, const gchar * name)
1392 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1393 g_return_val_if_fail (name != NULL, NULL);
1395 padlist = element_class->padtemplates;
1398 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1400 if (strcmp (padtempl->name_template, name) == 0)
1403 padlist = g_list_next (padlist);
1409 static GstPadTemplate *
1410 gst_element_class_get_request_pad_template (GstElementClass *
1411 element_class, const gchar * name)
1413 GstPadTemplate *tmpl;
1415 tmpl = gst_element_class_get_pad_template (element_class, name);
1416 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1422 /* get a random pad on element of the given direction.
1423 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1426 gst_element_get_random_pad (GstElement * element,
1427 gboolean need_linked, GstPadDirection dir)
1429 GstPad *result = NULL;
1432 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1436 GST_OBJECT_LOCK (element);
1437 pads = element->srcpads;
1440 GST_OBJECT_LOCK (element);
1441 pads = element->sinkpads;
1444 goto wrong_direction;
1446 for (; pads; pads = g_list_next (pads)) {
1447 GstPad *pad = GST_PAD_CAST (pads->data);
1449 GST_OBJECT_LOCK (pad);
1450 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1451 GST_DEBUG_PAD_NAME (pad));
1453 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1454 /* if we require a linked pad, and it is not linked, continue the
1456 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1457 GST_DEBUG_PAD_NAME (pad));
1458 GST_OBJECT_UNLOCK (pad);
1461 /* found a pad, stop search */
1462 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1463 GST_DEBUG_PAD_NAME (pad));
1464 GST_OBJECT_UNLOCK (pad);
1470 gst_object_ref (result);
1472 GST_OBJECT_UNLOCK (element);
1476 /* ERROR handling */
1479 g_warning ("unknown pad direction %d", dir);
1485 gst_element_default_send_event (GstElement * element, GstEvent * event)
1487 gboolean result = FALSE;
1490 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1491 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1492 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1495 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1496 "pushing %s event to random %s pad %s:%s",
1497 GST_EVENT_TYPE_NAME (event),
1498 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1499 GST_DEBUG_PAD_NAME (pad));
1501 result = gst_pad_push_event (pad, event);
1502 gst_object_unref (pad);
1504 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1505 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1506 gst_event_unref (event);
1512 * gst_element_send_event:
1513 * @element: a #GstElement to send the event to.
1514 * @event: (transfer full): the #GstEvent to send to the element.
1516 * Sends an event to an element. If the element doesn't implement an
1517 * event handler, the event will be pushed on a random linked sink pad for
1518 * upstream events or a random linked source pad for downstream events.
1520 * This function takes owership of the provided event so you should
1521 * gst_event_ref() it if you want to reuse the event after this call.
1523 * Returns: %TRUE if the event was handled.
1528 gst_element_send_event (GstElement * element, GstEvent * event)
1530 GstElementClass *oclass;
1531 gboolean result = FALSE;
1533 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1534 g_return_val_if_fail (event != NULL, FALSE);
1536 oclass = GST_ELEMENT_GET_CLASS (element);
1538 GST_STATE_LOCK (element);
1539 if (oclass->send_event) {
1540 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1541 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1542 result = oclass->send_event (element, event);
1544 GST_STATE_UNLOCK (element);
1551 * @element: a #GstElement to send the event to.
1552 * @rate: The new playback rate
1553 * @format: The format of the seek values
1554 * @flags: The optional seek flags.
1555 * @cur_type: The type and flags for the new current position
1556 * @cur: The value of the new current position
1557 * @stop_type: The type and flags for the new stop position
1558 * @stop: The value of the new stop position
1560 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1561 * the parameters. The seek event is sent to the element using
1562 * gst_element_send_event().
1564 * Returns: %TRUE if the event was handled.
1569 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1570 GstSeekFlags flags, GstSeekType cur_type, gint64 cur,
1571 GstSeekType stop_type, gint64 stop)
1576 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1579 gst_event_new_seek (rate, format, flags, cur_type, cur, stop_type, stop);
1580 result = gst_element_send_event (element, event);
1586 gst_element_default_query (GstElement * element, GstQuery * query)
1588 gboolean result = FALSE;
1591 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1593 result = gst_pad_query (pad, query);
1595 gst_object_unref (pad);
1597 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1599 GstPad *peer = gst_pad_get_peer (pad);
1602 result = gst_pad_query (peer, query);
1604 gst_object_unref (peer);
1606 gst_object_unref (pad);
1613 * gst_element_query:
1614 * @element: a #GstElement to perform the query on.
1615 * @query: (transfer none): the #GstQuery.
1617 * Performs a query on the given element.
1619 * For elements that don't implement a query handler, this function
1620 * forwards the query to a random srcpad or to the peer of a
1621 * random linked sinkpad of this element.
1623 * Please note that some queries might need a running pipeline to work.
1625 * Returns: TRUE if the query could be performed.
1630 gst_element_query (GstElement * element, GstQuery * query)
1632 GstElementClass *oclass;
1633 gboolean result = FALSE;
1635 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1636 g_return_val_if_fail (query != NULL, FALSE);
1638 oclass = GST_ELEMENT_GET_CLASS (element);
1640 if (oclass->query) {
1641 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1642 GST_ELEMENT_NAME (element));
1643 result = oclass->query (element, query);
1649 * gst_element_post_message:
1650 * @element: a #GstElement posting the message
1651 * @message: (transfer full): a #GstMessage to post
1653 * Post a message on the element's #GstBus. This function takes ownership of the
1654 * message; if you want to access the message after this call, you should add an
1655 * additional reference before calling.
1657 * Returns: %TRUE if the message was successfully posted. The function returns
1658 * %FALSE if the element did not have a bus.
1663 gst_element_post_message (GstElement * element, GstMessage * message)
1666 gboolean result = FALSE;
1668 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1669 g_return_val_if_fail (message != NULL, FALSE);
1671 GST_OBJECT_LOCK (element);
1674 if (G_UNLIKELY (bus == NULL))
1677 gst_object_ref (bus);
1678 GST_OBJECT_UNLOCK (element);
1680 /* we release the element lock when posting the message so that any
1681 * (synchronous) message handlers can operate on the element */
1682 result = gst_bus_post (bus, message);
1683 gst_object_unref (bus);
1690 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1691 "not posting message %p: no bus", message);
1692 GST_OBJECT_UNLOCK (element);
1693 gst_message_unref (message);
1699 * _gst_element_error_printf:
1700 * @format: the printf-like format to use, or %NULL
1702 * This function is only used internally by the gst_element_error() macro.
1704 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1710 _gst_element_error_printf (const gchar * format, ...)
1720 va_start (args, format);
1721 buffer = g_strdup_vprintf (format, args);
1727 * gst_element_message_full:
1728 * @element: a #GstElement to send message from
1729 * @type: the #GstMessageType
1730 * @domain: the GStreamer GError domain this message belongs to
1731 * @code: the GError code belonging to the domain
1732 * @text: (allow-none) (transfer full): an allocated text string to be used
1733 * as a replacement for the default message connected to code,
1735 * @debug: (allow-none) (transfer full): an allocated debug message to be
1736 * used as a replacement for the default debugging information,
1738 * @file: the source code file where the error was generated
1739 * @function: the source code function where the error was generated
1740 * @line: the source code line where the error was generated
1742 * Post an error, warning or info message on the bus from inside an element.
1744 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1745 * #GST_MESSAGE_INFO.
1749 void gst_element_message_full
1750 (GstElement * element, GstMessageType type,
1751 GQuark domain, gint code, gchar * text,
1752 gchar * debug, const gchar * file, const gchar * function, gint line)
1754 GError *gerror = NULL;
1758 gboolean has_debug = TRUE;
1759 GstMessage *message = NULL;
1762 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1763 g_return_if_fail (GST_IS_ELEMENT (element));
1764 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1765 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1767 /* check if we send the given text or the default error text */
1768 if ((text == NULL) || (text[0] == 0)) {
1769 /* text could have come from g_strdup_printf (""); */
1771 sent_text = gst_error_get_message (domain, code);
1775 /* construct a sent_debug with extra information from source */
1776 if ((debug == NULL) || (debug[0] == 0)) {
1777 /* debug could have come from g_strdup_printf (""); */
1781 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1783 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1784 file, line, function, name, debug);
1786 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1787 file, line, function, name);
1791 /* create gerror and post message */
1792 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1794 gerror = g_error_new_literal (domain, code, sent_text);
1797 case GST_MESSAGE_ERROR:
1799 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1801 case GST_MESSAGE_WARNING:
1802 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1805 case GST_MESSAGE_INFO:
1806 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1810 g_assert_not_reached ();
1813 gst_element_post_message (element, message);
1815 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1816 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1819 g_error_free (gerror);
1820 g_free (sent_debug);
1825 * gst_element_is_locked_state:
1826 * @element: a #GstElement.
1828 * Checks if the state of an element is locked.
1829 * If the state of an element is locked, state changes of the parent don't
1830 * affect the element.
1831 * This way you can leave currently unused elements inside bins. Just lock their
1832 * state before changing the state from #GST_STATE_NULL.
1836 * Returns: TRUE, if the element's state is locked.
1839 gst_element_is_locked_state (GstElement * element)
1843 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1845 GST_OBJECT_LOCK (element);
1846 result = GST_ELEMENT_IS_LOCKED_STATE (element);
1847 GST_OBJECT_UNLOCK (element);
1853 * gst_element_set_locked_state:
1854 * @element: a #GstElement
1855 * @locked_state: TRUE to lock the element's state
1857 * Locks the state of an element, so state changes of the parent don't affect
1858 * this element anymore.
1862 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1863 * or the elements state-locking needed no change.
1866 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1870 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1872 GST_OBJECT_LOCK (element);
1873 old = GST_ELEMENT_IS_LOCKED_STATE (element);
1875 if (G_UNLIKELY (old == locked_state))
1879 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1880 GST_ELEMENT_NAME (element));
1881 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1883 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1884 GST_ELEMENT_NAME (element));
1885 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1887 GST_OBJECT_UNLOCK (element);
1893 GST_CAT_DEBUG (GST_CAT_STATES,
1894 "elements %s was already in locked state %d",
1895 GST_ELEMENT_NAME (element), old);
1896 GST_OBJECT_UNLOCK (element);
1903 * gst_element_sync_state_with_parent:
1904 * @element: a #GstElement.
1906 * Tries to change the state of the element to the same as its parent.
1907 * If this function returns FALSE, the state of element is undefined.
1909 * Returns: TRUE, if the element's state could be synced to the parent's state.
1914 gst_element_sync_state_with_parent (GstElement * element)
1918 GstStateChangeReturn ret;
1920 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1922 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1923 GstState parent_current, parent_pending;
1925 GST_OBJECT_LOCK (parent);
1926 parent_current = GST_STATE (parent);
1927 parent_pending = GST_STATE_PENDING (parent);
1928 GST_OBJECT_UNLOCK (parent);
1930 /* set to pending if there is one, else we set it to the current state of
1932 if (parent_pending != GST_STATE_VOID_PENDING)
1933 target = parent_pending;
1935 target = parent_current;
1937 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1938 "syncing state (%s) to parent %s %s (%s, %s)",
1939 gst_element_state_get_name (GST_STATE (element)),
1940 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1941 gst_element_state_get_name (parent_current),
1942 gst_element_state_get_name (parent_pending));
1944 ret = gst_element_set_state (element, target);
1945 if (ret == GST_STATE_CHANGE_FAILURE)
1948 gst_object_unref (parent);
1952 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
1959 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1960 "syncing state failed (%s)",
1961 gst_element_state_change_return_get_name (ret));
1962 gst_object_unref (parent);
1968 static GstStateChangeReturn
1969 gst_element_get_state_func (GstElement * element,
1970 GstState * state, GstState * pending, GstClockTime timeout)
1972 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
1973 GstState old_pending;
1975 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
1976 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
1978 GST_OBJECT_LOCK (element);
1979 ret = GST_STATE_RETURN (element);
1980 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
1981 gst_element_state_change_return_get_name (ret));
1983 /* we got an error, report immediately */
1984 if (ret == GST_STATE_CHANGE_FAILURE)
1987 /* we got no_preroll, report immediately */
1988 if (ret == GST_STATE_CHANGE_NO_PREROLL)
1991 /* no need to wait async if we are not async */
1992 if (ret != GST_STATE_CHANGE_ASYNC)
1995 old_pending = GST_STATE_PENDING (element);
1996 if (old_pending != GST_STATE_VOID_PENDING) {
2000 /* get cookie to detect state changes during waiting */
2001 cookie = element->state_cookie;
2003 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2004 "waiting for element to commit state");
2006 /* we have a pending state change, wait for it to complete */
2007 if (timeout != GST_CLOCK_TIME_NONE) {
2009 /* make timeout absolute */
2010 end_time = g_get_monotonic_time () + (timeout / 1000);
2011 signaled = GST_STATE_WAIT_UNTIL (element, end_time);
2013 GST_STATE_WAIT (element);
2018 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2019 /* timeout triggered */
2020 ret = GST_STATE_CHANGE_ASYNC;
2022 if (cookie != element->state_cookie)
2025 /* could be success or failure */
2026 if (old_pending == GST_STATE (element)) {
2027 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2028 ret = GST_STATE_CHANGE_SUCCESS;
2030 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2031 ret = GST_STATE_CHANGE_FAILURE;
2034 /* if nothing is pending anymore we can return SUCCESS */
2035 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2036 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2037 ret = GST_STATE_CHANGE_SUCCESS;
2043 *state = GST_STATE (element);
2045 *pending = GST_STATE_PENDING (element);
2047 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2048 "state current: %s, pending: %s, result: %s",
2049 gst_element_state_get_name (GST_STATE (element)),
2050 gst_element_state_get_name (GST_STATE_PENDING (element)),
2051 gst_element_state_change_return_get_name (ret));
2052 GST_OBJECT_UNLOCK (element);
2059 *state = GST_STATE_VOID_PENDING;
2061 *pending = GST_STATE_VOID_PENDING;
2063 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2065 GST_OBJECT_UNLOCK (element);
2067 return GST_STATE_CHANGE_FAILURE;
2072 * gst_element_get_state:
2073 * @element: a #GstElement to get the state of.
2074 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2076 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2077 * state. Can be %NULL.
2078 * @timeout: a #GstClockTime to specify the timeout for an async
2079 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2081 * Gets the state of the element.
2083 * For elements that performed an ASYNC state change, as reported by
2084 * gst_element_set_state(), this function will block up to the
2085 * specified timeout value for the state change to complete.
2086 * If the element completes the state change or goes into
2087 * an error, this function returns immediately with a return value of
2088 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2090 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2091 * returns the current and pending state immediately.
2093 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2094 * successfully changed its state but is not able to provide data yet.
2095 * This mostly happens for live sources that only produce data in
2096 * %GST_STATE_PLAYING. While the state change return is equivalent to
2097 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2098 * some sink elements might not be able to complete their state change because
2099 * an element is not producing data to complete the preroll. When setting the
2100 * element to playing, the preroll will complete and playback will start.
2102 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2103 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2104 * element is still performing a state change or
2105 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2109 GstStateChangeReturn
2110 gst_element_get_state (GstElement * element,
2111 GstState * state, GstState * pending, GstClockTime timeout)
2113 GstElementClass *oclass;
2114 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2116 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2118 oclass = GST_ELEMENT_GET_CLASS (element);
2120 if (oclass->get_state)
2121 result = (oclass->get_state) (element, state, pending, timeout);
2127 * gst_element_abort_state:
2128 * @element: a #GstElement to abort the state of.
2130 * Abort the state change of the element. This function is used
2131 * by elements that do asynchronous state changes and find out
2132 * something is wrong.
2134 * This function should be called with the STATE_LOCK held.
2139 gst_element_abort_state (GstElement * element)
2143 #ifndef GST_DISABLE_GST_DEBUG
2147 g_return_if_fail (GST_IS_ELEMENT (element));
2149 GST_OBJECT_LOCK (element);
2150 pending = GST_STATE_PENDING (element);
2152 if (pending == GST_STATE_VOID_PENDING ||
2153 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2154 goto nothing_aborted;
2156 #ifndef GST_DISABLE_GST_DEBUG
2157 old_state = GST_STATE (element);
2159 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2160 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2161 gst_element_state_get_name (pending));
2165 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2167 GST_STATE_BROADCAST (element);
2168 GST_OBJECT_UNLOCK (element);
2174 GST_OBJECT_UNLOCK (element);
2179 /* Not static because GstBin has manual state handling too */
2181 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2182 GstState newstate, GstState pending)
2184 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2185 GstMessage *message;
2187 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2188 "notifying about state-changed %s to %s (%s pending)",
2189 gst_element_state_get_name (oldstate),
2190 gst_element_state_get_name (newstate),
2191 gst_element_state_get_name (pending));
2193 if (klass->state_changed)
2194 klass->state_changed (element, oldstate, newstate, pending);
2196 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2197 oldstate, newstate, pending);
2198 gst_element_post_message (element, message);
2202 * gst_element_continue_state:
2203 * @element: a #GstElement to continue the state change of.
2204 * @ret: The previous state return value
2206 * Commit the state change of the element and proceed to the next
2207 * pending state if any. This function is used
2208 * by elements that do asynchronous state changes.
2209 * The core will normally call this method automatically when an
2210 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2212 * If after calling this method the element still has not reached
2213 * the pending state, the next state change is performed.
2215 * This method is used internally and should normally not be called by plugins
2218 * Returns: The result of the commit state change.
2222 GstStateChangeReturn
2223 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2225 GstStateChangeReturn old_ret;
2226 GstState old_state, old_next;
2227 GstState current, next, pending;
2228 GstStateChange transition;
2230 GST_OBJECT_LOCK (element);
2231 old_ret = GST_STATE_RETURN (element);
2232 GST_STATE_RETURN (element) = ret;
2233 pending = GST_STATE_PENDING (element);
2235 /* check if there is something to commit */
2236 if (pending == GST_STATE_VOID_PENDING)
2237 goto nothing_pending;
2239 old_state = GST_STATE (element);
2240 /* this is the state we should go to next */
2241 old_next = GST_STATE_NEXT (element);
2242 /* update current state */
2243 current = GST_STATE (element) = old_next;
2245 /* see if we reached the final state */
2246 if (pending == current)
2249 next = GST_STATE_GET_NEXT (current, pending);
2250 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2252 GST_STATE_NEXT (element) = next;
2254 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2255 GST_OBJECT_UNLOCK (element);
2257 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2258 "committing state from %s to %s, pending %s, next %s",
2259 gst_element_state_get_name (old_state),
2260 gst_element_state_get_name (old_next),
2261 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2263 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2265 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2266 "continue state change %s to %s, final %s",
2267 gst_element_state_get_name (current),
2268 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2270 ret = gst_element_change_state (element, transition);
2276 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2277 GST_OBJECT_UNLOCK (element);
2282 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2283 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2285 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2286 "completed state change to %s", gst_element_state_get_name (pending));
2287 GST_OBJECT_UNLOCK (element);
2289 /* don't post silly messages with the same state. This can happen
2290 * when an element state is changed to what it already was. For bins
2291 * this can be the result of a lost state, which we check with the
2292 * previous return value.
2293 * We do signal the cond though as a _get_state() might be blocking
2295 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2296 _priv_gst_element_state_changed (element, old_state, old_next,
2297 GST_STATE_VOID_PENDING);
2299 GST_STATE_BROADCAST (element);
2306 * gst_element_lost_state:
2307 * @element: a #GstElement the state is lost of
2309 * Brings the element to the lost state. The current state of the
2310 * element is copied to the pending state so that any call to
2311 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2313 * An ASYNC_START message is posted. If the element was PLAYING, it will
2314 * go to PAUSED. The element will be restored to its PLAYING state by
2315 * the parent pipeline when it prerolls again.
2317 * This is mostly used for elements that lost their preroll buffer
2318 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2319 * they will go to their pending state again when a new preroll buffer is
2320 * queued. This function can only be called when the element is currently
2321 * not in error or an async state change.
2323 * This function is used internally and should normally not be called from
2324 * plugins or applications.
2327 gst_element_lost_state (GstElement * element)
2329 GstState old_state, new_state;
2330 GstMessage *message;
2332 g_return_if_fail (GST_IS_ELEMENT (element));
2334 GST_OBJECT_LOCK (element);
2335 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2338 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2339 goto only_async_start;
2341 old_state = GST_STATE (element);
2343 /* when we were PLAYING, the new state is PAUSED. We will also not
2344 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2345 * when we preroll. */
2346 if (old_state > GST_STATE_PAUSED)
2347 new_state = GST_STATE_PAUSED;
2349 new_state = old_state;
2351 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2352 "lost state of %s to %s", gst_element_state_get_name (old_state),
2353 gst_element_state_get_name (new_state));
2355 GST_STATE (element) = new_state;
2356 GST_STATE_NEXT (element) = new_state;
2357 GST_STATE_PENDING (element) = new_state;
2358 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2359 GST_OBJECT_UNLOCK (element);
2361 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2363 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2364 gst_element_post_message (element, message);
2370 GST_OBJECT_UNLOCK (element);
2375 GST_OBJECT_UNLOCK (element);
2377 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2378 gst_element_post_message (element, message);
2384 * gst_element_set_state:
2385 * @element: a #GstElement to change state of.
2386 * @state: the element's new #GstState.
2388 * Sets the state of the element. This function will try to set the
2389 * requested state by going through all the intermediary states and calling
2390 * the class's state change function for each.
2392 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2393 * element will perform the remainder of the state change asynchronously in
2395 * An application can use gst_element_get_state() to wait for the completion
2396 * of the state change or it can wait for a state change message on the bus.
2398 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2399 * #GST_STATE_CHANGE_ASYNC.
2401 * Returns: Result of the state change using #GstStateChangeReturn.
2405 GstStateChangeReturn
2406 gst_element_set_state (GstElement * element, GstState state)
2408 GstElementClass *oclass;
2409 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2411 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2413 oclass = GST_ELEMENT_GET_CLASS (element);
2415 if (oclass->set_state)
2416 result = (oclass->set_state) (element, state);
2422 * default set state function, calculates the next state based
2423 * on current state and calls the change_state function
2425 static GstStateChangeReturn
2426 gst_element_set_state_func (GstElement * element, GstState state)
2428 GstState current, next, old_pending;
2429 GstStateChangeReturn ret;
2430 GstStateChange transition;
2431 GstStateChangeReturn old_ret;
2433 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2435 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2436 gst_element_state_get_name (state));
2438 /* state lock is taken to protect the set_state() and get_state()
2439 * procedures, it does not lock any variables. */
2440 GST_STATE_LOCK (element);
2442 /* now calculate how to get to the new state */
2443 GST_OBJECT_LOCK (element);
2444 old_ret = GST_STATE_RETURN (element);
2445 /* previous state change returned an error, remove all pending
2446 * and next states */
2447 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2448 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2449 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2450 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2453 current = GST_STATE (element);
2454 next = GST_STATE_NEXT (element);
2455 old_pending = GST_STATE_PENDING (element);
2457 /* this is the (new) state we should go to. TARGET is the last state we set on
2459 if (state != GST_STATE_TARGET (element)) {
2460 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2461 "setting target state to %s", gst_element_state_get_name (state));
2462 GST_STATE_TARGET (element) = state;
2463 /* increment state cookie so that we can track each state change. We only do
2464 * this if this is actually a new state change. */
2465 element->state_cookie++;
2467 GST_STATE_PENDING (element) = state;
2469 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2470 "current %s, old_pending %s, next %s, old return %s",
2471 gst_element_state_get_name (current),
2472 gst_element_state_get_name (old_pending),
2473 gst_element_state_get_name (next),
2474 gst_element_state_change_return_get_name (old_ret));
2476 /* if the element was busy doing a state change, we just update the
2477 * target state, it'll get to it async then. */
2478 if (old_pending != GST_STATE_VOID_PENDING) {
2479 /* upwards state change will happen ASYNC */
2480 if (old_pending <= state)
2482 /* element is going to this state already */
2483 else if (next == state)
2485 /* element was performing an ASYNC upward state change and
2486 * we request to go downward again. Start from the next pending
2488 else if (next > state
2489 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2493 next = GST_STATE_GET_NEXT (current, state);
2494 /* now we store the next state */
2495 GST_STATE_NEXT (element) = next;
2496 /* mark busy, we need to check that there is actually a state change
2497 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2498 * the default element change_state function has no way to know what the
2499 * old value was... could consider this a FIXME...*/
2500 if (current != next)
2501 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2503 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2505 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2506 "%s: setting state from %s to %s",
2507 (next != state ? "intermediate" : "final"),
2508 gst_element_state_get_name (current), gst_element_state_get_name (next));
2510 /* now signal any waiters, they will error since the cookie was incremented */
2511 GST_STATE_BROADCAST (element);
2513 GST_OBJECT_UNLOCK (element);
2515 ret = gst_element_change_state (element, transition);
2517 GST_STATE_UNLOCK (element);
2519 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2520 gst_element_state_change_return_get_name (ret));
2526 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2527 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2528 "element was busy with async state change");
2529 GST_OBJECT_UNLOCK (element);
2531 GST_STATE_UNLOCK (element);
2533 return GST_STATE_CHANGE_ASYNC;
2538 * gst_element_change_state:
2539 * @element: a #GstElement
2540 * @transition: the requested transition
2542 * Perform @transition on @element.
2544 * This function must be called with STATE_LOCK held and is mainly used
2547 * Returns: the #GstStateChangeReturn of the state transition.
2549 GstStateChangeReturn
2550 gst_element_change_state (GstElement * element, GstStateChange transition)
2552 GstElementClass *oclass;
2553 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2555 oclass = GST_ELEMENT_GET_CLASS (element);
2557 /* call the state change function so it can set the state */
2558 if (oclass->change_state)
2559 ret = (oclass->change_state) (element, transition);
2561 ret = GST_STATE_CHANGE_FAILURE;
2564 case GST_STATE_CHANGE_FAILURE:
2565 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2566 "have FAILURE change_state return");
2567 /* state change failure */
2568 gst_element_abort_state (element);
2570 case GST_STATE_CHANGE_ASYNC:
2574 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2575 "element will change state ASYNC");
2577 target = GST_STATE_TARGET (element);
2579 if (target > GST_STATE_READY)
2582 /* else we just continue the state change downwards */
2583 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2584 "forcing commit state %s <= %s",
2585 gst_element_state_get_name (target),
2586 gst_element_state_get_name (GST_STATE_READY));
2588 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2591 case GST_STATE_CHANGE_SUCCESS:
2592 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2593 "element changed state SUCCESS");
2594 /* we can commit the state now which will proceeed to
2596 ret = gst_element_continue_state (element, ret);
2598 case GST_STATE_CHANGE_NO_PREROLL:
2599 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2600 "element changed state NO_PREROLL");
2601 /* we can commit the state now which will proceeed to
2603 ret = gst_element_continue_state (element, ret);
2606 goto invalid_return;
2609 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2614 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2622 GST_OBJECT_LOCK (element);
2623 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2624 g_critical ("%s: unknown return value %d from a state change function",
2625 GST_ELEMENT_NAME (element), ret);
2627 /* we are in error now */
2628 ret = GST_STATE_CHANGE_FAILURE;
2629 GST_STATE_RETURN (element) = ret;
2630 GST_OBJECT_UNLOCK (element);
2636 /* gst_iterator_fold functions for pads_activate
2637 * Stop the iterator if activating one pad failed. */
2639 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2641 GstPad *pad = g_value_get_object (vpad);
2642 gboolean cont = TRUE;
2644 if (!(cont = gst_pad_set_active (pad, *active)))
2645 g_value_set_boolean (ret, FALSE);
2650 /* returns false on error or early cutout of the fold, true if all
2651 * pads in @iter were (de)activated successfully. */
2653 iterator_activate_fold_with_resync (GstIterator * iter,
2654 GstIteratorFoldFunction func, gpointer user_data)
2656 GstIteratorResult ires;
2659 /* no need to unset this later, it's just a boolean */
2660 g_value_init (&ret, G_TYPE_BOOLEAN);
2661 g_value_set_boolean (&ret, TRUE);
2664 ires = gst_iterator_fold (iter, func, &ret, user_data);
2666 case GST_ITERATOR_RESYNC:
2667 /* need to reset the result again */
2668 g_value_set_boolean (&ret, TRUE);
2669 gst_iterator_resync (iter);
2671 case GST_ITERATOR_DONE:
2672 /* all pads iterated, return collected value */
2675 /* iterator returned _ERROR or premature end with _OK,
2676 * mark an error and exit */
2677 g_value_set_boolean (&ret, FALSE);
2682 /* return collected value */
2683 return g_value_get_boolean (&ret);
2686 /* is called with STATE_LOCK
2688 * Pads are activated from source pads to sinkpads.
2691 gst_element_pads_activate (GstElement * element, gboolean active)
2696 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2697 "pads_activate with active %d", active);
2699 iter = gst_element_iterate_src_pads (element);
2701 iterator_activate_fold_with_resync (iter,
2702 (GstIteratorFoldFunction) activate_pads, &active);
2703 gst_iterator_free (iter);
2704 if (G_UNLIKELY (!res))
2707 iter = gst_element_iterate_sink_pads (element);
2709 iterator_activate_fold_with_resync (iter,
2710 (GstIteratorFoldFunction) activate_pads, &active);
2711 gst_iterator_free (iter);
2712 if (G_UNLIKELY (!res))
2715 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2716 "pads_activate successful");
2723 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2724 "source pads_activate failed");
2729 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2730 "sink pads_activate failed");
2735 /* is called with STATE_LOCK */
2736 static GstStateChangeReturn
2737 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2739 GstState state, next;
2740 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2742 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2744 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2745 next = GST_STATE_TRANSITION_NEXT (transition);
2747 /* if the element already is in the given state, we just return success */
2748 if (next == GST_STATE_VOID_PENDING || state == next)
2751 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2752 "default handler tries setting state from %s to %s (%04x)",
2753 gst_element_state_get_name (state),
2754 gst_element_state_get_name (next), transition);
2756 switch (transition) {
2757 case GST_STATE_CHANGE_NULL_TO_READY:
2759 case GST_STATE_CHANGE_READY_TO_PAUSED:
2760 if (!gst_element_pads_activate (element, TRUE)) {
2761 result = GST_STATE_CHANGE_FAILURE;
2764 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2766 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2768 case GST_STATE_CHANGE_PAUSED_TO_READY:
2769 case GST_STATE_CHANGE_READY_TO_NULL:
2770 /* deactivate pads in both cases, since they are activated on
2771 ready->paused but the element might not have made it to paused */
2772 if (!gst_element_pads_activate (element, FALSE)) {
2773 result = GST_STATE_CHANGE_FAILURE;
2777 /* this will catch real but unhandled state changes;
2778 * can only be caused by:
2779 * - a new state was added
2780 * - somehow the element was asked to jump across an intermediate state
2782 g_warning ("Unhandled state change from %s to %s",
2783 gst_element_state_get_name (state),
2784 gst_element_state_get_name (next));
2791 GST_OBJECT_LOCK (element);
2792 result = GST_STATE_RETURN (element);
2793 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2794 "element is already in the %s state",
2795 gst_element_state_get_name (state));
2796 GST_OBJECT_UNLOCK (element);
2803 * gst_element_get_factory:
2804 * @element: a #GstElement to request the element factory of.
2806 * Retrieves the factory that was used to create this element.
2808 * Returns: (transfer none): the #GstElementFactory used for creating this
2809 * element. no refcounting is needed.
2812 gst_element_get_factory (GstElement * element)
2814 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2816 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2820 gst_element_dispose (GObject * object)
2822 GstElement *element = GST_ELEMENT_CAST (object);
2825 GstElementClass *oclass;
2827 oclass = GST_ELEMENT_GET_CLASS (element);
2829 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2831 if (GST_STATE (element) != GST_STATE_NULL)
2834 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2835 "removing %d pads", g_list_length (element->pads));
2836 /* first we break all our links with the outside */
2837 while (element->pads && element->pads->data) {
2838 GstPad *pad = GST_PAD_CAST (element->pads->data);
2840 /* don't call _remove_pad with NULL */
2841 if (oclass->release_pad && GST_PAD_PAD_TEMPLATE (pad) &&
2842 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
2844 (oclass->release_pad) (element, GST_PAD_CAST (element->pads->data));
2846 gst_element_remove_pad (element, GST_PAD_CAST (element->pads->data));
2848 if (G_UNLIKELY (element->pads != NULL)) {
2849 g_critical ("could not remove pads from element %s",
2850 GST_STR_NULL (GST_OBJECT_NAME (object)));
2853 GST_OBJECT_LOCK (element);
2854 clock_p = &element->clock;
2855 bus_p = &element->bus;
2856 gst_object_replace ((GstObject **) clock_p, NULL);
2857 gst_object_replace ((GstObject **) bus_p, NULL);
2858 GST_OBJECT_UNLOCK (element);
2860 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2862 G_OBJECT_CLASS (parent_class)->dispose (object);
2871 is_locked = GST_ELEMENT_IS_LOCKED_STATE (element);
2873 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2875 "You need to explicitly set elements to the NULL state before\n"
2876 "dropping the final reference, to allow them to clean up.\n"
2877 "This problem may also be caused by a refcounting bug in the\n"
2878 "application or some element.\n",
2879 GST_OBJECT_NAME (element),
2880 gst_element_state_get_name (GST_STATE (element)),
2881 is_locked ? " (locked)" : "");
2887 gst_element_finalize (GObject * object)
2889 GstElement *element = GST_ELEMENT_CAST (object);
2891 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2893 g_cond_clear (&element->state_cond);
2894 g_rec_mutex_clear (&element->state_lock);
2896 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2898 G_OBJECT_CLASS (parent_class)->finalize (object);
2902 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2906 g_return_if_fail (GST_IS_ELEMENT (element));
2908 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2910 GST_OBJECT_LOCK (element);
2911 bus_p = &GST_ELEMENT_BUS (element);
2912 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
2913 GST_OBJECT_UNLOCK (element);
2917 * gst_element_set_bus:
2918 * @element: a #GstElement to set the bus of.
2919 * @bus: (transfer none): the #GstBus to set.
2921 * Sets the bus of the element. Increases the refcount on the bus.
2922 * For internal use only, unless you're testing elements.
2927 gst_element_set_bus (GstElement * element, GstBus * bus)
2929 GstElementClass *oclass;
2931 g_return_if_fail (GST_IS_ELEMENT (element));
2933 oclass = GST_ELEMENT_GET_CLASS (element);
2935 if (oclass->set_bus)
2936 oclass->set_bus (element, bus);
2940 * gst_element_get_bus:
2941 * @element: a #GstElement to get the bus of.
2943 * Returns the bus of the element. Note that only a #GstPipeline will provide a
2944 * bus for the application.
2946 * Returns: (transfer full): the element's #GstBus. unref after usage.
2951 gst_element_get_bus (GstElement * element)
2953 GstBus *result = NULL;
2955 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
2957 GST_OBJECT_LOCK (element);
2958 if ((result = GST_ELEMENT_BUS (element)))
2959 gst_object_ref (result);
2960 GST_OBJECT_UNLOCK (element);
2962 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,