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"
97 #include "gst-i18n-lib.h"
98 #include "glib-compat-private.h"
100 /* Element signals and args */
116 static void gst_element_class_init (GstElementClass * klass);
117 static void gst_element_init (GstElement * element);
118 static void gst_element_base_class_init (gpointer g_class);
119 static void gst_element_base_class_finalize (gpointer g_class);
121 static void gst_element_dispose (GObject * object);
122 static void gst_element_finalize (GObject * object);
124 static GstStateChangeReturn gst_element_change_state_func (GstElement * element,
125 GstStateChange transition);
126 static GstStateChangeReturn gst_element_get_state_func (GstElement * element,
127 GstState * state, GstState * pending, GstClockTime timeout);
128 static GstStateChangeReturn gst_element_set_state_func (GstElement * element,
130 static gboolean gst_element_set_clock_func (GstElement * element,
132 static void gst_element_set_bus_func (GstElement * element, GstBus * bus);
134 static gboolean gst_element_default_send_event (GstElement * element,
136 static gboolean gst_element_default_query (GstElement * element,
139 static GstPadTemplate
140 * gst_element_class_get_request_pad_template (GstElementClass *
141 element_class, const gchar * name);
143 static GstObjectClass *parent_class = NULL;
144 static guint gst_element_signals[LAST_SIGNAL] = { 0 };
146 /* this is used in gstelementfactory.c:gst_element_register() */
147 GQuark __gst_elementclass_factory = 0;
150 gst_element_get_type (void)
152 static volatile gsize gst_element_type = 0;
154 if (g_once_init_enter (&gst_element_type)) {
156 static const GTypeInfo element_info = {
157 sizeof (GstElementClass),
158 gst_element_base_class_init,
159 gst_element_base_class_finalize,
160 (GClassInitFunc) gst_element_class_init,
165 (GInstanceInitFunc) gst_element_init,
169 _type = g_type_register_static (GST_TYPE_OBJECT, "GstElement",
170 &element_info, G_TYPE_FLAG_ABSTRACT);
172 __gst_elementclass_factory =
173 g_quark_from_static_string ("GST_ELEMENTCLASS_FACTORY");
174 g_once_init_leave (&gst_element_type, _type);
176 return gst_element_type;
180 gst_element_class_init (GstElementClass * klass)
182 GObjectClass *gobject_class;
184 gobject_class = (GObjectClass *) klass;
186 parent_class = g_type_class_peek_parent (klass);
189 * GstElement::pad-added:
190 * @gstelement: the object which received the signal
191 * @new_pad: the pad that has been added
193 * a new #GstPad has been added to the element. Note that this signal will
194 * usually be emitted from the context of the streaming thread. Also keep in
195 * mind that if you add new elements to the pipeline in the signal handler
196 * you will need to set them to the desired target state with
197 * gst_element_set_state() or gst_element_sync_state_with_parent().
199 gst_element_signals[PAD_ADDED] =
200 g_signal_new ("pad-added", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
201 G_STRUCT_OFFSET (GstElementClass, pad_added), NULL, NULL,
202 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
204 * GstElement::pad-removed:
205 * @gstelement: the object which received the signal
206 * @old_pad: the pad that has been removed
208 * a #GstPad has been removed from the element
210 gst_element_signals[PAD_REMOVED] =
211 g_signal_new ("pad-removed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
212 G_STRUCT_OFFSET (GstElementClass, pad_removed), NULL, NULL,
213 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
215 * GstElement::no-more-pads:
216 * @gstelement: the object which received the signal
218 * This signals that the element will not generate more dynamic pads.
219 * Note that this signal will usually be emitted from the context of
220 * the streaming thread.
222 gst_element_signals[NO_MORE_PADS] =
223 g_signal_new ("no-more-pads", G_TYPE_FROM_CLASS (klass),
224 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstElementClass, no_more_pads), NULL,
225 NULL, g_cclosure_marshal_generic, G_TYPE_NONE, 0);
227 gobject_class->dispose = gst_element_dispose;
228 gobject_class->finalize = gst_element_finalize;
230 klass->change_state = GST_DEBUG_FUNCPTR (gst_element_change_state_func);
231 klass->set_state = GST_DEBUG_FUNCPTR (gst_element_set_state_func);
232 klass->get_state = GST_DEBUG_FUNCPTR (gst_element_get_state_func);
233 klass->set_clock = GST_DEBUG_FUNCPTR (gst_element_set_clock_func);
234 klass->set_bus = GST_DEBUG_FUNCPTR (gst_element_set_bus_func);
235 klass->query = GST_DEBUG_FUNCPTR (gst_element_default_query);
236 klass->send_event = GST_DEBUG_FUNCPTR (gst_element_default_send_event);
237 klass->numpadtemplates = 0;
239 klass->elementfactory = NULL;
243 gst_element_base_class_init (gpointer g_class)
245 GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
246 GList *node, *padtemplates;
248 /* Copy the element details here so elements can inherit the
249 * details from their base class and classes only need to set
250 * the details in class_init instead of base_init */
251 element_class->metadata =
252 element_class->metadata ? gst_structure_copy (element_class->metadata) :
253 gst_structure_new_empty ("metadata");
255 /* Copy the pad templates so elements inherit them
256 * from their base class but elements can add pad templates in class_init
257 * instead of base_init.
259 padtemplates = g_list_copy (element_class->padtemplates);
260 for (node = padtemplates; node != NULL; node = node->next) {
261 GstPadTemplate *tmpl = (GstPadTemplate *) node->data;
262 gst_object_ref (tmpl);
264 element_class->padtemplates = padtemplates;
266 /* set the factory, see gst_element_register() */
267 element_class->elementfactory =
268 g_type_get_qdata (G_TYPE_FROM_CLASS (element_class),
269 __gst_elementclass_factory);
270 GST_DEBUG ("type %s : factory %p", G_OBJECT_CLASS_NAME (element_class),
271 element_class->elementfactory);
275 gst_element_base_class_finalize (gpointer g_class)
277 GstElementClass *klass = GST_ELEMENT_CLASS (g_class);
279 g_list_foreach (klass->padtemplates, (GFunc) gst_object_unref, NULL);
280 g_list_free (klass->padtemplates);
282 gst_structure_free (klass->metadata);
286 gst_element_init (GstElement * element)
288 GST_STATE (element) = GST_STATE_NULL;
289 GST_STATE_TARGET (element) = GST_STATE_NULL;
290 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
291 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
292 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
294 g_rec_mutex_init (&element->state_lock);
295 g_cond_init (&element->state_cond);
299 * gst_element_release_request_pad:
300 * @element: a #GstElement to release the request pad of.
301 * @pad: the #GstPad to release.
303 * Makes the element free the previously requested pad as obtained
304 * with gst_element_get_request_pad().
306 * This does not unref the pad. If the pad was created by using
307 * gst_element_get_request_pad(), gst_element_release_request_pad() needs to be
308 * followed by gst_object_unref() to free the @pad.
313 gst_element_release_request_pad (GstElement * element, GstPad * pad)
315 GstElementClass *oclass;
317 g_return_if_fail (GST_IS_ELEMENT (element));
318 g_return_if_fail (GST_IS_PAD (pad));
319 g_return_if_fail (GST_PAD_PAD_TEMPLATE (pad) == NULL ||
320 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad)) ==
323 oclass = GST_ELEMENT_GET_CLASS (element);
325 /* if the element implements a custom release function we call that, else we
326 * simply remove the pad from the element */
327 if (oclass->release_pad)
328 (oclass->release_pad) (element, pad);
330 gst_element_remove_pad (element, pad);
334 * gst_element_provide_clock:
335 * @element: a #GstElement to query
337 * Get the clock provided by the given element.
338 * <note>An element is only required to provide a clock in the PAUSED
339 * state. Some elements can provide a clock in other states.</note>
341 * Returns: (transfer full): the GstClock provided by the element or %NULL
342 * if no clock could be provided. Unref after usage.
347 gst_element_provide_clock (GstElement * element)
349 GstClock *result = NULL;
350 GstElementClass *oclass;
352 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
354 oclass = GST_ELEMENT_GET_CLASS (element);
356 if (oclass->provide_clock)
357 result = oclass->provide_clock (element);
363 gst_element_set_clock_func (GstElement * element, GstClock * clock)
367 GST_OBJECT_LOCK (element);
368 clock_p = &element->clock;
369 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
370 GST_OBJECT_UNLOCK (element);
376 * gst_element_set_clock:
377 * @element: a #GstElement to set the clock for.
378 * @clock: the #GstClock to set for the element.
380 * Sets the clock for the element. This function increases the
381 * refcount on the clock. Any previously set clock on the object
384 * Returns: %TRUE if the element accepted the clock. An element can refuse a
385 * clock when it, for example, is not able to slave its internal clock to the
386 * @clock or when it requires a specific clock to operate.
391 gst_element_set_clock (GstElement * element, GstClock * clock)
393 GstElementClass *oclass;
394 gboolean res = FALSE;
396 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
397 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
399 oclass = GST_ELEMENT_GET_CLASS (element);
401 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
403 if (oclass->set_clock)
404 res = oclass->set_clock (element, clock);
410 * gst_element_get_clock:
411 * @element: a #GstElement to get the clock of.
413 * Gets the currently configured clock of the element. This is the clock as was
414 * last set with gst_element_set_clock().
416 * Returns: (transfer full): the #GstClock of the element. unref after usage.
421 gst_element_get_clock (GstElement * element)
425 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
427 GST_OBJECT_LOCK (element);
428 if ((result = element->clock))
429 gst_object_ref (result);
430 GST_OBJECT_UNLOCK (element);
436 * gst_element_set_base_time:
437 * @element: a #GstElement.
438 * @time: the base time to set.
440 * Set the base time of an element. See gst_element_get_base_time().
445 gst_element_set_base_time (GstElement * element, GstClockTime time)
449 g_return_if_fail (GST_IS_ELEMENT (element));
451 GST_OBJECT_LOCK (element);
452 old = element->base_time;
453 element->base_time = time;
454 GST_OBJECT_UNLOCK (element);
456 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
457 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
458 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
462 * gst_element_get_base_time:
463 * @element: a #GstElement.
465 * Returns the base time of the element. The base time is the
466 * absolute time of the clock when this element was last put to
467 * PLAYING. Subtracting the base time from the clock time gives
468 * the running time of the element.
470 * Returns: the base time of the element.
475 gst_element_get_base_time (GstElement * element)
479 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
481 GST_OBJECT_LOCK (element);
482 result = element->base_time;
483 GST_OBJECT_UNLOCK (element);
489 * gst_element_set_start_time:
490 * @element: a #GstElement.
491 * @time: the base time to set.
493 * Set the start time of an element. The start time of the element is the
494 * running time of the element when it last went to the PAUSED state. In READY
495 * or after a flushing seek, it is set to 0.
497 * Toplevel elements like #GstPipeline will manage the start_time and
498 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
499 * on such a toplevel element will disable the distribution of the base_time to
500 * the children and can be useful if the application manages the base_time
501 * itself, for example if you want to synchronize capture from multiple
502 * pipelines, and you can also ensure that the pipelines have the same clock.
509 gst_element_set_start_time (GstElement * element, GstClockTime time)
513 g_return_if_fail (GST_IS_ELEMENT (element));
515 GST_OBJECT_LOCK (element);
516 old = GST_ELEMENT_START_TIME (element);
517 GST_ELEMENT_START_TIME (element) = time;
518 GST_OBJECT_UNLOCK (element);
520 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
521 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
522 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
526 * gst_element_get_start_time:
527 * @element: a #GstElement.
529 * Returns the start time of the element. The start time is the
530 * running time of the clock when this element was last put to PAUSED.
532 * Usually the start_time is managed by a toplevel element such as
537 * Returns: the start time of the element.
542 gst_element_get_start_time (GstElement * element)
546 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
548 GST_OBJECT_LOCK (element);
549 result = GST_ELEMENT_START_TIME (element);
550 GST_OBJECT_UNLOCK (element);
557 * gst_element_set_index:
558 * @element: a #GstElement.
559 * @index: (transfer none): a #GstIndex.
561 * Set @index on the element. The refcount of the index
562 * will be increased, any previously set index is unreffed.
567 gst_element_set_index (GstElement * element, GstIndex * index)
569 GstElementClass *oclass;
571 g_return_if_fail (GST_IS_ELEMENT (element));
572 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
574 oclass = GST_ELEMENT_GET_CLASS (element);
576 if (oclass->set_index)
577 oclass->set_index (element, index);
581 * gst_element_get_index:
582 * @element: a #GstElement.
584 * Gets the index from the element.
586 * Returns: (transfer full): a #GstIndex or %NULL when no index was set on the
587 * element. unref after usage.
592 gst_element_get_index (GstElement * element)
594 GstElementClass *oclass;
595 GstIndex *result = NULL;
597 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
599 oclass = GST_ELEMENT_GET_CLASS (element);
601 if (oclass->get_index)
602 result = oclass->get_index (element);
609 * gst_element_add_pad:
610 * @element: a #GstElement to add the pad to.
611 * @pad: (transfer full): the #GstPad to add to the element.
613 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
614 * see gst_object_set_parent() for refcounting information.
616 * Pads are not automatically activated so elements should perform the needed
617 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
618 * state. See gst_pad_set_active() for more information about activating pads.
620 * The pad and the element should be unlocked when calling this function.
622 * This function will emit the #GstElement::pad-added signal on the element.
624 * Returns: %TRUE if the pad could be added. This function can fail when
625 * a pad with the same name already existed or the pad already had another
631 gst_element_add_pad (GstElement * element, GstPad * pad)
636 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
637 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
639 /* locking pad to look at the name */
640 GST_OBJECT_LOCK (pad);
641 pad_name = g_strdup (GST_PAD_NAME (pad));
642 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
643 GST_STR_NULL (pad_name));
644 flushing = GST_PAD_IS_FLUSHING (pad);
645 GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_NEED_PARENT);
646 GST_OBJECT_UNLOCK (pad);
648 /* then check to see if there's already a pad by that name here */
649 GST_OBJECT_LOCK (element);
650 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
653 /* try to set the pad's parent */
654 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
655 GST_OBJECT_CAST (element))))
658 /* check for flushing pads */
659 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
660 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
661 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
662 "use gst_pad_set_active(pad,TRUE) before adding it.",
663 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
665 GST_OBJECT_LOCK (pad);
666 GST_PAD_UNSET_FLUSHING (pad);
667 GST_OBJECT_UNLOCK (pad);
672 /* add it to the list */
673 switch (gst_pad_get_direction (pad)) {
675 element->srcpads = g_list_prepend (element->srcpads, pad);
676 element->numsrcpads++;
679 element->sinkpads = g_list_prepend (element->sinkpads, pad);
680 element->numsinkpads++;
685 element->pads = g_list_prepend (element->pads, pad);
687 element->pads_cookie++;
688 GST_OBJECT_UNLOCK (element);
690 /* emit the PAD_ADDED signal */
691 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
698 g_critical ("Padname %s is not unique in element %s, not adding",
699 pad_name, GST_ELEMENT_NAME (element));
700 GST_OBJECT_UNLOCK (element);
707 ("Pad %s already has parent when trying to add to element %s",
708 pad_name, GST_ELEMENT_NAME (element));
709 GST_OBJECT_UNLOCK (element);
715 GST_OBJECT_LOCK (pad);
717 ("Trying to add pad %s to element %s, but it has no direction",
718 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
719 GST_OBJECT_UNLOCK (pad);
720 GST_OBJECT_UNLOCK (element);
726 * gst_element_remove_pad:
727 * @element: a #GstElement to remove pad from.
728 * @pad: (transfer none): the #GstPad to remove from the element.
730 * Removes @pad from @element. @pad will be destroyed if it has not been
731 * referenced elsewhere using gst_object_unparent().
733 * This function is used by plugin developers and should not be used
734 * by applications. Pads that were dynamically requested from elements
735 * with gst_element_get_request_pad() should be released with the
736 * gst_element_release_request_pad() function instead.
738 * Pads are not automatically deactivated so elements should perform the needed
739 * steps to deactivate the pad in case this pad is removed in the PAUSED or
740 * PLAYING state. See gst_pad_set_active() for more information about
743 * The pad and the element should be unlocked when calling this function.
745 * This function will emit the #GstElement::pad-removed signal on the element.
747 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
748 * pad does not belong to the provided element.
753 gst_element_remove_pad (GstElement * element, GstPad * pad)
757 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
758 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
760 /* locking pad to look at the name and parent */
761 GST_OBJECT_LOCK (pad);
762 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
763 GST_STR_NULL (GST_PAD_NAME (pad)));
765 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
767 GST_OBJECT_UNLOCK (pad);
770 if ((peer = gst_pad_get_peer (pad))) {
771 /* window for MT unsafeness, someone else could unlink here
772 * and then we call unlink with wrong pads. The unlink
773 * function would catch this and safely return failed. */
774 if (GST_PAD_IS_SRC (pad))
775 gst_pad_unlink (pad, peer);
777 gst_pad_unlink (peer, pad);
779 gst_object_unref (peer);
782 GST_OBJECT_LOCK (element);
783 /* remove it from the list */
784 switch (gst_pad_get_direction (pad)) {
786 element->srcpads = g_list_remove (element->srcpads, pad);
787 element->numsrcpads--;
790 element->sinkpads = g_list_remove (element->sinkpads, pad);
791 element->numsinkpads--;
794 g_critical ("Removing pad without direction???");
797 element->pads = g_list_remove (element->pads, pad);
799 element->pads_cookie++;
800 GST_OBJECT_UNLOCK (element);
802 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
803 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
805 gst_object_unparent (GST_OBJECT_CAST (pad));
812 /* locking order is element > pad */
813 GST_OBJECT_UNLOCK (pad);
815 GST_OBJECT_LOCK (element);
816 GST_OBJECT_LOCK (pad);
817 g_critical ("Padname %s:%s does not belong to element %s when removing",
818 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
819 GST_OBJECT_UNLOCK (pad);
820 GST_OBJECT_UNLOCK (element);
826 * gst_element_no_more_pads:
827 * @element: a #GstElement
829 * Use this function to signal that the element does not expect any more pads
830 * to show up in the current pipeline. This function should be called whenever
831 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
832 * pad templates use this in combination with autopluggers to figure out that
833 * the element is done initializing its pads.
835 * This function emits the #GstElement::no-more-pads signal.
840 gst_element_no_more_pads (GstElement * element)
842 g_return_if_fail (GST_IS_ELEMENT (element));
844 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
848 pad_compare_name (GstPad * pad1, const gchar * name)
852 GST_OBJECT_LOCK (pad1);
853 result = strcmp (GST_PAD_NAME (pad1), name);
854 GST_OBJECT_UNLOCK (pad1);
860 * gst_element_get_static_pad:
861 * @element: a #GstElement to find a static pad of.
862 * @name: the name of the static #GstPad to retrieve.
864 * Retrieves a pad from @element by name. This version only retrieves
865 * already-existing (i.e. 'static') pads.
867 * Returns: (transfer full): the requested #GstPad if found, otherwise %NULL.
873 gst_element_get_static_pad (GstElement * element, const gchar * name)
876 GstPad *result = NULL;
878 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
879 g_return_val_if_fail (name != NULL, NULL);
881 GST_OBJECT_LOCK (element);
883 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
885 result = GST_PAD_CAST (find->data);
886 gst_object_ref (result);
889 if (result == NULL) {
890 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
891 name, GST_ELEMENT_NAME (element));
893 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
894 GST_ELEMENT_NAME (element), name);
896 GST_OBJECT_UNLOCK (element);
902 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
903 const gchar * name, const GstCaps * caps)
905 GstPad *newpad = NULL;
906 GstElementClass *oclass;
908 oclass = GST_ELEMENT_GET_CLASS (element);
910 #ifndef G_DISABLE_CHECKS
911 /* Some sanity checking here */
915 /* Is this the template name? */
916 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
917 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
919 const gchar *str, *data;
922 /* Otherwise check if it's a valid name for the name template */
923 str = strchr (templ->name_template, '%');
924 g_return_val_if_fail (str != NULL, NULL);
925 g_return_val_if_fail (strncmp (templ->name_template, name,
926 str - templ->name_template) == 0, NULL);
927 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
929 data = name + (str - templ->name_template);
931 /* Can either be %s or %d or %u, do sanity checking for %d */
932 if (*(str + 1) == 'd') {
936 tmp = g_ascii_strtoll (data, &endptr, 10);
937 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
938 && *endptr == '\0', NULL);
939 } else if (*(str + 1) == 'u') {
943 tmp = g_ascii_strtoull (data, &endptr, 10);
944 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
948 pad = gst_element_get_static_pad (element, name);
950 gst_object_unref (pad);
951 /* FIXME 0.11: Change this to g_return_val_if_fail() */
952 g_critical ("Element %s already has a pad named %s, the behaviour of "
953 " gst_element_get_request_pad() for existing pads is undefined!",
954 GST_ELEMENT_NAME (element), name);
959 if (oclass->request_new_pad)
960 newpad = (oclass->request_new_pad) (element, templ, name, caps);
963 gst_object_ref (newpad);
969 * gst_element_get_request_pad:
970 * @element: a #GstElement to find a request pad of.
971 * @name: the name of the request #GstPad to retrieve.
973 * Retrieves a pad from the element by name (e.g. "src_\%d"). This version only
974 * retrieves request pads. The pad should be released with
975 * gst_element_release_request_pad().
977 * This method is slow and will be deprecated in the future. New code should
978 * use gst_element_request_pad() with the requested template.
980 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
981 * Release after usage.
984 gst_element_get_request_pad (GstElement * element, const gchar * name)
986 GstPadTemplate *templ = NULL;
988 const gchar *req_name = NULL;
989 gboolean templ_found = FALSE;
992 gchar *str, *endptr = NULL;
993 GstElementClass *class;
995 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
996 g_return_val_if_fail (name != NULL, NULL);
998 class = GST_ELEMENT_GET_CLASS (element);
1000 /* if the name contains a %, we assume it's the complete template name. Get
1001 * the template and try to get a pad */
1002 if (strstr (name, "%")) {
1003 templ = gst_element_class_get_request_pad_template (class, name);
1008 /* there is no % in the name, try to find a matching template */
1009 list = class->padtemplates;
1010 while (!templ_found && list) {
1011 templ = (GstPadTemplate *) list->data;
1012 if (templ->presence == GST_PAD_REQUEST) {
1013 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1014 templ->name_template);
1015 /* see if we find an exact match */
1016 if (strcmp (name, templ->name_template) == 0) {
1021 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1022 and %d and %u, occurring at the end of the name_template, are the only
1024 else if ((str = strchr (templ->name_template, '%'))
1025 && strncmp (templ->name_template, name,
1026 str - templ->name_template) == 0
1027 && strlen (name) > str - templ->name_template) {
1028 data = name + (str - templ->name_template);
1029 if (*(str + 1) == 'd') {
1033 tmp = strtol (data, &endptr, 10);
1034 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1040 } else if (*(str + 1) == 'u') {
1044 tmp = strtoul (data, &endptr, 10);
1045 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1065 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1071 * gst_element_request_pad:
1072 * @element: a #GstElement to find a request pad of.
1073 * @templ: a #GstPadTemplate of which we want a pad of.
1074 * @name: (transfer none) (allow-none): the name of the request #GstPad
1075 * to retrieve. Can be %NULL.
1076 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1077 * request. Can be %NULL.
1079 * Retrieves a request pad from the element according to the provided template.
1080 * Pad templates can be looked up using
1081 * gst_element_factory_get_static_pad_templates().
1083 * The pad should be released with gst_element_release_request_pad().
1085 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1086 * Release after usage.
1091 gst_element_request_pad (GstElement * element,
1092 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1094 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1095 g_return_val_if_fail (templ != NULL, NULL);
1097 return _gst_element_request_pad (element, templ, name, caps);
1100 static GstIterator *
1101 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1103 GstIterator *result;
1105 GST_OBJECT_LOCK (element);
1106 result = gst_iterator_new_list (GST_TYPE_PAD,
1107 GST_OBJECT_GET_LOCK (element),
1108 &element->pads_cookie, padlist, (GObject *) element, NULL);
1109 GST_OBJECT_UNLOCK (element);
1115 * gst_element_iterate_pads:
1116 * @element: a #GstElement to iterate pads of.
1118 * Retrieves an iterator of @element's pads. The iterator should
1119 * be freed after usage. Also more specialized iterators exists such as
1120 * gst_element_iterate_src_pads() or gst_element_iterate_sink_pads().
1122 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1128 gst_element_iterate_pads (GstElement * element)
1130 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1132 return gst_element_iterate_pad_list (element, &element->pads);
1136 * gst_element_iterate_src_pads:
1137 * @element: a #GstElement.
1139 * Retrieves an iterator of @element's source pads.
1141 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1147 gst_element_iterate_src_pads (GstElement * element)
1149 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1151 return gst_element_iterate_pad_list (element, &element->srcpads);
1155 * gst_element_iterate_sink_pads:
1156 * @element: a #GstElement.
1158 * Retrieves an iterator of @element's sink pads.
1160 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1166 gst_element_iterate_sink_pads (GstElement * element)
1168 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1170 return gst_element_iterate_pad_list (element, &element->sinkpads);
1174 * gst_element_class_add_pad_template:
1175 * @klass: the #GstElementClass to add the pad template to.
1176 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1178 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1179 * functions of classes. If a pad template with the same name as an already
1180 * existing one is added the old one is replaced by the new one.
1184 gst_element_class_add_pad_template (GstElementClass * klass,
1185 GstPadTemplate * templ)
1187 GList *template_list = klass->padtemplates;
1189 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1190 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1192 /* If we already have a pad template with the same name replace the
1194 while (template_list) {
1195 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1197 /* Found pad with the same name, replace and return */
1198 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1199 gst_object_unref (padtempl);
1200 template_list->data = templ;
1203 template_list = g_list_next (template_list);
1206 /* Take ownership of the floating ref */
1207 gst_object_ref_sink (templ);
1209 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1210 klass->numpadtemplates++;
1214 * gst_element_class_add_metadata:
1215 * @klass: class to set metadata for
1216 * @key: the key to set
1217 * @value: the value to set
1219 * Set @key with @value as metadata in @klass.
1222 gst_element_class_add_metadata (GstElementClass * klass,
1223 const gchar * key, const gchar * value)
1225 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1226 g_return_if_fail (key != NULL);
1227 g_return_if_fail (value != NULL);
1229 gst_structure_set ((GstStructure *) klass->metadata,
1230 key, G_TYPE_STRING, value, NULL);
1234 * gst_element_class_add_static_metadata:
1235 * @klass: class to set metadata for
1236 * @key: the key to set
1237 * @value: the value to set
1239 * Set @key with @value as metadata in @klass.
1241 * Same as gst_element_class_add_metadata(), but @value must be a static string
1242 * or an inlined string, as it will not be copied. (GStreamer plugins will
1243 * be made resident once loaded, so this function can be used even from
1244 * dynamically loaded plugins.)
1247 gst_element_class_add_static_metadata (GstElementClass * klass,
1248 const gchar * key, const gchar * value)
1250 GValue val = G_VALUE_INIT;
1252 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1253 g_return_if_fail (key != NULL);
1254 g_return_if_fail (value != NULL);
1256 g_value_init (&val, G_TYPE_STRING);
1257 g_value_set_static_string (&val, value);
1258 gst_structure_take_value ((GstStructure *) klass->metadata, key, &val);
1262 * gst_element_class_set_metadata:
1263 * @klass: class to set metadata for
1264 * @longname: The long English name of the element. E.g. "File Sink"
1265 * @classification: String describing the type of element, as an unordered list
1266 * separated with slashes ('/'). See draft-klass.txt of the design docs
1267 * for more details and common types. E.g: "Sink/File"
1268 * @description: Sentence describing the purpose of the element.
1269 * E.g: "Write stream to a file"
1270 * @author: Name and contact details of the author(s). Use \n to separate
1271 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1273 * Sets the detailed information for a #GstElementClass.
1274 * <note>This function is for use in _class_init functions only.</note>
1277 gst_element_class_set_metadata (GstElementClass * klass,
1278 const gchar * longname, const gchar * classification,
1279 const gchar * description, const gchar * author)
1281 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1283 gst_structure_id_set ((GstStructure *) klass->metadata,
1284 GST_QUARK (ELEMENT_METADATA_LONGNAME), G_TYPE_STRING, longname,
1285 GST_QUARK (ELEMENT_METADATA_KLASS), G_TYPE_STRING, classification,
1286 GST_QUARK (ELEMENT_METADATA_DESCRIPTION), G_TYPE_STRING, description,
1287 GST_QUARK (ELEMENT_METADATA_AUTHOR), G_TYPE_STRING, author, NULL);
1291 * gst_element_class_set_static_metadata:
1292 * @klass: class to set metadata for
1293 * @longname: The long English name of the element. E.g. "File Sink"
1294 * @classification: String describing the type of element, as an unordered list
1295 * separated with slashes ('/'). See draft-klass.txt of the design docs
1296 * for more details and common types. E.g: "Sink/File"
1297 * @description: Sentence describing the purpose of the element.
1298 * E.g: "Write stream to a file"
1299 * @author: Name and contact details of the author(s). Use \n to separate
1300 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1302 * Sets the detailed information for a #GstElementClass.
1303 * <note>This function is for use in _class_init functions only.</note>
1305 * Same as gst_element_class_set_metadata(), but @longname, @classification,
1306 * @description, and @author must be static strings or inlined strings, as
1307 * they will not be copied. (GStreamer plugins will be made resident once
1308 * loaded, so this function can be used even from dynamically loaded plugins.)
1311 gst_element_class_set_static_metadata (GstElementClass * klass,
1312 const gchar * longname, const gchar * classification,
1313 const gchar * description, const gchar * author)
1315 GstStructure *s = (GstStructure *) klass->metadata;
1316 GValue val = G_VALUE_INIT;
1318 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1320 g_value_init (&val, G_TYPE_STRING);
1322 g_value_set_static_string (&val, longname);
1323 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_LONGNAME), &val);
1325 g_value_set_static_string (&val, classification);
1326 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_KLASS), &val);
1328 g_value_set_static_string (&val, description);
1329 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_DESCRIPTION),
1332 g_value_set_static_string (&val, author);
1333 gst_structure_id_take_value (s, GST_QUARK (ELEMENT_METADATA_AUTHOR), &val);
1337 * gst_element_class_get_metadata:
1338 * @klass: class to get metadata for
1339 * @key: the key to get
1341 * Get metadata with @key in @klass.
1343 * Returns: the metadata for @key.
1346 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1348 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1349 g_return_val_if_fail (key != NULL, NULL);
1351 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1355 * gst_element_class_get_pad_template_list:
1356 * @element_class: a #GstElementClass to get pad templates of.
1358 * Retrieves a list of the pad templates associated with @element_class. The
1359 * list must not be modified by the calling code.
1360 * <note>If you use this function in the #GInstanceInitFunc of an object class
1361 * that has subclasses, make sure to pass the g_class parameter of the
1362 * #GInstanceInitFunc here.</note>
1364 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1368 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1370 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1372 return element_class->padtemplates;
1376 * gst_element_class_get_pad_template:
1377 * @element_class: a #GstElementClass to get the pad template of.
1378 * @name: the name of the #GstPadTemplate to get.
1380 * Retrieves a padtemplate from @element_class with the given name.
1381 * <note>If you use this function in the #GInstanceInitFunc of an object class
1382 * that has subclasses, make sure to pass the g_class parameter of the
1383 * #GInstanceInitFunc here.</note>
1385 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1386 * if none was found. No unreferencing is necessary.
1389 gst_element_class_get_pad_template (GstElementClass *
1390 element_class, const gchar * name)
1394 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1395 g_return_val_if_fail (name != NULL, NULL);
1397 padlist = element_class->padtemplates;
1400 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1402 if (strcmp (padtempl->name_template, name) == 0)
1405 padlist = g_list_next (padlist);
1411 static GstPadTemplate *
1412 gst_element_class_get_request_pad_template (GstElementClass *
1413 element_class, const gchar * name)
1415 GstPadTemplate *tmpl;
1417 tmpl = gst_element_class_get_pad_template (element_class, name);
1418 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1424 /* get a random pad on element of the given direction.
1425 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1428 gst_element_get_random_pad (GstElement * element,
1429 gboolean need_linked, GstPadDirection dir)
1431 GstPad *result = NULL;
1434 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1438 GST_OBJECT_LOCK (element);
1439 pads = element->srcpads;
1442 GST_OBJECT_LOCK (element);
1443 pads = element->sinkpads;
1446 goto wrong_direction;
1448 for (; pads; pads = g_list_next (pads)) {
1449 GstPad *pad = GST_PAD_CAST (pads->data);
1451 GST_OBJECT_LOCK (pad);
1452 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1453 GST_DEBUG_PAD_NAME (pad));
1455 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1456 /* if we require a linked pad, and it is not linked, continue the
1458 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1459 GST_DEBUG_PAD_NAME (pad));
1460 GST_OBJECT_UNLOCK (pad);
1463 /* found a pad, stop search */
1464 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1465 GST_DEBUG_PAD_NAME (pad));
1466 GST_OBJECT_UNLOCK (pad);
1472 gst_object_ref (result);
1474 GST_OBJECT_UNLOCK (element);
1478 /* ERROR handling */
1481 g_warning ("unknown pad direction %d", dir);
1487 gst_element_default_send_event (GstElement * element, GstEvent * event)
1489 gboolean result = FALSE;
1492 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1493 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1494 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1497 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1498 "pushing %s event to random %s pad %s:%s",
1499 GST_EVENT_TYPE_NAME (event),
1500 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1501 GST_DEBUG_PAD_NAME (pad));
1503 result = gst_pad_push_event (pad, event);
1504 gst_object_unref (pad);
1506 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1507 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1508 gst_event_unref (event);
1514 * gst_element_send_event:
1515 * @element: a #GstElement to send the event to.
1516 * @event: (transfer full): the #GstEvent to send to the element.
1518 * Sends an event to an element. If the element doesn't implement an
1519 * event handler, the event will be pushed on a random linked sink pad for
1520 * upstream events or a random linked source pad for downstream events.
1522 * This function takes owership of the provided event so you should
1523 * gst_event_ref() it if you want to reuse the event after this call.
1525 * Returns: %TRUE if the event was handled.
1530 gst_element_send_event (GstElement * element, GstEvent * event)
1532 GstElementClass *oclass;
1533 gboolean result = FALSE;
1535 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1536 g_return_val_if_fail (event != NULL, FALSE);
1538 oclass = GST_ELEMENT_GET_CLASS (element);
1540 GST_STATE_LOCK (element);
1541 if (oclass->send_event) {
1542 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1543 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1544 result = oclass->send_event (element, event);
1546 GST_STATE_UNLOCK (element);
1553 * @element: a #GstElement to send the event to.
1554 * @rate: The new playback rate
1555 * @format: The format of the seek values
1556 * @flags: The optional seek flags.
1557 * @cur_type: The type and flags for the new current position
1558 * @cur: The value of the new current position
1559 * @stop_type: The type and flags for the new stop position
1560 * @stop: The value of the new stop position
1562 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1563 * the parameters. The seek event is sent to the element using
1564 * gst_element_send_event().
1566 * Returns: %TRUE if the event was handled.
1571 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1572 GstSeekFlags flags, GstSeekType cur_type, gint64 cur,
1573 GstSeekType stop_type, gint64 stop)
1578 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1581 gst_event_new_seek (rate, format, flags, cur_type, cur, stop_type, stop);
1582 result = gst_element_send_event (element, event);
1588 gst_element_default_query (GstElement * element, GstQuery * query)
1590 gboolean result = FALSE;
1593 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1595 result = gst_pad_query (pad, query);
1597 gst_object_unref (pad);
1599 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1601 GstPad *peer = gst_pad_get_peer (pad);
1604 result = gst_pad_query (peer, query);
1606 gst_object_unref (peer);
1608 gst_object_unref (pad);
1615 * gst_element_query:
1616 * @element: a #GstElement to perform the query on.
1617 * @query: (transfer none): the #GstQuery.
1619 * Performs a query on the given element.
1621 * For elements that don't implement a query handler, this function
1622 * forwards the query to a random srcpad or to the peer of a
1623 * random linked sinkpad of this element.
1625 * Please note that some queries might need a running pipeline to work.
1627 * Returns: TRUE if the query could be performed.
1632 gst_element_query (GstElement * element, GstQuery * query)
1634 GstElementClass *oclass;
1635 gboolean result = FALSE;
1637 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1638 g_return_val_if_fail (query != NULL, FALSE);
1640 oclass = GST_ELEMENT_GET_CLASS (element);
1642 if (oclass->query) {
1643 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1644 GST_ELEMENT_NAME (element));
1645 result = oclass->query (element, query);
1651 * gst_element_post_message:
1652 * @element: a #GstElement posting the message
1653 * @message: (transfer full): a #GstMessage to post
1655 * Post a message on the element's #GstBus. This function takes ownership of the
1656 * message; if you want to access the message after this call, you should add an
1657 * additional reference before calling.
1659 * Returns: %TRUE if the message was successfully posted. The function returns
1660 * %FALSE if the element did not have a bus.
1665 gst_element_post_message (GstElement * element, GstMessage * message)
1668 gboolean result = FALSE;
1670 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1671 g_return_val_if_fail (message != NULL, FALSE);
1673 GST_OBJECT_LOCK (element);
1676 if (G_UNLIKELY (bus == NULL))
1679 gst_object_ref (bus);
1680 GST_OBJECT_UNLOCK (element);
1682 /* we release the element lock when posting the message so that any
1683 * (synchronous) message handlers can operate on the element */
1684 result = gst_bus_post (bus, message);
1685 gst_object_unref (bus);
1692 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1693 "not posting message %p: no bus", message);
1694 GST_OBJECT_UNLOCK (element);
1695 gst_message_unref (message);
1701 * _gst_element_error_printf:
1702 * @format: the printf-like format to use, or %NULL
1704 * This function is only used internally by the gst_element_error() macro.
1706 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1712 _gst_element_error_printf (const gchar * format, ...)
1722 va_start (args, format);
1723 buffer = g_strdup_vprintf (format, args);
1729 * gst_element_message_full:
1730 * @element: a #GstElement to send message from
1731 * @type: the #GstMessageType
1732 * @domain: the GStreamer GError domain this message belongs to
1733 * @code: the GError code belonging to the domain
1734 * @text: (allow-none) (transfer full): an allocated text string to be used
1735 * as a replacement for the default message connected to code,
1737 * @debug: (allow-none) (transfer full): an allocated debug message to be
1738 * used as a replacement for the default debugging information,
1740 * @file: the source code file where the error was generated
1741 * @function: the source code function where the error was generated
1742 * @line: the source code line where the error was generated
1744 * Post an error, warning or info message on the bus from inside an element.
1746 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1747 * #GST_MESSAGE_INFO.
1751 void gst_element_message_full
1752 (GstElement * element, GstMessageType type,
1753 GQuark domain, gint code, gchar * text,
1754 gchar * debug, const gchar * file, const gchar * function, gint line)
1756 GError *gerror = NULL;
1760 gboolean has_debug = TRUE;
1761 GstMessage *message = NULL;
1764 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1765 g_return_if_fail (GST_IS_ELEMENT (element));
1766 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1767 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1769 /* check if we send the given text or the default error text */
1770 if ((text == NULL) || (text[0] == 0)) {
1771 /* text could have come from g_strdup_printf (""); */
1773 sent_text = gst_error_get_message (domain, code);
1777 /* construct a sent_debug with extra information from source */
1778 if ((debug == NULL) || (debug[0] == 0)) {
1779 /* debug could have come from g_strdup_printf (""); */
1783 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1785 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1786 file, line, function, name, debug);
1788 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1789 file, line, function, name);
1793 /* create gerror and post message */
1794 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1796 gerror = g_error_new_literal (domain, code, sent_text);
1799 case GST_MESSAGE_ERROR:
1801 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1803 case GST_MESSAGE_WARNING:
1804 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1807 case GST_MESSAGE_INFO:
1808 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1812 g_assert_not_reached ();
1815 gst_element_post_message (element, message);
1817 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1818 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1821 g_error_free (gerror);
1822 g_free (sent_debug);
1827 * gst_element_is_locked_state:
1828 * @element: a #GstElement.
1830 * Checks if the state of an element is locked.
1831 * If the state of an element is locked, state changes of the parent don't
1832 * affect the element.
1833 * This way you can leave currently unused elements inside bins. Just lock their
1834 * state before changing the state from #GST_STATE_NULL.
1838 * Returns: TRUE, if the element's state is locked.
1841 gst_element_is_locked_state (GstElement * element)
1845 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1847 GST_OBJECT_LOCK (element);
1848 result = GST_ELEMENT_IS_LOCKED_STATE (element);
1849 GST_OBJECT_UNLOCK (element);
1855 * gst_element_set_locked_state:
1856 * @element: a #GstElement
1857 * @locked_state: TRUE to lock the element's state
1859 * Locks the state of an element, so state changes of the parent don't affect
1860 * this element anymore.
1864 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1865 * or the elements state-locking needed no change.
1868 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1872 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1874 GST_OBJECT_LOCK (element);
1875 old = GST_ELEMENT_IS_LOCKED_STATE (element);
1877 if (G_UNLIKELY (old == locked_state))
1881 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1882 GST_ELEMENT_NAME (element));
1883 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1885 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1886 GST_ELEMENT_NAME (element));
1887 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1889 GST_OBJECT_UNLOCK (element);
1895 GST_CAT_DEBUG (GST_CAT_STATES,
1896 "elements %s was already in locked state %d",
1897 GST_ELEMENT_NAME (element), old);
1898 GST_OBJECT_UNLOCK (element);
1905 * gst_element_sync_state_with_parent:
1906 * @element: a #GstElement.
1908 * Tries to change the state of the element to the same as its parent.
1909 * If this function returns FALSE, the state of element is undefined.
1911 * Returns: TRUE, if the element's state could be synced to the parent's state.
1916 gst_element_sync_state_with_parent (GstElement * element)
1920 GstStateChangeReturn ret;
1922 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1924 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1925 GstState parent_current, parent_pending;
1927 GST_OBJECT_LOCK (parent);
1928 parent_current = GST_STATE (parent);
1929 parent_pending = GST_STATE_PENDING (parent);
1930 GST_OBJECT_UNLOCK (parent);
1932 /* set to pending if there is one, else we set it to the current state of
1934 if (parent_pending != GST_STATE_VOID_PENDING)
1935 target = parent_pending;
1937 target = parent_current;
1939 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1940 "syncing state (%s) to parent %s %s (%s, %s)",
1941 gst_element_state_get_name (GST_STATE (element)),
1942 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1943 gst_element_state_get_name (parent_current),
1944 gst_element_state_get_name (parent_pending));
1946 ret = gst_element_set_state (element, target);
1947 if (ret == GST_STATE_CHANGE_FAILURE)
1950 gst_object_unref (parent);
1954 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
1961 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1962 "syncing state failed (%s)",
1963 gst_element_state_change_return_get_name (ret));
1964 gst_object_unref (parent);
1970 static GstStateChangeReturn
1971 gst_element_get_state_func (GstElement * element,
1972 GstState * state, GstState * pending, GstClockTime timeout)
1974 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
1975 GstState old_pending;
1977 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
1978 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
1980 GST_OBJECT_LOCK (element);
1981 ret = GST_STATE_RETURN (element);
1982 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
1983 gst_element_state_change_return_get_name (ret));
1985 /* we got an error, report immediately */
1986 if (ret == GST_STATE_CHANGE_FAILURE)
1989 /* we got no_preroll, report immediately */
1990 if (ret == GST_STATE_CHANGE_NO_PREROLL)
1993 /* no need to wait async if we are not async */
1994 if (ret != GST_STATE_CHANGE_ASYNC)
1997 old_pending = GST_STATE_PENDING (element);
1998 if (old_pending != GST_STATE_VOID_PENDING) {
2002 /* get cookie to detect state changes during waiting */
2003 cookie = element->state_cookie;
2005 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2006 "waiting for element to commit state");
2008 /* we have a pending state change, wait for it to complete */
2009 if (timeout != GST_CLOCK_TIME_NONE) {
2011 /* make timeout absolute */
2012 end_time = g_get_monotonic_time () + (timeout / 1000);
2013 signaled = GST_STATE_WAIT_UNTIL (element, end_time);
2015 GST_STATE_WAIT (element);
2020 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2021 /* timeout triggered */
2022 ret = GST_STATE_CHANGE_ASYNC;
2024 if (cookie != element->state_cookie)
2027 /* could be success or failure */
2028 if (old_pending == GST_STATE (element)) {
2029 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2030 ret = GST_STATE_CHANGE_SUCCESS;
2032 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2033 ret = GST_STATE_CHANGE_FAILURE;
2036 /* if nothing is pending anymore we can return SUCCESS */
2037 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2038 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2039 ret = GST_STATE_CHANGE_SUCCESS;
2045 *state = GST_STATE (element);
2047 *pending = GST_STATE_PENDING (element);
2049 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2050 "state current: %s, pending: %s, result: %s",
2051 gst_element_state_get_name (GST_STATE (element)),
2052 gst_element_state_get_name (GST_STATE_PENDING (element)),
2053 gst_element_state_change_return_get_name (ret));
2054 GST_OBJECT_UNLOCK (element);
2061 *state = GST_STATE_VOID_PENDING;
2063 *pending = GST_STATE_VOID_PENDING;
2065 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2067 GST_OBJECT_UNLOCK (element);
2069 return GST_STATE_CHANGE_FAILURE;
2074 * gst_element_get_state:
2075 * @element: a #GstElement to get the state of.
2076 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2078 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2079 * state. Can be %NULL.
2080 * @timeout: a #GstClockTime to specify the timeout for an async
2081 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2083 * Gets the state of the element.
2085 * For elements that performed an ASYNC state change, as reported by
2086 * gst_element_set_state(), this function will block up to the
2087 * specified timeout value for the state change to complete.
2088 * If the element completes the state change or goes into
2089 * an error, this function returns immediately with a return value of
2090 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2092 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2093 * returns the current and pending state immediately.
2095 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2096 * successfully changed its state but is not able to provide data yet.
2097 * This mostly happens for live sources that only produce data in
2098 * %GST_STATE_PLAYING. While the state change return is equivalent to
2099 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2100 * some sink elements might not be able to complete their state change because
2101 * an element is not producing data to complete the preroll. When setting the
2102 * element to playing, the preroll will complete and playback will start.
2104 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2105 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2106 * element is still performing a state change or
2107 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2111 GstStateChangeReturn
2112 gst_element_get_state (GstElement * element,
2113 GstState * state, GstState * pending, GstClockTime timeout)
2115 GstElementClass *oclass;
2116 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2118 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2120 oclass = GST_ELEMENT_GET_CLASS (element);
2122 if (oclass->get_state)
2123 result = (oclass->get_state) (element, state, pending, timeout);
2129 * gst_element_abort_state:
2130 * @element: a #GstElement to abort the state of.
2132 * Abort the state change of the element. This function is used
2133 * by elements that do asynchronous state changes and find out
2134 * something is wrong.
2136 * This function should be called with the STATE_LOCK held.
2141 gst_element_abort_state (GstElement * element)
2145 #ifndef GST_DISABLE_GST_DEBUG
2149 g_return_if_fail (GST_IS_ELEMENT (element));
2151 GST_OBJECT_LOCK (element);
2152 pending = GST_STATE_PENDING (element);
2154 if (pending == GST_STATE_VOID_PENDING ||
2155 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2156 goto nothing_aborted;
2158 #ifndef GST_DISABLE_GST_DEBUG
2159 old_state = GST_STATE (element);
2161 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2162 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2163 gst_element_state_get_name (pending));
2167 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2169 GST_STATE_BROADCAST (element);
2170 GST_OBJECT_UNLOCK (element);
2176 GST_OBJECT_UNLOCK (element);
2181 /* Not static because GstBin has manual state handling too */
2183 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2184 GstState newstate, GstState pending)
2186 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2187 GstMessage *message;
2189 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2190 "notifying about state-changed %s to %s (%s pending)",
2191 gst_element_state_get_name (oldstate),
2192 gst_element_state_get_name (newstate),
2193 gst_element_state_get_name (pending));
2195 if (klass->state_changed)
2196 klass->state_changed (element, oldstate, newstate, pending);
2198 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2199 oldstate, newstate, pending);
2200 gst_element_post_message (element, message);
2204 * gst_element_continue_state:
2205 * @element: a #GstElement to continue the state change of.
2206 * @ret: The previous state return value
2208 * Commit the state change of the element and proceed to the next
2209 * pending state if any. This function is used
2210 * by elements that do asynchronous state changes.
2211 * The core will normally call this method automatically when an
2212 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2214 * If after calling this method the element still has not reached
2215 * the pending state, the next state change is performed.
2217 * This method is used internally and should normally not be called by plugins
2220 * Returns: The result of the commit state change.
2224 GstStateChangeReturn
2225 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2227 GstStateChangeReturn old_ret;
2228 GstState old_state, old_next;
2229 GstState current, next, pending;
2230 GstStateChange transition;
2232 GST_OBJECT_LOCK (element);
2233 old_ret = GST_STATE_RETURN (element);
2234 GST_STATE_RETURN (element) = ret;
2235 pending = GST_STATE_PENDING (element);
2237 /* check if there is something to commit */
2238 if (pending == GST_STATE_VOID_PENDING)
2239 goto nothing_pending;
2241 old_state = GST_STATE (element);
2242 /* this is the state we should go to next */
2243 old_next = GST_STATE_NEXT (element);
2244 /* update current state */
2245 current = GST_STATE (element) = old_next;
2247 /* see if we reached the final state */
2248 if (pending == current)
2251 next = GST_STATE_GET_NEXT (current, pending);
2252 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2254 GST_STATE_NEXT (element) = next;
2256 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2257 GST_OBJECT_UNLOCK (element);
2259 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2260 "committing state from %s to %s, pending %s, next %s",
2261 gst_element_state_get_name (old_state),
2262 gst_element_state_get_name (old_next),
2263 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2265 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2267 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2268 "continue state change %s to %s, final %s",
2269 gst_element_state_get_name (current),
2270 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2272 ret = gst_element_change_state (element, transition);
2278 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2279 GST_OBJECT_UNLOCK (element);
2284 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2285 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2287 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2288 "completed state change to %s", gst_element_state_get_name (pending));
2289 GST_OBJECT_UNLOCK (element);
2291 /* don't post silly messages with the same state. This can happen
2292 * when an element state is changed to what it already was. For bins
2293 * this can be the result of a lost state, which we check with the
2294 * previous return value.
2295 * We do signal the cond though as a _get_state() might be blocking
2297 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2298 _priv_gst_element_state_changed (element, old_state, old_next,
2299 GST_STATE_VOID_PENDING);
2301 GST_STATE_BROADCAST (element);
2308 * gst_element_lost_state:
2309 * @element: a #GstElement the state is lost of
2311 * Brings the element to the lost state. The current state of the
2312 * element is copied to the pending state so that any call to
2313 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2315 * An ASYNC_START message is posted. If the element was PLAYING, it will
2316 * go to PAUSED. The element will be restored to its PLAYING state by
2317 * the parent pipeline when it prerolls again.
2319 * This is mostly used for elements that lost their preroll buffer
2320 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2321 * they will go to their pending state again when a new preroll buffer is
2322 * queued. This function can only be called when the element is currently
2323 * not in error or an async state change.
2325 * This function is used internally and should normally not be called from
2326 * plugins or applications.
2329 gst_element_lost_state (GstElement * element)
2331 GstState old_state, new_state;
2332 GstMessage *message;
2334 g_return_if_fail (GST_IS_ELEMENT (element));
2336 GST_OBJECT_LOCK (element);
2337 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2340 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2341 goto only_async_start;
2343 old_state = GST_STATE (element);
2345 /* when we were PLAYING, the new state is PAUSED. We will also not
2346 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2347 * when we preroll. */
2348 if (old_state > GST_STATE_PAUSED)
2349 new_state = GST_STATE_PAUSED;
2351 new_state = old_state;
2353 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2354 "lost state of %s to %s", gst_element_state_get_name (old_state),
2355 gst_element_state_get_name (new_state));
2357 GST_STATE (element) = new_state;
2358 GST_STATE_NEXT (element) = new_state;
2359 GST_STATE_PENDING (element) = new_state;
2360 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2361 GST_OBJECT_UNLOCK (element);
2363 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2365 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2366 gst_element_post_message (element, message);
2372 GST_OBJECT_UNLOCK (element);
2377 GST_OBJECT_UNLOCK (element);
2379 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2380 gst_element_post_message (element, message);
2386 * gst_element_set_state:
2387 * @element: a #GstElement to change state of.
2388 * @state: the element's new #GstState.
2390 * Sets the state of the element. This function will try to set the
2391 * requested state by going through all the intermediary states and calling
2392 * the class's state change function for each.
2394 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2395 * element will perform the remainder of the state change asynchronously in
2397 * An application can use gst_element_get_state() to wait for the completion
2398 * of the state change or it can wait for a state change message on the bus.
2400 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2401 * #GST_STATE_CHANGE_ASYNC.
2403 * Returns: Result of the state change using #GstStateChangeReturn.
2407 GstStateChangeReturn
2408 gst_element_set_state (GstElement * element, GstState state)
2410 GstElementClass *oclass;
2411 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2413 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2415 oclass = GST_ELEMENT_GET_CLASS (element);
2417 if (oclass->set_state)
2418 result = (oclass->set_state) (element, state);
2424 * default set state function, calculates the next state based
2425 * on current state and calls the change_state function
2427 static GstStateChangeReturn
2428 gst_element_set_state_func (GstElement * element, GstState state)
2430 GstState current, next, old_pending;
2431 GstStateChangeReturn ret;
2432 GstStateChange transition;
2433 GstStateChangeReturn old_ret;
2435 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2437 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2438 gst_element_state_get_name (state));
2440 /* state lock is taken to protect the set_state() and get_state()
2441 * procedures, it does not lock any variables. */
2442 GST_STATE_LOCK (element);
2444 /* now calculate how to get to the new state */
2445 GST_OBJECT_LOCK (element);
2446 old_ret = GST_STATE_RETURN (element);
2447 /* previous state change returned an error, remove all pending
2448 * and next states */
2449 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2450 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2451 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2452 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2455 current = GST_STATE (element);
2456 next = GST_STATE_NEXT (element);
2457 old_pending = GST_STATE_PENDING (element);
2459 /* this is the (new) state we should go to. TARGET is the last state we set on
2461 if (state != GST_STATE_TARGET (element)) {
2462 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2463 "setting target state to %s", gst_element_state_get_name (state));
2464 GST_STATE_TARGET (element) = state;
2465 /* increment state cookie so that we can track each state change. We only do
2466 * this if this is actually a new state change. */
2467 element->state_cookie++;
2469 GST_STATE_PENDING (element) = state;
2471 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2472 "current %s, old_pending %s, next %s, old return %s",
2473 gst_element_state_get_name (current),
2474 gst_element_state_get_name (old_pending),
2475 gst_element_state_get_name (next),
2476 gst_element_state_change_return_get_name (old_ret));
2478 /* if the element was busy doing a state change, we just update the
2479 * target state, it'll get to it async then. */
2480 if (old_pending != GST_STATE_VOID_PENDING) {
2481 /* upwards state change will happen ASYNC */
2482 if (old_pending <= state)
2484 /* element is going to this state already */
2485 else if (next == state)
2487 /* element was performing an ASYNC upward state change and
2488 * we request to go downward again. Start from the next pending
2490 else if (next > state
2491 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2495 next = GST_STATE_GET_NEXT (current, state);
2496 /* now we store the next state */
2497 GST_STATE_NEXT (element) = next;
2498 /* mark busy, we need to check that there is actually a state change
2499 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2500 * the default element change_state function has no way to know what the
2501 * old value was... could consider this a FIXME...*/
2502 if (current != next)
2503 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2505 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2507 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2508 "%s: setting state from %s to %s",
2509 (next != state ? "intermediate" : "final"),
2510 gst_element_state_get_name (current), gst_element_state_get_name (next));
2512 /* now signal any waiters, they will error since the cookie was incremented */
2513 GST_STATE_BROADCAST (element);
2515 GST_OBJECT_UNLOCK (element);
2517 ret = gst_element_change_state (element, transition);
2519 GST_STATE_UNLOCK (element);
2521 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2522 gst_element_state_change_return_get_name (ret));
2528 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2529 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2530 "element was busy with async state change");
2531 GST_OBJECT_UNLOCK (element);
2533 GST_STATE_UNLOCK (element);
2535 return GST_STATE_CHANGE_ASYNC;
2540 * gst_element_change_state:
2541 * @element: a #GstElement
2542 * @transition: the requested transition
2544 * Perform @transition on @element.
2546 * This function must be called with STATE_LOCK held and is mainly used
2549 * Returns: the #GstStateChangeReturn of the state transition.
2551 GstStateChangeReturn
2552 gst_element_change_state (GstElement * element, GstStateChange transition)
2554 GstElementClass *oclass;
2555 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2557 oclass = GST_ELEMENT_GET_CLASS (element);
2559 /* call the state change function so it can set the state */
2560 if (oclass->change_state)
2561 ret = (oclass->change_state) (element, transition);
2563 ret = GST_STATE_CHANGE_FAILURE;
2566 case GST_STATE_CHANGE_FAILURE:
2567 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2568 "have FAILURE change_state return");
2569 /* state change failure */
2570 gst_element_abort_state (element);
2572 case GST_STATE_CHANGE_ASYNC:
2576 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2577 "element will change state ASYNC");
2579 target = GST_STATE_TARGET (element);
2581 if (target > GST_STATE_READY)
2584 /* else we just continue the state change downwards */
2585 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2586 "forcing commit state %s <= %s",
2587 gst_element_state_get_name (target),
2588 gst_element_state_get_name (GST_STATE_READY));
2590 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2593 case GST_STATE_CHANGE_SUCCESS:
2594 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2595 "element changed state SUCCESS");
2596 /* we can commit the state now which will proceeed to
2598 ret = gst_element_continue_state (element, ret);
2600 case GST_STATE_CHANGE_NO_PREROLL:
2601 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2602 "element changed state NO_PREROLL");
2603 /* we can commit the state now which will proceeed to
2605 ret = gst_element_continue_state (element, ret);
2608 goto invalid_return;
2611 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2616 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2624 GST_OBJECT_LOCK (element);
2625 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2626 g_critical ("%s: unknown return value %d from a state change function",
2627 GST_ELEMENT_NAME (element), ret);
2629 /* we are in error now */
2630 ret = GST_STATE_CHANGE_FAILURE;
2631 GST_STATE_RETURN (element) = ret;
2632 GST_OBJECT_UNLOCK (element);
2638 /* gst_iterator_fold functions for pads_activate
2639 * Stop the iterator if activating one pad failed. */
2641 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2643 GstPad *pad = g_value_get_object (vpad);
2644 gboolean cont = TRUE;
2646 if (!(cont = gst_pad_set_active (pad, *active)))
2647 g_value_set_boolean (ret, FALSE);
2652 /* returns false on error or early cutout of the fold, true if all
2653 * pads in @iter were (de)activated successfully. */
2655 iterator_activate_fold_with_resync (GstIterator * iter,
2656 GstIteratorFoldFunction func, gpointer user_data)
2658 GstIteratorResult ires;
2661 /* no need to unset this later, it's just a boolean */
2662 g_value_init (&ret, G_TYPE_BOOLEAN);
2663 g_value_set_boolean (&ret, TRUE);
2666 ires = gst_iterator_fold (iter, func, &ret, user_data);
2668 case GST_ITERATOR_RESYNC:
2669 /* need to reset the result again */
2670 g_value_set_boolean (&ret, TRUE);
2671 gst_iterator_resync (iter);
2673 case GST_ITERATOR_DONE:
2674 /* all pads iterated, return collected value */
2677 /* iterator returned _ERROR or premature end with _OK,
2678 * mark an error and exit */
2679 g_value_set_boolean (&ret, FALSE);
2684 /* return collected value */
2685 return g_value_get_boolean (&ret);
2688 /* is called with STATE_LOCK
2690 * Pads are activated from source pads to sinkpads.
2693 gst_element_pads_activate (GstElement * element, gboolean active)
2698 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2699 "pads_activate with active %d", active);
2701 iter = gst_element_iterate_src_pads (element);
2703 iterator_activate_fold_with_resync (iter,
2704 (GstIteratorFoldFunction) activate_pads, &active);
2705 gst_iterator_free (iter);
2706 if (G_UNLIKELY (!res))
2709 iter = gst_element_iterate_sink_pads (element);
2711 iterator_activate_fold_with_resync (iter,
2712 (GstIteratorFoldFunction) activate_pads, &active);
2713 gst_iterator_free (iter);
2714 if (G_UNLIKELY (!res))
2717 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2718 "pads_activate successful");
2725 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2726 "source pads_activate failed");
2731 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2732 "sink pads_activate failed");
2737 /* is called with STATE_LOCK */
2738 static GstStateChangeReturn
2739 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2741 GstState state, next;
2742 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2744 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2746 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2747 next = GST_STATE_TRANSITION_NEXT (transition);
2749 /* if the element already is in the given state, we just return success */
2750 if (next == GST_STATE_VOID_PENDING || state == next)
2753 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2754 "default handler tries setting state from %s to %s (%04x)",
2755 gst_element_state_get_name (state),
2756 gst_element_state_get_name (next), transition);
2758 switch (transition) {
2759 case GST_STATE_CHANGE_NULL_TO_READY:
2761 case GST_STATE_CHANGE_READY_TO_PAUSED:
2762 if (!gst_element_pads_activate (element, TRUE)) {
2763 result = GST_STATE_CHANGE_FAILURE;
2766 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2768 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2770 case GST_STATE_CHANGE_PAUSED_TO_READY:
2771 case GST_STATE_CHANGE_READY_TO_NULL:
2772 /* deactivate pads in both cases, since they are activated on
2773 ready->paused but the element might not have made it to paused */
2774 if (!gst_element_pads_activate (element, FALSE)) {
2775 result = GST_STATE_CHANGE_FAILURE;
2779 /* this will catch real but unhandled state changes;
2780 * can only be caused by:
2781 * - a new state was added
2782 * - somehow the element was asked to jump across an intermediate state
2784 g_warning ("Unhandled state change from %s to %s",
2785 gst_element_state_get_name (state),
2786 gst_element_state_get_name (next));
2793 GST_OBJECT_LOCK (element);
2794 result = GST_STATE_RETURN (element);
2795 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2796 "element is already in the %s state",
2797 gst_element_state_get_name (state));
2798 GST_OBJECT_UNLOCK (element);
2805 * gst_element_get_factory:
2806 * @element: a #GstElement to request the element factory of.
2808 * Retrieves the factory that was used to create this element.
2810 * Returns: (transfer none): the #GstElementFactory used for creating this
2811 * element. no refcounting is needed.
2814 gst_element_get_factory (GstElement * element)
2816 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2818 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2822 gst_element_dispose (GObject * object)
2824 GstElement *element = GST_ELEMENT_CAST (object);
2827 GstElementClass *oclass;
2829 oclass = GST_ELEMENT_GET_CLASS (element);
2831 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2833 if (GST_STATE (element) != GST_STATE_NULL)
2836 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2837 "removing %d pads", g_list_length (element->pads));
2838 /* first we break all our links with the outside */
2839 while (element->pads && element->pads->data) {
2840 GstPad *pad = GST_PAD_CAST (element->pads->data);
2842 /* don't call _remove_pad with NULL */
2843 if (oclass->release_pad && GST_PAD_PAD_TEMPLATE (pad) &&
2844 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
2846 (oclass->release_pad) (element, GST_PAD_CAST (element->pads->data));
2848 gst_element_remove_pad (element, GST_PAD_CAST (element->pads->data));
2850 if (G_UNLIKELY (element->pads != NULL)) {
2851 g_critical ("could not remove pads from element %s",
2852 GST_STR_NULL (GST_OBJECT_NAME (object)));
2855 GST_OBJECT_LOCK (element);
2856 clock_p = &element->clock;
2857 bus_p = &element->bus;
2858 gst_object_replace ((GstObject **) clock_p, NULL);
2859 gst_object_replace ((GstObject **) bus_p, NULL);
2860 GST_OBJECT_UNLOCK (element);
2862 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2864 G_OBJECT_CLASS (parent_class)->dispose (object);
2873 is_locked = GST_ELEMENT_IS_LOCKED_STATE (element);
2875 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2877 "You need to explicitly set elements to the NULL state before\n"
2878 "dropping the final reference, to allow them to clean up.\n"
2879 "This problem may also be caused by a refcounting bug in the\n"
2880 "application or some element.\n",
2881 GST_OBJECT_NAME (element),
2882 gst_element_state_get_name (GST_STATE (element)),
2883 is_locked ? " (locked)" : "");
2889 gst_element_finalize (GObject * object)
2891 GstElement *element = GST_ELEMENT_CAST (object);
2893 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2895 g_cond_clear (&element->state_cond);
2896 g_rec_mutex_clear (&element->state_lock);
2898 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2900 G_OBJECT_CLASS (parent_class)->finalize (object);
2904 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2908 g_return_if_fail (GST_IS_ELEMENT (element));
2910 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2912 GST_OBJECT_LOCK (element);
2913 bus_p = &GST_ELEMENT_BUS (element);
2914 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
2915 GST_OBJECT_UNLOCK (element);
2919 * gst_element_set_bus:
2920 * @element: a #GstElement to set the bus of.
2921 * @bus: (transfer none): the #GstBus to set.
2923 * Sets the bus of the element. Increases the refcount on the bus.
2924 * For internal use only, unless you're testing elements.
2929 gst_element_set_bus (GstElement * element, GstBus * bus)
2931 GstElementClass *oclass;
2933 g_return_if_fail (GST_IS_ELEMENT (element));
2935 oclass = GST_ELEMENT_GET_CLASS (element);
2937 if (oclass->set_bus)
2938 oclass->set_bus (element, bus);
2942 * gst_element_get_bus:
2943 * @element: a #GstElement to get the bus of.
2945 * Returns the bus of the element. Note that only a #GstPipeline will provide a
2946 * bus for the application.
2948 * Returns: (transfer full): the element's #GstBus. unref after usage.
2953 gst_element_get_bus (GstElement * element)
2955 GstBus *result = NULL;
2957 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
2959 GST_OBJECT_LOCK (element);
2960 if ((result = GST_ELEMENT_BUS (element)))
2961 gst_object_ref (result);
2962 GST_OBJECT_UNLOCK (element);
2964 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,