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.
507 gst_element_set_start_time (GstElement * element, GstClockTime time)
511 g_return_if_fail (GST_IS_ELEMENT (element));
513 GST_OBJECT_LOCK (element);
514 old = GST_ELEMENT_START_TIME (element);
515 GST_ELEMENT_START_TIME (element) = time;
516 GST_OBJECT_UNLOCK (element);
518 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
519 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
520 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
524 * gst_element_get_start_time:
525 * @element: a #GstElement.
527 * Returns the start time of the element. The start time is the
528 * running time of the clock when this element was last put to PAUSED.
530 * Usually the start_time is managed by a toplevel element such as
535 * Returns: the start time of the element.
538 gst_element_get_start_time (GstElement * element)
542 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
544 GST_OBJECT_LOCK (element);
545 result = GST_ELEMENT_START_TIME (element);
546 GST_OBJECT_UNLOCK (element);
553 * gst_element_set_index:
554 * @element: a #GstElement.
555 * @index: (transfer none): a #GstIndex.
557 * Set @index on the element. The refcount of the index
558 * will be increased, any previously set index is unreffed.
563 gst_element_set_index (GstElement * element, GstIndex * index)
565 GstElementClass *oclass;
567 g_return_if_fail (GST_IS_ELEMENT (element));
568 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
570 oclass = GST_ELEMENT_GET_CLASS (element);
572 if (oclass->set_index)
573 oclass->set_index (element, index);
577 * gst_element_get_index:
578 * @element: a #GstElement.
580 * Gets the index from the element.
582 * Returns: (transfer full): a #GstIndex or %NULL when no index was set on the
583 * element. unref after usage.
588 gst_element_get_index (GstElement * element)
590 GstElementClass *oclass;
591 GstIndex *result = NULL;
593 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
595 oclass = GST_ELEMENT_GET_CLASS (element);
597 if (oclass->get_index)
598 result = oclass->get_index (element);
605 * gst_element_add_pad:
606 * @element: a #GstElement to add the pad to.
607 * @pad: (transfer full): the #GstPad to add to the element.
609 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
610 * see gst_object_set_parent() for refcounting information.
612 * Pads are not automatically activated so elements should perform the needed
613 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
614 * state. See gst_pad_set_active() for more information about activating pads.
616 * The pad and the element should be unlocked when calling this function.
618 * This function will emit the #GstElement::pad-added signal on the element.
620 * Returns: %TRUE if the pad could be added. This function can fail when
621 * a pad with the same name already existed or the pad already had another
627 gst_element_add_pad (GstElement * element, GstPad * pad)
632 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
633 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
635 /* locking pad to look at the name */
636 GST_OBJECT_LOCK (pad);
637 pad_name = g_strdup (GST_PAD_NAME (pad));
638 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
639 GST_STR_NULL (pad_name));
640 flushing = GST_PAD_IS_FLUSHING (pad);
641 GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_NEED_PARENT);
642 GST_OBJECT_UNLOCK (pad);
644 /* then check to see if there's already a pad by that name here */
645 GST_OBJECT_LOCK (element);
646 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
649 /* try to set the pad's parent */
650 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
651 GST_OBJECT_CAST (element))))
654 /* check for flushing pads */
655 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
656 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
657 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
658 "use gst_pad_set_active(pad,TRUE) before adding it.",
659 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
661 GST_OBJECT_LOCK (pad);
662 GST_PAD_UNSET_FLUSHING (pad);
663 GST_OBJECT_UNLOCK (pad);
668 /* add it to the list */
669 switch (gst_pad_get_direction (pad)) {
671 element->srcpads = g_list_append (element->srcpads, pad);
672 element->numsrcpads++;
675 element->sinkpads = g_list_append (element->sinkpads, pad);
676 element->numsinkpads++;
681 element->pads = g_list_append (element->pads, pad);
683 element->pads_cookie++;
684 GST_OBJECT_UNLOCK (element);
686 /* emit the PAD_ADDED signal */
687 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
694 g_critical ("Padname %s is not unique in element %s, not adding",
695 pad_name, GST_ELEMENT_NAME (element));
696 GST_OBJECT_UNLOCK (element);
703 ("Pad %s already has parent when trying to add to element %s",
704 pad_name, GST_ELEMENT_NAME (element));
705 GST_OBJECT_UNLOCK (element);
711 GST_OBJECT_LOCK (pad);
713 ("Trying to add pad %s to element %s, but it has no direction",
714 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
715 GST_OBJECT_UNLOCK (pad);
716 GST_OBJECT_UNLOCK (element);
722 * gst_element_remove_pad:
723 * @element: a #GstElement to remove pad from.
724 * @pad: (transfer full): the #GstPad to remove from the element.
726 * Removes @pad from @element. @pad will be destroyed if it has not been
727 * referenced elsewhere using gst_object_unparent().
729 * This function is used by plugin developers and should not be used
730 * by applications. Pads that were dynamically requested from elements
731 * with gst_element_get_request_pad() should be released with the
732 * gst_element_release_request_pad() function instead.
734 * Pads are not automatically deactivated so elements should perform the needed
735 * steps to deactivate the pad in case this pad is removed in the PAUSED or
736 * PLAYING state. See gst_pad_set_active() for more information about
739 * The pad and the element should be unlocked when calling this function.
741 * This function will emit the #GstElement::pad-removed signal on the element.
743 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
744 * pad does not belong to the provided element.
749 gst_element_remove_pad (GstElement * element, GstPad * pad)
753 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
754 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
756 /* locking pad to look at the name and parent */
757 GST_OBJECT_LOCK (pad);
758 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
759 GST_STR_NULL (GST_PAD_NAME (pad)));
761 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
763 GST_OBJECT_UNLOCK (pad);
766 if ((peer = gst_pad_get_peer (pad))) {
767 /* window for MT unsafeness, someone else could unlink here
768 * and then we call unlink with wrong pads. The unlink
769 * function would catch this and safely return failed. */
770 if (GST_PAD_IS_SRC (pad))
771 gst_pad_unlink (pad, peer);
773 gst_pad_unlink (peer, pad);
775 gst_object_unref (peer);
778 GST_OBJECT_LOCK (element);
779 /* remove it from the list */
780 switch (gst_pad_get_direction (pad)) {
782 element->srcpads = g_list_remove (element->srcpads, pad);
783 element->numsrcpads--;
786 element->sinkpads = g_list_remove (element->sinkpads, pad);
787 element->numsinkpads--;
790 g_critical ("Removing pad without direction???");
793 element->pads = g_list_remove (element->pads, pad);
795 element->pads_cookie++;
796 GST_OBJECT_UNLOCK (element);
798 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
799 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
801 gst_object_unparent (GST_OBJECT_CAST (pad));
808 /* locking order is element > pad */
809 GST_OBJECT_UNLOCK (pad);
811 GST_OBJECT_LOCK (element);
812 GST_OBJECT_LOCK (pad);
813 g_critical ("Padname %s:%s does not belong to element %s when removing",
814 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
815 GST_OBJECT_UNLOCK (pad);
816 GST_OBJECT_UNLOCK (element);
822 * gst_element_no_more_pads:
823 * @element: a #GstElement
825 * Use this function to signal that the element does not expect any more pads
826 * to show up in the current pipeline. This function should be called whenever
827 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
828 * pad templates use this in combination with autopluggers to figure out that
829 * the element is done initializing its pads.
831 * This function emits the #GstElement::no-more-pads signal.
836 gst_element_no_more_pads (GstElement * element)
838 g_return_if_fail (GST_IS_ELEMENT (element));
840 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
844 pad_compare_name (GstPad * pad1, const gchar * name)
848 GST_OBJECT_LOCK (pad1);
849 result = strcmp (GST_PAD_NAME (pad1), name);
850 GST_OBJECT_UNLOCK (pad1);
856 * gst_element_get_static_pad:
857 * @element: a #GstElement to find a static pad of.
858 * @name: the name of the static #GstPad to retrieve.
860 * Retrieves a pad from @element by name. This version only retrieves
861 * already-existing (i.e. 'static') pads.
863 * Returns: (transfer full): the requested #GstPad if found, otherwise %NULL.
869 gst_element_get_static_pad (GstElement * element, const gchar * name)
872 GstPad *result = NULL;
874 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
875 g_return_val_if_fail (name != NULL, NULL);
877 GST_OBJECT_LOCK (element);
879 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
881 result = GST_PAD_CAST (find->data);
882 gst_object_ref (result);
885 if (result == NULL) {
886 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
887 name, GST_ELEMENT_NAME (element));
889 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
890 GST_ELEMENT_NAME (element), name);
892 GST_OBJECT_UNLOCK (element);
898 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
899 const gchar * name, const GstCaps * caps)
901 GstPad *newpad = NULL;
902 GstElementClass *oclass;
904 oclass = GST_ELEMENT_GET_CLASS (element);
906 #ifndef G_DISABLE_CHECKS
907 /* Some sanity checking here */
911 /* Is this the template name? */
912 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
913 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
915 const gchar *str, *data;
918 /* Otherwise check if it's a valid name for the name template */
919 str = strchr (templ->name_template, '%');
920 g_return_val_if_fail (str != NULL, NULL);
921 g_return_val_if_fail (strncmp (templ->name_template, name,
922 str - templ->name_template) == 0, NULL);
923 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
925 data = name + (str - templ->name_template);
927 /* Can either be %s or %d or %u, do sanity checking for %d */
928 if (*(str + 1) == 'd') {
932 tmp = g_ascii_strtoll (data, &endptr, 10);
933 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
934 && *endptr == '\0', NULL);
935 } else if (*(str + 1) == 'u') {
939 tmp = g_ascii_strtoull (data, &endptr, 10);
940 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
944 pad = gst_element_get_static_pad (element, name);
946 gst_object_unref (pad);
947 /* FIXME 0.11: Change this to g_return_val_if_fail() */
948 g_critical ("Element %s already has a pad named %s, the behaviour of "
949 " gst_element_get_request_pad() for existing pads is undefined!",
950 GST_ELEMENT_NAME (element), name);
955 if (oclass->request_new_pad)
956 newpad = (oclass->request_new_pad) (element, templ, name, caps);
959 gst_object_ref (newpad);
965 * gst_element_get_request_pad:
966 * @element: a #GstElement to find a request pad of.
967 * @name: the name of the request #GstPad to retrieve.
969 * Retrieves a pad from the element by name (e.g. "src_\%d"). This version only
970 * retrieves request pads. The pad should be released with
971 * gst_element_release_request_pad().
973 * This method is slow and will be deprecated in the future. New code should
974 * use gst_element_request_pad() with the requested template.
976 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
977 * Release after usage.
980 gst_element_get_request_pad (GstElement * element, const gchar * name)
982 GstPadTemplate *templ = NULL;
984 const gchar *req_name = NULL;
985 gboolean templ_found = FALSE;
988 gchar *str, *endptr = NULL;
989 GstElementClass *class;
991 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
992 g_return_val_if_fail (name != NULL, NULL);
994 class = GST_ELEMENT_GET_CLASS (element);
996 /* if the name contains a %, we assume it's the complete template name. Get
997 * the template and try to get a pad */
998 if (strstr (name, "%")) {
999 templ = gst_element_class_get_request_pad_template (class, name);
1004 /* there is no % in the name, try to find a matching template */
1005 list = class->padtemplates;
1006 while (!templ_found && list) {
1007 templ = (GstPadTemplate *) list->data;
1008 if (templ->presence == GST_PAD_REQUEST) {
1009 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1010 templ->name_template);
1011 /* see if we find an exact match */
1012 if (strcmp (name, templ->name_template) == 0) {
1017 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1018 and %d and %u, occurring at the end of the name_template, are the only
1020 else if ((str = strchr (templ->name_template, '%'))
1021 && strncmp (templ->name_template, name,
1022 str - templ->name_template) == 0
1023 && strlen (name) > str - templ->name_template) {
1024 data = name + (str - templ->name_template);
1025 if (*(str + 1) == 'd') {
1029 tmp = strtol (data, &endptr, 10);
1030 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1036 } else if (*(str + 1) == 'u') {
1040 tmp = strtoul (data, &endptr, 10);
1041 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1061 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1067 * gst_element_request_pad:
1068 * @element: a #GstElement to find a request pad of.
1069 * @templ: a #GstPadTemplate of which we want a pad of.
1070 * @name: (transfer none) (allow-none): the name of the request #GstPad
1071 * to retrieve. Can be %NULL.
1072 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1073 * request. Can be %NULL.
1075 * Retrieves a request pad from the element according to the provided template.
1076 * Pad templates can be looked up using
1077 * gst_element_factory_get_static_pad_templates().
1079 * The pad should be released with gst_element_release_request_pad().
1081 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1082 * Release after usage.
1085 gst_element_request_pad (GstElement * element,
1086 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1088 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1089 g_return_val_if_fail (templ != NULL, NULL);
1090 g_return_val_if_fail (templ->presence == GST_PAD_REQUEST, NULL);
1092 return _gst_element_request_pad (element, templ, name, caps);
1095 static GstIterator *
1096 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1098 GstIterator *result;
1100 GST_OBJECT_LOCK (element);
1101 result = gst_iterator_new_list (GST_TYPE_PAD,
1102 GST_OBJECT_GET_LOCK (element),
1103 &element->pads_cookie, padlist, (GObject *) element, NULL);
1104 GST_OBJECT_UNLOCK (element);
1110 * gst_element_iterate_pads:
1111 * @element: a #GstElement to iterate pads of.
1113 * Retrieves an iterator of @element's pads. The iterator should
1114 * be freed after usage. Also more specialized iterators exists such as
1115 * gst_element_iterate_src_pads() or gst_element_iterate_sink_pads().
1117 * The order of pads returned by the iterator will be the order in which
1118 * the pads were added to the element.
1120 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1126 gst_element_iterate_pads (GstElement * element)
1128 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1130 return gst_element_iterate_pad_list (element, &element->pads);
1134 * gst_element_iterate_src_pads:
1135 * @element: a #GstElement.
1137 * Retrieves an iterator of @element's source pads.
1139 * The order of pads returned by the iterator will be the order in which
1140 * the pads were added to the element.
1142 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1148 gst_element_iterate_src_pads (GstElement * element)
1150 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1152 return gst_element_iterate_pad_list (element, &element->srcpads);
1156 * gst_element_iterate_sink_pads:
1157 * @element: a #GstElement.
1159 * Retrieves an iterator of @element's sink pads.
1161 * The order of pads returned by the iterator will be the order in which
1162 * the pads were added to the element.
1164 * Returns: (transfer full): the #GstIterator of #GstPad. Unref each pad
1170 gst_element_iterate_sink_pads (GstElement * element)
1172 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1174 return gst_element_iterate_pad_list (element, &element->sinkpads);
1178 * gst_element_class_add_pad_template:
1179 * @klass: the #GstElementClass to add the pad template to.
1180 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1182 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1183 * functions of classes. If a pad template with the same name as an already
1184 * existing one is added the old one is replaced by the new one.
1188 gst_element_class_add_pad_template (GstElementClass * klass,
1189 GstPadTemplate * templ)
1191 GList *template_list = klass->padtemplates;
1193 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1194 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1196 /* If we already have a pad template with the same name replace the
1198 while (template_list) {
1199 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1201 /* Found pad with the same name, replace and return */
1202 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1203 gst_object_unref (padtempl);
1204 template_list->data = templ;
1207 template_list = g_list_next (template_list);
1210 /* Take ownership of the floating ref */
1211 gst_object_ref_sink (templ);
1213 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1214 klass->numpadtemplates++;
1218 * gst_element_class_add_metadata:
1219 * @klass: class to set metadata for
1220 * @key: the key to set
1221 * @value: the value to set
1223 * Set @key with @value as metadata in @klass.
1226 gst_element_class_add_metadata (GstElementClass * klass,
1227 const gchar * key, const gchar * value)
1229 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1230 g_return_if_fail (key != NULL);
1231 g_return_if_fail (value != NULL);
1233 gst_structure_set ((GstStructure *) klass->metadata,
1234 key, G_TYPE_STRING, value, NULL);
1238 * gst_element_class_add_static_metadata:
1239 * @klass: class to set metadata for
1240 * @key: the key to set
1241 * @value: the value to set
1243 * Set @key with @value as metadata in @klass.
1245 * Same as gst_element_class_add_metadata(), but @value must be a static string
1246 * or an inlined string, as it will not be copied. (GStreamer plugins will
1247 * be made resident once loaded, so this function can be used even from
1248 * dynamically loaded plugins.)
1251 gst_element_class_add_static_metadata (GstElementClass * klass,
1252 const gchar * key, const gchar * value)
1254 GValue val = G_VALUE_INIT;
1256 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1257 g_return_if_fail (key != NULL);
1258 g_return_if_fail (value != NULL);
1260 g_value_init (&val, G_TYPE_STRING);
1261 g_value_set_static_string (&val, value);
1262 gst_structure_take_value ((GstStructure *) klass->metadata, key, &val);
1266 * gst_element_class_set_metadata:
1267 * @klass: class to set metadata for
1268 * @longname: The long English name of the element. E.g. "File Sink"
1269 * @classification: String describing the type of element, as an unordered list
1270 * separated with slashes ('/'). See draft-klass.txt of the design docs
1271 * for more details and common types. E.g: "Sink/File"
1272 * @description: Sentence describing the purpose of the element.
1273 * E.g: "Write stream to a file"
1274 * @author: Name and contact details of the author(s). Use \n to separate
1275 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1277 * Sets the detailed information for a #GstElementClass.
1278 * <note>This function is for use in _class_init functions only.</note>
1281 gst_element_class_set_metadata (GstElementClass * klass,
1282 const gchar * longname, const gchar * classification,
1283 const gchar * description, const gchar * author)
1285 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1287 gst_structure_id_set ((GstStructure *) klass->metadata,
1288 GST_QUARK (ELEMENT_METADATA_LONGNAME), G_TYPE_STRING, longname,
1289 GST_QUARK (ELEMENT_METADATA_KLASS), G_TYPE_STRING, classification,
1290 GST_QUARK (ELEMENT_METADATA_DESCRIPTION), G_TYPE_STRING, description,
1291 GST_QUARK (ELEMENT_METADATA_AUTHOR), G_TYPE_STRING, author, NULL);
1295 * gst_element_class_set_static_metadata:
1296 * @klass: class to set metadata for
1297 * @longname: The long English name of the element. E.g. "File Sink"
1298 * @classification: String describing the type of element, as an unordered list
1299 * separated with slashes ('/'). See draft-klass.txt of the design docs
1300 * for more details and common types. E.g: "Sink/File"
1301 * @description: Sentence describing the purpose of the element.
1302 * E.g: "Write stream to a file"
1303 * @author: Name and contact details of the author(s). Use \n to separate
1304 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1306 * Sets the detailed information for a #GstElementClass.
1307 * <note>This function is for use in _class_init functions only.</note>
1309 * Same as gst_element_class_set_metadata(), but @longname, @classification,
1310 * @description, and @author must be static strings or inlined strings, as
1311 * they will not be copied. (GStreamer plugins will be made resident once
1312 * loaded, so this function can be used even from dynamically loaded plugins.)
1315 gst_element_class_set_static_metadata (GstElementClass * klass,
1316 const gchar * longname, const gchar * classification,
1317 const gchar * description, const gchar * author)
1319 GstStructure *s = (GstStructure *) klass->metadata;
1320 GValue val = G_VALUE_INIT;
1322 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1324 g_value_init (&val, G_TYPE_STRING);
1326 g_value_set_static_string (&val, longname);
1327 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_LONGNAME), &val);
1329 g_value_set_static_string (&val, classification);
1330 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_KLASS), &val);
1332 g_value_set_static_string (&val, description);
1333 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_DESCRIPTION),
1336 g_value_set_static_string (&val, author);
1337 gst_structure_id_take_value (s, GST_QUARK (ELEMENT_METADATA_AUTHOR), &val);
1341 * gst_element_class_get_metadata:
1342 * @klass: class to get metadata for
1343 * @key: the key to get
1345 * Get metadata with @key in @klass.
1347 * Returns: the metadata for @key.
1350 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1352 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1353 g_return_val_if_fail (key != NULL, NULL);
1355 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1359 * gst_element_class_get_pad_template_list:
1360 * @element_class: a #GstElementClass to get pad templates of.
1362 * Retrieves a list of the pad templates associated with @element_class. The
1363 * list must not be modified by the calling code.
1364 * <note>If you use this function in the #GInstanceInitFunc of an object class
1365 * that has subclasses, make sure to pass the g_class parameter of the
1366 * #GInstanceInitFunc here.</note>
1368 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1372 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1374 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1376 return element_class->padtemplates;
1380 * gst_element_class_get_pad_template:
1381 * @element_class: a #GstElementClass to get the pad template of.
1382 * @name: the name of the #GstPadTemplate to get.
1384 * Retrieves a padtemplate from @element_class with the given name.
1385 * <note>If you use this function in the #GInstanceInitFunc of an object class
1386 * that has subclasses, make sure to pass the g_class parameter of the
1387 * #GInstanceInitFunc here.</note>
1389 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1390 * if none was found. No unreferencing is necessary.
1393 gst_element_class_get_pad_template (GstElementClass *
1394 element_class, const gchar * name)
1398 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1399 g_return_val_if_fail (name != NULL, NULL);
1401 padlist = element_class->padtemplates;
1404 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1406 if (strcmp (padtempl->name_template, name) == 0)
1409 padlist = g_list_next (padlist);
1415 static GstPadTemplate *
1416 gst_element_class_get_request_pad_template (GstElementClass *
1417 element_class, const gchar * name)
1419 GstPadTemplate *tmpl;
1421 tmpl = gst_element_class_get_pad_template (element_class, name);
1422 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1428 /* get a random pad on element of the given direction.
1429 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1432 gst_element_get_random_pad (GstElement * element,
1433 gboolean need_linked, GstPadDirection dir)
1435 GstPad *result = NULL;
1438 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1442 GST_OBJECT_LOCK (element);
1443 pads = element->srcpads;
1446 GST_OBJECT_LOCK (element);
1447 pads = element->sinkpads;
1450 goto wrong_direction;
1452 for (; pads; pads = g_list_next (pads)) {
1453 GstPad *pad = GST_PAD_CAST (pads->data);
1455 GST_OBJECT_LOCK (pad);
1456 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1457 GST_DEBUG_PAD_NAME (pad));
1459 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1460 /* if we require a linked pad, and it is not linked, continue the
1462 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1463 GST_DEBUG_PAD_NAME (pad));
1464 GST_OBJECT_UNLOCK (pad);
1467 /* found a pad, stop search */
1468 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1469 GST_DEBUG_PAD_NAME (pad));
1470 GST_OBJECT_UNLOCK (pad);
1476 gst_object_ref (result);
1478 GST_OBJECT_UNLOCK (element);
1482 /* ERROR handling */
1485 g_warning ("unknown pad direction %d", dir);
1491 gst_element_default_send_event (GstElement * element, GstEvent * event)
1493 gboolean result = FALSE;
1496 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1497 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1498 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1501 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1502 "pushing %s event to random %s pad %s:%s",
1503 GST_EVENT_TYPE_NAME (event),
1504 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1505 GST_DEBUG_PAD_NAME (pad));
1507 result = gst_pad_push_event (pad, event);
1508 gst_object_unref (pad);
1510 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1511 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1512 gst_event_unref (event);
1518 * gst_element_send_event:
1519 * @element: a #GstElement to send the event to.
1520 * @event: (transfer full): the #GstEvent to send to the element.
1522 * Sends an event to an element. If the element doesn't implement an
1523 * event handler, the event will be pushed on a random linked sink pad for
1524 * upstream events or a random linked source pad for downstream events.
1526 * This function takes owership of the provided event so you should
1527 * gst_event_ref() it if you want to reuse the event after this call.
1531 * Returns: %TRUE if the event was handled. Events that trigger a preroll (such
1532 * as flushing seeks and steps) will emit %GST_MESSAGE_ASYNC_DONE.
1535 gst_element_send_event (GstElement * element, GstEvent * event)
1537 GstElementClass *oclass;
1538 gboolean result = FALSE;
1540 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1541 g_return_val_if_fail (event != NULL, FALSE);
1543 oclass = GST_ELEMENT_GET_CLASS (element);
1545 GST_STATE_LOCK (element);
1546 if (oclass->send_event) {
1547 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1548 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1549 result = oclass->send_event (element, event);
1551 GST_STATE_UNLOCK (element);
1558 * @element: a #GstElement to send the event to.
1559 * @rate: The new playback rate
1560 * @format: The format of the seek values
1561 * @flags: The optional seek flags.
1562 * @start_type: The type and flags for the new start position
1563 * @start: The value of the new start position
1564 * @stop_type: The type and flags for the new stop position
1565 * @stop: The value of the new stop position
1567 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1568 * the parameters. The seek event is sent to the element using
1569 * gst_element_send_event().
1573 * Returns: %TRUE if the event was handled. Flushing seeks will trigger a
1574 * preroll, which will emit %GST_MESSAGE_ASYNC_DONE.
1577 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1578 GstSeekFlags flags, GstSeekType start_type, gint64 start,
1579 GstSeekType stop_type, gint64 stop)
1584 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1587 gst_event_new_seek (rate, format, flags, start_type, start, stop_type,
1589 result = gst_element_send_event (element, event);
1595 gst_element_default_query (GstElement * element, GstQuery * query)
1597 gboolean result = FALSE;
1600 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1602 result = gst_pad_query (pad, query);
1604 gst_object_unref (pad);
1606 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1608 GstPad *peer = gst_pad_get_peer (pad);
1611 result = gst_pad_query (peer, query);
1613 gst_object_unref (peer);
1615 gst_object_unref (pad);
1622 * gst_element_query:
1623 * @element: a #GstElement to perform the query on.
1624 * @query: (transfer none): the #GstQuery.
1626 * Performs a query on the given element.
1628 * For elements that don't implement a query handler, this function
1629 * forwards the query to a random srcpad or to the peer of a
1630 * random linked sinkpad of this element.
1632 * Please note that some queries might need a running pipeline to work.
1634 * Returns: TRUE if the query could be performed.
1639 gst_element_query (GstElement * element, GstQuery * query)
1641 GstElementClass *oclass;
1642 gboolean result = FALSE;
1644 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1645 g_return_val_if_fail (query != NULL, FALSE);
1647 oclass = GST_ELEMENT_GET_CLASS (element);
1649 if (oclass->query) {
1650 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1651 GST_ELEMENT_NAME (element));
1652 result = oclass->query (element, query);
1658 * gst_element_post_message:
1659 * @element: a #GstElement posting the message
1660 * @message: (transfer full): a #GstMessage to post
1662 * Post a message on the element's #GstBus. This function takes ownership of the
1663 * message; if you want to access the message after this call, you should add an
1664 * additional reference before calling.
1666 * Returns: %TRUE if the message was successfully posted. The function returns
1667 * %FALSE if the element did not have a bus.
1672 gst_element_post_message (GstElement * element, GstMessage * message)
1675 gboolean result = FALSE;
1677 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1678 g_return_val_if_fail (message != NULL, FALSE);
1680 GST_OBJECT_LOCK (element);
1683 if (G_UNLIKELY (bus == NULL))
1686 gst_object_ref (bus);
1687 GST_OBJECT_UNLOCK (element);
1689 /* we release the element lock when posting the message so that any
1690 * (synchronous) message handlers can operate on the element */
1691 result = gst_bus_post (bus, message);
1692 gst_object_unref (bus);
1699 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1700 "not posting message %p: no bus", message);
1701 GST_OBJECT_UNLOCK (element);
1702 gst_message_unref (message);
1708 * _gst_element_error_printf:
1709 * @format: the printf-like format to use, or %NULL
1711 * This function is only used internally by the gst_element_error() macro.
1713 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1719 _gst_element_error_printf (const gchar * format, ...)
1729 va_start (args, format);
1730 buffer = g_strdup_vprintf (format, args);
1736 * gst_element_message_full:
1737 * @element: a #GstElement to send message from
1738 * @type: the #GstMessageType
1739 * @domain: the GStreamer GError domain this message belongs to
1740 * @code: the GError code belonging to the domain
1741 * @text: (allow-none) (transfer full): an allocated text string to be used
1742 * as a replacement for the default message connected to code,
1744 * @debug: (allow-none) (transfer full): an allocated debug message to be
1745 * used as a replacement for the default debugging information,
1747 * @file: the source code file where the error was generated
1748 * @function: the source code function where the error was generated
1749 * @line: the source code line where the error was generated
1751 * Post an error, warning or info message on the bus from inside an element.
1753 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1754 * #GST_MESSAGE_INFO.
1758 void gst_element_message_full
1759 (GstElement * element, GstMessageType type,
1760 GQuark domain, gint code, gchar * text,
1761 gchar * debug, const gchar * file, const gchar * function, gint line)
1763 GError *gerror = NULL;
1767 gboolean has_debug = TRUE;
1768 GstMessage *message = NULL;
1771 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1772 g_return_if_fail (GST_IS_ELEMENT (element));
1773 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1774 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1776 /* check if we send the given text or the default error text */
1777 if ((text == NULL) || (text[0] == 0)) {
1778 /* text could have come from g_strdup_printf (""); */
1780 sent_text = gst_error_get_message (domain, code);
1784 /* construct a sent_debug with extra information from source */
1785 if ((debug == NULL) || (debug[0] == 0)) {
1786 /* debug could have come from g_strdup_printf (""); */
1790 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1792 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1793 file, line, function, name, debug);
1795 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1796 file, line, function, name);
1800 /* create gerror and post message */
1801 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1803 gerror = g_error_new_literal (domain, code, sent_text);
1806 case GST_MESSAGE_ERROR:
1808 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1810 case GST_MESSAGE_WARNING:
1811 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1814 case GST_MESSAGE_INFO:
1815 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1819 g_assert_not_reached ();
1822 gst_element_post_message (element, message);
1824 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1825 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1828 g_error_free (gerror);
1829 g_free (sent_debug);
1834 * gst_element_is_locked_state:
1835 * @element: a #GstElement.
1837 * Checks if the state of an element is locked.
1838 * If the state of an element is locked, state changes of the parent don't
1839 * affect the element.
1840 * This way you can leave currently unused elements inside bins. Just lock their
1841 * state before changing the state from #GST_STATE_NULL.
1845 * Returns: TRUE, if the element's state is locked.
1848 gst_element_is_locked_state (GstElement * element)
1852 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1854 GST_OBJECT_LOCK (element);
1855 result = GST_ELEMENT_IS_LOCKED_STATE (element);
1856 GST_OBJECT_UNLOCK (element);
1862 * gst_element_set_locked_state:
1863 * @element: a #GstElement
1864 * @locked_state: TRUE to lock the element's state
1866 * Locks the state of an element, so state changes of the parent don't affect
1867 * this element anymore.
1871 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1872 * or the elements state-locking needed no change.
1875 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1879 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1881 GST_OBJECT_LOCK (element);
1882 old = GST_ELEMENT_IS_LOCKED_STATE (element);
1884 if (G_UNLIKELY (old == locked_state))
1888 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1889 GST_ELEMENT_NAME (element));
1890 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1892 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1893 GST_ELEMENT_NAME (element));
1894 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1896 GST_OBJECT_UNLOCK (element);
1902 GST_CAT_DEBUG (GST_CAT_STATES,
1903 "elements %s was already in locked state %d",
1904 GST_ELEMENT_NAME (element), old);
1905 GST_OBJECT_UNLOCK (element);
1912 * gst_element_sync_state_with_parent:
1913 * @element: a #GstElement.
1915 * Tries to change the state of the element to the same as its parent.
1916 * If this function returns FALSE, the state of element is undefined.
1918 * Returns: TRUE, if the element's state could be synced to the parent's state.
1923 gst_element_sync_state_with_parent (GstElement * element)
1927 GstStateChangeReturn ret;
1929 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1931 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1932 GstState parent_current, parent_pending;
1934 GST_OBJECT_LOCK (parent);
1935 parent_current = GST_STATE (parent);
1936 parent_pending = GST_STATE_PENDING (parent);
1937 GST_OBJECT_UNLOCK (parent);
1939 /* set to pending if there is one, else we set it to the current state of
1941 if (parent_pending != GST_STATE_VOID_PENDING)
1942 target = parent_pending;
1944 target = parent_current;
1946 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1947 "syncing state (%s) to parent %s %s (%s, %s)",
1948 gst_element_state_get_name (GST_STATE (element)),
1949 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1950 gst_element_state_get_name (parent_current),
1951 gst_element_state_get_name (parent_pending));
1953 ret = gst_element_set_state (element, target);
1954 if (ret == GST_STATE_CHANGE_FAILURE)
1957 gst_object_unref (parent);
1961 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
1968 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1969 "syncing state failed (%s)",
1970 gst_element_state_change_return_get_name (ret));
1971 gst_object_unref (parent);
1977 static GstStateChangeReturn
1978 gst_element_get_state_func (GstElement * element,
1979 GstState * state, GstState * pending, GstClockTime timeout)
1981 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
1982 GstState old_pending;
1984 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
1985 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
1987 GST_OBJECT_LOCK (element);
1988 ret = GST_STATE_RETURN (element);
1989 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
1990 gst_element_state_change_return_get_name (ret));
1992 /* we got an error, report immediately */
1993 if (ret == GST_STATE_CHANGE_FAILURE)
1996 /* we got no_preroll, report immediately */
1997 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2000 /* no need to wait async if we are not async */
2001 if (ret != GST_STATE_CHANGE_ASYNC)
2004 old_pending = GST_STATE_PENDING (element);
2005 if (old_pending != GST_STATE_VOID_PENDING) {
2009 /* get cookie to detect state changes during waiting */
2010 cookie = element->state_cookie;
2012 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2013 "waiting for element to commit state");
2015 /* we have a pending state change, wait for it to complete */
2016 if (timeout != GST_CLOCK_TIME_NONE) {
2018 /* make timeout absolute */
2019 end_time = g_get_monotonic_time () + (timeout / 1000);
2020 signaled = GST_STATE_WAIT_UNTIL (element, end_time);
2022 GST_STATE_WAIT (element);
2027 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2028 /* timeout triggered */
2029 ret = GST_STATE_CHANGE_ASYNC;
2031 if (cookie != element->state_cookie)
2034 /* could be success or failure */
2035 if (old_pending == GST_STATE (element)) {
2036 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2037 ret = GST_STATE_CHANGE_SUCCESS;
2039 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2040 ret = GST_STATE_CHANGE_FAILURE;
2043 /* if nothing is pending anymore we can return SUCCESS */
2044 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2045 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2046 ret = GST_STATE_CHANGE_SUCCESS;
2052 *state = GST_STATE (element);
2054 *pending = GST_STATE_PENDING (element);
2056 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2057 "state current: %s, pending: %s, result: %s",
2058 gst_element_state_get_name (GST_STATE (element)),
2059 gst_element_state_get_name (GST_STATE_PENDING (element)),
2060 gst_element_state_change_return_get_name (ret));
2061 GST_OBJECT_UNLOCK (element);
2068 *state = GST_STATE_VOID_PENDING;
2070 *pending = GST_STATE_VOID_PENDING;
2072 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2074 GST_OBJECT_UNLOCK (element);
2076 return GST_STATE_CHANGE_FAILURE;
2081 * gst_element_get_state:
2082 * @element: a #GstElement to get the state of.
2083 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2085 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2086 * state. Can be %NULL.
2087 * @timeout: a #GstClockTime to specify the timeout for an async
2088 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2090 * Gets the state of the element.
2092 * For elements that performed an ASYNC state change, as reported by
2093 * gst_element_set_state(), this function will block up to the
2094 * specified timeout value for the state change to complete.
2095 * If the element completes the state change or goes into
2096 * an error, this function returns immediately with a return value of
2097 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2099 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2100 * returns the current and pending state immediately.
2102 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2103 * successfully changed its state but is not able to provide data yet.
2104 * This mostly happens for live sources that only produce data in
2105 * %GST_STATE_PLAYING. While the state change return is equivalent to
2106 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2107 * some sink elements might not be able to complete their state change because
2108 * an element is not producing data to complete the preroll. When setting the
2109 * element to playing, the preroll will complete and playback will start.
2111 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2112 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2113 * element is still performing a state change or
2114 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2118 GstStateChangeReturn
2119 gst_element_get_state (GstElement * element,
2120 GstState * state, GstState * pending, GstClockTime timeout)
2122 GstElementClass *oclass;
2123 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2125 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2127 oclass = GST_ELEMENT_GET_CLASS (element);
2129 if (oclass->get_state)
2130 result = (oclass->get_state) (element, state, pending, timeout);
2136 * gst_element_abort_state:
2137 * @element: a #GstElement to abort the state of.
2139 * Abort the state change of the element. This function is used
2140 * by elements that do asynchronous state changes and find out
2141 * something is wrong.
2143 * This function should be called with the STATE_LOCK held.
2148 gst_element_abort_state (GstElement * element)
2152 #ifndef GST_DISABLE_GST_DEBUG
2156 g_return_if_fail (GST_IS_ELEMENT (element));
2158 GST_OBJECT_LOCK (element);
2159 pending = GST_STATE_PENDING (element);
2161 if (pending == GST_STATE_VOID_PENDING ||
2162 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2163 goto nothing_aborted;
2165 #ifndef GST_DISABLE_GST_DEBUG
2166 old_state = GST_STATE (element);
2168 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2169 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2170 gst_element_state_get_name (pending));
2174 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2176 GST_STATE_BROADCAST (element);
2177 GST_OBJECT_UNLOCK (element);
2183 GST_OBJECT_UNLOCK (element);
2188 /* Not static because GstBin has manual state handling too */
2190 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2191 GstState newstate, GstState pending)
2193 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2194 GstMessage *message;
2196 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2197 "notifying about state-changed %s to %s (%s pending)",
2198 gst_element_state_get_name (oldstate),
2199 gst_element_state_get_name (newstate),
2200 gst_element_state_get_name (pending));
2202 if (klass->state_changed)
2203 klass->state_changed (element, oldstate, newstate, pending);
2205 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2206 oldstate, newstate, pending);
2207 gst_element_post_message (element, message);
2211 * gst_element_continue_state:
2212 * @element: a #GstElement to continue the state change of.
2213 * @ret: The previous state return value
2215 * Commit the state change of the element and proceed to the next
2216 * pending state if any. This function is used
2217 * by elements that do asynchronous state changes.
2218 * The core will normally call this method automatically when an
2219 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2221 * If after calling this method the element still has not reached
2222 * the pending state, the next state change is performed.
2224 * This method is used internally and should normally not be called by plugins
2227 * Returns: The result of the commit state change.
2231 GstStateChangeReturn
2232 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2234 GstStateChangeReturn old_ret;
2235 GstState old_state, old_next;
2236 GstState current, next, pending;
2237 GstStateChange transition;
2239 GST_OBJECT_LOCK (element);
2240 old_ret = GST_STATE_RETURN (element);
2241 GST_STATE_RETURN (element) = ret;
2242 pending = GST_STATE_PENDING (element);
2244 /* check if there is something to commit */
2245 if (pending == GST_STATE_VOID_PENDING)
2246 goto nothing_pending;
2248 old_state = GST_STATE (element);
2249 /* this is the state we should go to next */
2250 old_next = GST_STATE_NEXT (element);
2251 /* update current state */
2252 current = GST_STATE (element) = old_next;
2254 /* see if we reached the final state */
2255 if (pending == current)
2258 next = GST_STATE_GET_NEXT (current, pending);
2259 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2261 GST_STATE_NEXT (element) = next;
2263 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2264 GST_OBJECT_UNLOCK (element);
2266 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2267 "committing state from %s to %s, pending %s, next %s",
2268 gst_element_state_get_name (old_state),
2269 gst_element_state_get_name (old_next),
2270 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2272 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2274 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2275 "continue state change %s to %s, final %s",
2276 gst_element_state_get_name (current),
2277 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2279 ret = gst_element_change_state (element, transition);
2285 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2286 GST_OBJECT_UNLOCK (element);
2291 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2292 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2294 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2295 "completed state change to %s", gst_element_state_get_name (pending));
2296 GST_OBJECT_UNLOCK (element);
2298 /* don't post silly messages with the same state. This can happen
2299 * when an element state is changed to what it already was. For bins
2300 * this can be the result of a lost state, which we check with the
2301 * previous return value.
2302 * We do signal the cond though as a _get_state() might be blocking
2304 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2305 _priv_gst_element_state_changed (element, old_state, old_next,
2306 GST_STATE_VOID_PENDING);
2308 GST_STATE_BROADCAST (element);
2315 * gst_element_lost_state:
2316 * @element: a #GstElement the state is lost of
2318 * Brings the element to the lost state. The current state of the
2319 * element is copied to the pending state so that any call to
2320 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2322 * An ASYNC_START message is posted. If the element was PLAYING, it will
2323 * go to PAUSED. The element will be restored to its PLAYING state by
2324 * the parent pipeline when it prerolls again.
2326 * This is mostly used for elements that lost their preroll buffer
2327 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2328 * they will go to their pending state again when a new preroll buffer is
2329 * queued. This function can only be called when the element is currently
2330 * not in error or an async state change.
2332 * This function is used internally and should normally not be called from
2333 * plugins or applications.
2336 gst_element_lost_state (GstElement * element)
2338 GstState old_state, new_state;
2339 GstMessage *message;
2341 g_return_if_fail (GST_IS_ELEMENT (element));
2343 GST_OBJECT_LOCK (element);
2344 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2347 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2348 goto only_async_start;
2350 old_state = GST_STATE (element);
2352 /* when we were PLAYING, the new state is PAUSED. We will also not
2353 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2354 * when we preroll. */
2355 if (old_state > GST_STATE_PAUSED)
2356 new_state = GST_STATE_PAUSED;
2358 new_state = old_state;
2360 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2361 "lost state of %s to %s", gst_element_state_get_name (old_state),
2362 gst_element_state_get_name (new_state));
2364 GST_STATE (element) = new_state;
2365 GST_STATE_NEXT (element) = new_state;
2366 GST_STATE_PENDING (element) = new_state;
2367 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2368 GST_OBJECT_UNLOCK (element);
2370 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2372 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2373 gst_element_post_message (element, message);
2379 GST_OBJECT_UNLOCK (element);
2384 GST_OBJECT_UNLOCK (element);
2386 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2387 gst_element_post_message (element, message);
2393 * gst_element_set_state:
2394 * @element: a #GstElement to change state of.
2395 * @state: the element's new #GstState.
2397 * Sets the state of the element. This function will try to set the
2398 * requested state by going through all the intermediary states and calling
2399 * the class's state change function for each.
2401 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2402 * element will perform the remainder of the state change asynchronously in
2404 * An application can use gst_element_get_state() to wait for the completion
2405 * of the state change or it can wait for a state change message on the bus.
2407 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2408 * #GST_STATE_CHANGE_ASYNC.
2410 * Returns: Result of the state change using #GstStateChangeReturn.
2414 GstStateChangeReturn
2415 gst_element_set_state (GstElement * element, GstState state)
2417 GstElementClass *oclass;
2418 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2420 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2422 oclass = GST_ELEMENT_GET_CLASS (element);
2424 if (oclass->set_state)
2425 result = (oclass->set_state) (element, state);
2431 * default set state function, calculates the next state based
2432 * on current state and calls the change_state function
2434 static GstStateChangeReturn
2435 gst_element_set_state_func (GstElement * element, GstState state)
2437 GstState current, next, old_pending;
2438 GstStateChangeReturn ret;
2439 GstStateChange transition;
2440 GstStateChangeReturn old_ret;
2442 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2444 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2445 gst_element_state_get_name (state));
2447 /* state lock is taken to protect the set_state() and get_state()
2448 * procedures, it does not lock any variables. */
2449 GST_STATE_LOCK (element);
2451 /* now calculate how to get to the new state */
2452 GST_OBJECT_LOCK (element);
2453 old_ret = GST_STATE_RETURN (element);
2454 /* previous state change returned an error, remove all pending
2455 * and next states */
2456 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2457 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2458 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2459 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2462 current = GST_STATE (element);
2463 next = GST_STATE_NEXT (element);
2464 old_pending = GST_STATE_PENDING (element);
2466 /* this is the (new) state we should go to. TARGET is the last state we set on
2468 if (state != GST_STATE_TARGET (element)) {
2469 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2470 "setting target state to %s", gst_element_state_get_name (state));
2471 GST_STATE_TARGET (element) = state;
2472 /* increment state cookie so that we can track each state change. We only do
2473 * this if this is actually a new state change. */
2474 element->state_cookie++;
2476 GST_STATE_PENDING (element) = state;
2478 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2479 "current %s, old_pending %s, next %s, old return %s",
2480 gst_element_state_get_name (current),
2481 gst_element_state_get_name (old_pending),
2482 gst_element_state_get_name (next),
2483 gst_element_state_change_return_get_name (old_ret));
2485 /* if the element was busy doing a state change, we just update the
2486 * target state, it'll get to it async then. */
2487 if (old_pending != GST_STATE_VOID_PENDING) {
2488 /* upwards state change will happen ASYNC */
2489 if (old_pending <= state)
2491 /* element is going to this state already */
2492 else if (next == state)
2494 /* element was performing an ASYNC upward state change and
2495 * we request to go downward again. Start from the next pending
2497 else if (next > state
2498 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2502 next = GST_STATE_GET_NEXT (current, state);
2503 /* now we store the next state */
2504 GST_STATE_NEXT (element) = next;
2505 /* mark busy, we need to check that there is actually a state change
2506 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2507 * the default element change_state function has no way to know what the
2508 * old value was... could consider this a FIXME...*/
2509 if (current != next)
2510 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2512 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2514 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2515 "%s: setting state from %s to %s",
2516 (next != state ? "intermediate" : "final"),
2517 gst_element_state_get_name (current), gst_element_state_get_name (next));
2519 /* now signal any waiters, they will error since the cookie was incremented */
2520 GST_STATE_BROADCAST (element);
2522 GST_OBJECT_UNLOCK (element);
2524 ret = gst_element_change_state (element, transition);
2526 GST_STATE_UNLOCK (element);
2528 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2529 gst_element_state_change_return_get_name (ret));
2535 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2536 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2537 "element was busy with async state change");
2538 GST_OBJECT_UNLOCK (element);
2540 GST_STATE_UNLOCK (element);
2542 return GST_STATE_CHANGE_ASYNC;
2547 * gst_element_change_state:
2548 * @element: a #GstElement
2549 * @transition: the requested transition
2551 * Perform @transition on @element.
2553 * This function must be called with STATE_LOCK held and is mainly used
2556 * Returns: the #GstStateChangeReturn of the state transition.
2558 GstStateChangeReturn
2559 gst_element_change_state (GstElement * element, GstStateChange transition)
2561 GstElementClass *oclass;
2562 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2564 oclass = GST_ELEMENT_GET_CLASS (element);
2566 /* call the state change function so it can set the state */
2567 if (oclass->change_state)
2568 ret = (oclass->change_state) (element, transition);
2570 ret = GST_STATE_CHANGE_FAILURE;
2573 case GST_STATE_CHANGE_FAILURE:
2574 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2575 "have FAILURE change_state return");
2576 /* state change failure */
2577 gst_element_abort_state (element);
2579 case GST_STATE_CHANGE_ASYNC:
2583 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2584 "element will change state ASYNC");
2586 target = GST_STATE_TARGET (element);
2588 if (target > GST_STATE_READY)
2591 /* else we just continue the state change downwards */
2592 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2593 "forcing commit state %s <= %s",
2594 gst_element_state_get_name (target),
2595 gst_element_state_get_name (GST_STATE_READY));
2597 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2600 case GST_STATE_CHANGE_SUCCESS:
2601 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2602 "element changed state SUCCESS");
2603 /* we can commit the state now which will proceeed to
2605 ret = gst_element_continue_state (element, ret);
2607 case GST_STATE_CHANGE_NO_PREROLL:
2608 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2609 "element changed state NO_PREROLL");
2610 /* we can commit the state now which will proceeed to
2612 ret = gst_element_continue_state (element, ret);
2615 goto invalid_return;
2618 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2623 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2631 GST_OBJECT_LOCK (element);
2632 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2633 g_critical ("%s: unknown return value %d from a state change function",
2634 GST_ELEMENT_NAME (element), ret);
2636 /* we are in error now */
2637 ret = GST_STATE_CHANGE_FAILURE;
2638 GST_STATE_RETURN (element) = ret;
2639 GST_OBJECT_UNLOCK (element);
2645 /* gst_iterator_fold functions for pads_activate
2646 * Stop the iterator if activating one pad failed. */
2648 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2650 GstPad *pad = g_value_get_object (vpad);
2651 gboolean cont = TRUE;
2653 if (!(cont = gst_pad_set_active (pad, *active)))
2654 g_value_set_boolean (ret, FALSE);
2659 /* returns false on error or early cutout of the fold, true if all
2660 * pads in @iter were (de)activated successfully. */
2662 iterator_activate_fold_with_resync (GstIterator * iter,
2663 GstIteratorFoldFunction func, gpointer user_data)
2665 GstIteratorResult ires;
2668 /* no need to unset this later, it's just a boolean */
2669 g_value_init (&ret, G_TYPE_BOOLEAN);
2670 g_value_set_boolean (&ret, TRUE);
2673 ires = gst_iterator_fold (iter, func, &ret, user_data);
2675 case GST_ITERATOR_RESYNC:
2676 /* need to reset the result again */
2677 g_value_set_boolean (&ret, TRUE);
2678 gst_iterator_resync (iter);
2680 case GST_ITERATOR_DONE:
2681 /* all pads iterated, return collected value */
2684 /* iterator returned _ERROR or premature end with _OK,
2685 * mark an error and exit */
2686 g_value_set_boolean (&ret, FALSE);
2691 /* return collected value */
2692 return g_value_get_boolean (&ret);
2695 /* is called with STATE_LOCK
2697 * Pads are activated from source pads to sinkpads.
2700 gst_element_pads_activate (GstElement * element, gboolean active)
2705 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2706 "%s pads", active ? "activate" : "deactivate");
2708 iter = gst_element_iterate_src_pads (element);
2710 iterator_activate_fold_with_resync (iter,
2711 (GstIteratorFoldFunction) activate_pads, &active);
2712 gst_iterator_free (iter);
2713 if (G_UNLIKELY (!res))
2716 iter = gst_element_iterate_sink_pads (element);
2718 iterator_activate_fold_with_resync (iter,
2719 (GstIteratorFoldFunction) activate_pads, &active);
2720 gst_iterator_free (iter);
2721 if (G_UNLIKELY (!res))
2724 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2725 "pad %sactivation successful", active ? "" : "de");
2732 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2733 "pad %sactivation failed", active ? "" : "de");
2738 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2739 "sink pads_activate failed");
2744 /* is called with STATE_LOCK */
2745 static GstStateChangeReturn
2746 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2748 GstState state, next;
2749 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2751 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2753 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2754 next = GST_STATE_TRANSITION_NEXT (transition);
2756 /* if the element already is in the given state, we just return success */
2757 if (next == GST_STATE_VOID_PENDING || state == next)
2760 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2761 "default handler tries setting state from %s to %s (%04x)",
2762 gst_element_state_get_name (state),
2763 gst_element_state_get_name (next), transition);
2765 switch (transition) {
2766 case GST_STATE_CHANGE_NULL_TO_READY:
2768 case GST_STATE_CHANGE_READY_TO_PAUSED:
2769 if (!gst_element_pads_activate (element, TRUE)) {
2770 result = GST_STATE_CHANGE_FAILURE;
2773 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2775 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2777 case GST_STATE_CHANGE_PAUSED_TO_READY:
2778 case GST_STATE_CHANGE_READY_TO_NULL:
2779 /* deactivate pads in both cases, since they are activated on
2780 ready->paused but the element might not have made it to paused */
2781 if (!gst_element_pads_activate (element, FALSE)) {
2782 result = GST_STATE_CHANGE_FAILURE;
2786 /* this will catch real but unhandled state changes;
2787 * can only be caused by:
2788 * - a new state was added
2789 * - somehow the element was asked to jump across an intermediate state
2791 g_warning ("Unhandled state change from %s to %s",
2792 gst_element_state_get_name (state),
2793 gst_element_state_get_name (next));
2800 GST_OBJECT_LOCK (element);
2801 result = GST_STATE_RETURN (element);
2802 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2803 "element is already in the %s state",
2804 gst_element_state_get_name (state));
2805 GST_OBJECT_UNLOCK (element);
2812 * gst_element_get_factory:
2813 * @element: a #GstElement to request the element factory of.
2815 * Retrieves the factory that was used to create this element.
2817 * Returns: (transfer none): the #GstElementFactory used for creating this
2818 * element. no refcounting is needed.
2821 gst_element_get_factory (GstElement * element)
2823 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2825 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2829 gst_element_dispose (GObject * object)
2831 GstElement *element = GST_ELEMENT_CAST (object);
2834 GstElementClass *oclass;
2837 oclass = GST_ELEMENT_GET_CLASS (element);
2839 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2841 if (GST_STATE (element) != GST_STATE_NULL)
2844 /* start by releasing all request pads, this might also remove some dynamic
2846 walk = element->pads;
2848 GstPad *pad = GST_PAD_CAST (walk->data);
2852 if (oclass->release_pad && GST_PAD_PAD_TEMPLATE (pad) &&
2853 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
2854 == GST_PAD_REQUEST) {
2855 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2856 "removing request pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2857 oclass->release_pad (element, pad);
2859 /* in case the release_pad function removed the next pad too */
2860 if (walk && g_list_position (element->pads, walk) == -1)
2861 walk = element->pads;
2864 /* remove the remaining pads */
2865 while (element->pads) {
2866 GstPad *pad = GST_PAD_CAST (element->pads->data);
2867 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2868 "removing pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2869 if (!gst_element_remove_pad (element, pad)) {
2870 /* only happens when someone unparented our pad.. */
2871 g_critical ("failed to remove pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2876 GST_OBJECT_LOCK (element);
2877 clock_p = &element->clock;
2878 bus_p = &element->bus;
2879 gst_object_replace ((GstObject **) clock_p, NULL);
2880 gst_object_replace ((GstObject **) bus_p, NULL);
2881 GST_OBJECT_UNLOCK (element);
2883 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2885 G_OBJECT_CLASS (parent_class)->dispose (object);
2894 is_locked = GST_ELEMENT_IS_LOCKED_STATE (element);
2896 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2898 "You need to explicitly set elements to the NULL state before\n"
2899 "dropping the final reference, to allow them to clean up.\n"
2900 "This problem may also be caused by a refcounting bug in the\n"
2901 "application or some element.\n",
2902 GST_OBJECT_NAME (element),
2903 gst_element_state_get_name (GST_STATE (element)),
2904 is_locked ? " (locked)" : "");
2910 gst_element_finalize (GObject * object)
2912 GstElement *element = GST_ELEMENT_CAST (object);
2914 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2916 g_cond_clear (&element->state_cond);
2917 g_rec_mutex_clear (&element->state_lock);
2919 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2921 G_OBJECT_CLASS (parent_class)->finalize (object);
2925 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2929 g_return_if_fail (GST_IS_ELEMENT (element));
2931 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2933 GST_OBJECT_LOCK (element);
2934 bus_p = &GST_ELEMENT_BUS (element);
2935 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
2936 GST_OBJECT_UNLOCK (element);
2940 * gst_element_set_bus:
2941 * @element: a #GstElement to set the bus of.
2942 * @bus: (transfer none): the #GstBus to set.
2944 * Sets the bus of the element. Increases the refcount on the bus.
2945 * For internal use only, unless you're testing elements.
2950 gst_element_set_bus (GstElement * element, GstBus * bus)
2952 GstElementClass *oclass;
2954 g_return_if_fail (GST_IS_ELEMENT (element));
2956 oclass = GST_ELEMENT_GET_CLASS (element);
2958 if (oclass->set_bus)
2959 oclass->set_bus (element, bus);
2963 * gst_element_get_bus:
2964 * @element: a #GstElement to get the bus of.
2966 * Returns the bus of the element. Note that only a #GstPipeline will provide a
2967 * bus for the application.
2969 * Returns: (transfer full): the element's #GstBus. unref after usage.
2974 gst_element_get_bus (GstElement * element)
2976 GstBus *result = NULL;
2978 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
2980 GST_OBJECT_LOCK (element);
2981 if ((result = GST_ELEMENT_BUS (element)))
2982 gst_object_ref (result);
2983 GST_OBJECT_UNLOCK (element);
2985 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,