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));
1286 g_return_if_fail (longname != NULL && *longname != '\0');
1287 g_return_if_fail (classification != NULL && *classification != '\0');
1288 g_return_if_fail (description != NULL && *description != '\0');
1289 g_return_if_fail (author != NULL && *author != '\0');
1291 gst_structure_id_set ((GstStructure *) klass->metadata,
1292 GST_QUARK (ELEMENT_METADATA_LONGNAME), G_TYPE_STRING, longname,
1293 GST_QUARK (ELEMENT_METADATA_KLASS), G_TYPE_STRING, classification,
1294 GST_QUARK (ELEMENT_METADATA_DESCRIPTION), G_TYPE_STRING, description,
1295 GST_QUARK (ELEMENT_METADATA_AUTHOR), G_TYPE_STRING, author, NULL);
1299 * gst_element_class_set_static_metadata:
1300 * @klass: class to set metadata for
1301 * @longname: The long English name of the element. E.g. "File Sink"
1302 * @classification: String describing the type of element, as an unordered list
1303 * separated with slashes ('/'). See draft-klass.txt of the design docs
1304 * for more details and common types. E.g: "Sink/File"
1305 * @description: Sentence describing the purpose of the element.
1306 * E.g: "Write stream to a file"
1307 * @author: Name and contact details of the author(s). Use \n to separate
1308 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1310 * Sets the detailed information for a #GstElementClass.
1311 * <note>This function is for use in _class_init functions only.</note>
1313 * Same as gst_element_class_set_metadata(), but @longname, @classification,
1314 * @description, and @author must be static strings or inlined strings, as
1315 * they will not be copied. (GStreamer plugins will be made resident once
1316 * loaded, so this function can be used even from dynamically loaded plugins.)
1319 gst_element_class_set_static_metadata (GstElementClass * klass,
1320 const gchar * longname, const gchar * classification,
1321 const gchar * description, const gchar * author)
1323 GstStructure *s = (GstStructure *) klass->metadata;
1324 GValue val = G_VALUE_INIT;
1326 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1327 g_return_if_fail (longname != NULL && *longname != '\0');
1328 g_return_if_fail (classification != NULL && *classification != '\0');
1329 g_return_if_fail (description != NULL && *description != '\0');
1330 g_return_if_fail (author != NULL && *author != '\0');
1332 g_value_init (&val, G_TYPE_STRING);
1334 g_value_set_static_string (&val, longname);
1335 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_LONGNAME), &val);
1337 g_value_set_static_string (&val, classification);
1338 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_KLASS), &val);
1340 g_value_set_static_string (&val, description);
1341 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_DESCRIPTION),
1344 g_value_set_static_string (&val, author);
1345 gst_structure_id_take_value (s, GST_QUARK (ELEMENT_METADATA_AUTHOR), &val);
1349 * gst_element_class_get_metadata:
1350 * @klass: class to get metadata for
1351 * @key: the key to get
1353 * Get metadata with @key in @klass.
1355 * Returns: the metadata for @key.
1358 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1360 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1361 g_return_val_if_fail (key != NULL, NULL);
1363 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1367 * gst_element_class_get_pad_template_list:
1368 * @element_class: a #GstElementClass to get pad templates of.
1370 * Retrieves a list of the pad templates associated with @element_class. The
1371 * list must not be modified by the calling code.
1372 * <note>If you use this function in the #GInstanceInitFunc of an object class
1373 * that has subclasses, make sure to pass the g_class parameter of the
1374 * #GInstanceInitFunc here.</note>
1376 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1380 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1382 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1384 return element_class->padtemplates;
1388 * gst_element_class_get_pad_template:
1389 * @element_class: a #GstElementClass to get the pad template of.
1390 * @name: the name of the #GstPadTemplate to get.
1392 * Retrieves a padtemplate from @element_class with the given name.
1393 * <note>If you use this function in the #GInstanceInitFunc of an object class
1394 * that has subclasses, make sure to pass the g_class parameter of the
1395 * #GInstanceInitFunc here.</note>
1397 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1398 * if none was found. No unreferencing is necessary.
1401 gst_element_class_get_pad_template (GstElementClass *
1402 element_class, const gchar * name)
1406 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1407 g_return_val_if_fail (name != NULL, NULL);
1409 padlist = element_class->padtemplates;
1412 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1414 if (strcmp (padtempl->name_template, name) == 0)
1417 padlist = g_list_next (padlist);
1423 static GstPadTemplate *
1424 gst_element_class_get_request_pad_template (GstElementClass *
1425 element_class, const gchar * name)
1427 GstPadTemplate *tmpl;
1429 tmpl = gst_element_class_get_pad_template (element_class, name);
1430 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1436 /* get a random pad on element of the given direction.
1437 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1440 gst_element_get_random_pad (GstElement * element,
1441 gboolean need_linked, GstPadDirection dir)
1443 GstPad *result = NULL;
1446 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1450 GST_OBJECT_LOCK (element);
1451 pads = element->srcpads;
1454 GST_OBJECT_LOCK (element);
1455 pads = element->sinkpads;
1458 goto wrong_direction;
1460 for (; pads; pads = g_list_next (pads)) {
1461 GstPad *pad = GST_PAD_CAST (pads->data);
1463 GST_OBJECT_LOCK (pad);
1464 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1465 GST_DEBUG_PAD_NAME (pad));
1467 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1468 /* if we require a linked pad, and it is not linked, continue the
1470 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1471 GST_DEBUG_PAD_NAME (pad));
1472 GST_OBJECT_UNLOCK (pad);
1475 /* found a pad, stop search */
1476 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1477 GST_DEBUG_PAD_NAME (pad));
1478 GST_OBJECT_UNLOCK (pad);
1484 gst_object_ref (result);
1486 GST_OBJECT_UNLOCK (element);
1490 /* ERROR handling */
1493 g_warning ("unknown pad direction %d", dir);
1499 gst_element_default_send_event (GstElement * element, GstEvent * event)
1501 gboolean result = FALSE;
1504 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1505 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1506 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1509 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1510 "pushing %s event to random %s pad %s:%s",
1511 GST_EVENT_TYPE_NAME (event),
1512 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1513 GST_DEBUG_PAD_NAME (pad));
1515 result = gst_pad_push_event (pad, event);
1516 gst_object_unref (pad);
1518 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1519 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1520 gst_event_unref (event);
1526 * gst_element_send_event:
1527 * @element: a #GstElement to send the event to.
1528 * @event: (transfer full): the #GstEvent to send to the element.
1530 * Sends an event to an element. If the element doesn't implement an
1531 * event handler, the event will be pushed on a random linked sink pad for
1532 * upstream events or a random linked source pad for downstream events.
1534 * This function takes owership of the provided event so you should
1535 * gst_event_ref() it if you want to reuse the event after this call.
1539 * Returns: %TRUE if the event was handled. Events that trigger a preroll (such
1540 * as flushing seeks and steps) will emit %GST_MESSAGE_ASYNC_DONE.
1543 gst_element_send_event (GstElement * element, GstEvent * event)
1545 GstElementClass *oclass;
1546 gboolean result = FALSE;
1548 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1549 g_return_val_if_fail (event != NULL, FALSE);
1551 oclass = GST_ELEMENT_GET_CLASS (element);
1553 GST_STATE_LOCK (element);
1554 if (oclass->send_event) {
1555 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1556 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1557 result = oclass->send_event (element, event);
1559 GST_STATE_UNLOCK (element);
1566 * @element: a #GstElement to send the event to.
1567 * @rate: The new playback rate
1568 * @format: The format of the seek values
1569 * @flags: The optional seek flags.
1570 * @start_type: The type and flags for the new start position
1571 * @start: The value of the new start position
1572 * @stop_type: The type and flags for the new stop position
1573 * @stop: The value of the new stop position
1575 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1576 * the parameters. The seek event is sent to the element using
1577 * gst_element_send_event().
1581 * Returns: %TRUE if the event was handled. Flushing seeks will trigger a
1582 * preroll, which will emit %GST_MESSAGE_ASYNC_DONE.
1585 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1586 GstSeekFlags flags, GstSeekType start_type, gint64 start,
1587 GstSeekType stop_type, gint64 stop)
1592 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1595 gst_event_new_seek (rate, format, flags, start_type, start, stop_type,
1597 result = gst_element_send_event (element, event);
1603 gst_element_default_query (GstElement * element, GstQuery * query)
1605 gboolean result = FALSE;
1608 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1610 result = gst_pad_query (pad, query);
1612 gst_object_unref (pad);
1614 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1616 GstPad *peer = gst_pad_get_peer (pad);
1619 result = gst_pad_query (peer, query);
1621 gst_object_unref (peer);
1623 gst_object_unref (pad);
1630 * gst_element_query:
1631 * @element: a #GstElement to perform the query on.
1632 * @query: (transfer none): the #GstQuery.
1634 * Performs a query on the given element.
1636 * For elements that don't implement a query handler, this function
1637 * forwards the query to a random srcpad or to the peer of a
1638 * random linked sinkpad of this element.
1640 * Please note that some queries might need a running pipeline to work.
1642 * Returns: TRUE if the query could be performed.
1647 gst_element_query (GstElement * element, GstQuery * query)
1649 GstElementClass *oclass;
1650 gboolean result = FALSE;
1652 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1653 g_return_val_if_fail (query != NULL, FALSE);
1655 oclass = GST_ELEMENT_GET_CLASS (element);
1657 if (oclass->query) {
1658 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1659 GST_ELEMENT_NAME (element));
1660 result = oclass->query (element, query);
1666 * gst_element_post_message:
1667 * @element: a #GstElement posting the message
1668 * @message: (transfer full): a #GstMessage to post
1670 * Post a message on the element's #GstBus. This function takes ownership of the
1671 * message; if you want to access the message after this call, you should add an
1672 * additional reference before calling.
1674 * Returns: %TRUE if the message was successfully posted. The function returns
1675 * %FALSE if the element did not have a bus.
1680 gst_element_post_message (GstElement * element, GstMessage * message)
1683 gboolean result = FALSE;
1685 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1686 g_return_val_if_fail (message != NULL, FALSE);
1688 GST_OBJECT_LOCK (element);
1691 if (G_UNLIKELY (bus == NULL))
1694 gst_object_ref (bus);
1695 GST_OBJECT_UNLOCK (element);
1697 /* we release the element lock when posting the message so that any
1698 * (synchronous) message handlers can operate on the element */
1699 result = gst_bus_post (bus, message);
1700 gst_object_unref (bus);
1707 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1708 "not posting message %p: no bus", message);
1709 GST_OBJECT_UNLOCK (element);
1710 gst_message_unref (message);
1716 * _gst_element_error_printf:
1717 * @format: the printf-like format to use, or %NULL
1719 * This function is only used internally by the gst_element_error() macro.
1721 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1727 _gst_element_error_printf (const gchar * format, ...)
1737 va_start (args, format);
1738 buffer = g_strdup_vprintf (format, args);
1744 * gst_element_message_full:
1745 * @element: a #GstElement to send message from
1746 * @type: the #GstMessageType
1747 * @domain: the GStreamer GError domain this message belongs to
1748 * @code: the GError code belonging to the domain
1749 * @text: (allow-none) (transfer full): an allocated text string to be used
1750 * as a replacement for the default message connected to code,
1752 * @debug: (allow-none) (transfer full): an allocated debug message to be
1753 * used as a replacement for the default debugging information,
1755 * @file: the source code file where the error was generated
1756 * @function: the source code function where the error was generated
1757 * @line: the source code line where the error was generated
1759 * Post an error, warning or info message on the bus from inside an element.
1761 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1762 * #GST_MESSAGE_INFO.
1766 void gst_element_message_full
1767 (GstElement * element, GstMessageType type,
1768 GQuark domain, gint code, gchar * text,
1769 gchar * debug, const gchar * file, const gchar * function, gint line)
1771 GError *gerror = NULL;
1775 gboolean has_debug = TRUE;
1776 GstMessage *message = NULL;
1779 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1780 g_return_if_fail (GST_IS_ELEMENT (element));
1781 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1782 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1784 /* check if we send the given text or the default error text */
1785 if ((text == NULL) || (text[0] == 0)) {
1786 /* text could have come from g_strdup_printf (""); */
1788 sent_text = gst_error_get_message (domain, code);
1792 /* construct a sent_debug with extra information from source */
1793 if ((debug == NULL) || (debug[0] == 0)) {
1794 /* debug could have come from g_strdup_printf (""); */
1798 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1800 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1801 file, line, function, name, debug);
1803 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1804 file, line, function, name);
1808 /* create gerror and post message */
1809 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1811 gerror = g_error_new_literal (domain, code, sent_text);
1814 case GST_MESSAGE_ERROR:
1816 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1818 case GST_MESSAGE_WARNING:
1819 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1822 case GST_MESSAGE_INFO:
1823 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1827 g_assert_not_reached ();
1830 gst_element_post_message (element, message);
1832 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1833 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1836 g_error_free (gerror);
1837 g_free (sent_debug);
1842 * gst_element_is_locked_state:
1843 * @element: a #GstElement.
1845 * Checks if the state of an element is locked.
1846 * If the state of an element is locked, state changes of the parent don't
1847 * affect the element.
1848 * This way you can leave currently unused elements inside bins. Just lock their
1849 * state before changing the state from #GST_STATE_NULL.
1853 * Returns: TRUE, if the element's state is locked.
1856 gst_element_is_locked_state (GstElement * element)
1860 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1862 GST_OBJECT_LOCK (element);
1863 result = GST_ELEMENT_IS_LOCKED_STATE (element);
1864 GST_OBJECT_UNLOCK (element);
1870 * gst_element_set_locked_state:
1871 * @element: a #GstElement
1872 * @locked_state: TRUE to lock the element's state
1874 * Locks the state of an element, so state changes of the parent don't affect
1875 * this element anymore.
1879 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1880 * or the elements state-locking needed no change.
1883 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1887 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1889 GST_OBJECT_LOCK (element);
1890 old = GST_ELEMENT_IS_LOCKED_STATE (element);
1892 if (G_UNLIKELY (old == locked_state))
1896 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1897 GST_ELEMENT_NAME (element));
1898 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1900 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1901 GST_ELEMENT_NAME (element));
1902 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1904 GST_OBJECT_UNLOCK (element);
1910 GST_CAT_DEBUG (GST_CAT_STATES,
1911 "elements %s was already in locked state %d",
1912 GST_ELEMENT_NAME (element), old);
1913 GST_OBJECT_UNLOCK (element);
1920 * gst_element_sync_state_with_parent:
1921 * @element: a #GstElement.
1923 * Tries to change the state of the element to the same as its parent.
1924 * If this function returns FALSE, the state of element is undefined.
1926 * Returns: TRUE, if the element's state could be synced to the parent's state.
1931 gst_element_sync_state_with_parent (GstElement * element)
1935 GstStateChangeReturn ret;
1937 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1939 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1940 GstState parent_current, parent_pending;
1942 GST_OBJECT_LOCK (parent);
1943 parent_current = GST_STATE (parent);
1944 parent_pending = GST_STATE_PENDING (parent);
1945 GST_OBJECT_UNLOCK (parent);
1947 /* set to pending if there is one, else we set it to the current state of
1949 if (parent_pending != GST_STATE_VOID_PENDING)
1950 target = parent_pending;
1952 target = parent_current;
1954 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1955 "syncing state (%s) to parent %s %s (%s, %s)",
1956 gst_element_state_get_name (GST_STATE (element)),
1957 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1958 gst_element_state_get_name (parent_current),
1959 gst_element_state_get_name (parent_pending));
1961 ret = gst_element_set_state (element, target);
1962 if (ret == GST_STATE_CHANGE_FAILURE)
1965 gst_object_unref (parent);
1969 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
1976 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1977 "syncing state failed (%s)",
1978 gst_element_state_change_return_get_name (ret));
1979 gst_object_unref (parent);
1985 static GstStateChangeReturn
1986 gst_element_get_state_func (GstElement * element,
1987 GstState * state, GstState * pending, GstClockTime timeout)
1989 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
1990 GstState old_pending;
1992 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
1993 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
1995 GST_OBJECT_LOCK (element);
1996 ret = GST_STATE_RETURN (element);
1997 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
1998 gst_element_state_change_return_get_name (ret));
2000 /* we got an error, report immediately */
2001 if (ret == GST_STATE_CHANGE_FAILURE)
2004 /* we got no_preroll, report immediately */
2005 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2008 /* no need to wait async if we are not async */
2009 if (ret != GST_STATE_CHANGE_ASYNC)
2012 old_pending = GST_STATE_PENDING (element);
2013 if (old_pending != GST_STATE_VOID_PENDING) {
2017 /* get cookie to detect state changes during waiting */
2018 cookie = element->state_cookie;
2020 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2021 "waiting for element to commit state");
2023 /* we have a pending state change, wait for it to complete */
2024 if (timeout != GST_CLOCK_TIME_NONE) {
2026 /* make timeout absolute */
2027 end_time = g_get_monotonic_time () + (timeout / 1000);
2028 signaled = GST_STATE_WAIT_UNTIL (element, end_time);
2030 GST_STATE_WAIT (element);
2035 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2036 /* timeout triggered */
2037 ret = GST_STATE_CHANGE_ASYNC;
2039 if (cookie != element->state_cookie)
2042 /* could be success or failure */
2043 if (old_pending == GST_STATE (element)) {
2044 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2045 ret = GST_STATE_CHANGE_SUCCESS;
2047 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2048 ret = GST_STATE_CHANGE_FAILURE;
2051 /* if nothing is pending anymore we can return SUCCESS */
2052 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2053 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2054 ret = GST_STATE_CHANGE_SUCCESS;
2060 *state = GST_STATE (element);
2062 *pending = GST_STATE_PENDING (element);
2064 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2065 "state current: %s, pending: %s, result: %s",
2066 gst_element_state_get_name (GST_STATE (element)),
2067 gst_element_state_get_name (GST_STATE_PENDING (element)),
2068 gst_element_state_change_return_get_name (ret));
2069 GST_OBJECT_UNLOCK (element);
2076 *state = GST_STATE_VOID_PENDING;
2078 *pending = GST_STATE_VOID_PENDING;
2080 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2082 GST_OBJECT_UNLOCK (element);
2084 return GST_STATE_CHANGE_FAILURE;
2089 * gst_element_get_state:
2090 * @element: a #GstElement to get the state of.
2091 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2093 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2094 * state. Can be %NULL.
2095 * @timeout: a #GstClockTime to specify the timeout for an async
2096 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2098 * Gets the state of the element.
2100 * For elements that performed an ASYNC state change, as reported by
2101 * gst_element_set_state(), this function will block up to the
2102 * specified timeout value for the state change to complete.
2103 * If the element completes the state change or goes into
2104 * an error, this function returns immediately with a return value of
2105 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2107 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2108 * returns the current and pending state immediately.
2110 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2111 * successfully changed its state but is not able to provide data yet.
2112 * This mostly happens for live sources that only produce data in
2113 * %GST_STATE_PLAYING. While the state change return is equivalent to
2114 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2115 * some sink elements might not be able to complete their state change because
2116 * an element is not producing data to complete the preroll. When setting the
2117 * element to playing, the preroll will complete and playback will start.
2119 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2120 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2121 * element is still performing a state change or
2122 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2126 GstStateChangeReturn
2127 gst_element_get_state (GstElement * element,
2128 GstState * state, GstState * pending, GstClockTime timeout)
2130 GstElementClass *oclass;
2131 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2133 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2135 oclass = GST_ELEMENT_GET_CLASS (element);
2137 if (oclass->get_state)
2138 result = (oclass->get_state) (element, state, pending, timeout);
2144 * gst_element_abort_state:
2145 * @element: a #GstElement to abort the state of.
2147 * Abort the state change of the element. This function is used
2148 * by elements that do asynchronous state changes and find out
2149 * something is wrong.
2151 * This function should be called with the STATE_LOCK held.
2156 gst_element_abort_state (GstElement * element)
2160 #ifndef GST_DISABLE_GST_DEBUG
2164 g_return_if_fail (GST_IS_ELEMENT (element));
2166 GST_OBJECT_LOCK (element);
2167 pending = GST_STATE_PENDING (element);
2169 if (pending == GST_STATE_VOID_PENDING ||
2170 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2171 goto nothing_aborted;
2173 #ifndef GST_DISABLE_GST_DEBUG
2174 old_state = GST_STATE (element);
2176 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2177 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2178 gst_element_state_get_name (pending));
2182 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2184 GST_STATE_BROADCAST (element);
2185 GST_OBJECT_UNLOCK (element);
2191 GST_OBJECT_UNLOCK (element);
2196 /* Not static because GstBin has manual state handling too */
2198 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2199 GstState newstate, GstState pending)
2201 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2202 GstMessage *message;
2204 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2205 "notifying about state-changed %s to %s (%s pending)",
2206 gst_element_state_get_name (oldstate),
2207 gst_element_state_get_name (newstate),
2208 gst_element_state_get_name (pending));
2210 if (klass->state_changed)
2211 klass->state_changed (element, oldstate, newstate, pending);
2213 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2214 oldstate, newstate, pending);
2215 gst_element_post_message (element, message);
2219 * gst_element_continue_state:
2220 * @element: a #GstElement to continue the state change of.
2221 * @ret: The previous state return value
2223 * Commit the state change of the element and proceed to the next
2224 * pending state if any. This function is used
2225 * by elements that do asynchronous state changes.
2226 * The core will normally call this method automatically when an
2227 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2229 * If after calling this method the element still has not reached
2230 * the pending state, the next state change is performed.
2232 * This method is used internally and should normally not be called by plugins
2235 * Returns: The result of the commit state change.
2239 GstStateChangeReturn
2240 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2242 GstStateChangeReturn old_ret;
2243 GstState old_state, old_next;
2244 GstState current, next, pending;
2245 GstStateChange transition;
2247 GST_OBJECT_LOCK (element);
2248 old_ret = GST_STATE_RETURN (element);
2249 GST_STATE_RETURN (element) = ret;
2250 pending = GST_STATE_PENDING (element);
2252 /* check if there is something to commit */
2253 if (pending == GST_STATE_VOID_PENDING)
2254 goto nothing_pending;
2256 old_state = GST_STATE (element);
2257 /* this is the state we should go to next */
2258 old_next = GST_STATE_NEXT (element);
2259 /* update current state */
2260 current = GST_STATE (element) = old_next;
2262 /* see if we reached the final state */
2263 if (pending == current)
2266 next = GST_STATE_GET_NEXT (current, pending);
2267 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2269 GST_STATE_NEXT (element) = next;
2271 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2272 GST_OBJECT_UNLOCK (element);
2274 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2275 "committing state from %s to %s, pending %s, next %s",
2276 gst_element_state_get_name (old_state),
2277 gst_element_state_get_name (old_next),
2278 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2280 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2282 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2283 "continue state change %s to %s, final %s",
2284 gst_element_state_get_name (current),
2285 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2287 ret = gst_element_change_state (element, transition);
2293 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2294 GST_OBJECT_UNLOCK (element);
2299 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2300 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2302 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2303 "completed state change to %s", gst_element_state_get_name (pending));
2304 GST_OBJECT_UNLOCK (element);
2306 /* don't post silly messages with the same state. This can happen
2307 * when an element state is changed to what it already was. For bins
2308 * this can be the result of a lost state, which we check with the
2309 * previous return value.
2310 * We do signal the cond though as a _get_state() might be blocking
2312 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2313 _priv_gst_element_state_changed (element, old_state, old_next,
2314 GST_STATE_VOID_PENDING);
2316 GST_STATE_BROADCAST (element);
2323 * gst_element_lost_state:
2324 * @element: a #GstElement the state is lost of
2326 * Brings the element to the lost state. The current state of the
2327 * element is copied to the pending state so that any call to
2328 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2330 * An ASYNC_START message is posted. If the element was PLAYING, it will
2331 * go to PAUSED. The element will be restored to its PLAYING state by
2332 * the parent pipeline when it prerolls again.
2334 * This is mostly used for elements that lost their preroll buffer
2335 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2336 * they will go to their pending state again when a new preroll buffer is
2337 * queued. This function can only be called when the element is currently
2338 * not in error or an async state change.
2340 * This function is used internally and should normally not be called from
2341 * plugins or applications.
2344 gst_element_lost_state (GstElement * element)
2346 GstState old_state, new_state;
2347 GstMessage *message;
2349 g_return_if_fail (GST_IS_ELEMENT (element));
2351 GST_OBJECT_LOCK (element);
2352 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2355 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2356 goto only_async_start;
2358 old_state = GST_STATE (element);
2360 /* when we were PLAYING, the new state is PAUSED. We will also not
2361 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2362 * when we preroll. */
2363 if (old_state > GST_STATE_PAUSED)
2364 new_state = GST_STATE_PAUSED;
2366 new_state = old_state;
2368 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2369 "lost state of %s to %s", gst_element_state_get_name (old_state),
2370 gst_element_state_get_name (new_state));
2372 GST_STATE (element) = new_state;
2373 GST_STATE_NEXT (element) = new_state;
2374 GST_STATE_PENDING (element) = new_state;
2375 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2376 GST_OBJECT_UNLOCK (element);
2378 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2380 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2381 gst_element_post_message (element, message);
2387 GST_OBJECT_UNLOCK (element);
2392 GST_OBJECT_UNLOCK (element);
2394 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2395 gst_element_post_message (element, message);
2401 * gst_element_set_state:
2402 * @element: a #GstElement to change state of.
2403 * @state: the element's new #GstState.
2405 * Sets the state of the element. This function will try to set the
2406 * requested state by going through all the intermediary states and calling
2407 * the class's state change function for each.
2409 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2410 * element will perform the remainder of the state change asynchronously in
2412 * An application can use gst_element_get_state() to wait for the completion
2413 * of the state change or it can wait for a state change message on the bus.
2415 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2416 * #GST_STATE_CHANGE_ASYNC.
2418 * Returns: Result of the state change using #GstStateChangeReturn.
2422 GstStateChangeReturn
2423 gst_element_set_state (GstElement * element, GstState state)
2425 GstElementClass *oclass;
2426 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2428 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2430 oclass = GST_ELEMENT_GET_CLASS (element);
2432 if (oclass->set_state)
2433 result = (oclass->set_state) (element, state);
2439 * default set state function, calculates the next state based
2440 * on current state and calls the change_state function
2442 static GstStateChangeReturn
2443 gst_element_set_state_func (GstElement * element, GstState state)
2445 GstState current, next, old_pending;
2446 GstStateChangeReturn ret;
2447 GstStateChange transition;
2448 GstStateChangeReturn old_ret;
2450 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2452 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2453 gst_element_state_get_name (state));
2455 /* state lock is taken to protect the set_state() and get_state()
2456 * procedures, it does not lock any variables. */
2457 GST_STATE_LOCK (element);
2459 /* now calculate how to get to the new state */
2460 GST_OBJECT_LOCK (element);
2461 old_ret = GST_STATE_RETURN (element);
2462 /* previous state change returned an error, remove all pending
2463 * and next states */
2464 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2465 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2466 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2467 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2470 current = GST_STATE (element);
2471 next = GST_STATE_NEXT (element);
2472 old_pending = GST_STATE_PENDING (element);
2474 /* this is the (new) state we should go to. TARGET is the last state we set on
2476 if (state != GST_STATE_TARGET (element)) {
2477 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2478 "setting target state to %s", gst_element_state_get_name (state));
2479 GST_STATE_TARGET (element) = state;
2480 /* increment state cookie so that we can track each state change. We only do
2481 * this if this is actually a new state change. */
2482 element->state_cookie++;
2484 GST_STATE_PENDING (element) = state;
2486 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2487 "current %s, old_pending %s, next %s, old return %s",
2488 gst_element_state_get_name (current),
2489 gst_element_state_get_name (old_pending),
2490 gst_element_state_get_name (next),
2491 gst_element_state_change_return_get_name (old_ret));
2493 /* if the element was busy doing a state change, we just update the
2494 * target state, it'll get to it async then. */
2495 if (old_pending != GST_STATE_VOID_PENDING) {
2496 /* upwards state change will happen ASYNC */
2497 if (old_pending <= state)
2499 /* element is going to this state already */
2500 else if (next == state)
2502 /* element was performing an ASYNC upward state change and
2503 * we request to go downward again. Start from the next pending
2505 else if (next > state
2506 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2510 next = GST_STATE_GET_NEXT (current, state);
2511 /* now we store the next state */
2512 GST_STATE_NEXT (element) = next;
2513 /* mark busy, we need to check that there is actually a state change
2514 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2515 * the default element change_state function has no way to know what the
2516 * old value was... could consider this a FIXME...*/
2517 if (current != next)
2518 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2520 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2522 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2523 "%s: setting state from %s to %s",
2524 (next != state ? "intermediate" : "final"),
2525 gst_element_state_get_name (current), gst_element_state_get_name (next));
2527 /* now signal any waiters, they will error since the cookie was incremented */
2528 GST_STATE_BROADCAST (element);
2530 GST_OBJECT_UNLOCK (element);
2532 ret = gst_element_change_state (element, transition);
2534 GST_STATE_UNLOCK (element);
2536 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2537 gst_element_state_change_return_get_name (ret));
2543 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2544 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2545 "element was busy with async state change");
2546 GST_OBJECT_UNLOCK (element);
2548 GST_STATE_UNLOCK (element);
2550 return GST_STATE_CHANGE_ASYNC;
2555 * gst_element_change_state:
2556 * @element: a #GstElement
2557 * @transition: the requested transition
2559 * Perform @transition on @element.
2561 * This function must be called with STATE_LOCK held and is mainly used
2564 * Returns: the #GstStateChangeReturn of the state transition.
2566 GstStateChangeReturn
2567 gst_element_change_state (GstElement * element, GstStateChange transition)
2569 GstElementClass *oclass;
2570 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2572 oclass = GST_ELEMENT_GET_CLASS (element);
2574 /* call the state change function so it can set the state */
2575 if (oclass->change_state)
2576 ret = (oclass->change_state) (element, transition);
2578 ret = GST_STATE_CHANGE_FAILURE;
2581 case GST_STATE_CHANGE_FAILURE:
2582 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2583 "have FAILURE change_state return");
2584 /* state change failure */
2585 gst_element_abort_state (element);
2587 case GST_STATE_CHANGE_ASYNC:
2591 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2592 "element will change state ASYNC");
2594 target = GST_STATE_TARGET (element);
2596 if (target > GST_STATE_READY)
2599 /* else we just continue the state change downwards */
2600 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2601 "forcing commit state %s <= %s",
2602 gst_element_state_get_name (target),
2603 gst_element_state_get_name (GST_STATE_READY));
2605 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2608 case GST_STATE_CHANGE_SUCCESS:
2609 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2610 "element changed state SUCCESS");
2611 /* we can commit the state now which will proceeed to
2613 ret = gst_element_continue_state (element, ret);
2615 case GST_STATE_CHANGE_NO_PREROLL:
2616 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2617 "element changed state NO_PREROLL");
2618 /* we can commit the state now which will proceeed to
2620 ret = gst_element_continue_state (element, ret);
2623 goto invalid_return;
2626 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2631 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2639 GST_OBJECT_LOCK (element);
2640 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2641 g_critical ("%s: unknown return value %d from a state change function",
2642 GST_ELEMENT_NAME (element), ret);
2644 /* we are in error now */
2645 ret = GST_STATE_CHANGE_FAILURE;
2646 GST_STATE_RETURN (element) = ret;
2647 GST_OBJECT_UNLOCK (element);
2653 /* gst_iterator_fold functions for pads_activate
2654 * Stop the iterator if activating one pad failed. */
2656 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2658 GstPad *pad = g_value_get_object (vpad);
2659 gboolean cont = TRUE;
2661 if (!(cont = gst_pad_set_active (pad, *active)))
2662 g_value_set_boolean (ret, FALSE);
2667 /* returns false on error or early cutout of the fold, true if all
2668 * pads in @iter were (de)activated successfully. */
2670 iterator_activate_fold_with_resync (GstIterator * iter,
2671 GstIteratorFoldFunction func, gpointer user_data)
2673 GstIteratorResult ires;
2676 /* no need to unset this later, it's just a boolean */
2677 g_value_init (&ret, G_TYPE_BOOLEAN);
2678 g_value_set_boolean (&ret, TRUE);
2681 ires = gst_iterator_fold (iter, func, &ret, user_data);
2683 case GST_ITERATOR_RESYNC:
2684 /* need to reset the result again */
2685 g_value_set_boolean (&ret, TRUE);
2686 gst_iterator_resync (iter);
2688 case GST_ITERATOR_DONE:
2689 /* all pads iterated, return collected value */
2692 /* iterator returned _ERROR or premature end with _OK,
2693 * mark an error and exit */
2694 g_value_set_boolean (&ret, FALSE);
2699 /* return collected value */
2700 return g_value_get_boolean (&ret);
2703 /* is called with STATE_LOCK
2705 * Pads are activated from source pads to sinkpads.
2708 gst_element_pads_activate (GstElement * element, gboolean active)
2713 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2714 "%s pads", active ? "activate" : "deactivate");
2716 iter = gst_element_iterate_src_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 iter = gst_element_iterate_sink_pads (element);
2726 iterator_activate_fold_with_resync (iter,
2727 (GstIteratorFoldFunction) activate_pads, &active);
2728 gst_iterator_free (iter);
2729 if (G_UNLIKELY (!res))
2732 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2733 "pad %sactivation successful", active ? "" : "de");
2740 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2741 "pad %sactivation failed", active ? "" : "de");
2746 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2747 "sink pads_activate failed");
2752 /* is called with STATE_LOCK */
2753 static GstStateChangeReturn
2754 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2756 GstState state, next;
2757 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2759 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2761 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2762 next = GST_STATE_TRANSITION_NEXT (transition);
2764 /* if the element already is in the given state, we just return success */
2765 if (next == GST_STATE_VOID_PENDING || state == next)
2768 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2769 "default handler tries setting state from %s to %s (%04x)",
2770 gst_element_state_get_name (state),
2771 gst_element_state_get_name (next), transition);
2773 switch (transition) {
2774 case GST_STATE_CHANGE_NULL_TO_READY:
2776 case GST_STATE_CHANGE_READY_TO_PAUSED:
2777 if (!gst_element_pads_activate (element, TRUE)) {
2778 result = GST_STATE_CHANGE_FAILURE;
2781 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2783 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2785 case GST_STATE_CHANGE_PAUSED_TO_READY:
2786 case GST_STATE_CHANGE_READY_TO_NULL:
2787 /* deactivate pads in both cases, since they are activated on
2788 ready->paused but the element might not have made it to paused */
2789 if (!gst_element_pads_activate (element, FALSE)) {
2790 result = GST_STATE_CHANGE_FAILURE;
2794 /* this will catch real but unhandled state changes;
2795 * can only be caused by:
2796 * - a new state was added
2797 * - somehow the element was asked to jump across an intermediate state
2799 g_warning ("Unhandled state change from %s to %s",
2800 gst_element_state_get_name (state),
2801 gst_element_state_get_name (next));
2808 GST_OBJECT_LOCK (element);
2809 result = GST_STATE_RETURN (element);
2810 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2811 "element is already in the %s state",
2812 gst_element_state_get_name (state));
2813 GST_OBJECT_UNLOCK (element);
2820 * gst_element_get_factory:
2821 * @element: a #GstElement to request the element factory of.
2823 * Retrieves the factory that was used to create this element.
2825 * Returns: (transfer none): the #GstElementFactory used for creating this
2826 * element. no refcounting is needed.
2829 gst_element_get_factory (GstElement * element)
2831 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2833 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2837 gst_element_dispose (GObject * object)
2839 GstElement *element = GST_ELEMENT_CAST (object);
2842 GstElementClass *oclass;
2845 oclass = GST_ELEMENT_GET_CLASS (element);
2847 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2849 if (GST_STATE (element) != GST_STATE_NULL)
2852 /* start by releasing all request pads, this might also remove some dynamic
2854 walk = element->pads;
2856 GstPad *pad = GST_PAD_CAST (walk->data);
2860 if (oclass->release_pad && GST_PAD_PAD_TEMPLATE (pad) &&
2861 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
2862 == GST_PAD_REQUEST) {
2863 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2864 "removing request pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2865 oclass->release_pad (element, pad);
2867 /* in case the release_pad function removed the next pad too */
2868 if (walk && g_list_position (element->pads, walk) == -1)
2869 walk = element->pads;
2872 /* remove the remaining pads */
2873 while (element->pads) {
2874 GstPad *pad = GST_PAD_CAST (element->pads->data);
2875 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2876 "removing pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2877 if (!gst_element_remove_pad (element, pad)) {
2878 /* only happens when someone unparented our pad.. */
2879 g_critical ("failed to remove pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2884 GST_OBJECT_LOCK (element);
2885 clock_p = &element->clock;
2886 bus_p = &element->bus;
2887 gst_object_replace ((GstObject **) clock_p, NULL);
2888 gst_object_replace ((GstObject **) bus_p, NULL);
2889 GST_OBJECT_UNLOCK (element);
2891 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2893 G_OBJECT_CLASS (parent_class)->dispose (object);
2902 is_locked = GST_ELEMENT_IS_LOCKED_STATE (element);
2904 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2906 "You need to explicitly set elements to the NULL state before\n"
2907 "dropping the final reference, to allow them to clean up.\n"
2908 "This problem may also be caused by a refcounting bug in the\n"
2909 "application or some element.\n",
2910 GST_OBJECT_NAME (element),
2911 gst_element_state_get_name (GST_STATE (element)),
2912 is_locked ? " (locked)" : "");
2918 gst_element_finalize (GObject * object)
2920 GstElement *element = GST_ELEMENT_CAST (object);
2922 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2924 g_cond_clear (&element->state_cond);
2925 g_rec_mutex_clear (&element->state_lock);
2927 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2929 G_OBJECT_CLASS (parent_class)->finalize (object);
2933 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2937 g_return_if_fail (GST_IS_ELEMENT (element));
2939 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2941 GST_OBJECT_LOCK (element);
2942 bus_p = &GST_ELEMENT_BUS (element);
2943 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
2944 GST_OBJECT_UNLOCK (element);
2948 * gst_element_set_bus:
2949 * @element: a #GstElement to set the bus of.
2950 * @bus: (transfer none): the #GstBus to set.
2952 * Sets the bus of the element. Increases the refcount on the bus.
2953 * For internal use only, unless you're testing elements.
2958 gst_element_set_bus (GstElement * element, GstBus * bus)
2960 GstElementClass *oclass;
2962 g_return_if_fail (GST_IS_ELEMENT (element));
2964 oclass = GST_ELEMENT_GET_CLASS (element);
2966 if (oclass->set_bus)
2967 oclass->set_bus (element, bus);
2971 * gst_element_get_bus:
2972 * @element: a #GstElement to get the bus of.
2974 * Returns the bus of the element. Note that only a #GstPipeline will provide a
2975 * bus for the application.
2977 * Returns: (transfer full): the element's #GstBus. unref after usage.
2982 gst_element_get_bus (GstElement * element)
2984 GstBus *result = NULL;
2986 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
2988 GST_OBJECT_LOCK (element);
2989 if ((result = GST_ELEMENT_BUS (element)))
2990 gst_object_ref (result);
2991 GST_OBJECT_UNLOCK (element);
2993 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,