2 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
3 * 2004 Wim Taymans <wim@fluendo.com>
5 * gstelement.c: The base element, all elements derive from this
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Library General Public
9 * License as published by the Free Software Foundation; either
10 * version 2 of the License, or (at your option) any later version.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Library General Public License for more details.
17 * You should have received a copy of the GNU Library General Public
18 * License along with this library; if not, write to the
19 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
20 * Boston, MA 02110-1301, USA.
25 * @short_description: Abstract base class for all pipeline elements
26 * @see_also: #GstElementFactory, #GstPad
28 * GstElement is the abstract base class needed to construct an element that
29 * can be used in a GStreamer pipeline. Please refer to the plugin writers
30 * guide for more information on creating #GstElement subclasses.
32 * The name of a #GstElement can be get with gst_element_get_name() and set with
33 * gst_element_set_name(). For speed, GST_ELEMENT_NAME() can be used in the
34 * core when using the appropriate locking. Do not use this in plug-ins or
35 * applications in order to retain ABI compatibility.
37 * Elements can have pads (of the type #GstPad). These pads link to pads on
38 * other elements. #GstBuffer flow between these linked pads.
39 * A #GstElement has a #GList of #GstPad structures for all their input (or sink)
40 * and output (or source) pads.
41 * Core and plug-in writers can add and remove pads with gst_element_add_pad()
42 * and gst_element_remove_pad().
44 * An existing pad of an element can be retrieved by name with
45 * gst_element_get_static_pad(). A new dynamic pad can be created using
46 * gst_element_request_pad() with a #GstPadTemplate 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);
133 static gboolean gst_element_post_message_default (GstElement * element,
134 GstMessage * message);
135 static void gst_element_set_context_func (GstElement * element,
136 GstContext * context);
138 static gboolean gst_element_default_send_event (GstElement * element,
140 static gboolean gst_element_default_query (GstElement * element,
143 static GstPadTemplate
144 * gst_element_class_get_request_pad_template (GstElementClass *
145 element_class, const gchar * name);
147 static GstObjectClass *parent_class = NULL;
148 static guint gst_element_signals[LAST_SIGNAL] = { 0 };
150 /* this is used in gstelementfactory.c:gst_element_register() */
151 GQuark __gst_elementclass_factory = 0;
154 gst_element_get_type (void)
156 static volatile gsize gst_element_type = 0;
158 if (g_once_init_enter (&gst_element_type)) {
160 static const GTypeInfo element_info = {
161 sizeof (GstElementClass),
162 gst_element_base_class_init,
163 gst_element_base_class_finalize,
164 (GClassInitFunc) gst_element_class_init,
169 (GInstanceInitFunc) gst_element_init,
173 _type = g_type_register_static (GST_TYPE_OBJECT, "GstElement",
174 &element_info, G_TYPE_FLAG_ABSTRACT);
176 __gst_elementclass_factory =
177 g_quark_from_static_string ("GST_ELEMENTCLASS_FACTORY");
178 g_once_init_leave (&gst_element_type, _type);
180 return gst_element_type;
184 gst_element_class_init (GstElementClass * klass)
186 GObjectClass *gobject_class;
188 gobject_class = (GObjectClass *) klass;
190 parent_class = g_type_class_peek_parent (klass);
193 * GstElement::pad-added:
194 * @gstelement: the object which received the signal
195 * @new_pad: the pad that has been added
197 * a new #GstPad has been added to the element. Note that this signal will
198 * usually be emitted from the context of the streaming thread. Also keep in
199 * mind that if you add new elements to the pipeline in the signal handler
200 * you will need to set them to the desired target state with
201 * gst_element_set_state() or gst_element_sync_state_with_parent().
203 gst_element_signals[PAD_ADDED] =
204 g_signal_new ("pad-added", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
205 G_STRUCT_OFFSET (GstElementClass, pad_added), NULL, NULL,
206 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
208 * GstElement::pad-removed:
209 * @gstelement: the object which received the signal
210 * @old_pad: the pad that has been removed
212 * a #GstPad has been removed from the element
214 gst_element_signals[PAD_REMOVED] =
215 g_signal_new ("pad-removed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
216 G_STRUCT_OFFSET (GstElementClass, pad_removed), NULL, NULL,
217 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
219 * GstElement::no-more-pads:
220 * @gstelement: the object which received the signal
222 * This signals that the element will not generate more dynamic pads.
223 * Note that this signal will usually be emitted from the context of
224 * the streaming thread.
226 gst_element_signals[NO_MORE_PADS] =
227 g_signal_new ("no-more-pads", G_TYPE_FROM_CLASS (klass),
228 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstElementClass, no_more_pads), NULL,
229 NULL, g_cclosure_marshal_generic, G_TYPE_NONE, 0);
231 gobject_class->dispose = gst_element_dispose;
232 gobject_class->finalize = gst_element_finalize;
234 klass->change_state = GST_DEBUG_FUNCPTR (gst_element_change_state_func);
235 klass->set_state = GST_DEBUG_FUNCPTR (gst_element_set_state_func);
236 klass->get_state = GST_DEBUG_FUNCPTR (gst_element_get_state_func);
237 klass->set_clock = GST_DEBUG_FUNCPTR (gst_element_set_clock_func);
238 klass->set_bus = GST_DEBUG_FUNCPTR (gst_element_set_bus_func);
239 klass->query = GST_DEBUG_FUNCPTR (gst_element_default_query);
240 klass->send_event = GST_DEBUG_FUNCPTR (gst_element_default_send_event);
241 klass->numpadtemplates = 0;
242 klass->post_message = GST_DEBUG_FUNCPTR (gst_element_post_message_default);
243 klass->set_context = GST_DEBUG_FUNCPTR (gst_element_set_context_func);
245 klass->elementfactory = NULL;
249 gst_element_base_class_init (gpointer g_class)
251 GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
252 GList *node, *padtemplates;
254 /* Copy the element details here so elements can inherit the
255 * details from their base class and classes only need to set
256 * the details in class_init instead of base_init */
257 element_class->metadata =
258 element_class->metadata ? gst_structure_copy (element_class->metadata) :
259 gst_structure_new_empty ("metadata");
261 /* Copy the pad templates so elements inherit them
262 * from their base class but elements can add pad templates in class_init
263 * instead of base_init.
265 padtemplates = g_list_copy (element_class->padtemplates);
266 for (node = padtemplates; node != NULL; node = node->next) {
267 GstPadTemplate *tmpl = (GstPadTemplate *) node->data;
268 gst_object_ref (tmpl);
270 element_class->padtemplates = padtemplates;
272 /* set the factory, see gst_element_register() */
273 element_class->elementfactory =
274 g_type_get_qdata (G_TYPE_FROM_CLASS (element_class),
275 __gst_elementclass_factory);
276 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "type %s : factory %p",
277 G_OBJECT_CLASS_NAME (element_class), element_class->elementfactory);
281 gst_element_base_class_finalize (gpointer g_class)
283 GstElementClass *klass = GST_ELEMENT_CLASS (g_class);
285 g_list_foreach (klass->padtemplates, (GFunc) gst_object_unref, NULL);
286 g_list_free (klass->padtemplates);
288 gst_structure_free (klass->metadata);
292 gst_element_init (GstElement * element)
294 GST_STATE (element) = GST_STATE_NULL;
295 GST_STATE_TARGET (element) = GST_STATE_NULL;
296 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
297 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
298 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
300 g_rec_mutex_init (&element->state_lock);
301 g_cond_init (&element->state_cond);
305 * gst_element_release_request_pad:
306 * @element: a #GstElement to release the request pad of.
307 * @pad: the #GstPad to release.
309 * Makes the element free the previously requested pad as obtained
310 * with gst_element_get_request_pad().
312 * This does not unref the pad. If the pad was created by using
313 * gst_element_get_request_pad(), gst_element_release_request_pad() needs to be
314 * followed by gst_object_unref() to free the @pad.
319 gst_element_release_request_pad (GstElement * element, GstPad * pad)
321 GstElementClass *oclass;
323 g_return_if_fail (GST_IS_ELEMENT (element));
324 g_return_if_fail (GST_IS_PAD (pad));
325 g_return_if_fail (GST_PAD_PAD_TEMPLATE (pad) == NULL ||
326 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad)) ==
329 oclass = GST_ELEMENT_GET_CLASS (element);
331 /* if the element implements a custom release function we call that, else we
332 * simply remove the pad from the element */
333 if (oclass->release_pad)
334 oclass->release_pad (element, pad);
336 gst_element_remove_pad (element, pad);
340 * gst_element_provide_clock:
341 * @element: a #GstElement to query
343 * Get the clock provided by the given element.
344 * <note>An element is only required to provide a clock in the PAUSED
345 * state. Some elements can provide a clock in other states.</note>
347 * Returns: (transfer full): the GstClock provided by the element or %NULL
348 * if no clock could be provided. Unref after usage.
353 gst_element_provide_clock (GstElement * element)
355 GstClock *result = NULL;
356 GstElementClass *oclass;
358 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
360 oclass = GST_ELEMENT_GET_CLASS (element);
362 if (oclass->provide_clock)
363 result = oclass->provide_clock (element);
369 gst_element_set_clock_func (GstElement * element, GstClock * clock)
373 GST_OBJECT_LOCK (element);
374 clock_p = &element->clock;
375 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
376 GST_OBJECT_UNLOCK (element);
382 * gst_element_set_clock:
383 * @element: a #GstElement to set the clock for.
384 * @clock: the #GstClock to set for the element.
386 * Sets the clock for the element. This function increases the
387 * refcount on the clock. Any previously set clock on the object
390 * Returns: %TRUE if the element accepted the clock. An element can refuse a
391 * clock when it, for example, is not able to slave its internal clock to the
392 * @clock or when it requires a specific clock to operate.
397 gst_element_set_clock (GstElement * element, GstClock * clock)
399 GstElementClass *oclass;
400 gboolean res = FALSE;
402 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
403 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
405 oclass = GST_ELEMENT_GET_CLASS (element);
407 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
409 if (oclass->set_clock)
410 res = oclass->set_clock (element, clock);
416 * gst_element_get_clock:
417 * @element: a #GstElement to get the clock of.
419 * Gets the currently configured clock of the element. This is the clock as was
420 * last set with gst_element_set_clock().
422 * Returns: (transfer full): the #GstClock of the element. unref after usage.
427 gst_element_get_clock (GstElement * element)
431 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
433 GST_OBJECT_LOCK (element);
434 if ((result = element->clock))
435 gst_object_ref (result);
436 GST_OBJECT_UNLOCK (element);
442 * gst_element_set_base_time:
443 * @element: a #GstElement.
444 * @time: the base time to set.
446 * Set the base time of an element. See gst_element_get_base_time().
451 gst_element_set_base_time (GstElement * element, GstClockTime time)
455 g_return_if_fail (GST_IS_ELEMENT (element));
457 GST_OBJECT_LOCK (element);
458 old = element->base_time;
459 element->base_time = time;
460 GST_OBJECT_UNLOCK (element);
462 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
463 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
464 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
468 * gst_element_get_base_time:
469 * @element: a #GstElement.
471 * Returns the base time of the element. The base time is the
472 * absolute time of the clock when this element was last put to
473 * PLAYING. Subtracting the base time from the clock time gives
474 * the running time of the element.
476 * Returns: the base time of the element.
481 gst_element_get_base_time (GstElement * element)
485 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
487 GST_OBJECT_LOCK (element);
488 result = element->base_time;
489 GST_OBJECT_UNLOCK (element);
495 * gst_element_set_start_time:
496 * @element: a #GstElement.
497 * @time: the base time to set.
499 * Set the start time of an element. The start time of the element is the
500 * running time of the element when it last went to the PAUSED state. In READY
501 * or after a flushing seek, it is set to 0.
503 * Toplevel elements like #GstPipeline will manage the start_time and
504 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
505 * on such a toplevel element will disable the distribution of the base_time to
506 * the children and can be useful if the application manages the base_time
507 * itself, for example if you want to synchronize capture from multiple
508 * pipelines, and you can also ensure that the pipelines have the same clock.
513 gst_element_set_start_time (GstElement * element, GstClockTime time)
517 g_return_if_fail (GST_IS_ELEMENT (element));
519 GST_OBJECT_LOCK (element);
520 old = GST_ELEMENT_START_TIME (element);
521 GST_ELEMENT_START_TIME (element) = time;
522 GST_OBJECT_UNLOCK (element);
524 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
525 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
526 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
530 * gst_element_get_start_time:
531 * @element: a #GstElement.
533 * Returns the start time of the element. The start time is the
534 * running time of the clock when this element was last put to PAUSED.
536 * Usually the start_time is managed by a toplevel element such as
541 * Returns: the start time of the element.
544 gst_element_get_start_time (GstElement * element)
548 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
550 GST_OBJECT_LOCK (element);
551 result = GST_ELEMENT_START_TIME (element);
552 GST_OBJECT_UNLOCK (element);
559 * gst_element_set_index:
560 * @element: a #GstElement.
561 * @index: (transfer none): a #GstIndex.
563 * Set @index on the element. The refcount of the index
564 * will be increased, any previously set index is unreffed.
569 gst_element_set_index (GstElement * element, GstIndex * index)
571 GstElementClass *oclass;
573 g_return_if_fail (GST_IS_ELEMENT (element));
574 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
576 oclass = GST_ELEMENT_GET_CLASS (element);
578 if (oclass->set_index)
579 oclass->set_index (element, index);
583 * gst_element_get_index:
584 * @element: a #GstElement.
586 * Gets the index from the element.
588 * Returns: (transfer full): a #GstIndex or %NULL when no index was set on the
589 * element. unref after usage.
594 gst_element_get_index (GstElement * element)
596 GstElementClass *oclass;
597 GstIndex *result = NULL;
599 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
601 oclass = GST_ELEMENT_GET_CLASS (element);
603 if (oclass->get_index)
604 result = oclass->get_index (element);
611 * gst_element_add_pad:
612 * @element: a #GstElement to add the pad to.
613 * @pad: (transfer full): the #GstPad to add to the element.
615 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
616 * see gst_object_set_parent() for refcounting information.
618 * Pads are not automatically activated so elements should perform the needed
619 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
620 * state. See gst_pad_set_active() for more information about activating pads.
622 * The pad and the element should be unlocked when calling this function.
624 * This function will emit the #GstElement::pad-added signal on the element.
626 * Returns: %TRUE if the pad could be added. This function can fail when
627 * a pad with the same name already existed or the pad already had another
633 gst_element_add_pad (GstElement * element, GstPad * pad)
638 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
639 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
641 /* locking pad to look at the name */
642 GST_OBJECT_LOCK (pad);
643 pad_name = g_strdup (GST_PAD_NAME (pad));
644 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
645 GST_STR_NULL (pad_name));
646 flushing = GST_PAD_IS_FLUSHING (pad);
647 GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_NEED_PARENT);
648 GST_OBJECT_UNLOCK (pad);
650 /* then check to see if there's already a pad by that name here */
651 GST_OBJECT_LOCK (element);
652 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
655 /* try to set the pad's parent */
656 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
657 GST_OBJECT_CAST (element))))
660 /* check for flushing pads */
661 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
662 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
663 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
664 "use gst_pad_set_active(pad,TRUE) before adding it.",
665 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
667 GST_OBJECT_LOCK (pad);
668 GST_PAD_UNSET_FLUSHING (pad);
669 GST_OBJECT_UNLOCK (pad);
674 /* add it to the list */
675 switch (gst_pad_get_direction (pad)) {
677 element->srcpads = g_list_append (element->srcpads, pad);
678 element->numsrcpads++;
681 element->sinkpads = g_list_append (element->sinkpads, pad);
682 element->numsinkpads++;
687 element->pads = g_list_append (element->pads, pad);
689 element->pads_cookie++;
690 GST_OBJECT_UNLOCK (element);
692 /* emit the PAD_ADDED signal */
693 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
700 g_critical ("Padname %s is not unique in element %s, not adding",
701 pad_name, GST_ELEMENT_NAME (element));
702 GST_OBJECT_UNLOCK (element);
709 ("Pad %s already has parent when trying to add to element %s",
710 pad_name, GST_ELEMENT_NAME (element));
711 GST_OBJECT_UNLOCK (element);
717 GST_OBJECT_LOCK (pad);
719 ("Trying to add pad %s to element %s, but it has no direction",
720 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
721 GST_OBJECT_UNLOCK (pad);
722 GST_OBJECT_UNLOCK (element);
728 * gst_element_remove_pad:
729 * @element: a #GstElement to remove pad from.
730 * @pad: (transfer full): the #GstPad to remove from the element.
732 * Removes @pad from @element. @pad will be destroyed if it has not been
733 * referenced elsewhere using gst_object_unparent().
735 * This function is used by plugin developers and should not be used
736 * by applications. Pads that were dynamically requested from elements
737 * with gst_element_get_request_pad() should be released with the
738 * gst_element_release_request_pad() function instead.
740 * Pads are not automatically deactivated so elements should perform the needed
741 * steps to deactivate the pad in case this pad is removed in the PAUSED or
742 * PLAYING state. See gst_pad_set_active() for more information about
745 * The pad and the element should be unlocked when calling this function.
747 * This function will emit the #GstElement::pad-removed signal on the element.
749 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
750 * pad does not belong to the provided element.
755 gst_element_remove_pad (GstElement * element, GstPad * pad)
759 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
760 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
762 /* locking pad to look at the name and parent */
763 GST_OBJECT_LOCK (pad);
764 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
765 GST_STR_NULL (GST_PAD_NAME (pad)));
767 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
769 GST_OBJECT_UNLOCK (pad);
772 if ((peer = gst_pad_get_peer (pad))) {
773 /* window for MT unsafeness, someone else could unlink here
774 * and then we call unlink with wrong pads. The unlink
775 * function would catch this and safely return failed. */
776 if (GST_PAD_IS_SRC (pad))
777 gst_pad_unlink (pad, peer);
779 gst_pad_unlink (peer, pad);
781 gst_object_unref (peer);
784 GST_OBJECT_LOCK (element);
785 /* remove it from the list */
786 switch (gst_pad_get_direction (pad)) {
788 element->srcpads = g_list_remove (element->srcpads, pad);
789 element->numsrcpads--;
792 element->sinkpads = g_list_remove (element->sinkpads, pad);
793 element->numsinkpads--;
796 g_critical ("Removing pad without direction???");
799 element->pads = g_list_remove (element->pads, pad);
801 element->pads_cookie++;
802 GST_OBJECT_UNLOCK (element);
804 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
805 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
807 gst_object_unparent (GST_OBJECT_CAST (pad));
814 /* locking order is element > pad */
815 GST_OBJECT_UNLOCK (pad);
817 GST_OBJECT_LOCK (element);
818 GST_OBJECT_LOCK (pad);
819 g_critical ("Padname %s:%s does not belong to element %s when removing",
820 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
821 GST_OBJECT_UNLOCK (pad);
822 GST_OBJECT_UNLOCK (element);
828 * gst_element_no_more_pads:
829 * @element: a #GstElement
831 * Use this function to signal that the element does not expect any more pads
832 * to show up in the current pipeline. This function should be called whenever
833 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
834 * pad templates use this in combination with autopluggers to figure out that
835 * the element is done initializing its pads.
837 * This function emits the #GstElement::no-more-pads signal.
842 gst_element_no_more_pads (GstElement * element)
844 g_return_if_fail (GST_IS_ELEMENT (element));
846 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
850 pad_compare_name (GstPad * pad1, const gchar * name)
854 GST_OBJECT_LOCK (pad1);
855 result = strcmp (GST_PAD_NAME (pad1), name);
856 GST_OBJECT_UNLOCK (pad1);
862 * gst_element_get_static_pad:
863 * @element: a #GstElement to find a static pad of.
864 * @name: the name of the static #GstPad to retrieve.
866 * Retrieves a pad from @element by name. This version only retrieves
867 * already-existing (i.e. 'static') pads.
869 * Returns: (transfer full): the requested #GstPad if found, otherwise %NULL.
875 gst_element_get_static_pad (GstElement * element, const gchar * name)
878 GstPad *result = NULL;
880 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
881 g_return_val_if_fail (name != NULL, NULL);
883 GST_OBJECT_LOCK (element);
885 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
887 result = GST_PAD_CAST (find->data);
888 gst_object_ref (result);
891 if (result == NULL) {
892 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
893 name, GST_ELEMENT_NAME (element));
895 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
896 GST_ELEMENT_NAME (element), name);
898 GST_OBJECT_UNLOCK (element);
904 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
905 const gchar * name, const GstCaps * caps)
907 GstPad *newpad = NULL;
908 GstElementClass *oclass;
910 oclass = GST_ELEMENT_GET_CLASS (element);
912 #ifndef G_DISABLE_CHECKS
913 /* Some sanity checking here */
917 /* Is this the template name? */
918 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
919 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
921 const gchar *str, *data;
924 /* Otherwise check if it's a valid name for the name template */
925 str = strchr (templ->name_template, '%');
926 g_return_val_if_fail (str != NULL, NULL);
927 g_return_val_if_fail (strncmp (templ->name_template, name,
928 str - templ->name_template) == 0, NULL);
929 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
931 data = name + (str - templ->name_template);
933 /* Can either be %s or %d or %u, do sanity checking for %d */
934 if (*(str + 1) == 'd') {
938 tmp = g_ascii_strtoll (data, &endptr, 10);
939 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
940 && *endptr == '\0', NULL);
941 } else if (*(str + 1) == 'u') {
945 tmp = g_ascii_strtoull (data, &endptr, 10);
946 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
950 pad = gst_element_get_static_pad (element, name);
952 gst_object_unref (pad);
953 /* FIXME 0.11: Change this to g_return_val_if_fail() */
954 g_critical ("Element %s already has a pad named %s, the behaviour of "
955 " gst_element_get_request_pad() for existing pads is undefined!",
956 GST_ELEMENT_NAME (element), name);
961 if (oclass->request_new_pad)
962 newpad = (oclass->request_new_pad) (element, templ, name, caps);
965 gst_object_ref (newpad);
971 * gst_element_get_request_pad:
972 * @element: a #GstElement to find a request pad of.
973 * @name: the name of the request #GstPad to retrieve.
975 * Retrieves a pad from the element by name (e.g. "src_\%d"). This version only
976 * retrieves request pads. The pad should be released with
977 * gst_element_release_request_pad().
979 * This method is slow and will be deprecated in the future. New code should
980 * use gst_element_request_pad() with the requested template.
982 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
983 * Release after usage.
986 gst_element_get_request_pad (GstElement * element, const gchar * name)
988 GstPadTemplate *templ = NULL;
990 const gchar *req_name = NULL;
991 gboolean templ_found = FALSE;
994 gchar *str, *endptr = NULL;
995 GstElementClass *class;
997 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
998 g_return_val_if_fail (name != NULL, NULL);
1000 class = GST_ELEMENT_GET_CLASS (element);
1002 /* if the name contains a %, we assume it's the complete template name. Get
1003 * the template and try to get a pad */
1004 if (strstr (name, "%")) {
1005 templ = gst_element_class_get_request_pad_template (class, name);
1010 /* there is no % in the name, try to find a matching template */
1011 list = class->padtemplates;
1012 while (!templ_found && list) {
1013 templ = (GstPadTemplate *) list->data;
1014 if (templ->presence == GST_PAD_REQUEST) {
1015 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1016 templ->name_template);
1017 /* see if we find an exact match */
1018 if (strcmp (name, templ->name_template) == 0) {
1023 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1024 and %d and %u, occurring at the end of the name_template, are the only
1026 else if ((str = strchr (templ->name_template, '%'))
1027 && strncmp (templ->name_template, name,
1028 str - templ->name_template) == 0
1029 && strlen (name) > str - templ->name_template) {
1030 data = name + (str - templ->name_template);
1031 if (*(str + 1) == 'd') {
1035 tmp = strtol (data, &endptr, 10);
1036 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1042 } else if (*(str + 1) == 'u') {
1046 tmp = strtoul (data, &endptr, 10);
1047 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1067 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1073 * gst_element_request_pad:
1074 * @element: a #GstElement to find a request pad of.
1075 * @templ: a #GstPadTemplate of which we want a pad of.
1076 * @name: (transfer none) (allow-none): the name of the request #GstPad
1077 * to retrieve. Can be %NULL.
1078 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1079 * request. Can be %NULL.
1081 * Retrieves a request pad from the element according to the provided template.
1082 * Pad templates can be looked up using
1083 * gst_element_factory_get_static_pad_templates().
1085 * The pad should be released with gst_element_release_request_pad().
1087 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1088 * Release after usage.
1091 gst_element_request_pad (GstElement * element,
1092 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1094 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1095 g_return_val_if_fail (templ != NULL, NULL);
1096 g_return_val_if_fail (templ->presence == GST_PAD_REQUEST, NULL);
1098 return _gst_element_request_pad (element, templ, name, caps);
1101 static GstIterator *
1102 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1104 GstIterator *result;
1106 GST_OBJECT_LOCK (element);
1107 result = gst_iterator_new_list (GST_TYPE_PAD,
1108 GST_OBJECT_GET_LOCK (element),
1109 &element->pads_cookie, padlist, (GObject *) element, NULL);
1110 GST_OBJECT_UNLOCK (element);
1116 * gst_element_iterate_pads:
1117 * @element: a #GstElement to iterate pads of.
1119 * Retrieves an iterator of @element's pads. The iterator should
1120 * be freed after usage. Also more specialized iterators exists such as
1121 * gst_element_iterate_src_pads() or gst_element_iterate_sink_pads().
1123 * The order of pads returned by the iterator will be the order in which
1124 * the pads were added to the element.
1126 * Returns: (transfer full): the #GstIterator of #GstPad.
1131 gst_element_iterate_pads (GstElement * element)
1133 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1135 return gst_element_iterate_pad_list (element, &element->pads);
1139 * gst_element_iterate_src_pads:
1140 * @element: a #GstElement.
1142 * Retrieves an iterator of @element's source pads.
1144 * The order of pads returned by the iterator will be the order in which
1145 * the pads were added to the element.
1147 * Returns: (transfer full): the #GstIterator of #GstPad.
1152 gst_element_iterate_src_pads (GstElement * element)
1154 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1156 return gst_element_iterate_pad_list (element, &element->srcpads);
1160 * gst_element_iterate_sink_pads:
1161 * @element: a #GstElement.
1163 * Retrieves an iterator of @element's sink pads.
1165 * The order of pads returned by the iterator will be the order in which
1166 * the pads were added to the element.
1168 * Returns: (transfer full): the #GstIterator of #GstPad.
1173 gst_element_iterate_sink_pads (GstElement * element)
1175 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1177 return gst_element_iterate_pad_list (element, &element->sinkpads);
1181 * gst_element_class_add_pad_template:
1182 * @klass: the #GstElementClass to add the pad template to.
1183 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1185 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1186 * functions of classes. If a pad template with the same name as an already
1187 * existing one is added the old one is replaced by the new one.
1191 gst_element_class_add_pad_template (GstElementClass * klass,
1192 GstPadTemplate * templ)
1194 GList *template_list = klass->padtemplates;
1196 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1197 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1199 /* If we already have a pad template with the same name replace the
1201 while (template_list) {
1202 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1204 /* Found pad with the same name, replace and return */
1205 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1206 gst_object_unref (padtempl);
1207 template_list->data = templ;
1210 template_list = g_list_next (template_list);
1213 /* Take ownership of the floating ref */
1214 gst_object_ref_sink (templ);
1216 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1217 klass->numpadtemplates++;
1221 * gst_element_class_add_metadata:
1222 * @klass: class to set metadata for
1223 * @key: the key to set
1224 * @value: the value to set
1226 * Set @key with @value as metadata in @klass.
1229 gst_element_class_add_metadata (GstElementClass * klass,
1230 const gchar * key, const gchar * value)
1232 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1233 g_return_if_fail (key != NULL);
1234 g_return_if_fail (value != NULL);
1236 gst_structure_set ((GstStructure *) klass->metadata,
1237 key, G_TYPE_STRING, value, NULL);
1241 * gst_element_class_add_static_metadata:
1242 * @klass: class to set metadata for
1243 * @key: the key to set
1244 * @value: the value to set
1246 * Set @key with @value as metadata in @klass.
1248 * Same as gst_element_class_add_metadata(), but @value must be a static string
1249 * or an inlined string, as it will not be copied. (GStreamer plugins will
1250 * be made resident once loaded, so this function can be used even from
1251 * dynamically loaded plugins.)
1254 gst_element_class_add_static_metadata (GstElementClass * klass,
1255 const gchar * key, const gchar * value)
1257 GValue val = G_VALUE_INIT;
1259 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1260 g_return_if_fail (key != NULL);
1261 g_return_if_fail (value != NULL);
1263 g_value_init (&val, G_TYPE_STRING);
1264 g_value_set_static_string (&val, value);
1265 gst_structure_take_value ((GstStructure *) klass->metadata, key, &val);
1269 * gst_element_class_set_metadata:
1270 * @klass: class to set metadata for
1271 * @longname: The long English name of the element. E.g. "File Sink"
1272 * @classification: String describing the type of element, as an unordered list
1273 * separated with slashes ('/'). See draft-klass.txt of the design docs
1274 * for more details and common types. E.g: "Sink/File"
1275 * @description: Sentence describing the purpose of the element.
1276 * E.g: "Write stream to a file"
1277 * @author: Name and contact details of the author(s). Use \n to separate
1278 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1280 * Sets the detailed information for a #GstElementClass.
1281 * <note>This function is for use in _class_init functions only.</note>
1284 gst_element_class_set_metadata (GstElementClass * klass,
1285 const gchar * longname, const gchar * classification,
1286 const gchar * description, const gchar * author)
1288 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1289 g_return_if_fail (longname != NULL && *longname != '\0');
1290 g_return_if_fail (classification != NULL && *classification != '\0');
1291 g_return_if_fail (description != NULL && *description != '\0');
1292 g_return_if_fail (author != NULL && *author != '\0');
1294 gst_structure_id_set ((GstStructure *) klass->metadata,
1295 GST_QUARK (ELEMENT_METADATA_LONGNAME), G_TYPE_STRING, longname,
1296 GST_QUARK (ELEMENT_METADATA_KLASS), G_TYPE_STRING, classification,
1297 GST_QUARK (ELEMENT_METADATA_DESCRIPTION), G_TYPE_STRING, description,
1298 GST_QUARK (ELEMENT_METADATA_AUTHOR), G_TYPE_STRING, author, NULL);
1302 * gst_element_class_set_static_metadata:
1303 * @klass: class to set metadata for
1304 * @longname: The long English name of the element. E.g. "File Sink"
1305 * @classification: String describing the type of element, as an unordered list
1306 * separated with slashes ('/'). See draft-klass.txt of the design docs
1307 * for more details and common types. E.g: "Sink/File"
1308 * @description: Sentence describing the purpose of the element.
1309 * E.g: "Write stream to a file"
1310 * @author: Name and contact details of the author(s). Use \n to separate
1311 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1313 * Sets the detailed information for a #GstElementClass.
1314 * <note>This function is for use in _class_init functions only.</note>
1316 * Same as gst_element_class_set_metadata(), but @longname, @classification,
1317 * @description, and @author must be static strings or inlined strings, as
1318 * they will not be copied. (GStreamer plugins will be made resident once
1319 * loaded, so this function can be used even from dynamically loaded plugins.)
1322 gst_element_class_set_static_metadata (GstElementClass * klass,
1323 const gchar * longname, const gchar * classification,
1324 const gchar * description, const gchar * author)
1326 GstStructure *s = (GstStructure *) klass->metadata;
1327 GValue val = G_VALUE_INIT;
1329 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1330 g_return_if_fail (longname != NULL && *longname != '\0');
1331 g_return_if_fail (classification != NULL && *classification != '\0');
1332 g_return_if_fail (description != NULL && *description != '\0');
1333 g_return_if_fail (author != NULL && *author != '\0');
1335 g_value_init (&val, G_TYPE_STRING);
1337 g_value_set_static_string (&val, longname);
1338 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_LONGNAME), &val);
1340 g_value_set_static_string (&val, classification);
1341 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_KLASS), &val);
1343 g_value_set_static_string (&val, description);
1344 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_DESCRIPTION),
1347 g_value_set_static_string (&val, author);
1348 gst_structure_id_take_value (s, GST_QUARK (ELEMENT_METADATA_AUTHOR), &val);
1352 * gst_element_class_get_metadata:
1353 * @klass: class to get metadata for
1354 * @key: the key to get
1356 * Get metadata with @key in @klass.
1358 * Returns: the metadata for @key.
1361 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1363 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1364 g_return_val_if_fail (key != NULL, NULL);
1366 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1370 * gst_element_class_get_pad_template_list:
1371 * @element_class: a #GstElementClass to get pad templates of.
1373 * Retrieves a list of the pad templates associated with @element_class. The
1374 * list must not be modified by the calling code.
1375 * <note>If you use this function in the #GInstanceInitFunc of an object class
1376 * that has subclasses, make sure to pass the g_class parameter of the
1377 * #GInstanceInitFunc here.</note>
1379 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1383 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1385 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1387 return element_class->padtemplates;
1391 * gst_element_class_get_pad_template:
1392 * @element_class: a #GstElementClass to get the pad template of.
1393 * @name: the name of the #GstPadTemplate to get.
1395 * Retrieves a padtemplate from @element_class with the given name.
1396 * <note>If you use this function in the #GInstanceInitFunc of an object class
1397 * that has subclasses, make sure to pass the g_class parameter of the
1398 * #GInstanceInitFunc here.</note>
1400 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1401 * if none was found. No unreferencing is necessary.
1404 gst_element_class_get_pad_template (GstElementClass *
1405 element_class, const gchar * name)
1409 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1410 g_return_val_if_fail (name != NULL, NULL);
1412 padlist = element_class->padtemplates;
1415 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1417 if (strcmp (padtempl->name_template, name) == 0)
1420 padlist = g_list_next (padlist);
1426 static GstPadTemplate *
1427 gst_element_class_get_request_pad_template (GstElementClass *
1428 element_class, const gchar * name)
1430 GstPadTemplate *tmpl;
1432 tmpl = gst_element_class_get_pad_template (element_class, name);
1433 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1439 /* get a random pad on element of the given direction.
1440 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1443 gst_element_get_random_pad (GstElement * element,
1444 gboolean need_linked, GstPadDirection dir)
1446 GstPad *result = NULL;
1449 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1453 GST_OBJECT_LOCK (element);
1454 pads = element->srcpads;
1457 GST_OBJECT_LOCK (element);
1458 pads = element->sinkpads;
1461 goto wrong_direction;
1463 for (; pads; pads = g_list_next (pads)) {
1464 GstPad *pad = GST_PAD_CAST (pads->data);
1466 GST_OBJECT_LOCK (pad);
1467 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1468 GST_DEBUG_PAD_NAME (pad));
1470 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1471 /* if we require a linked pad, and it is not linked, continue the
1473 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1474 GST_DEBUG_PAD_NAME (pad));
1475 GST_OBJECT_UNLOCK (pad);
1478 /* found a pad, stop search */
1479 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1480 GST_DEBUG_PAD_NAME (pad));
1481 GST_OBJECT_UNLOCK (pad);
1487 gst_object_ref (result);
1489 GST_OBJECT_UNLOCK (element);
1493 /* ERROR handling */
1496 g_warning ("unknown pad direction %d", dir);
1502 gst_element_default_send_event (GstElement * element, GstEvent * event)
1504 gboolean result = FALSE;
1507 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1508 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1509 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1512 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1513 "pushing %s event to random %s pad %s:%s",
1514 GST_EVENT_TYPE_NAME (event),
1515 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1516 GST_DEBUG_PAD_NAME (pad));
1518 result = gst_pad_push_event (pad, event);
1519 gst_object_unref (pad);
1521 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1522 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1523 gst_event_unref (event);
1529 * gst_element_send_event:
1530 * @element: a #GstElement to send the event to.
1531 * @event: (transfer full): the #GstEvent to send to the element.
1533 * Sends an event to an element. If the element doesn't implement an
1534 * event handler, the event will be pushed on a random linked sink pad for
1535 * upstream events or a random linked source pad for downstream events.
1537 * This function takes owership of the provided event so you should
1538 * gst_event_ref() it if you want to reuse the event after this call.
1542 * Returns: %TRUE if the event was handled. Events that trigger a preroll (such
1543 * as flushing seeks and steps) will emit %GST_MESSAGE_ASYNC_DONE.
1546 gst_element_send_event (GstElement * element, GstEvent * event)
1548 GstElementClass *oclass;
1549 gboolean result = FALSE;
1551 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1552 g_return_val_if_fail (event != NULL, FALSE);
1554 oclass = GST_ELEMENT_GET_CLASS (element);
1556 GST_STATE_LOCK (element);
1557 if (oclass->send_event) {
1558 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1559 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1560 result = oclass->send_event (element, event);
1562 GST_STATE_UNLOCK (element);
1569 * @element: a #GstElement to send the event to.
1570 * @rate: The new playback rate
1571 * @format: The format of the seek values
1572 * @flags: The optional seek flags.
1573 * @start_type: The type and flags for the new start position
1574 * @start: The value of the new start position
1575 * @stop_type: The type and flags for the new stop position
1576 * @stop: The value of the new stop position
1578 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1579 * the parameters. The seek event is sent to the element using
1580 * gst_element_send_event().
1584 * Returns: %TRUE if the event was handled. Flushing seeks will trigger a
1585 * preroll, which will emit %GST_MESSAGE_ASYNC_DONE.
1588 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1589 GstSeekFlags flags, GstSeekType start_type, gint64 start,
1590 GstSeekType stop_type, gint64 stop)
1595 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1598 gst_event_new_seek (rate, format, flags, start_type, start, stop_type,
1600 result = gst_element_send_event (element, event);
1606 gst_element_default_query (GstElement * element, GstQuery * query)
1608 gboolean result = FALSE;
1611 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1613 result = gst_pad_query (pad, query);
1615 gst_object_unref (pad);
1617 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1619 GstPad *peer = gst_pad_get_peer (pad);
1622 result = gst_pad_query (peer, query);
1624 gst_object_unref (peer);
1626 gst_object_unref (pad);
1633 * gst_element_query:
1634 * @element: a #GstElement to perform the query on.
1635 * @query: (transfer none): the #GstQuery.
1637 * Performs a query on the given element.
1639 * For elements that don't implement a query handler, this function
1640 * forwards the query to a random srcpad or to the peer of a
1641 * random linked sinkpad of this element.
1643 * Please note that some queries might need a running pipeline to work.
1645 * Returns: TRUE if the query could be performed.
1650 gst_element_query (GstElement * element, GstQuery * query)
1652 GstElementClass *oclass;
1653 gboolean result = FALSE;
1655 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1656 g_return_val_if_fail (query != NULL, FALSE);
1658 oclass = GST_ELEMENT_GET_CLASS (element);
1660 if (oclass->query) {
1661 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1662 GST_ELEMENT_NAME (element));
1663 result = oclass->query (element, query);
1669 gst_element_post_message_default (GstElement * element, GstMessage * message)
1672 gboolean result = FALSE;
1674 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1675 g_return_val_if_fail (message != NULL, FALSE);
1677 GST_OBJECT_LOCK (element);
1680 if (G_UNLIKELY (bus == NULL))
1683 gst_object_ref (bus);
1684 GST_OBJECT_UNLOCK (element);
1686 /* we release the element lock when posting the message so that any
1687 * (synchronous) message handlers can operate on the element */
1688 result = gst_bus_post (bus, message);
1689 gst_object_unref (bus);
1696 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1697 "not posting message %p: no bus", message);
1698 GST_OBJECT_UNLOCK (element);
1699 gst_message_unref (message);
1705 * gst_element_post_message:
1706 * @element: a #GstElement posting the message
1707 * @message: (transfer full): a #GstMessage to post
1709 * Post a message on the element's #GstBus. This function takes ownership of the
1710 * message; if you want to access the message after this call, you should add an
1711 * additional reference before calling.
1713 * Returns: %TRUE if the message was successfully posted. The function returns
1714 * %FALSE if the element did not have a bus.
1719 gst_element_post_message (GstElement * element, GstMessage * message)
1721 GstElementClass *klass;
1723 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1725 klass = GST_ELEMENT_GET_CLASS (element);
1726 if (klass->post_message)
1727 return klass->post_message (element, message);
1733 * _gst_element_error_printf:
1734 * @format: the printf-like format to use, or %NULL
1736 * This function is only used internally by the gst_element_error() macro.
1738 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1744 _gst_element_error_printf (const gchar * format, ...)
1754 va_start (args, format);
1755 buffer = g_strdup_vprintf (format, args);
1761 * gst_element_message_full:
1762 * @element: a #GstElement to send message from
1763 * @type: the #GstMessageType
1764 * @domain: the GStreamer GError domain this message belongs to
1765 * @code: the GError code belonging to the domain
1766 * @text: (allow-none) (transfer full): an allocated text string to be used
1767 * as a replacement for the default message connected to code,
1769 * @debug: (allow-none) (transfer full): an allocated debug message to be
1770 * used as a replacement for the default debugging information,
1772 * @file: the source code file where the error was generated
1773 * @function: the source code function where the error was generated
1774 * @line: the source code line where the error was generated
1776 * Post an error, warning or info message on the bus from inside an element.
1778 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1779 * #GST_MESSAGE_INFO.
1783 void gst_element_message_full
1784 (GstElement * element, GstMessageType type,
1785 GQuark domain, gint code, gchar * text,
1786 gchar * debug, const gchar * file, const gchar * function, gint line)
1788 GError *gerror = NULL;
1792 gboolean has_debug = TRUE;
1793 GstMessage *message = NULL;
1796 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1797 g_return_if_fail (GST_IS_ELEMENT (element));
1798 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1799 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1801 /* check if we send the given text or the default error text */
1802 if ((text == NULL) || (text[0] == 0)) {
1803 /* text could have come from g_strdup_printf (""); */
1805 sent_text = gst_error_get_message (domain, code);
1809 /* construct a sent_debug with extra information from source */
1810 if ((debug == NULL) || (debug[0] == 0)) {
1811 /* debug could have come from g_strdup_printf (""); */
1815 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1817 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1818 file, line, function, name, debug);
1820 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1821 file, line, function, name);
1825 /* create gerror and post message */
1826 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1828 gerror = g_error_new_literal (domain, code, sent_text);
1831 case GST_MESSAGE_ERROR:
1833 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1835 case GST_MESSAGE_WARNING:
1836 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1839 case GST_MESSAGE_INFO:
1840 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1844 g_assert_not_reached ();
1847 gst_element_post_message (element, message);
1849 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1850 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1853 g_error_free (gerror);
1854 g_free (sent_debug);
1859 * gst_element_is_locked_state:
1860 * @element: a #GstElement.
1862 * Checks if the state of an element is locked.
1863 * If the state of an element is locked, state changes of the parent don't
1864 * affect the element.
1865 * This way you can leave currently unused elements inside bins. Just lock their
1866 * state before changing the state from #GST_STATE_NULL.
1870 * Returns: TRUE, if the element's state is locked.
1873 gst_element_is_locked_state (GstElement * element)
1877 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1879 GST_OBJECT_LOCK (element);
1880 result = GST_ELEMENT_IS_LOCKED_STATE (element);
1881 GST_OBJECT_UNLOCK (element);
1887 * gst_element_set_locked_state:
1888 * @element: a #GstElement
1889 * @locked_state: TRUE to lock the element's state
1891 * Locks the state of an element, so state changes of the parent don't affect
1892 * this element anymore.
1896 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1897 * or the elements state-locking needed no change.
1900 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1904 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1906 GST_OBJECT_LOCK (element);
1907 old = GST_ELEMENT_IS_LOCKED_STATE (element);
1909 if (G_UNLIKELY (old == locked_state))
1913 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1914 GST_ELEMENT_NAME (element));
1915 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1917 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1918 GST_ELEMENT_NAME (element));
1919 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1921 GST_OBJECT_UNLOCK (element);
1927 GST_CAT_DEBUG (GST_CAT_STATES,
1928 "elements %s was already in locked state %d",
1929 GST_ELEMENT_NAME (element), old);
1930 GST_OBJECT_UNLOCK (element);
1937 * gst_element_sync_state_with_parent:
1938 * @element: a #GstElement.
1940 * Tries to change the state of the element to the same as its parent.
1941 * If this function returns FALSE, the state of element is undefined.
1943 * Returns: TRUE, if the element's state could be synced to the parent's state.
1948 gst_element_sync_state_with_parent (GstElement * element)
1952 GstStateChangeReturn ret;
1954 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1956 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1957 GstState parent_current, parent_pending;
1959 GST_OBJECT_LOCK (parent);
1960 parent_current = GST_STATE (parent);
1961 parent_pending = GST_STATE_PENDING (parent);
1962 GST_OBJECT_UNLOCK (parent);
1964 /* set to pending if there is one, else we set it to the current state of
1966 if (parent_pending != GST_STATE_VOID_PENDING)
1967 target = parent_pending;
1969 target = parent_current;
1971 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1972 "syncing state (%s) to parent %s %s (%s, %s)",
1973 gst_element_state_get_name (GST_STATE (element)),
1974 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1975 gst_element_state_get_name (parent_current),
1976 gst_element_state_get_name (parent_pending));
1978 ret = gst_element_set_state (element, target);
1979 if (ret == GST_STATE_CHANGE_FAILURE)
1982 gst_object_unref (parent);
1986 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
1993 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1994 "syncing state failed (%s)",
1995 gst_element_state_change_return_get_name (ret));
1996 gst_object_unref (parent);
2002 static GstStateChangeReturn
2003 gst_element_get_state_func (GstElement * element,
2004 GstState * state, GstState * pending, GstClockTime timeout)
2006 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2007 GstState old_pending;
2009 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2010 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2012 GST_OBJECT_LOCK (element);
2013 ret = GST_STATE_RETURN (element);
2014 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2015 gst_element_state_change_return_get_name (ret));
2017 /* we got an error, report immediately */
2018 if (ret == GST_STATE_CHANGE_FAILURE)
2021 /* we got no_preroll, report immediately */
2022 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2025 /* no need to wait async if we are not async */
2026 if (ret != GST_STATE_CHANGE_ASYNC)
2029 old_pending = GST_STATE_PENDING (element);
2030 if (old_pending != GST_STATE_VOID_PENDING) {
2034 /* get cookie to detect state changes during waiting */
2035 cookie = element->state_cookie;
2037 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2038 "waiting for element to commit state");
2040 /* we have a pending state change, wait for it to complete */
2041 if (timeout != GST_CLOCK_TIME_NONE) {
2043 /* make timeout absolute */
2044 end_time = g_get_monotonic_time () + (timeout / 1000);
2045 signaled = GST_STATE_WAIT_UNTIL (element, end_time);
2047 GST_STATE_WAIT (element);
2052 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2053 /* timeout triggered */
2054 ret = GST_STATE_CHANGE_ASYNC;
2056 if (cookie != element->state_cookie)
2059 /* could be success or failure */
2060 if (old_pending == GST_STATE (element)) {
2061 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2062 ret = GST_STATE_CHANGE_SUCCESS;
2064 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2065 ret = GST_STATE_CHANGE_FAILURE;
2068 /* if nothing is pending anymore we can return SUCCESS */
2069 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2070 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2071 ret = GST_STATE_CHANGE_SUCCESS;
2077 *state = GST_STATE (element);
2079 *pending = GST_STATE_PENDING (element);
2081 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2082 "state current: %s, pending: %s, result: %s",
2083 gst_element_state_get_name (GST_STATE (element)),
2084 gst_element_state_get_name (GST_STATE_PENDING (element)),
2085 gst_element_state_change_return_get_name (ret));
2086 GST_OBJECT_UNLOCK (element);
2093 *state = GST_STATE_VOID_PENDING;
2095 *pending = GST_STATE_VOID_PENDING;
2097 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2099 GST_OBJECT_UNLOCK (element);
2101 return GST_STATE_CHANGE_FAILURE;
2106 * gst_element_get_state:
2107 * @element: a #GstElement to get the state of.
2108 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2110 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2111 * state. Can be %NULL.
2112 * @timeout: a #GstClockTime to specify the timeout for an async
2113 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2115 * Gets the state of the element.
2117 * For elements that performed an ASYNC state change, as reported by
2118 * gst_element_set_state(), this function will block up to the
2119 * specified timeout value for the state change to complete.
2120 * If the element completes the state change or goes into
2121 * an error, this function returns immediately with a return value of
2122 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2124 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2125 * returns the current and pending state immediately.
2127 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2128 * successfully changed its state but is not able to provide data yet.
2129 * This mostly happens for live sources that only produce data in
2130 * %GST_STATE_PLAYING. While the state change return is equivalent to
2131 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2132 * some sink elements might not be able to complete their state change because
2133 * an element is not producing data to complete the preroll. When setting the
2134 * element to playing, the preroll will complete and playback will start.
2136 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2137 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2138 * element is still performing a state change or
2139 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2143 GstStateChangeReturn
2144 gst_element_get_state (GstElement * element,
2145 GstState * state, GstState * pending, GstClockTime timeout)
2147 GstElementClass *oclass;
2148 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2150 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2152 oclass = GST_ELEMENT_GET_CLASS (element);
2154 if (oclass->get_state)
2155 result = (oclass->get_state) (element, state, pending, timeout);
2161 * gst_element_abort_state:
2162 * @element: a #GstElement to abort the state of.
2164 * Abort the state change of the element. This function is used
2165 * by elements that do asynchronous state changes and find out
2166 * something is wrong.
2168 * This function should be called with the STATE_LOCK held.
2173 gst_element_abort_state (GstElement * element)
2177 #ifndef GST_DISABLE_GST_DEBUG
2181 g_return_if_fail (GST_IS_ELEMENT (element));
2183 GST_OBJECT_LOCK (element);
2184 pending = GST_STATE_PENDING (element);
2186 if (pending == GST_STATE_VOID_PENDING ||
2187 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2188 goto nothing_aborted;
2190 #ifndef GST_DISABLE_GST_DEBUG
2191 old_state = GST_STATE (element);
2193 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2194 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2195 gst_element_state_get_name (pending));
2199 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2201 GST_STATE_BROADCAST (element);
2202 GST_OBJECT_UNLOCK (element);
2208 GST_OBJECT_UNLOCK (element);
2213 /* Not static because GstBin has manual state handling too */
2215 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2216 GstState newstate, GstState pending)
2218 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2219 GstMessage *message;
2221 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2222 "notifying about state-changed %s to %s (%s pending)",
2223 gst_element_state_get_name (oldstate),
2224 gst_element_state_get_name (newstate),
2225 gst_element_state_get_name (pending));
2227 if (klass->state_changed)
2228 klass->state_changed (element, oldstate, newstate, pending);
2230 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2231 oldstate, newstate, pending);
2232 gst_element_post_message (element, message);
2236 * gst_element_continue_state:
2237 * @element: a #GstElement to continue the state change of.
2238 * @ret: The previous state return value
2240 * Commit the state change of the element and proceed to the next
2241 * pending state if any. This function is used
2242 * by elements that do asynchronous state changes.
2243 * The core will normally call this method automatically when an
2244 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2246 * If after calling this method the element still has not reached
2247 * the pending state, the next state change is performed.
2249 * This method is used internally and should normally not be called by plugins
2252 * Returns: The result of the commit state change.
2256 GstStateChangeReturn
2257 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2259 GstStateChangeReturn old_ret;
2260 GstState old_state, old_next;
2261 GstState current, next, pending;
2262 GstStateChange transition;
2264 GST_OBJECT_LOCK (element);
2265 old_ret = GST_STATE_RETURN (element);
2266 GST_STATE_RETURN (element) = ret;
2267 pending = GST_STATE_PENDING (element);
2269 /* check if there is something to commit */
2270 if (pending == GST_STATE_VOID_PENDING)
2271 goto nothing_pending;
2273 old_state = GST_STATE (element);
2274 /* this is the state we should go to next */
2275 old_next = GST_STATE_NEXT (element);
2276 /* update current state */
2277 current = GST_STATE (element) = old_next;
2279 /* see if we reached the final state */
2280 if (pending == current)
2283 next = GST_STATE_GET_NEXT (current, pending);
2284 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2286 GST_STATE_NEXT (element) = next;
2288 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2289 GST_OBJECT_UNLOCK (element);
2291 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2292 "committing state from %s to %s, pending %s, next %s",
2293 gst_element_state_get_name (old_state),
2294 gst_element_state_get_name (old_next),
2295 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2297 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2299 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2300 "continue state change %s to %s, final %s",
2301 gst_element_state_get_name (current),
2302 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2304 ret = gst_element_change_state (element, transition);
2310 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2311 GST_OBJECT_UNLOCK (element);
2316 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2317 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2319 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2320 "completed state change to %s", gst_element_state_get_name (pending));
2321 GST_OBJECT_UNLOCK (element);
2323 /* don't post silly messages with the same state. This can happen
2324 * when an element state is changed to what it already was. For bins
2325 * this can be the result of a lost state, which we check with the
2326 * previous return value.
2327 * We do signal the cond though as a _get_state() might be blocking
2329 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2330 _priv_gst_element_state_changed (element, old_state, old_next,
2331 GST_STATE_VOID_PENDING);
2333 GST_STATE_BROADCAST (element);
2340 * gst_element_lost_state:
2341 * @element: a #GstElement the state is lost of
2343 * Brings the element to the lost state. The current state of the
2344 * element is copied to the pending state so that any call to
2345 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2347 * An ASYNC_START message is posted. If the element was PLAYING, it will
2348 * go to PAUSED. The element will be restored to its PLAYING state by
2349 * the parent pipeline when it prerolls again.
2351 * This is mostly used for elements that lost their preroll buffer
2352 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2353 * they will go to their pending state again when a new preroll buffer is
2354 * queued. This function can only be called when the element is currently
2355 * not in error or an async state change.
2357 * This function is used internally and should normally not be called from
2358 * plugins or applications.
2361 gst_element_lost_state (GstElement * element)
2363 GstState old_state, new_state;
2364 GstMessage *message;
2366 g_return_if_fail (GST_IS_ELEMENT (element));
2368 GST_OBJECT_LOCK (element);
2369 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2372 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2373 goto only_async_start;
2375 old_state = GST_STATE (element);
2377 /* when we were PLAYING, the new state is PAUSED. We will also not
2378 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2379 * when we preroll. */
2380 if (old_state > GST_STATE_PAUSED)
2381 new_state = GST_STATE_PAUSED;
2383 new_state = old_state;
2385 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2386 "lost state of %s to %s", gst_element_state_get_name (old_state),
2387 gst_element_state_get_name (new_state));
2389 GST_STATE (element) = new_state;
2390 GST_STATE_NEXT (element) = new_state;
2391 GST_STATE_PENDING (element) = new_state;
2392 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2393 GST_OBJECT_UNLOCK (element);
2395 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2397 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2398 gst_element_post_message (element, message);
2404 GST_OBJECT_UNLOCK (element);
2409 GST_OBJECT_UNLOCK (element);
2411 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2412 gst_element_post_message (element, message);
2418 * gst_element_set_state:
2419 * @element: a #GstElement to change state of.
2420 * @state: the element's new #GstState.
2422 * Sets the state of the element. This function will try to set the
2423 * requested state by going through all the intermediary states and calling
2424 * the class's state change function for each.
2426 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2427 * element will perform the remainder of the state change asynchronously in
2429 * An application can use gst_element_get_state() to wait for the completion
2430 * of the state change or it can wait for a %GST_MESSAGE_ASYNC_DONE or
2431 * %GST_MESSAGE_STATE_CHANGED on the bus.
2433 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2434 * #GST_STATE_CHANGE_ASYNC.
2436 * Returns: Result of the state change using #GstStateChangeReturn.
2440 GstStateChangeReturn
2441 gst_element_set_state (GstElement * element, GstState state)
2443 GstElementClass *oclass;
2444 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2446 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2448 oclass = GST_ELEMENT_GET_CLASS (element);
2450 if (oclass->set_state)
2451 result = (oclass->set_state) (element, state);
2457 * default set state function, calculates the next state based
2458 * on current state and calls the change_state function
2460 static GstStateChangeReturn
2461 gst_element_set_state_func (GstElement * element, GstState state)
2463 GstState current, next, old_pending;
2464 GstStateChangeReturn ret;
2465 GstStateChange transition;
2466 GstStateChangeReturn old_ret;
2468 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2470 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2471 gst_element_state_get_name (state));
2473 /* state lock is taken to protect the set_state() and get_state()
2474 * procedures, it does not lock any variables. */
2475 GST_STATE_LOCK (element);
2477 /* now calculate how to get to the new state */
2478 GST_OBJECT_LOCK (element);
2479 old_ret = GST_STATE_RETURN (element);
2480 /* previous state change returned an error, remove all pending
2481 * and next states */
2482 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2483 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2484 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2485 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2488 current = GST_STATE (element);
2489 next = GST_STATE_NEXT (element);
2490 old_pending = GST_STATE_PENDING (element);
2492 /* this is the (new) state we should go to. TARGET is the last state we set on
2494 if (state != GST_STATE_TARGET (element)) {
2495 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2496 "setting target state to %s", gst_element_state_get_name (state));
2497 GST_STATE_TARGET (element) = state;
2498 /* increment state cookie so that we can track each state change. We only do
2499 * this if this is actually a new state change. */
2500 element->state_cookie++;
2502 GST_STATE_PENDING (element) = state;
2504 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2505 "current %s, old_pending %s, next %s, old return %s",
2506 gst_element_state_get_name (current),
2507 gst_element_state_get_name (old_pending),
2508 gst_element_state_get_name (next),
2509 gst_element_state_change_return_get_name (old_ret));
2511 /* if the element was busy doing a state change, we just update the
2512 * target state, it'll get to it async then. */
2513 if (old_pending != GST_STATE_VOID_PENDING) {
2514 /* upwards state change will happen ASYNC */
2515 if (old_pending <= state)
2517 /* element is going to this state already */
2518 else if (next == state)
2520 /* element was performing an ASYNC upward state change and
2521 * we request to go downward again. Start from the next pending
2523 else if (next > state
2524 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2528 next = GST_STATE_GET_NEXT (current, state);
2529 /* now we store the next state */
2530 GST_STATE_NEXT (element) = next;
2531 /* mark busy, we need to check that there is actually a state change
2532 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2533 * the default element change_state function has no way to know what the
2534 * old value was... could consider this a FIXME...*/
2535 if (current != next)
2536 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2538 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2540 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2541 "%s: setting state from %s to %s",
2542 (next != state ? "intermediate" : "final"),
2543 gst_element_state_get_name (current), gst_element_state_get_name (next));
2545 /* now signal any waiters, they will error since the cookie was incremented */
2546 GST_STATE_BROADCAST (element);
2548 GST_OBJECT_UNLOCK (element);
2550 ret = gst_element_change_state (element, transition);
2552 GST_STATE_UNLOCK (element);
2554 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2555 gst_element_state_change_return_get_name (ret));
2561 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2562 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2563 "element was busy with async state change");
2564 GST_OBJECT_UNLOCK (element);
2566 GST_STATE_UNLOCK (element);
2568 return GST_STATE_CHANGE_ASYNC;
2573 * gst_element_change_state:
2574 * @element: a #GstElement
2575 * @transition: the requested transition
2577 * Perform @transition on @element.
2579 * This function must be called with STATE_LOCK held and is mainly used
2582 * Returns: the #GstStateChangeReturn of the state transition.
2584 GstStateChangeReturn
2585 gst_element_change_state (GstElement * element, GstStateChange transition)
2587 GstElementClass *oclass;
2588 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2590 oclass = GST_ELEMENT_GET_CLASS (element);
2592 /* call the state change function so it can set the state */
2593 if (oclass->change_state)
2594 ret = (oclass->change_state) (element, transition);
2596 ret = GST_STATE_CHANGE_FAILURE;
2599 case GST_STATE_CHANGE_FAILURE:
2600 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2601 "have FAILURE change_state return");
2602 /* state change failure */
2603 gst_element_abort_state (element);
2605 case GST_STATE_CHANGE_ASYNC:
2609 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2610 "element will change state ASYNC");
2612 target = GST_STATE_TARGET (element);
2614 if (target > GST_STATE_READY)
2617 /* else we just continue the state change downwards */
2618 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2619 "forcing commit state %s <= %s",
2620 gst_element_state_get_name (target),
2621 gst_element_state_get_name (GST_STATE_READY));
2623 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2626 case GST_STATE_CHANGE_SUCCESS:
2627 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2628 "element changed state SUCCESS");
2629 /* we can commit the state now which will proceeed to
2631 ret = gst_element_continue_state (element, ret);
2633 case GST_STATE_CHANGE_NO_PREROLL:
2634 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2635 "element changed state NO_PREROLL");
2636 /* we can commit the state now which will proceeed to
2638 ret = gst_element_continue_state (element, ret);
2641 goto invalid_return;
2644 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2649 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2657 GST_OBJECT_LOCK (element);
2658 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2659 g_critical ("%s: unknown return value %d from a state change function",
2660 GST_ELEMENT_NAME (element), ret);
2662 /* we are in error now */
2663 ret = GST_STATE_CHANGE_FAILURE;
2664 GST_STATE_RETURN (element) = ret;
2665 GST_OBJECT_UNLOCK (element);
2671 /* gst_iterator_fold functions for pads_activate
2672 * Stop the iterator if activating one pad failed. */
2674 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2676 GstPad *pad = g_value_get_object (vpad);
2677 gboolean cont = TRUE;
2679 if (!(cont = gst_pad_set_active (pad, *active)))
2680 g_value_set_boolean (ret, FALSE);
2685 /* returns false on error or early cutout of the fold, true if all
2686 * pads in @iter were (de)activated successfully. */
2688 iterator_activate_fold_with_resync (GstIterator * iter,
2689 GstIteratorFoldFunction func, gpointer user_data)
2691 GstIteratorResult ires;
2694 /* no need to unset this later, it's just a boolean */
2695 g_value_init (&ret, G_TYPE_BOOLEAN);
2696 g_value_set_boolean (&ret, TRUE);
2699 ires = gst_iterator_fold (iter, func, &ret, user_data);
2701 case GST_ITERATOR_RESYNC:
2702 /* need to reset the result again */
2703 g_value_set_boolean (&ret, TRUE);
2704 gst_iterator_resync (iter);
2706 case GST_ITERATOR_DONE:
2707 /* all pads iterated, return collected value */
2710 /* iterator returned _ERROR or premature end with _OK,
2711 * mark an error and exit */
2712 g_value_set_boolean (&ret, FALSE);
2717 /* return collected value */
2718 return g_value_get_boolean (&ret);
2721 /* is called with STATE_LOCK
2723 * Pads are activated from source pads to sinkpads.
2726 gst_element_pads_activate (GstElement * element, gboolean active)
2731 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2732 "%s pads", active ? "activate" : "deactivate");
2734 iter = gst_element_iterate_src_pads (element);
2736 iterator_activate_fold_with_resync (iter,
2737 (GstIteratorFoldFunction) activate_pads, &active);
2738 gst_iterator_free (iter);
2739 if (G_UNLIKELY (!res))
2742 iter = gst_element_iterate_sink_pads (element);
2744 iterator_activate_fold_with_resync (iter,
2745 (GstIteratorFoldFunction) activate_pads, &active);
2746 gst_iterator_free (iter);
2747 if (G_UNLIKELY (!res))
2750 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2751 "pad %sactivation successful", active ? "" : "de");
2758 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2759 "pad %sactivation failed", active ? "" : "de");
2764 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2765 "sink pads_activate failed");
2770 /* is called with STATE_LOCK */
2771 static GstStateChangeReturn
2772 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2774 GstState state, next;
2775 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2777 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2779 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2780 next = GST_STATE_TRANSITION_NEXT (transition);
2782 /* if the element already is in the given state, we just return success */
2783 if (next == GST_STATE_VOID_PENDING || state == next)
2786 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2787 "default handler tries setting state from %s to %s (%04x)",
2788 gst_element_state_get_name (state),
2789 gst_element_state_get_name (next), transition);
2791 switch (transition) {
2792 case GST_STATE_CHANGE_NULL_TO_READY:
2794 case GST_STATE_CHANGE_READY_TO_PAUSED:
2795 if (!gst_element_pads_activate (element, TRUE)) {
2796 result = GST_STATE_CHANGE_FAILURE;
2799 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2801 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2803 case GST_STATE_CHANGE_PAUSED_TO_READY:
2804 case GST_STATE_CHANGE_READY_TO_NULL:
2805 /* deactivate pads in both cases, since they are activated on
2806 ready->paused but the element might not have made it to paused */
2807 if (!gst_element_pads_activate (element, FALSE)) {
2808 result = GST_STATE_CHANGE_FAILURE;
2812 /* this will catch real but unhandled state changes;
2813 * can only be caused by:
2814 * - a new state was added
2815 * - somehow the element was asked to jump across an intermediate state
2817 g_warning ("Unhandled state change from %s to %s",
2818 gst_element_state_get_name (state),
2819 gst_element_state_get_name (next));
2826 GST_OBJECT_LOCK (element);
2827 result = GST_STATE_RETURN (element);
2828 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2829 "element is already in the %s state",
2830 gst_element_state_get_name (state));
2831 GST_OBJECT_UNLOCK (element);
2838 * gst_element_get_factory:
2839 * @element: a #GstElement to request the element factory of.
2841 * Retrieves the factory that was used to create this element.
2843 * Returns: (transfer none): the #GstElementFactory used for creating this
2844 * element. no refcounting is needed.
2847 gst_element_get_factory (GstElement * element)
2849 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2851 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2855 gst_element_dispose (GObject * object)
2857 GstElement *element = GST_ELEMENT_CAST (object);
2860 GstElementClass *oclass;
2863 oclass = GST_ELEMENT_GET_CLASS (element);
2865 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2867 if (GST_STATE (element) != GST_STATE_NULL)
2870 /* start by releasing all request pads, this might also remove some dynamic
2872 walk = element->pads;
2874 GstPad *pad = GST_PAD_CAST (walk->data);
2878 if (oclass->release_pad && GST_PAD_PAD_TEMPLATE (pad) &&
2879 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
2880 == GST_PAD_REQUEST) {
2881 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2882 "removing request pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2883 oclass->release_pad (element, pad);
2885 /* in case the release_pad function removed the next pad too */
2886 if (walk && g_list_position (element->pads, walk) == -1)
2887 walk = element->pads;
2890 /* remove the remaining pads */
2891 while (element->pads) {
2892 GstPad *pad = GST_PAD_CAST (element->pads->data);
2893 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2894 "removing pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2895 if (!gst_element_remove_pad (element, pad)) {
2896 /* only happens when someone unparented our pad.. */
2897 g_critical ("failed to remove pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2902 GST_OBJECT_LOCK (element);
2903 clock_p = &element->clock;
2904 bus_p = &element->bus;
2905 gst_object_replace ((GstObject **) clock_p, NULL);
2906 gst_object_replace ((GstObject **) bus_p, NULL);
2907 gst_context_replace (&element->context, NULL);
2908 GST_OBJECT_UNLOCK (element);
2910 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2912 G_OBJECT_CLASS (parent_class)->dispose (object);
2921 is_locked = GST_ELEMENT_IS_LOCKED_STATE (element);
2923 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2925 "You need to explicitly set elements to the NULL state before\n"
2926 "dropping the final reference, to allow them to clean up.\n"
2927 "This problem may also be caused by a refcounting bug in the\n"
2928 "application or some element.\n",
2929 GST_OBJECT_NAME (element),
2930 gst_element_state_get_name (GST_STATE (element)),
2931 is_locked ? " (locked)" : "");
2937 gst_element_finalize (GObject * object)
2939 GstElement *element = GST_ELEMENT_CAST (object);
2941 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2943 g_cond_clear (&element->state_cond);
2944 g_rec_mutex_clear (&element->state_lock);
2946 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2948 G_OBJECT_CLASS (parent_class)->finalize (object);
2952 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2956 g_return_if_fail (GST_IS_ELEMENT (element));
2958 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2960 GST_OBJECT_LOCK (element);
2961 bus_p = &GST_ELEMENT_BUS (element);
2962 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
2963 GST_OBJECT_UNLOCK (element);
2967 * gst_element_set_bus:
2968 * @element: a #GstElement to set the bus of.
2969 * @bus: (transfer none): the #GstBus to set.
2971 * Sets the bus of the element. Increases the refcount on the bus.
2972 * For internal use only, unless you're testing elements.
2977 gst_element_set_bus (GstElement * element, GstBus * bus)
2979 GstElementClass *oclass;
2981 g_return_if_fail (GST_IS_ELEMENT (element));
2983 oclass = GST_ELEMENT_GET_CLASS (element);
2985 if (oclass->set_bus)
2986 oclass->set_bus (element, bus);
2990 * gst_element_get_bus:
2991 * @element: a #GstElement to get the bus of.
2993 * Returns the bus of the element. Note that only a #GstPipeline will provide a
2994 * bus for the application.
2996 * Returns: (transfer full): the element's #GstBus. unref after usage.
3001 gst_element_get_bus (GstElement * element)
3003 GstBus *result = NULL;
3005 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3007 GST_OBJECT_LOCK (element);
3008 if ((result = GST_ELEMENT_BUS (element)))
3009 gst_object_ref (result);
3010 GST_OBJECT_UNLOCK (element);
3012 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,
3019 gst_element_set_context_func (GstElement * element, GstContext * context)
3021 GST_OBJECT_LOCK (element);
3022 gst_context_replace (&element->context, context);
3023 GST_OBJECT_UNLOCK (element);
3027 * gst_element_set_context:
3028 * @element: a #GstElement to set the context of.
3029 * @context: (transfer none): the #GstContext to set.
3031 * Sets the context of the element. Increases the refcount of the context.
3036 gst_element_set_context (GstElement * element, GstContext * context)
3038 GstElementClass *oclass;
3040 g_return_if_fail (GST_IS_ELEMENT (element));
3042 oclass = GST_ELEMENT_GET_CLASS (element);
3044 GST_CAT_DEBUG_OBJECT (GST_CAT_CONTEXT, element,
3045 "set context %p %" GST_PTR_FORMAT, context,
3046 gst_context_get_structure (context));
3048 if (oclass->set_context)
3049 oclass->set_context (element, context);
3053 * gst_element_get_context:
3054 * @element: a #GstElement to get the context from.
3056 * Gets the current context of the element.
3060 * Returns: (transfer full): The current context of the element
3063 gst_element_get_context (GstElement * element)
3065 GstContext *context = NULL;
3067 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
3069 GST_OBJECT_LOCK (element);
3070 if (element->context)
3071 context = gst_context_ref (element->context);
3072 GST_OBJECT_UNLOCK (element);