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.
47 * An iterator of all pads can be retrieved with gst_element_iterate_pads().
49 * Elements can be linked through their pads.
50 * If the link is straightforward, use the gst_element_link()
51 * convenience function to link two elements, or gst_element_link_many()
52 * for more elements in a row.
53 * Use gst_element_link_filtered() to link two elements constrained by
54 * a specified set of #GstCaps.
55 * For finer control, use gst_element_link_pads() and
56 * gst_element_link_pads_filtered() to specify the pads to link on
57 * each element by name.
59 * Each element has a state (see #GstState). You can get and set the state
60 * of an element with gst_element_get_state() and gst_element_set_state().
61 * Setting a state triggers a #GstStateChange. To get a string representation
62 * of a #GstState, use gst_element_state_get_name().
64 * You can get and set a #GstClock on an element using gst_element_get_clock()
65 * and gst_element_set_clock().
66 * Some elements can provide a clock for the pipeline if
67 * the #GST_ELEMENT_FLAG_PROVIDE_CLOCK flag is set. With the
68 * gst_element_provide_clock() method one can retrieve the clock provided by
70 * Not all elements require a clock to operate correctly. If the
71 * #GST_ELEMENT_FLAG_REQUIRE_CLOCK() flag is set, a clock should be set on the
72 * element with gst_element_set_clock().
74 * Note that clock selection and distribution is normally handled by the
75 * toplevel #GstPipeline so the clock functions are only to be used in very
76 * specific situations.
79 #include "gst_private.h"
82 #include <gobject/gvaluecollector.h>
84 #include "gstelement.h"
85 #include "gstelementmetadata.h"
86 #include "gstenumtypes.h"
93 #include "gsttracer.h"
95 #include "gst-i18n-lib.h"
96 #include "glib-compat-private.h"
98 #ifndef GST_DISABLE_GST_DEBUG
99 #include "printf/printf.h"
102 /* Element signals and args */
118 static void gst_element_class_init (GstElementClass * klass);
119 static void gst_element_init (GstElement * element);
120 static void gst_element_base_class_init (gpointer g_class);
121 static void gst_element_base_class_finalize (gpointer g_class);
123 static void gst_element_dispose (GObject * object);
124 static void gst_element_finalize (GObject * object);
126 static GstStateChangeReturn gst_element_change_state_func (GstElement * element,
127 GstStateChange transition);
128 static GstStateChangeReturn gst_element_get_state_func (GstElement * element,
129 GstState * state, GstState * pending, GstClockTime timeout);
130 static GstStateChangeReturn gst_element_set_state_func (GstElement * element,
132 static gboolean gst_element_set_clock_func (GstElement * element,
134 static void gst_element_set_bus_func (GstElement * element, GstBus * bus);
135 static gboolean gst_element_post_message_default (GstElement * element,
136 GstMessage * message);
137 static void gst_element_set_context_default (GstElement * element,
138 GstContext * context);
140 static gboolean gst_element_default_send_event (GstElement * element,
142 static gboolean gst_element_default_query (GstElement * element,
145 static GstPadTemplate
146 * gst_element_class_get_request_pad_template (GstElementClass *
147 element_class, const gchar * name);
149 static GstObjectClass *parent_class = NULL;
150 static guint gst_element_signals[LAST_SIGNAL] = { 0 };
152 /* this is used in gstelementfactory.c:gst_element_register() */
153 GQuark __gst_elementclass_factory = 0;
156 gst_element_get_type (void)
158 static volatile gsize gst_element_type = 0;
160 if (g_once_init_enter (&gst_element_type)) {
162 static const GTypeInfo element_info = {
163 sizeof (GstElementClass),
164 gst_element_base_class_init,
165 gst_element_base_class_finalize,
166 (GClassInitFunc) gst_element_class_init,
171 (GInstanceInitFunc) gst_element_init,
175 _type = g_type_register_static (GST_TYPE_OBJECT, "GstElement",
176 &element_info, G_TYPE_FLAG_ABSTRACT);
178 __gst_elementclass_factory =
179 g_quark_from_static_string ("GST_ELEMENTCLASS_FACTORY");
180 g_once_init_leave (&gst_element_type, _type);
182 return gst_element_type;
186 gst_element_class_init (GstElementClass * klass)
188 GObjectClass *gobject_class;
190 gobject_class = (GObjectClass *) klass;
192 parent_class = g_type_class_peek_parent (klass);
195 * GstElement::pad-added:
196 * @gstelement: the object which received the signal
197 * @new_pad: the pad that has been added
199 * a new #GstPad has been added to the element. Note that this signal will
200 * usually be emitted from the context of the streaming thread. Also keep in
201 * mind that if you add new elements to the pipeline in the signal handler
202 * you will need to set them to the desired target state with
203 * gst_element_set_state() or gst_element_sync_state_with_parent().
205 gst_element_signals[PAD_ADDED] =
206 g_signal_new ("pad-added", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
207 G_STRUCT_OFFSET (GstElementClass, pad_added), NULL, NULL,
208 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
210 * GstElement::pad-removed:
211 * @gstelement: the object which received the signal
212 * @old_pad: the pad that has been removed
214 * a #GstPad has been removed from the element
216 gst_element_signals[PAD_REMOVED] =
217 g_signal_new ("pad-removed", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
218 G_STRUCT_OFFSET (GstElementClass, pad_removed), NULL, NULL,
219 g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
221 * GstElement::no-more-pads:
222 * @gstelement: the object which received the signal
224 * This signals that the element will not generate more dynamic pads.
225 * Note that this signal will usually be emitted from the context of
226 * the streaming thread.
228 gst_element_signals[NO_MORE_PADS] =
229 g_signal_new ("no-more-pads", G_TYPE_FROM_CLASS (klass),
230 G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstElementClass, no_more_pads), NULL,
231 NULL, g_cclosure_marshal_generic, G_TYPE_NONE, 0);
233 gobject_class->dispose = gst_element_dispose;
234 gobject_class->finalize = gst_element_finalize;
236 klass->change_state = GST_DEBUG_FUNCPTR (gst_element_change_state_func);
237 klass->set_state = GST_DEBUG_FUNCPTR (gst_element_set_state_func);
238 klass->get_state = GST_DEBUG_FUNCPTR (gst_element_get_state_func);
239 klass->set_clock = GST_DEBUG_FUNCPTR (gst_element_set_clock_func);
240 klass->set_bus = GST_DEBUG_FUNCPTR (gst_element_set_bus_func);
241 klass->query = GST_DEBUG_FUNCPTR (gst_element_default_query);
242 klass->send_event = GST_DEBUG_FUNCPTR (gst_element_default_send_event);
243 klass->numpadtemplates = 0;
244 klass->post_message = GST_DEBUG_FUNCPTR (gst_element_post_message_default);
245 klass->set_context = GST_DEBUG_FUNCPTR (gst_element_set_context_default);
247 klass->elementfactory = NULL;
251 gst_element_base_class_init (gpointer g_class)
253 GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);
254 GList *node, *padtemplates;
256 /* Copy the element details here so elements can inherit the
257 * details from their base class and classes only need to set
258 * the details in class_init instead of base_init */
259 element_class->metadata =
260 element_class->metadata ? gst_structure_copy (element_class->metadata) :
261 gst_structure_new_empty ("metadata");
263 /* Copy the pad templates so elements inherit them
264 * from their base class but elements can add pad templates in class_init
265 * instead of base_init.
267 padtemplates = g_list_copy (element_class->padtemplates);
268 for (node = padtemplates; node != NULL; node = node->next) {
269 GstPadTemplate *tmpl = (GstPadTemplate *) node->data;
270 gst_object_ref (tmpl);
272 element_class->padtemplates = padtemplates;
274 /* set the factory, see gst_element_register() */
275 element_class->elementfactory =
276 g_type_get_qdata (G_TYPE_FROM_CLASS (element_class),
277 __gst_elementclass_factory);
278 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "type %s : factory %p",
279 G_OBJECT_CLASS_NAME (element_class), element_class->elementfactory);
283 gst_element_base_class_finalize (gpointer g_class)
285 GstElementClass *klass = GST_ELEMENT_CLASS (g_class);
287 g_list_foreach (klass->padtemplates, (GFunc) gst_object_unref, NULL);
288 g_list_free (klass->padtemplates);
290 gst_structure_free (klass->metadata);
294 gst_element_init (GstElement * element)
296 GST_STATE (element) = GST_STATE_NULL;
297 GST_STATE_TARGET (element) = GST_STATE_NULL;
298 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
299 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
300 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
302 g_rec_mutex_init (&element->state_lock);
303 g_cond_init (&element->state_cond);
307 * gst_element_release_request_pad:
308 * @element: a #GstElement to release the request pad of.
309 * @pad: the #GstPad to release.
311 * Makes the element free the previously requested pad as obtained
312 * with gst_element_request_pad().
314 * This does not unref the pad. If the pad was created by using
315 * gst_element_request_pad(), gst_element_release_request_pad() needs to be
316 * followed by gst_object_unref() to free the @pad.
321 gst_element_release_request_pad (GstElement * element, GstPad * pad)
323 GstElementClass *oclass;
325 g_return_if_fail (GST_IS_ELEMENT (element));
326 g_return_if_fail (GST_IS_PAD (pad));
327 g_return_if_fail (GST_PAD_PAD_TEMPLATE (pad) == NULL ||
328 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad)) ==
331 oclass = GST_ELEMENT_GET_CLASS (element);
333 /* if the element implements a custom release function we call that, else we
334 * simply remove the pad from the element */
335 if (oclass->release_pad)
336 oclass->release_pad (element, pad);
338 gst_element_remove_pad (element, pad);
342 * gst_element_provide_clock:
343 * @element: a #GstElement to query
345 * Get the clock provided by the given element.
346 * <note>An element is only required to provide a clock in the PAUSED
347 * state. Some elements can provide a clock in other states.</note>
349 * Returns: (transfer full) (nullable): the GstClock provided by the
350 * element or %NULL if no clock could be provided. Unref after usage.
355 gst_element_provide_clock (GstElement * element)
357 GstClock *result = NULL;
358 GstElementClass *oclass;
360 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
362 oclass = GST_ELEMENT_GET_CLASS (element);
364 if (oclass->provide_clock)
365 result = oclass->provide_clock (element);
371 gst_element_set_clock_func (GstElement * element, GstClock * clock)
375 GST_OBJECT_LOCK (element);
376 clock_p = &element->clock;
377 gst_object_replace ((GstObject **) clock_p, (GstObject *) clock);
378 GST_OBJECT_UNLOCK (element);
384 * gst_element_set_clock:
385 * @element: a #GstElement to set the clock for.
386 * @clock: the #GstClock to set for the element.
388 * Sets the clock for the element. This function increases the
389 * refcount on the clock. Any previously set clock on the object
392 * Returns: %TRUE if the element accepted the clock. An element can refuse a
393 * clock when it, for example, is not able to slave its internal clock to the
394 * @clock or when it requires a specific clock to operate.
399 gst_element_set_clock (GstElement * element, GstClock * clock)
401 GstElementClass *oclass;
402 gboolean res = FALSE;
404 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
405 g_return_val_if_fail (clock == NULL || GST_IS_CLOCK (clock), FALSE);
407 oclass = GST_ELEMENT_GET_CLASS (element);
409 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element, "setting clock %p", clock);
411 if (oclass->set_clock)
412 res = oclass->set_clock (element, clock);
418 * gst_element_get_clock:
419 * @element: a #GstElement to get the clock of.
421 * Gets the currently configured clock of the element. This is the clock as was
422 * last set with gst_element_set_clock().
424 * Elements in a pipeline will only have their clock set when the
425 * pipeline is in the PLAYING state.
427 * Returns: (transfer full): the #GstClock of the element. unref after usage.
432 gst_element_get_clock (GstElement * element)
436 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
438 GST_OBJECT_LOCK (element);
439 if ((result = element->clock))
440 gst_object_ref (result);
441 GST_OBJECT_UNLOCK (element);
447 * gst_element_set_base_time:
448 * @element: a #GstElement.
449 * @time: the base time to set.
451 * Set the base time of an element. See gst_element_get_base_time().
456 gst_element_set_base_time (GstElement * element, GstClockTime time)
460 g_return_if_fail (GST_IS_ELEMENT (element));
462 GST_OBJECT_LOCK (element);
463 old = element->base_time;
464 element->base_time = time;
465 GST_OBJECT_UNLOCK (element);
467 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
468 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
469 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
473 * gst_element_get_base_time:
474 * @element: a #GstElement.
476 * Returns the base time of the element. The base time is the
477 * absolute time of the clock when this element was last put to
478 * PLAYING. Subtracting the base time from the clock time gives
479 * the running time of the element.
481 * Returns: the base time of the element.
486 gst_element_get_base_time (GstElement * element)
490 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
492 GST_OBJECT_LOCK (element);
493 result = element->base_time;
494 GST_OBJECT_UNLOCK (element);
500 * gst_element_set_start_time:
501 * @element: a #GstElement.
502 * @time: the base time to set.
504 * Set the start time of an element. The start time of the element is the
505 * running time of the element when it last went to the PAUSED state. In READY
506 * or after a flushing seek, it is set to 0.
508 * Toplevel elements like #GstPipeline will manage the start_time and
509 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
510 * on such a toplevel element will disable the distribution of the base_time to
511 * the children and can be useful if the application manages the base_time
512 * itself, for example if you want to synchronize capture from multiple
513 * pipelines, and you can also ensure that the pipelines have the same clock.
518 gst_element_set_start_time (GstElement * element, GstClockTime time)
522 g_return_if_fail (GST_IS_ELEMENT (element));
524 GST_OBJECT_LOCK (element);
525 old = GST_ELEMENT_START_TIME (element);
526 GST_ELEMENT_START_TIME (element) = time;
527 GST_OBJECT_UNLOCK (element);
529 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
530 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
531 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
535 * gst_element_get_start_time:
536 * @element: a #GstElement.
538 * Returns the start time of the element. The start time is the
539 * running time of the clock when this element was last put to PAUSED.
541 * Usually the start_time is managed by a toplevel element such as
546 * Returns: the start time of the element.
549 gst_element_get_start_time (GstElement * element)
553 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
555 GST_OBJECT_LOCK (element);
556 result = GST_ELEMENT_START_TIME (element);
557 GST_OBJECT_UNLOCK (element);
564 * gst_element_set_index:
565 * @element: a #GstElement.
566 * @index: (transfer none): a #GstIndex.
568 * Set @index on the element. The refcount of the index
569 * will be increased, any previously set index is unreffed.
574 gst_element_set_index (GstElement * element, GstIndex * index)
576 GstElementClass *oclass;
578 g_return_if_fail (GST_IS_ELEMENT (element));
579 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
581 oclass = GST_ELEMENT_GET_CLASS (element);
583 if (oclass->set_index)
584 oclass->set_index (element, index);
588 * gst_element_get_index:
589 * @element: a #GstElement.
591 * Gets the index from the element.
593 * Returns: (transfer full) (nullable): a #GstIndex or %NULL when no
594 * index was set on the element. unref after usage.
599 gst_element_get_index (GstElement * element)
601 GstElementClass *oclass;
602 GstIndex *result = NULL;
604 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
606 oclass = GST_ELEMENT_GET_CLASS (element);
608 if (oclass->get_index)
609 result = oclass->get_index (element);
616 * gst_element_add_pad:
617 * @element: a #GstElement to add the pad to.
618 * @pad: (transfer full): the #GstPad to add to the element.
620 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
621 * see gst_object_set_parent() for refcounting information.
623 * Pads are not automatically activated so elements should perform the needed
624 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
625 * state. See gst_pad_set_active() for more information about activating pads.
627 * The pad and the element should be unlocked when calling this function.
629 * This function will emit the #GstElement::pad-added signal on the element.
631 * Returns: %TRUE if the pad could be added. This function can fail when
632 * a pad with the same name already existed or the pad already had another
638 gst_element_add_pad (GstElement * element, GstPad * pad)
643 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
644 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
646 /* locking pad to look at the name */
647 GST_OBJECT_LOCK (pad);
648 pad_name = g_strdup (GST_PAD_NAME (pad));
649 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
650 GST_STR_NULL (pad_name));
651 flushing = GST_PAD_IS_FLUSHING (pad);
652 GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_NEED_PARENT);
653 GST_OBJECT_UNLOCK (pad);
655 /* then check to see if there's already a pad by that name here */
656 GST_OBJECT_LOCK (element);
657 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
660 /* try to set the pad's parent */
661 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
662 GST_OBJECT_CAST (element))))
665 /* check for flushing pads */
666 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
667 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
668 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
669 "use gst_pad_set_active(pad,TRUE) before adding it.",
670 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
672 GST_OBJECT_LOCK (pad);
673 GST_PAD_UNSET_FLUSHING (pad);
674 GST_OBJECT_UNLOCK (pad);
679 /* add it to the list */
680 switch (gst_pad_get_direction (pad)) {
682 element->srcpads = g_list_append (element->srcpads, pad);
683 element->numsrcpads++;
686 element->sinkpads = g_list_append (element->sinkpads, pad);
687 element->numsinkpads++;
692 element->pads = g_list_append (element->pads, pad);
694 element->pads_cookie++;
695 GST_OBJECT_UNLOCK (element);
697 /* emit the PAD_ADDED signal */
698 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
705 g_critical ("Padname %s is not unique in element %s, not adding",
706 pad_name, GST_ELEMENT_NAME (element));
707 GST_OBJECT_UNLOCK (element);
714 ("Pad %s already has parent when trying to add to element %s",
715 pad_name, GST_ELEMENT_NAME (element));
716 GST_OBJECT_UNLOCK (element);
722 GST_OBJECT_LOCK (pad);
724 ("Trying to add pad %s to element %s, but it has no direction",
725 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
726 GST_OBJECT_UNLOCK (pad);
727 GST_OBJECT_UNLOCK (element);
733 * gst_element_remove_pad:
734 * @element: a #GstElement to remove pad from.
735 * @pad: (transfer full): the #GstPad to remove from the element.
737 * Removes @pad from @element. @pad will be destroyed if it has not been
738 * referenced elsewhere using gst_object_unparent().
740 * This function is used by plugin developers and should not be used
741 * by applications. Pads that were dynamically requested from elements
742 * with gst_element_request_pad() should be released with the
743 * gst_element_release_request_pad() function instead.
745 * Pads are not automatically deactivated so elements should perform the needed
746 * steps to deactivate the pad in case this pad is removed in the PAUSED or
747 * PLAYING state. See gst_pad_set_active() for more information about
750 * The pad and the element should be unlocked when calling this function.
752 * This function will emit the #GstElement::pad-removed signal on the element.
754 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
755 * pad does not belong to the provided element.
760 gst_element_remove_pad (GstElement * element, GstPad * pad)
764 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
765 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
767 /* locking pad to look at the name and parent */
768 GST_OBJECT_LOCK (pad);
769 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
770 GST_STR_NULL (GST_PAD_NAME (pad)));
772 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
774 GST_OBJECT_UNLOCK (pad);
777 if ((peer = gst_pad_get_peer (pad))) {
778 /* window for MT unsafeness, someone else could unlink here
779 * and then we call unlink with wrong pads. The unlink
780 * function would catch this and safely return failed. */
781 if (GST_PAD_IS_SRC (pad))
782 gst_pad_unlink (pad, peer);
784 gst_pad_unlink (peer, pad);
786 gst_object_unref (peer);
789 GST_OBJECT_LOCK (element);
790 /* remove it from the list */
791 switch (gst_pad_get_direction (pad)) {
793 element->srcpads = g_list_remove (element->srcpads, pad);
794 element->numsrcpads--;
797 element->sinkpads = g_list_remove (element->sinkpads, pad);
798 element->numsinkpads--;
801 g_critical ("Removing pad without direction???");
804 element->pads = g_list_remove (element->pads, pad);
806 element->pads_cookie++;
807 GST_OBJECT_UNLOCK (element);
809 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
810 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
812 gst_object_unparent (GST_OBJECT_CAST (pad));
819 /* locking order is element > pad */
820 GST_OBJECT_UNLOCK (pad);
822 GST_OBJECT_LOCK (element);
823 GST_OBJECT_LOCK (pad);
824 g_critical ("Padname %s:%s does not belong to element %s when removing",
825 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
826 GST_OBJECT_UNLOCK (pad);
827 GST_OBJECT_UNLOCK (element);
833 * gst_element_no_more_pads:
834 * @element: a #GstElement
836 * Use this function to signal that the element does not expect any more pads
837 * to show up in the current pipeline. This function should be called whenever
838 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
839 * pad templates use this in combination with autopluggers to figure out that
840 * the element is done initializing its pads.
842 * This function emits the #GstElement::no-more-pads signal.
847 gst_element_no_more_pads (GstElement * element)
849 g_return_if_fail (GST_IS_ELEMENT (element));
851 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
855 pad_compare_name (GstPad * pad1, const gchar * name)
859 GST_OBJECT_LOCK (pad1);
860 result = strcmp (GST_PAD_NAME (pad1), name);
861 GST_OBJECT_UNLOCK (pad1);
867 * gst_element_get_static_pad:
868 * @element: a #GstElement to find a static pad of.
869 * @name: the name of the static #GstPad to retrieve.
871 * Retrieves a pad from @element by name. This version only retrieves
872 * already-existing (i.e. 'static') pads.
874 * Returns: (transfer full) (nullable): the requested #GstPad if
875 * found, otherwise %NULL. unref after usage.
880 gst_element_get_static_pad (GstElement * element, const gchar * name)
883 GstPad *result = NULL;
885 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
886 g_return_val_if_fail (name != NULL, NULL);
888 GST_OBJECT_LOCK (element);
890 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
892 result = GST_PAD_CAST (find->data);
893 gst_object_ref (result);
896 if (result == NULL) {
897 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
898 name, GST_ELEMENT_NAME (element));
900 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
901 GST_ELEMENT_NAME (element), name);
903 GST_OBJECT_UNLOCK (element);
909 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
910 const gchar * name, const GstCaps * caps)
912 GstPad *newpad = NULL;
913 GstElementClass *oclass;
915 oclass = GST_ELEMENT_GET_CLASS (element);
917 #ifndef G_DISABLE_CHECKS
918 /* Some sanity checking here */
922 /* Is this the template name? */
923 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
924 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
926 const gchar *str, *data;
929 /* Otherwise check if it's a valid name for the name template */
930 str = strchr (templ->name_template, '%');
931 g_return_val_if_fail (str != NULL, NULL);
932 g_return_val_if_fail (strncmp (templ->name_template, name,
933 str - templ->name_template) == 0, NULL);
934 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
936 data = name + (str - templ->name_template);
938 /* Can either be %s or %d or %u, do sanity checking for %d */
939 if (*(str + 1) == 'd') {
943 tmp = g_ascii_strtoll (data, &endptr, 10);
944 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
945 && *endptr == '\0', NULL);
946 } else if (*(str + 1) == 'u') {
950 tmp = g_ascii_strtoull (data, &endptr, 10);
951 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
955 pad = gst_element_get_static_pad (element, name);
957 gst_object_unref (pad);
958 /* FIXME 2.0: Change this to g_return_val_if_fail() */
959 g_critical ("Element %s already has a pad named %s, the behaviour of "
960 " gst_element_get_request_pad() for existing pads is undefined!",
961 GST_ELEMENT_NAME (element), name);
966 if (oclass->request_new_pad)
967 newpad = (oclass->request_new_pad) (element, templ, name, caps);
970 gst_object_ref (newpad);
976 * gst_element_get_request_pad:
977 * @element: a #GstElement to find a request pad of.
978 * @name: the name of the request #GstPad to retrieve.
980 * Retrieves a pad from the element by name (e.g. "src_\%d"). This version only
981 * retrieves request pads. The pad should be released with
982 * gst_element_release_request_pad().
984 * This method is slower than manually getting the pad template and calling
985 * gst_element_request_pad() if the pads should have a specific name (e.g.
986 * @name is "src_1" instead of "src_\%u").
988 * Returns: (transfer full) (nullable): requested #GstPad if found,
989 * otherwise %NULL. Release after usage.
992 gst_element_get_request_pad (GstElement * element, const gchar * name)
994 GstPadTemplate *templ = NULL;
996 const gchar *req_name = NULL;
997 gboolean templ_found = FALSE;
1000 gchar *str, *endptr = NULL;
1001 GstElementClass *class;
1003 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1004 g_return_val_if_fail (name != NULL, NULL);
1006 class = GST_ELEMENT_GET_CLASS (element);
1008 /* if the name contains a %, we assume it's the complete template name. Get
1009 * the template and try to get a pad */
1010 if (strstr (name, "%")) {
1011 templ = gst_element_class_get_request_pad_template (class, name);
1016 /* there is no % in the name, try to find a matching template */
1017 list = class->padtemplates;
1018 while (!templ_found && list) {
1019 templ = (GstPadTemplate *) list->data;
1020 if (templ->presence == GST_PAD_REQUEST) {
1021 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1022 templ->name_template);
1023 /* see if we find an exact match */
1024 if (strcmp (name, templ->name_template) == 0) {
1029 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1030 and %d and %u, occurring at the end of the name_template, are the only
1032 else if ((str = strchr (templ->name_template, '%'))
1033 && strncmp (templ->name_template, name,
1034 str - templ->name_template) == 0
1035 && strlen (name) > str - templ->name_template) {
1036 data = name + (str - templ->name_template);
1037 if (*(str + 1) == 'd') {
1041 tmp = strtol (data, &endptr, 10);
1042 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1048 } else if (*(str + 1) == 'u') {
1052 tmp = strtoul (data, &endptr, 10);
1053 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1073 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1079 * gst_element_request_pad: (virtual request_new_pad)
1080 * @element: a #GstElement to find a request pad of.
1081 * @templ: a #GstPadTemplate of which we want a pad of.
1082 * @name: (transfer none) (allow-none): the name of the request #GstPad
1083 * to retrieve. Can be %NULL.
1084 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1085 * request. Can be %NULL.
1087 * Retrieves a request pad from the element according to the provided template.
1088 * Pad templates can be looked up using
1089 * gst_element_factory_get_static_pad_templates().
1091 * The pad should be released with gst_element_release_request_pad().
1093 * Returns: (transfer full) (nullable): requested #GstPad if found,
1094 * otherwise %NULL. Release after usage.
1097 gst_element_request_pad (GstElement * element,
1098 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1100 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1101 g_return_val_if_fail (templ != NULL, NULL);
1102 g_return_val_if_fail (templ->presence == GST_PAD_REQUEST, NULL);
1104 return _gst_element_request_pad (element, templ, name, caps);
1107 static GstIterator *
1108 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1110 GstIterator *result;
1112 GST_OBJECT_LOCK (element);
1113 result = gst_iterator_new_list (GST_TYPE_PAD,
1114 GST_OBJECT_GET_LOCK (element),
1115 &element->pads_cookie, padlist, (GObject *) element, NULL);
1116 GST_OBJECT_UNLOCK (element);
1122 * gst_element_iterate_pads:
1123 * @element: a #GstElement to iterate pads of.
1125 * Retrieves an iterator of @element's pads. The iterator should
1126 * be freed after usage. Also more specialized iterators exists such as
1127 * gst_element_iterate_src_pads() or gst_element_iterate_sink_pads().
1129 * The order of pads returned by the iterator will be the order in which
1130 * the pads were added to the element.
1132 * Returns: (transfer full): the #GstIterator of #GstPad.
1137 gst_element_iterate_pads (GstElement * element)
1139 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1141 return gst_element_iterate_pad_list (element, &element->pads);
1145 * gst_element_iterate_src_pads:
1146 * @element: a #GstElement.
1148 * Retrieves an iterator of @element's source pads.
1150 * The order of pads returned by the iterator will be the order in which
1151 * the pads were added to the element.
1153 * Returns: (transfer full): the #GstIterator of #GstPad.
1158 gst_element_iterate_src_pads (GstElement * element)
1160 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1162 return gst_element_iterate_pad_list (element, &element->srcpads);
1166 * gst_element_iterate_sink_pads:
1167 * @element: a #GstElement.
1169 * Retrieves an iterator of @element's sink pads.
1171 * The order of pads returned by the iterator will be the order in which
1172 * the pads were added to the element.
1174 * Returns: (transfer full): the #GstIterator of #GstPad.
1179 gst_element_iterate_sink_pads (GstElement * element)
1181 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1183 return gst_element_iterate_pad_list (element, &element->sinkpads);
1187 * gst_element_class_add_pad_template:
1188 * @klass: the #GstElementClass to add the pad template to.
1189 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1191 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1192 * functions of classes. If a pad template with the same name as an already
1193 * existing one is added the old one is replaced by the new one.
1197 gst_element_class_add_pad_template (GstElementClass * klass,
1198 GstPadTemplate * templ)
1200 GList *template_list = klass->padtemplates;
1202 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1203 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1205 /* If we already have a pad template with the same name replace the
1207 while (template_list) {
1208 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1210 /* Found pad with the same name, replace and return */
1211 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1212 gst_object_unref (padtempl);
1213 template_list->data = templ;
1216 template_list = g_list_next (template_list);
1219 /* Take ownership of the floating ref */
1220 gst_object_ref_sink (templ);
1222 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1223 klass->numpadtemplates++;
1227 * gst_element_class_add_metadata:
1228 * @klass: class to set metadata for
1229 * @key: the key to set
1230 * @value: the value to set
1232 * Set @key with @value as metadata in @klass.
1235 gst_element_class_add_metadata (GstElementClass * klass,
1236 const gchar * key, const gchar * value)
1238 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1239 g_return_if_fail (key != NULL);
1240 g_return_if_fail (value != NULL);
1242 gst_structure_set ((GstStructure *) klass->metadata,
1243 key, G_TYPE_STRING, value, NULL);
1247 * gst_element_class_add_static_metadata:
1248 * @klass: class to set metadata for
1249 * @key: the key to set
1250 * @value: the value to set
1252 * Set @key with @value as metadata in @klass.
1254 * Same as gst_element_class_add_metadata(), but @value must be a static string
1255 * or an inlined string, as it will not be copied. (GStreamer plugins will
1256 * be made resident once loaded, so this function can be used even from
1257 * dynamically loaded plugins.)
1260 gst_element_class_add_static_metadata (GstElementClass * klass,
1261 const gchar * key, const gchar * value)
1263 GValue val = G_VALUE_INIT;
1265 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1266 g_return_if_fail (key != NULL);
1267 g_return_if_fail (value != NULL);
1269 g_value_init (&val, G_TYPE_STRING);
1270 g_value_set_static_string (&val, value);
1271 gst_structure_take_value ((GstStructure *) klass->metadata, key, &val);
1275 * gst_element_class_set_metadata:
1276 * @klass: class to set metadata for
1277 * @longname: The long English name of the element. E.g. "File Sink"
1278 * @classification: String describing the type of element, as an unordered list
1279 * separated with slashes ('/'). See draft-klass.txt of the design docs
1280 * for more details and common types. E.g: "Sink/File"
1281 * @description: Sentence describing the purpose of the element.
1282 * E.g: "Write stream to a file"
1283 * @author: Name and contact details of the author(s). Use \n to separate
1284 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1286 * Sets the detailed information for a #GstElementClass.
1287 * <note>This function is for use in _class_init functions only.</note>
1290 gst_element_class_set_metadata (GstElementClass * klass,
1291 const gchar * longname, const gchar * classification,
1292 const gchar * description, const gchar * author)
1294 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1295 g_return_if_fail (longname != NULL && *longname != '\0');
1296 g_return_if_fail (classification != NULL && *classification != '\0');
1297 g_return_if_fail (description != NULL && *description != '\0');
1298 g_return_if_fail (author != NULL && *author != '\0');
1300 gst_structure_id_set ((GstStructure *) klass->metadata,
1301 GST_QUARK (ELEMENT_METADATA_LONGNAME), G_TYPE_STRING, longname,
1302 GST_QUARK (ELEMENT_METADATA_KLASS), G_TYPE_STRING, classification,
1303 GST_QUARK (ELEMENT_METADATA_DESCRIPTION), G_TYPE_STRING, description,
1304 GST_QUARK (ELEMENT_METADATA_AUTHOR), G_TYPE_STRING, author, NULL);
1308 * gst_element_class_set_static_metadata:
1309 * @klass: class to set metadata for
1310 * @longname: The long English name of the element. E.g. "File Sink"
1311 * @classification: String describing the type of element, as an unordered list
1312 * separated with slashes ('/'). See draft-klass.txt of the design docs
1313 * for more details and common types. E.g: "Sink/File"
1314 * @description: Sentence describing the purpose of the element.
1315 * E.g: "Write stream to a file"
1316 * @author: Name and contact details of the author(s). Use \n to separate
1317 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1319 * Sets the detailed information for a #GstElementClass.
1320 * <note>This function is for use in _class_init functions only.</note>
1322 * Same as gst_element_class_set_metadata(), but @longname, @classification,
1323 * @description, and @author must be static strings or inlined strings, as
1324 * they will not be copied. (GStreamer plugins will be made resident once
1325 * loaded, so this function can be used even from dynamically loaded plugins.)
1328 gst_element_class_set_static_metadata (GstElementClass * klass,
1329 const gchar * longname, const gchar * classification,
1330 const gchar * description, const gchar * author)
1332 GstStructure *s = (GstStructure *) klass->metadata;
1333 GValue val = G_VALUE_INIT;
1335 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1336 g_return_if_fail (longname != NULL && *longname != '\0');
1337 g_return_if_fail (classification != NULL && *classification != '\0');
1338 g_return_if_fail (description != NULL && *description != '\0');
1339 g_return_if_fail (author != NULL && *author != '\0');
1341 g_value_init (&val, G_TYPE_STRING);
1343 g_value_set_static_string (&val, longname);
1344 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_LONGNAME), &val);
1346 g_value_set_static_string (&val, classification);
1347 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_KLASS), &val);
1349 g_value_set_static_string (&val, description);
1350 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_DESCRIPTION),
1353 g_value_set_static_string (&val, author);
1354 gst_structure_id_take_value (s, GST_QUARK (ELEMENT_METADATA_AUTHOR), &val);
1358 * gst_element_class_get_metadata:
1359 * @klass: class to get metadata for
1360 * @key: the key to get
1362 * Get metadata with @key in @klass.
1364 * Returns: the metadata for @key.
1367 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1369 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1370 g_return_val_if_fail (key != NULL, NULL);
1372 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1376 * gst_element_class_get_pad_template_list:
1377 * @element_class: a #GstElementClass to get pad templates of.
1379 * Retrieves a list of the pad templates associated with @element_class. The
1380 * list must not be modified by the calling code.
1381 * <note>If you use this function in the #GInstanceInitFunc of an object class
1382 * that has subclasses, make sure to pass the g_class parameter of the
1383 * #GInstanceInitFunc here.</note>
1385 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1389 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1391 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1393 return element_class->padtemplates;
1397 * gst_element_class_get_pad_template:
1398 * @element_class: a #GstElementClass to get the pad template of.
1399 * @name: the name of the #GstPadTemplate to get.
1401 * Retrieves a padtemplate from @element_class with the given name.
1402 * <note>If you use this function in the #GInstanceInitFunc of an object class
1403 * that has subclasses, make sure to pass the g_class parameter of the
1404 * #GInstanceInitFunc here.</note>
1406 * Returns: (transfer none) (nullable): the #GstPadTemplate with the
1407 * given name, or %NULL if none was found. No unreferencing is
1411 gst_element_class_get_pad_template (GstElementClass *
1412 element_class, const gchar * name)
1416 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1417 g_return_val_if_fail (name != NULL, NULL);
1419 padlist = element_class->padtemplates;
1422 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1424 if (strcmp (padtempl->name_template, name) == 0)
1427 padlist = g_list_next (padlist);
1433 static GstPadTemplate *
1434 gst_element_class_get_request_pad_template (GstElementClass *
1435 element_class, const gchar * name)
1437 GstPadTemplate *tmpl;
1439 tmpl = gst_element_class_get_pad_template (element_class, name);
1440 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1446 /* get a random pad on element of the given direction.
1447 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1450 gst_element_get_random_pad (GstElement * element,
1451 gboolean need_linked, GstPadDirection dir)
1453 GstPad *result = NULL;
1456 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1460 GST_OBJECT_LOCK (element);
1461 pads = element->srcpads;
1464 GST_OBJECT_LOCK (element);
1465 pads = element->sinkpads;
1468 goto wrong_direction;
1470 for (; pads; pads = g_list_next (pads)) {
1471 GstPad *pad = GST_PAD_CAST (pads->data);
1473 GST_OBJECT_LOCK (pad);
1474 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1475 GST_DEBUG_PAD_NAME (pad));
1477 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1478 /* if we require a linked pad, and it is not linked, continue the
1480 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1481 GST_DEBUG_PAD_NAME (pad));
1482 GST_OBJECT_UNLOCK (pad);
1485 /* found a pad, stop search */
1486 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1487 GST_DEBUG_PAD_NAME (pad));
1488 GST_OBJECT_UNLOCK (pad);
1494 gst_object_ref (result);
1496 GST_OBJECT_UNLOCK (element);
1500 /* ERROR handling */
1503 g_warning ("unknown pad direction %d", dir);
1509 gst_element_default_send_event (GstElement * element, GstEvent * event)
1511 gboolean result = FALSE;
1514 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1515 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK) :
1516 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC);
1519 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1520 "pushing %s event to random %s pad %s:%s",
1521 GST_EVENT_TYPE_NAME (event),
1522 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1523 GST_DEBUG_PAD_NAME (pad));
1525 result = gst_pad_send_event (pad, event);
1526 gst_object_unref (pad);
1528 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1529 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1530 gst_event_unref (event);
1536 * gst_element_send_event:
1537 * @element: a #GstElement to send the event to.
1538 * @event: (transfer full): the #GstEvent to send to the element.
1540 * Sends an event to an element. If the element doesn't implement an
1541 * event handler, the event will be pushed on a random linked sink pad for
1542 * downstream events or a random linked source pad for upstream events.
1544 * This function takes ownership of the provided event so you should
1545 * gst_event_ref() it if you want to reuse the event after this call.
1549 * Returns: %TRUE if the event was handled. Events that trigger a preroll (such
1550 * as flushing seeks and steps) will emit %GST_MESSAGE_ASYNC_DONE.
1553 gst_element_send_event (GstElement * element, GstEvent * event)
1555 GstElementClass *oclass;
1556 gboolean result = FALSE;
1558 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1559 g_return_val_if_fail (event != NULL, FALSE);
1561 oclass = GST_ELEMENT_GET_CLASS (element);
1563 GST_STATE_LOCK (element);
1564 if (oclass->send_event) {
1565 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1566 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1567 result = oclass->send_event (element, event);
1569 GST_STATE_UNLOCK (element);
1576 * @element: a #GstElement to send the event to.
1577 * @rate: The new playback rate
1578 * @format: The format of the seek values
1579 * @flags: The optional seek flags.
1580 * @start_type: The type and flags for the new start position
1581 * @start: The value of the new start position
1582 * @stop_type: The type and flags for the new stop position
1583 * @stop: The value of the new stop position
1585 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1586 * the parameters. The seek event is sent to the element using
1587 * gst_element_send_event().
1591 * Returns: %TRUE if the event was handled. Flushing seeks will trigger a
1592 * preroll, which will emit %GST_MESSAGE_ASYNC_DONE.
1595 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1596 GstSeekFlags flags, GstSeekType start_type, gint64 start,
1597 GstSeekType stop_type, gint64 stop)
1602 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1605 gst_event_new_seek (rate, format, flags, start_type, start, stop_type,
1607 result = gst_element_send_event (element, event);
1613 gst_element_default_query (GstElement * element, GstQuery * query)
1615 gboolean result = FALSE;
1618 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1620 result = gst_pad_query (pad, query);
1622 gst_object_unref (pad);
1624 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1626 GstPad *peer = gst_pad_get_peer (pad);
1629 result = gst_pad_query (peer, query);
1631 gst_object_unref (peer);
1633 gst_object_unref (pad);
1640 * gst_element_query:
1641 * @element: a #GstElement to perform the query on.
1642 * @query: (transfer none): the #GstQuery.
1644 * Performs a query on the given element.
1646 * For elements that don't implement a query handler, this function
1647 * forwards the query to a random srcpad or to the peer of a
1648 * random linked sinkpad of this element.
1650 * Please note that some queries might need a running pipeline to work.
1652 * Returns: %TRUE if the query could be performed.
1657 gst_element_query (GstElement * element, GstQuery * query)
1659 GstElementClass *klass;
1660 gboolean res = FALSE;
1662 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1663 g_return_val_if_fail (query != NULL, FALSE);
1665 GST_TRACER_ELEMENT_QUERY_PRE (element, query);
1667 klass = GST_ELEMENT_GET_CLASS (element);
1669 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1670 GST_ELEMENT_NAME (element));
1671 res = klass->query (element, query);
1674 GST_TRACER_ELEMENT_QUERY_POST (element, res);
1679 gst_element_post_message_default (GstElement * element, GstMessage * message)
1682 gboolean result = FALSE;
1684 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1685 g_return_val_if_fail (message != NULL, FALSE);
1687 GST_OBJECT_LOCK (element);
1690 if (G_UNLIKELY (bus == NULL))
1693 gst_object_ref (bus);
1694 GST_OBJECT_UNLOCK (element);
1696 /* we release the element lock when posting the message so that any
1697 * (synchronous) message handlers can operate on the element */
1698 result = gst_bus_post (bus, message);
1699 gst_object_unref (bus);
1706 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1707 "not posting message %p: no bus", message);
1708 GST_OBJECT_UNLOCK (element);
1709 gst_message_unref (message);
1715 * gst_element_post_message:
1716 * @element: a #GstElement posting the message
1717 * @message: (transfer full): a #GstMessage to post
1719 * Post a message on the element's #GstBus. This function takes ownership of the
1720 * message; if you want to access the message after this call, you should add an
1721 * additional reference before calling.
1723 * Returns: %TRUE if the message was successfully posted. The function returns
1724 * %FALSE if the element did not have a bus.
1729 gst_element_post_message (GstElement * element, GstMessage * message)
1731 GstElementClass *klass;
1732 gboolean res = FALSE;
1734 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1735 g_return_val_if_fail (message != NULL, FALSE);
1737 GST_TRACER_ELEMENT_POST_MESSAGE_PRE (element, message);
1739 klass = GST_ELEMENT_GET_CLASS (element);
1740 if (klass->post_message)
1741 res = klass->post_message (element, message);
1743 GST_TRACER_ELEMENT_POST_MESSAGE_POST (element, res);
1748 * _gst_element_error_printf:
1749 * @format: (allow-none): the printf-like format to use, or %NULL
1751 * This function is only used internally by the gst_element_error() macro.
1753 * Returns: (transfer full) (nullable): a newly allocated string, or
1754 * %NULL if the format was %NULL or ""
1759 _gst_element_error_printf (const gchar * format, ...)
1770 va_start (args, format);
1772 len = __gst_vasprintf (&buffer, format, args);
1783 * gst_element_message_full:
1784 * @element: a #GstElement to send message from
1785 * @type: the #GstMessageType
1786 * @domain: the GStreamer GError domain this message belongs to
1787 * @code: the GError code belonging to the domain
1788 * @text: (allow-none) (transfer full): an allocated text string to be used
1789 * as a replacement for the default message connected to code,
1791 * @debug: (allow-none) (transfer full): an allocated debug message to be
1792 * used as a replacement for the default debugging information,
1794 * @file: the source code file where the error was generated
1795 * @function: the source code function where the error was generated
1796 * @line: the source code line where the error was generated
1798 * Post an error, warning or info message on the bus from inside an element.
1800 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1801 * #GST_MESSAGE_INFO.
1805 void gst_element_message_full
1806 (GstElement * element, GstMessageType type,
1807 GQuark domain, gint code, gchar * text,
1808 gchar * debug, const gchar * file, const gchar * function, gint line)
1810 GError *gerror = NULL;
1814 gboolean has_debug = TRUE;
1815 GstMessage *message = NULL;
1818 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1819 g_return_if_fail (GST_IS_ELEMENT (element));
1820 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1821 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1823 /* check if we send the given text or the default error text */
1824 if ((text == NULL) || (text[0] == 0)) {
1825 /* text could have come from g_strdup_printf (""); */
1827 sent_text = gst_error_get_message (domain, code);
1831 /* construct a sent_debug with extra information from source */
1832 if ((debug == NULL) || (debug[0] == 0)) {
1833 /* debug could have come from g_strdup_printf (""); */
1837 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1839 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1840 file, line, function, name, debug);
1842 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1843 file, line, function, name);
1847 /* create gerror and post message */
1848 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1850 gerror = g_error_new_literal (domain, code, sent_text);
1853 case GST_MESSAGE_ERROR:
1855 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1857 case GST_MESSAGE_WARNING:
1858 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1861 case GST_MESSAGE_INFO:
1862 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1866 g_assert_not_reached ();
1869 gst_element_post_message (element, message);
1871 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1872 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1875 g_error_free (gerror);
1876 g_free (sent_debug);
1881 * gst_element_is_locked_state:
1882 * @element: a #GstElement.
1884 * Checks if the state of an element is locked.
1885 * If the state of an element is locked, state changes of the parent don't
1886 * affect the element.
1887 * This way you can leave currently unused elements inside bins. Just lock their
1888 * state before changing the state from #GST_STATE_NULL.
1892 * Returns: %TRUE, if the element's state is locked.
1895 gst_element_is_locked_state (GstElement * element)
1899 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1901 GST_OBJECT_LOCK (element);
1902 result = GST_ELEMENT_IS_LOCKED_STATE (element);
1903 GST_OBJECT_UNLOCK (element);
1909 * gst_element_set_locked_state:
1910 * @element: a #GstElement
1911 * @locked_state: %TRUE to lock the element's state
1913 * Locks the state of an element, so state changes of the parent don't affect
1914 * this element anymore.
1918 * Returns: %TRUE if the state was changed, %FALSE if bad parameters were given
1919 * or the elements state-locking needed no change.
1922 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1926 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1928 GST_OBJECT_LOCK (element);
1929 old = GST_ELEMENT_IS_LOCKED_STATE (element);
1931 if (G_UNLIKELY (old == locked_state))
1935 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1936 GST_ELEMENT_NAME (element));
1937 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1939 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1940 GST_ELEMENT_NAME (element));
1941 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1943 GST_OBJECT_UNLOCK (element);
1949 GST_CAT_DEBUG (GST_CAT_STATES,
1950 "elements %s was already in locked state %d",
1951 GST_ELEMENT_NAME (element), old);
1952 GST_OBJECT_UNLOCK (element);
1959 * gst_element_sync_state_with_parent:
1960 * @element: a #GstElement.
1962 * Tries to change the state of the element to the same as its parent.
1963 * If this function returns %FALSE, the state of element is undefined.
1965 * Returns: %TRUE, if the element's state could be synced to the parent's state.
1970 gst_element_sync_state_with_parent (GstElement * element)
1974 GstStateChangeReturn ret;
1976 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1978 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1979 GstState parent_current, parent_pending;
1981 GST_OBJECT_LOCK (parent);
1982 parent_current = GST_STATE (parent);
1983 parent_pending = GST_STATE_PENDING (parent);
1984 GST_OBJECT_UNLOCK (parent);
1986 /* set to pending if there is one, else we set it to the current state of
1988 if (parent_pending != GST_STATE_VOID_PENDING)
1989 target = parent_pending;
1991 target = parent_current;
1993 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1994 "syncing state (%s) to parent %s %s (%s, %s)",
1995 gst_element_state_get_name (GST_STATE (element)),
1996 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1997 gst_element_state_get_name (parent_current),
1998 gst_element_state_get_name (parent_pending));
2000 ret = gst_element_set_state (element, target);
2001 if (ret == GST_STATE_CHANGE_FAILURE)
2004 gst_object_unref (parent);
2008 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
2015 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2016 "syncing state failed (%s)",
2017 gst_element_state_change_return_get_name (ret));
2018 gst_object_unref (parent);
2024 static GstStateChangeReturn
2025 gst_element_get_state_func (GstElement * element,
2026 GstState * state, GstState * pending, GstClockTime timeout)
2028 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2029 GstState old_pending;
2031 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2032 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2034 GST_OBJECT_LOCK (element);
2035 ret = GST_STATE_RETURN (element);
2036 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2037 gst_element_state_change_return_get_name (ret));
2039 /* we got an error, report immediately */
2040 if (ret == GST_STATE_CHANGE_FAILURE)
2043 /* we got no_preroll, report immediately */
2044 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2047 /* no need to wait async if we are not async */
2048 if (ret != GST_STATE_CHANGE_ASYNC)
2051 old_pending = GST_STATE_PENDING (element);
2052 if (old_pending != GST_STATE_VOID_PENDING) {
2056 /* get cookie to detect state changes during waiting */
2057 cookie = element->state_cookie;
2059 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2060 "waiting for element to commit state");
2062 /* we have a pending state change, wait for it to complete */
2063 if (timeout != GST_CLOCK_TIME_NONE) {
2065 /* make timeout absolute */
2066 end_time = g_get_monotonic_time () + (timeout / 1000);
2067 signaled = GST_STATE_WAIT_UNTIL (element, end_time);
2069 GST_STATE_WAIT (element);
2074 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2075 /* timeout triggered */
2076 ret = GST_STATE_CHANGE_ASYNC;
2078 if (cookie != element->state_cookie)
2081 /* could be success or failure */
2082 if (old_pending == GST_STATE (element)) {
2083 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2084 ret = GST_STATE_CHANGE_SUCCESS;
2086 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2087 ret = GST_STATE_CHANGE_FAILURE;
2090 /* if nothing is pending anymore we can return SUCCESS */
2091 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2092 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2093 ret = GST_STATE_CHANGE_SUCCESS;
2099 *state = GST_STATE (element);
2101 *pending = GST_STATE_PENDING (element);
2103 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2104 "state current: %s, pending: %s, result: %s",
2105 gst_element_state_get_name (GST_STATE (element)),
2106 gst_element_state_get_name (GST_STATE_PENDING (element)),
2107 gst_element_state_change_return_get_name (ret));
2108 GST_OBJECT_UNLOCK (element);
2115 *state = GST_STATE_VOID_PENDING;
2117 *pending = GST_STATE_VOID_PENDING;
2119 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2121 GST_OBJECT_UNLOCK (element);
2123 return GST_STATE_CHANGE_FAILURE;
2128 * gst_element_get_state:
2129 * @element: a #GstElement to get the state of.
2130 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2132 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2133 * state. Can be %NULL.
2134 * @timeout: a #GstClockTime to specify the timeout for an async
2135 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2137 * Gets the state of the element.
2139 * For elements that performed an ASYNC state change, as reported by
2140 * gst_element_set_state(), this function will block up to the
2141 * specified timeout value for the state change to complete.
2142 * If the element completes the state change or goes into
2143 * an error, this function returns immediately with a return value of
2144 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2146 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2147 * returns the current and pending state immediately.
2149 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2150 * successfully changed its state but is not able to provide data yet.
2151 * This mostly happens for live sources that only produce data in
2152 * %GST_STATE_PLAYING. While the state change return is equivalent to
2153 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2154 * some sink elements might not be able to complete their state change because
2155 * an element is not producing data to complete the preroll. When setting the
2156 * element to playing, the preroll will complete and playback will start.
2158 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2159 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2160 * element is still performing a state change or
2161 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2165 GstStateChangeReturn
2166 gst_element_get_state (GstElement * element,
2167 GstState * state, GstState * pending, GstClockTime timeout)
2169 GstElementClass *oclass;
2170 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2172 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2174 oclass = GST_ELEMENT_GET_CLASS (element);
2176 if (oclass->get_state)
2177 result = (oclass->get_state) (element, state, pending, timeout);
2183 * gst_element_abort_state:
2184 * @element: a #GstElement to abort the state of.
2186 * Abort the state change of the element. This function is used
2187 * by elements that do asynchronous state changes and find out
2188 * something is wrong.
2190 * This function should be called with the STATE_LOCK held.
2195 gst_element_abort_state (GstElement * element)
2199 #ifndef GST_DISABLE_GST_DEBUG
2203 g_return_if_fail (GST_IS_ELEMENT (element));
2205 GST_OBJECT_LOCK (element);
2206 pending = GST_STATE_PENDING (element);
2208 if (pending == GST_STATE_VOID_PENDING ||
2209 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2210 goto nothing_aborted;
2212 #ifndef GST_DISABLE_GST_DEBUG
2213 old_state = GST_STATE (element);
2215 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2216 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2217 gst_element_state_get_name (pending));
2221 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2223 GST_STATE_BROADCAST (element);
2224 GST_OBJECT_UNLOCK (element);
2230 GST_OBJECT_UNLOCK (element);
2235 /* Not static because GstBin has manual state handling too */
2237 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2238 GstState newstate, GstState pending)
2240 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2241 GstMessage *message;
2243 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2244 "notifying about state-changed %s to %s (%s pending)",
2245 gst_element_state_get_name (oldstate),
2246 gst_element_state_get_name (newstate),
2247 gst_element_state_get_name (pending));
2249 if (klass->state_changed)
2250 klass->state_changed (element, oldstate, newstate, pending);
2252 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2253 oldstate, newstate, pending);
2254 gst_element_post_message (element, message);
2258 * gst_element_continue_state:
2259 * @element: a #GstElement to continue the state change of.
2260 * @ret: The previous state return value
2262 * Commit the state change of the element and proceed to the next
2263 * pending state if any. This function is used
2264 * by elements that do asynchronous state changes.
2265 * The core will normally call this method automatically when an
2266 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2268 * If after calling this method the element still has not reached
2269 * the pending state, the next state change is performed.
2271 * This method is used internally and should normally not be called by plugins
2274 * Returns: The result of the commit state change.
2278 GstStateChangeReturn
2279 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2281 GstStateChangeReturn old_ret;
2282 GstState old_state, old_next;
2283 GstState current, next, pending;
2284 GstStateChange transition;
2286 GST_OBJECT_LOCK (element);
2287 old_ret = GST_STATE_RETURN (element);
2288 GST_STATE_RETURN (element) = ret;
2289 pending = GST_STATE_PENDING (element);
2291 /* check if there is something to commit */
2292 if (pending == GST_STATE_VOID_PENDING)
2293 goto nothing_pending;
2295 old_state = GST_STATE (element);
2296 /* this is the state we should go to next */
2297 old_next = GST_STATE_NEXT (element);
2298 /* update current state */
2299 current = GST_STATE (element) = old_next;
2301 /* see if we reached the final state */
2302 if (pending == current)
2305 next = GST_STATE_GET_NEXT (current, pending);
2306 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2308 GST_STATE_NEXT (element) = next;
2310 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2311 GST_OBJECT_UNLOCK (element);
2313 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2314 "committing state from %s to %s, pending %s, next %s",
2315 gst_element_state_get_name (old_state),
2316 gst_element_state_get_name (old_next),
2317 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2319 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2321 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2322 "continue state change %s to %s, final %s",
2323 gst_element_state_get_name (current),
2324 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2326 ret = gst_element_change_state (element, transition);
2332 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2333 GST_OBJECT_UNLOCK (element);
2338 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2339 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2341 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2342 "completed state change to %s", gst_element_state_get_name (pending));
2343 GST_OBJECT_UNLOCK (element);
2345 /* don't post silly messages with the same state. This can happen
2346 * when an element state is changed to what it already was. For bins
2347 * this can be the result of a lost state, which we check with the
2348 * previous return value.
2349 * We do signal the cond though as a _get_state() might be blocking
2351 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2352 _priv_gst_element_state_changed (element, old_state, old_next,
2353 GST_STATE_VOID_PENDING);
2355 GST_STATE_BROADCAST (element);
2362 * gst_element_lost_state:
2363 * @element: a #GstElement the state is lost of
2365 * Brings the element to the lost state. The current state of the
2366 * element is copied to the pending state so that any call to
2367 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2369 * An ASYNC_START message is posted. If the element was PLAYING, it will
2370 * go to PAUSED. The element will be restored to its PLAYING state by
2371 * the parent pipeline when it prerolls again.
2373 * This is mostly used for elements that lost their preroll buffer
2374 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2375 * they will go to their pending state again when a new preroll buffer is
2376 * queued. This function can only be called when the element is currently
2377 * not in error or an async state change.
2379 * This function is used internally and should normally not be called from
2380 * plugins or applications.
2383 gst_element_lost_state (GstElement * element)
2385 GstState old_state, new_state;
2386 GstMessage *message;
2388 g_return_if_fail (GST_IS_ELEMENT (element));
2390 GST_OBJECT_LOCK (element);
2391 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2394 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2395 goto only_async_start;
2397 old_state = GST_STATE (element);
2399 /* when we were PLAYING, the new state is PAUSED. We will also not
2400 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2401 * when we preroll. */
2402 if (old_state > GST_STATE_PAUSED)
2403 new_state = GST_STATE_PAUSED;
2405 new_state = old_state;
2407 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2408 "lost state of %s to %s", gst_element_state_get_name (old_state),
2409 gst_element_state_get_name (new_state));
2411 GST_STATE (element) = new_state;
2412 GST_STATE_NEXT (element) = new_state;
2413 GST_STATE_PENDING (element) = new_state;
2414 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2415 GST_OBJECT_UNLOCK (element);
2417 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2419 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2420 gst_element_post_message (element, message);
2426 GST_OBJECT_UNLOCK (element);
2431 GST_OBJECT_UNLOCK (element);
2433 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2434 gst_element_post_message (element, message);
2440 * gst_element_set_state:
2441 * @element: a #GstElement to change state of.
2442 * @state: the element's new #GstState.
2444 * Sets the state of the element. This function will try to set the
2445 * requested state by going through all the intermediary states and calling
2446 * the class's state change function for each.
2448 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2449 * element will perform the remainder of the state change asynchronously in
2451 * An application can use gst_element_get_state() to wait for the completion
2452 * of the state change or it can wait for a %GST_MESSAGE_ASYNC_DONE or
2453 * %GST_MESSAGE_STATE_CHANGED on the bus.
2455 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2456 * #GST_STATE_CHANGE_ASYNC.
2458 * Returns: Result of the state change using #GstStateChangeReturn.
2462 GstStateChangeReturn
2463 gst_element_set_state (GstElement * element, GstState state)
2465 GstElementClass *oclass;
2466 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2468 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2470 oclass = GST_ELEMENT_GET_CLASS (element);
2472 if (oclass->set_state)
2473 result = (oclass->set_state) (element, state);
2479 * default set state function, calculates the next state based
2480 * on current state and calls the change_state function
2482 static GstStateChangeReturn
2483 gst_element_set_state_func (GstElement * element, GstState state)
2485 GstState current, next, old_pending;
2486 GstStateChangeReturn ret;
2487 GstStateChange transition;
2488 GstStateChangeReturn old_ret;
2490 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2492 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2493 gst_element_state_get_name (state));
2495 /* state lock is taken to protect the set_state() and get_state()
2496 * procedures, it does not lock any variables. */
2497 GST_STATE_LOCK (element);
2499 /* now calculate how to get to the new state */
2500 GST_OBJECT_LOCK (element);
2501 old_ret = GST_STATE_RETURN (element);
2502 /* previous state change returned an error, remove all pending
2503 * and next states */
2504 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2505 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2506 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2507 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2510 current = GST_STATE (element);
2511 next = GST_STATE_NEXT (element);
2512 old_pending = GST_STATE_PENDING (element);
2514 /* this is the (new) state we should go to. TARGET is the last state we set on
2516 if (state != GST_STATE_TARGET (element)) {
2517 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2518 "setting target state to %s", gst_element_state_get_name (state));
2519 GST_STATE_TARGET (element) = state;
2520 /* increment state cookie so that we can track each state change. We only do
2521 * this if this is actually a new state change. */
2522 element->state_cookie++;
2524 GST_STATE_PENDING (element) = state;
2526 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2527 "current %s, old_pending %s, next %s, old return %s",
2528 gst_element_state_get_name (current),
2529 gst_element_state_get_name (old_pending),
2530 gst_element_state_get_name (next),
2531 gst_element_state_change_return_get_name (old_ret));
2533 /* if the element was busy doing a state change, we just update the
2534 * target state, it'll get to it async then. */
2535 if (old_pending != GST_STATE_VOID_PENDING) {
2536 /* upwards state change will happen ASYNC */
2537 if (old_pending <= state)
2539 /* element is going to this state already */
2540 else if (next == state)
2542 /* element was performing an ASYNC upward state change and
2543 * we request to go downward again. Start from the next pending
2545 else if (next > state
2546 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2550 next = GST_STATE_GET_NEXT (current, state);
2551 /* now we store the next state */
2552 GST_STATE_NEXT (element) = next;
2553 /* mark busy, we need to check that there is actually a state change
2554 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2555 * the default element change_state function has no way to know what the
2556 * old value was... could consider this a FIXME...*/
2557 if (current != next)
2558 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2560 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2562 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2563 "%s: setting state from %s to %s",
2564 (next != state ? "intermediate" : "final"),
2565 gst_element_state_get_name (current), gst_element_state_get_name (next));
2567 /* now signal any waiters, they will error since the cookie was incremented */
2568 GST_STATE_BROADCAST (element);
2570 GST_OBJECT_UNLOCK (element);
2572 ret = gst_element_change_state (element, transition);
2574 GST_STATE_UNLOCK (element);
2576 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2577 gst_element_state_change_return_get_name (ret));
2583 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2584 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2585 "element was busy with async state change");
2586 GST_OBJECT_UNLOCK (element);
2588 GST_STATE_UNLOCK (element);
2590 return GST_STATE_CHANGE_ASYNC;
2595 * gst_element_change_state:
2596 * @element: a #GstElement
2597 * @transition: the requested transition
2599 * Perform @transition on @element.
2601 * This function must be called with STATE_LOCK held and is mainly used
2604 * Returns: the #GstStateChangeReturn of the state transition.
2606 GstStateChangeReturn
2607 gst_element_change_state (GstElement * element, GstStateChange transition)
2609 GstElementClass *oclass;
2610 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2612 oclass = GST_ELEMENT_GET_CLASS (element);
2614 /* call the state change function so it can set the state */
2615 if (oclass->change_state)
2616 ret = (oclass->change_state) (element, transition);
2618 ret = GST_STATE_CHANGE_FAILURE;
2621 case GST_STATE_CHANGE_FAILURE:
2622 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2623 "have FAILURE change_state return");
2624 /* state change failure */
2625 gst_element_abort_state (element);
2627 case GST_STATE_CHANGE_ASYNC:
2631 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2632 "element will change state ASYNC");
2634 target = GST_STATE_TARGET (element);
2636 if (target > GST_STATE_READY)
2639 /* else we just continue the state change downwards */
2640 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2641 "forcing commit state %s <= %s",
2642 gst_element_state_get_name (target),
2643 gst_element_state_get_name (GST_STATE_READY));
2645 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2648 case GST_STATE_CHANGE_SUCCESS:
2649 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2650 "element changed state SUCCESS");
2651 /* we can commit the state now which will proceeed to
2653 ret = gst_element_continue_state (element, ret);
2655 case GST_STATE_CHANGE_NO_PREROLL:
2656 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2657 "element changed state NO_PREROLL");
2658 /* we can commit the state now which will proceeed to
2660 ret = gst_element_continue_state (element, ret);
2663 goto invalid_return;
2666 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2671 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2679 GST_OBJECT_LOCK (element);
2680 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2681 g_critical ("%s: unknown return value %d from a state change function",
2682 GST_ELEMENT_NAME (element), ret);
2684 /* we are in error now */
2685 ret = GST_STATE_CHANGE_FAILURE;
2686 GST_STATE_RETURN (element) = ret;
2687 GST_OBJECT_UNLOCK (element);
2693 /* gst_iterator_fold functions for pads_activate
2694 * Stop the iterator if activating one pad failed, but only if that pad
2695 * has not been removed from the element. */
2697 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2699 GstPad *pad = g_value_get_object (vpad);
2700 gboolean cont = TRUE;
2702 if (!gst_pad_set_active (pad, *active)) {
2703 if (GST_PAD_PARENT (pad) != NULL) {
2705 g_value_set_boolean (ret, FALSE);
2712 /* returns false on error or early cutout of the fold, true if all
2713 * pads in @iter were (de)activated successfully. */
2715 iterator_activate_fold_with_resync (GstIterator * iter,
2716 GstIteratorFoldFunction func, gpointer user_data)
2718 GstIteratorResult ires;
2721 /* no need to unset this later, it's just a boolean */
2722 g_value_init (&ret, G_TYPE_BOOLEAN);
2723 g_value_set_boolean (&ret, TRUE);
2726 ires = gst_iterator_fold (iter, func, &ret, user_data);
2728 case GST_ITERATOR_RESYNC:
2729 /* need to reset the result again */
2730 g_value_set_boolean (&ret, TRUE);
2731 gst_iterator_resync (iter);
2733 case GST_ITERATOR_DONE:
2734 /* all pads iterated, return collected value */
2737 /* iterator returned _ERROR or premature end with _OK,
2738 * mark an error and exit */
2739 g_value_set_boolean (&ret, FALSE);
2744 /* return collected value */
2745 return g_value_get_boolean (&ret);
2748 /* is called with STATE_LOCK
2750 * Pads are activated from source pads to sinkpads.
2753 gst_element_pads_activate (GstElement * element, gboolean active)
2758 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2759 "%s pads", active ? "activate" : "deactivate");
2761 iter = gst_element_iterate_src_pads (element);
2763 iterator_activate_fold_with_resync (iter,
2764 (GstIteratorFoldFunction) activate_pads, &active);
2765 gst_iterator_free (iter);
2766 if (G_UNLIKELY (!res))
2769 iter = gst_element_iterate_sink_pads (element);
2771 iterator_activate_fold_with_resync (iter,
2772 (GstIteratorFoldFunction) activate_pads, &active);
2773 gst_iterator_free (iter);
2774 if (G_UNLIKELY (!res))
2777 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2778 "pad %sactivation successful", active ? "" : "de");
2785 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2786 "pad %sactivation failed", active ? "" : "de");
2791 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2792 "sink pads_activate failed");
2797 /* is called with STATE_LOCK */
2798 static GstStateChangeReturn
2799 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2801 GstState state, next;
2802 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2804 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2806 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2807 next = GST_STATE_TRANSITION_NEXT (transition);
2809 /* if the element already is in the given state, we just return success */
2810 if (next == GST_STATE_VOID_PENDING || state == next)
2813 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2814 "default handler tries setting state from %s to %s (%04x)",
2815 gst_element_state_get_name (state),
2816 gst_element_state_get_name (next), transition);
2818 switch (transition) {
2819 case GST_STATE_CHANGE_NULL_TO_READY:
2821 case GST_STATE_CHANGE_READY_TO_PAUSED:
2822 if (!gst_element_pads_activate (element, TRUE)) {
2823 result = GST_STATE_CHANGE_FAILURE;
2826 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2828 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2830 case GST_STATE_CHANGE_PAUSED_TO_READY:
2831 case GST_STATE_CHANGE_READY_TO_NULL:{
2834 /* deactivate pads in both cases, since they are activated on
2835 ready->paused but the element might not have made it to paused */
2836 if (!gst_element_pads_activate (element, FALSE)) {
2837 result = GST_STATE_CHANGE_FAILURE;
2840 /* Remove all non-persistent contexts */
2841 GST_OBJECT_LOCK (element);
2842 for (l = element->contexts; l;) {
2843 GstContext *context = l->data;
2845 if (!gst_context_is_persistent (context)) {
2848 gst_context_unref (context);
2850 element->contexts = g_list_delete_link (element->contexts, l);
2856 GST_OBJECT_UNLOCK (element);
2860 /* this will catch real but unhandled state changes;
2861 * can only be caused by:
2862 * - a new state was added
2863 * - somehow the element was asked to jump across an intermediate state
2865 g_warning ("Unhandled state change from %s to %s",
2866 gst_element_state_get_name (state),
2867 gst_element_state_get_name (next));
2874 GST_OBJECT_LOCK (element);
2875 result = GST_STATE_RETURN (element);
2876 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2877 "element is already in the %s state",
2878 gst_element_state_get_name (state));
2879 GST_OBJECT_UNLOCK (element);
2886 * gst_element_get_factory:
2887 * @element: a #GstElement to request the element factory of.
2889 * Retrieves the factory that was used to create this element.
2891 * Returns: (transfer none): the #GstElementFactory used for creating this
2892 * element. no refcounting is needed.
2895 gst_element_get_factory (GstElement * element)
2897 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2899 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2903 gst_element_dispose (GObject * object)
2905 GstElement *element = GST_ELEMENT_CAST (object);
2908 GstElementClass *oclass;
2911 oclass = GST_ELEMENT_GET_CLASS (element);
2913 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2915 if (GST_STATE (element) != GST_STATE_NULL)
2918 /* start by releasing all request pads, this might also remove some dynamic
2920 walk = element->pads;
2922 GstPad *pad = GST_PAD_CAST (walk->data);
2926 if (oclass->release_pad && GST_PAD_PAD_TEMPLATE (pad) &&
2927 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
2928 == GST_PAD_REQUEST) {
2929 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2930 "removing request pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2931 oclass->release_pad (element, pad);
2933 /* in case the release_pad function removed the next pad too */
2934 if (walk && g_list_position (element->pads, walk) == -1)
2935 walk = element->pads;
2938 /* remove the remaining pads */
2939 while (element->pads) {
2940 GstPad *pad = GST_PAD_CAST (element->pads->data);
2941 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2942 "removing pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2943 if (!gst_element_remove_pad (element, pad)) {
2944 /* only happens when someone unparented our pad.. */
2945 g_critical ("failed to remove pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2950 GST_OBJECT_LOCK (element);
2951 clock_p = &element->clock;
2952 bus_p = &element->bus;
2953 gst_object_replace ((GstObject **) clock_p, NULL);
2954 gst_object_replace ((GstObject **) bus_p, NULL);
2955 g_list_free_full (element->contexts, (GDestroyNotify) gst_context_unref);
2956 GST_OBJECT_UNLOCK (element);
2958 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2960 G_OBJECT_CLASS (parent_class)->dispose (object);
2969 is_locked = GST_ELEMENT_IS_LOCKED_STATE (element);
2971 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2973 "You need to explicitly set elements to the NULL state before\n"
2974 "dropping the final reference, to allow them to clean up.\n"
2975 "This problem may also be caused by a refcounting bug in the\n"
2976 "application or some element.\n",
2977 GST_OBJECT_NAME (element),
2978 gst_element_state_get_name (GST_STATE (element)),
2979 is_locked ? " (locked)" : "");
2985 gst_element_finalize (GObject * object)
2987 GstElement *element = GST_ELEMENT_CAST (object);
2989 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2991 g_cond_clear (&element->state_cond);
2992 g_rec_mutex_clear (&element->state_lock);
2994 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2996 G_OBJECT_CLASS (parent_class)->finalize (object);
3000 gst_element_set_bus_func (GstElement * element, GstBus * bus)
3004 g_return_if_fail (GST_IS_ELEMENT (element));
3006 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
3008 GST_OBJECT_LOCK (element);
3009 bus_p = &GST_ELEMENT_BUS (element);
3010 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
3011 GST_OBJECT_UNLOCK (element);
3015 * gst_element_set_bus:
3016 * @element: a #GstElement to set the bus of.
3017 * @bus: (transfer none): the #GstBus to set.
3019 * Sets the bus of the element. Increases the refcount on the bus.
3020 * For internal use only, unless you're testing elements.
3025 gst_element_set_bus (GstElement * element, GstBus * bus)
3027 GstElementClass *oclass;
3029 g_return_if_fail (GST_IS_ELEMENT (element));
3031 oclass = GST_ELEMENT_GET_CLASS (element);
3033 if (oclass->set_bus)
3034 oclass->set_bus (element, bus);
3038 * gst_element_get_bus:
3039 * @element: a #GstElement to get the bus of.
3041 * Returns the bus of the element. Note that only a #GstPipeline will provide a
3042 * bus for the application.
3044 * Returns: (transfer full): the element's #GstBus. unref after usage.
3049 gst_element_get_bus (GstElement * element)
3051 GstBus *result = NULL;
3053 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3055 GST_OBJECT_LOCK (element);
3056 if ((result = GST_ELEMENT_BUS (element)))
3057 gst_object_ref (result);
3058 GST_OBJECT_UNLOCK (element);
3060 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,
3067 gst_element_set_context_default (GstElement * element, GstContext * context)
3069 const gchar *context_type;
3072 GST_OBJECT_LOCK (element);
3073 context_type = gst_context_get_context_type (context);
3074 for (l = element->contexts; l; l = l->next) {
3075 GstContext *tmp = l->data;
3076 const gchar *tmp_type = gst_context_get_context_type (tmp);
3078 /* Always store newest context but never replace
3079 * a persistent one by a non-persistent one */
3080 if (strcmp (context_type, tmp_type) == 0 &&
3081 (gst_context_is_persistent (context) ||
3082 !gst_context_is_persistent (tmp))) {
3083 gst_context_replace ((GstContext **) & l->data, context);
3087 /* Not found? Add */
3090 g_list_prepend (element->contexts, gst_context_ref (context));
3092 GST_OBJECT_UNLOCK (element);
3096 * gst_element_set_context:
3097 * @element: a #GstElement to set the context of.
3098 * @context: (transfer none): the #GstContext to set.
3100 * Sets the context of the element. Increases the refcount of the context.
3105 gst_element_set_context (GstElement * element, GstContext * context)
3107 GstElementClass *oclass;
3109 g_return_if_fail (GST_IS_ELEMENT (element));
3111 oclass = GST_ELEMENT_GET_CLASS (element);
3113 GST_CAT_DEBUG_OBJECT (GST_CAT_CONTEXT, element,
3114 "set context %p %" GST_PTR_FORMAT, context,
3115 gst_context_get_structure (context));
3117 if (oclass->set_context)
3118 oclass->set_context (element, context);
3122 * gst_element_get_contexts:
3123 * @element: a #GstElement to set the context of.
3125 * Gets the contexts set on the element.
3129 * Returns: (element-type Gst.Context) (transfer full): List of #GstContext
3134 gst_element_get_contexts (GstElement * element)
3138 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
3140 GST_OBJECT_LOCK (element);
3141 ret = g_list_copy_deep (element->contexts, (GCopyFunc) gst_context_ref, NULL);
3142 GST_OBJECT_UNLOCK (element);
3148 _match_context_type (GstContext * c1, const gchar * context_type)
3150 const gchar *c1_type;
3152 c1_type = gst_context_get_context_type (c1);
3154 return g_strcmp0 (c1_type, context_type);
3158 * gst_element_get_context_unlocked:
3159 * @element: a #GstElement to get the context of.
3160 * @context_type: a name of a context to retrieve
3162 * Gets the context with @context_type set on the element or NULL.
3164 * Returns: (transfer full): A #GstContext or NULL
3169 gst_element_get_context_unlocked (GstElement * element,
3170 const gchar * context_type)
3172 GstContext *ret = NULL;
3175 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
3178 g_list_find_custom (element->contexts, context_type,
3179 (GCompareFunc) _match_context_type);
3180 if (node && node->data)
3181 ret = gst_context_ref (node->data);
3187 * gst_element_get_context:
3188 * @element: a #GstElement to get the context of.
3189 * @context_type: a name of a context to retrieve
3191 * Gets the context with @context_type set on the element or NULL.
3195 * Returns: (transfer full): A #GstContext or NULL
3200 gst_element_get_context (GstElement * element, const gchar * context_type)
3202 GstContext *ret = NULL;
3204 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
3206 GST_OBJECT_LOCK (element);
3207 ret = gst_element_get_context_unlocked (element, context_type);
3208 GST_OBJECT_UNLOCK (element);