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 #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_func (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_func);
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_get_request_pad().
314 * This does not unref the pad. If the pad was created by using
315 * gst_element_get_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): the GstClock provided by the element or %NULL
350 * 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 * Returns: (transfer full): the #GstClock of the element. unref after usage.
429 gst_element_get_clock (GstElement * element)
433 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
435 GST_OBJECT_LOCK (element);
436 if ((result = element->clock))
437 gst_object_ref (result);
438 GST_OBJECT_UNLOCK (element);
444 * gst_element_set_base_time:
445 * @element: a #GstElement.
446 * @time: the base time to set.
448 * Set the base time of an element. See gst_element_get_base_time().
453 gst_element_set_base_time (GstElement * element, GstClockTime time)
457 g_return_if_fail (GST_IS_ELEMENT (element));
459 GST_OBJECT_LOCK (element);
460 old = element->base_time;
461 element->base_time = time;
462 GST_OBJECT_UNLOCK (element);
464 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
465 "set base_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
466 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
470 * gst_element_get_base_time:
471 * @element: a #GstElement.
473 * Returns the base time of the element. The base time is the
474 * absolute time of the clock when this element was last put to
475 * PLAYING. Subtracting the base time from the clock time gives
476 * the running time of the element.
478 * Returns: the base time of the element.
483 gst_element_get_base_time (GstElement * element)
487 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
489 GST_OBJECT_LOCK (element);
490 result = element->base_time;
491 GST_OBJECT_UNLOCK (element);
497 * gst_element_set_start_time:
498 * @element: a #GstElement.
499 * @time: the base time to set.
501 * Set the start time of an element. The start time of the element is the
502 * running time of the element when it last went to the PAUSED state. In READY
503 * or after a flushing seek, it is set to 0.
505 * Toplevel elements like #GstPipeline will manage the start_time and
506 * base_time on its children. Setting the start_time to #GST_CLOCK_TIME_NONE
507 * on such a toplevel element will disable the distribution of the base_time to
508 * the children and can be useful if the application manages the base_time
509 * itself, for example if you want to synchronize capture from multiple
510 * pipelines, and you can also ensure that the pipelines have the same clock.
515 gst_element_set_start_time (GstElement * element, GstClockTime time)
519 g_return_if_fail (GST_IS_ELEMENT (element));
521 GST_OBJECT_LOCK (element);
522 old = GST_ELEMENT_START_TIME (element);
523 GST_ELEMENT_START_TIME (element) = time;
524 GST_OBJECT_UNLOCK (element);
526 GST_CAT_DEBUG_OBJECT (GST_CAT_CLOCK, element,
527 "set start_time=%" GST_TIME_FORMAT ", old %" GST_TIME_FORMAT,
528 GST_TIME_ARGS (time), GST_TIME_ARGS (old));
532 * gst_element_get_start_time:
533 * @element: a #GstElement.
535 * Returns the start time of the element. The start time is the
536 * running time of the clock when this element was last put to PAUSED.
538 * Usually the start_time is managed by a toplevel element such as
543 * Returns: the start time of the element.
546 gst_element_get_start_time (GstElement * element)
550 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_CLOCK_TIME_NONE);
552 GST_OBJECT_LOCK (element);
553 result = GST_ELEMENT_START_TIME (element);
554 GST_OBJECT_UNLOCK (element);
561 * gst_element_set_index:
562 * @element: a #GstElement.
563 * @index: (transfer none): a #GstIndex.
565 * Set @index on the element. The refcount of the index
566 * will be increased, any previously set index is unreffed.
571 gst_element_set_index (GstElement * element, GstIndex * index)
573 GstElementClass *oclass;
575 g_return_if_fail (GST_IS_ELEMENT (element));
576 g_return_if_fail (index == NULL || GST_IS_INDEX (index));
578 oclass = GST_ELEMENT_GET_CLASS (element);
580 if (oclass->set_index)
581 oclass->set_index (element, index);
585 * gst_element_get_index:
586 * @element: a #GstElement.
588 * Gets the index from the element.
590 * Returns: (transfer full): a #GstIndex or %NULL when no index was set on the
591 * element. unref after usage.
596 gst_element_get_index (GstElement * element)
598 GstElementClass *oclass;
599 GstIndex *result = NULL;
601 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
603 oclass = GST_ELEMENT_GET_CLASS (element);
605 if (oclass->get_index)
606 result = oclass->get_index (element);
613 * gst_element_add_pad:
614 * @element: a #GstElement to add the pad to.
615 * @pad: (transfer full): the #GstPad to add to the element.
617 * Adds a pad (link point) to @element. @pad's parent will be set to @element;
618 * see gst_object_set_parent() for refcounting information.
620 * Pads are not automatically activated so elements should perform the needed
621 * steps to activate the pad in case this pad is added in the PAUSED or PLAYING
622 * state. See gst_pad_set_active() for more information about activating pads.
624 * The pad and the element should be unlocked when calling this function.
626 * This function will emit the #GstElement::pad-added signal on the element.
628 * Returns: %TRUE if the pad could be added. This function can fail when
629 * a pad with the same name already existed or the pad already had another
635 gst_element_add_pad (GstElement * element, GstPad * pad)
640 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
641 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
643 /* locking pad to look at the name */
644 GST_OBJECT_LOCK (pad);
645 pad_name = g_strdup (GST_PAD_NAME (pad));
646 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "adding pad '%s'",
647 GST_STR_NULL (pad_name));
648 flushing = GST_PAD_IS_FLUSHING (pad);
649 GST_OBJECT_FLAG_SET (pad, GST_PAD_FLAG_NEED_PARENT);
650 GST_OBJECT_UNLOCK (pad);
652 /* then check to see if there's already a pad by that name here */
653 GST_OBJECT_LOCK (element);
654 if (G_UNLIKELY (!gst_object_check_uniqueness (element->pads, pad_name)))
657 /* try to set the pad's parent */
658 if (G_UNLIKELY (!gst_object_set_parent (GST_OBJECT_CAST (pad),
659 GST_OBJECT_CAST (element))))
662 /* check for flushing pads */
663 if (flushing && (GST_STATE (element) > GST_STATE_READY ||
664 GST_STATE_NEXT (element) == GST_STATE_PAUSED)) {
665 g_warning ("adding flushing pad '%s' to running element '%s', you need to "
666 "use gst_pad_set_active(pad,TRUE) before adding it.",
667 GST_STR_NULL (pad_name), GST_ELEMENT_NAME (element));
669 GST_OBJECT_LOCK (pad);
670 GST_PAD_UNSET_FLUSHING (pad);
671 GST_OBJECT_UNLOCK (pad);
676 /* add it to the list */
677 switch (gst_pad_get_direction (pad)) {
679 element->srcpads = g_list_append (element->srcpads, pad);
680 element->numsrcpads++;
683 element->sinkpads = g_list_append (element->sinkpads, pad);
684 element->numsinkpads++;
689 element->pads = g_list_append (element->pads, pad);
691 element->pads_cookie++;
692 GST_OBJECT_UNLOCK (element);
694 /* emit the PAD_ADDED signal */
695 g_signal_emit (element, gst_element_signals[PAD_ADDED], 0, pad);
702 g_critical ("Padname %s is not unique in element %s, not adding",
703 pad_name, GST_ELEMENT_NAME (element));
704 GST_OBJECT_UNLOCK (element);
711 ("Pad %s already has parent when trying to add to element %s",
712 pad_name, GST_ELEMENT_NAME (element));
713 GST_OBJECT_UNLOCK (element);
719 GST_OBJECT_LOCK (pad);
721 ("Trying to add pad %s to element %s, but it has no direction",
722 GST_OBJECT_NAME (pad), GST_ELEMENT_NAME (element));
723 GST_OBJECT_UNLOCK (pad);
724 GST_OBJECT_UNLOCK (element);
730 * gst_element_remove_pad:
731 * @element: a #GstElement to remove pad from.
732 * @pad: (transfer full): the #GstPad to remove from the element.
734 * Removes @pad from @element. @pad will be destroyed if it has not been
735 * referenced elsewhere using gst_object_unparent().
737 * This function is used by plugin developers and should not be used
738 * by applications. Pads that were dynamically requested from elements
739 * with gst_element_get_request_pad() should be released with the
740 * gst_element_release_request_pad() function instead.
742 * Pads are not automatically deactivated so elements should perform the needed
743 * steps to deactivate the pad in case this pad is removed in the PAUSED or
744 * PLAYING state. See gst_pad_set_active() for more information about
747 * The pad and the element should be unlocked when calling this function.
749 * This function will emit the #GstElement::pad-removed signal on the element.
751 * Returns: %TRUE if the pad could be removed. Can return %FALSE if the
752 * pad does not belong to the provided element.
757 gst_element_remove_pad (GstElement * element, GstPad * pad)
761 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
762 g_return_val_if_fail (GST_IS_PAD (pad), FALSE);
764 /* locking pad to look at the name and parent */
765 GST_OBJECT_LOCK (pad);
766 GST_CAT_INFO_OBJECT (GST_CAT_ELEMENT_PADS, element, "removing pad '%s'",
767 GST_STR_NULL (GST_PAD_NAME (pad)));
769 if (G_UNLIKELY (GST_PAD_PARENT (pad) != element))
771 GST_OBJECT_UNLOCK (pad);
774 if ((peer = gst_pad_get_peer (pad))) {
775 /* window for MT unsafeness, someone else could unlink here
776 * and then we call unlink with wrong pads. The unlink
777 * function would catch this and safely return failed. */
778 if (GST_PAD_IS_SRC (pad))
779 gst_pad_unlink (pad, peer);
781 gst_pad_unlink (peer, pad);
783 gst_object_unref (peer);
786 GST_OBJECT_LOCK (element);
787 /* remove it from the list */
788 switch (gst_pad_get_direction (pad)) {
790 element->srcpads = g_list_remove (element->srcpads, pad);
791 element->numsrcpads--;
794 element->sinkpads = g_list_remove (element->sinkpads, pad);
795 element->numsinkpads--;
798 g_critical ("Removing pad without direction???");
801 element->pads = g_list_remove (element->pads, pad);
803 element->pads_cookie++;
804 GST_OBJECT_UNLOCK (element);
806 /* emit the PAD_REMOVED signal before unparenting and losing the last ref. */
807 g_signal_emit (element, gst_element_signals[PAD_REMOVED], 0, pad);
809 gst_object_unparent (GST_OBJECT_CAST (pad));
816 /* locking order is element > pad */
817 GST_OBJECT_UNLOCK (pad);
819 GST_OBJECT_LOCK (element);
820 GST_OBJECT_LOCK (pad);
821 g_critical ("Padname %s:%s does not belong to element %s when removing",
822 GST_DEBUG_PAD_NAME (pad), GST_ELEMENT_NAME (element));
823 GST_OBJECT_UNLOCK (pad);
824 GST_OBJECT_UNLOCK (element);
830 * gst_element_no_more_pads:
831 * @element: a #GstElement
833 * Use this function to signal that the element does not expect any more pads
834 * to show up in the current pipeline. This function should be called whenever
835 * pads have been added by the element itself. Elements with #GST_PAD_SOMETIMES
836 * pad templates use this in combination with autopluggers to figure out that
837 * the element is done initializing its pads.
839 * This function emits the #GstElement::no-more-pads signal.
844 gst_element_no_more_pads (GstElement * element)
846 g_return_if_fail (GST_IS_ELEMENT (element));
848 g_signal_emit (element, gst_element_signals[NO_MORE_PADS], 0);
852 pad_compare_name (GstPad * pad1, const gchar * name)
856 GST_OBJECT_LOCK (pad1);
857 result = strcmp (GST_PAD_NAME (pad1), name);
858 GST_OBJECT_UNLOCK (pad1);
864 * gst_element_get_static_pad:
865 * @element: a #GstElement to find a static pad of.
866 * @name: the name of the static #GstPad to retrieve.
868 * Retrieves a pad from @element by name. This version only retrieves
869 * already-existing (i.e. 'static') pads.
871 * Returns: (transfer full): the requested #GstPad if found, otherwise %NULL.
877 gst_element_get_static_pad (GstElement * element, const gchar * name)
880 GstPad *result = NULL;
882 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
883 g_return_val_if_fail (name != NULL, NULL);
885 GST_OBJECT_LOCK (element);
887 g_list_find_custom (element->pads, name, (GCompareFunc) pad_compare_name);
889 result = GST_PAD_CAST (find->data);
890 gst_object_ref (result);
893 if (result == NULL) {
894 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "no such pad '%s' in element \"%s\"",
895 name, GST_ELEMENT_NAME (element));
897 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
898 GST_ELEMENT_NAME (element), name);
900 GST_OBJECT_UNLOCK (element);
906 _gst_element_request_pad (GstElement * element, GstPadTemplate * templ,
907 const gchar * name, const GstCaps * caps)
909 GstPad *newpad = NULL;
910 GstElementClass *oclass;
912 oclass = GST_ELEMENT_GET_CLASS (element);
914 #ifndef G_DISABLE_CHECKS
915 /* Some sanity checking here */
919 /* Is this the template name? */
920 if (strstr (name, "%") || !strchr (templ->name_template, '%')) {
921 g_return_val_if_fail (strcmp (name, templ->name_template) == 0, NULL);
923 const gchar *str, *data;
926 /* Otherwise check if it's a valid name for the name template */
927 str = strchr (templ->name_template, '%');
928 g_return_val_if_fail (str != NULL, NULL);
929 g_return_val_if_fail (strncmp (templ->name_template, name,
930 str - templ->name_template) == 0, NULL);
931 g_return_val_if_fail (strlen (name) > str - templ->name_template, NULL);
933 data = name + (str - templ->name_template);
935 /* Can either be %s or %d or %u, do sanity checking for %d */
936 if (*(str + 1) == 'd') {
940 tmp = g_ascii_strtoll (data, &endptr, 10);
941 g_return_val_if_fail (tmp >= G_MININT && tmp <= G_MAXINT
942 && *endptr == '\0', NULL);
943 } else if (*(str + 1) == 'u') {
947 tmp = g_ascii_strtoull (data, &endptr, 10);
948 g_return_val_if_fail (tmp <= G_MAXUINT && *endptr == '\0', NULL);
952 pad = gst_element_get_static_pad (element, name);
954 gst_object_unref (pad);
955 /* FIXME 0.11: Change this to g_return_val_if_fail() */
956 g_critical ("Element %s already has a pad named %s, the behaviour of "
957 " gst_element_get_request_pad() for existing pads is undefined!",
958 GST_ELEMENT_NAME (element), name);
963 if (oclass->request_new_pad)
964 newpad = (oclass->request_new_pad) (element, templ, name, caps);
967 gst_object_ref (newpad);
973 * gst_element_get_request_pad:
974 * @element: a #GstElement to find a request pad of.
975 * @name: the name of the request #GstPad to retrieve.
977 * Retrieves a pad from the element by name (e.g. "src_\%d"). This version only
978 * retrieves request pads. The pad should be released with
979 * gst_element_release_request_pad().
981 * This method is slow and will be deprecated in the future. New code should
982 * use gst_element_request_pad() with the requested template.
984 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
985 * Release after usage.
988 gst_element_get_request_pad (GstElement * element, const gchar * name)
990 GstPadTemplate *templ = NULL;
992 const gchar *req_name = NULL;
993 gboolean templ_found = FALSE;
996 gchar *str, *endptr = NULL;
997 GstElementClass *class;
999 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1000 g_return_val_if_fail (name != NULL, NULL);
1002 class = GST_ELEMENT_GET_CLASS (element);
1004 /* if the name contains a %, we assume it's the complete template name. Get
1005 * the template and try to get a pad */
1006 if (strstr (name, "%")) {
1007 templ = gst_element_class_get_request_pad_template (class, name);
1012 /* there is no % in the name, try to find a matching template */
1013 list = class->padtemplates;
1014 while (!templ_found && list) {
1015 templ = (GstPadTemplate *) list->data;
1016 if (templ->presence == GST_PAD_REQUEST) {
1017 GST_CAT_DEBUG (GST_CAT_PADS, "comparing %s to %s", name,
1018 templ->name_template);
1019 /* see if we find an exact match */
1020 if (strcmp (name, templ->name_template) == 0) {
1025 /* Because of sanity checks in gst_pad_template_new(), we know that %s
1026 and %d and %u, occurring at the end of the name_template, are the only
1028 else if ((str = strchr (templ->name_template, '%'))
1029 && strncmp (templ->name_template, name,
1030 str - templ->name_template) == 0
1031 && strlen (name) > str - templ->name_template) {
1032 data = name + (str - templ->name_template);
1033 if (*(str + 1) == 'd') {
1037 tmp = strtol (data, &endptr, 10);
1038 if (tmp != G_MINLONG && tmp != G_MAXLONG && endptr &&
1044 } else if (*(str + 1) == 'u') {
1048 tmp = strtoul (data, &endptr, 10);
1049 if (tmp != G_MAXULONG && endptr && *endptr == '\0') {
1069 pad = _gst_element_request_pad (element, templ, req_name, NULL);
1075 * gst_element_request_pad:
1076 * @element: a #GstElement to find a request pad of.
1077 * @templ: a #GstPadTemplate of which we want a pad of.
1078 * @name: (transfer none) (allow-none): the name of the request #GstPad
1079 * to retrieve. Can be %NULL.
1080 * @caps: (transfer none) (allow-none): the caps of the pad we want to
1081 * request. Can be %NULL.
1083 * Retrieves a request pad from the element according to the provided template.
1084 * Pad templates can be looked up using
1085 * gst_element_factory_get_static_pad_templates().
1087 * The pad should be released with gst_element_release_request_pad().
1089 * Returns: (transfer full): requested #GstPad if found, otherwise %NULL.
1090 * Release after usage.
1093 gst_element_request_pad (GstElement * element,
1094 GstPadTemplate * templ, const gchar * name, const GstCaps * caps)
1096 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1097 g_return_val_if_fail (templ != NULL, NULL);
1098 g_return_val_if_fail (templ->presence == GST_PAD_REQUEST, NULL);
1100 return _gst_element_request_pad (element, templ, name, caps);
1103 static GstIterator *
1104 gst_element_iterate_pad_list (GstElement * element, GList ** padlist)
1106 GstIterator *result;
1108 GST_OBJECT_LOCK (element);
1109 result = gst_iterator_new_list (GST_TYPE_PAD,
1110 GST_OBJECT_GET_LOCK (element),
1111 &element->pads_cookie, padlist, (GObject *) element, NULL);
1112 GST_OBJECT_UNLOCK (element);
1118 * gst_element_iterate_pads:
1119 * @element: a #GstElement to iterate pads of.
1121 * Retrieves an iterator of @element's pads. The iterator should
1122 * be freed after usage. Also more specialized iterators exists such as
1123 * gst_element_iterate_src_pads() or gst_element_iterate_sink_pads().
1125 * The order of pads returned by the iterator will be the order in which
1126 * the pads were added to the element.
1128 * Returns: (transfer full): the #GstIterator of #GstPad.
1133 gst_element_iterate_pads (GstElement * element)
1135 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1137 return gst_element_iterate_pad_list (element, &element->pads);
1141 * gst_element_iterate_src_pads:
1142 * @element: a #GstElement.
1144 * Retrieves an iterator of @element's source pads.
1146 * The order of pads returned by the iterator will be the order in which
1147 * the pads were added to the element.
1149 * Returns: (transfer full): the #GstIterator of #GstPad.
1154 gst_element_iterate_src_pads (GstElement * element)
1156 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1158 return gst_element_iterate_pad_list (element, &element->srcpads);
1162 * gst_element_iterate_sink_pads:
1163 * @element: a #GstElement.
1165 * Retrieves an iterator of @element's sink pads.
1167 * The order of pads returned by the iterator will be the order in which
1168 * the pads were added to the element.
1170 * Returns: (transfer full): the #GstIterator of #GstPad.
1175 gst_element_iterate_sink_pads (GstElement * element)
1177 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
1179 return gst_element_iterate_pad_list (element, &element->sinkpads);
1183 * gst_element_class_add_pad_template:
1184 * @klass: the #GstElementClass to add the pad template to.
1185 * @templ: (transfer full): a #GstPadTemplate to add to the element class.
1187 * Adds a padtemplate to an element class. This is mainly used in the _class_init
1188 * functions of classes. If a pad template with the same name as an already
1189 * existing one is added the old one is replaced by the new one.
1193 gst_element_class_add_pad_template (GstElementClass * klass,
1194 GstPadTemplate * templ)
1196 GList *template_list = klass->padtemplates;
1198 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1199 g_return_if_fail (GST_IS_PAD_TEMPLATE (templ));
1201 /* If we already have a pad template with the same name replace the
1203 while (template_list) {
1204 GstPadTemplate *padtempl = (GstPadTemplate *) template_list->data;
1206 /* Found pad with the same name, replace and return */
1207 if (strcmp (templ->name_template, padtempl->name_template) == 0) {
1208 gst_object_unref (padtempl);
1209 template_list->data = templ;
1212 template_list = g_list_next (template_list);
1215 /* Take ownership of the floating ref */
1216 gst_object_ref_sink (templ);
1218 klass->padtemplates = g_list_append (klass->padtemplates, templ);
1219 klass->numpadtemplates++;
1223 * gst_element_class_add_metadata:
1224 * @klass: class to set metadata for
1225 * @key: the key to set
1226 * @value: the value to set
1228 * Set @key with @value as metadata in @klass.
1231 gst_element_class_add_metadata (GstElementClass * klass,
1232 const gchar * key, const gchar * value)
1234 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1235 g_return_if_fail (key != NULL);
1236 g_return_if_fail (value != NULL);
1238 gst_structure_set ((GstStructure *) klass->metadata,
1239 key, G_TYPE_STRING, value, NULL);
1243 * gst_element_class_add_static_metadata:
1244 * @klass: class to set metadata for
1245 * @key: the key to set
1246 * @value: the value to set
1248 * Set @key with @value as metadata in @klass.
1250 * Same as gst_element_class_add_metadata(), but @value must be a static string
1251 * or an inlined string, as it will not be copied. (GStreamer plugins will
1252 * be made resident once loaded, so this function can be used even from
1253 * dynamically loaded plugins.)
1256 gst_element_class_add_static_metadata (GstElementClass * klass,
1257 const gchar * key, const gchar * value)
1259 GValue val = G_VALUE_INIT;
1261 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1262 g_return_if_fail (key != NULL);
1263 g_return_if_fail (value != NULL);
1265 g_value_init (&val, G_TYPE_STRING);
1266 g_value_set_static_string (&val, value);
1267 gst_structure_take_value ((GstStructure *) klass->metadata, key, &val);
1271 * gst_element_class_set_metadata:
1272 * @klass: class to set metadata for
1273 * @longname: The long English name of the element. E.g. "File Sink"
1274 * @classification: String describing the type of element, as an unordered list
1275 * separated with slashes ('/'). See draft-klass.txt of the design docs
1276 * for more details and common types. E.g: "Sink/File"
1277 * @description: Sentence describing the purpose of the element.
1278 * E.g: "Write stream to a file"
1279 * @author: Name and contact details of the author(s). Use \n to separate
1280 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1282 * Sets the detailed information for a #GstElementClass.
1283 * <note>This function is for use in _class_init functions only.</note>
1286 gst_element_class_set_metadata (GstElementClass * klass,
1287 const gchar * longname, const gchar * classification,
1288 const gchar * description, const gchar * author)
1290 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1291 g_return_if_fail (longname != NULL && *longname != '\0');
1292 g_return_if_fail (classification != NULL && *classification != '\0');
1293 g_return_if_fail (description != NULL && *description != '\0');
1294 g_return_if_fail (author != NULL && *author != '\0');
1296 gst_structure_id_set ((GstStructure *) klass->metadata,
1297 GST_QUARK (ELEMENT_METADATA_LONGNAME), G_TYPE_STRING, longname,
1298 GST_QUARK (ELEMENT_METADATA_KLASS), G_TYPE_STRING, classification,
1299 GST_QUARK (ELEMENT_METADATA_DESCRIPTION), G_TYPE_STRING, description,
1300 GST_QUARK (ELEMENT_METADATA_AUTHOR), G_TYPE_STRING, author, NULL);
1304 * gst_element_class_set_static_metadata:
1305 * @klass: class to set metadata for
1306 * @longname: The long English name of the element. E.g. "File Sink"
1307 * @classification: String describing the type of element, as an unordered list
1308 * separated with slashes ('/'). See draft-klass.txt of the design docs
1309 * for more details and common types. E.g: "Sink/File"
1310 * @description: Sentence describing the purpose of the element.
1311 * E.g: "Write stream to a file"
1312 * @author: Name and contact details of the author(s). Use \n to separate
1313 * multiple author metadata. E.g: "Joe Bloggs <joe.blogs at foo.com>"
1315 * Sets the detailed information for a #GstElementClass.
1316 * <note>This function is for use in _class_init functions only.</note>
1318 * Same as gst_element_class_set_metadata(), but @longname, @classification,
1319 * @description, and @author must be static strings or inlined strings, as
1320 * they will not be copied. (GStreamer plugins will be made resident once
1321 * loaded, so this function can be used even from dynamically loaded plugins.)
1324 gst_element_class_set_static_metadata (GstElementClass * klass,
1325 const gchar * longname, const gchar * classification,
1326 const gchar * description, const gchar * author)
1328 GstStructure *s = (GstStructure *) klass->metadata;
1329 GValue val = G_VALUE_INIT;
1331 g_return_if_fail (GST_IS_ELEMENT_CLASS (klass));
1332 g_return_if_fail (longname != NULL && *longname != '\0');
1333 g_return_if_fail (classification != NULL && *classification != '\0');
1334 g_return_if_fail (description != NULL && *description != '\0');
1335 g_return_if_fail (author != NULL && *author != '\0');
1337 g_value_init (&val, G_TYPE_STRING);
1339 g_value_set_static_string (&val, longname);
1340 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_LONGNAME), &val);
1342 g_value_set_static_string (&val, classification);
1343 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_KLASS), &val);
1345 g_value_set_static_string (&val, description);
1346 gst_structure_id_set_value (s, GST_QUARK (ELEMENT_METADATA_DESCRIPTION),
1349 g_value_set_static_string (&val, author);
1350 gst_structure_id_take_value (s, GST_QUARK (ELEMENT_METADATA_AUTHOR), &val);
1354 * gst_element_class_get_metadata:
1355 * @klass: class to get metadata for
1356 * @key: the key to get
1358 * Get metadata with @key in @klass.
1360 * Returns: the metadata for @key.
1363 gst_element_class_get_metadata (GstElementClass * klass, const gchar * key)
1365 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (klass), NULL);
1366 g_return_val_if_fail (key != NULL, NULL);
1368 return gst_structure_get_string ((GstStructure *) klass->metadata, key);
1372 * gst_element_class_get_pad_template_list:
1373 * @element_class: a #GstElementClass to get pad templates of.
1375 * Retrieves a list of the pad templates associated with @element_class. The
1376 * list must not be modified by the calling code.
1377 * <note>If you use this function in the #GInstanceInitFunc of an object class
1378 * that has subclasses, make sure to pass the g_class parameter of the
1379 * #GInstanceInitFunc here.</note>
1381 * Returns: (transfer none) (element-type Gst.PadTemplate): the #GList of
1385 gst_element_class_get_pad_template_list (GstElementClass * element_class)
1387 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1389 return element_class->padtemplates;
1393 * gst_element_class_get_pad_template:
1394 * @element_class: a #GstElementClass to get the pad template of.
1395 * @name: the name of the #GstPadTemplate to get.
1397 * Retrieves a padtemplate from @element_class with the given name.
1398 * <note>If you use this function in the #GInstanceInitFunc of an object class
1399 * that has subclasses, make sure to pass the g_class parameter of the
1400 * #GInstanceInitFunc here.</note>
1402 * Returns: (transfer none): the #GstPadTemplate with the given name, or %NULL
1403 * if none was found. No unreferencing is necessary.
1406 gst_element_class_get_pad_template (GstElementClass *
1407 element_class, const gchar * name)
1411 g_return_val_if_fail (GST_IS_ELEMENT_CLASS (element_class), NULL);
1412 g_return_val_if_fail (name != NULL, NULL);
1414 padlist = element_class->padtemplates;
1417 GstPadTemplate *padtempl = (GstPadTemplate *) padlist->data;
1419 if (strcmp (padtempl->name_template, name) == 0)
1422 padlist = g_list_next (padlist);
1428 static GstPadTemplate *
1429 gst_element_class_get_request_pad_template (GstElementClass *
1430 element_class, const gchar * name)
1432 GstPadTemplate *tmpl;
1434 tmpl = gst_element_class_get_pad_template (element_class, name);
1435 if (tmpl != NULL && tmpl->presence == GST_PAD_REQUEST)
1441 /* get a random pad on element of the given direction.
1442 * The pad is random in a sense that it is the first pad that is (optionaly) linked.
1445 gst_element_get_random_pad (GstElement * element,
1446 gboolean need_linked, GstPadDirection dir)
1448 GstPad *result = NULL;
1451 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "getting a random pad");
1455 GST_OBJECT_LOCK (element);
1456 pads = element->srcpads;
1459 GST_OBJECT_LOCK (element);
1460 pads = element->sinkpads;
1463 goto wrong_direction;
1465 for (; pads; pads = g_list_next (pads)) {
1466 GstPad *pad = GST_PAD_CAST (pads->data);
1468 GST_OBJECT_LOCK (pad);
1469 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "checking pad %s:%s",
1470 GST_DEBUG_PAD_NAME (pad));
1472 if (need_linked && !GST_PAD_IS_LINKED (pad)) {
1473 /* if we require a linked pad, and it is not linked, continue the
1475 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "pad %s:%s is not linked",
1476 GST_DEBUG_PAD_NAME (pad));
1477 GST_OBJECT_UNLOCK (pad);
1480 /* found a pad, stop search */
1481 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "found pad %s:%s",
1482 GST_DEBUG_PAD_NAME (pad));
1483 GST_OBJECT_UNLOCK (pad);
1489 gst_object_ref (result);
1491 GST_OBJECT_UNLOCK (element);
1495 /* ERROR handling */
1498 g_warning ("unknown pad direction %d", dir);
1504 gst_element_default_send_event (GstElement * element, GstEvent * event)
1506 gboolean result = FALSE;
1509 pad = GST_EVENT_IS_DOWNSTREAM (event) ?
1510 gst_element_get_random_pad (element, TRUE, GST_PAD_SRC) :
1511 gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1514 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS,
1515 "pushing %s event to random %s pad %s:%s",
1516 GST_EVENT_TYPE_NAME (event),
1517 (GST_PAD_DIRECTION (pad) == GST_PAD_SRC ? "src" : "sink"),
1518 GST_DEBUG_PAD_NAME (pad));
1520 result = gst_pad_push_event (pad, event);
1521 gst_object_unref (pad);
1523 GST_CAT_INFO (GST_CAT_ELEMENT_PADS, "can't send %s event on element %s",
1524 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1525 gst_event_unref (event);
1531 * gst_element_send_event:
1532 * @element: a #GstElement to send the event to.
1533 * @event: (transfer full): the #GstEvent to send to the element.
1535 * Sends an event to an element. If the element doesn't implement an
1536 * event handler, the event will be pushed on a random linked sink pad for
1537 * upstream events or a random linked source pad for downstream events.
1539 * This function takes owership of the provided event so you should
1540 * gst_event_ref() it if you want to reuse the event after this call.
1544 * Returns: %TRUE if the event was handled. Events that trigger a preroll (such
1545 * as flushing seeks and steps) will emit %GST_MESSAGE_ASYNC_DONE.
1548 gst_element_send_event (GstElement * element, GstEvent * event)
1550 GstElementClass *oclass;
1551 gboolean result = FALSE;
1553 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1554 g_return_val_if_fail (event != NULL, FALSE);
1556 oclass = GST_ELEMENT_GET_CLASS (element);
1558 GST_STATE_LOCK (element);
1559 if (oclass->send_event) {
1560 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send %s event on element %s",
1561 GST_EVENT_TYPE_NAME (event), GST_ELEMENT_NAME (element));
1562 result = oclass->send_event (element, event);
1564 GST_STATE_UNLOCK (element);
1571 * @element: a #GstElement to send the event to.
1572 * @rate: The new playback rate
1573 * @format: The format of the seek values
1574 * @flags: The optional seek flags.
1575 * @start_type: The type and flags for the new start position
1576 * @start: The value of the new start position
1577 * @stop_type: The type and flags for the new stop position
1578 * @stop: The value of the new stop position
1580 * Sends a seek event to an element. See gst_event_new_seek() for the details of
1581 * the parameters. The seek event is sent to the element using
1582 * gst_element_send_event().
1586 * Returns: %TRUE if the event was handled. Flushing seeks will trigger a
1587 * preroll, which will emit %GST_MESSAGE_ASYNC_DONE.
1590 gst_element_seek (GstElement * element, gdouble rate, GstFormat format,
1591 GstSeekFlags flags, GstSeekType start_type, gint64 start,
1592 GstSeekType stop_type, gint64 stop)
1597 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1600 gst_event_new_seek (rate, format, flags, start_type, start, stop_type,
1602 result = gst_element_send_event (element, event);
1608 gst_element_default_query (GstElement * element, GstQuery * query)
1610 gboolean result = FALSE;
1613 pad = gst_element_get_random_pad (element, FALSE, GST_PAD_SRC);
1615 result = gst_pad_query (pad, query);
1617 gst_object_unref (pad);
1619 pad = gst_element_get_random_pad (element, TRUE, GST_PAD_SINK);
1621 GstPad *peer = gst_pad_get_peer (pad);
1624 result = gst_pad_query (peer, query);
1626 gst_object_unref (peer);
1628 gst_object_unref (pad);
1635 * gst_element_query:
1636 * @element: a #GstElement to perform the query on.
1637 * @query: (transfer none): the #GstQuery.
1639 * Performs a query on the given element.
1641 * For elements that don't implement a query handler, this function
1642 * forwards the query to a random srcpad or to the peer of a
1643 * random linked sinkpad of this element.
1645 * Please note that some queries might need a running pipeline to work.
1647 * Returns: TRUE if the query could be performed.
1652 gst_element_query (GstElement * element, GstQuery * query)
1654 GstElementClass *klass;
1656 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1657 g_return_val_if_fail (query != NULL, FALSE);
1659 klass = GST_ELEMENT_GET_CLASS (element);
1661 GST_CAT_DEBUG (GST_CAT_ELEMENT_PADS, "send query on element %s",
1662 GST_ELEMENT_NAME (element));
1663 return klass->query (element, query);
1670 gst_element_post_message_default (GstElement * element, GstMessage * message)
1673 gboolean result = FALSE;
1675 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1676 g_return_val_if_fail (message != NULL, FALSE);
1678 GST_OBJECT_LOCK (element);
1681 if (G_UNLIKELY (bus == NULL))
1684 gst_object_ref (bus);
1685 GST_OBJECT_UNLOCK (element);
1687 /* we release the element lock when posting the message so that any
1688 * (synchronous) message handlers can operate on the element */
1689 result = gst_bus_post (bus, message);
1690 gst_object_unref (bus);
1697 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element,
1698 "not posting message %p: no bus", message);
1699 GST_OBJECT_UNLOCK (element);
1700 gst_message_unref (message);
1706 * gst_element_post_message:
1707 * @element: a #GstElement posting the message
1708 * @message: (transfer full): a #GstMessage to post
1710 * Post a message on the element's #GstBus. This function takes ownership of the
1711 * message; if you want to access the message after this call, you should add an
1712 * additional reference before calling.
1714 * Returns: %TRUE if the message was successfully posted. The function returns
1715 * %FALSE if the element did not have a bus.
1720 gst_element_post_message (GstElement * element, GstMessage * message)
1722 GstElementClass *klass;
1724 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1725 g_return_val_if_fail (message != NULL, FALSE);
1727 klass = GST_ELEMENT_GET_CLASS (element);
1728 if (klass->post_message)
1729 return klass->post_message (element, message);
1735 * _gst_element_error_printf:
1736 * @format: the printf-like format to use, or %NULL
1738 * This function is only used internally by the gst_element_error() macro.
1740 * Returns: (transfer full): a newly allocated string, or %NULL if the format
1746 _gst_element_error_printf (const gchar * format, ...)
1757 va_start (args, format);
1759 len = __gst_vasprintf (&buffer, format, args);
1770 * gst_element_message_full:
1771 * @element: a #GstElement to send message from
1772 * @type: the #GstMessageType
1773 * @domain: the GStreamer GError domain this message belongs to
1774 * @code: the GError code belonging to the domain
1775 * @text: (allow-none) (transfer full): an allocated text string to be used
1776 * as a replacement for the default message connected to code,
1778 * @debug: (allow-none) (transfer full): an allocated debug message to be
1779 * used as a replacement for the default debugging information,
1781 * @file: the source code file where the error was generated
1782 * @function: the source code function where the error was generated
1783 * @line: the source code line where the error was generated
1785 * Post an error, warning or info message on the bus from inside an element.
1787 * @type must be of #GST_MESSAGE_ERROR, #GST_MESSAGE_WARNING or
1788 * #GST_MESSAGE_INFO.
1792 void gst_element_message_full
1793 (GstElement * element, GstMessageType type,
1794 GQuark domain, gint code, gchar * text,
1795 gchar * debug, const gchar * file, const gchar * function, gint line)
1797 GError *gerror = NULL;
1801 gboolean has_debug = TRUE;
1802 GstMessage *message = NULL;
1805 GST_CAT_DEBUG_OBJECT (GST_CAT_MESSAGE, element, "start");
1806 g_return_if_fail (GST_IS_ELEMENT (element));
1807 g_return_if_fail ((type == GST_MESSAGE_ERROR) ||
1808 (type == GST_MESSAGE_WARNING) || (type == GST_MESSAGE_INFO));
1810 /* check if we send the given text or the default error text */
1811 if ((text == NULL) || (text[0] == 0)) {
1812 /* text could have come from g_strdup_printf (""); */
1814 sent_text = gst_error_get_message (domain, code);
1818 /* construct a sent_debug with extra information from source */
1819 if ((debug == NULL) || (debug[0] == 0)) {
1820 /* debug could have come from g_strdup_printf (""); */
1824 name = gst_object_get_path_string (GST_OBJECT_CAST (element));
1826 sent_debug = g_strdup_printf ("%s(%d): %s (): %s:\n%s",
1827 file, line, function, name, debug);
1829 sent_debug = g_strdup_printf ("%s(%d): %s (): %s",
1830 file, line, function, name);
1834 /* create gerror and post message */
1835 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posting message: %s",
1837 gerror = g_error_new_literal (domain, code, sent_text);
1840 case GST_MESSAGE_ERROR:
1842 gst_message_new_error (GST_OBJECT_CAST (element), gerror, sent_debug);
1844 case GST_MESSAGE_WARNING:
1845 message = gst_message_new_warning (GST_OBJECT_CAST (element), gerror,
1848 case GST_MESSAGE_INFO:
1849 message = gst_message_new_info (GST_OBJECT_CAST (element), gerror,
1853 g_assert_not_reached ();
1856 gst_element_post_message (element, message);
1858 GST_CAT_INFO_OBJECT (GST_CAT_ERROR_SYSTEM, element, "posted %s message: %s",
1859 (type == GST_MESSAGE_ERROR ? "error" : "warning"), sent_text);
1862 g_error_free (gerror);
1863 g_free (sent_debug);
1868 * gst_element_is_locked_state:
1869 * @element: a #GstElement.
1871 * Checks if the state of an element is locked.
1872 * If the state of an element is locked, state changes of the parent don't
1873 * affect the element.
1874 * This way you can leave currently unused elements inside bins. Just lock their
1875 * state before changing the state from #GST_STATE_NULL.
1879 * Returns: TRUE, if the element's state is locked.
1882 gst_element_is_locked_state (GstElement * element)
1886 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1888 GST_OBJECT_LOCK (element);
1889 result = GST_ELEMENT_IS_LOCKED_STATE (element);
1890 GST_OBJECT_UNLOCK (element);
1896 * gst_element_set_locked_state:
1897 * @element: a #GstElement
1898 * @locked_state: TRUE to lock the element's state
1900 * Locks the state of an element, so state changes of the parent don't affect
1901 * this element anymore.
1905 * Returns: TRUE if the state was changed, FALSE if bad parameters were given
1906 * or the elements state-locking needed no change.
1909 gst_element_set_locked_state (GstElement * element, gboolean locked_state)
1913 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1915 GST_OBJECT_LOCK (element);
1916 old = GST_ELEMENT_IS_LOCKED_STATE (element);
1918 if (G_UNLIKELY (old == locked_state))
1922 GST_CAT_DEBUG (GST_CAT_STATES, "locking state of element %s",
1923 GST_ELEMENT_NAME (element));
1924 GST_OBJECT_FLAG_SET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1926 GST_CAT_DEBUG (GST_CAT_STATES, "unlocking state of element %s",
1927 GST_ELEMENT_NAME (element));
1928 GST_OBJECT_FLAG_UNSET (element, GST_ELEMENT_FLAG_LOCKED_STATE);
1930 GST_OBJECT_UNLOCK (element);
1936 GST_CAT_DEBUG (GST_CAT_STATES,
1937 "elements %s was already in locked state %d",
1938 GST_ELEMENT_NAME (element), old);
1939 GST_OBJECT_UNLOCK (element);
1946 * gst_element_sync_state_with_parent:
1947 * @element: a #GstElement.
1949 * Tries to change the state of the element to the same as its parent.
1950 * If this function returns FALSE, the state of element is undefined.
1952 * Returns: TRUE, if the element's state could be synced to the parent's state.
1957 gst_element_sync_state_with_parent (GstElement * element)
1961 GstStateChangeReturn ret;
1963 g_return_val_if_fail (GST_IS_ELEMENT (element), FALSE);
1965 if ((parent = GST_ELEMENT_CAST (gst_element_get_parent (element)))) {
1966 GstState parent_current, parent_pending;
1968 GST_OBJECT_LOCK (parent);
1969 parent_current = GST_STATE (parent);
1970 parent_pending = GST_STATE_PENDING (parent);
1971 GST_OBJECT_UNLOCK (parent);
1973 /* set to pending if there is one, else we set it to the current state of
1975 if (parent_pending != GST_STATE_VOID_PENDING)
1976 target = parent_pending;
1978 target = parent_current;
1980 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
1981 "syncing state (%s) to parent %s %s (%s, %s)",
1982 gst_element_state_get_name (GST_STATE (element)),
1983 GST_ELEMENT_NAME (parent), gst_element_state_get_name (target),
1984 gst_element_state_get_name (parent_current),
1985 gst_element_state_get_name (parent_pending));
1987 ret = gst_element_set_state (element, target);
1988 if (ret == GST_STATE_CHANGE_FAILURE)
1991 gst_object_unref (parent);
1995 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "element has no parent");
2002 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2003 "syncing state failed (%s)",
2004 gst_element_state_change_return_get_name (ret));
2005 gst_object_unref (parent);
2011 static GstStateChangeReturn
2012 gst_element_get_state_func (GstElement * element,
2013 GstState * state, GstState * pending, GstClockTime timeout)
2015 GstStateChangeReturn ret = GST_STATE_CHANGE_FAILURE;
2016 GstState old_pending;
2018 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "getting state, timeout %"
2019 GST_TIME_FORMAT, GST_TIME_ARGS (timeout));
2021 GST_OBJECT_LOCK (element);
2022 ret = GST_STATE_RETURN (element);
2023 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "RETURN is %s",
2024 gst_element_state_change_return_get_name (ret));
2026 /* we got an error, report immediately */
2027 if (ret == GST_STATE_CHANGE_FAILURE)
2030 /* we got no_preroll, report immediately */
2031 if (ret == GST_STATE_CHANGE_NO_PREROLL)
2034 /* no need to wait async if we are not async */
2035 if (ret != GST_STATE_CHANGE_ASYNC)
2038 old_pending = GST_STATE_PENDING (element);
2039 if (old_pending != GST_STATE_VOID_PENDING) {
2043 /* get cookie to detect state changes during waiting */
2044 cookie = element->state_cookie;
2046 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2047 "waiting for element to commit state");
2049 /* we have a pending state change, wait for it to complete */
2050 if (timeout != GST_CLOCK_TIME_NONE) {
2052 /* make timeout absolute */
2053 end_time = g_get_monotonic_time () + (timeout / 1000);
2054 signaled = GST_STATE_WAIT_UNTIL (element, end_time);
2056 GST_STATE_WAIT (element);
2061 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "timed out");
2062 /* timeout triggered */
2063 ret = GST_STATE_CHANGE_ASYNC;
2065 if (cookie != element->state_cookie)
2068 /* could be success or failure */
2069 if (old_pending == GST_STATE (element)) {
2070 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got success");
2071 ret = GST_STATE_CHANGE_SUCCESS;
2073 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "got failure");
2074 ret = GST_STATE_CHANGE_FAILURE;
2077 /* if nothing is pending anymore we can return SUCCESS */
2078 if (GST_STATE_PENDING (element) == GST_STATE_VOID_PENDING) {
2079 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "nothing pending");
2080 ret = GST_STATE_CHANGE_SUCCESS;
2086 *state = GST_STATE (element);
2088 *pending = GST_STATE_PENDING (element);
2090 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2091 "state current: %s, pending: %s, result: %s",
2092 gst_element_state_get_name (GST_STATE (element)),
2093 gst_element_state_get_name (GST_STATE_PENDING (element)),
2094 gst_element_state_change_return_get_name (ret));
2095 GST_OBJECT_UNLOCK (element);
2102 *state = GST_STATE_VOID_PENDING;
2104 *pending = GST_STATE_VOID_PENDING;
2106 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "interruped");
2108 GST_OBJECT_UNLOCK (element);
2110 return GST_STATE_CHANGE_FAILURE;
2115 * gst_element_get_state:
2116 * @element: a #GstElement to get the state of.
2117 * @state: (out) (allow-none): a pointer to #GstState to hold the state.
2119 * @pending: (out) (allow-none): a pointer to #GstState to hold the pending
2120 * state. Can be %NULL.
2121 * @timeout: a #GstClockTime to specify the timeout for an async
2122 * state change or %GST_CLOCK_TIME_NONE for infinite timeout.
2124 * Gets the state of the element.
2126 * For elements that performed an ASYNC state change, as reported by
2127 * gst_element_set_state(), this function will block up to the
2128 * specified timeout value for the state change to complete.
2129 * If the element completes the state change or goes into
2130 * an error, this function returns immediately with a return value of
2131 * %GST_STATE_CHANGE_SUCCESS or %GST_STATE_CHANGE_FAILURE respectively.
2133 * For elements that did not return %GST_STATE_CHANGE_ASYNC, this function
2134 * returns the current and pending state immediately.
2136 * This function returns %GST_STATE_CHANGE_NO_PREROLL if the element
2137 * successfully changed its state but is not able to provide data yet.
2138 * This mostly happens for live sources that only produce data in
2139 * %GST_STATE_PLAYING. While the state change return is equivalent to
2140 * %GST_STATE_CHANGE_SUCCESS, it is returned to the application to signal that
2141 * some sink elements might not be able to complete their state change because
2142 * an element is not producing data to complete the preroll. When setting the
2143 * element to playing, the preroll will complete and playback will start.
2145 * Returns: %GST_STATE_CHANGE_SUCCESS if the element has no more pending state
2146 * and the last state change succeeded, %GST_STATE_CHANGE_ASYNC if the
2147 * element is still performing a state change or
2148 * %GST_STATE_CHANGE_FAILURE if the last state change failed.
2152 GstStateChangeReturn
2153 gst_element_get_state (GstElement * element,
2154 GstState * state, GstState * pending, GstClockTime timeout)
2156 GstElementClass *oclass;
2157 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2159 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2161 oclass = GST_ELEMENT_GET_CLASS (element);
2163 if (oclass->get_state)
2164 result = (oclass->get_state) (element, state, pending, timeout);
2170 * gst_element_abort_state:
2171 * @element: a #GstElement to abort the state of.
2173 * Abort the state change of the element. This function is used
2174 * by elements that do asynchronous state changes and find out
2175 * something is wrong.
2177 * This function should be called with the STATE_LOCK held.
2182 gst_element_abort_state (GstElement * element)
2186 #ifndef GST_DISABLE_GST_DEBUG
2190 g_return_if_fail (GST_IS_ELEMENT (element));
2192 GST_OBJECT_LOCK (element);
2193 pending = GST_STATE_PENDING (element);
2195 if (pending == GST_STATE_VOID_PENDING ||
2196 GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2197 goto nothing_aborted;
2199 #ifndef GST_DISABLE_GST_DEBUG
2200 old_state = GST_STATE (element);
2202 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2203 "aborting state from %s to %s", gst_element_state_get_name (old_state),
2204 gst_element_state_get_name (pending));
2208 GST_STATE_RETURN (element) = GST_STATE_CHANGE_FAILURE;
2210 GST_STATE_BROADCAST (element);
2211 GST_OBJECT_UNLOCK (element);
2217 GST_OBJECT_UNLOCK (element);
2222 /* Not static because GstBin has manual state handling too */
2224 _priv_gst_element_state_changed (GstElement * element, GstState oldstate,
2225 GstState newstate, GstState pending)
2227 GstElementClass *klass = GST_ELEMENT_GET_CLASS (element);
2228 GstMessage *message;
2230 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2231 "notifying about state-changed %s to %s (%s pending)",
2232 gst_element_state_get_name (oldstate),
2233 gst_element_state_get_name (newstate),
2234 gst_element_state_get_name (pending));
2236 if (klass->state_changed)
2237 klass->state_changed (element, oldstate, newstate, pending);
2239 message = gst_message_new_state_changed (GST_OBJECT_CAST (element),
2240 oldstate, newstate, pending);
2241 gst_element_post_message (element, message);
2245 * gst_element_continue_state:
2246 * @element: a #GstElement to continue the state change of.
2247 * @ret: The previous state return value
2249 * Commit the state change of the element and proceed to the next
2250 * pending state if any. This function is used
2251 * by elements that do asynchronous state changes.
2252 * The core will normally call this method automatically when an
2253 * element returned %GST_STATE_CHANGE_SUCCESS from the state change function.
2255 * If after calling this method the element still has not reached
2256 * the pending state, the next state change is performed.
2258 * This method is used internally and should normally not be called by plugins
2261 * Returns: The result of the commit state change.
2265 GstStateChangeReturn
2266 gst_element_continue_state (GstElement * element, GstStateChangeReturn ret)
2268 GstStateChangeReturn old_ret;
2269 GstState old_state, old_next;
2270 GstState current, next, pending;
2271 GstStateChange transition;
2273 GST_OBJECT_LOCK (element);
2274 old_ret = GST_STATE_RETURN (element);
2275 GST_STATE_RETURN (element) = ret;
2276 pending = GST_STATE_PENDING (element);
2278 /* check if there is something to commit */
2279 if (pending == GST_STATE_VOID_PENDING)
2280 goto nothing_pending;
2282 old_state = GST_STATE (element);
2283 /* this is the state we should go to next */
2284 old_next = GST_STATE_NEXT (element);
2285 /* update current state */
2286 current = GST_STATE (element) = old_next;
2288 /* see if we reached the final state */
2289 if (pending == current)
2292 next = GST_STATE_GET_NEXT (current, pending);
2293 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2295 GST_STATE_NEXT (element) = next;
2297 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2298 GST_OBJECT_UNLOCK (element);
2300 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2301 "committing state from %s to %s, pending %s, next %s",
2302 gst_element_state_get_name (old_state),
2303 gst_element_state_get_name (old_next),
2304 gst_element_state_get_name (pending), gst_element_state_get_name (next));
2306 _priv_gst_element_state_changed (element, old_state, old_next, pending);
2308 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2309 "continue state change %s to %s, final %s",
2310 gst_element_state_get_name (current),
2311 gst_element_state_get_name (next), gst_element_state_get_name (pending));
2313 ret = gst_element_change_state (element, transition);
2319 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element, "nothing pending");
2320 GST_OBJECT_UNLOCK (element);
2325 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2326 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2328 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2329 "completed state change to %s", gst_element_state_get_name (pending));
2330 GST_OBJECT_UNLOCK (element);
2332 /* don't post silly messages with the same state. This can happen
2333 * when an element state is changed to what it already was. For bins
2334 * this can be the result of a lost state, which we check with the
2335 * previous return value.
2336 * We do signal the cond though as a _get_state() might be blocking
2338 if (old_state != old_next || old_ret == GST_STATE_CHANGE_ASYNC)
2339 _priv_gst_element_state_changed (element, old_state, old_next,
2340 GST_STATE_VOID_PENDING);
2342 GST_STATE_BROADCAST (element);
2349 * gst_element_lost_state:
2350 * @element: a #GstElement the state is lost of
2352 * Brings the element to the lost state. The current state of the
2353 * element is copied to the pending state so that any call to
2354 * gst_element_get_state() will return %GST_STATE_CHANGE_ASYNC.
2356 * An ASYNC_START message is posted. If the element was PLAYING, it will
2357 * go to PAUSED. The element will be restored to its PLAYING state by
2358 * the parent pipeline when it prerolls again.
2360 * This is mostly used for elements that lost their preroll buffer
2361 * in the %GST_STATE_PAUSED or %GST_STATE_PLAYING state after a flush,
2362 * they will go to their pending state again when a new preroll buffer is
2363 * queued. This function can only be called when the element is currently
2364 * not in error or an async state change.
2366 * This function is used internally and should normally not be called from
2367 * plugins or applications.
2370 gst_element_lost_state (GstElement * element)
2372 GstState old_state, new_state;
2373 GstMessage *message;
2375 g_return_if_fail (GST_IS_ELEMENT (element));
2377 GST_OBJECT_LOCK (element);
2378 if (GST_STATE_RETURN (element) == GST_STATE_CHANGE_FAILURE)
2381 if (GST_STATE_PENDING (element) != GST_STATE_VOID_PENDING)
2382 goto only_async_start;
2384 old_state = GST_STATE (element);
2386 /* when we were PLAYING, the new state is PAUSED. We will also not
2387 * automatically go to PLAYING but let the parent bin(s) set us to PLAYING
2388 * when we preroll. */
2389 if (old_state > GST_STATE_PAUSED)
2390 new_state = GST_STATE_PAUSED;
2392 new_state = old_state;
2394 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2395 "lost state of %s to %s", gst_element_state_get_name (old_state),
2396 gst_element_state_get_name (new_state));
2398 GST_STATE (element) = new_state;
2399 GST_STATE_NEXT (element) = new_state;
2400 GST_STATE_PENDING (element) = new_state;
2401 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2402 GST_OBJECT_UNLOCK (element);
2404 _priv_gst_element_state_changed (element, new_state, new_state, new_state);
2406 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2407 gst_element_post_message (element, message);
2413 GST_OBJECT_UNLOCK (element);
2418 GST_OBJECT_UNLOCK (element);
2420 message = gst_message_new_async_start (GST_OBJECT_CAST (element));
2421 gst_element_post_message (element, message);
2427 * gst_element_set_state:
2428 * @element: a #GstElement to change state of.
2429 * @state: the element's new #GstState.
2431 * Sets the state of the element. This function will try to set the
2432 * requested state by going through all the intermediary states and calling
2433 * the class's state change function for each.
2435 * This function can return #GST_STATE_CHANGE_ASYNC, in which case the
2436 * element will perform the remainder of the state change asynchronously in
2438 * An application can use gst_element_get_state() to wait for the completion
2439 * of the state change or it can wait for a %GST_MESSAGE_ASYNC_DONE or
2440 * %GST_MESSAGE_STATE_CHANGED on the bus.
2442 * State changes to %GST_STATE_READY or %GST_STATE_NULL never return
2443 * #GST_STATE_CHANGE_ASYNC.
2445 * Returns: Result of the state change using #GstStateChangeReturn.
2449 GstStateChangeReturn
2450 gst_element_set_state (GstElement * element, GstState state)
2452 GstElementClass *oclass;
2453 GstStateChangeReturn result = GST_STATE_CHANGE_FAILURE;
2455 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2457 oclass = GST_ELEMENT_GET_CLASS (element);
2459 if (oclass->set_state)
2460 result = (oclass->set_state) (element, state);
2466 * default set state function, calculates the next state based
2467 * on current state and calls the change_state function
2469 static GstStateChangeReturn
2470 gst_element_set_state_func (GstElement * element, GstState state)
2472 GstState current, next, old_pending;
2473 GstStateChangeReturn ret;
2474 GstStateChange transition;
2475 GstStateChangeReturn old_ret;
2477 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2479 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "set_state to %s",
2480 gst_element_state_get_name (state));
2482 /* state lock is taken to protect the set_state() and get_state()
2483 * procedures, it does not lock any variables. */
2484 GST_STATE_LOCK (element);
2486 /* now calculate how to get to the new state */
2487 GST_OBJECT_LOCK (element);
2488 old_ret = GST_STATE_RETURN (element);
2489 /* previous state change returned an error, remove all pending
2490 * and next states */
2491 if (old_ret == GST_STATE_CHANGE_FAILURE) {
2492 GST_STATE_NEXT (element) = GST_STATE_VOID_PENDING;
2493 GST_STATE_PENDING (element) = GST_STATE_VOID_PENDING;
2494 GST_STATE_RETURN (element) = GST_STATE_CHANGE_SUCCESS;
2497 current = GST_STATE (element);
2498 next = GST_STATE_NEXT (element);
2499 old_pending = GST_STATE_PENDING (element);
2501 /* this is the (new) state we should go to. TARGET is the last state we set on
2503 if (state != GST_STATE_TARGET (element)) {
2504 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2505 "setting target state to %s", gst_element_state_get_name (state));
2506 GST_STATE_TARGET (element) = state;
2507 /* increment state cookie so that we can track each state change. We only do
2508 * this if this is actually a new state change. */
2509 element->state_cookie++;
2511 GST_STATE_PENDING (element) = state;
2513 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2514 "current %s, old_pending %s, next %s, old return %s",
2515 gst_element_state_get_name (current),
2516 gst_element_state_get_name (old_pending),
2517 gst_element_state_get_name (next),
2518 gst_element_state_change_return_get_name (old_ret));
2520 /* if the element was busy doing a state change, we just update the
2521 * target state, it'll get to it async then. */
2522 if (old_pending != GST_STATE_VOID_PENDING) {
2523 /* upwards state change will happen ASYNC */
2524 if (old_pending <= state)
2526 /* element is going to this state already */
2527 else if (next == state)
2529 /* element was performing an ASYNC upward state change and
2530 * we request to go downward again. Start from the next pending
2532 else if (next > state
2533 && GST_STATE_RETURN (element) == GST_STATE_CHANGE_ASYNC) {
2537 next = GST_STATE_GET_NEXT (current, state);
2538 /* now we store the next state */
2539 GST_STATE_NEXT (element) = next;
2540 /* mark busy, we need to check that there is actually a state change
2541 * to be done else we could accidentally override SUCCESS/NO_PREROLL and
2542 * the default element change_state function has no way to know what the
2543 * old value was... could consider this a FIXME...*/
2544 if (current != next)
2545 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2547 transition = (GstStateChange) GST_STATE_TRANSITION (current, next);
2549 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2550 "%s: setting state from %s to %s",
2551 (next != state ? "intermediate" : "final"),
2552 gst_element_state_get_name (current), gst_element_state_get_name (next));
2554 /* now signal any waiters, they will error since the cookie was incremented */
2555 GST_STATE_BROADCAST (element);
2557 GST_OBJECT_UNLOCK (element);
2559 ret = gst_element_change_state (element, transition);
2561 GST_STATE_UNLOCK (element);
2563 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element, "returned %s",
2564 gst_element_state_change_return_get_name (ret));
2570 GST_STATE_RETURN (element) = GST_STATE_CHANGE_ASYNC;
2571 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2572 "element was busy with async state change");
2573 GST_OBJECT_UNLOCK (element);
2575 GST_STATE_UNLOCK (element);
2577 return GST_STATE_CHANGE_ASYNC;
2582 * gst_element_change_state:
2583 * @element: a #GstElement
2584 * @transition: the requested transition
2586 * Perform @transition on @element.
2588 * This function must be called with STATE_LOCK held and is mainly used
2591 * Returns: the #GstStateChangeReturn of the state transition.
2593 GstStateChangeReturn
2594 gst_element_change_state (GstElement * element, GstStateChange transition)
2596 GstElementClass *oclass;
2597 GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
2599 oclass = GST_ELEMENT_GET_CLASS (element);
2601 /* call the state change function so it can set the state */
2602 if (oclass->change_state)
2603 ret = (oclass->change_state) (element, transition);
2605 ret = GST_STATE_CHANGE_FAILURE;
2608 case GST_STATE_CHANGE_FAILURE:
2609 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2610 "have FAILURE change_state return");
2611 /* state change failure */
2612 gst_element_abort_state (element);
2614 case GST_STATE_CHANGE_ASYNC:
2618 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2619 "element will change state ASYNC");
2621 target = GST_STATE_TARGET (element);
2623 if (target > GST_STATE_READY)
2626 /* else we just continue the state change downwards */
2627 GST_CAT_INFO_OBJECT (GST_CAT_STATES, element,
2628 "forcing commit state %s <= %s",
2629 gst_element_state_get_name (target),
2630 gst_element_state_get_name (GST_STATE_READY));
2632 ret = gst_element_continue_state (element, GST_STATE_CHANGE_SUCCESS);
2635 case GST_STATE_CHANGE_SUCCESS:
2636 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2637 "element changed state SUCCESS");
2638 /* we can commit the state now which will proceeed to
2640 ret = gst_element_continue_state (element, ret);
2642 case GST_STATE_CHANGE_NO_PREROLL:
2643 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2644 "element changed state NO_PREROLL");
2645 /* we can commit the state now which will proceeed to
2647 ret = gst_element_continue_state (element, ret);
2650 goto invalid_return;
2653 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit state change %d", ret);
2658 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element, "exit async state change %d",
2666 GST_OBJECT_LOCK (element);
2667 /* somebody added a GST_STATE_ and forgot to do stuff here ! */
2668 g_critical ("%s: unknown return value %d from a state change function",
2669 GST_ELEMENT_NAME (element), ret);
2671 /* we are in error now */
2672 ret = GST_STATE_CHANGE_FAILURE;
2673 GST_STATE_RETURN (element) = ret;
2674 GST_OBJECT_UNLOCK (element);
2680 /* gst_iterator_fold functions for pads_activate
2681 * Stop the iterator if activating one pad failed. */
2683 activate_pads (const GValue * vpad, GValue * ret, gboolean * active)
2685 GstPad *pad = g_value_get_object (vpad);
2686 gboolean cont = TRUE;
2688 if (!(cont = gst_pad_set_active (pad, *active)))
2689 g_value_set_boolean (ret, FALSE);
2694 /* returns false on error or early cutout of the fold, true if all
2695 * pads in @iter were (de)activated successfully. */
2697 iterator_activate_fold_with_resync (GstIterator * iter,
2698 GstIteratorFoldFunction func, gpointer user_data)
2700 GstIteratorResult ires;
2703 /* no need to unset this later, it's just a boolean */
2704 g_value_init (&ret, G_TYPE_BOOLEAN);
2705 g_value_set_boolean (&ret, TRUE);
2708 ires = gst_iterator_fold (iter, func, &ret, user_data);
2710 case GST_ITERATOR_RESYNC:
2711 /* need to reset the result again */
2712 g_value_set_boolean (&ret, TRUE);
2713 gst_iterator_resync (iter);
2715 case GST_ITERATOR_DONE:
2716 /* all pads iterated, return collected value */
2719 /* iterator returned _ERROR or premature end with _OK,
2720 * mark an error and exit */
2721 g_value_set_boolean (&ret, FALSE);
2726 /* return collected value */
2727 return g_value_get_boolean (&ret);
2730 /* is called with STATE_LOCK
2732 * Pads are activated from source pads to sinkpads.
2735 gst_element_pads_activate (GstElement * element, gboolean active)
2740 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2741 "%s pads", active ? "activate" : "deactivate");
2743 iter = gst_element_iterate_src_pads (element);
2745 iterator_activate_fold_with_resync (iter,
2746 (GstIteratorFoldFunction) activate_pads, &active);
2747 gst_iterator_free (iter);
2748 if (G_UNLIKELY (!res))
2751 iter = gst_element_iterate_sink_pads (element);
2753 iterator_activate_fold_with_resync (iter,
2754 (GstIteratorFoldFunction) activate_pads, &active);
2755 gst_iterator_free (iter);
2756 if (G_UNLIKELY (!res))
2759 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2760 "pad %sactivation successful", active ? "" : "de");
2767 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2768 "pad %sactivation failed", active ? "" : "de");
2773 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2774 "sink pads_activate failed");
2779 /* is called with STATE_LOCK */
2780 static GstStateChangeReturn
2781 gst_element_change_state_func (GstElement * element, GstStateChange transition)
2783 GstState state, next;
2784 GstStateChangeReturn result = GST_STATE_CHANGE_SUCCESS;
2786 g_return_val_if_fail (GST_IS_ELEMENT (element), GST_STATE_CHANGE_FAILURE);
2788 state = (GstState) GST_STATE_TRANSITION_CURRENT (transition);
2789 next = GST_STATE_TRANSITION_NEXT (transition);
2791 /* if the element already is in the given state, we just return success */
2792 if (next == GST_STATE_VOID_PENDING || state == next)
2795 GST_CAT_LOG_OBJECT (GST_CAT_STATES, element,
2796 "default handler tries setting state from %s to %s (%04x)",
2797 gst_element_state_get_name (state),
2798 gst_element_state_get_name (next), transition);
2800 switch (transition) {
2801 case GST_STATE_CHANGE_NULL_TO_READY:
2803 case GST_STATE_CHANGE_READY_TO_PAUSED:
2804 if (!gst_element_pads_activate (element, TRUE)) {
2805 result = GST_STATE_CHANGE_FAILURE;
2808 case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
2810 case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
2812 case GST_STATE_CHANGE_PAUSED_TO_READY:
2813 case GST_STATE_CHANGE_READY_TO_NULL:
2814 /* deactivate pads in both cases, since they are activated on
2815 ready->paused but the element might not have made it to paused */
2816 if (!gst_element_pads_activate (element, FALSE)) {
2817 result = GST_STATE_CHANGE_FAILURE;
2821 /* this will catch real but unhandled state changes;
2822 * can only be caused by:
2823 * - a new state was added
2824 * - somehow the element was asked to jump across an intermediate state
2826 g_warning ("Unhandled state change from %s to %s",
2827 gst_element_state_get_name (state),
2828 gst_element_state_get_name (next));
2835 GST_OBJECT_LOCK (element);
2836 result = GST_STATE_RETURN (element);
2837 GST_CAT_DEBUG_OBJECT (GST_CAT_STATES, element,
2838 "element is already in the %s state",
2839 gst_element_state_get_name (state));
2840 GST_OBJECT_UNLOCK (element);
2847 * gst_element_get_factory:
2848 * @element: a #GstElement to request the element factory of.
2850 * Retrieves the factory that was used to create this element.
2852 * Returns: (transfer none): the #GstElementFactory used for creating this
2853 * element. no refcounting is needed.
2856 gst_element_get_factory (GstElement * element)
2858 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
2860 return GST_ELEMENT_GET_CLASS (element)->elementfactory;
2864 gst_element_dispose (GObject * object)
2866 GstElement *element = GST_ELEMENT_CAST (object);
2869 GstElementClass *oclass;
2872 oclass = GST_ELEMENT_GET_CLASS (element);
2874 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "dispose");
2876 if (GST_STATE (element) != GST_STATE_NULL)
2879 /* start by releasing all request pads, this might also remove some dynamic
2881 walk = element->pads;
2883 GstPad *pad = GST_PAD_CAST (walk->data);
2887 if (oclass->release_pad && GST_PAD_PAD_TEMPLATE (pad) &&
2888 GST_PAD_TEMPLATE_PRESENCE (GST_PAD_PAD_TEMPLATE (pad))
2889 == GST_PAD_REQUEST) {
2890 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2891 "removing request pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2892 oclass->release_pad (element, pad);
2894 /* in case the release_pad function removed the next pad too */
2895 if (walk && g_list_position (element->pads, walk) == -1)
2896 walk = element->pads;
2899 /* remove the remaining pads */
2900 while (element->pads) {
2901 GstPad *pad = GST_PAD_CAST (element->pads->data);
2902 GST_CAT_DEBUG_OBJECT (GST_CAT_ELEMENT_PADS, element,
2903 "removing pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2904 if (!gst_element_remove_pad (element, pad)) {
2905 /* only happens when someone unparented our pad.. */
2906 g_critical ("failed to remove pad %s:%s", GST_DEBUG_PAD_NAME (pad));
2911 GST_OBJECT_LOCK (element);
2912 clock_p = &element->clock;
2913 bus_p = &element->bus;
2914 gst_object_replace ((GstObject **) clock_p, NULL);
2915 gst_object_replace ((GstObject **) bus_p, NULL);
2916 gst_context_replace (&element->context, NULL);
2917 GST_OBJECT_UNLOCK (element);
2919 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "parent class dispose");
2921 G_OBJECT_CLASS (parent_class)->dispose (object);
2930 is_locked = GST_ELEMENT_IS_LOCKED_STATE (element);
2932 ("\nTrying to dispose element %s, but it is in %s%s instead of the NULL"
2934 "You need to explicitly set elements to the NULL state before\n"
2935 "dropping the final reference, to allow them to clean up.\n"
2936 "This problem may also be caused by a refcounting bug in the\n"
2937 "application or some element.\n",
2938 GST_OBJECT_NAME (element),
2939 gst_element_state_get_name (GST_STATE (element)),
2940 is_locked ? " (locked)" : "");
2946 gst_element_finalize (GObject * object)
2948 GstElement *element = GST_ELEMENT_CAST (object);
2950 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize");
2952 g_cond_clear (&element->state_cond);
2953 g_rec_mutex_clear (&element->state_lock);
2955 GST_CAT_INFO_OBJECT (GST_CAT_REFCOUNTING, element, "finalize parent");
2957 G_OBJECT_CLASS (parent_class)->finalize (object);
2961 gst_element_set_bus_func (GstElement * element, GstBus * bus)
2965 g_return_if_fail (GST_IS_ELEMENT (element));
2967 GST_CAT_DEBUG_OBJECT (GST_CAT_PARENTAGE, element, "setting bus to %p", bus);
2969 GST_OBJECT_LOCK (element);
2970 bus_p = &GST_ELEMENT_BUS (element);
2971 gst_object_replace ((GstObject **) bus_p, GST_OBJECT_CAST (bus));
2972 GST_OBJECT_UNLOCK (element);
2976 * gst_element_set_bus:
2977 * @element: a #GstElement to set the bus of.
2978 * @bus: (transfer none): the #GstBus to set.
2980 * Sets the bus of the element. Increases the refcount on the bus.
2981 * For internal use only, unless you're testing elements.
2986 gst_element_set_bus (GstElement * element, GstBus * bus)
2988 GstElementClass *oclass;
2990 g_return_if_fail (GST_IS_ELEMENT (element));
2992 oclass = GST_ELEMENT_GET_CLASS (element);
2994 if (oclass->set_bus)
2995 oclass->set_bus (element, bus);
2999 * gst_element_get_bus:
3000 * @element: a #GstElement to get the bus of.
3002 * Returns the bus of the element. Note that only a #GstPipeline will provide a
3003 * bus for the application.
3005 * Returns: (transfer full): the element's #GstBus. unref after usage.
3010 gst_element_get_bus (GstElement * element)
3012 GstBus *result = NULL;
3014 g_return_val_if_fail (GST_IS_ELEMENT (element), result);
3016 GST_OBJECT_LOCK (element);
3017 if ((result = GST_ELEMENT_BUS (element)))
3018 gst_object_ref (result);
3019 GST_OBJECT_UNLOCK (element);
3021 GST_CAT_DEBUG_OBJECT (GST_CAT_BUS, element, "got bus %" GST_PTR_FORMAT,
3028 gst_element_set_context_func (GstElement * element, GstContext * context)
3030 GST_OBJECT_LOCK (element);
3031 gst_context_replace (&element->context, context);
3032 GST_OBJECT_UNLOCK (element);
3036 * gst_element_set_context:
3037 * @element: a #GstElement to set the context of.
3038 * @context: (transfer none): the #GstContext to set.
3040 * Sets the context of the element. Increases the refcount of the context.
3045 gst_element_set_context (GstElement * element, GstContext * context)
3047 GstElementClass *oclass;
3049 g_return_if_fail (GST_IS_ELEMENT (element));
3051 oclass = GST_ELEMENT_GET_CLASS (element);
3053 GST_CAT_DEBUG_OBJECT (GST_CAT_CONTEXT, element,
3054 "set context %p %" GST_PTR_FORMAT, context,
3055 gst_context_get_structure (context));
3057 if (oclass->set_context)
3058 oclass->set_context (element, context);
3062 * gst_element_get_context:
3063 * @element: a #GstElement to get the context from.
3065 * Gets the current context of the element.
3069 * Returns: (transfer full): The current context of the element
3072 gst_element_get_context (GstElement * element)
3074 GstContext *context = NULL;
3076 g_return_val_if_fail (GST_IS_ELEMENT (element), NULL);
3078 GST_OBJECT_LOCK (element);
3079 if (element->context)
3080 context = gst_context_ref (element->context);
3081 GST_OBJECT_UNLOCK (element);