2 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
3 * 2000 Wim Taymans <wtay@chello.be>
4 * 2003 Benjamin Otte <in7y118@public.uni-hamburg.de>
6 * gstelementfactory.c: GstElementFactory object, support routines
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Library General Public
10 * License as published by the Free Software Foundation; either
11 * version 2 of the License, or (at your option) any later version.
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Library General Public License for more details.
18 * You should have received a copy of the GNU Library General Public
19 * License along with this library; if not, write to the
20 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
21 * Boston, MA 02111-1307, USA.
25 * SECTION:gstelementfactory
26 * @short_description: Create GstElements from a factory
27 * @see_also: #GstElement, #GstPlugin, #GstPluginFeature, #GstPadTemplate.
29 * #GstElementFactory is used to create instances of elements. A
30 * GstElementfactory can be added to a #GstPlugin as it is also a
33 * Use the gst_element_factory_find() and gst_element_factory_create()
34 * functions to create element instances or use gst_element_factory_make() as a
35 * convenient shortcut.
37 * The following code example shows you how to create a GstFileSrc element.
40 * <title>Using an element factory</title>
41 * <programlisting language="c">
42 * #include <gst/gst.h>
45 * GstElementFactory *srcfactory;
47 * gst_init (&argc, &argv);
49 * srcfactory = gst_element_factory_find ("filesrc");
50 * g_return_if_fail (srcfactory != NULL);
51 * src = gst_element_factory_create (srcfactory, "src");
52 * g_return_if_fail (src != NULL);
57 * Last reviewed on 2005-11-23 (0.9.5)
60 #include "gst_private.h"
62 #include "gstelement.h"
63 #include "gstelementdetails.h"
66 #include "gstregistry.h"
69 #include "glib-compat-private.h"
71 GST_DEBUG_CATEGORY_STATIC (element_factory_debug);
72 #define GST_CAT_DEFAULT element_factory_debug
74 static void gst_element_factory_finalize (GObject * object);
75 static void gst_element_factory_cleanup (GstElementFactory * factory);
77 /* static guint gst_element_factory_signals[LAST_SIGNAL] = { 0 }; */
79 /* this is defined in gstelement.c */
80 extern GQuark _gst_elementclass_factory;
84 GST_DEBUG_CATEGORY_INIT (element_factory_debug, "GST_ELEMENT_FACTORY", \
85 GST_DEBUG_BOLD | GST_DEBUG_FG_WHITE | GST_DEBUG_BG_RED, \
86 "element factories keep information about installed elements"); \
89 G_DEFINE_TYPE_WITH_CODE (GstElementFactory, gst_element_factory,
90 GST_TYPE_PLUGIN_FEATURE, _do_init);
93 gst_element_factory_class_init (GstElementFactoryClass * klass)
95 GObjectClass *gobject_class = (GObjectClass *) klass;
97 gobject_class->finalize = gst_element_factory_finalize;
101 gst_element_factory_init (GstElementFactory * factory)
103 factory->staticpadtemplates = NULL;
104 factory->numpadtemplates = 0;
106 factory->uri_type = GST_URI_UNKNOWN;
107 factory->uri_protocols = NULL;
109 factory->interfaces = NULL;
113 gst_element_factory_finalize (GObject * object)
115 GstElementFactory *factory = GST_ELEMENT_FACTORY (object);
117 gst_element_factory_cleanup (factory);
118 G_OBJECT_CLASS (gst_element_factory_parent_class)->finalize (object);
122 * gst_element_factory_find:
123 * @name: name of factory to find
125 * Search for an element factory of the given name. Refs the returned
126 * element factory; caller is responsible for unreffing.
128 * Returns: #GstElementFactory if found, NULL otherwise
131 gst_element_factory_find (const gchar * name)
133 GstPluginFeature *feature;
135 g_return_val_if_fail (name != NULL, NULL);
137 feature = gst_registry_find_feature (gst_registry_get_default (), name,
138 GST_TYPE_ELEMENT_FACTORY);
140 return GST_ELEMENT_FACTORY (feature);
142 /* this isn't an error, for instance when you query if an element factory is
144 GST_LOG ("no such element factory \"%s\"", name);
149 gst_element_factory_cleanup (GstElementFactory * factory)
153 __gst_element_details_clear (&factory->details);
154 if (factory->meta_data) {
155 gst_structure_free ((GstStructure *) factory->meta_data);
156 factory->meta_data = NULL;
159 factory->type = G_TYPE_INVALID;
162 for (item = factory->staticpadtemplates; item; item = item->next) {
163 GstStaticPadTemplate *templ = item->data;
164 GstCaps *caps = (GstCaps *) & (templ->static_caps);
166 g_free ((gchar *) templ->static_caps.string);
168 /* FIXME: this is not threadsafe */
169 if (caps->refcount == 1) {
170 GstStructure *structure;
173 for (i = 0; i < caps->structs->len; i++) {
174 structure = (GstStructure *) gst_caps_get_structure (caps, i);
175 gst_structure_set_parent_refcount (structure, NULL);
176 gst_structure_free (structure);
178 g_ptr_array_free (caps->structs, TRUE);
181 g_slice_free (GstStaticPadTemplate, templ);
183 g_list_free (factory->staticpadtemplates);
184 factory->staticpadtemplates = NULL;
185 factory->numpadtemplates = 0;
186 factory->uri_type = GST_URI_UNKNOWN;
187 if (factory->uri_protocols) {
188 g_strfreev (factory->uri_protocols);
189 factory->uri_protocols = NULL;
192 g_list_foreach (factory->interfaces, (GFunc) g_free, NULL);
193 g_list_free (factory->interfaces);
194 factory->interfaces = NULL;
198 * gst_element_register:
199 * @plugin: #GstPlugin to register the element with, or NULL for a static
200 * element (note that passing NULL only works in GStreamer 0.10.13 and later)
201 * @name: name of elements of this type
202 * @rank: rank of element (higher rank means more importance when autoplugging)
203 * @type: GType of element to register
205 * Create a new elementfactory capable of instantiating objects of the
206 * @type and add the factory to @plugin.
208 * Returns: TRUE, if the registering succeeded, FALSE on error
211 gst_element_register (GstPlugin * plugin, const gchar * name, guint rank,
214 GstPluginFeature *existing_feature;
215 GstRegistry *registry;
216 GstElementFactory *factory;
218 guint n_interfaces, i;
219 GstElementClass *klass;
222 g_return_val_if_fail (name != NULL, FALSE);
223 g_return_val_if_fail (g_type_is_a (type, GST_TYPE_ELEMENT), FALSE);
225 registry = gst_registry_get_default ();
227 /* check if feature already exists, if it exists there is no need to update it
228 * when the registry is getting updated, outdated plugins and all their
229 * features are removed and readded.
231 existing_feature = gst_registry_lookup_feature (registry, name);
232 if (existing_feature) {
233 GST_DEBUG_OBJECT (registry, "update existing feature %p (%s)",
234 existing_feature, name);
235 factory = GST_ELEMENT_FACTORY_CAST (existing_feature);
236 factory->type = type;
237 existing_feature->loaded = TRUE;
238 g_type_set_qdata (type, _gst_elementclass_factory, factory);
239 gst_object_unref (existing_feature);
244 GST_ELEMENT_FACTORY_CAST (g_object_newv (GST_TYPE_ELEMENT_FACTORY, 0,
246 gst_plugin_feature_set_name (GST_PLUGIN_FEATURE_CAST (factory), name);
247 GST_LOG_OBJECT (factory, "Created new elementfactory for type %s",
250 /* provide info needed during class structure setup */
251 g_type_set_qdata (type, _gst_elementclass_factory, factory);
252 klass = GST_ELEMENT_CLASS (g_type_class_ref (type));
253 if ((klass->details.longname == NULL) ||
254 (klass->details.klass == NULL) || (klass->details.author == NULL))
257 factory->type = type;
258 __gst_element_details_copy (&factory->details, &klass->details);
259 if (klass->meta_data) {
260 factory->meta_data = gst_structure_copy ((GstStructure *) klass->meta_data);
262 factory->meta_data = NULL;
264 for (item = klass->padtemplates; item; item = item->next) {
265 GstPadTemplate *templ = item->data;
266 GstStaticPadTemplate *newt;
268 newt = g_slice_new (GstStaticPadTemplate);
269 newt->name_template = g_intern_string (templ->name_template);
270 newt->direction = templ->direction;
271 newt->presence = templ->presence;
272 newt->static_caps.caps.refcount = 0;
273 newt->static_caps.string = gst_caps_to_string (templ->caps);
274 factory->staticpadtemplates =
275 g_list_append (factory->staticpadtemplates, newt);
277 factory->numpadtemplates = klass->numpadtemplates;
279 /* special stuff for URI handling */
280 if (g_type_is_a (type, GST_TYPE_URI_HANDLER)) {
281 GstURIHandlerInterface *iface = (GstURIHandlerInterface *)
282 g_type_interface_peek (klass, GST_TYPE_URI_HANDLER);
284 if (!iface || (!iface->get_type && !iface->get_type_full) ||
285 (!iface->get_protocols && !iface->get_protocols_full))
288 factory->uri_type = iface->get_type ();
289 else if (iface->get_type_full)
290 factory->uri_type = iface->get_type_full (factory->type);
291 if (!GST_URI_TYPE_IS_VALID (factory->uri_type))
293 if (iface->get_protocols)
294 factory->uri_protocols = g_strdupv (iface->get_protocols ());
295 else if (iface->get_protocols_full)
296 factory->uri_protocols = iface->get_protocols_full (factory->type);
297 if (!factory->uri_protocols)
301 interfaces = g_type_interfaces (type, &n_interfaces);
302 for (i = 0; i < n_interfaces; i++) {
303 __gst_element_factory_add_interface (factory, g_type_name (interfaces[i]));
307 if (plugin && plugin->desc.name) {
308 GST_PLUGIN_FEATURE_CAST (factory)->plugin_name = plugin->desc.name;
310 GST_PLUGIN_FEATURE_CAST (factory)->plugin_name = "NULL";
312 gst_plugin_feature_set_rank (GST_PLUGIN_FEATURE_CAST (factory), rank);
313 GST_PLUGIN_FEATURE_CAST (factory)->loaded = TRUE;
315 gst_registry_add_feature (registry, GST_PLUGIN_FEATURE_CAST (factory));
322 GST_WARNING_OBJECT (factory, "error with uri handler!");
323 gst_element_factory_cleanup (factory);
329 GST_WARNING_OBJECT (factory,
330 "The GstElementDetails don't seem to have been set properly");
331 gst_element_factory_cleanup (factory);
337 * gst_element_factory_create:
338 * @factory: factory to instantiate
339 * @name: name of new element
341 * Create a new element of the type defined by the given elementfactory.
342 * It will be given the name supplied, since all elements require a name as
343 * their first argument.
345 * Returns: new #GstElement or NULL if the element couldn't be created
348 gst_element_factory_create (GstElementFactory * factory, const gchar * name)
351 GstElementClass *oclass;
352 GstElementFactory *newfactory;
354 g_return_val_if_fail (factory != NULL, NULL);
357 GST_ELEMENT_FACTORY (gst_plugin_feature_load (GST_PLUGIN_FEATURE
360 if (newfactory == NULL)
363 factory = newfactory;
366 GST_INFO ("creating element \"%s\" named \"%s\"",
367 GST_PLUGIN_FEATURE_NAME (factory), GST_STR_NULL (name));
369 GST_INFO ("creating element \"%s\"", GST_PLUGIN_FEATURE_NAME (factory));
371 if (factory->type == 0)
374 /* create an instance of the element, cast so we don't assert on NULL
375 * also set name as early as we can
379 GST_ELEMENT_CAST (g_object_new (factory->type, "name", name, NULL));
381 element = GST_ELEMENT_CAST (g_object_newv (factory->type, 0, NULL));
382 if (G_UNLIKELY (element == NULL))
385 /* fill in the pointer to the factory in the element class. The
386 * class will not be unreffed currently.
387 * Be thread safe as there might be 2 threads creating the first instance of
388 * an element at the same moment
390 oclass = GST_ELEMENT_GET_CLASS (element);
391 if (!g_atomic_pointer_compare_and_exchange (
392 (gpointer) & oclass->elementfactory, NULL, factory))
393 gst_object_unref (factory);
395 GST_DEBUG ("created element \"%s\"", GST_PLUGIN_FEATURE_NAME (factory));
402 GST_WARNING_OBJECT (factory,
403 "loading plugin containing feature %s returned NULL!", name);
408 GST_WARNING_OBJECT (factory, "factory has no type");
409 gst_object_unref (factory);
414 GST_WARNING_OBJECT (factory, "could not create element");
415 gst_object_unref (factory);
421 * gst_element_factory_make:
422 * @factoryname: a named factory to instantiate
423 * @name: (allow-none): name of new element
425 * Create a new element of the type defined by the given element factory.
426 * If name is NULL, then the element will receive a guaranteed unique name,
427 * consisting of the element factory name and a number.
428 * If name is given, it will be given the name supplied.
430 * Returns: new #GstElement or NULL if unable to create element
433 gst_element_factory_make (const gchar * factoryname, const gchar * name)
435 GstElementFactory *factory;
438 g_return_val_if_fail (factoryname != NULL, NULL);
439 g_return_val_if_fail (gst_is_initialized (), NULL);
441 GST_LOG ("gstelementfactory: make \"%s\" \"%s\"",
442 factoryname, GST_STR_NULL (name));
444 factory = gst_element_factory_find (factoryname);
448 GST_LOG_OBJECT (factory, "found factory %p", factory);
449 element = gst_element_factory_create (factory, name);
453 gst_object_unref (factory);
459 GST_INFO ("no such element factory \"%s\"!", factoryname);
464 GST_INFO_OBJECT (factory, "couldn't create instance!");
465 gst_object_unref (factory);
471 __gst_element_factory_add_static_pad_template (GstElementFactory * factory,
472 GstStaticPadTemplate * templ)
474 g_return_if_fail (factory != NULL);
475 g_return_if_fail (templ != NULL);
477 factory->staticpadtemplates =
478 g_list_append (factory->staticpadtemplates, templ);
479 factory->numpadtemplates++;
483 * gst_element_factory_get_element_type:
484 * @factory: factory to get managed #GType from
486 * Get the #GType for elements managed by this factory. The type can
487 * only be retrieved if the element factory is loaded, which can be
488 * assured with gst_plugin_feature_load().
490 * Returns: the #GType for elements managed by this factory or 0 if
491 * the factory is not loaded.
494 gst_element_factory_get_element_type (GstElementFactory * factory)
496 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), 0);
498 return factory->type;
502 * gst_element_factory_get_longname:
503 * @factory: a #GstElementFactory
505 * Gets the longname for this factory
507 * Returns: the longname
509 G_CONST_RETURN gchar *
510 gst_element_factory_get_longname (GstElementFactory * factory)
512 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
514 return factory->details.longname;
518 * gst_element_factory_get_klass:
519 * @factory: a #GstElementFactory
521 * Gets the class for this factory.
525 G_CONST_RETURN gchar *
526 gst_element_factory_get_klass (GstElementFactory * factory)
528 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
530 return factory->details.klass;
534 * gst_element_factory_get_description:
535 * @factory: a #GstElementFactory
537 * Gets the description for this factory.
539 * Returns: the description
541 G_CONST_RETURN gchar *
542 gst_element_factory_get_description (GstElementFactory * factory)
544 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
546 return factory->details.description;
550 * gst_element_factory_get_author:
551 * @factory: a #GstElementFactory
553 * Gets the author for this factory.
555 * Returns: the author
557 G_CONST_RETURN gchar *
558 gst_element_factory_get_author (GstElementFactory * factory)
560 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
562 return factory->details.author;
565 static G_CONST_RETURN gchar *
566 gst_element_factory_get_meta_data (GstElementFactory * factory,
569 /* FIXME: do we want to support other types? */
570 return gst_structure_get_string ((GstStructure *) factory->meta_data, key);
574 * gst_element_factory_get_documentation_uri:
575 * @factory: a #GstElementFactory
577 * Gets documentation uri for this factory if set.
581 * Returns: the documentation uri
583 G_CONST_RETURN gchar *
584 gst_element_factory_get_documentation_uri (GstElementFactory * factory)
586 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
587 return gst_element_factory_get_meta_data (factory, "doc-uri");
591 * gst_element_factory_get_documentation_uri:
592 * @factory: a #GstElementFactory
594 * Gets icon name for this factory if set.
598 * Returns: the icon name
600 G_CONST_RETURN gchar *
601 gst_element_factory_get_icon_name (GstElementFactory * factory)
603 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
604 return gst_element_factory_get_meta_data (factory, "icon-name");
608 * gst_element_factory_get_num_pad_templates:
609 * @factory: a #GstElementFactory
611 * Gets the number of pad_templates in this factory.
613 * Returns: the number of pad_templates
616 gst_element_factory_get_num_pad_templates (GstElementFactory * factory)
618 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), 0);
620 return factory->numpadtemplates;
624 * __gst_element_factory_add_interface:
625 * @elementfactory: The elementfactory to add the interface to
626 * @interfacename: Name of the interface
628 * Adds the given interfacename to the list of implemented interfaces of the
632 __gst_element_factory_add_interface (GstElementFactory * elementfactory,
633 const gchar * interfacename)
635 g_return_if_fail (GST_IS_ELEMENT_FACTORY (elementfactory));
636 g_return_if_fail (interfacename != NULL);
637 g_return_if_fail (interfacename[0] != '\0'); /* no empty string */
639 elementfactory->interfaces =
640 g_list_prepend (elementfactory->interfaces, g_strdup (interfacename));
644 * gst_element_factory_get_static_pad_templates:
645 * @factory: a #GstElementFactory
647 * Gets the #GList of #GstStaticPadTemplate for this factory.
649 * Returns: the padtemplates
651 G_CONST_RETURN GList *
652 gst_element_factory_get_static_pad_templates (GstElementFactory * factory)
654 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
656 return factory->staticpadtemplates;
660 * gst_element_factory_get_uri_type:
661 * @factory: a #GstElementFactory
663 * Gets the type of URIs the element supports or #GST_URI_UNKNOWN if none.
665 * Returns: type of URIs this element supports
668 gst_element_factory_get_uri_type (GstElementFactory * factory)
670 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), GST_URI_UNKNOWN);
672 return factory->uri_type;
676 * gst_element_factory_get_uri_protocols:
677 * @factory: a #GstElementFactory
679 * Gets a NULL-terminated array of protocols this element supports or NULL if
680 * no protocols are supported. You may not change the contents of the returned
681 * array, as it is still owned by the element factory. Use g_strdupv() to
682 * make a copy of the protocol string array if you need to.
684 * Returns: the supported protocols or NULL
687 gst_element_factory_get_uri_protocols (GstElementFactory * factory)
689 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
691 return factory->uri_protocols;
695 * gst_element_factory_has_interface:
696 * @factory: a #GstElementFactory
697 * @interfacename: an interface name
699 * Check if @factory implements the interface with name @interfacename.
701 * Returns: #TRUE when @factory implement the interface.
706 gst_element_factory_has_interface (GstElementFactory * factory,
707 const gchar * interfacename)
711 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), FALSE);
713 for (walk = factory->interfaces; walk; walk = g_list_next (walk)) {
714 gchar *iname = (gchar *) walk->data;
716 if (!strcmp (iname, interfacename))
725 GstElementFactoryListType type;
731 * gst_element_factory_list_is_type:
732 * @factory: a #GstElementFactory
733 * @type: a #GstElementFactoryListType
735 * Check if @factory if of the given types.
737 * Returns: %TRUE if @factory is of @type.
742 gst_element_factory_list_is_type (GstElementFactory * factory,
743 GstElementFactoryListType type)
745 gboolean res = FALSE;
748 klass = gst_element_factory_get_klass (factory);
750 /* Filter by element type first, as soon as it matches
751 * one type, we skip all other tests */
752 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_SINK))
753 res = (strstr (klass, "Sink") != NULL);
755 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_SRC))
756 res = (strstr (klass, "Source") != NULL);
758 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_DECODER))
759 res = (strstr (klass, "Decoder") != NULL);
761 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_ENCODER))
762 res = (strstr (klass, "Encoder") != NULL);
764 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_MUXER))
765 res = (strstr (klass, "Muxer") != NULL);
767 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_DEMUXER))
768 res = (strstr (klass, "Demux") != NULL);
770 /* FIXME : We're actually parsing two Classes here... */
771 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_PARSER))
772 res = ((strstr (klass, "Parser") != NULL)
773 && (strstr (klass, "Codec") != NULL));
775 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_DEPAYLOADER))
776 res = (strstr (klass, "Depayloader") != NULL);
778 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_PAYLOADER))
779 res = (strstr (klass, "Payloader") != NULL);
781 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_FORMATTER))
782 res = (strstr (klass, "Formatter") != NULL);
784 /* Filter by media type now, we only test if it
785 * matched any of the types above. */
787 && (type & (GST_ELEMENT_FACTORY_TYPE_MEDIA_AUDIO |
788 GST_ELEMENT_FACTORY_TYPE_MEDIA_VIDEO |
789 GST_ELEMENT_FACTORY_TYPE_MEDIA_IMAGE)))
790 res = ((type & GST_ELEMENT_FACTORY_TYPE_MEDIA_AUDIO)
791 && (strstr (klass, "Audio") != NULL))
792 || ((type & GST_ELEMENT_FACTORY_TYPE_MEDIA_VIDEO)
793 && (strstr (klass, "Video") != NULL))
794 || ((type & GST_ELEMENT_FACTORY_TYPE_MEDIA_IMAGE)
795 && (strstr (klass, "Image") != NULL));
801 element_filter (GstPluginFeature * feature, FilterData * data)
805 /* we only care about element factories */
806 if (G_UNLIKELY (!GST_IS_ELEMENT_FACTORY (feature)))
809 res = (gst_plugin_feature_get_rank (feature) >= data->minrank) &&
810 gst_element_factory_list_is_type (GST_ELEMENT_FACTORY_CAST (feature),
817 * gst_element_factory_list_get_elements:
818 * @type: a #GstElementFactoryListType
819 * @minrank: Minimum rank
821 * Get a list of factories that match the given @type. Only elements
822 * with a rank greater or equal to @minrank will be returned.
823 * The list of factories is returned by decreasing rank.
825 * Returns: a #GList of #GstElementFactory elements. Use
826 * gst_plugin_feature_list_free() after usage.
831 gst_element_factory_list_get_elements (GstElementFactoryListType type,
839 data.minrank = minrank;
841 /* get the feature list using the filter */
842 result = gst_default_registry_feature_filter ((GstPluginFeatureFilter)
843 element_filter, FALSE, &data);
845 /* sort on rank and name */
846 result = g_list_sort (result, gst_plugin_feature_rank_compare_func);
852 * gst_element_factory_list_filter:
853 * @list: a #GList of #GstElementFactory to filter
855 * @direction: a #GstPadDirection to filter on
856 * @subsetonly: whether to filter on caps subsets or not.
858 * Filter out all the elementfactories in @list that can handle @caps in
859 * the given direction.
861 * If @subsetonly is %TRUE, then only the elements whose pads templates
862 * are a complete superset of @caps will be returned. Else any element
863 * whose pad templates caps can intersect with @caps will be returned.
865 * Returns: a #GList of #GstElementFactory elements that match the
866 * given requisits. Use #gst_plugin_feature_list_free after usage.
871 gst_element_factory_list_filter (GList * list,
872 const GstCaps * caps, GstPadDirection direction, gboolean subsetonly)
874 GList *result = NULL;
876 GST_DEBUG ("finding factories");
878 /* loop over all the factories */
879 for (; list; list = list->next) {
880 GstElementFactory *factory;
881 const GList *templates;
884 factory = (GstElementFactory *) list->data;
886 GST_DEBUG ("Trying %s",
887 gst_plugin_feature_get_name ((GstPluginFeature *) factory));
889 /* get the templates from the element factory */
890 templates = gst_element_factory_get_static_pad_templates (factory);
891 for (walk = (GList *) templates; walk; walk = g_list_next (walk)) {
892 GstStaticPadTemplate *templ = walk->data;
894 /* we only care about the sink templates */
895 if (templ->direction == direction) {
898 /* try to intersect the caps with the caps of the template */
899 tmpl_caps = gst_static_caps_get (&templ->static_caps);
901 /* FIXME, intersect is not the right method, we ideally want to check
902 * for a subset here */
904 /* check if the intersection is empty */
905 if ((subsetonly && gst_caps_is_subset (caps, tmpl_caps)) ||
906 (!subsetonly && gst_caps_can_intersect (caps, tmpl_caps))) {
907 /* non empty intersection, we can use this element */
908 result = g_list_prepend (result, gst_object_ref (factory));
911 gst_caps_unref (tmpl_caps);
915 return g_list_reverse (result);