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"
68 #include "glib-compat-private.h"
70 GST_DEBUG_CATEGORY_STATIC (element_factory_debug);
71 #define GST_CAT_DEFAULT element_factory_debug
73 static void gst_element_factory_finalize (GObject * object);
74 static void gst_element_factory_cleanup (GstElementFactory * factory);
76 /* static guint gst_element_factory_signals[LAST_SIGNAL] = { 0 }; */
78 /* this is defined in gstelement.c */
79 extern GQuark _gst_elementclass_factory;
83 GST_DEBUG_CATEGORY_INIT (element_factory_debug, "GST_ELEMENT_FACTORY", \
84 GST_DEBUG_BOLD | GST_DEBUG_FG_WHITE | GST_DEBUG_BG_RED, \
85 "element factories keep information about installed elements"); \
88 G_DEFINE_TYPE_WITH_CODE (GstElementFactory, gst_element_factory,
89 GST_TYPE_PLUGIN_FEATURE, _do_init);
92 gst_element_factory_class_init (GstElementFactoryClass * klass)
94 GObjectClass *gobject_class = (GObjectClass *) klass;
96 gobject_class->finalize = gst_element_factory_finalize;
100 gst_element_factory_init (GstElementFactory * factory)
102 factory->staticpadtemplates = NULL;
103 factory->numpadtemplates = 0;
105 factory->uri_type = GST_URI_UNKNOWN;
106 factory->uri_protocols = NULL;
108 factory->interfaces = NULL;
112 gst_element_factory_finalize (GObject * object)
114 GstElementFactory *factory = GST_ELEMENT_FACTORY (object);
116 gst_element_factory_cleanup (factory);
117 G_OBJECT_CLASS (gst_element_factory_parent_class)->finalize (object);
121 * gst_element_factory_find:
122 * @name: name of factory to find
124 * Search for an element factory of the given name. Refs the returned
125 * element factory; caller is responsible for unreffing.
127 * Returns: #GstElementFactory if found, NULL otherwise
130 gst_element_factory_find (const gchar * name)
132 GstPluginFeature *feature;
134 g_return_val_if_fail (name != NULL, NULL);
136 feature = gst_registry_find_feature (gst_registry_get_default (), name,
137 GST_TYPE_ELEMENT_FACTORY);
139 return GST_ELEMENT_FACTORY (feature);
141 /* this isn't an error, for instance when you query if an element factory is
143 GST_LOG ("no such element factory \"%s\"", name);
148 gst_element_factory_cleanup (GstElementFactory * factory)
152 __gst_element_details_clear (&factory->details);
153 if (factory->meta_data) {
154 gst_structure_free ((GstStructure *) factory->meta_data);
155 factory->meta_data = NULL;
158 factory->type = G_TYPE_INVALID;
161 for (item = factory->staticpadtemplates; item; item = item->next) {
162 GstStaticPadTemplate *templ = item->data;
163 GstCaps *caps = (GstCaps *) & (templ->static_caps);
165 g_free ((gchar *) templ->static_caps.string);
167 /* FIXME: this is not threadsafe */
168 if (caps->refcount == 1) {
169 GstStructure *structure;
172 for (i = 0; i < caps->structs->len; i++) {
173 structure = (GstStructure *) gst_caps_get_structure (caps, i);
174 gst_structure_set_parent_refcount (structure, NULL);
175 gst_structure_free (structure);
177 g_ptr_array_free (caps->structs, TRUE);
180 g_slice_free (GstStaticPadTemplate, templ);
182 g_list_free (factory->staticpadtemplates);
183 factory->staticpadtemplates = NULL;
184 factory->numpadtemplates = 0;
185 factory->uri_type = GST_URI_UNKNOWN;
186 if (factory->uri_protocols) {
187 g_strfreev (factory->uri_protocols);
188 factory->uri_protocols = NULL;
191 g_list_foreach (factory->interfaces, (GFunc) g_free, NULL);
192 g_list_free (factory->interfaces);
193 factory->interfaces = NULL;
197 * gst_element_register:
198 * @plugin: #GstPlugin to register the element with, or NULL for a static
199 * element (note that passing NULL only works in GStreamer 0.10.13 and later)
200 * @name: name of elements of this type
201 * @rank: rank of element (higher rank means more importance when autoplugging)
202 * @type: GType of element to register
204 * Create a new elementfactory capable of instantiating objects of the
205 * @type and add the factory to @plugin.
207 * Returns: TRUE, if the registering succeeded, FALSE on error
210 gst_element_register (GstPlugin * plugin, const gchar * name, guint rank,
213 GstPluginFeature *existing_feature;
214 GstRegistry *registry;
215 GstElementFactory *factory;
217 guint n_interfaces, i;
218 GstElementClass *klass;
221 g_return_val_if_fail (name != NULL, FALSE);
222 g_return_val_if_fail (g_type_is_a (type, GST_TYPE_ELEMENT), FALSE);
224 registry = gst_registry_get_default ();
226 /* check if feature already exists, if it exists there is no need to update it
227 * when the registry is getting updated, outdated plugins and all their
228 * features are removed and readded.
230 existing_feature = gst_registry_lookup_feature (registry, name);
231 if (existing_feature) {
232 GST_DEBUG_OBJECT (registry, "update existing feature %p (%s)",
233 existing_feature, name);
234 factory = GST_ELEMENT_FACTORY_CAST (existing_feature);
235 factory->type = type;
236 existing_feature->loaded = TRUE;
237 g_type_set_qdata (type, _gst_elementclass_factory, factory);
238 gst_object_unref (existing_feature);
243 GST_ELEMENT_FACTORY_CAST (g_object_newv (GST_TYPE_ELEMENT_FACTORY, 0,
245 gst_plugin_feature_set_name (GST_PLUGIN_FEATURE_CAST (factory), name);
246 GST_LOG_OBJECT (factory, "Created new elementfactory for type %s",
249 /* provide info needed during class structure setup */
250 g_type_set_qdata (type, _gst_elementclass_factory, factory);
251 klass = GST_ELEMENT_CLASS (g_type_class_ref (type));
252 if ((klass->details.longname == NULL) ||
253 (klass->details.klass == NULL) || (klass->details.author == NULL))
256 factory->type = type;
257 __gst_element_details_copy (&factory->details, &klass->details);
258 if (klass->meta_data) {
259 factory->meta_data = gst_structure_copy ((GstStructure *) klass->meta_data);
261 factory->meta_data = NULL;
263 for (item = klass->padtemplates; item; item = item->next) {
264 GstPadTemplate *templ = item->data;
265 GstStaticPadTemplate *newt;
267 newt = g_slice_new (GstStaticPadTemplate);
268 newt->name_template = g_intern_string (templ->name_template);
269 newt->direction = templ->direction;
270 newt->presence = templ->presence;
271 newt->static_caps.caps.refcount = 0;
272 newt->static_caps.string = gst_caps_to_string (templ->caps);
273 factory->staticpadtemplates =
274 g_list_append (factory->staticpadtemplates, newt);
276 factory->numpadtemplates = klass->numpadtemplates;
278 /* special stuff for URI handling */
279 if (g_type_is_a (type, GST_TYPE_URI_HANDLER)) {
280 GstURIHandlerInterface *iface = (GstURIHandlerInterface *)
281 g_type_interface_peek (klass, GST_TYPE_URI_HANDLER);
283 if (!iface || (!iface->get_type && !iface->get_type_full) ||
284 (!iface->get_protocols && !iface->get_protocols_full))
287 factory->uri_type = iface->get_type ();
288 else if (iface->get_type_full)
289 factory->uri_type = iface->get_type_full (factory->type);
290 if (!GST_URI_TYPE_IS_VALID (factory->uri_type))
292 if (iface->get_protocols)
293 factory->uri_protocols = g_strdupv (iface->get_protocols ());
294 else if (iface->get_protocols_full)
295 factory->uri_protocols = iface->get_protocols_full (factory->type);
296 if (!factory->uri_protocols)
300 interfaces = g_type_interfaces (type, &n_interfaces);
301 for (i = 0; i < n_interfaces; i++) {
302 __gst_element_factory_add_interface (factory, g_type_name (interfaces[i]));
306 if (plugin && plugin->desc.name) {
307 GST_PLUGIN_FEATURE_CAST (factory)->plugin_name = plugin->desc.name;
309 GST_PLUGIN_FEATURE_CAST (factory)->plugin_name = "NULL";
311 gst_plugin_feature_set_rank (GST_PLUGIN_FEATURE_CAST (factory), rank);
312 GST_PLUGIN_FEATURE_CAST (factory)->loaded = TRUE;
314 gst_registry_add_feature (registry, GST_PLUGIN_FEATURE_CAST (factory));
321 GST_WARNING_OBJECT (factory, "error with uri handler!");
322 gst_element_factory_cleanup (factory);
328 GST_WARNING_OBJECT (factory,
329 "The GstElementDetails don't seem to have been set properly");
330 gst_element_factory_cleanup (factory);
336 * gst_element_factory_create:
337 * @factory: factory to instantiate
338 * @name: name of new element
340 * Create a new element of the type defined by the given elementfactory.
341 * It will be given the name supplied, since all elements require a name as
342 * their first argument.
344 * Returns: new #GstElement or NULL if the element couldn't be created
347 gst_element_factory_create (GstElementFactory * factory, const gchar * name)
350 GstElementClass *oclass;
351 GstElementFactory *newfactory;
353 g_return_val_if_fail (factory != NULL, NULL);
356 GST_ELEMENT_FACTORY (gst_plugin_feature_load (GST_PLUGIN_FEATURE
359 if (newfactory == NULL)
362 factory = newfactory;
365 GST_INFO ("creating element \"%s\" named \"%s\"",
366 GST_PLUGIN_FEATURE_NAME (factory), GST_STR_NULL (name));
368 GST_INFO ("creating element \"%s\"", GST_PLUGIN_FEATURE_NAME (factory));
370 if (factory->type == 0)
373 /* create an instance of the element, cast so we don't assert on NULL
374 * also set name as early as we can
378 GST_ELEMENT_CAST (g_object_new (factory->type, "name", name, NULL));
380 element = GST_ELEMENT_CAST (g_object_newv (factory->type, 0, NULL));
381 if (G_UNLIKELY (element == NULL))
384 /* fill in the pointer to the factory in the element class. The
385 * class will not be unreffed currently.
386 * Be thread safe as there might be 2 threads creating the first instance of
387 * an element at the same moment
389 oclass = GST_ELEMENT_GET_CLASS (element);
390 if (!g_atomic_pointer_compare_and_exchange (
391 (gpointer) & oclass->elementfactory, NULL, factory))
392 gst_object_unref (factory);
394 GST_DEBUG ("created element \"%s\"", GST_PLUGIN_FEATURE_NAME (factory));
401 GST_WARNING_OBJECT (factory,
402 "loading plugin containing feature %s returned NULL!", name);
407 GST_WARNING_OBJECT (factory, "factory has no type");
408 gst_object_unref (factory);
413 GST_WARNING_OBJECT (factory, "could not create element");
414 gst_object_unref (factory);
420 * gst_element_factory_make:
421 * @factoryname: a named factory to instantiate
422 * @name: (allow-none): name of new element
424 * Create a new element of the type defined by the given element factory.
425 * If name is NULL, then the element will receive a guaranteed unique name,
426 * consisting of the element factory name and a number.
427 * If name is given, it will be given the name supplied.
429 * Returns: new #GstElement or NULL if unable to create element
432 gst_element_factory_make (const gchar * factoryname, const gchar * name)
434 GstElementFactory *factory;
437 g_return_val_if_fail (factoryname != NULL, NULL);
439 GST_LOG ("gstelementfactory: make \"%s\" \"%s\"",
440 factoryname, GST_STR_NULL (name));
442 factory = gst_element_factory_find (factoryname);
446 GST_LOG_OBJECT (factory, "found factory %p", factory);
447 element = gst_element_factory_create (factory, name);
451 gst_object_unref (factory);
457 GST_INFO ("no such element factory \"%s\"!", factoryname);
462 GST_INFO_OBJECT (factory, "couldn't create instance!");
463 gst_object_unref (factory);
469 __gst_element_factory_add_static_pad_template (GstElementFactory * factory,
470 GstStaticPadTemplate * templ)
472 g_return_if_fail (factory != NULL);
473 g_return_if_fail (templ != NULL);
475 factory->staticpadtemplates =
476 g_list_append (factory->staticpadtemplates, templ);
477 factory->numpadtemplates++;
481 * gst_element_factory_get_element_type:
482 * @factory: factory to get managed #GType from
484 * Get the #GType for elements managed by this factory. The type can
485 * only be retrieved if the element factory is loaded, which can be
486 * assured with gst_plugin_feature_load().
488 * Returns: the #GType for elements managed by this factory or 0 if
489 * the factory is not loaded.
492 gst_element_factory_get_element_type (GstElementFactory * factory)
494 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), 0);
496 return factory->type;
500 * gst_element_factory_get_longname:
501 * @factory: a #GstElementFactory
503 * Gets the longname for this factory
505 * Returns: the longname
507 G_CONST_RETURN gchar *
508 gst_element_factory_get_longname (GstElementFactory * factory)
510 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
512 return factory->details.longname;
516 * gst_element_factory_get_klass:
517 * @factory: a #GstElementFactory
519 * Gets the class for this factory.
523 G_CONST_RETURN gchar *
524 gst_element_factory_get_klass (GstElementFactory * factory)
526 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
528 return factory->details.klass;
532 * gst_element_factory_get_description:
533 * @factory: a #GstElementFactory
535 * Gets the description for this factory.
537 * Returns: the description
539 G_CONST_RETURN gchar *
540 gst_element_factory_get_description (GstElementFactory * factory)
542 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
544 return factory->details.description;
548 * gst_element_factory_get_author:
549 * @factory: a #GstElementFactory
551 * Gets the author for this factory.
553 * Returns: the author
555 G_CONST_RETURN gchar *
556 gst_element_factory_get_author (GstElementFactory * factory)
558 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
560 return factory->details.author;
563 static G_CONST_RETURN gchar *
564 gst_element_factory_get_meta_data (GstElementFactory * factory,
567 /* FIXME: do we want to support other types? */
568 return gst_structure_get_string ((GstStructure *) factory->meta_data, key);
572 * gst_element_factory_get_documentation_uri:
573 * @factory: a #GstElementFactory
575 * Gets documentation uri for this factory if set.
579 * Returns: the documentation uri
581 G_CONST_RETURN gchar *
582 gst_element_factory_get_documentation_uri (GstElementFactory * factory)
584 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
585 return gst_element_factory_get_meta_data (factory, "doc-uri");
589 * gst_element_factory_get_documentation_uri:
590 * @factory: a #GstElementFactory
592 * Gets icon name for this factory if set.
596 * Returns: the icon name
598 G_CONST_RETURN gchar *
599 gst_element_factory_get_icon_name (GstElementFactory * factory)
601 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
602 return gst_element_factory_get_meta_data (factory, "icon-name");
606 * gst_element_factory_get_num_pad_templates:
607 * @factory: a #GstElementFactory
609 * Gets the number of pad_templates in this factory.
611 * Returns: the number of pad_templates
614 gst_element_factory_get_num_pad_templates (GstElementFactory * factory)
616 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), 0);
618 return factory->numpadtemplates;
622 * __gst_element_factory_add_interface:
623 * @elementfactory: The elementfactory to add the interface to
624 * @interfacename: Name of the interface
626 * Adds the given interfacename to the list of implemented interfaces of the
630 __gst_element_factory_add_interface (GstElementFactory * elementfactory,
631 const gchar * interfacename)
633 g_return_if_fail (GST_IS_ELEMENT_FACTORY (elementfactory));
634 g_return_if_fail (interfacename != NULL);
635 g_return_if_fail (interfacename[0] != '\0'); /* no empty string */
637 elementfactory->interfaces =
638 g_list_prepend (elementfactory->interfaces, g_strdup (interfacename));
642 * gst_element_factory_get_static_pad_templates:
643 * @factory: a #GstElementFactory
645 * Gets the #GList of #GstStaticPadTemplate for this factory.
647 * Returns: the padtemplates
649 G_CONST_RETURN GList *
650 gst_element_factory_get_static_pad_templates (GstElementFactory * factory)
652 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
654 return factory->staticpadtemplates;
658 * gst_element_factory_get_uri_type:
659 * @factory: a #GstElementFactory
661 * Gets the type of URIs the element supports or #GST_URI_UNKNOWN if none.
663 * Returns: type of URIs this element supports
666 gst_element_factory_get_uri_type (GstElementFactory * factory)
668 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), GST_URI_UNKNOWN);
670 return factory->uri_type;
674 * gst_element_factory_get_uri_protocols:
675 * @factory: a #GstElementFactory
677 * Gets a NULL-terminated array of protocols this element supports or NULL if
678 * no protocols are supported. You may not change the contents of the returned
679 * array, as it is still owned by the element factory. Use g_strdupv() to
680 * make a copy of the protocol string array if you need to.
682 * Returns: the supported protocols or NULL
685 gst_element_factory_get_uri_protocols (GstElementFactory * factory)
687 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
689 return factory->uri_protocols;
693 * gst_element_factory_has_interface:
694 * @factory: a #GstElementFactory
695 * @interfacename: an interface name
697 * Check if @factory implements the interface with name @interfacename.
699 * Returns: #TRUE when @factory implement the interface.
704 gst_element_factory_has_interface (GstElementFactory * factory,
705 const gchar * interfacename)
709 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), FALSE);
711 for (walk = factory->interfaces; walk; walk = g_list_next (walk)) {
712 gchar *iname = (gchar *) walk->data;
714 if (!strcmp (iname, interfacename))
723 GstElementFactoryListType type;
729 * gst_element_factory_list_is_type:
730 * @factory: a #GstElementFactory
731 * @type: a #GstElementFactoryListType
733 * Check if @factory if of the given types.
735 * Returns: %TRUE if @factory is of @type.
740 gst_element_factory_list_is_type (GstElementFactory * factory,
741 GstElementFactoryListType type)
743 gboolean res = FALSE;
746 klass = gst_element_factory_get_klass (factory);
748 /* Filter by element type first, as soon as it matches
749 * one type, we skip all other tests */
750 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_SINK))
751 res = (strstr (klass, "Sink") != NULL);
753 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_SRC))
754 res = (strstr (klass, "Source") != NULL);
756 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_DECODER))
757 res = (strstr (klass, "Decoder") != NULL);
759 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_ENCODER))
760 res = (strstr (klass, "Encoder") != NULL);
762 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_MUXER))
763 res = (strstr (klass, "Muxer") != NULL);
765 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_DEMUXER))
766 res = (strstr (klass, "Demux") != NULL);
768 /* FIXME : We're actually parsing two Classes here... */
769 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_PARSER))
770 res = ((strstr (klass, "Parser") != NULL)
771 && (strstr (klass, "Codec") != NULL));
773 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_DEPAYLOADER))
774 res = (strstr (klass, "Depayloader") != NULL);
776 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_PAYLOADER))
777 res = (strstr (klass, "Payloader") != NULL);
779 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_FORMATTER))
780 res = (strstr (klass, "Formatter") != NULL);
782 /* Filter by media type now, we only test if it
783 * matched any of the types above. */
785 && (type & (GST_ELEMENT_FACTORY_TYPE_MEDIA_AUDIO |
786 GST_ELEMENT_FACTORY_TYPE_MEDIA_VIDEO |
787 GST_ELEMENT_FACTORY_TYPE_MEDIA_IMAGE)))
788 res = ((type & GST_ELEMENT_FACTORY_TYPE_MEDIA_AUDIO)
789 && (strstr (klass, "Audio") != NULL))
790 || ((type & GST_ELEMENT_FACTORY_TYPE_MEDIA_VIDEO)
791 && (strstr (klass, "Video") != NULL))
792 || ((type & GST_ELEMENT_FACTORY_TYPE_MEDIA_IMAGE)
793 && (strstr (klass, "Image") != NULL));
799 element_filter (GstPluginFeature * feature, FilterData * data)
803 /* we only care about element factories */
804 if (G_UNLIKELY (!GST_IS_ELEMENT_FACTORY (feature)))
807 res = (gst_plugin_feature_get_rank (feature) >= data->minrank) &&
808 gst_element_factory_list_is_type (GST_ELEMENT_FACTORY_CAST (feature),
815 * gst_element_factory_list_get_elements:
816 * @type: a #GstElementFactoryListType
817 * @minrank: Minimum rank
819 * Get a list of factories that match the given @type. Only elements
820 * with a rank greater or equal to @minrank will be returned.
821 * The list of factories is returned by decreasing rank.
823 * Returns: a #GList of #GstElementFactory elements. Use
824 * gst_plugin_feature_list_free() after usage.
829 gst_element_factory_list_get_elements (GstElementFactoryListType type,
837 data.minrank = minrank;
839 /* get the feature list using the filter */
840 result = gst_default_registry_feature_filter ((GstPluginFeatureFilter)
841 element_filter, FALSE, &data);
843 /* sort on rank and name */
844 result = g_list_sort (result, gst_plugin_feature_rank_compare_func);
850 * gst_element_factory_list_filter:
851 * @list: a #GList of #GstElementFactory to filter
853 * @direction: a #GstPadDirection to filter on
854 * @subsetonly: whether to filter on caps subsets or not.
856 * Filter out all the elementfactories in @list that can handle @caps in
857 * the given direction.
859 * If @subsetonly is %TRUE, then only the elements whose pads templates
860 * are a complete superset of @caps will be returned. Else any element
861 * whose pad templates caps can intersect with @caps will be returned.
863 * Returns: a #GList of #GstElementFactory elements that match the
864 * given requisits. Use #gst_plugin_feature_list_free after usage.
869 gst_element_factory_list_filter (GList * list,
870 const GstCaps * caps, GstPadDirection direction, gboolean subsetonly)
872 GList *result = NULL;
874 GST_DEBUG ("finding factories");
876 /* loop over all the factories */
877 for (; list; list = list->next) {
878 GstElementFactory *factory;
879 const GList *templates;
882 factory = (GstElementFactory *) list->data;
884 GST_DEBUG ("Trying %s",
885 gst_plugin_feature_get_name ((GstPluginFeature *) factory));
887 /* get the templates from the element factory */
888 templates = gst_element_factory_get_static_pad_templates (factory);
889 for (walk = (GList *) templates; walk; walk = g_list_next (walk)) {
890 GstStaticPadTemplate *templ = walk->data;
892 /* we only care about the sink templates */
893 if (templ->direction == direction) {
896 /* try to intersect the caps with the caps of the template */
897 tmpl_caps = gst_static_caps_get (&templ->static_caps);
899 /* FIXME, intersect is not the right method, we ideally want to check
900 * for a subset here */
902 /* check if the intersection is empty */
903 if ((subsetonly && gst_caps_is_subset (caps, tmpl_caps)) ||
904 (!subsetonly && gst_caps_can_intersect (caps, tmpl_caps))) {
905 /* non empty intersection, we can use this element */
906 result = g_list_prepend (result, gst_object_ref (factory));
909 gst_caps_unref (tmpl_caps);
913 return g_list_reverse (result);