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 GstPluginFeatureClass *parent_class = NULL;
78 /* static guint gst_element_factory_signals[LAST_SIGNAL] = { 0 }; */
80 /* this is defined in gstelement.c */
81 extern GQuark _gst_elementclass_factory;
85 GST_DEBUG_CATEGORY_INIT (element_factory_debug, "GST_ELEMENT_FACTORY", \
86 GST_DEBUG_BOLD | GST_DEBUG_FG_WHITE | GST_DEBUG_BG_RED, \
87 "element factories keep information about installed elements"); \
90 G_DEFINE_TYPE_WITH_CODE (GstElementFactory, gst_element_factory,
91 GST_TYPE_PLUGIN_FEATURE, _do_init);
94 gst_element_factory_class_init (GstElementFactoryClass * klass)
96 GObjectClass *gobject_class = (GObjectClass *) klass;
98 parent_class = g_type_class_peek_parent (klass);
100 gobject_class->finalize = gst_element_factory_finalize;
104 gst_element_factory_init (GstElementFactory * factory)
106 factory->staticpadtemplates = NULL;
107 factory->numpadtemplates = 0;
109 factory->uri_type = GST_URI_UNKNOWN;
110 factory->uri_protocols = NULL;
112 factory->interfaces = NULL;
116 gst_element_factory_finalize (GObject * object)
118 GstElementFactory *factory = GST_ELEMENT_FACTORY (object);
120 gst_element_factory_cleanup (factory);
121 G_OBJECT_CLASS (parent_class)->finalize (object);
125 * gst_element_factory_find:
126 * @name: name of factory to find
128 * Search for an element factory of the given name. Refs the returned
129 * element factory; caller is responsible for unreffing.
131 * Returns: #GstElementFactory if found, NULL otherwise
134 gst_element_factory_find (const gchar * name)
136 GstPluginFeature *feature;
138 g_return_val_if_fail (name != NULL, NULL);
140 feature = gst_registry_find_feature (gst_registry_get_default (), name,
141 GST_TYPE_ELEMENT_FACTORY);
143 return GST_ELEMENT_FACTORY (feature);
145 /* this isn't an error, for instance when you query if an element factory is
147 GST_LOG ("no such element factory \"%s\"", name);
152 gst_element_factory_cleanup (GstElementFactory * factory)
156 __gst_element_details_clear (&factory->details);
157 if (factory->meta_data) {
158 gst_structure_free ((GstStructure *) factory->meta_data);
159 factory->meta_data = NULL;
162 factory->type = G_TYPE_INVALID;
165 for (item = factory->staticpadtemplates; item; item = item->next) {
166 GstStaticPadTemplate *templ = item->data;
167 GstCaps *caps = (GstCaps *) & (templ->static_caps);
169 g_free ((gchar *) templ->static_caps.string);
171 /* FIXME: this is not threadsafe */
172 if (caps->refcount == 1) {
173 GstStructure *structure;
176 for (i = 0; i < caps->structs->len; i++) {
177 structure = (GstStructure *) gst_caps_get_structure (caps, i);
178 gst_structure_set_parent_refcount (structure, NULL);
179 gst_structure_free (structure);
181 g_ptr_array_free (caps->structs, TRUE);
184 g_slice_free (GstStaticPadTemplate, templ);
186 g_list_free (factory->staticpadtemplates);
187 factory->staticpadtemplates = NULL;
188 factory->numpadtemplates = 0;
189 factory->uri_type = GST_URI_UNKNOWN;
190 if (factory->uri_protocols) {
191 g_strfreev (factory->uri_protocols);
192 factory->uri_protocols = NULL;
195 g_list_foreach (factory->interfaces, (GFunc) g_free, NULL);
196 g_list_free (factory->interfaces);
197 factory->interfaces = NULL;
201 * gst_element_register:
202 * @plugin: #GstPlugin to register the element with, or NULL for a static
203 * element (note that passing NULL only works in GStreamer 0.10.13 and later)
204 * @name: name of elements of this type
205 * @rank: rank of element (higher rank means more importance when autoplugging)
206 * @type: GType of element to register
208 * Create a new elementfactory capable of instantiating objects of the
209 * @type and add the factory to @plugin.
211 * Returns: TRUE, if the registering succeeded, FALSE on error
214 gst_element_register (GstPlugin * plugin, const gchar * name, guint rank,
217 GstPluginFeature *existing_feature;
218 GstRegistry *registry;
219 GstElementFactory *factory;
221 guint n_interfaces, i;
222 GstElementClass *klass;
225 g_return_val_if_fail (name != NULL, FALSE);
226 g_return_val_if_fail (g_type_is_a (type, GST_TYPE_ELEMENT), FALSE);
228 registry = gst_registry_get_default ();
230 /* check if feature already exists, if it exists there is no need to update it
231 * when the registry is getting updated, outdated plugins and all their
232 * features are removed and readded.
234 existing_feature = gst_registry_lookup_feature (registry, name);
235 if (existing_feature) {
236 GST_DEBUG_OBJECT (registry, "update existing feature %p (%s)",
237 existing_feature, name);
238 factory = GST_ELEMENT_FACTORY_CAST (existing_feature);
239 factory->type = type;
240 existing_feature->loaded = TRUE;
241 g_type_set_qdata (type, _gst_elementclass_factory, factory);
242 gst_object_unref (existing_feature);
247 GST_ELEMENT_FACTORY_CAST (g_object_newv (GST_TYPE_ELEMENT_FACTORY, 0,
249 gst_plugin_feature_set_name (GST_PLUGIN_FEATURE_CAST (factory), name);
250 GST_LOG_OBJECT (factory, "Created new elementfactory for type %s",
253 /* provide info needed during class structure setup */
254 g_type_set_qdata (type, _gst_elementclass_factory, factory);
255 klass = GST_ELEMENT_CLASS (g_type_class_ref (type));
256 if ((klass->details.longname == NULL) ||
257 (klass->details.klass == NULL) || (klass->details.author == NULL))
260 factory->type = type;
261 __gst_element_details_copy (&factory->details, &klass->details);
262 if (klass->meta_data) {
263 factory->meta_data = gst_structure_copy ((GstStructure *) klass->meta_data);
265 factory->meta_data = NULL;
267 for (item = klass->padtemplates; item; item = item->next) {
268 GstPadTemplate *templ = item->data;
269 GstStaticPadTemplate *newt;
271 newt = g_slice_new (GstStaticPadTemplate);
272 newt->name_template = g_intern_string (templ->name_template);
273 newt->direction = templ->direction;
274 newt->presence = templ->presence;
275 newt->static_caps.caps.refcount = 0;
276 newt->static_caps.string = gst_caps_to_string (templ->caps);
277 factory->staticpadtemplates =
278 g_list_append (factory->staticpadtemplates, newt);
280 factory->numpadtemplates = klass->numpadtemplates;
282 /* special stuff for URI handling */
283 if (g_type_is_a (type, GST_TYPE_URI_HANDLER)) {
284 GstURIHandlerInterface *iface = (GstURIHandlerInterface *)
285 g_type_interface_peek (klass, GST_TYPE_URI_HANDLER);
287 if (!iface || (!iface->get_type && !iface->get_type_full) ||
288 (!iface->get_protocols && !iface->get_protocols_full))
291 factory->uri_type = iface->get_type ();
292 else if (iface->get_type_full)
293 factory->uri_type = iface->get_type_full (factory->type);
294 if (!GST_URI_TYPE_IS_VALID (factory->uri_type))
296 if (iface->get_protocols)
297 factory->uri_protocols = g_strdupv (iface->get_protocols ());
298 else if (iface->get_protocols_full)
299 factory->uri_protocols = iface->get_protocols_full (factory->type);
300 if (!factory->uri_protocols)
304 interfaces = g_type_interfaces (type, &n_interfaces);
305 for (i = 0; i < n_interfaces; i++) {
306 __gst_element_factory_add_interface (factory, g_type_name (interfaces[i]));
310 if (plugin && plugin->desc.name) {
311 GST_PLUGIN_FEATURE_CAST (factory)->plugin_name = plugin->desc.name;
313 GST_PLUGIN_FEATURE_CAST (factory)->plugin_name = "NULL";
315 gst_plugin_feature_set_rank (GST_PLUGIN_FEATURE_CAST (factory), rank);
316 GST_PLUGIN_FEATURE_CAST (factory)->loaded = TRUE;
318 gst_registry_add_feature (registry, GST_PLUGIN_FEATURE_CAST (factory));
325 GST_WARNING_OBJECT (factory, "error with uri handler!");
326 gst_element_factory_cleanup (factory);
332 GST_WARNING_OBJECT (factory,
333 "The GstElementDetails don't seem to have been set properly");
334 gst_element_factory_cleanup (factory);
340 * gst_element_factory_create:
341 * @factory: factory to instantiate
342 * @name: name of new element
344 * Create a new element of the type defined by the given elementfactory.
345 * It will be given the name supplied, since all elements require a name as
346 * their first argument.
348 * Returns: new #GstElement or NULL if the element couldn't be created
351 gst_element_factory_create (GstElementFactory * factory, const gchar * name)
354 GstElementClass *oclass;
355 GstElementFactory *newfactory;
357 g_return_val_if_fail (factory != NULL, NULL);
360 GST_ELEMENT_FACTORY (gst_plugin_feature_load (GST_PLUGIN_FEATURE
363 if (newfactory == NULL)
366 factory = newfactory;
369 GST_INFO ("creating element \"%s\" named \"%s\"",
370 GST_PLUGIN_FEATURE_NAME (factory), GST_STR_NULL (name));
372 GST_INFO ("creating element \"%s\"", GST_PLUGIN_FEATURE_NAME (factory));
374 if (factory->type == 0)
377 /* create an instance of the element, cast so we don't assert on NULL
378 * also set name as early as we can
382 GST_ELEMENT_CAST (g_object_new (factory->type, "name", name, NULL));
384 element = GST_ELEMENT_CAST (g_object_newv (factory->type, 0, NULL));
385 if (G_UNLIKELY (element == NULL))
388 /* fill in the pointer to the factory in the element class. The
389 * class will not be unreffed currently.
390 * Be thread safe as there might be 2 threads creating the first instance of
391 * an element at the same moment
393 oclass = GST_ELEMENT_GET_CLASS (element);
394 if (!g_atomic_pointer_compare_and_exchange (
395 (gpointer) & oclass->elementfactory, NULL, factory))
396 gst_object_unref (factory);
398 GST_DEBUG ("created element \"%s\"", GST_PLUGIN_FEATURE_NAME (factory));
405 GST_WARNING_OBJECT (factory,
406 "loading plugin containing feature %s returned NULL!", name);
411 GST_WARNING_OBJECT (factory, "factory has no type");
412 gst_object_unref (factory);
417 GST_WARNING_OBJECT (factory, "could not create element");
418 gst_object_unref (factory);
424 * gst_element_factory_make:
425 * @factoryname: a named factory to instantiate
426 * @name: (allow-none): name of new element
428 * Create a new element of the type defined by the given element factory.
429 * If name is NULL, then the element will receive a guaranteed unique name,
430 * consisting of the element factory name and a number.
431 * If name is given, it will be given the name supplied.
433 * Returns: new #GstElement or NULL if unable to create element
436 gst_element_factory_make (const gchar * factoryname, const gchar * name)
438 GstElementFactory *factory;
441 g_return_val_if_fail (factoryname != NULL, NULL);
443 GST_LOG ("gstelementfactory: make \"%s\" \"%s\"",
444 factoryname, GST_STR_NULL (name));
446 factory = gst_element_factory_find (factoryname);
450 GST_LOG_OBJECT (factory, "found factory %p", factory);
451 element = gst_element_factory_create (factory, name);
455 gst_object_unref (factory);
461 GST_INFO ("no such element factory \"%s\"!", factoryname);
466 GST_INFO_OBJECT (factory, "couldn't create instance!");
467 gst_object_unref (factory);
473 __gst_element_factory_add_static_pad_template (GstElementFactory * factory,
474 GstStaticPadTemplate * templ)
476 g_return_if_fail (factory != NULL);
477 g_return_if_fail (templ != NULL);
479 factory->staticpadtemplates =
480 g_list_append (factory->staticpadtemplates, templ);
481 factory->numpadtemplates++;
485 * gst_element_factory_get_element_type:
486 * @factory: factory to get managed #GType from
488 * Get the #GType for elements managed by this factory. The type can
489 * only be retrieved if the element factory is loaded, which can be
490 * assured with gst_plugin_feature_load().
492 * Returns: the #GType for elements managed by this factory or 0 if
493 * the factory is not loaded.
496 gst_element_factory_get_element_type (GstElementFactory * factory)
498 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), 0);
500 return factory->type;
504 * gst_element_factory_get_longname:
505 * @factory: a #GstElementFactory
507 * Gets the longname for this factory
509 * Returns: the longname
511 G_CONST_RETURN gchar *
512 gst_element_factory_get_longname (GstElementFactory * factory)
514 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
516 return factory->details.longname;
520 * gst_element_factory_get_klass:
521 * @factory: a #GstElementFactory
523 * Gets the class for this factory.
527 G_CONST_RETURN gchar *
528 gst_element_factory_get_klass (GstElementFactory * factory)
530 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
532 return factory->details.klass;
536 * gst_element_factory_get_description:
537 * @factory: a #GstElementFactory
539 * Gets the description for this factory.
541 * Returns: the description
543 G_CONST_RETURN gchar *
544 gst_element_factory_get_description (GstElementFactory * factory)
546 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
548 return factory->details.description;
552 * gst_element_factory_get_author:
553 * @factory: a #GstElementFactory
555 * Gets the author for this factory.
557 * Returns: the author
559 G_CONST_RETURN gchar *
560 gst_element_factory_get_author (GstElementFactory * factory)
562 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
564 return factory->details.author;
567 static G_CONST_RETURN gchar *
568 gst_element_factory_get_meta_data (GstElementFactory * factory,
571 /* FIXME: do we want to support other types? */
572 return gst_structure_get_string ((GstStructure *) factory->meta_data, key);
576 * gst_element_factory_get_documentation_uri:
577 * @factory: a #GstElementFactory
579 * Gets documentation uri for this factory if set.
583 * Returns: the documentation uri
585 G_CONST_RETURN gchar *
586 gst_element_factory_get_documentation_uri (GstElementFactory * factory)
588 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
589 return gst_element_factory_get_meta_data (factory, "doc-uri");
593 * gst_element_factory_get_documentation_uri:
594 * @factory: a #GstElementFactory
596 * Gets icon name for this factory if set.
600 * Returns: the icon name
602 G_CONST_RETURN gchar *
603 gst_element_factory_get_icon_name (GstElementFactory * factory)
605 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
606 return gst_element_factory_get_meta_data (factory, "icon-name");
610 * gst_element_factory_get_num_pad_templates:
611 * @factory: a #GstElementFactory
613 * Gets the number of pad_templates in this factory.
615 * Returns: the number of pad_templates
618 gst_element_factory_get_num_pad_templates (GstElementFactory * factory)
620 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), 0);
622 return factory->numpadtemplates;
626 * __gst_element_factory_add_interface:
627 * @elementfactory: The elementfactory to add the interface to
628 * @interfacename: Name of the interface
630 * Adds the given interfacename to the list of implemented interfaces of the
634 __gst_element_factory_add_interface (GstElementFactory * elementfactory,
635 const gchar * interfacename)
637 g_return_if_fail (GST_IS_ELEMENT_FACTORY (elementfactory));
638 g_return_if_fail (interfacename != NULL);
639 g_return_if_fail (interfacename[0] != '\0'); /* no empty string */
641 elementfactory->interfaces =
642 g_list_prepend (elementfactory->interfaces, g_strdup (interfacename));
646 * gst_element_factory_get_static_pad_templates:
647 * @factory: a #GstElementFactory
649 * Gets the #GList of #GstStaticPadTemplate for this factory.
651 * Returns: the padtemplates
653 G_CONST_RETURN GList *
654 gst_element_factory_get_static_pad_templates (GstElementFactory * factory)
656 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
658 return factory->staticpadtemplates;
662 * gst_element_factory_get_uri_type:
663 * @factory: a #GstElementFactory
665 * Gets the type of URIs the element supports or #GST_URI_UNKNOWN if none.
667 * Returns: type of URIs this element supports
670 gst_element_factory_get_uri_type (GstElementFactory * factory)
672 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), GST_URI_UNKNOWN);
674 return factory->uri_type;
678 * gst_element_factory_get_uri_protocols:
679 * @factory: a #GstElementFactory
681 * Gets a NULL-terminated array of protocols this element supports or NULL if
682 * no protocols are supported. You may not change the contents of the returned
683 * array, as it is still owned by the element factory. Use g_strdupv() to
684 * make a copy of the protocol string array if you need to.
686 * Returns: the supported protocols or NULL
689 gst_element_factory_get_uri_protocols (GstElementFactory * factory)
691 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
693 return factory->uri_protocols;
697 * gst_element_factory_has_interface:
698 * @factory: a #GstElementFactory
699 * @interfacename: an interface name
701 * Check if @factory implements the interface with name @interfacename.
703 * Returns: #TRUE when @factory implement the interface.
708 gst_element_factory_has_interface (GstElementFactory * factory,
709 const gchar * interfacename)
713 g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), FALSE);
715 for (walk = factory->interfaces; walk; walk = g_list_next (walk)) {
716 gchar *iname = (gchar *) walk->data;
718 if (!strcmp (iname, interfacename))
727 GstElementFactoryListType type;
733 * gst_element_factory_list_is_type:
734 * @factory: a #GstElementFactory
735 * @type: a #GstElementFactoryListType
737 * Check if @factory if of the given types.
739 * Returns: %TRUE if @factory is of @type.
744 gst_element_factory_list_is_type (GstElementFactory * factory,
745 GstElementFactoryListType type)
747 gboolean res = FALSE;
750 klass = gst_element_factory_get_klass (factory);
752 /* Filter by element type first, as soon as it matches
753 * one type, we skip all other tests */
754 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_SINK))
755 res = (strstr (klass, "Sink") != NULL);
757 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_SRC))
758 res = (strstr (klass, "Source") != NULL);
760 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_DECODER))
761 res = (strstr (klass, "Decoder") != NULL);
763 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_ENCODER))
764 res = (strstr (klass, "Encoder") != NULL);
766 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_MUXER))
767 res = (strstr (klass, "Muxer") != NULL);
769 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_DEMUXER))
770 res = (strstr (klass, "Demux") != NULL);
772 /* FIXME : We're actually parsing two Classes here... */
773 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_PARSER))
774 res = ((strstr (klass, "Parser") != NULL)
775 && (strstr (klass, "Codec") != NULL));
777 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_DEPAYLOADER))
778 res = (strstr (klass, "Depayloader") != NULL);
780 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_PAYLOADER))
781 res = (strstr (klass, "Payloader") != NULL);
783 if (!res && (type & GST_ELEMENT_FACTORY_TYPE_FORMATTER))
784 res = (strstr (klass, "Formatter") != NULL);
786 /* Filter by media type now, we only test if it
787 * matched any of the types above. */
789 && (type & (GST_ELEMENT_FACTORY_TYPE_MEDIA_AUDIO |
790 GST_ELEMENT_FACTORY_TYPE_MEDIA_VIDEO |
791 GST_ELEMENT_FACTORY_TYPE_MEDIA_IMAGE)))
792 res = ((type & GST_ELEMENT_FACTORY_TYPE_MEDIA_AUDIO)
793 && (strstr (klass, "Audio") != NULL))
794 || ((type & GST_ELEMENT_FACTORY_TYPE_MEDIA_VIDEO)
795 && (strstr (klass, "Video") != NULL))
796 || ((type & GST_ELEMENT_FACTORY_TYPE_MEDIA_IMAGE)
797 && (strstr (klass, "Image") != NULL));
803 element_filter (GstPluginFeature * feature, FilterData * data)
807 /* we only care about element factories */
808 if (G_UNLIKELY (!GST_IS_ELEMENT_FACTORY (feature)))
811 res = (gst_plugin_feature_get_rank (feature) >= data->minrank) &&
812 gst_element_factory_list_is_type (GST_ELEMENT_FACTORY_CAST (feature),
819 * gst_element_factory_list_get_elements:
820 * @type: a #GstElementFactoryListType
821 * @minrank: Minimum rank
823 * Get a list of factories that match the given @type. Only elements
824 * with a rank greater or equal to @minrank will be returned.
825 * The list of factories is returned by decreasing rank.
827 * Returns: a #GList of #GstElementFactory elements. Use
828 * gst_plugin_feature_list_free() after usage.
833 gst_element_factory_list_get_elements (GstElementFactoryListType type,
841 data.minrank = minrank;
843 /* get the feature list using the filter */
844 result = gst_default_registry_feature_filter ((GstPluginFeatureFilter)
845 element_filter, FALSE, &data);
847 /* sort on rank and name */
848 result = g_list_sort (result, gst_plugin_feature_rank_compare_func);
854 * gst_element_factory_list_filter:
855 * @list: a #GList of #GstElementFactory to filter
857 * @direction: a #GstPadDirection to filter on
858 * @subsetonly: whether to filter on caps subsets or not.
860 * Filter out all the elementfactories in @list that can handle @caps in
861 * the given direction.
863 * If @subsetonly is %TRUE, then only the elements whose pads templates
864 * are a complete superset of @caps will be returned. Else any element
865 * whose pad templates caps can intersect with @caps will be returned.
867 * Returns: a #GList of #GstElementFactory elements that match the
868 * given requisits. Use #gst_plugin_feature_list_free after usage.
873 gst_element_factory_list_filter (GList * list,
874 const GstCaps * caps, GstPadDirection direction, gboolean subsetonly)
876 GList *result = NULL;
878 GST_DEBUG ("finding factories");
880 /* loop over all the factories */
881 for (; list; list = list->next) {
882 GstElementFactory *factory;
883 const GList *templates;
886 factory = (GstElementFactory *) list->data;
888 GST_DEBUG ("Trying %s",
889 gst_plugin_feature_get_name ((GstPluginFeature *) factory));
891 /* get the templates from the element factory */
892 templates = gst_element_factory_get_static_pad_templates (factory);
893 for (walk = (GList *) templates; walk; walk = g_list_next (walk)) {
894 GstStaticPadTemplate *templ = walk->data;
896 /* we only care about the sink templates */
897 if (templ->direction == direction) {
900 /* try to intersect the caps with the caps of the template */
901 tmpl_caps = gst_static_caps_get (&templ->static_caps);
903 /* FIXME, intersect is not the right method, we ideally want to check
904 * for a subset here */
906 /* check if the intersection is empty */
907 if ((subsetonly && gst_caps_is_subset (caps, tmpl_caps)) ||
908 (!subsetonly && gst_caps_can_intersect (caps, tmpl_caps))) {
909 /* non empty intersection, we can use this element */
910 result = g_list_prepend (result, gst_object_ref (factory));
913 gst_caps_unref (tmpl_caps);
917 return g_list_reverse (result);