2 * Copyright (C) 2003 Benjamin Otte <in7y118@public.uni-hamburg.de>
4 * gsttypefindfactory.c: typefinding subsystem
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Library General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Library General Public License for more details.
16 * You should have received a copy of the GNU Library General Public
17 * License along with this library; if not, write to the
18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 * Boston, MA 02111-1307, USA.
23 * SECTION:gsttypefindfactory
24 * @short_description: Information about registered typefind functions
26 * These functions allow querying informations about registered typefind
27 * functions. How to create and register these functions is described in
28 * the section <link linkend="gstreamer-Writing-typefind-functions">
29 * "Writing typefind functions"</link>.
32 * <title>how to write a simple typefinder</title>
41 * my_peek (gpointer data, gint64 offset, guint size)
43 * MyTypeFind *find = (MyTypeFind *) data;
44 * if (offset >= 0 && offset + size <= find->size) {
45 * return find->data + offset;
50 * my_suggest (gpointer data, guint probability, GstCaps *caps)
52 * MyTypeFind *find = (MyTypeFind *) data;
53 * if (probability > find->probability) {
54 * find->probability = probability;
55 * gst_caps_replace (&find->caps, caps);
59 * find_type (guint8 *data, guint size)
61 * GList *walk, *type_list;
62 * MyTypeFind find = {data, size, 0, NULL};
63 * GstTypeFind gst_find = {my_peek, my_suggest, &find, };
64 * walk = type_list = gst_type_find_factory_get_list ();
66 * GstTypeFindFactory *factory = GST_TYPE_FIND_FACTORY (walk->data);
67 * walk = g_list_next (walk)
68 * gst_type_find_factory_call_function (factory, &gst_find);
70 * g_list_free (type_list);
76 * The above example shows how to write a very simple typefinder that
77 * identifies the given data. You can get quite a bit more complicated than
80 * Last reviewed on 2005-11-09 (0.9.4)
83 #include "gst_private.h"
85 #include "gsttypefind.h"
86 #include "gsttypefindfactory.h"
87 #include "gstregistry.h"
89 GST_DEBUG_CATEGORY (gst_type_find_debug);
90 #define GST_CAT_DEFAULT gst_type_find_debug
92 static void gst_type_find_factory_class_init (gpointer g_class,
94 static void gst_type_find_factory_init (GTypeInstance * instance,
96 static void gst_type_find_factory_dispose (GObject * object);
98 static GstPluginFeatureClass *parent_class = NULL;
101 gst_type_find_factory_get_type (void)
103 static GType typefind_type = 0;
105 if (G_UNLIKELY (typefind_type == 0)) {
106 static const GTypeInfo typefind_info = {
107 sizeof (GstTypeFindFactoryClass),
110 gst_type_find_factory_class_init,
113 sizeof (GstTypeFindFactory),
115 gst_type_find_factory_init,
119 typefind_type = g_type_register_static (GST_TYPE_PLUGIN_FEATURE,
120 "GstTypeFindFactory", &typefind_info, 0);
121 GST_DEBUG_CATEGORY_INIT (gst_type_find_debug, "GST_TYPEFIND",
122 GST_DEBUG_FG_GREEN, "typefinding subsystem");
125 return typefind_type;
129 gst_type_find_factory_class_init (gpointer g_class, gpointer class_data)
131 GObjectClass *object_class = G_OBJECT_CLASS (g_class);
133 parent_class = g_type_class_peek_parent (g_class);
135 object_class->dispose = gst_type_find_factory_dispose;
139 gst_type_find_factory_init (GTypeInstance * instance, gpointer g_class)
141 GstTypeFindFactory *factory = GST_TYPE_FIND_FACTORY (instance);
143 factory->user_data = factory;
144 factory->user_data_notify = NULL;
148 gst_type_find_factory_dispose (GObject * object)
150 GstTypeFindFactory *factory = GST_TYPE_FIND_FACTORY (object);
153 gst_caps_unref (factory->caps);
154 factory->caps = NULL;
156 if (factory->extensions) {
157 g_strfreev (factory->extensions);
158 factory->extensions = NULL;
160 if (factory->user_data_notify && factory->user_data) {
161 factory->user_data_notify (factory->user_data);
162 factory->user_data = NULL;
165 G_OBJECT_CLASS (parent_class)->dispose (object);
169 * gst_type_find_factory_get_list:
171 * Gets the list of all registered typefind factories. You must free the
172 * list using g_list_free.
174 * Returns: the list of all registered #GstTypeFindFactory.
177 gst_type_find_factory_get_list (void)
179 return gst_registry_get_feature_list (gst_registry_get_default (),
180 GST_TYPE_TYPE_FIND_FACTORY);
184 * gst_type_find_factory_get_caps:
185 * @factory: A #GstTypeFindFactory
187 * Gets the #GstCaps associated with a typefind factory.
189 * Returns: The #GstCaps associated with this factory
192 gst_type_find_factory_get_caps (GstTypeFindFactory * factory)
194 g_return_val_if_fail (GST_IS_TYPE_FIND_FACTORY (factory), NULL);
196 return factory->caps;
200 * gst_type_find_factory_get_extensions:
201 * @factory: A #GstTypeFindFactory
203 * Gets the extensions associated with a #GstTypeFindFactory. The returned
204 * array should not be changed. If you need to change stuff in it, you should
205 * copy it using g_stdupv(). This function may return NULL to indicate
208 * Returns: a NULL-terminated array of extensions associated with this factory
211 gst_type_find_factory_get_extensions (GstTypeFindFactory * factory)
213 g_return_val_if_fail (GST_IS_TYPE_FIND_FACTORY (factory), NULL);
215 return factory->extensions;
219 * gst_type_find_factory_call_function:
220 * @factory: A #GstTypeFindFactory
221 * @find: A properly setup #GstTypeFind entry. The get_data and suggest_type
222 * members must be set.
224 * Calls the #GstTypeFindFunction associated with this factory.
227 gst_type_find_factory_call_function (GstTypeFindFactory * factory,
230 GstTypeFindFactory *new_factory;
232 g_return_if_fail (GST_IS_TYPE_FIND_FACTORY (factory));
233 g_return_if_fail (find != NULL);
234 g_return_if_fail (find->peek != NULL);
235 g_return_if_fail (find->suggest != NULL);
238 GST_TYPE_FIND_FACTORY (gst_plugin_feature_load (GST_PLUGIN_FEATURE
241 g_assert (new_factory->function != NULL);
243 new_factory->function (find, new_factory->user_data);