2 * Copyright (C) 2003 Benjamin Otte <in7y118@public.uni-hamburg.de>
4 * gsttypefind.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., 51 Franklin St, Fifth Floor,
19 * Boston, MA 02110-1301, USA.
24 * @short_description: Stream type detection
26 * The following functions allow you to detect the media type of an unknown
29 * Last reviewed on 2005-11-09 (0.9.4)
32 #include "gst_private.h"
34 #include "gsttypefind.h"
35 #include "gstregistry.h"
36 #include "gsttypefindfactory.h"
38 GST_DEBUG_CATEGORY_EXTERN (type_find_debug);
39 #define GST_CAT_DEFAULT type_find_debug
41 G_DEFINE_POINTER_TYPE (GstTypeFind, gst_type_find);
44 * gst_type_find_register:
45 * @plugin: A #GstPlugin, or NULL for a static typefind function
46 * @name: The name for registering
47 * @rank: The rank (or importance) of this typefind function
48 * @func: The #GstTypeFindFunction to use
49 * @extensions: (allow-none): Optional comma-separated list of extensions
50 * that could belong to this type
51 * @possible_caps: Optionally the caps that could be returned when typefinding
53 * @data: Optional user data. This user data must be available until the plugin
55 * @data_notify: a #GDestroyNotify that will be called on @data when the plugin
58 * Registers a new typefind function to be used for typefinding. After
59 * registering this function will be available for typefinding.
60 * This function is typically called during an element's plugin initialization.
62 * Returns: TRUE on success, FALSE otherwise
65 gst_type_find_register (GstPlugin * plugin, const gchar * name, guint rank,
66 GstTypeFindFunction func, const gchar * extensions,
67 GstCaps * possible_caps, gpointer data, GDestroyNotify data_notify)
69 GstTypeFindFactory *factory;
71 g_return_val_if_fail (name != NULL, FALSE);
73 GST_INFO ("registering typefind function for %s", name);
75 factory = g_object_newv (GST_TYPE_TYPE_FIND_FACTORY, 0, NULL);
76 GST_DEBUG_OBJECT (factory, "using new typefind factory for %s", name);
77 g_assert (GST_IS_TYPE_FIND_FACTORY (factory));
79 gst_plugin_feature_set_name (GST_PLUGIN_FEATURE_CAST (factory), name);
80 gst_plugin_feature_set_rank (GST_PLUGIN_FEATURE_CAST (factory), rank);
82 if (factory->extensions) {
83 g_strfreev (factory->extensions);
84 factory->extensions = NULL;
87 factory->extensions = g_strsplit (extensions, ",", -1);
89 gst_caps_replace (&factory->caps, possible_caps);
90 factory->function = func;
91 factory->user_data = data;
92 factory->user_data_notify = data_notify;
93 if (plugin && plugin->desc.name) {
94 GST_PLUGIN_FEATURE_CAST (factory)->plugin_name = plugin->desc.name; /* interned string */
95 GST_PLUGIN_FEATURE_CAST (factory)->plugin = plugin;
96 g_object_add_weak_pointer ((GObject *) plugin,
97 (gpointer *) & GST_PLUGIN_FEATURE_CAST (factory)->plugin);
99 GST_PLUGIN_FEATURE_CAST (factory)->plugin_name = "NULL";
100 GST_PLUGIN_FEATURE_CAST (factory)->plugin = NULL;
102 GST_PLUGIN_FEATURE_CAST (factory)->loaded = TRUE;
104 gst_registry_add_feature (gst_registry_get (),
105 GST_PLUGIN_FEATURE_CAST (factory));
110 /*** typefind function interface **********************************************/
113 * gst_type_find_peek:
114 * @find: The #GstTypeFind object the function was called with
115 * @offset: The offset
116 * @size: The number of bytes to return
118 * Returns the @size bytes of the stream to identify beginning at offset. If
119 * offset is a positive number, the offset is relative to the beginning of the
120 * stream, if offset is a negative number the offset is relative to the end of
121 * the stream. The returned memory is valid until the typefinding function
122 * returns and must not be freed.
124 * Returns: (transfer none) (array length=size): the requested data, or NULL
125 * if that data is not available.
128 gst_type_find_peek (GstTypeFind * find, gint64 offset, guint size)
130 g_return_val_if_fail (find->peek != NULL, NULL);
132 return find->peek (find->data, offset, size);
136 * gst_type_find_suggest:
137 * @find: The #GstTypeFind object the function was called with
138 * @probability: The probability in percent that the suggestion is right
139 * @caps: The fixed #GstCaps to suggest
141 * If a #GstTypeFindFunction calls this function it suggests the caps with the
142 * given probability. A #GstTypeFindFunction may supply different suggestions
144 * It is up to the caller of the #GstTypeFindFunction to interpret these values.
147 gst_type_find_suggest (GstTypeFind * find, guint probability, GstCaps * caps)
149 g_return_if_fail (find->suggest != NULL);
150 g_return_if_fail (probability <= 100);
151 g_return_if_fail (caps != NULL);
152 g_return_if_fail (gst_caps_is_fixed (caps));
154 find->suggest (find->data, probability, caps);
158 * gst_type_find_suggest_simple:
159 * @find: The #GstTypeFind object the function was called with
160 * @probability: The probability in percent that the suggestion is right
161 * @media_type: the media type of the suggested caps
162 * @fieldname: first field of the suggested caps, or NULL
163 * @...: additional arguments to the suggested caps in the same format as the
164 * arguments passed to gst_structure_new() (ie. triplets of field name,
165 * field GType and field value)
167 * If a #GstTypeFindFunction calls this function it suggests the caps with the
168 * given probability. A #GstTypeFindFunction may supply different suggestions
169 * in one call. It is up to the caller of the #GstTypeFindFunction to interpret
172 * This function is similar to gst_type_find_suggest(), only that instead of
173 * passing a #GstCaps argument you can create the caps on the fly in the same
174 * way as you can with gst_caps_new_simple().
176 * Make sure you terminate the list of arguments with a NULL argument and that
177 * the values passed have the correct type (in terms of width in bytes when
178 * passed to the vararg function - this applies particularly to gdouble and
179 * guint64 arguments).
182 gst_type_find_suggest_simple (GstTypeFind * find, guint probability,
183 const char *media_type, const char *fieldname, ...)
185 GstStructure *structure;
189 g_return_if_fail (find->suggest != NULL);
190 g_return_if_fail (probability <= 100);
191 g_return_if_fail (media_type != NULL);
193 caps = gst_caps_new_empty ();
195 va_start (var_args, fieldname);
196 structure = gst_structure_new_valist (media_type, fieldname, var_args);
199 gst_caps_append_structure (caps, structure);
200 g_return_if_fail (gst_caps_is_fixed (caps));
202 find->suggest (find->data, probability, caps);
203 gst_caps_unref (caps);
207 * gst_type_find_get_length:
208 * @find: The #GstTypeFind the function was called with
210 * Get the length of the data stream.
212 * Returns: The length of the data stream, or 0 if it is not available.
215 gst_type_find_get_length (GstTypeFind * find)
217 if (find->get_length == NULL)
220 return find->get_length (find->data);