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., 59 Temple Place - Suite 330,
19 * Boston, MA 02111-1307, 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
42 gst_type_find_get_type (void)
44 static GType typefind_type = 0;
46 if (G_UNLIKELY (typefind_type == 0)) {
47 typefind_type = g_pointer_type_register_static ("GstTypeFind");
53 * gst_type_find_register:
54 * @plugin: A #GstPlugin, or NULL for a static typefind function (note that
55 * passing NULL only works in GStreamer 0.10.16 and later)
56 * @name: The name for registering
57 * @rank: The rank (or importance) of this typefind function
58 * @func: The #GstTypeFindFunction to use
59 * @extensions: (transfer none) (array zero-terminated=1) (element-type utf8):
60 * Optional extensions that could belong to this type
61 * @possible_caps: Optionally the caps that could be returned when typefinding
63 * @data: Optional user data. This user data must be available until the plugin
65 * @data_notify: a #GDestroyNotify that will be called on @data when the plugin
68 * Registers a new typefind function to be used for typefinding. After
69 * registering this function will be available for typefinding.
70 * This function is typically called during an element's plugin initialization.
72 * Returns: TRUE on success, FALSE otherwise
75 gst_type_find_register (GstPlugin * plugin, const gchar * name, guint rank,
76 GstTypeFindFunction func, gchar ** extensions,
77 GstCaps * possible_caps, gpointer data, GDestroyNotify data_notify)
79 GstTypeFindFactory *factory;
81 g_return_val_if_fail (name != NULL, FALSE);
83 GST_INFO ("registering typefind function for %s", name);
85 factory = g_object_newv (GST_TYPE_TYPE_FIND_FACTORY, 0, NULL);
86 GST_DEBUG_OBJECT (factory, "using new typefind factory for %s", name);
87 g_assert (GST_IS_TYPE_FIND_FACTORY (factory));
89 gst_plugin_feature_set_name (GST_PLUGIN_FEATURE_CAST (factory), name);
90 gst_plugin_feature_set_rank (GST_PLUGIN_FEATURE_CAST (factory), rank);
92 if (factory->extensions)
93 g_strfreev (factory->extensions);
94 factory->extensions = g_strdupv (extensions);
96 gst_caps_replace (&factory->caps, possible_caps);
97 factory->function = func;
98 factory->user_data = data;
99 factory->user_data_notify = data_notify;
100 if (plugin && plugin->desc.name) {
101 GST_PLUGIN_FEATURE_CAST (factory)->plugin_name = plugin->desc.name; /* interned string */
102 GST_PLUGIN_FEATURE_CAST (factory)->plugin = plugin;
103 g_object_add_weak_pointer ((GObject *) plugin,
104 (gpointer *) & GST_PLUGIN_FEATURE_CAST (factory)->plugin);
106 GST_PLUGIN_FEATURE_CAST (factory)->plugin_name = "NULL";
107 GST_PLUGIN_FEATURE_CAST (factory)->plugin = NULL;
109 GST_PLUGIN_FEATURE_CAST (factory)->loaded = TRUE;
111 gst_registry_add_feature (gst_registry_get (),
112 GST_PLUGIN_FEATURE_CAST (factory));
117 /*** typefind function interface **********************************************/
120 * gst_type_find_peek:
121 * @find: The #GstTypeFind object the function was called with
122 * @offset: The offset
123 * @size: The number of bytes to return
125 * Returns the @size bytes of the stream to identify beginning at offset. If
126 * offset is a positive number, the offset is relative to the beginning of the
127 * stream, if offset is a negative number the offset is relative to the end of
128 * the stream. The returned memory is valid until the typefinding function
129 * returns and must not be freed.
131 * Returns: (transfer none) (array length=size): the requested data, or NULL
132 * if that data is not available.
135 gst_type_find_peek (GstTypeFind * find, gint64 offset, guint size)
137 g_return_val_if_fail (find->peek != NULL, NULL);
139 return find->peek (find->data, offset, size);
143 * gst_type_find_suggest:
144 * @find: The #GstTypeFind object the function was called with
145 * @probability: The probability in percent that the suggestion is right
146 * @caps: The fixed #GstCaps to suggest
148 * If a #GstTypeFindFunction calls this function it suggests the caps with the
149 * given probability. A #GstTypeFindFunction may supply different suggestions
151 * It is up to the caller of the #GstTypeFindFunction to interpret these values.
154 gst_type_find_suggest (GstTypeFind * find, guint probability,
155 const GstCaps * caps)
157 g_return_if_fail (find->suggest != NULL);
158 g_return_if_fail (probability <= 100);
159 g_return_if_fail (caps != NULL);
160 g_return_if_fail (gst_caps_is_fixed (caps));
162 find->suggest (find->data, probability, caps);
166 * gst_type_find_suggest_simple:
167 * @find: The #GstTypeFind object the function was called with
168 * @probability: The probability in percent that the suggestion is right
169 * @media_type: the media type of the suggested caps
170 * @fieldname: first field of the suggested caps, or NULL
171 * @...: additional arguments to the suggested caps in the same format as the
172 * arguments passed to gst_structure_new() (ie. triplets of field name,
173 * field GType and field value)
175 * If a #GstTypeFindFunction calls this function it suggests the caps with the
176 * given probability. A #GstTypeFindFunction may supply different suggestions
177 * in one call. It is up to the caller of the #GstTypeFindFunction to interpret
180 * This function is similar to gst_type_find_suggest(), only that instead of
181 * passing a #GstCaps argument you can create the caps on the fly in the same
182 * way as you can with gst_caps_new_simple().
184 * Make sure you terminate the list of arguments with a NULL argument and that
185 * the values passed have the correct type (in terms of width in bytes when
186 * passed to the vararg function - this applies particularly to gdouble and
187 * guint64 arguments).
192 gst_type_find_suggest_simple (GstTypeFind * find, guint probability,
193 const char *media_type, const char *fieldname, ...)
195 GstStructure *structure;
199 g_return_if_fail (find->suggest != NULL);
200 g_return_if_fail (probability <= 100);
201 g_return_if_fail (media_type != NULL);
203 caps = gst_caps_new_empty ();
205 va_start (var_args, fieldname);
206 structure = gst_structure_new_valist (media_type, fieldname, var_args);
209 gst_caps_append_structure (caps, structure);
210 g_return_if_fail (gst_caps_is_fixed (caps));
212 find->suggest (find->data, probability, caps);
213 gst_caps_unref (caps);
217 * gst_type_find_get_length:
218 * @find: The #GstTypeFind the function was called with
220 * Get the length of the data stream.
222 * Returns: The length of the data stream, or 0 if it is not available.
225 gst_type_find_get_length (GstTypeFind * find)
227 if (find->get_length == NULL)
230 return find->get_length (find->data);