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: Optional extensions that could belong to this type
60 * @possible_caps: Optionally the caps that could be returned when typefinding
62 * @data: Optional user data. This user data must be available until the plugin
64 * @data_notify: a #GDestroyNotify that will be called on @data when the plugin
67 * Registers a new typefind function to be used for typefinding. After
68 * registering this function will be available for typefinding.
69 * This function is typically called during an element's plugin initialization.
71 * Returns: TRUE on success, FALSE otherwise
74 gst_type_find_register (GstPlugin * plugin, const gchar * name, guint rank,
75 GstTypeFindFunction func, gchar ** extensions,
76 const GstCaps * possible_caps, gpointer data, GDestroyNotify data_notify)
78 GstTypeFindFactory *factory;
80 g_return_val_if_fail (name != NULL, FALSE);
81 g_return_val_if_fail (func != NULL, FALSE);
83 GST_INFO ("registering typefind function for %s", name);
85 factory = g_object_new (GST_TYPE_TYPE_FIND_FACTORY, 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 (factory), name);
90 gst_plugin_feature_set_rank (GST_PLUGIN_FEATURE (factory), rank);
92 if (factory->extensions)
93 g_strfreev (factory->extensions);
94 factory->extensions = g_strdupv (extensions);
96 gst_caps_replace (&factory->caps, (GstCaps *) 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 (factory)->plugin_name = plugin->desc.name; /* interned string */
103 GST_PLUGIN_FEATURE (factory)->plugin_name = "NULL";
105 GST_PLUGIN_FEATURE (factory)->loaded = TRUE;
107 gst_registry_add_feature (gst_registry_get_default (),
108 GST_PLUGIN_FEATURE (factory));
113 /*** typefind function interface **********************************************/
116 * gst_type_find_peek:
117 * @find: The #GstTypeFind object the function was called with
118 * @offset: The offset
119 * @size: The number of bytes to return
121 * Returns the @size bytes of the stream to identify beginning at offset. If
122 * offset is a positive number, the offset is relative to the beginning of the
123 * stream, if offset is a negative number the offset is relative to the end of
124 * the stream. The returned memory is valid until the typefinding function
125 * returns and must not be freed.
127 * Returns: the requested data, or NULL if that data is not available.
130 gst_type_find_peek (GstTypeFind * find, gint64 offset, guint size)
132 g_return_val_if_fail (find->peek != NULL, NULL);
134 return find->peek (find->data, offset, size);
138 * gst_type_find_suggest:
139 * @find: The #GstTypeFind object the function was called with
140 * @probability: The probability in percent that the suggestion is right
141 * @caps: The fixed #GstCaps to suggest
143 * If a #GstTypeFindFunction calls this function it suggests the caps with the
144 * given probability. A #GstTypeFindFunction may supply different suggestions
146 * It is up to the caller of the #GstTypeFindFunction to interpret these values.
149 gst_type_find_suggest (GstTypeFind * find, guint probability,
150 const GstCaps * caps)
152 g_return_if_fail (find->suggest != NULL);
153 g_return_if_fail (probability <= 100);
154 g_return_if_fail (caps != NULL);
155 g_return_if_fail (gst_caps_is_fixed (caps));
157 find->suggest (find->data, probability, caps);
161 * gst_type_find_suggest_simple:
162 * @find: The #GstTypeFind object the function was called with
163 * @probability: The probability in percent that the suggestion is right
164 * @media_type: the media type of the suggested caps
165 * @fieldname: first field of the suggested caps, or NULL
166 * @...: additional arguments to the suggested caps in the same format as the
167 * arguments passed to gst_structure_new() (ie. triplets of field name,
168 * field GType and field value)
170 * If a #GstTypeFindFunction calls this function it suggests the caps with the
171 * given probability. A #GstTypeFindFunction may supply different suggestions
172 * in one call. It is up to the caller of the #GstTypeFindFunction to interpret
175 * This function is similar to gst_type_find_suggest(), only that instead of
176 * passing a #GstCaps argument you can create the caps on the fly in the same
177 * way as you can with gst_caps_new_simple().
179 * Make sure you terminate the list of arguments with a NULL argument and that
180 * the values passed have the correct type (in terms of width in bytes when
181 * passed to the vararg function - this applies particularly to gdouble and
182 * guint64 arguments).
187 gst_type_find_suggest_simple (GstTypeFind * find, guint probability,
188 const char *media_type, const char *fieldname, ...)
190 GstStructure *structure;
194 g_return_if_fail (find->suggest != NULL);
195 g_return_if_fail (probability <= 100);
196 g_return_if_fail (media_type != NULL);
198 caps = gst_caps_new_empty ();
200 va_start (var_args, fieldname);
201 structure = gst_structure_new_valist (media_type, fieldname, var_args);
204 gst_caps_append_structure (caps, structure);
205 g_return_if_fail (gst_caps_is_fixed (caps));
207 find->suggest (find->data, probability, caps);
208 gst_caps_unref (caps);
212 * gst_type_find_get_length:
213 * @find: The #GstTypeFind the function was called with
215 * Get the length of the data stream.
217 * Returns: The length of the data stream, or 0 if it is not available.
220 gst_type_find_get_length (GstTypeFind * find)
222 if (find->get_length == NULL)
225 return find->get_length (find->data);