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
28 #include "gst_private.h"
30 #include "gsttypefind.h"
31 #include "gstregistry.h"
32 #include "gsttypefindfactory.h"
34 GST_DEBUG_CATEGORY_EXTERN (gst_type_find_debug);
35 #define GST_CAT_DEFAULT gst_type_find_debug
38 * gst_type_find_register:
39 * @plugin: the GstPlugin to register with
40 * @name: the name for registering
41 * @rank: rank (or importance) of this typefind function
42 * @func: the function to use for typefinding
43 * @extensions: optional extensions that could belong to this type
44 * @possible_caps: optionally the caps that could be returned when typefinding succeeds
45 * @data: optional user data. This user data must be available until the plugin
48 * Registers a new typefind function to be used for typefinding. After
49 * registering this function will be available for typefinding.
50 * This function is typically called during an element's plugin initialization.
52 * Returns: TRUE on success, FALSE otherwise
55 gst_type_find_register (GstPlugin * plugin, const gchar * name, guint rank,
56 GstTypeFindFunction func, gchar ** extensions,
57 const GstCaps * possible_caps, gpointer data)
59 GstTypeFindFactory *factory;
61 g_return_val_if_fail (plugin != NULL, FALSE);
62 g_return_val_if_fail (name != NULL, FALSE);
63 g_return_val_if_fail (func != NULL, FALSE);
65 GST_INFO ("registering typefind function for %s", name);
67 factory = g_object_new (GST_TYPE_TYPE_FIND_FACTORY, NULL);
68 GST_DEBUG_OBJECT (factory, "using new typefind factory for %s", name);
69 g_assert (GST_IS_TYPE_FIND_FACTORY (factory));
70 gst_plugin_feature_set_name (GST_PLUGIN_FEATURE (factory), name);
72 gst_plugin_feature_set_rank (GST_PLUGIN_FEATURE (factory), rank);
73 if (factory->extensions)
74 g_strfreev (factory->extensions);
76 factory->extensions = g_strdupv (extensions);
77 gst_caps_replace (&factory->caps, (GstCaps *) possible_caps);
78 factory->function = func;
79 factory->user_data = data;
80 GST_PLUGIN_FEATURE (factory)->plugin_name = g_strdup (plugin->desc.name);
81 GST_PLUGIN_FEATURE (factory)->loaded = TRUE;
83 gst_registry_add_feature (gst_registry_get_default (),
84 GST_PLUGIN_FEATURE (factory));
89 /*** typefind function interface **********************************************/
93 * @find: the find object the function was called with
95 * @size: the number of bytes to return
97 * Returns size bytes of the stream to identify beginning at offset. If offset
98 * is a positive number, the offset is relative to the beginning of the stream,
99 * if offset is a negative number the offset is relative to the end of the
100 * stream. The returned memory is valid until the typefinding function returns
101 * and must not be freed.
102 * If NULL is returned, that data is not available.
104 * Returns: the requested data or NULL if that data is not available.
107 gst_type_find_peek (GstTypeFind * find, gint64 offset, guint size)
109 g_return_val_if_fail (find->peek != NULL, NULL);
111 return find->peek (find->data, offset, size);
115 * gst_type_find_suggest:
116 * @find: the find object the function was called with
117 * @probability: the probability in percent that the suggestion is right
118 * @caps: the fixed caps to suggest
120 * If a typefind function calls this function it suggests the caps with the
121 * given probability. A typefind function may supply different suggestions
123 * It is up to the caller of the typefind function to interpret these values.
126 gst_type_find_suggest (GstTypeFind * find, guint probability,
127 const GstCaps * caps)
129 g_return_if_fail (find->suggest != NULL);
130 g_return_if_fail (probability <= 100);
131 g_return_if_fail (caps != NULL);
132 g_return_if_fail (gst_caps_is_fixed (caps));
134 find->suggest (find->data, probability, caps);
138 * gst_type_find_get_length:
139 * @find: the find object the function was called with
141 * Get the length of the data stream.
143 * Returns: the length of the data stream or 0 if it is not available.
146 gst_type_find_get_length (GstTypeFind * find)
148 if (find->get_length == NULL)
151 return find->get_length (find->data);