1 /* GStreamer

     2  * Copyright (C) 2003 Benjamin Otte <in7y118@public.uni-hamburg.de>

     3  *

     4  * gsttypefind.c: typefinding subsystem

     5  *

     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.

    10  *

    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.

    15  *

    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.

    20  */

    21 

    22 /**

    23  * SECTION:gsttypefind

    24  * @short_description: Stream type detection

    25  *

    26  * The following functions allow you to detect the media type of an unknown

    27  * stream.

    28  *

    29  * Last reviewed on 2005-11-09 (0.9.4)

    30  */

    31 

    32 #include "gst_private.h"

    33 #include "gstinfo.h"

    34 #include "gsttypefind.h"

    35 #include "gstregistry.h"

    36 #include "gsttypefindfactory.h"

    37 

    38 GST_DEBUG_CATEGORY_EXTERN (type_find_debug);

    39 #define GST_CAT_DEFAULT type_find_debug

    40 

    41 #ifdef __SYMBIAN32__

    42 EXPORT_C

    43 #endif

    44 GType

    45 gst_type_find_get_type (void)

    46 {

    47   static GType typefind_type = 0;

    48 

    49   if (G_UNLIKELY (typefind_type == 0)) {

    50     typefind_type = g_pointer_type_register_static ("GstTypeFind");

    51   }

    52   return typefind_type;

    53 }

    54 

    55 /**

    56  * gst_type_find_register:

    57  * @plugin: A #GstPlugin, or NULL for a static typefind function (note that

    58  *    passing NULL only works in GStreamer 0.10.16 and later)

    59  * @name: The name for registering

    60  * @rank: The rank (or importance) of this typefind function

    61  * @func: The #GstTypeFindFunction to use

    62  * @extensions: Optional extensions that could belong to this type

    63  * @possible_caps: Optionally the caps that could be returned when typefinding

    64  *                 succeeds

    65  * @data: Optional user data. This user data must be available until the plugin

    66  *        is unloaded.

    67  * @data_notify: a #GDestroyNotify that will be called on @data when the plugin

    68  *        is unloaded.

    69  *

    70  * Registers a new typefind function to be used for typefinding. After

    71  * registering this function will be available for typefinding.

    72  * This function is typically called during an element's plugin initialization.

    73  *

    74  * Returns: TRUE on success, FALSE otherwise

    75  */

    76 #ifdef __SYMBIAN32__

    77 EXPORT_C

    78 #endif

    79 

    80 gboolean

    81 gst_type_find_register (GstPlugin * plugin, const gchar * name, guint rank,

    82     GstTypeFindFunction func, gchar ** extensions,

    83     const GstCaps * possible_caps, gpointer data, GDestroyNotify data_notify)

    84 {

    85   GstTypeFindFactory *factory;

    86 

    87   g_return_val_if_fail (name != NULL, FALSE);

    88   g_return_val_if_fail (func != NULL, FALSE);

    89 

    90   GST_INFO ("registering typefind function for %s", name);

    91 

    92   factory = g_object_new (GST_TYPE_TYPE_FIND_FACTORY, NULL);

    93   GST_DEBUG_OBJECT (factory, "using new typefind factory for %s", name);

    94   g_assert (GST_IS_TYPE_FIND_FACTORY (factory));

    95   gst_plugin_feature_set_name (GST_PLUGIN_FEATURE (factory), name);

    96 

    97   gst_plugin_feature_set_rank (GST_PLUGIN_FEATURE (factory), rank);

    98   if (factory->extensions)

    99     g_strfreev (factory->extensions);

   100 

   101   factory->extensions = g_strdupv (extensions);

   102   gst_caps_replace (&factory->caps, (GstCaps *) possible_caps);

   103   factory->function = func;

   104   factory->user_data = data;

   105   factory->user_data_notify = data_notify;

   106   if (plugin && plugin->desc.name) {

   107     GST_PLUGIN_FEATURE (factory)->plugin_name = plugin->desc.name;      /* interned string */

   108   } else {

   109     GST_PLUGIN_FEATURE (factory)->plugin_name = "NULL";

   110   }

   111   GST_PLUGIN_FEATURE (factory)->loaded = TRUE;

   112 

   113   gst_registry_add_feature (gst_registry_get_default (),

   114       GST_PLUGIN_FEATURE (factory));

   115 

   116   return TRUE;

   117 }

   118 

   119 /*** typefind function interface **********************************************/

   120 

   121 /**

   122  * gst_type_find_peek:

   123  * @find: The #GstTypeFind object the function was called with

   124  * @offset: The offset

   125  * @size: The number of bytes to return

   126  *

   127  * Returns the @size bytes of the stream to identify beginning at offset. If

   128  * offset is a positive number, the offset is relative to the beginning of the

   129  * stream, if offset is a negative number the offset is relative to the end of

   130  * the stream. The returned memory is valid until the typefinding function

   131  * returns and must not be freed.

   132  *

   133  * Returns: the requested data, or NULL if that data is not available.

   134  */

   135 #ifdef __SYMBIAN32__

   136 EXPORT_C

   137 #endif

   138 

   139 guint8 *

   140 gst_type_find_peek (GstTypeFind * find, gint64 offset, guint size)

   141 {

   142   g_return_val_if_fail (find->peek != NULL, NULL);

   143 

   144   return find->peek (find->data, offset, size);

   145 }

   146 

   147 /**

   148  * gst_type_find_suggest:

   149  * @find: The #GstTypeFind object the function was called with

   150  * @probability: The probability in percent that the suggestion is right

   151  * @caps: The fixed #GstCaps to suggest

   152  *

   153  * If a #GstTypeFindFunction calls this function it suggests the caps with the

   154  * given probability. A #GstTypeFindFunction may supply different suggestions

   155  * in one call.

   156  * It is up to the caller of the #GstTypeFindFunction to interpret these values.

   157  */

   158 #ifdef __SYMBIAN32__

   159 EXPORT_C

   160 #endif

   161 

   162 void

   163 gst_type_find_suggest (GstTypeFind * find, guint probability,

   164     const GstCaps * caps)

   165 {

   166   g_return_if_fail (find->suggest != NULL);

   167   g_return_if_fail (probability <= 100);

   168   g_return_if_fail (caps != NULL);

   169   g_return_if_fail (gst_caps_is_fixed (caps));

   170 

   171   find->suggest (find->data, probability, caps);

   172 }

   173 

   174 /**

   175  * gst_type_find_get_length:

   176  * @find: The #GstTypeFind the function was called with

   177  *

   178  * Get the length of the data stream.

   179  *

   180  * Returns: The length of the data stream, or 0 if it is not available.

   181  */

   182 #ifdef __SYMBIAN32__

   183 EXPORT_C

   184 #endif

   185 

   186 guint64

   187 gst_type_find_get_length (GstTypeFind * find)

   188 {

   189   if (find->get_length == NULL)

   190     return 0;

   191 

   192   return find->get_length (find->data);

   193 }