root/gst/gsttypefind.c
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DEFINITIONS
This source file includes following definitions.
- gst_type_find_get_type
- gst_type_find_register
- gst_type_find_peek
- gst_type_find_suggest
- gst_type_find_suggest_simple
- gst_type_find_get_length
/* GStreamer
* Copyright (C) 2003 Benjamin Otte <in7y118@public.uni-hamburg.de>
*
* gsttypefind.c: typefinding subsystem
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/**
* SECTION:gsttypefind
* @short_description: Stream type detection
*
* The following functions allow you to detect the media type of an unknown
* stream.
*
* Last reviewed on 2005-11-09 (0.9.4)
*/
#include "gst_private.h"
#include "gstinfo.h"
#include "gsttypefind.h"
#include "gstregistry.h"
#include "gsttypefindfactory.h"
GST_DEBUG_CATEGORY_EXTERN (type_find_debug);
#define GST_CAT_DEFAULT type_find_debug
GType
gst_type_find_get_type (void)
{
static GType typefind_type = 0;
if (G_UNLIKELY (typefind_type == 0)) {
typefind_type = g_pointer_type_register_static ("GstTypeFind");
}
return typefind_type;
}
/**
* gst_type_find_register:
* @plugin: A #GstPlugin, or NULL for a static typefind function (note that
* passing NULL only works in GStreamer 0.10.16 and later)
* @name: The name for registering
* @rank: The rank (or importance) of this typefind function
* @func: The #GstTypeFindFunction to use
* @extensions: Optional extensions that could belong to this type
* @possible_caps: Optionally the caps that could be returned when typefinding
* succeeds
* @data: Optional user data. This user data must be available until the plugin
* is unloaded.
* @data_notify: a #GDestroyNotify that will be called on @data when the plugin
* is unloaded.
*
* Registers a new typefind function to be used for typefinding. After
* registering this function will be available for typefinding.
* This function is typically called during an element's plugin initialization.
*
* Returns: TRUE on success, FALSE otherwise
*/
gboolean
gst_type_find_register (GstPlugin * plugin, const gchar * name, guint rank,
GstTypeFindFunction func, gchar ** extensions,
const GstCaps * possible_caps, gpointer data, GDestroyNotify data_notify)
{
GstTypeFindFactory *factory;
g_return_val_if_fail (name != NULL, FALSE);
GST_INFO ("registering typefind function for %s", name);
factory = g_object_newv (GST_TYPE_TYPE_FIND_FACTORY, 0, NULL);
GST_DEBUG_OBJECT (factory, "using new typefind factory for %s", name);
g_assert (GST_IS_TYPE_FIND_FACTORY (factory));
gst_plugin_feature_set_name (GST_PLUGIN_FEATURE_CAST (factory), name);
gst_plugin_feature_set_rank (GST_PLUGIN_FEATURE_CAST (factory), rank);
if (factory->extensions)
g_strfreev (factory->extensions);
factory->extensions = g_strdupv (extensions);
gst_caps_replace (&factory->caps, (GstCaps *) possible_caps);
factory->function = func;
factory->user_data = data;
factory->user_data_notify = data_notify;
if (plugin && plugin->desc.name) {
GST_PLUGIN_FEATURE_CAST (factory)->plugin_name = plugin->desc.name; /* interned string */
} else {
GST_PLUGIN_FEATURE_CAST (factory)->plugin_name = "NULL";
}
GST_PLUGIN_FEATURE_CAST (factory)->loaded = TRUE;
gst_registry_add_feature (gst_registry_get_default (),
GST_PLUGIN_FEATURE_CAST (factory));
return TRUE;
}
/*** typefind function interface **********************************************/
/**
* gst_type_find_peek:
* @find: The #GstTypeFind object the function was called with
* @offset: The offset
* @size: The number of bytes to return
*
* Returns the @size bytes of the stream to identify beginning at offset. If
* offset is a positive number, the offset is relative to the beginning of the
* stream, if offset is a negative number the offset is relative to the end of
* the stream. The returned memory is valid until the typefinding function
* returns and must not be freed.
*
* Returns: the requested data, or NULL if that data is not available.
*/
guint8 *
gst_type_find_peek (GstTypeFind * find, gint64 offset, guint size)
{
g_return_val_if_fail (find->peek != NULL, NULL);
return find->peek (find->data, offset, size);
}
/**
* gst_type_find_suggest:
* @find: The #GstTypeFind object the function was called with
* @probability: The probability in percent that the suggestion is right
* @caps: The fixed #GstCaps to suggest
*
* If a #GstTypeFindFunction calls this function it suggests the caps with the
* given probability. A #GstTypeFindFunction may supply different suggestions
* in one call.
* It is up to the caller of the #GstTypeFindFunction to interpret these values.
*/
void
gst_type_find_suggest (GstTypeFind * find, guint probability,
const GstCaps * caps)
{
g_return_if_fail (find->suggest != NULL);
g_return_if_fail (probability <= 100);
g_return_if_fail (caps != NULL);
g_return_if_fail (gst_caps_is_fixed (caps));
find->suggest (find->data, probability, caps);
}
/**
* gst_type_find_suggest_simple:
* @find: The #GstTypeFind object the function was called with
* @probability: The probability in percent that the suggestion is right
* @media_type: the media type of the suggested caps
* @fieldname: first field of the suggested caps, or NULL
* @...: additional arguments to the suggested caps in the same format as the
* arguments passed to gst_structure_new() (ie. triplets of field name,
* field GType and field value)
*
* If a #GstTypeFindFunction calls this function it suggests the caps with the
* given probability. A #GstTypeFindFunction may supply different suggestions
* in one call. It is up to the caller of the #GstTypeFindFunction to interpret
* these values.
*
* This function is similar to gst_type_find_suggest(), only that instead of
* passing a #GstCaps argument you can create the caps on the fly in the same
* way as you can with gst_caps_new_simple().
*
* Make sure you terminate the list of arguments with a NULL argument and that
* the values passed have the correct type (in terms of width in bytes when
* passed to the vararg function - this applies particularly to gdouble and
* guint64 arguments).
*
* Since: 0.10.20
*/
void
gst_type_find_suggest_simple (GstTypeFind * find, guint probability,
const char *media_type, const char *fieldname, ...)
{
GstStructure *structure;
va_list var_args;
GstCaps *caps;
g_return_if_fail (find->suggest != NULL);
g_return_if_fail (probability <= 100);
g_return_if_fail (media_type != NULL);
caps = gst_caps_new_empty ();
va_start (var_args, fieldname);
structure = gst_structure_new_valist (media_type, fieldname, var_args);
va_end (var_args);
gst_caps_append_structure (caps, structure);
g_return_if_fail (gst_caps_is_fixed (caps));
find->suggest (find->data, probability, caps);
gst_caps_unref (caps);
}
/**
* gst_type_find_get_length:
* @find: The #GstTypeFind the function was called with
*
* Get the length of the data stream.
*
* Returns: The length of the data stream, or 0 if it is not available.
*/
guint64
gst_type_find_get_length (GstTypeFind * find)
{
if (find->get_length == NULL)
return 0;
return find->get_length (find->data);
}