gstreamer/gst/gsttypefind.c

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/* 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
*
*/
#include "gst_private.h"
#include "gstinfo.h"
#include "gsttypefind.h"
#include "gstregistry.h"
#include "gsttypefindfactory.h"
GST_DEBUG_CATEGORY_EXTERN (gst_type_find_debug);
#define GST_CAT_DEFAULT gst_type_find_debug
/**
* gst_type_find_register:
* @plugin: the GstPlugin to register with
* @name: the name for registering
* @rank: rank (or importance) of this typefind function
* @func: the function to use for typefinding
* @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.
*
* 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)
{
GstTypeFindFactory *factory;
g_return_val_if_fail (plugin != NULL, FALSE);
g_return_val_if_fail (name != NULL, FALSE);
g_return_val_if_fail (func != NULL, FALSE);
GST_INFO ("registering typefind function for %s", name);
factory =
GST_TYPE_FIND_FACTORY (gst_registry_find_feature (gst_registry_get_default
(), name, GST_TYPE_TYPE_FIND_FACTORY));
if (!factory) {
factory = g_object_new (GST_TYPE_TYPE_FIND_FACTORY, 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 (factory), name);
gst_plugin_add_feature (plugin, GST_PLUGIN_FEATURE (factory));
} else {
GST_DEBUG_OBJECT (factory, "using old typefind factory for %s", name);
}
gst_plugin_feature_set_rank (GST_PLUGIN_FEATURE (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;
return TRUE;
}
/*** typefind function interface **********************************************/
/**
* gst_type_find_peek:
* @find: the find object the function was called with
* @offset: the offset
* @size: the number of bytes to return
*
* Returns 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.
* If NULL is returned, that data is not available.
*
* 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 find object the function was called with
* @probability: the probability in percent that the suggestion is right
* @caps: the fixed caps to suggest
*
* If a typefind function calls this function it suggests the caps with the
* given probability. A typefind function may supply different suggestions
* in one call.
* It is up to the caller of the typefind function 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_get_length:
* @find: the find object 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);
}