GstTypeFindFactory

GstTypeFindFactory — Information about registered typefind functions

Synopsis

#include <gst/gst.h>

struct              GstTypeFindFactory;
GList *		           gst_type_find_factory_get_list      (void);
gchar **	           gst_type_find_factory_get_extensions
                                                        (GstTypeFindFactory *factory);
GstCaps *	          gst_type_find_factory_get_caps      (GstTypeFindFactory *factory);
void                gst_type_find_factory_call_function (GstTypeFindFactory *factory,
                                                         GstTypeFind *find);

Object Hierarchy

  GObject
   +----GstObject
         +----GstPluginFeature
               +----GstTypeFindFactory

Description

These functions allow querying informations about registered typefind functions. How to create and register these functions is described in the section "Writing typefind functions".

Example 17. how to write a simple typefinder

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typedef struct {
  guint8 *data;
  guint size;
  guint probability;
  GstCaps *data;
} MyTypeFind;
static void
my_peek (gpointer data, gint64 offset, guint size)
{
  MyTypeFind *find = (MyTypeFind *) data;
  if (offset >= 0 && offset + size <= find->size) {
    return find->data + offset;
  }
  return NULL;
}
static void
my_suggest (gpointer data, guint probability, GstCaps *caps)
{
  MyTypeFind *find = (MyTypeFind *) data;
  if (probability > find->probability) {
    find->probability = probability;
    gst_caps_replace (&find->caps, caps);
  }
}
static GstCaps *
find_type (guint8 *data, guint size)
{
  GList *walk, *type_list;
  MyTypeFind find = {data, size, 0, NULL};
  GstTypeFind gst_find = {my_peek, my_suggest, &find, };
  walk = type_list = gst_type_find_factory_get_list ();
  while (walk) {
    GstTypeFindFactory *factory = GST_TYPE_FIND_FACTORY (walk->data);
    walk = g_list_next (walk)
    gst_type_find_factory_call_function (factory, &gst_find);
  }
  g_list_free (type_list);
  return find.caps;
};


The above example shows how to write a very simple typefinder that identifies the given data. You can get quite a bit more complicated than that though.

Last reviewed on 2005-11-09 (0.9.4)

Details

struct GstTypeFindFactory

struct GstTypeFindFactory;

Object that stores information about a typefind function.

gst_type_find_factory_get_list ()

GList *		           gst_type_find_factory_get_list      (void);

Gets the list of all registered typefind factories. You must free the list using gst_plugin_feature_list_free().

The returned factories are sorted by highest rank first, and then by factory name. (behaviour change since 0.10.26)

Free-function: gst_plugin_feature_list_free

Returns :

 the list of all registered GstTypeFindFactory. [transfer full][element-type Gst.TypeFindFactory]

gst_type_find_factory_get_extensions ()

gchar **	           gst_type_find_factory_get_extensions
                                                        (GstTypeFindFactory *factory);

Gets the extensions associated with a GstTypeFindFactory. The returned array should not be changed. If you need to change stuff in it, you should copy it using g_strdupv(). This function may return NULL to indicate a 0-length list.

factory :

 A GstTypeFindFactory

Returns :

 a NULL-terminated array of extensions associated with this factory. [transfer none][array zero-terminated=1][element-type utf8]

gst_type_find_factory_get_caps ()

GstCaps *	          gst_type_find_factory_get_caps      (GstTypeFindFactory *factory);

Gets the GstCaps associated with a typefind factory.

factory :

 A GstTypeFindFactory

Returns :

 the GstCaps associated with this factory. [transfer none]

gst_type_find_factory_call_function ()

void                gst_type_find_factory_call_function (GstTypeFindFactory *factory,
                                                         GstTypeFind *find);

Calls the GstTypeFindFunction associated with this factory.

factory :

 A GstTypeFindFactory

find :

 a properly setup GstTypeFind entry. The get_data and suggest_type members must be set. [transfer none]
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