GStreamer 1.0 Core Reference Manual: GstTypeFindFactory

## GstTypeFindFactory GstTypeFindFactory — Information about registered typefind functions |

## Functions

GList * | gst_type_find_factory_get_list ()
const gchar * const * | gst_type_find_factory_get_extensions ()
GstCaps * | gst_type_find_factory_get_caps ()
gboolean | gst_type_find_factory_has_function ()
void | gst_type_find_factory_call_function ()

## Types and Values

| GstTypeFindFactory

## Object Hierarchy

        GObject
        ╰── GInitiallyUnowned
            ╰── GstObject
                ╰── GstPluginFeature
                    ╰── GstTypeFindFactory

## Includes

    #include <gst/gst.h>

## 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 13. 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)

## Functions

### 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.

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 ()

    const gchar * const *
    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.

#### Parameters

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.

#### Parameters

factory | A GstTypeFindFactory |

#### Returns

the GstCaps associated with this factory.

[transfer none]

### gst_type_find_factory_has_function ()

    gboolean
    gst_type_find_factory_has_function (GstTypeFindFactory *factory);

Check whether the factory has a typefind function. Typefind factories without typefind functions are a last-effort fallback mechanism to e.g. assume a certain media type based on the file extension.

#### Parameters

factory | A GstTypeFindFactory |

#### Returns

TRUE if the factory has a typefind functions set, otherwise FALSE

### gst_type_find_factory_call_function ()

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

Calls the GstTypeFindFunction associated with this factory.

#### Parameters

factory | A GstTypeFindFactory |
find | a properly setup GstTypeFind entry. The get_data and suggest_type members must be set. | [transfer none]

## Types and Values

### GstTypeFindFactory

    typedef struct _GstTypeFindFactory GstTypeFindFactory;

Opaque object that stores information about a typefind function.