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".

The following 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.

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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;
    };

## 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][nullable]

### 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.