*
* 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.
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
*/
/**
* SECTION:gstmeta
+ * @title: GstMeta
* @short_description: Buffer metadata
*
- * Last reviewed on December 17th, 2009 (0.10.26)
+ * The #GstMeta structure should be included as the first member of a #GstBuffer
+ * metadata structure. The structure defines the API of the metadata and should
+ * be accessible to all elements using the metadata.
+ *
+ * A metadata API is registered with gst_meta_api_type_register() which takes a
+ * name for the metadata API and some tags associated with the metadata.
+ * With gst_meta_api_type_has_tag() one can check if a certain metadata API
+ * contains a given tag.
+ *
+ * Multiple implementations of a metadata API can be registered.
+ * To implement a metadata API, gst_meta_register() should be used. This
+ * function takes all parameters needed to create, free and transform metadata
+ * along with the size of the metadata. The function returns a #GstMetaInfo
+ * structure that contains the information for the implementation of the API.
+ *
+ * A specific implementation can be retrieved by name with gst_meta_get_info().
+ *
+ * See #GstBuffer for how the metadata can be added, retrieved and removed from
+ * buffers.
*/
#include "gst_private.h"
#include "gstutils.h"
static GHashTable *metainfo = NULL;
-static GStaticRWLock lock = G_STATIC_RW_LOCK_INIT;
+static GRWLock lock;
+
+GQuark _gst_meta_transform_copy;
+GQuark _gst_meta_tag_memory;
void
_priv_gst_meta_initialize (void)
{
+ g_rw_lock_init (&lock);
metainfo = g_hash_table_new (g_str_hash, g_str_equal);
+
+ _gst_meta_transform_copy = g_quark_from_static_string ("gst-copy");
+ _gst_meta_tag_memory = g_quark_from_static_string ("memory");
+}
+
+/**
+ * gst_meta_api_type_register:
+ * @api: an API to register
+ * @tags: (array zero-terminated=1): tags for @api
+ *
+ * Register and return a GType for the @api and associate it with
+ * @tags.
+ *
+ * Returns: a unique GType for @api.
+ */
+GType
+gst_meta_api_type_register (const gchar * api, const gchar ** tags)
+{
+ GType type;
+
+ g_return_val_if_fail (api != NULL, 0);
+ g_return_val_if_fail (tags != NULL, 0);
+
+ GST_CAT_DEBUG (GST_CAT_META, "register API \"%s\"", api);
+ type = g_pointer_type_register_static (api);
+
+ if (type != 0) {
+ gint i;
+
+ for (i = 0; tags[i]; i++) {
+ GST_CAT_DEBUG (GST_CAT_META, " adding tag \"%s\"", tags[i]);
+ g_type_set_qdata (type, g_quark_from_string (tags[i]),
+ GINT_TO_POINTER (TRUE));
+ }
+ }
+
+ g_type_set_qdata (type, g_quark_from_string ("tags"),
+ g_strdupv ((gchar **) tags));
+
+ return type;
}
/**
- * gst_meta_register_info:
- * @info: a #GstMetaInfo
+ * gst_meta_api_type_has_tag:
+ * @api: an API
+ * @tag: the tag to check
*
- * Register a #GstMetaInfo. The same @info can be retrieved later with
- * gst_meta_get_info() by using @impl as the key.
+ * Check if @api was registered with @tag.
*
- * Returns: a #GstMetaInfo that can be used to access metadata.
+ * Returns: %TRUE if @api was registered with @tag.
+ */
+gboolean
+gst_meta_api_type_has_tag (GType api, GQuark tag)
+{
+ g_return_val_if_fail (api != 0, FALSE);
+ g_return_val_if_fail (tag != 0, FALSE);
+
+ return g_type_get_qdata (api, tag) != NULL;
+}
+
+/**
+ * gst_meta_api_type_get_tags:
+ * @api: an API
+ *
+ * Returns: (transfer none) (array zero-terminated=1) (element-type utf8): an array of tags as strings.
+ *
+ * Since: 1.2
+ */
+const gchar *const *
+gst_meta_api_type_get_tags (GType api)
+{
+ const gchar **tags;
+ g_return_val_if_fail (api != 0, FALSE);
+
+ tags = g_type_get_qdata (api, g_quark_from_string ("tags"));
+
+ if (!tags[0])
+ return NULL;
+
+ return (const gchar * const *) tags;
+}
+
+/**
+ * gst_meta_register:
+ * @api: the type of the #GstMeta API
+ * @impl: the name of the #GstMeta implementation
+ * @size: the size of the #GstMeta structure
+ * @init_func: (scope async): a #GstMetaInitFunction
+ * @free_func: (scope async): a #GstMetaFreeFunction
+ * @transform_func: (scope async): a #GstMetaTransformFunction
+ *
+ * Register a new #GstMeta implementation.
+ *
+ * The same @info can be retrieved later with gst_meta_get_info() by using
+ * @impl as the key.
+ *
+ * Returns: (transfer none) (nullable): a #GstMetaInfo that can be used to
+ * access metadata.
*/
const GstMetaInfo *
-gst_meta_register (const gchar * api, const gchar * impl, gsize size,
+gst_meta_register (GType api, const gchar * impl, gsize size,
GstMetaInitFunction init_func, GstMetaFreeFunction free_func,
- GstMetaCopyFunction copy_func, GstMetaTransformFunction transform_func)
+ GstMetaTransformFunction transform_func)
{
GstMetaInfo *info;
+ GType type;
- g_return_val_if_fail (api != NULL, NULL);
+ g_return_val_if_fail (api != 0, NULL);
g_return_val_if_fail (impl != NULL, NULL);
g_return_val_if_fail (size != 0, NULL);
+ if (init_func == NULL)
+ g_critical ("Registering meta implementation '%s' without init function",
+ impl);
+
+ /* first try to register the implementation name. It's possible
+ * that this fails because it was already registered. Don't warn,
+ * glib did this for us already. */
+ type = g_pointer_type_register_static (impl);
+ if (type == 0)
+ return NULL;
+
info = g_slice_new (GstMetaInfo);
- info->api = g_quark_from_string (api);
- info->type = g_pointer_type_register_static (impl);
+ info->api = api;
+ info->type = type;
info->size = size;
info->init_func = init_func;
info->free_func = free_func;
- info->copy_func = copy_func;
info->transform_func = transform_func;
- GST_DEBUG ("register \"%s\" implementing \"%s\" of size %" G_GSIZE_FORMAT,
- api, impl, size);
+ GST_CAT_DEBUG (GST_CAT_META,
+ "register \"%s\" implementing \"%s\" of size %" G_GSIZE_FORMAT, impl,
+ g_type_name (api), size);
- g_static_rw_lock_writer_lock (&lock);
+ g_rw_lock_writer_lock (&lock);
g_hash_table_insert (metainfo, (gpointer) impl, (gpointer) info);
- g_static_rw_lock_writer_unlock (&lock);
+ g_rw_lock_writer_unlock (&lock);
return info;
}
* gst_meta_get_info:
* @impl: the name
*
- * Lookup a previously registered meta info structure by its implementor name
+ * Lookup a previously registered meta info structure by its implementation name
* @impl.
*
- * Returns: a #GstMetaInfo with @impl or #NULL when no such metainfo
- * exists.
+ * Returns: (transfer none) (nullable): a #GstMetaInfo with @impl, or
+ * %NULL when no such metainfo exists.
*/
const GstMetaInfo *
gst_meta_get_info (const gchar * impl)
g_return_val_if_fail (impl != NULL, NULL);
- g_static_rw_lock_reader_lock (&lock);
+ g_rw_lock_reader_lock (&lock);
info = g_hash_table_lookup (metainfo, impl);
- g_static_rw_lock_reader_unlock (&lock);
+ g_rw_lock_reader_unlock (&lock);
return info;
}
+
+/**
+ * gst_meta_get_seqnum:
+ * @meta: a #GstMeta
+ *
+ * Gets seqnum for this meta.
+ *
+ * Since: 1.16
+ */
+guint64
+gst_meta_get_seqnum (const GstMeta * meta)
+{
+ GstMetaItem *meta_item;
+ guint8 *p;
+
+ g_return_val_if_fail (meta != NULL, 0);
+
+ p = (guint8 *) meta;
+ p -= G_STRUCT_OFFSET (GstMetaItem, meta);
+ meta_item = (GstMetaItem *) p;
+ return meta_item->seq_num;
+}
+
+/**
+ * gst_meta_compare_seqnum:
+ * @meta1: a #GstMeta
+ * @meta2: a #GstMeta
+ *
+ * Meta sequence number compare function. Can be used as #GCompareFunc
+ * or a #GCompareDataFunc.
+ *
+ * Returns: a negative number if @meta1 comes before @meta2, 0 if both metas
+ * have an equal sequence number, or a positive integer if @meta1 comes
+ * after @meta2.
+ *
+ * Since: 1.16
+ */
+gint
+gst_meta_compare_seqnum (const GstMeta * meta1, const GstMeta * meta2)
+{
+ guint64 seqnum1 = gst_meta_get_seqnum (meta1);
+ guint64 seqnum2 = gst_meta_get_seqnum (meta2);
+
+ if (seqnum1 == seqnum2)
+ return 0;
+
+ return (seqnum1 < seqnum2) ? -1 : 1;
+}
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