gst/gstmeta.c - imx-gstreamer - Git at Google

 /* GStreamer
  * Copyright (C) 2011 Wim Taymans <wim.taymans@gmail.com>
  *
  * gstmeta.c: metadata operations
  *
  * 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., 51 Franklin St, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */

 /**
  * SECTION:gstmeta
  * @title: GstMeta
  * @short_description: Buffer metadata
  *
  * 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 "gstbuffer.h"
 #include "gstmeta.h"
 #include "gstinfo.h"
 #include "gstutils.h"

 static GHashTable *metainfo = NULL;
 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_api_type_has_tag:
  * @api: an API
  * @tag: the tag to check
  *
  * Check if @api was registered with @tag.
  *
  * 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 (GType api, const gchar * impl, gsize size,
     GstMetaInitFunction init_func, GstMetaFreeFunction free_func,
     GstMetaTransformFunction transform_func)
 {
   GstMetaInfo *info;
   GType type;

   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 = api;
   info->type = type;
   info->size = size;
   info->init_func = init_func;
   info->free_func = free_func;
   info->transform_func = transform_func;

   GST_CAT_DEBUG (GST_CAT_META,
       "register \"%s\" implementing \"%s\" of size %" G_GSIZE_FORMAT, impl,
       g_type_name (api), size);

   g_rw_lock_writer_lock (&lock);
   g_hash_table_insert (metainfo, (gpointer) impl, (gpointer) info);
   g_rw_lock_writer_unlock (&lock);

   return info;
 }

 /**
  * gst_meta_get_info:
  * @impl: the name
  *
  * Lookup a previously registered meta info structure by its implementation name
  * @impl.
  *
  * Returns: (transfer none) (nullable): a #GstMetaInfo with @impl, or
  * %NULL when no such metainfo exists.
  */
 const GstMetaInfo *
 gst_meta_get_info (const gchar * impl)
 {
   GstMetaInfo *info;

   g_return_val_if_fail (impl != NULL, NULL);

   g_rw_lock_reader_lock (&lock);
   info = g_hash_table_lookup (metainfo, impl);
   g_rw_lock_reader_unlock (&lock);

   return info;
 }
	/* GStreamer
	* Copyright (C) 2011 Wim Taymans <wim.taymans@gmail.com>
	*
	* gstmeta.c: metadata operations
	*
	* 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., 51 Franklin St, Fifth Floor,
	* Boston, MA 02110-1301, USA.
	*/

	/**
	* SECTION:gstmeta
	* @title: GstMeta
	* @short_description: Buffer metadata
	*
	* 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 "gstbuffer.h"
	#include "gstmeta.h"
	#include "gstinfo.h"
	#include "gstutils.h"

	static GHashTable *metainfo = NULL;
	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_api_type_has_tag:
	* @api: an API
	* @tag: the tag to check
	*
	* Check if @api was registered with @tag.
	*
	* 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 (GType api, const gchar * impl, gsize size,
	GstMetaInitFunction init_func, GstMetaFreeFunction free_func,
	GstMetaTransformFunction transform_func)
	{
	GstMetaInfo *info;
	GType type;

	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 = api;
	info->type = type;
	info->size = size;
	info->init_func = init_func;
	info->free_func = free_func;
	info->transform_func = transform_func;

	GST_CAT_DEBUG (GST_CAT_META,
	"register \"%s\" implementing \"%s\" of size %" G_GSIZE_FORMAT, impl,
	g_type_name (api), size);

	g_rw_lock_writer_lock (&lock);
	g_hash_table_insert (metainfo, (gpointer) impl, (gpointer) info);
	g_rw_lock_writer_unlock (&lock);

	return info;
	}

	/**
	* gst_meta_get_info:
	* @impl: the name
	*
	* Lookup a previously registered meta info structure by its implementation name
	* @impl.
	*
	* Returns: (transfer none) (nullable): a #GstMetaInfo with @impl, or
	* %NULL when no such metainfo exists.
	*/
	const GstMetaInfo *
	gst_meta_get_info (const gchar * impl)
	{
	GstMetaInfo *info;

	g_return_val_if_fail (impl != NULL, NULL);

	g_rw_lock_reader_lock (&lock);
	info = g_hash_table_lookup (metainfo, impl);
	g_rw_lock_reader_unlock (&lock);

	return info;
	}