gstreamer/gst/gsttag.c

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/* GStreamer
* Copyright (C) 2003 Benjamin Otte <in7y118@public.uni-hamburg.de>
*
* gsttag.c: tag support (aka metadata)
*
* 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., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include "gst_private.h"
#include "gsttag.h"
#include "gstinfo.h"
#include "gstvalue.h"
#include <gobject/gvaluecollector.h>
#include <string.h>
#define GST_TAG_IS_VALID(tag) (gst_tag_get_info (tag) != NULL)
typedef struct {
GType type; /* type the data is in */
gchar * nick; /* translated name */
gchar * blurb; /* translated description of type */
GstTagMergeFunc merge_func; /* functions to merge the values */
} GstTagInfo;
#define TAGLIST "taglist"
static GQuark gst_tag_list_quark;
static GMutex *__tag_mutex;
static GHashTable *__tags;
#define TAG_LOCK g_mutex_lock (__tag_mutex)
#define TAG_UNLOCK g_mutex_unlock (__tag_mutex)
void
_gst_tag_initialize (void)
{
gst_tag_list_quark = g_quark_from_static_string (TAGLIST);
__tag_mutex = g_mutex_new ();
__tags = g_hash_table_new (g_direct_hash, g_direct_equal);
gst_tag_register (GST_TAG_TITLE,
G_TYPE_STRING,
_("title"),
_("commonly used title"),
gst_tag_merge_strings_with_comma);
gst_tag_register (GST_TAG_ARTIST,
G_TYPE_STRING,
_("artist"),
_("person(s) resposible for the recording"),
gst_tag_merge_strings_with_comma);
gst_tag_register (GST_TAG_ALBUM,
G_TYPE_STRING,
_("album"),
_("album containing this data"),
gst_tag_merge_strings_with_comma);
gst_tag_register (GST_TAG_DATE,
G_TYPE_UINT, /* FIXME: own data type for dates? */
_("date"),
_("date the data was created in julien days"),
NULL);
gst_tag_register (GST_TAG_GENRE,
G_TYPE_STRING,
_("genre"),
_("genre this data belongs to"),
gst_tag_merge_strings_with_comma);
gst_tag_register (GST_TAG_COMMENT,
G_TYPE_STRING,
_("comment"),
_("free text commenting the data"),
gst_tag_merge_strings_with_comma);
gst_tag_register (GST_TAG_TRACK_NUMBER,
G_TYPE_UINT,
_("track number"),
_("track number inside a collection"),
gst_tag_merge_use_first);
gst_tag_register (GST_TAG_TRACK_COUNT,
G_TYPE_STRING,
_("track count"),
_("count of tracks inside collection this track belongs to"),
gst_tag_merge_use_first);
gst_tag_register (GST_TAG_LOCATION,
G_TYPE_STRING,
_("loccation"),
_("original location of file as a URI"),
gst_tag_merge_strings_with_comma);
gst_tag_register (GST_TAG_DESCRIPTION,
G_TYPE_STRING,
_("description"),
_("short text describing the content of the data"),
gst_tag_merge_strings_with_comma);
gst_tag_register (GST_TAG_VERSION,
G_TYPE_STRING,
_("version"),
_("version of this data"),
NULL);
gst_tag_register (GST_TAG_ISRC,
G_TYPE_STRING,
_("ISRC"),
_("International Standard Recording Code - see http://www.ifpi.org/isrc/"),
NULL);
gst_tag_register (GST_TAG_ORGANIZATION,
G_TYPE_STRING,
_("organization"),
_("organization"), /* FIXME */
gst_tag_merge_strings_with_comma);
gst_tag_register (GST_TAG_COPYRIGHT,
G_TYPE_STRING,
_("copyright"),
_("copyright notice of the data"),
NULL);
gst_tag_register (GST_TAG_CONTACT,
G_TYPE_STRING,
_("contact"),
_("contact information"),
gst_tag_merge_strings_with_comma);
gst_tag_register (GST_TAG_LICENSE,
G_TYPE_STRING,
_("license"),
_("license of data"),
NULL);
gst_tag_register (GST_TAG_PERFORMER,
G_TYPE_STRING,
_("performer"),
_("person(s) performing"),
gst_tag_merge_strings_with_comma);
gst_tag_register (GST_TAG_DURATION,
G_TYPE_UINT64,
_("duration"),
_("length in GStreamer time units (nanoseconds)"),
NULL);
gst_tag_register (GST_TAG_CODEC,
G_TYPE_STRING,
_("codec"),
_("codec the data is stored in"),
gst_tag_merge_strings_with_comma);
gst_tag_register (GST_TAG_MINIMUM_BITRATE,
G_TYPE_UINT,
_("minimum bitrate"),
_("minimum bitrate in bits/s"),
NULL);
gst_tag_register (GST_TAG_BITRATE,
G_TYPE_UINT,
_("bitrate"),
_("exact or average bitrate in bits/s"),
NULL);
gst_tag_register (GST_TAG_MAXIMUM_BITRATE,
G_TYPE_UINT,
_("maximum bitrate"),
_("maximum bitrate in bits/s"),
NULL);
}
/**
* gst_tag_merge_use_first:
* @dest: uninitialized GValue to store result in
* @src: GValue to copy from
*
* This is a convenience function for the func argument of gst_tag_register().
* It creates a copy of the first value from the list.
*/
void
gst_tag_merge_use_first (GValue *dest, const GValue *src)
{
const GValue *ret = gst_value_list_get_value (src, 0);
g_value_init (dest, G_VALUE_TYPE (ret));
g_value_copy (ret, dest);
}
/**
* gst_tag_merge_strings_with_comma:
* @dest: uninitialized GValue to store result in
* @src: GValue to copy from
*
* This is a convenience function for the func argument of gst_tag_register().
* It concatenates all given strings using a comma. The tag must be registered
* as a G_TYPE_STRING or this function will fail.
*/
void
gst_tag_merge_strings_with_comma (GValue *dest, const GValue *src)
{
GString *str;
gint i, count;
count = gst_value_list_get_size (src);
str = g_string_new (g_value_get_string (gst_value_list_get_value (src, 0)));
for (i = 1; i < count; i++) {
/* seperator between two string */
str = g_string_append (str, _(", "));
str = g_string_append (str, g_value_get_string (gst_value_list_get_value (src, 1)));
}
g_value_init (dest, G_TYPE_STRING);
g_value_set_string_take_ownership (dest, str->str);
g_string_free (str, FALSE);
}
static GstTagInfo *
gst_tag_lookup (GQuark entry)
{
GstTagInfo *ret;
TAG_LOCK;
ret = g_hash_table_lookup (__tags, GUINT_TO_POINTER (entry));
TAG_UNLOCK;
return ret;
}
/**
* gst_tag_register:
* @name: the name or identifier string
* @type: the type this data is in
* @nick: human-readable name
* @blurb: a human-readable description about this tag
* @func: function for merging multiple values of this tag
*
* Registers a new tag type for the use with GStreamer's type system. If a type
* with that name is already registered, that one is used.
* The old registration may have used a different type however. So don't rely
* on youre supplied values.
* If you know the type is already registered, use gst_tag_lookup instead.
* This function takes ownership of all supplied variables.
*/
void
gst_tag_register (gchar *name, GType type, gchar *nick, gchar *blurb,
GstTagMergeFunc func)
{
GQuark key;
GstTagInfo *info;
g_return_if_fail (name != NULL);
g_return_if_fail (nick != NULL);
g_return_if_fail (blurb != NULL);
g_return_if_fail (type != 0 && type != GST_TYPE_LIST);
key = g_quark_from_string (name);
info = gst_tag_lookup (key);
g_return_if_fail (info == NULL);
info = g_new (GstTagInfo, 1);
info->type = type;
info->nick = nick;
info->blurb = blurb;
info->merge_func = func;
TAG_LOCK;
g_hash_table_insert (__tags, GUINT_TO_POINTER (key), info);
TAG_UNLOCK;
}
/**
* gst_tag_exists:
* @tag: name of the tag
*
* Checks if the given type is already registered.
*
* Returns: TRUE if the type is already registered
*/
gboolean
gst_tag_exists (const gchar *tag)
{
g_return_val_if_fail (tag != NULL, FALSE);
return gst_tag_lookup (g_quark_from_string (tag)) != NULL;
}
/**
* gst_tag_get_type:
* @tag: the tag
*
* Gets the #GType used for this tag.
*
* Returns: the #GType of this tag
*/
GType
gst_tag_get_type (const gchar *tag)
{
GstTagInfo *info;
g_return_val_if_fail (tag != NULL, 0);
info = gst_tag_lookup (g_quark_from_string (tag));
g_return_val_if_fail (info != NULL, 0);
return info->type;
}
/**
* gst_tag_get_nick
* @tag: the tag
*
* Returns the human-readable name of this tag, You must not change or free
* this string.
*
* Returns: the human-readable name of this tag
*/
const gchar *
gst_tag_get_nick (const gchar *tag)
{
GstTagInfo *info;
g_return_val_if_fail (tag != NULL, NULL);
info = gst_tag_lookup (g_quark_from_string (tag));
g_return_val_if_fail (info != NULL, NULL);
return info->nick;
}
/**
* gst_tag_get_description:
* @tag: the tag
*
* Returns the human-readable description of this tag, You must not change or
* free this string.
*
* Return the human-readable description of this tag
*/
const gchar *
gst_tag_get_description (const gchar *tag)
{
GstTagInfo *info;
g_return_val_if_fail (tag != NULL, NULL);
info = gst_tag_lookup (g_quark_from_string (tag));
g_return_val_if_fail (info != NULL, NULL);
return info->blurb;
}
/**
* gst_tag_list_is_fixed:
* @tag: tag to check
*
* Checks if the given tag is fixed. A fixed tag can only contain one value.
* Unfixed tags can contain lists of values.
*
* Returns: TRUE, if the given tag is fixed.
*/
gboolean
gst_tag_is_fixed (const gchar *tag)
{
GstTagInfo *info;
g_return_val_if_fail (tag != NULL, FALSE);
info = gst_tag_lookup (g_quark_from_string (tag));
g_return_val_if_fail (info != NULL, FALSE);
return info->merge_func == NULL;
}
/**
* gst_tag_list_new:
*
* Creates a new empty GstTagList.
*
* Returns: An empty tag list
*/
GstTagList *
gst_tag_list_new (void)
{
return GST_TAG_LIST (gst_structure_new (TAGLIST, NULL));
}
/**
* gst_is_tag_list:
* @p: Object that might be a taglist
*
* Checks if the given pointer is a taglist.
*
* Returns: TRUE, if the given pointer is a taglist
*/
gboolean
gst_is_tag_list (gconstpointer p)
{
g_return_val_if_fail (p != NULL, FALSE);
return ((GstStructure *) p)->name == gst_tag_list_quark;
}
typedef struct {
GstStructure * list;
GstTagMergeMode mode;
} GstTagCopyData;
static void
gst_tag_list_add_value_internal (GstStructure *list, GstTagMergeMode mode, GQuark tag, GValue *value)
{
GstTagInfo *info = gst_tag_lookup (tag);
const GValue *value2;
g_assert (info != NULL);
if (info->merge_func && (value2 = gst_structure_id_get_value (list, tag)) != NULL) {
GValue dest = { 0, };
switch (mode) {
case GST_TAG_MERGE_REPLACE_ALL:
case GST_TAG_MERGE_REPLACE:
gst_structure_id_set_value (list, tag, value);
break;
case GST_TAG_MERGE_PREPEND:
gst_value_list_concat (&dest, value, value2);
gst_structure_id_set_value (list, tag, &dest);
g_value_unset (&dest);
break;
case GST_TAG_MERGE_APPEND:
gst_value_list_concat (&dest, value2, value);
gst_structure_id_set_value (list, tag, &dest);
g_value_unset (&dest);
break;
case GST_TAG_MERGE_KEEP:
case GST_TAG_MERGE_KEEP_ALL:
break;
default:
g_assert_not_reached ();
break;
}
} else {
switch (mode) {
case GST_TAG_MERGE_APPEND:
case GST_TAG_MERGE_KEEP:
if (gst_structure_id_get_value (list, tag) != NULL)
break;
/* fall through */
case GST_TAG_MERGE_REPLACE_ALL:
case GST_TAG_MERGE_REPLACE:
case GST_TAG_MERGE_PREPEND:
gst_structure_id_set_value (list, tag, value);
break;
case GST_TAG_MERGE_KEEP_ALL:
break;
default:
g_assert_not_reached ();
break;
}
}
}
static gboolean
gst_tag_list_copy_foreach (GQuark tag, GValue *value, gpointer user_data)
{
GstTagCopyData *copy = (GstTagCopyData *) user_data;
gst_tag_list_add_value_internal (copy->list, copy->mode, tag, value);
return TRUE;
}
/**
* gst_tag_list_insert:
* @into: list to merge into
* @from: list to merge from
* @mode: the mode to use
*
* Inserts the tags of the second list into the first list using the given mode.
*/
void
gst_tag_list_insert (GstTagList *into, const GstTagList *from, GstTagMergeMode mode)
{
GstTagCopyData data;
g_return_if_fail (GST_IS_TAG_LIST (into));
g_return_if_fail (GST_IS_TAG_LIST (from));
g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
data.list = (GstStructure *) into;
data.mode = mode;
if (mode == GST_TAG_MERGE_REPLACE_ALL) {
gst_structure_remove_all_fields (data.list);
}
gst_structure_foreach ((GstStructure *) from, gst_tag_list_copy_foreach, &data);
}
/**
* gst_tag_list_copy:
* @list: list to copy
*
* Copies a given #GstTagList.
*
* Returns: copy of the given list
*/
GstTagList *
gst_tag_list_copy (const GstTagList *list)
{
g_return_val_if_fail (GST_IS_TAG_LIST (list), NULL);
return GST_TAG_LIST (gst_structure_copy ((GstStructure *) list));
}
/**
* gst_tag_list_merge:
* @list1: first list to merge
* @list2: second list to merge
* @mode: the mode to use
*
* Merges the two given lists into a new list. If one of the lists is NULL, a
* copy of the other is returned. If both lists are NULL, NULL is returned.
*
* Returns: the new list
*/
GstTagList *
gst_tag_list_merge (const GstTagList *list1, const GstTagList *list2, GstTagMergeMode mode)
{
g_return_val_if_fail (list1 == NULL || GST_IS_TAG_LIST (list1), NULL);
g_return_val_if_fail (list2 == NULL || GST_IS_TAG_LIST (list2), NULL);
g_return_val_if_fail (GST_TAG_MODE_IS_VALID (mode), NULL);
if (!list1 && !list2) {
return NULL;
} else if (!list1) {
return gst_tag_list_copy (list2);
} else if (!list2) {
return gst_tag_list_copy (list1);
} else {
GstTagList *ret;
ret = gst_tag_list_copy (list1);
gst_tag_list_insert (ret, list2, mode);
return ret;
}
}
/**
* gst_tag_list_free:
* @list: the list to free
*
* Frees the given list and all associated values.
*/
void
gst_tag_list_free (GstTagList *list)
{
g_return_if_fail (GST_IS_TAG_LIST (list));
gst_structure_free ((GstStructure *) list);
}
/**
* gst_tag_list_get_tag_size:
* @list: a taglist
* @tag: the tag to query
*
* Checks how many value are stored in this tag list for the given tag.
*
* Returns: The number of tags stored
*/
guint
gst_tag_list_get_tag_size (const GstTagList *list, const gchar *tag)
{
const GValue *value;
g_return_val_if_fail (GST_IS_TAG_LIST (list), 0);
value = gst_structure_get_value ((GstStructure *) list, tag);
if (value == NULL)
return 0;
if (G_VALUE_TYPE (value) != GST_TYPE_LIST)
return 1;
return gst_value_list_get_size (value);
}
/**
* gst_tag_list_add:
* @list: list to set tags in
* @mode: the mode to use
* @tag: tag
* @...: values to set
*
* Sets the values for the given tags using the specified mode.
*/
void
gst_tag_list_add (GstTagList *list, GstTagMergeMode mode, const gchar *tag, ...)
{
va_list args;
g_return_if_fail (GST_IS_TAG_LIST (list));
g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
g_return_if_fail (tag != NULL);
va_start (args, tag);
gst_tag_list_add_valist (list, mode, tag, args);
va_end (args);
}
/**
* gst_tag_list_add_valist:
* @list: list to set tags in
* @mode: the mode to use
* @tag: tag
* @var_args: tag / value pairs to set
*
* Sets the values for the given tags using the specified mode.
*/
void
gst_tag_list_add_valist (GstTagList *list, GstTagMergeMode mode, const gchar *tag, va_list var_args)
{
GstTagInfo *info;
GQuark quark;
gchar *error = NULL;
g_return_if_fail (GST_IS_TAG_LIST (list));
g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
g_return_if_fail (tag != NULL);
while (tag != NULL) {
GValue value = { 0, };
quark = g_quark_from_string (tag);
info = gst_tag_lookup (quark);
g_return_if_fail (info != NULL);
g_value_init (&value, info->type);
G_VALUE_COLLECT (&value, var_args, 0, &error);
if (error) {
g_warning ("%s: %s", G_STRLOC, error);
g_free (error);
/* we purposely leak the value here, it might not be
* in a sane state if an error condition occoured
*/
return;
}
gst_tag_list_add_value_internal (list, mode, quark, &value);
g_value_unset (&value);
tag = va_arg (var_args, gchar *);
}
}
/**
* gst_tag_list_remove_tag:
* @list: list to remove tag from
* @tag: tag to remove
*
* Removes the goven tag from the taglist.
*/
void
gst_tag_list_remove_tag (GstTagList *list, const gchar *tag)
{
g_return_if_fail (GST_IS_TAG_LIST (list));
g_return_if_fail (tag != NULL);
gst_structure_remove_field ((GstStructure *) list, tag);
}
typedef struct {
GstTagForeachFunc func;
GstTagList * tag_list;
gpointer data;
} TagForeachData;
static int
structure_foreach_wrapper (GQuark field_id,
GValue *value, gpointer user_data)
{
TagForeachData *data = (TagForeachData *) user_data;
data->func (data->tag_list, g_quark_to_string (field_id), data->data);
return TRUE;
}
/**
* gst_tag_list_foreach:
* @list: list to iterate over
* @func: function to be called for each tag
* @user_data: user specified data
*
* Calls the given function for each tag inside the tag list. Note that if there
* is no tag, the function won't be called at all.
*/
void
gst_tag_list_foreach (GstTagList *list, GstTagForeachFunc func, gpointer user_data)
{
TagForeachData data;
g_return_if_fail (GST_IS_TAG_LIST (list));
g_return_if_fail (func != NULL);
data.func = func;
data.tag_list = list;
data.data = user_data;
gst_structure_foreach ((GstStructure *) list, structure_foreach_wrapper, &data);
}
/***** tag events *****/
/**
* gst_event_new_tag:
* @list: the tag list to put into the event or NULL for an empty list
*
* Creates a new tag event with the given list and takes ownership of it.
*
* Returns: a new tag event
*/
GstEvent *
gst_event_new_tag (GstTagList *list)
{
GstEvent *ret;
g_return_val_if_fail (list == NULL || GST_IS_TAG_LIST (list), NULL);
ret = gst_event_new (GST_EVENT_TAG);
if (!list)
list = gst_tag_list_new ();
ret->event_data.structure.structure = (GstStructure *) list;
return ret;
}
/**
* get_event_tag_get_list:
* @tag_event: a tagging #GstEvent
*
* Gets the taglist from a given tagging event.
*
* Returns: The #GstTagList of the event
*/
GstTagList *
gst_event_tag_get_list (GstEvent *tag_event)
{
g_return_val_if_fail (GST_IS_EVENT (tag_event), NULL);
g_return_val_if_fail (GST_EVENT_TYPE (tag_event) == GST_EVENT_TAG, NULL);
return GST_TAG_LIST (tag_event->event_data.structure.structure);
}
/**
* gst_tag_list_get_value_index:
* @list: a #GStTagList
* @tag: tag to read out
* @index: number of entry to read out
*
* Gets the value that is at the given index for the given tag in the given
* list.
*
* Returns: The GValue for the specified entry or NULL if the tag wasn't available
* or the tag doesn't have as many entries
*/
G_CONST_RETURN GValue *
gst_tag_list_get_value_index (const GstTagList *list, const gchar *tag, guint index)
{
const GValue *value;
g_return_val_if_fail (GST_IS_TAG_LIST (list), NULL);
g_return_val_if_fail (tag != NULL, NULL);
value = gst_structure_get_value ((GstStructure *) list, tag);
if (value == NULL) return NULL;
if (GST_VALUE_HOLDS_LIST (value)) {
if (index >= gst_value_list_get_size (value)) return NULL;
return gst_value_list_get_value (value, index);
} else {
if (index > 0) return NULL;
return value;
}
}
/**
* gst_tag_list_copy_value:
* @dest: uninitialized #GValue to copy into
* @list: list to get the tag from
* @tag: tag to read out
*
* Copies the contents for the given tag into the value, merging multiple values
* into one if multiple values are associated with the tag.
* You must g_value_unset() the value after use.
*
* Returns: TRUE, if a value was copied, FALSE if the tag didn't exist in the
* given list.
*/
gboolean
gst_tag_list_copy_value (GValue *dest, const GstTagList *list, const gchar *tag)
{
const GValue *src;
g_return_val_if_fail (GST_IS_TAG_LIST (list), FALSE);
g_return_val_if_fail (tag != NULL, FALSE);
g_return_val_if_fail (dest != NULL, FALSE);
g_return_val_if_fail (G_VALUE_TYPE (dest) == 0, FALSE);
src = gst_structure_get_value ((GstStructure *) list, tag);
if (!src) return FALSE;
if (G_VALUE_TYPE (src) == GST_TYPE_LIST) {
GstTagInfo *info = gst_tag_lookup (g_quark_from_string (tag));
/* must be there or lists aren't allowed */
g_assert (info->merge_func);
info->merge_func (dest, src);
} else {
g_value_init (dest, G_VALUE_TYPE (src));
g_value_copy (src, dest);
}
return TRUE;
}
/***** evil macros to get all the gst_tag_list_get_*() functions right *****/
#define TAG_MERGE_FUNCS(name,type) \
gboolean \
gst_tag_list_get_ ## name (const GstTagList *list, const gchar *tag, \
type *value) \
{ \
GValue v = { 0, }; \
\
g_return_val_if_fail (GST_IS_TAG_LIST (list), FALSE); \
g_return_val_if_fail (tag != NULL, FALSE); \
g_return_val_if_fail (value != NULL, FALSE); \
\
if (!gst_tag_list_copy_value (&v, list, tag)) \
return FALSE; \
*value = COPY_FUNC (g_value_get_ ## name (&v)); \
g_value_unset (&v); \
return TRUE; \
} \
\
gboolean \
gst_tag_list_get_ ## name ## _index (const GstTagList *list, const gchar *tag, \
guint index, type *value) \
{ \
const GValue *v; \
\
g_return_val_if_fail (GST_IS_TAG_LIST (list), FALSE); \
g_return_val_if_fail (tag != NULL, FALSE); \
g_return_val_if_fail (value != NULL, FALSE); \
\
if ((v = gst_tag_list_get_value_index (list, tag, index)) == NULL) \
return FALSE; \
*value = COPY_FUNC (g_value_get_ ## name (v)); \
return TRUE; \
}
#define COPY_FUNC /**/
TAG_MERGE_FUNCS (char, gchar)
TAG_MERGE_FUNCS (uchar, guchar)
TAG_MERGE_FUNCS (boolean, gboolean)
TAG_MERGE_FUNCS (int, gint)
TAG_MERGE_FUNCS (uint, guint)
TAG_MERGE_FUNCS (long, glong)
TAG_MERGE_FUNCS (ulong, gulong)
TAG_MERGE_FUNCS (int64, gint64)
TAG_MERGE_FUNCS (uint64, guint64)
TAG_MERGE_FUNCS (float, gfloat)
TAG_MERGE_FUNCS (double, gdouble)
#undef COPY_FUNC
#define COPY_FUNC g_strdup
TAG_MERGE_FUNCS (string, gchar *)