blob: 7ed457edf262758795c559e005f40cfaf85f7944 [file] [log] [blame]
/* GStreamer
* Copyright (C) 2003 Benjamin Otte <in7y118@public.uni-hamburg.de>
*
* gsttagsetter.c: interface for tag setting on elements
*
* 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:gsttagsetter
* @short_description: Element interface that allows setting and retrieval
* of media metadata
*
* Element interface that allows setting of media metadata.
*
* Elements that support changing a stream's metadata will implement this
* interface. Examples of such elements are 'vorbisenc', 'theoraenc' and
* 'id3v2mux'.
*
* If you just want to retrieve metadata in your application then all you
* need to do is watch for tag messages on your pipeline's bus. This
* interface is only for setting metadata, not for extracting it. To set tags
* from the application, find tagsetter elements and set tags using e.g.
* gst_tag_setter_merge_tags() or gst_tag_setter_add_tags(). Also consider
* setting the #GstTagMergeMode that is used for tag events that arrive at the
* tagsetter element (default mode is to keep existing tags).
* The application should do that before the element goes to %GST_STATE_PAUSED.
*
* Elements implementing the #GstTagSetter interface often have to merge
* any tags received from upstream and the tags set by the application via
* the interface. This can be done like this:
*
* |[
* GstTagMergeMode merge_mode;
* const GstTagList *application_tags;
* const GstTagList *event_tags;
* GstTagSetter *tagsetter;
* GstTagList *result;
*
* tagsetter = GST_TAG_SETTER (element);
*
* merge_mode = gst_tag_setter_get_tag_merge_mode (tagsetter);
* application_tags = gst_tag_setter_get_tag_list (tagsetter);
* event_tags = (const GstTagList *) element->event_tags;
*
* GST_LOG_OBJECT (tagsetter, "merging tags, merge mode = %d", merge_mode);
* GST_LOG_OBJECT (tagsetter, "event tags: %" GST_PTR_FORMAT, event_tags);
* GST_LOG_OBJECT (tagsetter, "set tags: %" GST_PTR_FORMAT, application_tags);
*
* result = gst_tag_list_merge (application_tags, event_tags, merge_mode);
*
* GST_LOG_OBJECT (tagsetter, "final tags: %" GST_PTR_FORMAT, result);
* ]|
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include "gst_private.h"
#include "gsttagsetter.h"
#include <gobject/gvaluecollector.h>
#include <string.h>
static GQuark gst_tag_key;
typedef struct
{
GstTagMergeMode mode;
GstTagList *list;
GMutex lock;
} GstTagData;
#define GST_TAG_DATA_LOCK(data) g_mutex_lock(&data->lock)
#define GST_TAG_DATA_UNLOCK(data) g_mutex_unlock(&data->lock)
G_DEFINE_INTERFACE_WITH_CODE (GstTagSetter, gst_tag_setter, GST_TYPE_ELEMENT,
gst_tag_key = g_quark_from_static_string ("gst-tag-setter-data");
);
static void
gst_tag_setter_default_init (GstTagSetterInterface * klass)
{
/* nothing to do here, it's a dummy interface */
}
static void
gst_tag_data_free (gpointer p)
{
GstTagData *data = (GstTagData *) p;
if (data->list)
gst_tag_list_unref (data->list);
g_mutex_clear (&data->lock);
g_slice_free (GstTagData, data);
}
static GstTagData *
gst_tag_setter_get_data (GstTagSetter * setter)
{
GstTagData *data;
data = g_object_get_qdata (G_OBJECT (setter), gst_tag_key);
if (!data) {
/* make sure no other thread is creating a GstTagData at the same time */
static GMutex create_mutex; /* no initialisation required */
g_mutex_lock (&create_mutex);
data = g_object_get_qdata (G_OBJECT (setter), gst_tag_key);
if (!data) {
data = g_slice_new (GstTagData);
g_mutex_init (&data->lock);
data->list = NULL;
data->mode = GST_TAG_MERGE_KEEP;
g_object_set_qdata_full (G_OBJECT (setter), gst_tag_key, data,
gst_tag_data_free);
}
g_mutex_unlock (&create_mutex);
}
return data;
}
/**
* gst_tag_setter_reset_tags:
* @setter: a #GstTagSetter
*
* Reset the internal taglist. Elements should call this from within the
* state-change handler.
*/
void
gst_tag_setter_reset_tags (GstTagSetter * setter)
{
GstTagData *data;
g_return_if_fail (GST_IS_TAG_SETTER (setter));
data = gst_tag_setter_get_data (setter);
GST_TAG_DATA_LOCK (data);
if (data->list) {
gst_tag_list_unref (data->list);
data->list = NULL;
}
GST_TAG_DATA_UNLOCK (data);
}
/**
* gst_tag_setter_merge_tags:
* @setter: a #GstTagSetter
* @list: a tag list to merge from
* @mode: the mode to merge with
*
* Merges the given list into the setter's list using the given mode.
*/
void
gst_tag_setter_merge_tags (GstTagSetter * setter, const GstTagList * list,
GstTagMergeMode mode)
{
GstTagData *data;
g_return_if_fail (GST_IS_TAG_SETTER (setter));
g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
g_return_if_fail (GST_IS_TAG_LIST (list));
data = gst_tag_setter_get_data (setter);
GST_TAG_DATA_LOCK (data);
if (data->list == NULL) {
if (mode != GST_TAG_MERGE_KEEP_ALL)
data->list = gst_tag_list_copy (list);
} else {
gst_tag_list_insert (data->list, list, mode);
}
GST_TAG_DATA_UNLOCK (data);
}
/**
* gst_tag_setter_add_tags:
* @setter: a #GstTagSetter
* @mode: the mode to use
* @tag: tag to set
* @...: more tag / value pairs to set
*
* Adds the given tag / value pairs on the setter using the given merge mode.
* The list must be terminated with %NULL.
*/
void
gst_tag_setter_add_tags (GstTagSetter * setter, GstTagMergeMode mode,
const gchar * tag, ...)
{
va_list args;
g_return_if_fail (GST_IS_TAG_SETTER (setter));
g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
va_start (args, tag);
gst_tag_setter_add_tag_valist (setter, mode, tag, args);
va_end (args);
}
/**
* gst_tag_setter_add_tag_values:
* @setter: a #GstTagSetter
* @mode: the mode to use
* @tag: tag to set
* @...: more tag / GValue pairs to set
*
* Adds the given tag / GValue pairs on the setter using the given merge mode.
* The list must be terminated with %NULL.
*/
void
gst_tag_setter_add_tag_values (GstTagSetter * setter, GstTagMergeMode mode,
const gchar * tag, ...)
{
va_list args;
g_return_if_fail (GST_IS_TAG_SETTER (setter));
g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
va_start (args, tag);
gst_tag_setter_add_tag_valist_values (setter, mode, tag, args);
va_end (args);
}
/**
* gst_tag_setter_add_tag_valist:
* @setter: a #GstTagSetter
* @mode: the mode to use
* @tag: tag to set
* @var_args: tag / value pairs to set
*
* Adds the given tag / value pairs on the setter using the given merge mode.
* The list must be terminated with %NULL.
*/
void
gst_tag_setter_add_tag_valist (GstTagSetter * setter, GstTagMergeMode mode,
const gchar * tag, va_list var_args)
{
GstTagData *data;
g_return_if_fail (GST_IS_TAG_SETTER (setter));
g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
data = gst_tag_setter_get_data (setter);
GST_TAG_DATA_LOCK (data);
if (!data->list)
data->list = gst_tag_list_new_empty ();
gst_tag_list_add_valist (data->list, mode, tag, var_args);
GST_TAG_DATA_UNLOCK (data);
}
/**
* gst_tag_setter_add_tag_valist_values:
* @setter: a #GstTagSetter
* @mode: the mode to use
* @tag: tag to set
* @var_args: tag / GValue pairs to set
*
* Adds the given tag / GValue pairs on the setter using the given merge mode.
* The list must be terminated with %NULL.
*/
void
gst_tag_setter_add_tag_valist_values (GstTagSetter * setter,
GstTagMergeMode mode, const gchar * tag, va_list var_args)
{
GstTagData *data;
g_return_if_fail (GST_IS_TAG_SETTER (setter));
g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
data = gst_tag_setter_get_data (setter);
GST_TAG_DATA_LOCK (data);
if (!data->list)
data->list = gst_tag_list_new_empty ();
gst_tag_list_add_valist_values (data->list, mode, tag, var_args);
GST_TAG_DATA_UNLOCK (data);
}
/**
* gst_tag_setter_add_tag_value:
* @setter: a #GstTagSetter
* @mode: the mode to use
* @tag: tag to set
* @value: GValue to set for the tag
*
* Adds the given tag / GValue pair on the setter using the given merge mode.
*/
void
gst_tag_setter_add_tag_value (GstTagSetter * setter,
GstTagMergeMode mode, const gchar * tag, const GValue * value)
{
GstTagData *data;
g_return_if_fail (GST_IS_TAG_SETTER (setter));
g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
data = gst_tag_setter_get_data (setter);
GST_TAG_DATA_LOCK (data);
if (!data->list)
data->list = gst_tag_list_new_empty ();
gst_tag_list_add_value (data->list, mode, tag, value);
GST_TAG_DATA_UNLOCK (data);
}
/**
* gst_tag_setter_get_tag_list:
* @setter: a #GstTagSetter
*
* Returns the current list of tags the setter uses. The list should not be
* modified or freed.
*
* This function is not thread-safe.
*
* Returns: (transfer none) (nullable): a current snapshot of the
* taglist used in the setter or %NULL if none is used.
*/
const GstTagList *
gst_tag_setter_get_tag_list (GstTagSetter * setter)
{
g_return_val_if_fail (GST_IS_TAG_SETTER (setter), NULL);
return gst_tag_setter_get_data (setter)->list;
}
/**
* gst_tag_setter_set_tag_merge_mode:
* @setter: a #GstTagSetter
* @mode: The mode with which tags are added
*
* Sets the given merge mode that is used for adding tags from events to tags
* specified by this interface. The default is #GST_TAG_MERGE_KEEP, which keeps
* the tags set with this interface and discards tags from events.
*/
void
gst_tag_setter_set_tag_merge_mode (GstTagSetter * setter, GstTagMergeMode mode)
{
GstTagData *data;
g_return_if_fail (GST_IS_TAG_SETTER (setter));
g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
data = gst_tag_setter_get_data (setter);
GST_TAG_DATA_LOCK (data);
data->mode = mode;
GST_TAG_DATA_UNLOCK (data);
}
/**
* gst_tag_setter_get_tag_merge_mode:
* @setter: a #GstTagSetter
*
* Queries the mode by which tags inside the setter are overwritten by tags
* from events
*
* Returns: the merge mode used inside the element.
*/
GstTagMergeMode
gst_tag_setter_get_tag_merge_mode (GstTagSetter * setter)
{
GstTagMergeMode mode;
GstTagData *data;
g_return_val_if_fail (GST_IS_TAG_SETTER (setter), GST_TAG_MERGE_UNDEFINED);
data = gst_tag_setter_get_data (setter);
GST_TAG_DATA_LOCK (data);
mode = data->mode;
GST_TAG_DATA_UNLOCK (data);
return mode;
}