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404 lines
11 KiB
C
404 lines
11 KiB
C
/* GStreamer
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* Copyright (C) 2003 Benjamin Otte <in7y118@public.uni-hamburg.de>
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*
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* gsttagsetter.c: interface for tag setting on elements
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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/**
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* SECTION:gsttagsetter
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* @short_description: Element interface that allows setting and retrieval
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* of media metadata
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*
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* Element interface that allows setting of media metadata.
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*
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* Elements that support changing a stream's metadata will implement this
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* interface. Examples of such elements are 'vorbisenc', 'theoraenc' and
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* 'id3v2mux'.
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*
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* If you just want to retrieve metadata in your application then all you
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* need to do is watch for tag messages on your pipeline's bus. This
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* interface is only for setting metadata, not for extracting it. To set tags
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* from the application, find tagsetter elements and set tags using e.g.
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* gst_tag_setter_merge_tags() or gst_tag_setter_add_tags(). Also consider
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* setting the #GstTagMergeMode that is used for tag events that arrive at the
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* tagsetter element (default mode is to keep existing tags).
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* The application should do that before the element goes to %GST_STATE_PAUSED.
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*
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* Elements implementing the #GstTagSetter interface often have to merge
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* any tags received from upstream and the tags set by the application via
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* the interface. This can be done like this:
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*
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* |[
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* GstTagMergeMode merge_mode;
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* const GstTagList *application_tags;
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* const GstTagList *event_tags;
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* GstTagSetter *tagsetter;
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* GstTagList *result;
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*
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* tagsetter = GST_TAG_SETTER (element);
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*
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* merge_mode = gst_tag_setter_get_tag_merge_mode (tagsetter);
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* application_tags = gst_tag_setter_get_tag_list (tagsetter);
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* event_tags = (const GstTagList *) element->event_tags;
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*
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* GST_LOG_OBJECT (tagsetter, "merging tags, merge mode = %d", merge_mode);
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* GST_LOG_OBJECT (tagsetter, "event tags: %" GST_PTR_FORMAT, event_tags);
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* GST_LOG_OBJECT (tagsetter, "set tags: %" GST_PTR_FORMAT, application_tags);
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*
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* result = gst_tag_list_merge (application_tags, event_tags, merge_mode);
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*
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* GST_LOG_OBJECT (tagsetter, "final tags: %" GST_PTR_FORMAT, result);
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* ]|
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*
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* Last reviewed on 2006-05-18 (0.10.6)
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include "gst_private.h"
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#include "gsttagsetter.h"
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#include <gobject/gvaluecollector.h>
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#include <string.h>
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static GQuark gst_tag_key;
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typedef struct
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{
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GstTagMergeMode mode;
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GstTagList *list;
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GMutex lock;
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} GstTagData;
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#define GST_TAG_DATA_LOCK(data) g_mutex_lock(&data->lock)
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#define GST_TAG_DATA_UNLOCK(data) g_mutex_unlock(&data->lock)
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G_DEFINE_INTERFACE_WITH_CODE (GstTagSetter, gst_tag_setter, GST_TYPE_ELEMENT,
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gst_tag_key = g_quark_from_static_string ("gst-tag-setter-data");
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);
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static void
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gst_tag_setter_default_init (GstTagSetterInterface * klass)
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{
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/* nothing to do here, it's a dummy interface */
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}
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static void
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gst_tag_data_free (gpointer p)
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{
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GstTagData *data = (GstTagData *) p;
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if (data->list)
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gst_tag_list_unref (data->list);
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g_mutex_clear (&data->lock);
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g_slice_free (GstTagData, data);
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}
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static GstTagData *
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gst_tag_setter_get_data (GstTagSetter * setter)
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{
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GstTagData *data;
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data = g_object_get_qdata (G_OBJECT (setter), gst_tag_key);
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if (!data) {
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/* make sure no other thread is creating a GstTagData at the same time */
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static GMutex create_mutex; /* no initialisation required */
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g_mutex_lock (&create_mutex);
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data = g_object_get_qdata (G_OBJECT (setter), gst_tag_key);
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if (!data) {
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data = g_slice_new (GstTagData);
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g_mutex_init (&data->lock);
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data->list = NULL;
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data->mode = GST_TAG_MERGE_KEEP;
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g_object_set_qdata_full (G_OBJECT (setter), gst_tag_key, data,
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gst_tag_data_free);
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}
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g_mutex_unlock (&create_mutex);
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}
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return data;
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}
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/**
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* gst_tag_setter_reset_tags:
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* @setter: a #GstTagSetter
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*
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* Reset the internal taglist. Elements should call this from within the
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* state-change handler.
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*/
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void
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gst_tag_setter_reset_tags (GstTagSetter * setter)
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{
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GstTagData *data;
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g_return_if_fail (GST_IS_TAG_SETTER (setter));
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data = gst_tag_setter_get_data (setter);
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GST_TAG_DATA_LOCK (data);
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if (data->list) {
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gst_tag_list_unref (data->list);
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data->list = NULL;
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}
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GST_TAG_DATA_UNLOCK (data);
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}
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/**
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* gst_tag_setter_merge_tags:
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* @setter: a #GstTagSetter
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* @list: a tag list to merge from
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* @mode: the mode to merge with
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*
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* Merges the given list into the setter's list using the given mode.
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*/
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void
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gst_tag_setter_merge_tags (GstTagSetter * setter, const GstTagList * list,
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GstTagMergeMode mode)
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{
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GstTagData *data;
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g_return_if_fail (GST_IS_TAG_SETTER (setter));
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g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
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g_return_if_fail (GST_IS_TAG_LIST (list));
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data = gst_tag_setter_get_data (setter);
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GST_TAG_DATA_LOCK (data);
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if (data->list == NULL) {
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if (mode != GST_TAG_MERGE_KEEP_ALL)
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data->list = gst_tag_list_copy (list);
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} else {
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gst_tag_list_insert (data->list, list, mode);
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}
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GST_TAG_DATA_UNLOCK (data);
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}
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/**
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* gst_tag_setter_add_tags:
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* @setter: a #GstTagSetter
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* @mode: the mode to use
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* @tag: tag to set
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* @...: more tag / value pairs to set
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*
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* Adds the given tag / value pairs on the setter using the given merge mode.
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* The list must be terminated with NULL.
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*/
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void
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gst_tag_setter_add_tags (GstTagSetter * setter, GstTagMergeMode mode,
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const gchar * tag, ...)
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{
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va_list args;
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g_return_if_fail (GST_IS_TAG_SETTER (setter));
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g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
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va_start (args, tag);
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gst_tag_setter_add_tag_valist (setter, mode, tag, args);
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va_end (args);
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}
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/**
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* gst_tag_setter_add_tag_values:
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* @setter: a #GstTagSetter
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* @mode: the mode to use
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* @tag: tag to set
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* @...: more tag / GValue pairs to set
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*
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* Adds the given tag / GValue pairs on the setter using the given merge mode.
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* The list must be terminated with NULL.
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*/
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void
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gst_tag_setter_add_tag_values (GstTagSetter * setter, GstTagMergeMode mode,
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const gchar * tag, ...)
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{
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va_list args;
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g_return_if_fail (GST_IS_TAG_SETTER (setter));
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g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
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va_start (args, tag);
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gst_tag_setter_add_tag_valist_values (setter, mode, tag, args);
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va_end (args);
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}
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/**
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* gst_tag_setter_add_tag_valist:
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* @setter: a #GstTagSetter
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* @mode: the mode to use
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* @tag: tag to set
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* @var_args: tag / value pairs to set
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*
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* Adds the given tag / value pairs on the setter using the given merge mode.
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* The list must be terminated with NULL.
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*/
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void
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gst_tag_setter_add_tag_valist (GstTagSetter * setter, GstTagMergeMode mode,
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const gchar * tag, va_list var_args)
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{
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GstTagData *data;
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g_return_if_fail (GST_IS_TAG_SETTER (setter));
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g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
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data = gst_tag_setter_get_data (setter);
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GST_TAG_DATA_LOCK (data);
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if (!data->list)
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data->list = gst_tag_list_new_empty ();
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gst_tag_list_add_valist (data->list, mode, tag, var_args);
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GST_TAG_DATA_UNLOCK (data);
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}
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/**
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* gst_tag_setter_add_tag_valist_values:
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* @setter: a #GstTagSetter
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* @mode: the mode to use
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* @tag: tag to set
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* @var_args: tag / GValue pairs to set
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*
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* Adds the given tag / GValue pairs on the setter using the given merge mode.
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* The list must be terminated with NULL.
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*/
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void
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gst_tag_setter_add_tag_valist_values (GstTagSetter * setter,
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GstTagMergeMode mode, const gchar * tag, va_list var_args)
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{
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GstTagData *data;
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g_return_if_fail (GST_IS_TAG_SETTER (setter));
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g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
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data = gst_tag_setter_get_data (setter);
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GST_TAG_DATA_LOCK (data);
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if (!data->list)
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data->list = gst_tag_list_new_empty ();
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gst_tag_list_add_valist_values (data->list, mode, tag, var_args);
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GST_TAG_DATA_UNLOCK (data);
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}
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/**
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* gst_tag_setter_add_tag_value:
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* @setter: a #GstTagSetter
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* @mode: the mode to use
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* @tag: tag to set
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* @value: GValue to set for the tag
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*
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* Adds the given tag / GValue pair on the setter using the given merge mode.
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*/
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void
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gst_tag_setter_add_tag_value (GstTagSetter * setter,
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GstTagMergeMode mode, const gchar * tag, const GValue * value)
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{
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GstTagData *data;
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g_return_if_fail (GST_IS_TAG_SETTER (setter));
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g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
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data = gst_tag_setter_get_data (setter);
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GST_TAG_DATA_LOCK (data);
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if (!data->list)
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data->list = gst_tag_list_new_empty ();
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gst_tag_list_add_value (data->list, mode, tag, value);
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GST_TAG_DATA_UNLOCK (data);
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}
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/**
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* gst_tag_setter_get_tag_list:
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* @setter: a #GstTagSetter
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*
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* Returns the current list of tags the setter uses. The list should not be
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* modified or freed.
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*
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* This function is not thread-safe.
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*
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* Returns: (transfer none): a current snapshot of the taglist used in the
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* setter or NULL if none is used.
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*/
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const GstTagList *
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gst_tag_setter_get_tag_list (GstTagSetter * setter)
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{
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g_return_val_if_fail (GST_IS_TAG_SETTER (setter), NULL);
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return gst_tag_setter_get_data (setter)->list;
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}
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/**
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* gst_tag_setter_set_tag_merge_mode:
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* @setter: a #GstTagSetter
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* @mode: The mode with which tags are added
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*
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* Sets the given merge mode that is used for adding tags from events to tags
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* specified by this interface. The default is #GST_TAG_MERGE_KEEP, which keeps
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* the tags set with this interface and discards tags from events.
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*/
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void
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gst_tag_setter_set_tag_merge_mode (GstTagSetter * setter, GstTagMergeMode mode)
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{
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GstTagData *data;
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g_return_if_fail (GST_IS_TAG_SETTER (setter));
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g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
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data = gst_tag_setter_get_data (setter);
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GST_TAG_DATA_LOCK (data);
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data->mode = mode;
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GST_TAG_DATA_UNLOCK (data);
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}
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/**
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* gst_tag_setter_get_tag_merge_mode:
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* @setter: a #GstTagSetter
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*
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* Queries the mode by which tags inside the setter are overwritten by tags
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* from events
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*
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* Returns: the merge mode used inside the element.
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*/
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GstTagMergeMode
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gst_tag_setter_get_tag_merge_mode (GstTagSetter * setter)
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{
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GstTagMergeMode mode;
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GstTagData *data;
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g_return_val_if_fail (GST_IS_TAG_SETTER (setter), GST_TAG_MERGE_UNDEFINED);
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data = gst_tag_setter_get_data (setter);
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GST_TAG_DATA_LOCK (data);
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mode = data->mode;
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GST_TAG_DATA_UNLOCK (data);
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return mode;
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}
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