2 * Copyright (C) 2003 Benjamin Otte <in7y118@public.uni-hamburg.de>
4 * gsttagsetter.c: interface for tag setting on elements
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Library General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Library General Public License for more details.
16 * You should have received a copy of the GNU Library General Public
17 * License along with this library; if not, write to the
18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 * Boston, MA 02111-1307, USA.
23 * SECTION:gsttagsetter
24 * @short_description: Element interface that allows setting and retrieval
27 * Element interface that allows setting of media metadata.
29 * Elements that support changing a stream's metadata will implement this
30 * interface. Examples of such elements are 'vorbisenc', 'theoraenc' and
33 * If you just want to retrieve metadata in your application then all you
34 * need to do is watch for tag messages on your pipeline's bus. This
35 * interface is only for setting metadata, not for extracting it. To set tags
36 * from the application, find tagsetter elements and set tags using e.g.
37 * gst_tag_setter_merge_tags() or gst_tag_setter_add_tags(). Also consider
38 * setting the #GstTagMergeMode that is used for tag events that arrive at the
39 * tagsetter element (default mode is to keep existing tags).
40 * The application should do that before the element goes to %GST_STATE_PAUSED.
42 * Elements implementing the #GstTagSetter interface often have to merge
43 * any tags received from upstream and the tags set by the application via
44 * the interface. This can be done like this:
47 * GstTagMergeMode merge_mode;
48 * const GstTagList *application_tags;
49 * const GstTagList *event_tags;
50 * GstTagSetter *tagsetter;
53 * tagsetter = GST_TAG_SETTER (element);
55 * merge_mode = gst_tag_setter_get_tag_merge_mode (tagsetter);
56 * application_tags = gst_tag_setter_get_tag_list (tagsetter);
57 * event_tags = (const GstTagList *) element->event_tags;
59 * GST_LOG_OBJECT (tagsetter, "merging tags, merge mode = %d", merge_mode);
60 * GST_LOG_OBJECT (tagsetter, "event tags: %" GST_PTR_FORMAT, event_tags);
61 * GST_LOG_OBJECT (tagsetter, "set tags: %" GST_PTR_FORMAT, application_tags);
63 * result = gst_tag_list_merge (application_tags, event_tags, merge_mode);
65 * GST_LOG_OBJECT (tagsetter, "final tags: %" GST_PTR_FORMAT, result);
68 * Last reviewed on 2006-05-18 (0.10.6)
75 #include "gst_private.h"
76 #include "gsttagsetter.h"
77 #include <gobject/gvaluecollector.h>
80 static GQuark gst_tag_key;
89 #define GST_TAG_DATA_LOCK(data) g_mutex_lock(&data->lock)
90 #define GST_TAG_DATA_UNLOCK(data) g_mutex_unlock(&data->lock)
92 G_DEFINE_INTERFACE_WITH_CODE (GstTagSetter, gst_tag_setter, GST_TYPE_ELEMENT,
93 gst_tag_key = g_quark_from_static_string ("gst-tag-setter-data");
97 gst_tag_setter_default_init (GstTagSetterInterface * klass)
99 /* nothing to do here, it's a dummy interface */
103 gst_tag_data_free (gpointer p)
105 GstTagData *data = (GstTagData *) p;
108 gst_tag_list_unref (data->list);
110 g_mutex_clear (&data->lock);
112 g_slice_free (GstTagData, data);
116 gst_tag_setter_get_data (GstTagSetter * setter)
120 data = g_object_get_qdata (G_OBJECT (setter), gst_tag_key);
122 /* make sure no other thread is creating a GstTagData at the same time */
123 static GMutex create_mutex; /* no initialisation required */
125 g_mutex_lock (&create_mutex);
127 data = g_object_get_qdata (G_OBJECT (setter), gst_tag_key);
129 data = g_slice_new (GstTagData);
130 g_mutex_init (&data->lock);
132 data->mode = GST_TAG_MERGE_KEEP;
133 g_object_set_qdata_full (G_OBJECT (setter), gst_tag_key, data,
137 g_mutex_unlock (&create_mutex);
144 * gst_tag_setter_reset_tags:
145 * @setter: a #GstTagSetter
147 * Reset the internal taglist. Elements should call this from within the
148 * state-change handler.
151 gst_tag_setter_reset_tags (GstTagSetter * setter)
155 g_return_if_fail (GST_IS_TAG_SETTER (setter));
157 data = gst_tag_setter_get_data (setter);
159 GST_TAG_DATA_LOCK (data);
161 gst_tag_list_unref (data->list);
164 GST_TAG_DATA_UNLOCK (data);
168 * gst_tag_setter_merge_tags:
169 * @setter: a #GstTagSetter
170 * @list: a tag list to merge from
171 * @mode: the mode to merge with
173 * Merges the given list into the setter's list using the given mode.
176 gst_tag_setter_merge_tags (GstTagSetter * setter, const GstTagList * list,
177 GstTagMergeMode mode)
181 g_return_if_fail (GST_IS_TAG_SETTER (setter));
182 g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
183 g_return_if_fail (GST_IS_TAG_LIST (list));
185 data = gst_tag_setter_get_data (setter);
187 GST_TAG_DATA_LOCK (data);
188 if (data->list == NULL) {
189 if (mode != GST_TAG_MERGE_KEEP_ALL)
190 data->list = gst_tag_list_copy (list);
192 gst_tag_list_insert (data->list, list, mode);
194 GST_TAG_DATA_UNLOCK (data);
198 * gst_tag_setter_add_tags:
199 * @setter: a #GstTagSetter
200 * @mode: the mode to use
202 * @...: more tag / value pairs to set
204 * Adds the given tag / value pairs on the setter using the given merge mode.
205 * The list must be terminated with NULL.
208 gst_tag_setter_add_tags (GstTagSetter * setter, GstTagMergeMode mode,
209 const gchar * tag, ...)
213 g_return_if_fail (GST_IS_TAG_SETTER (setter));
214 g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
216 va_start (args, tag);
217 gst_tag_setter_add_tag_valist (setter, mode, tag, args);
222 * gst_tag_setter_add_tag_values:
223 * @setter: a #GstTagSetter
224 * @mode: the mode to use
226 * @...: more tag / GValue pairs to set
228 * Adds the given tag / GValue pairs on the setter using the given merge mode.
229 * The list must be terminated with NULL.
232 gst_tag_setter_add_tag_values (GstTagSetter * setter, GstTagMergeMode mode,
233 const gchar * tag, ...)
237 g_return_if_fail (GST_IS_TAG_SETTER (setter));
238 g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
240 va_start (args, tag);
241 gst_tag_setter_add_tag_valist_values (setter, mode, tag, args);
246 * gst_tag_setter_add_tag_valist:
247 * @setter: a #GstTagSetter
248 * @mode: the mode to use
250 * @var_args: tag / value pairs to set
252 * Adds the given tag / value pairs on the setter using the given merge mode.
253 * The list must be terminated with NULL.
256 gst_tag_setter_add_tag_valist (GstTagSetter * setter, GstTagMergeMode mode,
257 const gchar * tag, va_list var_args)
261 g_return_if_fail (GST_IS_TAG_SETTER (setter));
262 g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
264 data = gst_tag_setter_get_data (setter);
266 GST_TAG_DATA_LOCK (data);
268 data->list = gst_tag_list_new_empty ();
270 gst_tag_list_add_valist (data->list, mode, tag, var_args);
272 GST_TAG_DATA_UNLOCK (data);
276 * gst_tag_setter_add_tag_valist_values:
277 * @setter: a #GstTagSetter
278 * @mode: the mode to use
280 * @var_args: tag / GValue pairs to set
282 * Adds the given tag / GValue pairs on the setter using the given merge mode.
283 * The list must be terminated with NULL.
286 gst_tag_setter_add_tag_valist_values (GstTagSetter * setter,
287 GstTagMergeMode mode, const gchar * tag, va_list var_args)
291 g_return_if_fail (GST_IS_TAG_SETTER (setter));
292 g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
294 data = gst_tag_setter_get_data (setter);
296 GST_TAG_DATA_LOCK (data);
299 data->list = gst_tag_list_new_empty ();
301 gst_tag_list_add_valist_values (data->list, mode, tag, var_args);
303 GST_TAG_DATA_UNLOCK (data);
307 * gst_tag_setter_add_tag_value:
308 * @setter: a #GstTagSetter
309 * @mode: the mode to use
311 * @value: GValue to set for the tag
313 * Adds the given tag / GValue pair on the setter using the given merge mode.
316 gst_tag_setter_add_tag_value (GstTagSetter * setter,
317 GstTagMergeMode mode, const gchar * tag, const GValue * value)
321 g_return_if_fail (GST_IS_TAG_SETTER (setter));
322 g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
324 data = gst_tag_setter_get_data (setter);
326 GST_TAG_DATA_LOCK (data);
329 data->list = gst_tag_list_new_empty ();
331 gst_tag_list_add_value (data->list, mode, tag, value);
333 GST_TAG_DATA_UNLOCK (data);
337 * gst_tag_setter_get_tag_list:
338 * @setter: a #GstTagSetter
340 * Returns the current list of tags the setter uses. The list should not be
343 * This function is not thread-safe.
345 * Returns: (transfer none): a current snapshot of the taglist used in the
346 * setter or NULL if none is used.
349 gst_tag_setter_get_tag_list (GstTagSetter * setter)
351 g_return_val_if_fail (GST_IS_TAG_SETTER (setter), NULL);
353 return gst_tag_setter_get_data (setter)->list;
357 * gst_tag_setter_set_tag_merge_mode:
358 * @setter: a #GstTagSetter
359 * @mode: The mode with which tags are added
361 * Sets the given merge mode that is used for adding tags from events to tags
362 * specified by this interface. The default is #GST_TAG_MERGE_KEEP, which keeps
363 * the tags set with this interface and discards tags from events.
366 gst_tag_setter_set_tag_merge_mode (GstTagSetter * setter, GstTagMergeMode mode)
370 g_return_if_fail (GST_IS_TAG_SETTER (setter));
371 g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
373 data = gst_tag_setter_get_data (setter);
375 GST_TAG_DATA_LOCK (data);
377 GST_TAG_DATA_UNLOCK (data);
381 * gst_tag_setter_get_tag_merge_mode:
382 * @setter: a #GstTagSetter
384 * Queries the mode by which tags inside the setter are overwritten by tags
387 * Returns: the merge mode used inside the element.
390 gst_tag_setter_get_tag_merge_mode (GstTagSetter * setter)
392 GstTagMergeMode mode;
395 g_return_val_if_fail (GST_IS_TAG_SETTER (setter), GST_TAG_MERGE_UNDEFINED);
397 data = gst_tag_setter_get_data (setter);
399 GST_TAG_DATA_LOCK (data);
401 GST_TAG_DATA_UNLOCK (data);