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;
90 gst_tag_setter_get_type (void)
92 static volatile gsize tag_setter_type = 0;
94 if (g_once_init_enter (&tag_setter_type)) {
96 static const GTypeInfo tag_setter_info = {
97 sizeof (GstTagSetterIFace), /* class_size */
99 NULL, /* base_finalize */
101 NULL, /* class_finalize */
102 NULL, /* class_data */
108 _type = g_type_register_static (G_TYPE_INTERFACE, "GstTagSetter",
109 &tag_setter_info, 0);
111 g_type_interface_add_prerequisite (_type, GST_TYPE_ELEMENT);
113 gst_tag_key = g_quark_from_static_string ("GST_TAG_SETTER");
114 g_once_init_leave (&tag_setter_type, _type);
117 return tag_setter_type;
121 gst_tag_data_free (gpointer p)
123 GstTagData *data = (GstTagData *) p;
126 gst_tag_list_free (data->list);
128 g_static_mutex_free (&data->lock);
130 g_slice_free (GstTagData, data);
134 gst_tag_setter_get_data (GstTagSetter * setter)
138 data = g_object_get_qdata (G_OBJECT (setter), gst_tag_key);
140 static GStaticMutex create_mutex = G_STATIC_MUTEX_INIT;
142 /* make sure no other thread is creating a GstTagData at the same time */
143 g_static_mutex_lock (&create_mutex);
144 data = g_object_get_qdata (G_OBJECT (setter), gst_tag_key);
146 data = g_slice_new (GstTagData);
147 g_static_mutex_init (&data->lock);
149 data->mode = GST_TAG_MERGE_KEEP;
150 g_object_set_qdata_full (G_OBJECT (setter), gst_tag_key, data,
153 g_static_mutex_unlock (&create_mutex);
160 * gst_tag_setter_reset_tags:
161 * @setter: a #GstTagSetter
163 * Reset the internal taglist. Elements should call this from within the
164 * state-change handler.
169 gst_tag_setter_reset_tags (GstTagSetter * setter)
173 g_return_if_fail (GST_IS_TAG_SETTER (setter));
175 data = gst_tag_setter_get_data (setter);
177 g_static_mutex_lock (&data->lock);
179 gst_tag_list_free (data->list);
182 g_static_mutex_unlock (&data->lock);
186 * gst_tag_setter_merge_tags:
187 * @setter: a #GstTagSetter
188 * @list: a tag list to merge from
189 * @mode: the mode to merge with
191 * Merges the given list into the setter's list using the given mode.
194 gst_tag_setter_merge_tags (GstTagSetter * setter, const GstTagList * list,
195 GstTagMergeMode mode)
199 g_return_if_fail (GST_IS_TAG_SETTER (setter));
200 g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
201 g_return_if_fail (GST_IS_TAG_LIST (list));
203 data = gst_tag_setter_get_data (setter);
205 g_static_mutex_lock (&data->lock);
206 if (data->list == NULL) {
207 if (mode != GST_TAG_MERGE_KEEP_ALL)
208 data->list = gst_tag_list_copy (list);
210 gst_tag_list_insert (data->list, list, mode);
212 g_static_mutex_unlock (&data->lock);
216 * gst_tag_setter_add_tags:
217 * @setter: a #GstTagSetter
218 * @mode: the mode to use
220 * @...: more tag / value pairs to set
222 * Adds the given tag / value pairs on the setter using the given merge mode.
223 * The list must be terminated with NULL.
226 gst_tag_setter_add_tags (GstTagSetter * setter, GstTagMergeMode mode,
227 const gchar * tag, ...)
231 g_return_if_fail (GST_IS_TAG_SETTER (setter));
232 g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
234 va_start (args, tag);
235 gst_tag_setter_add_tag_valist (setter, mode, tag, args);
240 * gst_tag_setter_add_tag_values:
241 * @setter: a #GstTagSetter
242 * @mode: the mode to use
244 * @...: more tag / GValue pairs to set
246 * Adds the given tag / GValue pairs on the setter using the given merge mode.
247 * The list must be terminated with NULL.
250 gst_tag_setter_add_tag_values (GstTagSetter * setter, GstTagMergeMode mode,
251 const gchar * tag, ...)
255 g_return_if_fail (GST_IS_TAG_SETTER (setter));
256 g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
258 va_start (args, tag);
259 gst_tag_setter_add_tag_valist_values (setter, mode, tag, args);
264 * gst_tag_setter_add_tag_valist:
265 * @setter: a #GstTagSetter
266 * @mode: the mode to use
268 * @var_args: tag / value pairs to set
270 * Adds the given tag / value pairs on the setter using the given merge mode.
271 * The list must be terminated with NULL.
274 gst_tag_setter_add_tag_valist (GstTagSetter * setter, GstTagMergeMode mode,
275 const gchar * tag, va_list var_args)
279 g_return_if_fail (GST_IS_TAG_SETTER (setter));
280 g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
282 data = gst_tag_setter_get_data (setter);
284 g_static_mutex_lock (&data->lock);
286 data->list = gst_tag_list_new ();
288 gst_tag_list_add_valist (data->list, mode, tag, var_args);
290 g_static_mutex_unlock (&data->lock);
294 * gst_tag_setter_add_tag_valist_values:
295 * @setter: a #GstTagSetter
296 * @mode: the mode to use
298 * @var_args: tag / GValue pairs to set
300 * Adds the given tag / GValue pairs on the setter using the given merge mode.
301 * The list must be terminated with NULL.
304 gst_tag_setter_add_tag_valist_values (GstTagSetter * setter,
305 GstTagMergeMode mode, const gchar * tag, va_list var_args)
309 g_return_if_fail (GST_IS_TAG_SETTER (setter));
310 g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
312 data = gst_tag_setter_get_data (setter);
314 g_static_mutex_lock (&data->lock);
317 data->list = gst_tag_list_new ();
319 gst_tag_list_add_valist_values (data->list, mode, tag, var_args);
321 g_static_mutex_unlock (&data->lock);
325 * gst_tag_setter_add_tag_value:
326 * @setter: a #GstTagSetter
327 * @mode: the mode to use
329 * @value: GValue to set for the tag
331 * Adds the given tag / GValue pair on the setter using the given merge mode.
336 gst_tag_setter_add_tag_value (GstTagSetter * setter,
337 GstTagMergeMode mode, const gchar * tag, const GValue * value)
341 g_return_if_fail (GST_IS_TAG_SETTER (setter));
342 g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
344 data = gst_tag_setter_get_data (setter);
346 g_static_mutex_lock (&data->lock);
349 data->list = gst_tag_list_new ();
351 gst_tag_list_add_value (data->list, mode, tag, value);
353 g_static_mutex_unlock (&data->lock);
357 * gst_tag_setter_get_tag_list:
358 * @setter: a #GstTagSetter
360 * Returns the current list of tags the setter uses. The list should not be
363 * This function is not thread-safe.
365 * Returns: (transfer none): a current snapshot of the taglist used in the
366 * setter or NULL if none is used.
368 G_CONST_RETURN GstTagList *
369 gst_tag_setter_get_tag_list (GstTagSetter * setter)
371 g_return_val_if_fail (GST_IS_TAG_SETTER (setter), NULL);
373 return gst_tag_setter_get_data (setter)->list;
377 * gst_tag_setter_set_tag_merge_mode:
378 * @setter: a #GstTagSetter
379 * @mode: The mode with which tags are added
381 * Sets the given merge mode that is used for adding tags from events to tags
382 * specified by this interface. The default is #GST_TAG_MERGE_KEEP, which keeps
383 * the tags set with this interface and discards tags from events.
386 gst_tag_setter_set_tag_merge_mode (GstTagSetter * setter, GstTagMergeMode mode)
390 g_return_if_fail (GST_IS_TAG_SETTER (setter));
391 g_return_if_fail (GST_TAG_MODE_IS_VALID (mode));
393 data = gst_tag_setter_get_data (setter);
395 g_static_mutex_lock (&data->lock);
397 g_static_mutex_unlock (&data->lock);
401 * gst_tag_setter_get_tag_merge_mode:
402 * @setter: a #GstTagSetter
404 * Queries the mode by which tags inside the setter are overwritten by tags
407 * Returns: the merge mode used inside the element.
410 gst_tag_setter_get_tag_merge_mode (GstTagSetter * setter)
412 GstTagMergeMode mode;
415 g_return_val_if_fail (GST_IS_TAG_SETTER (setter), GST_TAG_MERGE_UNDEFINED);
417 data = gst_tag_setter_get_data (setter);
419 g_static_mutex_lock (&data->lock);
421 g_static_mutex_unlock (&data->lock);