2 * Copyright (C) 2003-2004 Ronald Bultje <rbultje@ronald.bitfreak.net>
3 * Copyright (C) 2005-2006 Tim-Philipp Müller <tim centricular net>
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Library General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Library General Public License for more details.
15 * You should have received a copy of the GNU Library General Public
16 * License along with this library; if not, write to the
17 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 * Boston, MA 02111-1307, USA.
22 * SECTION:gstaudiomixerutils
23 * @short_description: utility functions to find available audio mixers
24 * from the plugin registry
28 * Provides some utility functions to detect available audio mixers
38 #include "mixerutils.h"
40 #include <gst/interfaces/propertyprobe.h>
45 gst_audio_mixer_filter_do_filter (GstAudioMixerFilterFunc filter_func,
46 GstElementFactory * factory,
47 GstElement ** p_element, GList ** p_collection, gpointer user_data)
49 /* so, the element is a mixer, let's see if the caller wants it */
50 if (filter_func != NULL) {
51 if (filter_func (GST_MIXER (*p_element), user_data) == TRUE) {
52 *p_collection = g_list_prepend (*p_collection, *p_element);
53 /* do not set state back to NULL here on purpose, caller
54 * might want to keep the mixer open */
58 gst_element_set_state (*p_element, GST_STATE_NULL);
59 *p_collection = g_list_prepend (*p_collection, *p_element);
63 /* create new element for further probing if the old one was cleared */
64 if (*p_element == NULL) {
65 *p_element = gst_element_factory_create (factory, NULL);
70 gst_audio_mixer_filter_check_element (GstElement * element)
72 GstStateChangeReturn ret;
74 /* open device (only then we can know for sure whether it is a mixer) */
75 gst_element_set_state (element, GST_STATE_READY);
76 ret = gst_element_get_state (element, NULL, NULL, 1 * GST_SECOND);
77 if (ret != GST_STATE_CHANGE_SUCCESS) {
78 GST_DEBUG ("could not open device / set element to READY");
79 gst_element_set_state (element, GST_STATE_NULL);
83 /* is this device a mixer? */
84 if (!GST_IS_MIXER (element)) {
85 GST_DEBUG ("element is not a mixer");
86 gst_element_set_state (element, GST_STATE_NULL);
91 if (!gst_mixer_list_tracks (GST_MIXER (element))) {
92 GST_DEBUG ("element is a mixer, but has no tracks");
93 gst_element_set_state (element, GST_STATE_NULL);
97 GST_DEBUG ("element is a mixer with mixer tracks");
102 gst_audio_mixer_filter_probe_feature (GstAudioMixerFilterFunc filter_func,
103 GstElementFactory * factory,
104 GList ** p_collection, gboolean first, gpointer user_data)
108 GST_DEBUG ("probing %s ...", gst_element_factory_get_longname (factory));
111 element = gst_element_factory_create (factory, NULL);
113 if (element == NULL) {
114 GST_DEBUG ("could not create element from factory");
118 GST_DEBUG ("created element %s (%p)", GST_ELEMENT_NAME (element), element);
120 if (GST_IS_PROPERTY_PROBE (element)) {
121 GstPropertyProbe *probe;
122 const GParamSpec *devspec;
124 probe = GST_PROPERTY_PROBE (element);
126 GST_DEBUG ("probing available devices ...");
127 if ((devspec = gst_property_probe_get_property (probe, "device"))) {
130 if ((array = gst_property_probe_probe_and_get_values (probe, devspec))) {
133 GST_DEBUG ("there are %d available devices", array->n_values);
135 /* set all devices and test for mixer */
136 for (n = 0; n < array->n_values; n++) {
139 /* set this device */
140 device = g_value_array_get_nth (array, n);
141 g_object_set_property (G_OBJECT (element), "device", device);
143 GST_DEBUG ("trying device %s ..", g_value_get_string (device));
145 if (gst_audio_mixer_filter_check_element (element)) {
146 gst_audio_mixer_filter_do_filter (filter_func, factory, &element,
147 p_collection, user_data);
149 if (first && *p_collection != NULL) {
150 GST_DEBUG ("Stopping after first found mixer, as requested");
155 g_value_array_free (array);
159 GST_DEBUG ("element does not support the property probe interface");
161 if (gst_audio_mixer_filter_check_element (element)) {
162 gst_audio_mixer_filter_do_filter (filter_func, factory, &element,
163 p_collection, user_data);
168 gst_element_set_state (element, GST_STATE_NULL);
169 gst_object_unref (element);
174 element_factory_rank_compare_func (gconstpointer a, gconstpointer b)
176 gint rank_a = gst_plugin_feature_get_rank (GST_PLUGIN_FEATURE (a));
177 gint rank_b = gst_plugin_feature_get_rank (GST_PLUGIN_FEATURE (b));
179 /* make order chosen in the end more determinable */
180 if (rank_a == rank_b) {
181 const gchar *name_a = GST_PLUGIN_FEATURE_NAME (GST_PLUGIN_FEATURE (a));
182 const gchar *name_b = GST_PLUGIN_FEATURE_NAME (GST_PLUGIN_FEATURE (b));
184 return g_ascii_strcasecmp (name_a, name_b);
187 return rank_b - rank_a;
191 * gst_audio_default_registry_mixer_filter:
192 * @filter_func: filter function, or #NULL
193 * @first: set to #TRUE if you only want the first suitable mixer element
194 * @user_data: user data to pass to the filter function
196 * Utility function to find audio mixer elements.
198 * Will traverse the default plugin registry in order of plugin rank and
199 * find usable audio mixer elements. The caller may optionally fine-tune
200 * the selection by specifying a filter function.
202 * Returns: a #GList of audio mixer #GstElement<!-- -->s. You must free each
203 * element in the list by setting it to NULL state and calling
204 * gst_object_unref(). After that the list itself should be freed
205 * using g_list_free().
210 gst_audio_default_registry_mixer_filter (GstAudioMixerFilterFunc filter_func,
211 gboolean first, gpointer data)
213 GList *mixer_list = NULL;
217 /* go through all elements of a certain class and check whether
218 * they implement a mixer. If so, add it to the list. */
219 feature_list = gst_registry_get_feature_list (gst_registry_get_default (),
220 GST_TYPE_ELEMENT_FACTORY);
222 feature_list = g_list_sort (feature_list, element_factory_rank_compare_func);
224 for (walk = feature_list; walk != NULL; walk = walk->next) {
225 GstElementFactory *factory;
228 factory = GST_ELEMENT_FACTORY (walk->data);
231 klass = gst_element_factory_get_klass (factory);
232 if (strcmp (klass, "Generic/Audio") == 0) {
233 gst_audio_mixer_filter_probe_feature (filter_func, factory,
234 &mixer_list, first, data);
237 if (first && mixer_list != NULL) {
238 GST_DEBUG ("Stopping after first found mixer, as requested");
243 gst_plugin_feature_list_free (feature_list);
245 return g_list_reverse (mixer_list);