--- /dev/null
+/* GStreamer
+ * Copyright (C) 2003-2004 Ronald Bultje <rbultje@ronald.bitfreak.net>
+ * Copyright (C) 2005-2006 Tim-Philipp Müller <tim centricular net>
+ *
+ * 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+/**
+ * SECTION:gstaudiomixerutils
+ * @short_description: utility functions to find available audio mixers
+ * from the plugin registry
+ *
+ * <refsect2>
+ * <para>
+ * Provides some utility functions to detect available audio mixers
+ * on the system.
+ * </para>
+ * </refsect2>
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "mixerutils.h"
+
+#include <gst/interfaces/propertyprobe.h>
+
+#include <string.h>
+
+static void
+gst_audio_mixer_filter_do_filter (GstAudioMixerFilterFunc filter_func,
+ GstElementFactory * factory,
+ GstElement ** p_element, GList ** p_collection, gpointer user_data)
+{
+ /* so, the element is a mixer, let's see if the caller wants it */
+ if (filter_func != NULL) {
+ if (filter_func (GST_MIXER (*p_element), user_data) == TRUE) {
+ *p_collection = g_list_prepend (*p_collection, *p_element);
+ /* do not set state back to NULL here on purpose, caller
+ * might want to keep the mixer open */
+ *p_element = NULL;
+ }
+ } else {
+ gst_element_set_state (*p_element, GST_STATE_NULL);
+ *p_collection = g_list_prepend (*p_collection, *p_element);
+ *p_element = NULL;
+ }
+
+ /* create new element for further probing if the old one was cleared */
+ if (*p_element == NULL) {
+ *p_element = gst_element_factory_create (factory, NULL);
+ }
+}
+
+static gboolean
+gst_audio_mixer_filter_check_element (GstElement * element)
+{
+ GstStateChangeReturn ret;
+
+ /* open device (only then we can know for sure whether it is a mixer) */
+ gst_element_set_state (element, GST_STATE_READY);
+ ret = gst_element_get_state (element, NULL, NULL, 1 * GST_SECOND);
+ if (ret != GST_STATE_CHANGE_SUCCESS) {
+ GST_DEBUG ("could not open device / set element to READY");
+ gst_element_set_state (element, GST_STATE_NULL);
+ return FALSE;
+ }
+
+ /* is this device a mixer? */
+ if (!GST_IS_MIXER (element)) {
+ GST_DEBUG ("element is not a mixer");
+ gst_element_set_state (element, GST_STATE_NULL);
+ return FALSE;
+ }
+
+ /* any tracks? */
+ if (!gst_mixer_list_tracks (GST_MIXER (element))) {
+ GST_DEBUG ("element is a mixer, but has no tracks");
+ gst_element_set_state (element, GST_STATE_NULL);
+ return FALSE;
+ }
+
+ GST_DEBUG ("element is a mixer with mixer tracks");
+ return TRUE;
+}
+
+static void
+gst_audio_mixer_filter_probe_feature (GstAudioMixerFilterFunc filter_func,
+ GstElementFactory * factory,
+ GList ** p_collection, gboolean first, gpointer user_data)
+{
+ GstElement *element;
+
+ GST_DEBUG ("probing %s ...", gst_element_factory_get_longname (factory));
+
+ /* create element */
+ element = gst_element_factory_create (factory, NULL);
+
+ if (element == NULL) {
+ GST_DEBUG ("could not create element from factory");
+ return;
+ }
+
+ GST_DEBUG ("created element %s (%p)", GST_ELEMENT_NAME (element), element);
+
+ if (GST_IS_PROPERTY_PROBE (element)) {
+ GstPropertyProbe *probe;
+ const GParamSpec *devspec;
+
+ probe = GST_PROPERTY_PROBE (element);
+
+ GST_DEBUG ("probing available devices ...");
+ if ((devspec = gst_property_probe_get_property (probe, "device"))) {
+ GValueArray *array;
+
+ if ((array = gst_property_probe_probe_and_get_values (probe, devspec))) {
+ guint n;
+
+ GST_DEBUG ("there are %d available devices", array->n_values);
+
+ /* set all devices and test for mixer */
+ for (n = 0; n < array->n_values; n++) {
+ GValue *device;
+
+ /* set this device */
+ device = g_value_array_get_nth (array, n);
+ g_object_set_property (G_OBJECT (element), "device", device);
+
+ GST_DEBUG ("trying device %s ..", g_value_get_string (device));
+
+ if (gst_audio_mixer_filter_check_element (element)) {
+ gst_audio_mixer_filter_do_filter (filter_func, factory, &element,
+ p_collection, user_data);
+
+ if (first && *p_collection != NULL) {
+ GST_DEBUG ("Stopping after first found mixer, as requested");
+ break;
+ }
+ }
+ }
+ g_value_array_free (array);
+ }
+ }
+ } else {
+ GST_DEBUG ("element does not support the property probe interface");
+
+ if (gst_audio_mixer_filter_check_element (element)) {
+ gst_audio_mixer_filter_do_filter (filter_func, factory, &element,
+ p_collection, user_data);
+ }
+ }
+
+ if (element) {
+ gst_element_set_state (element, GST_STATE_NULL);
+ gst_object_unref (element);
+ }
+}
+
+static gint
+element_factory_rank_compare_func (gconstpointer a, gconstpointer b)
+{
+ gint rank_a = gst_plugin_feature_get_rank (GST_PLUGIN_FEATURE (a));
+ gint rank_b = gst_plugin_feature_get_rank (GST_PLUGIN_FEATURE (b));
+
+ /* make order chosen in the end more determinable */
+ if (rank_a == rank_b) {
+ const gchar *name_a = GST_PLUGIN_FEATURE_NAME (GST_PLUGIN_FEATURE (a));
+ const gchar *name_b = GST_PLUGIN_FEATURE_NAME (GST_PLUGIN_FEATURE (b));
+
+ return g_ascii_strcasecmp (name_a, name_b);
+ }
+
+ return rank_b - rank_a;
+}
+
+/**
+ * gst_audio_default_registry_mixer_filter:
+ * @filter_func: filter function, or #NULL
+ * @first: set to #TRUE if you only want the first suitable mixer element
+ * @user_data: user data to pass to the filter function
+ *
+ * Utility function to find audio mixer elements.
+ *
+ * Will traverse the default plugin registry in order of plugin rank and
+ * find usable audio mixer elements. The caller may optionally fine-tune
+ * the selection by specifying a filter function.
+ *
+ * Returns: a #GList of audio mixer #GstElement<!-- -->s. You must free each
+ * element in the list by setting it to NULL state and calling
+ * gst_object_unref(). After that the list itself should be freed
+ * using g_list_free().
+ *
+ * Since: 0.10.2
+ */
+GList *
+gst_audio_default_registry_mixer_filter (GstAudioMixerFilterFunc filter_func,
+ gboolean first, gpointer data)
+{
+ GList *mixer_list = NULL;
+ GList *feature_list;
+ GList *walk;
+
+ /* go through all elements of a certain class and check whether
+ * they implement a mixer. If so, add it to the list. */
+ feature_list = gst_registry_get_feature_list (gst_registry_get_default (),
+ GST_TYPE_ELEMENT_FACTORY);
+
+ feature_list = g_list_sort (feature_list, element_factory_rank_compare_func);
+
+ for (walk = feature_list; walk != NULL; walk = walk->next) {
+ GstElementFactory *factory;
+ const gchar *klass;
+
+ factory = GST_ELEMENT_FACTORY (walk->data);
+
+ /* check category */
+ klass = gst_element_factory_get_klass (factory);
+ if (strcmp (klass, "Generic/Audio") == 0) {
+ gst_audio_mixer_filter_probe_feature (filter_func, factory,
+ &mixer_list, first, data);
+ }
+
+ if (first && mixer_list != NULL) {
+ GST_DEBUG ("Stopping after first found mixer, as requested");
+ break;
+ }
+ }
+
+ gst_plugin_feature_list_free (feature_list);
+
+ return g_list_reverse (mixer_list);
+}
projects / mafwsubrenderer / blobdiff