gstreamer/gst-libs/gst/audio/mixerutils.c
2011-05-24 18:21:06 +02:00

246 lines
7.6 KiB
C

/* 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_OBJECT_NAME (GST_PLUGIN_FEATURE (a));
const gchar *name_b = GST_OBJECT_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);
}