gst-libs/gst/audio/: Add gst_audio_default_registry_mixer_filter() utility function.

Original commit message from CVS:
* gst-libs/gst/audio/Makefile.am:
* gst-libs/gst/audio/mixerutils.c:
(gst_audio_mixer_filter_do_filter),
(gst_audio_mixer_filter_check_element),
(gst_audio_mixer_filter_probe_feature),
(element_factory_rank_compare_func),
(gst_audio_default_registry_mixer_filter):
* gst-libs/gst/audio/mixerutils.h:
Add gst_audio_default_registry_mixer_filter() utility
function.

ChangeLog

@@ -1,3 +1,16 @@
+2006-01-09  Tim-Philipp Müller  <tim at centricular dot net>
+
+	* gst-libs/gst/audio/Makefile.am:
+	* gst-libs/gst/audio/mixerutils.c:
+	(gst_audio_mixer_filter_do_filter),
+	(gst_audio_mixer_filter_check_element),
+	(gst_audio_mixer_filter_probe_feature),
+	(element_factory_rank_compare_func),
+	(gst_audio_default_registry_mixer_filter):
+	* gst-libs/gst/audio/mixerutils.h:
+	  Add gst_audio_default_registry_mixer_filter() utility
+	  function.
+
 2006-01-03  Michael Smith  <msmith@fluendo.com>
 
 	* gst/audioresample/resample.h:

common

@@ -1 +1 @@
-Subproject commit d1911d4b3d6267f9cd9dfb68fcef2afe4d098092
+Subproject commit e0b121388ece524c0b7035a72bddd191d122d8bf

gst-libs/gst/audio/Makefile.am

@@ -15,7 +15,10 @@ EXTRA_DIST = gstaudiofiltertemplate.c make_filter
 CLEANFILES = gstaudiofilterexample.c \
 	$(BUILT_SOURCES)
 
-libgstaudio_@GST_MAJORMINOR@_la_SOURCES = audio.c gstaudioclock.c \
+libgstaudio_@GST_MAJORMINOR@_la_SOURCES = \
+	audio.c \
+	gstaudioclock.c \
+	mixerutils.c \
 	multichannel.c \
 	gstaudiofilter.c \
 	gstaudiosink.c \
@@ -35,6 +38,7 @@ libgstaudio_@GST_MAJORMINOR@include_HEADERS = \
 	gstbaseaudiosink.h \
 	gstbaseaudiosrc.h \
 	gstringbuffer.h \
+	mixerutils.h \
 	multichannel.h
 
 nodist_libgstaudio_@GST_MAJORMINOR@include_HEADERS = \

gst-libs/gst/audio/mixerutils.c

@@ -0,0 +1,206 @@
+/* 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.
+ */
+
+#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 */
+  if (*p_element == NULL) {
+    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));
+
+  return rank_b - rank_a;
+}
+
+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);
+}

gst-libs/gst/audio/mixerutils.h

@@ -0,0 +1,32 @@
+/* GStreamer
+ * 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.
+ */
+
+#ifndef __GST_AUDIO_MIXERUTILS_H__
+#define __GST_AUDIO_MIXERUTILS_H__
+
+#include <gst/gst.h>
+#include <gst/interfaces/mixer.h>
+
+typedef gboolean (*GstAudioMixerFilterFunc) (GstMixer * mixer, gpointer user_data);
+
+GList * gst_audio_default_registry_mixer_filter (GstAudioMixerFilterFunc  filter_func,
+                                                 gboolean                 first,
+                                                 gpointer                 user_data);
+
+#endif /* __GST_AUDIO_MIXERUTILS_H__ */