libpurple/mediamanager.c

/* purple
 *
 * Purple is the legal property of its developers, whose names are too numerous
 * to list here.  Please refer to the COPYRIGHT file distributed with this
 * source distribution.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02111-1301  USA
 */

#include <glib/gi18n-lib.h>

#include "debug.h"
#include "glibcompat.h"
#include "media.h"
#include "mediamanager.h"
#include "purpleaccount.h"
#include "purplepath.h"

#include "media-gst.h"

#include <gst/app/app.h>

typedef struct _PurpleMediaOutputWindow PurpleMediaOutputWindow;
typedef struct _PurpleMediaElementInfoPrivate PurpleMediaElementInfoPrivate;

struct _PurpleMediaOutputWindow
{
	gulong id;
	PurpleMedia *media;
	gchar *session_id;
	gchar *participant;
	GstElement *sink;
};

typedef struct
{
	GstElement *pipeline;
	PurpleMediaCaps ui_caps;
	GList *medias;
	GList *private_medias;
	GList *elements;
	GList *output_windows;
	gulong next_output_window_id;
	GType backend_type;
	GstCaps *video_caps;

	PurpleMediaElementInfo *video_src;
	PurpleMediaElementInfo *video_sink;
	PurpleMediaElementInfo *audio_src;
	PurpleMediaElementInfo *audio_sink;

	GstDeviceMonitor *device_monitor;

	/* Application data streams */
	GList *appdata_info; /* holds PurpleMediaAppDataInfo */
	GMutex appdata_mutex;
	guint appdata_cb_token; /* last used read/write callback token */
} PurpleMediaManagerPrivate;

/**
 * PurpleMediaManager:
 *
 * The media manager's data.
 */
struct _PurpleMediaManager
{
	GObject parent;

	/*< private >*/
	PurpleMediaManagerPrivate *priv;
};

typedef struct {
	PurpleMedia *media;
	GWeakRef media_ref;
	gchar *session_id;
	gchar *participant;
	PurpleMediaAppDataCallbacks callbacks;
	gpointer user_data;
	GDestroyNotify notify;
	GstAppSrc *appsrc;
	GstAppSink *appsink;
	gint num_samples;
	GstSample *current_sample;
	guint sample_offset;
	gboolean writable;
	gboolean connected;
	guint writable_cb_token;
	guint readable_cb_token;
	guint writable_timer_id;
	guint readable_timer_id;
	GCond readable_cond;
} PurpleMediaAppDataInfo;

static void purple_media_manager_finalize (GObject *object);
static void free_appdata_info_locked (PurpleMediaAppDataInfo *info);
static void purple_media_manager_init_device_monitor(PurpleMediaManager *manager);
static void purple_media_manager_register_static_elements(PurpleMediaManager *manager);


enum {
	INIT_MEDIA,
	INIT_PRIVATE_MEDIA,
	UI_CAPS_CHANGED,
	ELEMENTS_CHANGED,
	LAST_SIGNAL
};
static guint purple_media_manager_signals[LAST_SIGNAL] = {0};

G_DEFINE_TYPE_WITH_PRIVATE(PurpleMediaManager, purple_media_manager,
		G_TYPE_OBJECT);

static void
purple_media_manager_class_init (PurpleMediaManagerClass *klass)
{
	GObjectClass *gobject_class = (GObjectClass*)klass;

	gobject_class->finalize = purple_media_manager_finalize;

	purple_media_manager_signals[INIT_MEDIA] = g_signal_new ("init-media",
		G_TYPE_FROM_CLASS (klass),
		G_SIGNAL_RUN_LAST,
		0, NULL, NULL, NULL,
		G_TYPE_BOOLEAN, 3, PURPLE_TYPE_MEDIA,
		G_TYPE_POINTER, G_TYPE_STRING);

	purple_media_manager_signals[INIT_PRIVATE_MEDIA] =
		g_signal_new ("init-private-media",
			G_TYPE_FROM_CLASS (klass),
			G_SIGNAL_RUN_LAST,
			0, NULL, NULL, NULL,
			G_TYPE_BOOLEAN, 3, PURPLE_TYPE_MEDIA,
			G_TYPE_POINTER, G_TYPE_STRING);

	purple_media_manager_signals[UI_CAPS_CHANGED] = g_signal_new ("ui-caps-changed",
		G_TYPE_FROM_CLASS (klass),
		G_SIGNAL_RUN_LAST,
		0, NULL, NULL, NULL,
		G_TYPE_NONE, 2, PURPLE_MEDIA_TYPE_CAPS,
		PURPLE_MEDIA_TYPE_CAPS);

	purple_media_manager_signals[ELEMENTS_CHANGED] =
		g_signal_new("elements-changed",
			G_TYPE_FROM_CLASS(klass),
			G_SIGNAL_RUN_LAST | G_SIGNAL_DETAILED,
			0, NULL, NULL, NULL,
			G_TYPE_NONE, 0);
}

static void
purple_media_manager_init (PurpleMediaManager *media)
{
	GError *error = NULL;

	media->priv = purple_media_manager_get_instance_private(media);
	media->priv->medias = NULL;
	media->priv->private_medias = NULL;
	media->priv->next_output_window_id = 1;
	media->priv->appdata_info = NULL;
	g_mutex_init (&media->priv->appdata_mutex);
	if (gst_init_check(NULL, NULL, &error)) {
		purple_media_manager_register_static_elements(media);
		purple_media_manager_init_device_monitor(media);
	} else {
		purple_debug_error("mediamanager",
				"GStreamer failed to initialize: %s.",
				error ? error->message : "");
		g_clear_error(&error);
	}

	purple_prefs_add_none("/purple/media");
	purple_prefs_add_none("/purple/media/audio");
	purple_prefs_add_int("/purple/media/audio/silence_threshold", 5);
	purple_prefs_add_none("/purple/media/audio/volume");
	purple_prefs_add_int("/purple/media/audio/volume/input", 10);
	purple_prefs_add_int("/purple/media/audio/volume/output", 10);
}

static void
purple_media_manager_finalize (GObject *media)
{
	PurpleMediaManagerPrivate *priv =
			purple_media_manager_get_instance_private(
					PURPLE_MEDIA_MANAGER(media));

	g_list_free_full(priv->medias, g_object_unref);
	g_list_free_full(priv->private_medias, g_object_unref);
	g_list_free_full(priv->elements, g_object_unref);
	g_clear_pointer(&priv->video_caps, gst_caps_unref);
	g_clear_list(&priv->appdata_info,
	             (GDestroyNotify)free_appdata_info_locked);
	g_mutex_clear (&priv->appdata_mutex);
	if (priv->device_monitor) {
		gst_device_monitor_stop(priv->device_monitor);
		g_object_unref(priv->device_monitor);
	}

	G_OBJECT_CLASS(purple_media_manager_parent_class)->finalize(media);
}

PurpleMediaManager *
purple_media_manager_get(void)
{
	static PurpleMediaManager *manager = NULL;

	if (manager == NULL) {
		manager = PURPLE_MEDIA_MANAGER(g_object_new(purple_media_manager_get_type(), NULL));
	}

	return manager;
}

static gboolean
pipeline_bus_call(G_GNUC_UNUSED GstBus *bus, GstMessage *msg,
                  G_GNUC_UNUSED PurpleMediaManager *manager)
{
	switch(GST_MESSAGE_TYPE(msg)) {
		case GST_MESSAGE_EOS:
			purple_debug_info("mediamanager", "End of Stream");
			break;
		case GST_MESSAGE_ERROR: {
			gchar *debug = NULL;
			GError *err = NULL;

			gst_message_parse_error(msg, &err, &debug);

			purple_debug_error("mediamanager", "gst pipeline error: %s",
			                   err->message);
			g_error_free(err);

			if (debug) {
				purple_debug_error("mediamanager", "Debug details: %s", debug);
				g_free(debug);
			}
			break;
		}
		default:
			break;
	}
	return TRUE;
}

GstElement *
purple_media_manager_get_pipeline(PurpleMediaManager *manager)
{
	g_return_val_if_fail(PURPLE_IS_MEDIA_MANAGER(manager), NULL);

	if (manager->priv->pipeline == NULL) {
		GstBus *bus;
		manager->priv->pipeline = gst_pipeline_new(NULL);

		bus = gst_pipeline_get_bus(
				GST_PIPELINE(manager->priv->pipeline));
		gst_bus_add_signal_watch(GST_BUS(bus));
		g_signal_connect(G_OBJECT(bus), "message",
				G_CALLBACK(pipeline_bus_call), manager);
		gst_bus_set_sync_handler(bus, gst_bus_sync_signal_handler, NULL, NULL);
		gst_object_unref(bus);

		gst_element_set_state(manager->priv->pipeline,
				GST_STATE_PLAYING);
	}

	return manager->priv->pipeline;
}

static PurpleMedia *
create_media(PurpleMediaManager *manager,
			  PurpleAccount *account,
			  const char *conference_type,
			  const char *remote_user,
			  gboolean initiator,
			  gboolean private)
{
	PurpleMedia *media;
	guint signal_id;

	media = PURPLE_MEDIA(g_object_new(purple_media_get_type(),
			     "manager", manager,
			     "account", account,
			     "conference-type", conference_type,
			     "initiator", initiator,
			     NULL));

	signal_id = private ?
			purple_media_manager_signals[INIT_PRIVATE_MEDIA] :
			purple_media_manager_signals[INIT_MEDIA];

	if (g_signal_has_handler_pending(manager, signal_id, 0, FALSE)) {
		gboolean signal_ret;

		g_signal_emit(manager, signal_id, 0, media, account, remote_user,
				&signal_ret);
		if (signal_ret == FALSE) {
			g_object_unref(media);
			return NULL;
		}
	}

	if (private) {
		manager->priv->private_medias = g_list_append(
			manager->priv->private_medias, media);
	} else {
		manager->priv->medias = g_list_append(manager->priv->medias, media);
	}

	return media;
}

static GList *
get_media(PurpleMediaManager *manager, gboolean private)
{
	if (private) {
		return manager->priv->private_medias;
	} else {
		return manager->priv->medias;
	}
}

static GList *
get_media_by_account(PurpleMediaManager *manager,
		PurpleAccount *account, gboolean private)
{
	GList *media = NULL;
	GList *iter;
	PurpleAccount *media_account;

	g_return_val_if_fail(PURPLE_IS_MEDIA_MANAGER(manager), NULL);

	if (private) {
		iter = manager->priv->private_medias;
	} else {
		iter = manager->priv->medias;
	}
	for (; iter; iter = g_list_next(iter)) {
		media_account = purple_media_get_account(iter->data);
		if (media_account == account) {
			media = g_list_prepend(media, iter->data);
		}
		g_object_unref (media_account);
	}

	return media;
}

void
purple_media_manager_remove_media(PurpleMediaManager *manager, PurpleMedia *media)
{
	GList *list;
	GList **medias = NULL;

	g_return_if_fail(manager != NULL);

	if ((list = g_list_find(manager->priv->medias, media))) {
		medias = &manager->priv->medias;
	} else if ((list = g_list_find(manager->priv->private_medias, media))) {
		medias = &manager->priv->private_medias;
	}

	if (list) {
		*medias = g_list_delete_link(*medias, list);

		g_mutex_lock (&manager->priv->appdata_mutex);
		list = manager->priv->appdata_info;
		while (list) {
			PurpleMediaAppDataInfo *info = list->data;
			GList *next = list->next;

			if (info->media == media) {
				manager->priv->appdata_info = g_list_delete_link (
					manager->priv->appdata_info, list);
				free_appdata_info_locked (info);
			}

			list = next;
		}
		g_mutex_unlock (&manager->priv->appdata_mutex);
	}
}

PurpleMedia *
purple_media_manager_create_media(PurpleMediaManager *manager,
				  PurpleAccount *account,
				  const char *conference_type,
				  const char *remote_user,
				  gboolean initiator)
{
	return create_media (manager, account, conference_type,
						  remote_user, initiator, FALSE);
}

GList *
purple_media_manager_get_media(PurpleMediaManager *manager)
{
	return get_media (manager, FALSE);
}

GList *
purple_media_manager_get_media_by_account(PurpleMediaManager *manager,
		PurpleAccount *account)
{
	return get_media_by_account (manager, account, FALSE);
}

PurpleMedia *
purple_media_manager_create_private_media(PurpleMediaManager *manager,
				  PurpleAccount *account,
				  const char *conference_type,
				  const char *remote_user,
				  gboolean initiator)
{
	return create_media (manager, account, conference_type,
		remote_user, initiator, TRUE);
}

GList *
purple_media_manager_get_private_media(PurpleMediaManager *manager)
{
	return get_media (manager, TRUE);
}

GList *
purple_media_manager_get_private_media_by_account(PurpleMediaManager *manager,
		PurpleAccount *account)
{
	return get_media_by_account (manager, account, TRUE);
}

static void
free_appdata_info_locked (PurpleMediaAppDataInfo *info)
{
	GstAppSrcCallbacks null_src_cb = {
		.need_data = NULL,
		.enough_data = NULL,
		.seek_data = NULL,
	};
	GstAppSinkCallbacks null_sink_cb = {
		.eos = NULL,
		.new_preroll = NULL,
		.new_sample = NULL,
	};

	if (info->notify) {
		info->notify(info->user_data);
	}

	info->media = NULL;
	if (info->appsrc) {
		/* Will call appsrc_destroyed. */
		gst_app_src_set_callbacks (info->appsrc, &null_src_cb,
				NULL, NULL);
	}
	if (info->appsink) {
		/* Will call appsink_destroyed. */
		gst_app_sink_set_callbacks (info->appsink, &null_sink_cb,
				NULL, NULL);
	}

	/* Make sure no other thread is using the structure */
	g_free (info->session_id);
	g_free (info->participant);

	/* This lets the potential read or write callbacks waiting for appdata_mutex
	 * know the info structure has been destroyed. */
	info->readable_cb_token = 0;
	info->writable_cb_token = 0;

	g_clear_handle_id(&info->readable_timer_id, g_source_remove);
	g_clear_handle_id(&info->writable_timer_id, g_source_remove);

	g_clear_pointer(&info->current_sample, gst_sample_unref);

	/* Unblock any reading thread before destroying the GCond */
	g_cond_broadcast (&info->readable_cond);

	g_cond_clear (&info->readable_cond);

	g_slice_free (PurpleMediaAppDataInfo, info);
}

/*
 * Get an app data info struct associated with a session and lock the mutex
 * We don't want to return an info struct and unlock then it gets destroyed
 * so we need to return it with the lock still taken
 */
static PurpleMediaAppDataInfo *
get_app_data_info_and_lock (PurpleMediaManager *manager,
	PurpleMedia *media, const gchar *session_id, const gchar *participant)
{
	GList *i;

	g_mutex_lock (&manager->priv->appdata_mutex);
	for (i = manager->priv->appdata_info; i; i = i->next) {
		PurpleMediaAppDataInfo *info = i->data;

		if (info->media == media &&
			purple_strequal (info->session_id, session_id) &&
			(participant == NULL ||
				purple_strequal (info->participant, participant))) {
			return info;
		}
	}

	return NULL;
}

/*
 * Get an app data info struct associated with a session and lock the mutex
 * if it doesn't exist, we create it.
 */
static PurpleMediaAppDataInfo *
ensure_app_data_info_and_lock (PurpleMediaManager *manager, PurpleMedia *media,
	const gchar *session_id, const gchar *participant)
{
	PurpleMediaAppDataInfo * info = get_app_data_info_and_lock (manager, media,
		session_id, participant);

	if (info == NULL) {
		info = g_slice_new0 (PurpleMediaAppDataInfo);
		info->media = media;
		g_weak_ref_init (&info->media_ref, media);
		info->session_id = g_strdup (session_id);
		info->participant = g_strdup (participant);
		g_cond_init (&info->readable_cond);
		manager->priv->appdata_info = g_list_prepend (
			manager->priv->appdata_info, info);
	}

	return info;
}


static void
request_pad_unlinked_cb(GstPad *pad, G_GNUC_UNUSED GstPad *peer,
                        G_GNUC_UNUSED gpointer user_data)
{
	GstElement *parent = GST_ELEMENT_PARENT(pad);
	GstIterator *iter;
	GValue tmp = G_VALUE_INIT;
	GstIteratorResult result;

	gst_element_release_request_pad(parent, pad);

	iter = gst_element_iterate_src_pads(parent);

	result = gst_iterator_next(iter, &tmp);

	if (result == GST_ITERATOR_DONE) {
		gst_element_set_locked_state(parent, TRUE);
		gst_element_set_state(parent, GST_STATE_NULL);
		gst_bin_remove(GST_BIN(GST_ELEMENT_PARENT(parent)), parent);
	} else if (result == GST_ITERATOR_OK) {
		g_value_reset(&tmp);
	}

	gst_iterator_free(iter);
}

static void
nonunique_src_unlinked_cb(GstPad *pad, G_GNUC_UNUSED GstPad *peer,
                          G_GNUC_UNUSED gpointer user_data)
{
	GstElement *element = GST_ELEMENT_PARENT(pad);
	gst_element_set_locked_state(element, TRUE);
	gst_element_set_state(element, GST_STATE_NULL);
	gst_bin_remove(GST_BIN(GST_ELEMENT_PARENT(element)), element);
}

void
purple_media_manager_set_video_caps(PurpleMediaManager *manager, GstCaps *caps)
{
	g_clear_pointer(&manager->priv->video_caps, gst_caps_unref);

	manager->priv->video_caps = caps;

	if (manager->priv->pipeline && manager->priv->video_src) {
		gchar *id = purple_media_element_info_get_id(manager->priv->video_src);
		GstElement *src = gst_bin_get_by_name(GST_BIN(manager->priv->pipeline), id);

		if (src) {
			GstElement *capsfilter = gst_bin_get_by_name(GST_BIN(src), "protocol_video_caps");
			if (capsfilter) {
				g_object_set(G_OBJECT(capsfilter), "caps", caps, NULL);
				gst_object_unref (capsfilter);
			}
			gst_object_unref (src);
		}

		g_free(id);
	}
}

GstCaps *
purple_media_manager_get_video_caps(PurpleMediaManager *manager)
{
	if (manager->priv->video_caps == NULL) {
		manager->priv->video_caps = gst_caps_from_string("video/x-raw,"
			"width=[250,352], height=[200,288], framerate=[1/1,20/1]");
	}

	return manager->priv->video_caps;
}

/*
 * Calls the appdata writable callback from the main thread.
 * This needs to grab the appdata lock and make sure it didn't get destroyed
 * before calling the callback.
 */
static gboolean
appsrc_writable (gpointer user_data)
{
	PurpleMediaManager *manager = purple_media_manager_get ();
	PurpleMediaAppDataInfo *info = user_data;
	void (*writable_cb) (PurpleMediaManager *manager, PurpleMedia *media,
		const gchar *session_id, const gchar *participant, gboolean writable,
		gpointer user_data);
	PurpleMedia *media;
	gchar *session_id;
	gchar *participant;
	gboolean writable;
	gpointer cb_data;
	guint *cb_token_ptr = &info->writable_cb_token;
	guint cb_token = *cb_token_ptr;


	g_mutex_lock (&manager->priv->appdata_mutex);
	if (cb_token == 0 || cb_token != *cb_token_ptr) {
		/* In case info was freed while we were waiting for the mutex to unlock
		 * we still have a pointer to the cb_token which should still be
		 * accessible since it's in the Glib slice allocator. It gets set to 0
		 * just after the timeout is canceled which happens also before the
		 * AppDataInfo is freed, so even if that memory slice gets reused, the
		 * cb_token would be different from its previous value (unless
		 * extremely unlucky). So checking if the value for the cb_token changed
		 * should be enough to prevent any kind of race condition in which the
		 * media/AppDataInfo gets destroyed in one thread while the timeout was
		 * triggered and is waiting on the mutex to get unlocked in this thread
		 */
		g_mutex_unlock (&manager->priv->appdata_mutex);
		return FALSE;
	}
	writable_cb = info->callbacks.writable;
	media = g_weak_ref_get (&info->media_ref);
	session_id = g_strdup (info->session_id);
	participant = g_strdup (info->participant);
	writable = info->writable && info->connected;
	cb_data = info->user_data;

	info->writable_cb_token = 0;
	g_mutex_unlock (&manager->priv->appdata_mutex);


	if (writable_cb && media) {
		writable_cb (manager, media, session_id, participant, writable,
			cb_data);
	}

	g_object_unref (media);
	g_free (session_id);
	g_free (participant);

	return FALSE;
}

/*
 * Schedule a writable callback to be called from the main thread.
 * We need to do this because need-data/enough-data signals from appsrc
 * will come from the streaming thread and we need to create
 * a source that we attach to the main context but we can't use
 * g_main_context_invoke since we need to be able to cancel the source if the
 * media gets destroyed.
 * We use a timeout source instead of idle source, so the callback gets a higher
 * priority
 */
static void
call_appsrc_writable_locked (PurpleMediaAppDataInfo *info)
{
	PurpleMediaManager *manager = purple_media_manager_get ();

	/* We already have a writable callback scheduled, don't create another one */
	if (info->writable_cb_token || info->callbacks.writable == NULL) {
		return;
	}

	/* We can't use writable_timer_id as a token, because the timeout is added
	 * into libpurple's main event loop, which runs in a different thread than
	 * from where call_appsrc_writable_locked() was called. Consequently, the
	 * callback may run even before g_timeout_add() returns the timer ID
	 * to us. */
	info->writable_cb_token = ++manager->priv->appdata_cb_token;
	info->writable_timer_id = g_timeout_add (0, appsrc_writable, info);
}

static void
appsrc_need_data(G_GNUC_UNUSED GstAppSrc *appsrc, G_GNUC_UNUSED guint length,
                 gpointer user_data)
{
	PurpleMediaAppDataInfo *info = user_data;
	PurpleMediaManager *manager = purple_media_manager_get ();

	g_mutex_lock (&manager->priv->appdata_mutex);
	if (!info->writable) {
		info->writable = TRUE;
		/* Only signal writable if we also established a connection */
		if (info->connected) {
			call_appsrc_writable_locked (info);
		}
	}
	g_mutex_unlock (&manager->priv->appdata_mutex);
}

static void
appsrc_enough_data(G_GNUC_UNUSED GstAppSrc *appsrc, gpointer user_data)
{
	PurpleMediaAppDataInfo *info = user_data;
	PurpleMediaManager *manager = purple_media_manager_get ();

	g_mutex_lock (&manager->priv->appdata_mutex);
	if (info->writable) {
		info->writable = FALSE;
		call_appsrc_writable_locked (info);
	}
	g_mutex_unlock (&manager->priv->appdata_mutex);
}

static gboolean
appsrc_seek_data(G_GNUC_UNUSED GstAppSrc *appsrc, G_GNUC_UNUSED guint64 offset,
                 G_GNUC_UNUSED gpointer user_data)
{
	return FALSE;
}

static void
appsrc_destroyed (PurpleMediaAppDataInfo *info)
{
	PurpleMediaManager *manager;

	if (!info->media) {
		/* PurpleMediaAppDataInfo is being freed. Return at once. */
		return;
	}

	manager = purple_media_manager_get ();

	g_mutex_lock (&manager->priv->appdata_mutex);
	info->appsrc = NULL;
	if (info->writable) {
		info->writable = FALSE;
		call_appsrc_writable_locked (info);
	}
	g_mutex_unlock (&manager->priv->appdata_mutex);
}

static void
media_established_cb(G_GNUC_UNUSED PurpleMedia *media,
                     G_GNUC_UNUSED const char *session_id,
                     G_GNUC_UNUSED const char *participant,
                     G_GNUC_UNUSED PurpleMediaCandidate *local_candidate,
                     G_GNUC_UNUSED PurpleMediaCandidate *remote_candidate,
                     PurpleMediaAppDataInfo *info)
{
	PurpleMediaManager *manager = purple_media_manager_get ();

	g_mutex_lock (&manager->priv->appdata_mutex);
	info->connected = TRUE;
	/* We established the connection, if we were writable, then we need to
	 * signal it now */
	if (info->writable) {
		call_appsrc_writable_locked (info);
	}
	g_mutex_unlock (&manager->priv->appdata_mutex);
}

static GstElement *
create_send_appsrc(G_GNUC_UNUSED PurpleMediaElementInfo *element_info,
                   PurpleMedia *media, const char *session_id,
                   const char *participant)
{
	PurpleMediaManager *manager = purple_media_manager_get ();
	PurpleMediaAppDataInfo * info = ensure_app_data_info_and_lock (manager,
		media, session_id, participant);
	GstElement *appsrc = (GstElement *)info->appsrc;

	if (appsrc == NULL) {
		GstAppSrcCallbacks callbacks = {
			.need_data = appsrc_need_data,
			.enough_data = appsrc_enough_data,
			.seek_data = appsrc_seek_data,
		};
		GstCaps *caps = gst_caps_new_empty_simple ("application/octet-stream");

		appsrc = gst_element_factory_make("appsrc", NULL);

		info->appsrc = (GstAppSrc *)appsrc;

		gst_app_src_set_caps (info->appsrc, caps);
		gst_app_src_set_callbacks (info->appsrc,
			&callbacks, info, (GDestroyNotify) appsrc_destroyed);
		g_signal_connect (media, "candidate-pair-established",
			(GCallback) media_established_cb, info);
		gst_caps_unref (caps);
	}

	g_mutex_unlock (&manager->priv->appdata_mutex);
	return appsrc;
}

static void
appsink_eos(G_GNUC_UNUSED GstAppSink *appsink,
            G_GNUC_UNUSED gpointer user_data)
{
}

static GstFlowReturn
appsink_new_preroll(G_GNUC_UNUSED GstAppSink *appsink,
                    G_GNUC_UNUSED gpointer user_data)
{
	return GST_FLOW_OK;
}

static gboolean
appsink_readable (gpointer user_data)
{
	PurpleMediaManager *manager = purple_media_manager_get ();
	PurpleMediaAppDataInfo *info = user_data;
	void (*readable_cb) (PurpleMediaManager *manager, PurpleMedia *media,
		const gchar *session_id, const gchar *participant, gpointer user_data);
	PurpleMedia *media;
	gchar *session_id;
	gchar *participant;
	gpointer cb_data;
	guint *cb_token_ptr = &info->readable_cb_token;
	guint cb_token = *cb_token_ptr;
	gboolean run_again = FALSE;

	g_mutex_lock (&manager->priv->appdata_mutex);
	if (cb_token == 0 || cb_token != *cb_token_ptr) {
		/* Avoided a race condition (see writable callback) */
		g_mutex_unlock (&manager->priv->appdata_mutex);
		return FALSE;
	}

	if (info->callbacks.readable &&
		(info->num_samples > 0 || info->current_sample != NULL)) {
		readable_cb = info->callbacks.readable;
		media = g_weak_ref_get (&info->media_ref);
		session_id = g_strdup (info->session_id);
		participant = g_strdup (info->participant);
		cb_data = info->user_data;
		g_mutex_unlock (&manager->priv->appdata_mutex);

		readable_cb(manager, media, session_id, participant, cb_data);

		g_mutex_lock (&manager->priv->appdata_mutex);
		g_object_unref (media);
		g_free (session_id);
		g_free (participant);
		if (cb_token != *cb_token_ptr) {
			/* We got cancelled */
			g_mutex_unlock (&manager->priv->appdata_mutex);
			return FALSE;
		}
	}

	/* Do we still have samples? Schedule appsink_readable again. We break here
	 * so that other events get a chance to be processed too. */
	if (info->num_samples > 0 || info->current_sample != NULL) {
		run_again = TRUE;
	} else {
		info->readable_cb_token = 0;
	}

	g_mutex_unlock (&manager->priv->appdata_mutex);
	return run_again;
}

static void
call_appsink_readable_locked (PurpleMediaAppDataInfo *info)
{
	PurpleMediaManager *manager = purple_media_manager_get ();

	/* We must signal that a new sample has arrived to release blocking reads */
	g_cond_broadcast (&info->readable_cond);

	/* We already have a writable callback scheduled, don't create another one */
	if (info->readable_cb_token || info->callbacks.readable == NULL) {
		return;
	}

	info->readable_cb_token = ++manager->priv->appdata_cb_token;
	info->readable_timer_id = g_timeout_add (0, appsink_readable, info);
}

static GstFlowReturn
appsink_new_sample(G_GNUC_UNUSED GstAppSink *appsink, gpointer user_data)
{
	PurpleMediaManager *manager = purple_media_manager_get ();
	PurpleMediaAppDataInfo *info = user_data;

	g_mutex_lock (&manager->priv->appdata_mutex);
	info->num_samples++;
	call_appsink_readable_locked (info);
	g_mutex_unlock (&manager->priv->appdata_mutex);

	return GST_FLOW_OK;
}

static void
appsink_destroyed (PurpleMediaAppDataInfo *info)
{
	PurpleMediaManager *manager;

	if (!info->media) {
		/* PurpleMediaAppDataInfo is being freed. Return at once. */
		return;
	}

	manager = purple_media_manager_get ();

	g_mutex_lock (&manager->priv->appdata_mutex);
	info->appsink = NULL;
	info->num_samples = 0;
	g_mutex_unlock (&manager->priv->appdata_mutex);
}

static GstElement *
create_recv_appsink(G_GNUC_UNUSED PurpleMediaElementInfo *element_info,
                    PurpleMedia *media, const char *session_id,
                    const char *participant)
{
	PurpleMediaManager *manager = purple_media_manager_get ();
	PurpleMediaAppDataInfo * info = ensure_app_data_info_and_lock (manager,
		media, session_id, participant);
	GstElement *appsink = (GstElement *)info->appsink;

	if (appsink == NULL) {
		GstAppSinkCallbacks callbacks = {
			.eos = appsink_eos,
			.new_preroll = appsink_new_preroll,
			.new_sample = appsink_new_sample,
		};
		GstCaps *caps = gst_caps_new_empty_simple ("application/octet-stream");

		appsink = gst_element_factory_make("appsink", NULL);

		info->appsink = (GstAppSink *)appsink;

		gst_app_sink_set_caps (info->appsink, caps);
		gst_app_sink_set_callbacks (info->appsink,
			&callbacks, info, (GDestroyNotify) appsink_destroyed);
		gst_caps_unref (caps);

	}

	g_mutex_unlock (&manager->priv->appdata_mutex);
	return appsink;
}

static PurpleMediaElementInfo *
get_send_application_element_info(void)
{
	static PurpleMediaElementInfo *info = NULL;

	if (info == NULL) {
		info = g_object_new(PURPLE_TYPE_MEDIA_ELEMENT_INFO,
			"id", "pidginappsrc",
			"name", "Pidgin Application Source",
			"type", PURPLE_MEDIA_ELEMENT_APPLICATION
					| PURPLE_MEDIA_ELEMENT_SRC
					| PURPLE_MEDIA_ELEMENT_ONE_SRC,
			"create-cb", create_send_appsrc, NULL);
	}

	return info;
}

static PurpleMediaElementInfo *
get_recv_application_element_info(void)
{
	static PurpleMediaElementInfo *info = NULL;

	if (info == NULL) {
		info = g_object_new(PURPLE_TYPE_MEDIA_ELEMENT_INFO,
			"id", "pidginappsink",
			"name", "Pidgin Application Sink",
			"type", PURPLE_MEDIA_ELEMENT_APPLICATION
					| PURPLE_MEDIA_ELEMENT_SINK
					| PURPLE_MEDIA_ELEMENT_ONE_SINK,
			"create-cb", create_recv_appsink, NULL);
	}

	return info;
}

GstElement *
purple_media_manager_get_element(PurpleMediaManager *manager,
		PurpleMediaSessionType type, PurpleMedia *media,
		const gchar *session_id, const gchar *participant)
{
	GstElement *ret = NULL;
	PurpleMediaElementInfo *info = NULL;
	PurpleMediaElementType element_type;

	if (type & PURPLE_MEDIA_SEND_AUDIO) {
		info = manager->priv->audio_src;
	} else if (type & PURPLE_MEDIA_RECV_AUDIO) {
		info = manager->priv->audio_sink;
	} else if (type & PURPLE_MEDIA_SEND_VIDEO) {
		info = manager->priv->video_src;
	} else if (type & PURPLE_MEDIA_RECV_VIDEO) {
		info = manager->priv->video_sink;
	} else if (type & PURPLE_MEDIA_SEND_APPLICATION) {
		info = get_send_application_element_info ();
	} else if (type & PURPLE_MEDIA_RECV_APPLICATION) {
		info = get_recv_application_element_info ();
	}

	if (info == NULL) {
		return NULL;
	}

	element_type = purple_media_element_info_get_element_type(info);

	if (element_type & PURPLE_MEDIA_ELEMENT_UNIQUE &&
			element_type & PURPLE_MEDIA_ELEMENT_SRC) {
		GstElement *tee;
		GstPad *pad;
		GstPad *ghost;
		gchar *id = purple_media_element_info_get_id(info);

		ret = gst_bin_get_by_name(GST_BIN(
				purple_media_manager_get_pipeline(
				manager)), id);

		if (ret == NULL) {
			GstElement *bin, *fakesink;
			ret = purple_media_element_info_call_create(info,
					media, session_id, participant);
			bin = gst_bin_new(id);
			tee = gst_element_factory_make("tee", "tee");
			gst_bin_add_many(GST_BIN(bin), ret, tee, NULL);

			if (type & PURPLE_MEDIA_SEND_VIDEO) {
				GstElement *videoscale;
				GstElement *capsfilter;

				videoscale = gst_element_factory_make("videoscale", NULL);
				capsfilter = gst_element_factory_make("capsfilter", "protocol_video_caps");

				g_object_set(G_OBJECT(capsfilter),
					"caps", purple_media_manager_get_video_caps(manager), NULL);

				gst_bin_add_many(GST_BIN(bin), videoscale, capsfilter, NULL);
				gst_element_link_many(ret, videoscale, capsfilter, tee, NULL);
			} else {
				gst_element_link(ret, tee);
			}

			/*
			 * This shouldn't be necessary, but it stops it from
			 * giving a not-linked error upon destruction
			 */
			fakesink = gst_element_factory_make("fakesink", NULL);
			g_object_set(fakesink,
				"async", FALSE,
				"sync", FALSE,
				"enable-last-sample", FALSE,
				NULL);
			gst_bin_add(GST_BIN(bin), fakesink);
			gst_element_link(tee, fakesink);

			ret = bin;
			gst_object_ref(ret);
			gst_bin_add(GST_BIN(purple_media_manager_get_pipeline(
					manager)), ret);
		}
		g_free(id);

		tee = gst_bin_get_by_name(GST_BIN(ret), "tee");
#if GST_CHECK_VERSION(1, 19, 1)
		pad = gst_element_request_pad_simple(tee, "src_%u");
#else
		pad = gst_element_get_request_pad(tee, "src_%u");
#endif
		gst_object_unref(tee);
		ghost = gst_ghost_pad_new(NULL, pad);
		gst_object_unref(pad);
		g_signal_connect(GST_PAD(ghost), "unlinked",
				G_CALLBACK(request_pad_unlinked_cb), NULL);
		gst_pad_set_active(ghost, TRUE);
		gst_element_add_pad(ret, ghost);
	} else {
		ret = purple_media_element_info_call_create(info,
				media, session_id, participant);
		if (element_type & PURPLE_MEDIA_ELEMENT_SRC) {
			GstPad *pad = gst_element_get_static_pad(ret, "src");
			g_signal_connect(pad, "unlinked",
					G_CALLBACK(nonunique_src_unlinked_cb), NULL);
			gst_object_unref(pad);
			gst_object_ref(ret);
			gst_bin_add(GST_BIN(purple_media_manager_get_pipeline(manager)),
				ret);
		}
	}

	if (ret == NULL) {
		purple_debug_error("media", "Error creating source or sink\n");
	}

	return ret;
}

PurpleMediaElementInfo *
purple_media_manager_get_element_info(PurpleMediaManager *manager,
		const gchar *id)
{
	GList *iter;

	g_return_val_if_fail(PURPLE_IS_MEDIA_MANAGER(manager), NULL);
	g_return_val_if_fail(id != NULL, NULL);

	iter = manager->priv->elements;

	for (; iter; iter = g_list_next(iter)) {
		gchar *element_id = purple_media_element_info_get_id(iter->data);
		if (purple_strequal(element_id, id)) {
			g_free(element_id);
			g_object_ref(iter->data);
			return iter->data;
		}
		g_free(element_id);
	}

	return NULL;
}

static GQuark
element_info_to_detail(PurpleMediaElementInfo *info)
{
	PurpleMediaElementType type;

	type = purple_media_element_info_get_element_type(info);

	if (type & PURPLE_MEDIA_ELEMENT_AUDIO) {
		if (type & PURPLE_MEDIA_ELEMENT_SRC) {
			return g_quark_from_string("audiosrc");
		} else if (type & PURPLE_MEDIA_ELEMENT_SINK) {
			return g_quark_from_string("audiosink");
		}
	} else if (type & PURPLE_MEDIA_ELEMENT_VIDEO) {
		if (type & PURPLE_MEDIA_ELEMENT_SRC) {
			return g_quark_from_string("videosrc");
		} else if (type & PURPLE_MEDIA_ELEMENT_SINK) {
			return g_quark_from_string("videosink");
		}
	}

	return 0;
}

gboolean
purple_media_manager_register_element(PurpleMediaManager *manager,
		PurpleMediaElementInfo *info)
{
	PurpleMediaElementInfo *info2;
	gchar *id;
	GQuark detail;

	g_return_val_if_fail(PURPLE_IS_MEDIA_MANAGER(manager), FALSE);
	g_return_val_if_fail(info != NULL, FALSE);

	id = purple_media_element_info_get_id(info);
	info2 = purple_media_manager_get_element_info(manager, id);
	g_free(id);

	if (info2 != NULL) {
		g_object_unref(info2);
		return FALSE;
	}

	manager->priv->elements = g_list_prepend(manager->priv->elements, info);

	detail = element_info_to_detail(info);
	if (detail != 0) {
		g_signal_emit(manager,
				purple_media_manager_signals[ELEMENTS_CHANGED],
				detail);
	}

	return TRUE;
}

gboolean
purple_media_manager_unregister_element(PurpleMediaManager *manager,
		const gchar *id)
{
	PurpleMediaElementInfo *info;
	GQuark detail;

	g_return_val_if_fail(PURPLE_IS_MEDIA_MANAGER(manager), FALSE);

	info = purple_media_manager_get_element_info(manager, id);

	if (info == NULL) {
		g_object_unref(info);
		return FALSE;
	}

	if (manager->priv->audio_src == info) {
		manager->priv->audio_src = NULL;
	}
	if (manager->priv->audio_sink == info) {
		manager->priv->audio_sink = NULL;
	}
	if (manager->priv->video_src == info) {
		manager->priv->video_src = NULL;
	}
	if (manager->priv->video_sink == info) {
		manager->priv->video_sink = NULL;
	}

	detail = element_info_to_detail(info);

	manager->priv->elements = g_list_remove(
			manager->priv->elements, info);
	g_object_unref(info);

	if (detail != 0) {
		g_signal_emit(manager,
				purple_media_manager_signals[ELEMENTS_CHANGED],
				detail);
	}

	return TRUE;
}

gboolean
purple_media_manager_set_active_element(PurpleMediaManager *manager,
		PurpleMediaElementInfo *info)
{
	PurpleMediaElementInfo *info2;
	PurpleMediaElementType type;
	gboolean ret = FALSE;
	gchar *id;

	g_return_val_if_fail(PURPLE_IS_MEDIA_MANAGER(manager), FALSE);
	g_return_val_if_fail(info != NULL, FALSE);

	id = purple_media_element_info_get_id(info);
	info2 = purple_media_manager_get_element_info(manager, id);
	g_free(id);

	if (info2 == NULL) {
		purple_media_manager_register_element(manager, info);
	} else {
		g_object_unref(info2);
	}

	type = purple_media_element_info_get_element_type(info);

	if (type & PURPLE_MEDIA_ELEMENT_SRC) {
		if (type & PURPLE_MEDIA_ELEMENT_AUDIO) {
			manager->priv->audio_src = info;
			ret = TRUE;
		}
		if (type & PURPLE_MEDIA_ELEMENT_VIDEO) {
			manager->priv->video_src = info;
			ret = TRUE;
		}
	}
	if (type & PURPLE_MEDIA_ELEMENT_SINK) {
		if (type & PURPLE_MEDIA_ELEMENT_AUDIO) {
			manager->priv->audio_sink = info;
			ret = TRUE;
		}
		if (type & PURPLE_MEDIA_ELEMENT_VIDEO) {
			manager->priv->video_sink = info;
			ret = TRUE;
		}
	}

	return ret;
}

PurpleMediaElementInfo *
purple_media_manager_get_active_element(PurpleMediaManager *manager,
		PurpleMediaElementType type)
{
	g_return_val_if_fail(PURPLE_IS_MEDIA_MANAGER(manager), NULL);

	if (type & PURPLE_MEDIA_ELEMENT_SRC) {
		if (type & PURPLE_MEDIA_ELEMENT_AUDIO) {
			return manager->priv->audio_src;
		} else if (type & PURPLE_MEDIA_ELEMENT_VIDEO) {
			return manager->priv->video_src;
		} else if (type & PURPLE_MEDIA_ELEMENT_APPLICATION) {
			return get_send_application_element_info ();
		}
	} else if (type & PURPLE_MEDIA_ELEMENT_SINK) {
		if (type & PURPLE_MEDIA_ELEMENT_AUDIO) {
			return manager->priv->audio_sink;
		} else if (type & PURPLE_MEDIA_ELEMENT_VIDEO) {
			return manager->priv->video_sink;
		} else if (type & PURPLE_MEDIA_ELEMENT_APPLICATION) {
			return get_recv_application_element_info ();
		}
	}

	return NULL;
}

gboolean
purple_media_manager_create_output_window(PurpleMediaManager *manager,
		PurpleMedia *media, const gchar *session_id,
		const gchar *participant)
{
	GList *iter;

	g_return_val_if_fail(PURPLE_IS_MEDIA(media), FALSE);

	iter = manager->priv->output_windows;
	for(; iter; iter = g_list_next(iter)) {
		PurpleMediaOutputWindow *ow = iter->data;

		if (ow->sink == NULL && ow->media == media &&
				purple_strequal(participant, ow->participant) &&
				purple_strequal(session_id, ow->session_id)) {
			GstElement *queue, *convert, *scale;
			GstElement *tee = purple_media_get_tee(media,
					session_id, participant);

			if (tee == NULL) {
				continue;
			}

			queue = gst_element_factory_make("queue", NULL);
			convert = gst_element_factory_make("videoconvert", NULL);
			scale = gst_element_factory_make("videoscale", NULL);
			ow->sink = purple_media_manager_get_element(
					manager, PURPLE_MEDIA_RECV_VIDEO,
					ow->media, ow->session_id,
					ow->participant);

			if (participant == NULL) {
				/* aka this is a preview sink */
				GObjectClass *klass =
						G_OBJECT_GET_CLASS(ow->sink);
				if (g_object_class_find_property(klass, "sync")) {
					g_object_set(G_OBJECT(ow->sink),
							"sync", FALSE, NULL);
				}
				if (g_object_class_find_property(klass, "async")) {
					g_object_set(G_OBJECT(ow->sink),
							"async", FALSE, NULL);
				}
			}

			gst_bin_add_many(GST_BIN(GST_ELEMENT_PARENT(tee)),
					queue, convert, scale, ow->sink, NULL);

			gst_element_set_state(ow->sink, GST_STATE_PLAYING);
			gst_element_set_state(scale, GST_STATE_PLAYING);
			gst_element_set_state(convert, GST_STATE_PLAYING);
			gst_element_set_state(queue, GST_STATE_PLAYING);
			gst_element_link(scale, ow->sink);
			gst_element_link(convert, scale);
			gst_element_link(queue, convert);
			gst_element_link(tee, queue);
		}
	}
	return TRUE;
}

gulong
purple_media_manager_set_output_window(PurpleMediaManager *manager,
		PurpleMedia *media, const gchar *session_id,
		const gchar *participant)
{
	PurpleMediaOutputWindow *output_window;

	g_return_val_if_fail(PURPLE_IS_MEDIA_MANAGER(manager), FALSE);
	g_return_val_if_fail(PURPLE_IS_MEDIA(media), FALSE);

	output_window = g_new0(PurpleMediaOutputWindow, 1);
	output_window->id = manager->priv->next_output_window_id++;
	output_window->media = media;
	output_window->session_id = g_strdup(session_id);
	output_window->participant = g_strdup(participant);

	manager->priv->output_windows = g_list_prepend(
			manager->priv->output_windows, output_window);

	if (purple_media_get_tee(media, session_id, participant) != NULL) {
		purple_media_manager_create_output_window(manager,
				media, session_id, participant);
	}

	return output_window->id;
}

gboolean
purple_media_manager_remove_output_window(PurpleMediaManager *manager,
		gulong output_window_id)
{
	PurpleMediaOutputWindow *output_window = NULL;
	GList *iter;

	g_return_val_if_fail(PURPLE_IS_MEDIA_MANAGER(manager), FALSE);

	iter = manager->priv->output_windows;
	for (; iter; iter = g_list_next(iter)) {
		PurpleMediaOutputWindow *ow = iter->data;
		if (ow->id == output_window_id) {
			manager->priv->output_windows = g_list_delete_link(
					manager->priv->output_windows, iter);
			output_window = ow;
			break;
		}
	}

	if (output_window == NULL) {
		return FALSE;
	}

	if (output_window->sink != NULL) {
		GstElement *element = output_window->sink;
		GstPad *teepad = NULL;
		GSList *to_remove = NULL;

		/* Find the tee element this output is connected to. */
		while (!teepad) {
			GstPad *pad;
			GstPad *peer;
			GstElementFactory *factory;
			const gchar *factory_name;

			to_remove = g_slist_append(to_remove, element);

			pad = gst_element_get_static_pad(element, "sink");
			peer = gst_pad_get_peer(pad);
			if (!peer) {
				/* Output is disconnected from the pipeline. */
				gst_object_unref(pad);
				break;
			}

			factory = gst_element_get_factory(GST_PAD_PARENT(peer));
			factory_name = gst_plugin_feature_get_name(factory);
			if (purple_strequal(factory_name, "tee")) {
				teepad = peer;
			}

			element = GST_PAD_PARENT(peer);

			gst_object_unref(pad);
			gst_object_unref(peer);
		}

		if (teepad) {
			gst_element_release_request_pad(GST_PAD_PARENT(teepad),
					teepad);
		}

		while (to_remove) {
			GstElement *element = to_remove->data;

			gst_element_set_locked_state(element, TRUE);
			gst_element_set_state(element, GST_STATE_NULL);
			gst_bin_remove(GST_BIN(GST_ELEMENT_PARENT(element)),
					element);
			to_remove = g_slist_delete_link(to_remove, to_remove);
		}
	}

	g_free(output_window->session_id);
	g_free(output_window->participant);
	g_free(output_window);

	return TRUE;
}

void
purple_media_manager_remove_output_windows(PurpleMediaManager *manager,
		PurpleMedia *media, const gchar *session_id,
		const gchar *participant)
{
	GList *iter;

	g_return_if_fail(PURPLE_IS_MEDIA(media));

	iter = manager->priv->output_windows;

	for (; iter;) {
		PurpleMediaOutputWindow *ow = iter->data;
		iter = g_list_next(iter);

		if (media == ow->media &&
				purple_strequal(session_id, ow->session_id) &&
				purple_strequal(participant, ow->participant))
		{
			purple_media_manager_remove_output_window(
					manager, ow->id);
		}
	}
}

void
purple_media_manager_set_ui_caps(PurpleMediaManager *manager,
		PurpleMediaCaps caps)
{
	PurpleMediaCaps oldcaps;

	g_return_if_fail(PURPLE_IS_MEDIA_MANAGER(manager));

	oldcaps = manager->priv->ui_caps;
	manager->priv->ui_caps = caps;

	if (caps != oldcaps) {
		g_signal_emit(manager,
				purple_media_manager_signals[UI_CAPS_CHANGED],
				0, caps, oldcaps);
	}
}

PurpleMediaCaps
purple_media_manager_get_ui_caps(PurpleMediaManager *manager)
{
	g_return_val_if_fail(PURPLE_IS_MEDIA_MANAGER(manager),
			PURPLE_MEDIA_CAPS_NONE);
	return manager->priv->ui_caps;
}

void
purple_media_manager_set_backend_type(PurpleMediaManager *manager,
		GType backend_type)
{
	g_return_if_fail(PURPLE_IS_MEDIA_MANAGER(manager));

	manager->priv->backend_type = backend_type;
}

GType
purple_media_manager_get_backend_type(PurpleMediaManager *manager)
{
	g_return_val_if_fail(PURPLE_IS_MEDIA_MANAGER(manager),
			PURPLE_MEDIA_CAPS_NONE);

	return manager->priv->backend_type;
}

void
purple_media_manager_set_application_data_callbacks(PurpleMediaManager *manager,
		PurpleMedia *media, const gchar *session_id,
		const gchar *participant, PurpleMediaAppDataCallbacks *callbacks,
		gpointer user_data, GDestroyNotify notify)
{
	PurpleMediaAppDataInfo * info = ensure_app_data_info_and_lock (manager,
		media, session_id, participant);

	if (info->notify) {
		info->notify (info->user_data);
	}

	g_clear_handle_id(&info->readable_cb_token, g_source_remove);
	g_clear_handle_id(&info->writable_cb_token, g_source_remove);

	if (callbacks) {
		info->callbacks = *callbacks;
	} else {
		info->callbacks.writable = NULL;
		info->callbacks.readable = NULL;
	}
	info->user_data = user_data;
	info->notify = notify;

	call_appsrc_writable_locked (info);
	if (info->num_samples > 0 || info->current_sample != NULL) {
		call_appsink_readable_locked (info);
	}

	g_mutex_unlock (&manager->priv->appdata_mutex);
}

gint
purple_media_manager_send_application_data (
	PurpleMediaManager *manager, PurpleMedia *media, const gchar *session_id,
	const gchar *participant, gpointer buffer, guint size, gboolean blocking)
{
	PurpleMediaAppDataInfo * info = get_app_data_info_and_lock (manager,
		media, session_id, participant);

	if (info && info->appsrc && info->connected) {
		GstBuffer *gstbuffer = gst_buffer_new_wrapped (g_memdup2(buffer, size),
			size);
		GstAppSrc *appsrc = gst_object_ref (info->appsrc);

		g_mutex_unlock (&manager->priv->appdata_mutex);
		if (gst_app_src_push_buffer (appsrc, gstbuffer) == GST_FLOW_OK) {
			if (blocking) {
				GstPad *srcpad;

				srcpad = gst_element_get_static_pad (GST_ELEMENT (appsrc),
					"src");
				if (srcpad) {
					gst_pad_peer_query (srcpad, gst_query_new_drain ());
					gst_object_unref (srcpad);
				}
			}
			gst_object_unref (appsrc);
			return size;
		} else {
			gst_object_unref (appsrc);
			return -1;
		}
	}
	g_mutex_unlock (&manager->priv->appdata_mutex);
	return -1;
}

gint
purple_media_manager_receive_application_data (
	PurpleMediaManager *manager, PurpleMedia *media, const gchar *session_id,
	const gchar *participant, gpointer buffer, guint max_size,
	gboolean blocking)
{
	PurpleMediaAppDataInfo * info = get_app_data_info_and_lock (manager,
		media, session_id, participant);
	guint bytes_read = 0;

	if (info) {
		/* If we are in a blocking read, we need to loop until max_size data
		 * is read into the buffer, if we're not, then we need to read as much
		 * data as possible
		 */
		do {
			if (!info->current_sample && info->appsink && info->num_samples > 0) {
				info->current_sample = gst_app_sink_pull_sample (info->appsink);
				info->sample_offset = 0;
				if (info->current_sample) {
					info->num_samples--;
				}
			}

			if (info->current_sample) {
				GstBuffer *gstbuffer = gst_sample_get_buffer (
					info->current_sample);

				if (gstbuffer) {
					GstMapInfo mapinfo;
					guint bytes_to_copy;

					gst_buffer_map (gstbuffer, &mapinfo, GST_MAP_READ);
					/* We must copy only the data remaining in the buffer without
					 * overflowing the buffer */
					bytes_to_copy = MIN(max_size - bytes_read,
					                    mapinfo.size - info->sample_offset);
					memcpy ((guint8 *)buffer + bytes_read,
						mapinfo.data + info->sample_offset,	bytes_to_copy);

					gst_buffer_unmap (gstbuffer, &mapinfo);
					info->sample_offset += bytes_to_copy;
					bytes_read += bytes_to_copy;
					if (info->sample_offset == mapinfo.size) {
						gst_sample_unref (info->current_sample);
						info->current_sample = NULL;
						info->sample_offset = 0;
					}
				} else {
					/* In case there's no buffer in the sample (should never
					 * happen), we need to at least unref it */
					gst_sample_unref (info->current_sample);
					info->current_sample = NULL;
					info->sample_offset = 0;
				}
			}

			/* If blocking, wait until there's an available sample */
			while (bytes_read < max_size && blocking &&
				info->current_sample == NULL && info->num_samples == 0) {
				g_cond_wait (&info->readable_cond, &manager->priv->appdata_mutex);

				/* We've been signaled, we need to unlock and regrab the info
				 * struct to make sure nothing changed */
				g_mutex_unlock (&manager->priv->appdata_mutex);
				info = get_app_data_info_and_lock (manager,
					media, session_id, participant);
				if (info == NULL || info->appsink == NULL) {
					/* The session was destroyed while we were waiting, we
					 * should return here */
					g_mutex_unlock (&manager->priv->appdata_mutex);
					return bytes_read;
				}
			}
		} while (bytes_read < max_size && (blocking || info->num_samples > 0));

		g_mutex_unlock (&manager->priv->appdata_mutex);
		return bytes_read;
	}
	g_mutex_unlock (&manager->priv->appdata_mutex);
	return -1;
}

static void
videosink_disable_last_sample(GstElement *sink)
{
	GObjectClass *klass = G_OBJECT_GET_CLASS(sink);

	if (g_object_class_find_property(klass, "enable-last-sample")) {
		g_object_set(sink, "enable-last-sample", FALSE, NULL);
	}
}

static PurpleMediaElementType
gst_class_to_purple_element_type(const gchar *device_class)
{
	if (purple_strequal(device_class, "Audio/Source")) {
		return PURPLE_MEDIA_ELEMENT_AUDIO
				| PURPLE_MEDIA_ELEMENT_SRC
				| PURPLE_MEDIA_ELEMENT_ONE_SRC
				| PURPLE_MEDIA_ELEMENT_UNIQUE;
	} else if (purple_strequal(device_class, "Audio/Sink")) {
		return PURPLE_MEDIA_ELEMENT_AUDIO
				| PURPLE_MEDIA_ELEMENT_SINK
				| PURPLE_MEDIA_ELEMENT_ONE_SINK;
	} else if (purple_strequal(device_class, "Video/Source")) {
		return PURPLE_MEDIA_ELEMENT_VIDEO
				| PURPLE_MEDIA_ELEMENT_SRC
				| PURPLE_MEDIA_ELEMENT_ONE_SRC
				| PURPLE_MEDIA_ELEMENT_UNIQUE;
	} else if (purple_strequal(device_class, "Video/Sink")) {
		return PURPLE_MEDIA_ELEMENT_VIDEO
				| PURPLE_MEDIA_ELEMENT_SINK
				| PURPLE_MEDIA_ELEMENT_ONE_SINK;
	}

	return PURPLE_MEDIA_ELEMENT_NONE;
}

static GstElement *
gst_device_create_cb(PurpleMediaElementInfo *info,
                     G_GNUC_UNUSED PurpleMedia *media,
                     G_GNUC_UNUSED const char *session_id,
                     G_GNUC_UNUSED const char *participant)
{
	GstDevice *device;
	GstElement *result;
	PurpleMediaElementType type;

	device = g_object_get_data(G_OBJECT(info), "gst-device");
	if (!device) {
		return NULL;
	}

	result = gst_device_create_element(device, NULL);
	if (!result) {
		return NULL;
	}

	type = purple_media_element_info_get_element_type(info);

	if ((type & PURPLE_MEDIA_ELEMENT_VIDEO) &&
	    (type & PURPLE_MEDIA_ELEMENT_SINK)) {
		videosink_disable_last_sample(result);
	}

	return result;
}

static gboolean
device_is_ignored(GstDevice *device)
{
	gboolean result = FALSE;

	gchar *device_class;

	g_return_val_if_fail(device, TRUE);

	device_class = gst_device_get_device_class(device);

	/* Ignore PulseAudio monitor audio sources since they have little use
	 * in the context of telephony.*/
	if (purple_strequal(device_class, "Audio/Source")) {
		GstStructure *properties;
		const gchar *pa_class;

		properties = gst_device_get_properties(device);

		pa_class = gst_structure_get_string(properties, "device.class");
		if (purple_strequal(pa_class, "monitor")) {
			result = TRUE;
		}

		gst_structure_free(properties);
	}

	g_free(device_class);

	return result;
}

static void
purple_media_manager_register_gst_device(PurpleMediaManager *manager,
		GstDevice *device)
{
	PurpleMediaElementInfo *info;
	PurpleMediaElementType type;
	gchar *name;
	gchar *device_class;
	gchar *id;

	if (device_is_ignored(device)) {
		return;
	}

	name = gst_device_get_display_name(device);
	device_class = gst_device_get_device_class(device);

	id = g_strdup_printf("%s %s", device_class, name);

	type = gst_class_to_purple_element_type(device_class);

	info = g_object_new(PURPLE_TYPE_MEDIA_ELEMENT_INFO,
			"id", id,
			"name", name,
			"type", type,
			"create-cb", gst_device_create_cb,
			NULL);

	g_object_set_data(G_OBJECT(info), "gst-device", device);

	purple_media_manager_register_element(manager, info);

	purple_debug_info("mediamanager", "Registered %s device %s",
			device_class, name);

	g_free(name);
	g_free(device_class);
	g_free(id);
}

static void
purple_media_manager_unregister_gst_device(PurpleMediaManager *manager,
		GstDevice *device)
{
	GList *i;
	gchar *name;
	gchar *device_class;
	gboolean done = FALSE;

	name = gst_device_get_display_name(device);
	device_class = gst_device_get_device_class(device);

	for (i = manager->priv->elements; i && !done; i = i->next) {
		PurpleMediaElementInfo *info = i->data;
		GstDevice *device2;

		device2 = g_object_get_data(G_OBJECT(info), "gst-device");
		if (device2) {
			gchar *name2;
			gchar *device_class2;

			name2 = gst_device_get_display_name(device2);
			device_class2 = gst_device_get_device_class(device2);

			if (purple_strequal(name, name2) &&
			    purple_strequal(device_class, device_class2)) {
				gchar *id;

				id = purple_media_element_info_get_id(info);
				purple_media_manager_unregister_element(manager,
						id);

				purple_debug_info("mediamanager",
						"Unregistered %s device %s",
						device_class, name);

				g_free(id);

				done = TRUE;
			}

			g_free(name2);
			g_free(device_class2);
		}
	}

	g_free(name);
	g_free(device_class);
}

static gboolean
device_monitor_bus_cb(G_GNUC_UNUSED GstBus *bus, GstMessage *message,
                      gpointer user_data)
{
	PurpleMediaManager *manager = user_data;
	GstMessageType message_type;
	GstDevice *device;

	message_type = GST_MESSAGE_TYPE(message);

	if (message_type == GST_MESSAGE_DEVICE_ADDED) {
		gst_message_parse_device_added(message, &device);
		purple_media_manager_register_gst_device(manager, device);
	} else if (message_type == GST_MESSAGE_DEVICE_REMOVED) {
		gst_message_parse_device_removed (message, &device);
		purple_media_manager_unregister_gst_device(manager, device);
	}

	return G_SOURCE_CONTINUE;
}

static void
purple_media_manager_init_device_monitor(PurpleMediaManager *manager)
{
	GstBus *bus;
	GList *i;

	manager->priv->device_monitor = gst_device_monitor_new();

	bus = gst_device_monitor_get_bus(manager->priv->device_monitor);
	gst_bus_add_watch (bus, device_monitor_bus_cb, manager);
	gst_object_unref (bus);

	/* This avoids warning in GStreamer logs about no filters set */
	gst_device_monitor_add_filter(manager->priv->device_monitor, NULL, NULL);

	gst_device_monitor_start(manager->priv->device_monitor);

	i = gst_device_monitor_get_devices(manager->priv->device_monitor);
	for (; i; i = g_list_delete_link(i, i)) {
		GstDevice *device = i->data;

		purple_media_manager_register_gst_device(manager, device);
		gst_object_unref(device);
	}
}

GList *
purple_media_manager_enumerate_elements(PurpleMediaManager *manager,
		PurpleMediaElementType type)
{
	GList *result = NULL;
	GList *i;

	for (i = manager->priv->elements; i; i = i->next) {
		PurpleMediaElementInfo *info = i->data;
		PurpleMediaElementType type2;

		type2 = purple_media_element_info_get_element_type(info);

		if ((type2 & type) == type) {
			g_object_ref(info);
			result = g_list_prepend(result, info);
		}
	}

	return result;
}

static GstElement *
gst_factory_make_cb(PurpleMediaElementInfo *info,
                    G_GNUC_UNUSED PurpleMedia *media,
                    G_GNUC_UNUSED const char *session_id,
                    G_GNUC_UNUSED const char *participant)
{
	gchar *id;
	GstElement *element;

	id = purple_media_element_info_get_id(info);

	element = gst_element_factory_make(id, NULL);

	g_free(id);

	return element;
}

static void
autovideosink_child_added_cb(G_GNUC_UNUSED GstChildProxy *child_proxy,
                             GObject *object, G_GNUC_UNUSED gchar *name,
                             G_GNUC_UNUSED gpointer user_data)
{
	videosink_disable_last_sample(GST_ELEMENT(object));
}

static GstElement *
default_video_sink_create_cb(G_GNUC_UNUSED PurpleMediaElementInfo *info,
                             G_GNUC_UNUSED PurpleMedia *media,
                             G_GNUC_UNUSED const char *session_id,
                             G_GNUC_UNUSED const char *participant)
{
	GstElement *videosink = gst_element_factory_make("autovideosink", NULL);

	g_signal_connect(videosink, "child-added",
			G_CALLBACK(autovideosink_child_added_cb), NULL);

	return videosink;
}

static GstElement *
disabled_video_create_cb(G_GNUC_UNUSED PurpleMediaElementInfo *info,
                         G_GNUC_UNUSED PurpleMedia *media,
                         G_GNUC_UNUSED const char *session_id,
                         G_GNUC_UNUSED const char *participant)
{
	GstElement *src = gst_element_factory_make("videotestsrc", NULL);

	/* GST_VIDEO_TEST_SRC_BLACK */
	g_object_set(src, "pattern", 2, NULL);

	return src;
}

static GstElement *
test_video_create_cb(G_GNUC_UNUSED PurpleMediaElementInfo *info,
                     G_GNUC_UNUSED PurpleMedia *media,
                     G_GNUC_UNUSED const char *session_id,
                     G_GNUC_UNUSED const char *participant)
{
	GstElement *src = gst_element_factory_make("videotestsrc", NULL);

	g_object_set(src, "is-live", TRUE, NULL);

	return src;
}

static void
purple_media_manager_register_static_elements(PurpleMediaManager *manager)
{
	static const gchar *VIDEO_SINK_PLUGINS[] = {
		"gtksink", "GTK",
		"gtkglsink", "GTK OpenGL",
		/* "aasink", "AALib", Didn't work for me */
		NULL
	};
	const gchar **sinks = NULL;

	/* Default auto* elements. */

	purple_media_manager_register_element(manager,
		g_object_new(PURPLE_TYPE_MEDIA_ELEMENT_INFO,
			"id", "autoaudiosrc",
			"name", N_("Default"),
			"type", PURPLE_MEDIA_ELEMENT_AUDIO
				| PURPLE_MEDIA_ELEMENT_SRC
				| PURPLE_MEDIA_ELEMENT_ONE_SRC
				| PURPLE_MEDIA_ELEMENT_UNIQUE,
			"create-cb", gst_factory_make_cb,
			NULL));

	purple_media_manager_register_element(manager,
		g_object_new(PURPLE_TYPE_MEDIA_ELEMENT_INFO,
			"id", "autoaudiosink",
			"name", N_("Default"),
			"type", PURPLE_MEDIA_ELEMENT_AUDIO
					| PURPLE_MEDIA_ELEMENT_SINK
					| PURPLE_MEDIA_ELEMENT_ONE_SINK,
			"create-cb", gst_factory_make_cb,
			NULL));

	purple_media_manager_register_element(manager,
		g_object_new(PURPLE_TYPE_MEDIA_ELEMENT_INFO,
			"id", "autovideosrc",
			"name", N_("Default"),
			"type", PURPLE_MEDIA_ELEMENT_VIDEO
				| PURPLE_MEDIA_ELEMENT_SRC
				| PURPLE_MEDIA_ELEMENT_ONE_SRC
				| PURPLE_MEDIA_ELEMENT_UNIQUE,
			"create-cb", gst_factory_make_cb,
			NULL));

	purple_media_manager_register_element(manager,
		g_object_new(PURPLE_TYPE_MEDIA_ELEMENT_INFO,
			"id", "autovideosink",
			"name", N_("Default"),
			"type", PURPLE_MEDIA_ELEMENT_VIDEO
				| PURPLE_MEDIA_ELEMENT_SINK
				| PURPLE_MEDIA_ELEMENT_ONE_SINK,
			"create-cb", default_video_sink_create_cb,
			NULL));

	/* Special elements */

	purple_media_manager_register_element(manager,
		g_object_new(PURPLE_TYPE_MEDIA_ELEMENT_INFO,
			"id", "audiotestsrc",
			/* Translators: This is a noun that refers to one
			 * possible audio input device. The device can help the
			 * user to check if her speakers or headphones have been
			 * set up correctly for voice calling. */
			"name", N_("Test Sound"),
			"type", PURPLE_MEDIA_ELEMENT_AUDIO
				| PURPLE_MEDIA_ELEMENT_SRC
				| PURPLE_MEDIA_ELEMENT_ONE_SRC,
			"create-cb", gst_factory_make_cb,
			NULL));

	purple_media_manager_register_element(manager,
		g_object_new(PURPLE_TYPE_MEDIA_ELEMENT_INFO,
			"id", "disabledvideosrc",
			"name", N_("Disabled"),
			"type", PURPLE_MEDIA_ELEMENT_VIDEO
				| PURPLE_MEDIA_ELEMENT_SRC
				| PURPLE_MEDIA_ELEMENT_ONE_SINK,
			"create-cb", disabled_video_create_cb,
			NULL));

	purple_media_manager_register_element(manager,
		g_object_new(PURPLE_TYPE_MEDIA_ELEMENT_INFO,
			"id", "videotestsrc",
			/* Translators: This is a noun that refers to one
			 * possible video input device. The device produces
			 * a test "monoscope" image that can help the user check
			 * the video output has been set up correctly without
			 * needing a webcam connected to the computer. */
			"name", N_("Test Pattern"),
			"type", PURPLE_MEDIA_ELEMENT_VIDEO
				| PURPLE_MEDIA_ELEMENT_SRC
				| PURPLE_MEDIA_ELEMENT_ONE_SRC,
			"create-cb", test_video_create_cb,
			NULL));

	for (sinks = VIDEO_SINK_PLUGINS; sinks[0]; sinks += 2) {
		GstElementFactory *factory;

		factory = gst_element_factory_find(sinks[0]);
		if (!factory) {
			continue;
		}

		purple_media_manager_register_element(manager,
			g_object_new(PURPLE_TYPE_MEDIA_ELEMENT_INFO,
				"id", sinks[0],
				"name", sinks[1],
				"type", PURPLE_MEDIA_ELEMENT_VIDEO
					| PURPLE_MEDIA_ELEMENT_SINK
					| PURPLE_MEDIA_ELEMENT_ONE_SINK,
				"create-cb", gst_factory_make_cb,
				NULL));

		gst_object_unref(factory);
	}
}

/*
 * PurpleMediaElementType
 */

GType
purple_media_element_type_get_type(void)
{
	static GType type = 0;
	if (type == 0) {
		static const GFlagsValue values[] = {
			{ PURPLE_MEDIA_ELEMENT_NONE,
				"PURPLE_MEDIA_ELEMENT_NONE", "none" },
			{ PURPLE_MEDIA_ELEMENT_AUDIO,
				"PURPLE_MEDIA_ELEMENT_AUDIO", "audio" },
			{ PURPLE_MEDIA_ELEMENT_VIDEO,
				"PURPLE_MEDIA_ELEMENT_VIDEO", "video" },
			{ PURPLE_MEDIA_ELEMENT_AUDIO_VIDEO,
				"PURPLE_MEDIA_ELEMENT_AUDIO_VIDEO",
				"audio-video" },
			{ PURPLE_MEDIA_ELEMENT_NO_SRCS,
				"PURPLE_MEDIA_ELEMENT_NO_SRCS", "no-srcs" },
			{ PURPLE_MEDIA_ELEMENT_ONE_SRC,
				"PURPLE_MEDIA_ELEMENT_ONE_SRC", "one-src" },
			{ PURPLE_MEDIA_ELEMENT_MULTI_SRC,
				"PURPLE_MEDIA_ELEMENT_MULTI_SRC",
				"multi-src" },
			{ PURPLE_MEDIA_ELEMENT_REQUEST_SRC,
				"PURPLE_MEDIA_ELEMENT_REQUEST_SRC",
				"request-src" },
			{ PURPLE_MEDIA_ELEMENT_NO_SINKS,
				"PURPLE_MEDIA_ELEMENT_NO_SINKS", "no-sinks" },
			{ PURPLE_MEDIA_ELEMENT_ONE_SINK,
				"PURPLE_MEDIA_ELEMENT_ONE_SINK", "one-sink" },
			{ PURPLE_MEDIA_ELEMENT_MULTI_SINK,
				"PURPLE_MEDIA_ELEMENT_MULTI_SINK",
				"multi-sink" },
			{ PURPLE_MEDIA_ELEMENT_REQUEST_SINK,
				"PURPLE_MEDIA_ELEMENT_REQUEST_SINK",
				"request-sink" },
			{ PURPLE_MEDIA_ELEMENT_UNIQUE,
				"PURPLE_MEDIA_ELEMENT_UNIQUE", "unique" },
			{ PURPLE_MEDIA_ELEMENT_SRC,
				"PURPLE_MEDIA_ELEMENT_SRC", "src" },
			{ PURPLE_MEDIA_ELEMENT_SINK,
				"PURPLE_MEDIA_ELEMENT_SINK", "sink" },
			{ PURPLE_MEDIA_ELEMENT_APPLICATION,
				"PURPLE_MEDIA_ELEMENT_APPLICATION", "application" },
			{ 0, NULL, NULL }
		};
		type = g_flags_register_static(
				"PurpleMediaElementType", values);
	}
	return type;
}

/*
 * PurpleMediaElementInfo
 */

struct _PurpleMediaElementInfoClass
{
	GObjectClass parent_class;
};

struct _PurpleMediaElementInfo
{
	GObject parent;
};

struct _PurpleMediaElementInfoPrivate
{
	gchar *id;
	gchar *name;
	PurpleMediaElementType type;
	PurpleMediaElementCreateCallback create;
};

enum {
	PROP_0,
	PROP_ID,
	PROP_NAME,
	PROP_TYPE,
	PROP_CREATE_CB,
};

G_DEFINE_TYPE_WITH_PRIVATE(PurpleMediaElementInfo,
		purple_media_element_info, G_TYPE_OBJECT);

static void
purple_media_element_info_init(PurpleMediaElementInfo *info)
{
	PurpleMediaElementInfoPrivate *priv =
			purple_media_element_info_get_instance_private(info);
	priv->id = NULL;
	priv->name = NULL;
	priv->type = PURPLE_MEDIA_ELEMENT_NONE;
	priv->create = NULL;
}

static void
purple_media_element_info_finalize(GObject *info)
{
	PurpleMediaElementInfoPrivate *priv =
			purple_media_element_info_get_instance_private(
					PURPLE_MEDIA_ELEMENT_INFO(info));
	g_free(priv->id);
	g_free(priv->name);

	G_OBJECT_CLASS(purple_media_element_info_parent_class)->finalize(info);
}

static void
purple_media_element_info_set_property (GObject *object, guint prop_id,
		const GValue *value, GParamSpec *pspec)
{
	PurpleMediaElementInfoPrivate *priv;
	g_return_if_fail(PURPLE_IS_MEDIA_ELEMENT_INFO(object));

	priv = purple_media_element_info_get_instance_private(
			PURPLE_MEDIA_ELEMENT_INFO(object));

	switch (prop_id) {
		case PROP_ID:
			g_free(priv->id);
			priv->id = g_value_dup_string(value);
			break;
		case PROP_NAME:
			g_free(priv->name);
			priv->name = g_value_dup_string(value);
			break;
		case PROP_TYPE: {
			priv->type = g_value_get_flags(value);
			break;
		}
		case PROP_CREATE_CB:
			priv->create = g_value_get_pointer(value);
			break;
		default:
			G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
			break;
	}
}

static void
purple_media_element_info_get_property (GObject *object, guint prop_id,
		GValue *value, GParamSpec *pspec)
{
	PurpleMediaElementInfoPrivate *priv;
	g_return_if_fail(PURPLE_IS_MEDIA_ELEMENT_INFO(object));

	priv = purple_media_element_info_get_instance_private(
			PURPLE_MEDIA_ELEMENT_INFO(object));

	switch (prop_id) {
		case PROP_ID:
			g_value_set_string(value, priv->id);
			break;
		case PROP_NAME:
			g_value_set_string(value, priv->name);
			break;
		case PROP_TYPE:
			g_value_set_flags(value, priv->type);
			break;
		case PROP_CREATE_CB:
			g_value_set_pointer(value, priv->create);
			break;
		default:
			G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
			break;
	}
}

static void
purple_media_element_info_class_init(PurpleMediaElementInfoClass *klass)
{
	GObjectClass *gobject_class = (GObjectClass*)klass;

	gobject_class->finalize = purple_media_element_info_finalize;
	gobject_class->set_property = purple_media_element_info_set_property;
	gobject_class->get_property = purple_media_element_info_get_property;

	g_object_class_install_property(gobject_class, PROP_ID,
			g_param_spec_string("id",
			"ID",
			"The unique identifier of the element.",
			NULL,
			G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE |
			G_PARAM_STATIC_STRINGS));

	g_object_class_install_property(gobject_class, PROP_NAME,
			g_param_spec_string("name",
			"Name",
			"The friendly/display name of this element.",
			NULL,
			G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE |
			G_PARAM_STATIC_STRINGS));

	g_object_class_install_property(gobject_class, PROP_TYPE,
			g_param_spec_flags("type",
			"Element Type",
			"The type of element this is.",
			PURPLE_TYPE_MEDIA_ELEMENT_TYPE,
			PURPLE_MEDIA_ELEMENT_NONE,
			G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE |
			G_PARAM_STATIC_STRINGS));

	g_object_class_install_property(gobject_class, PROP_CREATE_CB,
			g_param_spec_pointer("create-cb",
			"Create Callback",
			"The function called to create this element.",
			G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE |
			G_PARAM_STATIC_STRINGS));
}

gchar *
purple_media_element_info_get_id(PurpleMediaElementInfo *info)
{
	gchar *id;

	g_return_val_if_fail(PURPLE_IS_MEDIA_ELEMENT_INFO(info), NULL);
	g_object_get(info, "id", &id, NULL);
	return id;
}

gchar *
purple_media_element_info_get_name(PurpleMediaElementInfo *info)
{
	gchar *name;
	g_return_val_if_fail(PURPLE_IS_MEDIA_ELEMENT_INFO(info), NULL);
	g_object_get(info, "name", &name, NULL);
	return name;
}

PurpleMediaElementType
purple_media_element_info_get_element_type(PurpleMediaElementInfo *info)
{
	PurpleMediaElementType type;
	g_return_val_if_fail(PURPLE_IS_MEDIA_ELEMENT_INFO(info),
			PURPLE_MEDIA_ELEMENT_NONE);
	g_object_get(info, "type", &type, NULL);
	return type;
}

GstElement *
purple_media_element_info_call_create(PurpleMediaElementInfo *info,
		PurpleMedia *media, const gchar *session_id,
		const gchar *participant)
{
	PurpleMediaElementCreateCallback create;
	g_return_val_if_fail(PURPLE_IS_MEDIA_ELEMENT_INFO(info), NULL);
	g_object_get(info, "create-cb", &create, NULL);
	if (create) {
		return create(info, media, session_id, participant);
	}
	return NULL;
}