examples: add a simple audio session management example

tests/examples/audiotestsrc-play.c

+/* WirePlumber
+ *
+ * Copyright © 2020 Collabora Ltd.
+ *    @author George Kiagiadakis <george.kiagiadakis@collabora.com>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+/*
+ * This is a very simplistic session manager example that also runs an internal
+ * PipeWire server for ease of use. The PipeWire server runs in its own thread
+ * and our main thread's WpCore (the AppData.core) connects to it through
+ * a socket, as if the PipeWire server was in a different process.
+ *
+ * This example starts 2 media nodes in the media graph: audiotestsrc & alsasink
+ * Then, the session management part constructs endpoints for these nodes
+ * and links them by creating an endpoint link.
+ */
+
+#include <wp/wp.h>
+#include <glib-unix.h>
+#include "../common/test-server.h"
+
+#define APP_ERROR_DOMAIN (app_error_domain_quark ())
+G_DEFINE_QUARK (app-error, app_error_domain)
+
+typedef struct {
+  /* our internal test PipeWire server */
+  WpTestServer server;
+
+  /* cmdline arguments */
+  const gchar *alsa_device;
+
+  /* our main loop and core */
+  GMainContext *context;
+  GMainLoop *loop;
+  WpCore *core;
+  WpSession *session;
+
+  /* nodes provider data */
+  WpNode *audiotestsrc;
+  WpNode *alsasink;
+
+  /* endpoints provider data */
+  WpObjectManager *nodes_om;
+  GPtrArray *session_items;
+
+  /* policy manager data */
+  GSource *interrupt_source;
+
+} AppData;
+
+/*
+ * policy manager: link endpoints together
+ */
+
+static void
+on_endpoints_changed (WpSession * session, AppData * d)
+{
+  g_autoptr (WpEndpoint) src = NULL;
+  g_autoptr (WpEndpoint) sink = NULL;
+
+  g_print ("Endpoints changed, n_endpoints=%u\n",
+      wp_session_get_n_endpoints (session));
+
+  /* a very simplistic lookup, since we don't expect any other endpoints
+     to show up here, but this is the general idea...
+     match endpoints, create links, cache the state and move forward */
+  src = wp_session_lookup_endpoint (session,
+      WP_CONSTRAINT_TYPE_PW_PROPERTY, "media.class", "=s", "Audio/Source", NULL);
+  sink = wp_session_lookup_endpoint (session,
+      WP_CONSTRAINT_TYPE_PW_PROPERTY, "media.class", "=s", "Audio/Sink", NULL);
+
+  if (src) {
+    g_print ("Got endpoint src: %s (%u streams)\n",
+      wp_endpoint_get_name (src),
+      wp_endpoint_get_n_streams (src));
+  }
+  if (sink) {
+    g_print ("Got endpoint sink: %s (%u streams)\n",
+      wp_endpoint_get_name (sink),
+      wp_endpoint_get_n_streams (sink));
+  }
+
+  if (src && sink) {
+    g_autoptr (WpProperties) props = NULL;
+    g_autofree gchar * id =
+        g_strdup_printf ("%u", wp_proxy_get_bound_id (WP_PROXY (sink)));
+
+    /* only the peer endpoint id is required when linking the default streams;
+       everything else will be discovered */
+    props = wp_properties_new ("endpoint-link.input.endpoint", id, NULL);
+    wp_endpoint_create_link (src, props);
+  }
+}
+
+static void
+on_links_changed (WpSession * session, AppData * d)
+{
+  guint n_links = wp_session_get_n_links (session);
+
+  /* activate the link - when endpoint links are created,
+     they don't do anything unless they are activated first */
+  if (n_links == 1) {
+    /* lookup with no constraints will just return the first available object */
+    g_autoptr (WpEndpointLink) link = wp_session_lookup_link (session, NULL);
+
+    g_print ("Requesting link activation...\n");
+    wp_endpoint_link_request_state (link, WP_ENDPOINT_LINK_STATE_ACTIVE);
+  }
+  else if (n_links == 0) {
+    g_print ("Last endpoint link was destroyed; exiting...\n");
+    g_main_loop_quit (d->loop);
+  }
+}
+
+static gboolean
+on_interrupted (AppData * d)
+{
+  g_print ("interrupted; let's try to destroy the link...\n");
+
+  g_autoptr (WpEndpointLink) link = wp_session_lookup_link (d->session, NULL);
+  if (link)
+    wp_proxy_request_destroy (WP_PROXY (link));
+
+  /* remove the interrupt handler so that we can actually
+     interrupt if things get stuck */
+  g_clear_pointer (&d->interrupt_source, g_source_unref);
+  return G_SOURCE_REMOVE;
+}
+
+static void
+start_policy_manager (AppData * d)
+{
+  /* reuse the session pointer that we already have in AppData;
+     under other circumstances, we would retrieve the session
+     with a WpObjectManager */
+  g_signal_connect (d->session, "endpoints-changed",
+      G_CALLBACK (on_endpoints_changed), d);
+  g_signal_connect (d->session, "links-changed",
+      G_CALLBACK (on_links_changed), d);
+
+  d->interrupt_source = g_unix_signal_source_new (SIGINT);
+  g_source_set_callback (d->interrupt_source,
+      G_SOURCE_FUNC (on_interrupted), d, NULL);
+  g_source_attach (d->interrupt_source, d->context);
+}
+
+/*
+ * endpoints provider: creates endpoints for the discovered nodes
+ */
+
+static void
+on_si_exported (WpSessionItem * item, GAsyncResult * res, AppData * d)
+{
+  g_autoptr (GError) error = NULL;
+
+  if (!wp_session_item_export_finish (item, res, &error)) {
+    g_printerr ("Failed to export session item: %s\n", error->message);
+    g_main_loop_quit (d->loop);
+    return;
+  }
+
+  g_print ("Item " WP_OBJECT_FORMAT " exported\n", WP_OBJECT_ARGS (item));
+}
+
+static void
+on_si_activated (WpSessionItem * item, GAsyncResult * res, AppData * d)
+{
+  g_autoptr (GError) error = NULL;
+
+  if (!wp_session_item_activate_finish (item, res, &error)) {
+    g_printerr ("Failed to activate session item: %s\n", error->message);
+    g_main_loop_quit (d->loop);
+    return;
+  }
+
+  g_print ("Item " WP_OBJECT_FORMAT " activated, exporting\n",
+      WP_OBJECT_ARGS (item));
+
+  wp_session_item_export (item, d->session,
+      (GAsyncReadyCallback) on_si_exported, d);
+}
+
+static void
+on_node_added (WpObjectManager * om, WpNode *node, AppData * d)
+{
+  g_autoptr (WpSessionItem) item = NULL;
+  g_auto (GVariantBuilder) b = G_VARIANT_BUILDER_INIT (G_VARIANT_TYPE_VARDICT);
+
+  g_print ("Node " WP_OBJECT_FORMAT " added, creating session item\n",
+      WP_OBJECT_ARGS (node));
+
+  /* load the "si-adapter" Session Item */
+  item = wp_session_item_make (d->core, "si-adapter");
+
+  /* and configure it */
+  g_variant_builder_add (&b, "{sv}", "node",
+      g_variant_new_uint64 ((guint64) node));
+  g_variant_builder_add (&b, "{sv}", "preferred-n-channels",
+      g_variant_new_uint32 (2));
+  if (!wp_session_item_configure (item, g_variant_builder_end (&b))) {
+    g_printerr ("Failed to configure session item\n");
+    g_main_loop_quit (d->loop);
+    return;
+  }
+
+  wp_session_item_activate (item, (GAsyncReadyCallback) on_si_activated, d);
+  g_ptr_array_add (d->session_items, g_steal_pointer (&item));
+}
+
+static void
+start_endpoints_provider (AppData * d)
+{
+  g_print ("Installing watch for nodes...\n");
+
+  /* register a WpObjectManager to listen for available nodes */
+  /* for example purposes, we pretend we don't have access to the data set by
+     start_nodes_provider(), i.e. d->audiotestsrc & d->alsasink */
+  d->nodes_om = wp_object_manager_new ();
+  wp_object_manager_add_interest_1 (d->nodes_om, WP_TYPE_NODE, NULL);
+  wp_object_manager_request_proxy_features (d->nodes_om, WP_TYPE_NODE,
+      WP_PROXY_FEATURES_STANDARD);
+
+  d->session_items = g_ptr_array_new_with_free_func (g_object_unref);
+
+  /* the object manager will emit 'object-added' for every node that is
+     made available, once the node has all the features we requested above */
+  g_signal_connect (d->nodes_om, "object-added", G_CALLBACK (on_node_added), d);
+  wp_core_install_object_manager (d->core, d->nodes_om);
+}
+
+/*
+ * nodes provider: creates the nodes
+ */
+
+static void
+on_node_ready (WpProxy * node, GAsyncResult * res, AppData * d)
+{
+  g_autoptr (GError) error = NULL;
+
+  if (!wp_proxy_augment_finish (node, res, &error)) {
+    g_printerr ("Failed to prepare node: %s\n", error->message);
+    g_main_loop_quit (d->loop);
+    return;
+  }
+
+  g_print ("Node " WP_OBJECT_FORMAT " is ready\n", WP_OBJECT_ARGS (node));
+}
+
+static void
+start_nodes_provider (AppData * d)
+{
+  g_print ("Creating nodes...\n");
+
+  d->audiotestsrc = wp_node_new_from_factory (d->core,
+      "adapter", /* the pipewire factory name */
+      wp_properties_new (
+          /* the spa factory name */
+          "factory.name", "audiotestsrc",
+          /* a friendly name for our node */
+          "node.name", "audiotestsrc",
+          NULL));
+  g_assert (d->audiotestsrc);
+  wp_proxy_augment (WP_PROXY (d->audiotestsrc), WP_PROXY_FEATURES_STANDARD, NULL,
+      (GAsyncReadyCallback) on_node_ready, d);
+
+  d->alsasink = wp_node_new_from_factory (d->core,
+      "adapter", /* the pipewire factory name */
+      wp_properties_new (
+          /* the spa factory name */
+          "factory.name", "api.alsa.pcm.sink",
+          /* a friendly name for our node */
+          "node.name", "alsasink",
+          /* set the device handle (ex. hw:0,0) on the sink */
+          "api.alsa.path", d->alsa_device,
+          NULL));
+  g_assert (d->alsasink);
+  wp_proxy_augment (WP_PROXY (d->alsasink), WP_PROXY_FEATURES_STANDARD, NULL,
+      (GAsyncReadyCallback) on_node_ready, d);
+}
+
+/*
+ * main application: loads modules and the session
+ */
+
+static void
+on_session_ready (WpProxy * session, GAsyncResult * res, AppData * d)
+{
+  g_autoptr (GError) error = NULL;
+
+  if (!wp_proxy_augment_finish (session, res, &error)) {
+    g_printerr ("Failed to prepare session: %s\n", error->message);
+    g_main_loop_quit (d->loop);
+    return;
+  }
+
+  g_print ("Session is ready, starting components...\n");
+
+  start_nodes_provider (d);
+  start_endpoints_provider (d);
+  start_policy_manager (d);
+}
+
+static gboolean
+appdata_init (AppData * d, GError ** error)
+{
+  WpModule *module;
+  WpImplSession *session;
+
+  /* setup the internal test PipeWire server */
+  wp_test_server_setup (&d->server);
+  {
+    /* load server modules (pipewire.conf) */
+    g_autoptr (WpTestServerLocker) lock =
+        wp_test_server_locker_new (&d->server);
+
+    pw_context_add_spa_lib (d->server.context,
+        "audiotestsrc", "audiotestsrc/libspa-audiotestsrc");
+    pw_context_add_spa_lib (d->server.context,
+        "api.alsa.*", "alsa/libspa-alsa");
+
+    if (!pw_context_load_module (d->server.context,
+            "libpipewire-module-spa-node-factory", NULL, NULL)) {
+        g_set_error (error, APP_ERROR_DOMAIN, 0,
+            "Failed to load libpipewire-module-spa-node-factory");
+        return FALSE;
+    }
+    if (!pw_context_load_module (d->server.context,
+            "libpipewire-module-link-factory", NULL, NULL)) {
+        g_set_error (error, APP_ERROR_DOMAIN, 0,
+            "Failed to load libpipewire-module-link-factory");
+        return FALSE;
+    }
+    /* adapter is loaded by pw_context */
+  }
+
+  /* init our main loop */
+  d->context = g_main_context_new ();
+  d->loop = g_main_loop_new (d->context, FALSE);
+
+  /* push the context as the thread default for GTask to work with it,
+     otherwise it will try to use the "default" main context, which we are
+     not using in our main loop, for demonstration purposes */
+  g_main_context_push_thread_default (d->context);
+
+  /* init our core; the "remote.name" key tells it to connect to our
+     test server instead of the default "pipewire-0" */
+  d->core = wp_core_new (d->context, wp_properties_new (
+          "remote.name", d->server.name,
+          NULL));
+
+  /* load wireplumber modules (wireplumber.conf) */
+  if (!(module = wp_module_load (d->core, "C",
+          "libwireplumber-module-si-simple-node-endpoint", NULL, error)))
+    return FALSE;
+
+  if (!(module = wp_module_load (d->core, "C",
+          "libwireplumber-module-si-audio-softdsp-endpoint", NULL, error)))
+    return FALSE;
+
+  if (!(module = wp_module_load (d->core, "C",
+          "libwireplumber-module-si-adapter", NULL, error)))
+    return FALSE;
+
+  if (!(module = wp_module_load (d->core, "C",
+          "libwireplumber-module-si-convert", NULL, error)))
+    return FALSE;
+
+  if (!(module = wp_module_load (d->core, "C",
+          "libwireplumber-module-si-standard-link", NULL, error)))
+    return FALSE;
+
+  /* connect */
+  if (!wp_core_connect (d->core)) {
+    g_set_error (error, APP_ERROR_DOMAIN, 0,
+        "Failed to connect to the test server");
+    return FALSE;
+  }
+
+  g_print ("Creating session...\n");
+
+  /* create a session */
+  d->session = WP_SESSION (session = wp_impl_session_new (d->core));
+  wp_impl_session_set_property (session, "session.name", "audio");
+  wp_proxy_augment (WP_PROXY (session), WP_SESSION_FEATURES_STANDARD, NULL,
+      (GAsyncReadyCallback) on_session_ready, d);
+  return TRUE;
+}
+
+static void
+appdata_clear (AppData * d)
+{
+  /* policy manager data */
+  g_clear_pointer (&d->interrupt_source, g_source_unref);
+
+  /* endpoints provider data */
+  g_clear_pointer (&d->session_items, g_ptr_array_unref);
+  g_clear_object (&d->nodes_om);
+
+  /* nodes provider data */
+  g_clear_object (&d->audiotestsrc);
+  g_clear_object (&d->alsasink);
+
+  /* main app data */
+  g_clear_object (&d->session);
+  g_clear_object (&d->core);
+  g_clear_pointer (&d->loop, g_main_loop_unref);
+  g_clear_pointer (&d->context, g_main_context_unref);
+  wp_test_server_teardown (&d->server);
+}
+
+G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC (AppData, appdata_clear)
+
+gint
+main (gint argc, gchar *argv[])
+{
+  g_auto (AppData) data = {0};
+  g_autoptr (GError) error = NULL;
+
+  pw_init (NULL, NULL);
+  g_log_set_writer_func (wp_log_writer_default, NULL, NULL);
+
+  if (argc > 1)
+    data.alsa_device = argv[1];
+  else
+    data.alsa_device = "hw:0,0";
+
+  if (!appdata_init (&data, &error)) {
+    g_printerr ("Initialization failed:\n  %s\n", error->message);
+    return 1;
+  }
+
+  g_main_loop_run (data.loop);
+  return 0;
+}

tests/examples/meson.build

+executable('audiotestsrc-play',
+  'audiotestsrc-play.c',
+  c_args : [
+    '-D_GNU_SOURCE',
+    '-DG_LOG_USE_STRUCTURED',
+    '-DG_LOG_DOMAIN="audiotestsrc-play"',
+  ],
+  install: false,
+  dependencies : [giounix_dep, wp_dep, pipewire_dep],
+)

tests/meson.build

-subdir('modules')
 subdir('wp')
 subdir('wptoml')
+subdir('modules')
+subdir('examples')