Add more generic export-spa example

Replace the v4l2 example with a more generic version that can add
any spa node to a remote graph
Make the dictionary items const
Add some info to nodes and factories. Add the node info to the node
properties. We can then set the media.class directly on the node,
instead of letting the monitor set it.
Debug node info in spa-inspect.
Do async operation on the audiotestsrc and videotestsrc differently.

src/examples/export-source.c

@@ -29,8 +29,6 @@
 #include <spa/lib/debug.h>
 
 #include <pipewire/pipewire.h>
-#include <pipewire/module.h>
-#include <pipewire/node-factory.h>
 
 #define M_PI_M2 ( M_PI + M_PI )
 
@@ -312,9 +310,6 @@ static int impl_node_process_output(struct spa_node *node)
 	int16_t *dst;
         struct spa_port_io *io = d->io;
 
-	if (io->status == SPA_RESULT_HAVE_BUFFER)
-		return SPA_RESULT_HAVE_BUFFER;
-
 	if (io->buffer_id < d->n_buffers) {
 		reuse_buffer(d, io->buffer_id);
 		io->buffer_id = SPA_ID_INVALID;

src/examples/export-spa.c

@@ -29,7 +29,6 @@
 #include <spa/lib/debug.h>
 
 #include <pipewire/pipewire.h>
-#include <pipewire/module.h>
 #include <pipewire/node-factory.h>
 
 struct data {
@@ -42,19 +41,33 @@ struct data {
 	struct spa_hook remote_listener;
 
 	struct pw_node *node;
+	const char *library;
+	const char *factory;
+	const char *path;
 };
 
-static void make_node(struct data *data)
+static int make_node(struct data *data)
 {
 	struct pw_node_factory *factory;
 	struct pw_properties *props;
 
         factory = pw_core_find_node_factory(data->core, "spa-node-factory");
-        props = pw_properties_new("spa.library.name", "v4l2/libspa-v4l2",
-                                  "spa.factory.name", "v4l2-source", NULL);
-        data->node = pw_node_factory_create_node(factory, NULL, "v4l2-source", props);
+	if (factory == NULL)
+		return -1;
+
+        props = pw_properties_new("spa.library.name", data->library,
+                                  "spa.factory.name", data->factory, NULL);
+
+	if (data->path) {
+		pw_properties_set(props, "pipewire.autoconnect", "1");
+		pw_properties_set(props, "pipewire.target.node", data->path);
+	}
+
+        data->node = pw_node_factory_create_node(factory, NULL, data->factory, props);
 
 	pw_remote_export(data->remote, data->node);
+
+	return 0;
 }
 
 static void on_state_changed(void *_data, enum pw_remote_state old, enum pw_remote_state state, const char *error)
@@ -69,7 +82,10 @@ static void on_state_changed(void *_data, enum pw_remote_state old, enum pw_remo
 
 	case PW_REMOTE_STATE_CONNECTED:
 		printf("remote state: \"%s\"\n", pw_remote_state_as_string(state));
-		make_node(data);
+		if (make_node(data) < 0) {
+			pw_log_error("can't make node");
+			pw_main_loop_quit(data->loop);
+		}
 		break;
 
 	default:
@@ -96,6 +112,13 @@ int main(int argc, char *argv[])
 
 	pw_init(&argc, &argv);
 
+	if (argc < 3) {
+		fprintf(stderr, "usage: %s <library> <factory> [path]\n\n"
+				"\texample: %s v4l2/libspa-v4l2 v4l2-source\n\n",
+				argv[0], argv[0]);
+		return -1;
+	}
+
 	data.loop = pw_main_loop_new(NULL);
 	l = pw_main_loop_get_loop(data.loop);
         pw_loop_add_signal(l, SIGINT, do_quit, &data);
@@ -103,6 +126,10 @@ int main(int argc, char *argv[])
 	data.core = pw_core_new(l, NULL);
 	data.t = pw_core_get_type(data.core);
         data.remote = pw_remote_new(data.core, NULL);
+	data.library = argv[1];
+	data.factory = argv[2];
+	if (argc > 3)
+		data.path = argv[3];
 
 	pw_module_load(data.core, "libpipewire-module-spa-node-factory", NULL);
 
@@ -114,7 +141,6 @@ int main(int argc, char *argv[])
 
 	pw_main_loop_run(data.loop);
 
-	pw_remote_destroy(data.remote);
 	if (data.node)
 		pw_node_destroy(data.node);
 	pw_core_destroy(data.core);

src/examples/meson.build

@@ -3,17 +3,18 @@ executable('video-src',
   install: false,
   dependencies : [pipewire_dep],
 )
-executable('export-v4l2',
-  'export-v4l2.c',
-  install: false,
-  dependencies : [pipewire_dep],
-)
 executable('export-source',
   'export-source.c',
   install: false,
   dependencies : [pipewire_dep, libm],
 )
 
+executable('export-spa',
+  'export-spa.c',
+  install: false,
+  dependencies : [pipewire_dep, libm],
+)
+
 if sdl_dep.found()
   executable('video-play',
     'video-play.c',