module-pulse-tunner: add module to tunnel to PulseAudio

Add a module that can make a source or sink that tunnels audio
to or from a (remote) PulseAudio server.

meson.build

@@ -310,6 +310,7 @@ dbus_dep = dependency('dbus-1')
 sdl_dep = dependency('sdl2', required : get_option('sdl2'))
 ncurses_dep = dependency('ncursesw', required : false)
 sndfile_dep = dependency('sndfile', version : '>= 1.0.20', required : get_option('sndfile'))
+pulseaudio_dep = dependency('libpulse', required : get_option('libpulse'))
 
 gst_option = get_option('gstreamer')
 gst_deps_def = {

meson_options.txt

@@ -183,3 +183,7 @@ option('sndfile',
        description: 'Enable code that depends on libsndfile',
        type: 'feature',
        value: 'auto')
+option('libpulse',
+       description: 'Enable code that depends on libpulse',
+       type: 'feature',
+       value: 'auto')

src/modules/meson.build

@@ -149,6 +149,18 @@ pipewire_module_protocol_pulse = shared_library('pipewire-module-protocol-pulse'
   dependencies : pipewire_module_protocol_pulse_deps,
 )
 
+if pulseaudio_dep.found()
+  pipewire_module_pulse_tunnel = shared_library('pipewire-module-pulse-tunnel',
+  [ 'module-pulse-tunnel.c' ],
+  c_args : pipewire_module_c_args,
+  include_directories : [configinc, spa_inc],
+  install : true,
+  install_dir : modules_install_dir,
+  install_rpath: modules_install_dir,
+  dependencies : [mathlib, dl_lib, pipewire_dep, pulseaudio_dep],
+)
+endif
+
 pipewire_module_protocol_simple = shared_library('pipewire-module-protocol-simple',
   [ 'module-protocol-simple.c' ],
   c_args : pipewire_module_c_args,

src/modules/module-pulse-tunnel.c

@@ -0,0 +1,794 @@
+/* PipeWire
+ *
+ * Copyright © 2021 Wim Taymans
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <limits.h>
+#include <math.h>
+
+#include "config.h"
+
+#include <spa/utils/result.h>
+#include <spa/utils/json.h>
+#include <spa/utils/ringbuffer.h>
+#include <spa/debug/pod.h>
+#include <spa/pod/builder.h>
+#include <spa/param/audio/format-utils.h>
+#include <spa/param/audio/raw.h>
+
+#include <pipewire/impl.h>
+
+#include <pulse/pulseaudio.h>
+
+#define NAME "pulse-tunnel"
+
+#define MODULE_USAGE	"[ remote.name=<remote> ] "				\
+			"[ node.latency=<latency as fraction> ] "		\
+			"[ node.name=<name of the nodes> ] "			\
+			"[ node.description=<description of the nodes> ] "	\
+			"[ audio.rate=<sample rate> ] "				\
+			"[ audio.channels=<number of channels> ] "		\
+			"[ audio.position=<channel map> ] "			\
+			"pulse.server.address=<address> "			\
+			"[ tunnel.mode=capture|playback "			\
+			"[ stream.props=<properties> ] "
+
+
+static const struct spa_dict_item module_props[] = {
+	{ PW_KEY_MODULE_AUTHOR, "Wim Taymans <wim.taymans@gmail.com>" },
+	{ PW_KEY_MODULE_DESCRIPTION, "Create a PulseAudio tunnel" },
+	{ PW_KEY_MODULE_USAGE, MODULE_USAGE },
+	{ PW_KEY_MODULE_VERSION, PACKAGE_VERSION },
+};
+
+#define RINGBUFFER_SIZE		(1u << 22)
+#define RINGBUFFER_MASK		(RINGBUFFER_SIZE-1)
+
+struct impl {
+	struct pw_context *context;
+
+#define MODE_PLAYBACK	0
+#define MODE_CAPTURE	1
+	uint32_t mode;
+	struct pw_properties *props;
+
+	struct pw_impl_module *module;
+	struct pw_work_queue *work;
+
+	struct spa_hook module_listener;
+
+	struct pw_core *core;
+	struct spa_hook core_proxy_listener;
+	struct spa_hook core_listener;
+
+	struct pw_properties *stream_props;
+	struct pw_stream *stream;
+	struct spa_hook stream_listener;
+	struct spa_io_rate_match *rate_match;
+	struct spa_audio_info_raw info;
+	uint32_t frame_size;
+
+	struct spa_ringbuffer ring;
+	void *buffer;
+	uint8_t empty[8192];
+
+	pa_threaded_mainloop *pa_mainloop;
+	pa_context *pa_context;
+	pa_stream *pa_stream;
+
+	unsigned int do_disconnect:1;
+	unsigned int unloading:1;
+};
+
+static void do_unload_module(void *obj, void *data, int res, uint32_t id)
+{
+	struct impl *impl = data;
+	pw_impl_module_destroy(impl->module);
+}
+
+static void unload_module(struct impl *impl)
+{
+	if (!impl->unloading) {
+		impl->unloading = true;
+		pw_work_queue_add(impl->work, impl, 0, do_unload_module, impl);
+	}
+}
+
+static void cork_stream(struct impl *impl, bool cork)
+{
+	pa_operation *operation;
+
+	pa_threaded_mainloop_lock(impl->pa_mainloop);
+
+	pw_log_info("corking: %d", cork);
+	if (cork && impl->mode == MODE_PLAYBACK) {
+		/* When the sink becomes suspended (which is the only case where we
+		 * cork the stream), we don't want to keep any old data around, because
+		 * the old data is most likely unrelated to the audio that will be
+		 * played at the time when the sink starts running again. */
+		if ((operation = pa_stream_flush(impl->pa_stream, NULL, NULL)))
+			pa_operation_unref(operation);
+		spa_ringbuffer_init(&impl->ring);
+	}
+	if ((operation = pa_stream_cork(impl->pa_stream, cork, NULL, NULL)))
+		pa_operation_unref(operation);
+
+	pa_threaded_mainloop_unlock(impl->pa_mainloop);
+}
+
+static void stream_destroy(void *d)
+{
+	struct impl *impl = d;
+	spa_hook_remove(&impl->stream_listener);
+	impl->stream = NULL;
+}
+
+static void stream_state_changed(void *d, enum pw_stream_state old,
+		enum pw_stream_state state, const char *error)
+{
+	struct impl *impl = d;
+	switch (state) {
+	case PW_STREAM_STATE_ERROR:
+	case PW_STREAM_STATE_UNCONNECTED:
+		unload_module(impl);
+		break;
+	case PW_STREAM_STATE_PAUSED:
+		cork_stream(impl, true);
+		break;
+	case PW_STREAM_STATE_STREAMING:
+		cork_stream(impl, false);
+		break;
+	default:
+		break;
+	}
+}
+
+static void playback_stream_process(void *d)
+{
+	struct impl *impl = d;
+	struct pw_buffer *buf;
+	struct spa_data *bd;
+	int32_t filled;
+	uint32_t write_index, size;
+
+	if ((buf = pw_stream_dequeue_buffer(impl->stream)) == NULL) {
+		pw_log_warn("out of buffers: %m");
+		return;
+	}
+
+	bd = &buf->buffer->datas[0];
+	size = SPA_MIN(bd->chunk->size, RINGBUFFER_SIZE);
+
+	filled = spa_ringbuffer_get_write_index(&impl->ring, &write_index);
+	if (filled < 0) {
+		pw_log_warn(NAME" %p: underrun write:%u filled:%d",
+				impl, write_index, filled);
+	} else if ((uint32_t)filled + size > RINGBUFFER_SIZE) {
+		pw_log_debug(NAME" %p: overrun write:%u filled:%d size:%u max:%u",
+                                        impl, write_index, filled,
+                                        size, RINGBUFFER_SIZE);
+	}
+	spa_ringbuffer_write_data(&impl->ring,
+				impl->buffer, RINGBUFFER_SIZE,
+                                write_index & RINGBUFFER_MASK,
+                                SPA_PTROFF(bd->data, bd->chunk->offset, void),
+				size);
+	write_index += size;
+	spa_ringbuffer_write_update(&impl->ring, write_index);
+
+	pw_stream_queue_buffer(impl->stream, buf);
+}
+
+static void capture_stream_process(void *d)
+{
+	struct impl *impl = d;
+	struct pw_buffer *buf;
+	struct spa_data *bd;
+	int32_t avail;
+	uint32_t size, req, read_index;
+
+	if ((buf = pw_stream_dequeue_buffer(impl->stream)) == NULL) {
+		pw_log_warn("out of buffers: %m");
+		return;
+	}
+
+	bd = &buf->buffer->datas[0];
+
+	if (impl->rate_match)
+		req = impl->rate_match->size * impl->frame_size;
+	else
+		req = 4096;
+
+	avail = spa_ringbuffer_get_read_index(&impl->ring, &read_index);
+	if (avail <= 0) {
+		size = SPA_MIN(bd->maxsize, req);
+		memset(bd->data, 0, size);
+	} else {
+		size = SPA_MIN(bd->maxsize, (uint32_t)avail);
+		size = SPA_MIN(bd->maxsize, req);
+
+		spa_ringbuffer_read_data(&impl->ring,
+				impl->buffer, RINGBUFFER_SIZE,
+				read_index & RINGBUFFER_MASK,
+				bd->data, size);
+
+		read_index += size;
+		spa_ringbuffer_read_update(&impl->ring, read_index);
+	}
+	bd->chunk->offset = 0;
+	bd->chunk->size = size;
+
+	pw_stream_queue_buffer(impl->stream, buf);
+}
+
+static void stream_io_changed(void *data, uint32_t id, void *area, uint32_t size)
+{
+	struct impl *impl = data;
+	switch (id) {
+	case SPA_IO_RateMatch:
+		impl->rate_match = area;
+		break;
+	}
+}
+
+static const struct pw_stream_events playback_stream_events = {
+	PW_VERSION_STREAM_EVENTS,
+	.destroy = stream_destroy,
+	.state_changed = stream_state_changed,
+	.process = playback_stream_process
+};
+
+static const struct pw_stream_events capture_stream_events = {
+	PW_VERSION_STREAM_EVENTS,
+	.destroy = stream_destroy,
+	.state_changed = stream_state_changed,
+	.io_changed = stream_io_changed,
+	.process = capture_stream_process
+};
+
+static int create_stream(struct impl *impl)
+{
+	int res;
+	uint32_t n_params;
+	const struct spa_pod *params[1];
+	uint8_t buffer[1024];
+	struct spa_pod_builder b;
+
+
+	impl->stream = pw_stream_new(impl->core, "pulse", impl->stream_props);
+	impl->stream_props = NULL;
+
+	if (impl->stream == NULL)
+		return -errno;
+
+	if (impl->mode == MODE_CAPTURE) {
+		pw_stream_add_listener(impl->stream,
+				&impl->stream_listener,
+				&capture_stream_events, impl);
+	} else {
+		pw_stream_add_listener(impl->stream,
+				&impl->stream_listener,
+				&playback_stream_events, impl);
+	}
+
+	impl->info = SPA_AUDIO_INFO_RAW_INIT(
+			.format = SPA_AUDIO_FORMAT_S16,
+			.rate = 48000,
+			.channels = 2,
+			.position = { SPA_AUDIO_CHANNEL_FL, SPA_AUDIO_CHANNEL_FR });
+	impl->frame_size = 2 * 2;
+
+	n_params = 0;
+	spa_pod_builder_init(&b, buffer, sizeof(buffer));
+	params[n_params++] = spa_format_audio_raw_build(&b,
+			SPA_PARAM_EnumFormat, &impl->info);
+
+	if ((res = pw_stream_connect(impl->stream,
+			impl->mode == MODE_CAPTURE ? PW_DIRECTION_OUTPUT : PW_DIRECTION_INPUT,
+			PW_ID_ANY,
+			PW_STREAM_FLAG_AUTOCONNECT |
+			PW_STREAM_FLAG_MAP_BUFFERS,
+			params, n_params)) < 0)
+		return res;
+
+	return 0;
+}
+
+static void context_state_cb(pa_context *c, void *userdata)
+{
+	struct impl *impl = userdata;
+	switch (pa_context_get_state(c)) {
+	case PA_CONTEXT_READY:
+	case PA_CONTEXT_TERMINATED:
+	case PA_CONTEXT_FAILED:
+		pa_threaded_mainloop_signal(impl->pa_mainloop, 0);
+		break;
+	case PA_CONTEXT_UNCONNECTED:
+	case PA_CONTEXT_CONNECTING:
+	case PA_CONTEXT_AUTHORIZING:
+	case PA_CONTEXT_SETTING_NAME:
+		break;
+	}
+}
+
+static void stream_state_cb(pa_stream *s, void * userdata)
+{
+	struct impl *impl = userdata;
+	switch (pa_stream_get_state(s)) {
+	case PA_STREAM_READY:
+	case PA_STREAM_FAILED:
+	case PA_STREAM_TERMINATED:
+		pa_threaded_mainloop_signal(impl->pa_mainloop, 0);
+		break;
+	case PA_STREAM_UNCONNECTED:
+	case PA_STREAM_CREATING:
+		break;
+	}
+}
+
+static void stream_read_request_cb(pa_stream *s, size_t length, void *userdata)
+{
+	struct impl *impl = userdata;
+	int32_t filled;
+	uint32_t write_index;
+
+	filled = spa_ringbuffer_get_write_index(&impl->ring, &write_index);
+
+	if (filled < 0) {
+		pw_log_warn(NAME" %p: underrun write:%u filled:%d",
+				impl, write_index, filled);
+	} else if (filled + length > RINGBUFFER_SIZE) {
+		pw_log_warn(NAME" %p: overrun write:%u filled:%d",
+				impl, write_index, filled);
+	}
+	while (length > 0) {
+		const void *p;
+		size_t nbytes = 0;
+
+		if (PA_UNLIKELY(pa_stream_peek(impl->pa_stream, &p, &nbytes) != 0)) {
+			pw_log_error("pa_stream_peek() failed: %s",
+					pa_strerror(pa_context_errno(impl->pa_context)));
+			return;
+		}
+		pw_log_debug("read %zd nbytes:%zd", length, nbytes);
+
+		if (length < nbytes)
+			break;
+
+		spa_ringbuffer_write_data(&impl->ring,
+				impl->buffer, RINGBUFFER_SIZE,
+				write_index & RINGBUFFER_MASK,
+				p, nbytes);
+
+		length -= nbytes;
+		write_index += nbytes;
+		pa_stream_drop(impl->pa_stream);
+	}
+	spa_ringbuffer_write_update(&impl->ring, write_index);
+}
+
+static void stream_write_request_cb(pa_stream *s, size_t length, void *userdata)
+{
+	struct impl *impl = userdata;
+	int32_t avail;
+	uint32_t read_index, len, offset, l0, l1;
+
+	avail = spa_ringbuffer_get_read_index(&impl->ring, &read_index);
+
+	while (avail < (int32_t)length) {
+		/* send silence for the data we don't have */
+		len = SPA_MIN(length - avail, sizeof(impl->empty));
+		pa_stream_write(impl->pa_stream,
+				impl->empty, len,
+				NULL, 0, PA_SEEK_RELATIVE);
+		length -= len;
+	}
+	if (length > 0 && avail >= (int32_t)length) {
+		/* always send as much as is requested */
+		len = length;
+		offset = read_index & RINGBUFFER_MASK;
+		l0 = SPA_MIN(len, RINGBUFFER_SIZE - offset);
+		l1 = len - l0;
+
+		pa_stream_write(impl->pa_stream,
+				SPA_PTROFF(impl->buffer, offset, void), l0,
+				NULL, 0, PA_SEEK_RELATIVE);
+
+		if (SPA_UNLIKELY(l1 > 0)) {
+			pa_stream_write(impl->pa_stream,
+					impl->buffer, l1,
+					NULL, 0, PA_SEEK_RELATIVE);
+		}
+		read_index += len;
+		spa_ringbuffer_read_update(&impl->ring, read_index);
+	}
+}
+
+static void stream_latency_update_cb(pa_stream *s, void *userdata)
+{
+	struct impl *impl = userdata;
+	pa_threaded_mainloop_signal(impl->pa_mainloop, 0);
+}
+
+static pa_proplist* tunnel_new_proplist(struct impl *impl)
+{
+	pa_proplist *proplist = pa_proplist_new();
+	pa_proplist_sets(proplist, PA_PROP_APPLICATION_NAME, "PipeWire");
+	pa_proplist_sets(proplist, PA_PROP_APPLICATION_ID, "org.pipewire.PipeWire");
+	pa_proplist_sets(proplist, PA_PROP_APPLICATION_VERSION, PACKAGE_VERSION);
+	return proplist;
+}
+
+static int create_pulse_stream(struct impl *impl)
+{
+	pa_sample_spec ss;
+	const char *server_address;
+	pa_proplist *props = NULL;
+	pa_mainloop_api *api;
+	int res = -EIO;
+
+	if ((impl->pa_mainloop = pa_threaded_mainloop_new()) == NULL)
+		goto error;
+
+	api = pa_threaded_mainloop_get_api(impl->pa_mainloop);
+
+	props = tunnel_new_proplist(impl);
+	impl->pa_context = pa_context_new_with_proplist(api, "PipeWire", props);
+	pa_proplist_free(props);
+
+	if (impl->pa_context == NULL)
+		goto error;
+
+	pa_context_set_state_callback(impl->pa_context, context_state_cb, impl);
+
+	server_address = pw_properties_get(impl->props, "pulse.server.address");
+
+	if (pa_context_connect(impl->pa_context, server_address, 0, NULL) < 0) {
+		res = pa_context_errno(impl->pa_context);
+		goto error;
+	}
+
+	pa_threaded_mainloop_lock(impl->pa_mainloop);
+
+	if (pa_threaded_mainloop_start(impl->pa_mainloop) < 0)
+		goto error_unlock;
+
+	for (;;) {
+		pa_context_state_t state;
+
+		state = pa_context_get_state(impl->pa_context);
+		if (state == PA_CONTEXT_READY)
+			break;
+
+		if (!PA_CONTEXT_IS_GOOD(state)) {
+			res = pa_context_errno(impl->pa_context);
+			goto error_unlock;
+		}
+		/* Wait until the context is ready */
+		pa_threaded_mainloop_wait(impl->pa_mainloop);
+	}
+
+	ss.format = PA_SAMPLE_S16NE;
+	ss.channels = 2;
+	ss.rate = 48000;
+
+	if (!(impl->pa_stream = pa_stream_new(impl->pa_context, "PipeWire", &ss, NULL))) {
+		res = pa_context_errno(impl->pa_context);
+		goto error_unlock;
+	}
+
+	pa_stream_set_state_callback(impl->pa_stream, stream_state_cb, impl);
+	pa_stream_set_read_callback(impl->pa_stream, stream_read_request_cb, impl);
+	pa_stream_set_write_callback(impl->pa_stream, stream_write_request_cb, impl);
+	pa_stream_set_latency_update_callback(impl->pa_stream, stream_latency_update_cb, impl);
+
+	if (impl->mode == MODE_CAPTURE) {
+		res = pa_stream_connect_record(impl->pa_stream,
+				NULL, NULL,
+				PA_STREAM_INTERPOLATE_TIMING |
+				PA_STREAM_ADJUST_LATENCY |
+				PA_STREAM_AUTO_TIMING_UPDATE);
+	} else {
+		res = pa_stream_connect_playback(impl->pa_stream,
+				NULL, NULL,
+				PA_STREAM_INTERPOLATE_TIMING |
+				PA_STREAM_ADJUST_LATENCY |
+				PA_STREAM_AUTO_TIMING_UPDATE,
+				NULL, NULL);
+	}
+
+	if (res < 0) {
+		res = pa_context_errno(impl->pa_context);
+		goto error_unlock;
+	}
+
+	for (;;) {
+		pa_stream_state_t state;
+
+		state = pa_stream_get_state(impl->pa_stream);
+		if (state == PA_STREAM_READY)
+			break;
+
+		if (!PA_STREAM_IS_GOOD(state)) {
+			res = pa_context_errno(impl->pa_context);
+			goto error_unlock;
+		}
+
+		/* Wait until the stream is ready */
+		pa_threaded_mainloop_wait(impl->pa_mainloop);
+	}
+
+	pa_threaded_mainloop_unlock(impl->pa_mainloop);
+
+	return 0;
+
+error_unlock:
+	pa_threaded_mainloop_unlock(impl->pa_mainloop);
+error:
+	pw_log_error("failed to connect: %s", pa_strerror(res));
+	return -res;
+}
+
+
+static void core_error(void *data, uint32_t id, int seq, int res, const char *message)
+{
+	struct impl *impl = data;
+
+	pw_log_error("error id:%u seq:%d res:%d (%s): %s",
+			id, seq, res, spa_strerror(res), message);
+
+	if (id == PW_ID_CORE && res == -EPIPE)
+		unload_module(impl);
+}
+
+static const struct pw_core_events core_events = {
+	PW_VERSION_CORE_EVENTS,
+	.error = core_error,
+};
+
+static void core_destroy(void *d)
+{
+	struct impl *impl = d;
+	spa_hook_remove(&impl->core_listener);
+	impl->core = NULL;
+	unload_module(impl);
+}
+
+static const struct pw_proxy_events core_proxy_events = {
+	.destroy = core_destroy,
+};
+
+static void impl_destroy(struct impl *impl)
+{
+
+	if (impl->pa_mainloop)
+		pa_threaded_mainloop_stop(impl->pa_mainloop);
+	if (impl->pa_stream)
+		pa_stream_unref(impl->pa_stream);
+	if (impl->pa_context) {
+		pa_context_disconnect(impl->pa_context);
+		pa_context_unref(impl->pa_context);
+	}
+	if (impl->pa_mainloop)
+		pa_threaded_mainloop_free(impl->pa_mainloop);
+
+	if (impl->stream)
+		pw_stream_destroy(impl->stream);
+	if (impl->core && impl->do_disconnect)
+		pw_core_disconnect(impl->core);
+
+	if (impl->stream_props)
+		pw_properties_free(impl->stream_props);
+	if (impl->props)
+		pw_properties_free(impl->props);
+
+	pw_work_queue_cancel(impl->work, impl, SPA_ID_INVALID);
+	free(impl->buffer);
+	free(impl);
+}
+
+static void module_destroy(void *data)
+{
+	struct impl *impl = data;
+	impl->unloading = true;
+	spa_hook_remove(&impl->module_listener);
+	impl_destroy(impl);
+}
+
+static const struct pw_impl_module_events module_events = {
+	PW_VERSION_IMPL_MODULE_EVENTS,
+	.destroy = module_destroy,
+};
+
+static uint32_t channel_from_name(const char *name)
+{
+	int i;
+	for (i = 0; spa_type_audio_channel[i].name; i++) {
+		if (strcmp(name, spa_debug_type_short_name(spa_type_audio_channel[i].name)) == 0)
+			return spa_type_audio_channel[i].type;
+	}
+	return SPA_AUDIO_CHANNEL_UNKNOWN;
+}
+
+static void parse_position(struct spa_audio_info_raw *info, const char *val, size_t len)
+{
+	struct spa_json it[2];
+	char v[256];
+
+	spa_json_init(&it[0], val, len);
+        if (spa_json_enter_array(&it[0], &it[1]) <= 0)
+                spa_json_init(&it[1], val, len);
+
+	info->channels = 0;
+	while (spa_json_get_string(&it[1], v, sizeof(v)) > 0 &&
+	    info->channels < SPA_AUDIO_MAX_CHANNELS) {
+		info->position[info->channels++] = channel_from_name(v);
+	}
+}
+
+static void parse_audio_info(struct pw_properties *props, struct spa_audio_info_raw *info)
+{
+	const char *str;
+
+	*info = SPA_AUDIO_INFO_RAW_INIT(
+			.format = SPA_AUDIO_FORMAT_F32P);
+	if ((str = pw_properties_get(props, PW_KEY_AUDIO_RATE)) != NULL)
+		info->rate = atoi(str);
+	if ((str = pw_properties_get(props, PW_KEY_AUDIO_CHANNELS)) != NULL)
+		info->channels = atoi(str);
+	if ((str = pw_properties_get(props, SPA_KEY_AUDIO_POSITION)) != NULL)
+		parse_position(info, str, strlen(str));
+}
+
+static void copy_props(struct impl *impl, struct pw_properties *props, const char *key)
+{
+	const char *str;
+	if ((str = pw_properties_get(props, key)) != NULL) {
+		if (pw_properties_get(impl->stream_props, key) == NULL)
+			pw_properties_set(impl->stream_props, key, str);
+	}
+}
+
+SPA_EXPORT
+int pipewire__module_init(struct pw_impl_module *module, const char *args)
+{
+	struct pw_context *context = pw_impl_module_get_context(module);
+	struct pw_properties *props = NULL;
+	struct impl *impl;
+	const char *str;
+	int res;
+
+	impl = calloc(1, sizeof(struct impl));
+	if (impl == NULL)
+		return -errno;
+
+	pw_log_debug("module %p: new %s", impl, args);
+
+	if (args == NULL)
+		args = "";
+
+	props = pw_properties_new_string(args);
+	if (props == NULL) {
+		res = -errno;
+		pw_log_error( "can't create properties: %m");
+		goto error;
+	}
+	impl->props = props;
+
+	impl->stream_props = pw_properties_new(NULL, NULL);
+	if (impl->stream_props == NULL) {
+		res = -errno;
+		pw_log_error( "can't create properties: %m");
+		goto error;
+	}
+
+	impl->module = module;
+	impl->context = context;
+	impl->work = pw_context_get_work_queue(context);
+
+	spa_ringbuffer_init(&impl->ring);
+	impl->buffer = calloc(1, RINGBUFFER_SIZE);
+
+	if ((str = pw_properties_get(props, "tunnel.mode")) != NULL) {
+		if (strcmp(str, "capture") == 0) {
+			impl->mode = MODE_CAPTURE;
+		} else if (strcmp(str, "playback") == 0) {
+			impl->mode = MODE_PLAYBACK;
+		} else {
+			pw_log_error("invalid tunnel.mode '%s'", str);
+			res = -EINVAL;
+			goto error;
+		}
+	}
+	if (pw_properties_get(props, PW_KEY_NODE_GROUP) == NULL)
+		pw_properties_set(props, PW_KEY_NODE_GROUP, "pipewire.dummy");
+	if (pw_properties_get(props, PW_KEY_NODE_VIRTUAL) == NULL)
+		pw_properties_set(props, PW_KEY_NODE_VIRTUAL, "true");
+
+	if (pw_properties_get(props, PW_KEY_MEDIA_CLASS) == NULL)
+		pw_properties_set(props, PW_KEY_MEDIA_CLASS,
+				impl->mode == MODE_PLAYBACK ?
+					"Audio/Sink" : "Audio/Source");
+
+	if ((str = pw_properties_get(props, "stream.props")) != NULL)
+		pw_properties_update_string(impl->stream_props, str, strlen(str));
+
+	copy_props(impl, props, PW_KEY_AUDIO_RATE);
+	copy_props(impl, props, PW_KEY_AUDIO_CHANNELS);
+	copy_props(impl, props, SPA_KEY_AUDIO_POSITION);
+	copy_props(impl, props, PW_KEY_NODE_NAME);
+	copy_props(impl, props, PW_KEY_NODE_DESCRIPTION);
+	copy_props(impl, props, PW_KEY_NODE_GROUP);
+	copy_props(impl, props, PW_KEY_NODE_LATENCY);
+	copy_props(impl, props, PW_KEY_NODE_VIRTUAL);
+	copy_props(impl, props, PW_KEY_MEDIA_CLASS);
+
+	parse_audio_info(impl->stream_props, &impl->info);
+
+	impl->core = pw_context_get_object(impl->context, PW_TYPE_INTERFACE_Core);
+	if (impl->core == NULL) {
+		str = pw_properties_get(props, PW_KEY_REMOTE_NAME);
+		impl->core = pw_context_connect(impl->context,
+				pw_properties_new(
+					PW_KEY_REMOTE_NAME, str,
+					NULL),
+				0);
+		impl->do_disconnect = true;
+	}
+	if (impl->core == NULL) {
+		res = -errno;
+		pw_log_error("can't connect: %m");
+		goto error;
+	}
+
+	pw_proxy_add_listener((struct pw_proxy*)impl->core,
+			&impl->core_proxy_listener,
+			&core_proxy_events, impl);
+	pw_core_add_listener(impl->core,
+			&impl->core_listener,
+			&core_events, impl);
+
+	if ((res = create_pulse_stream(impl)) < 0)
+		goto error;
+
+	if ((res = create_stream(impl)) < 0)
+		goto error;
+
+	pw_impl_module_add_listener(module, &impl->module_listener, &module_events, impl);
+
+	pw_impl_module_update_properties(module, &SPA_DICT_INIT_ARRAY(module_props));
+
+	return 0;
+
+error:
+	impl_destroy(impl);
+	return res;
+}