Initial binding version

Signed-off-by: George Kiagiadakis <george.kiagiadakis@collabora.com>
Change-Id: I89e493d88c7fa1309f1b2991d346fc496caa6898

4 files changed, 1019 insertions, 0 deletions

diff --git a/binding/CMakeLists.txt b/binding/CMakeLists.txt
new file mode 100644
index 0000000..587d137
--- /dev/null
+++ b/binding/CMakeLists.txt
@@ -0,0 +1,20 @@
+PROJECT_TARGET_ADD(audiomixer-binding)
+
+	add_definitions(-DAFB_BINDING_VERSION=3)
+	add_definitions(-DBUILDING_APPFW_BINDING)
+
+	set(audiomixer_SOURCES
+		audiomixer-binding.c
+		audiomixer.c
+	)
+
+	add_library(${TARGET_NAME} MODULE ${audiomixer_SOURCES})
+
+	SET_TARGET_PROPERTIES(${TARGET_NAME} PROPERTIES
+		PREFIX "libafm-"
+		LABELS "BINDING"
+		LINK_FLAGS ${BINDINGS_LINK_FLAG}
+		OUTPUT_NAME ${TARGET_NAME}
+	)
+
+	TARGET_LINK_LIBRARIES(${TARGET_NAME} ${link_libraries})
diff --git a/binding/audiomixer-binding.c b/binding/audiomixer-binding.c
new file mode 100644
index 0000000..005f5c7
--- /dev/null
+++ b/binding/audiomixer-binding.c
@@ -0,0 +1,342 @@
+/*
+ * Copyright © 2019 Collabora Ltd.
+ *   @author George Kiagiadakis <george.kiagiadakis@collabora.com>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#include <string.h>
+#include <json-c/json.h>
+#include <afb/afb-binding.h>
+#include <systemd/sd-event.h>
+#include "audiomixer.h"
+
+static struct audiomixer *audiomixer;
+static afb_event_t controls_changed;
+static afb_event_t volume_changed;
+static afb_event_t mute_changed;
+static sd_event_source *controls_changed_source;
+
+static int
+audiomixer_controls_changed_deferred(sd_event_source *s, void *data)
+{
+	afb_event_push(controls_changed, NULL);
+
+	sd_event_source_unref(controls_changed_source);
+	controls_changed_source = NULL;
+	return 0;
+}
+
+struct value_changed_data
+{
+	unsigned int change_mask;
+	struct mixer_control control;
+	sd_event_source *source;
+};
+
+static int
+audiomixer_value_changed_deferred(sd_event_source *s, void *data)
+{
+	struct value_changed_data *d = data;
+	json_object *json;
+
+	json = json_object_new_object();
+	json_object_object_add(json, "control",
+		json_object_new_string(d->control.name));
+
+	if (d->change_mask & MIXER_CONTROL_CHANGE_FLAG_VOLUME) {
+		json_object_object_add(json, "value",
+			json_object_new_double(d->control.volume));
+		afb_event_push(volume_changed, json);
+	} else if (d->change_mask & MIXER_CONTROL_CHANGE_FLAG_MUTE) {
+		json_object_object_add(json, "value",
+			json_object_new_int(d->control.mute));
+		afb_event_push(mute_changed, json);
+	}
+
+	sd_event_source_unref(d->source);
+	free(d);
+	return 0;
+}
+
+/* called in audiomixer's thread */
+static void
+audiomixer_controls_changed(void *data)
+{
+	sd_event *e = afb_daemon_get_event_loop();
+	sd_event_add_defer(e, &controls_changed_source,
+		audiomixer_controls_changed_deferred, NULL);
+}
+
+
+/* called in audiomixer's thread */
+static void
+audiomixer_value_changed(void *data,
+	unsigned int change_mask,
+	const struct mixer_control *control)
+{
+	sd_event *e = afb_daemon_get_event_loop();
+	struct value_changed_data *d = calloc(1, sizeof(*d));
+
+	d->change_mask = change_mask;
+	d->control = *control;
+
+	if (sd_event_add_defer(e, &d->source,
+			audiomixer_value_changed_deferred, d) < 0)
+		free(d);
+}
+
+static const struct audiomixer_events audiomixer_events = {
+	.controls_changed = audiomixer_controls_changed,
+	.value_changed = audiomixer_value_changed,
+};
+
+static int
+cleanup(sd_event_source *s, void *data)
+{
+	audiomixer_free(audiomixer);
+	audiomixer = NULL;
+	return 0;
+}
+
+static int
+init(afb_api_t api)
+{
+	sd_event *e = afb_daemon_get_event_loop();
+
+	controls_changed = afb_api_make_event(api, "controls_changed");
+	volume_changed = afb_api_make_event(api, "volume_changed");
+	mute_changed = afb_api_make_event(api, "mute_changed");
+
+	audiomixer = audiomixer_new();
+	sd_event_add_exit(e, NULL, cleanup, NULL);
+
+	audiomixer_add_event_listener(audiomixer, &audiomixer_events, NULL);
+
+	return 0;
+}
+
+static void
+list_controls_cb(afb_req_t request)
+{
+	json_object *ret_json, *nest_json;
+	const struct mixer_control **ctls;
+	unsigned int n_controls, i;
+
+	audiomixer_lock(audiomixer);
+
+	if (audiomixer_ensure_connected(audiomixer, 3) < 0) {
+		afb_req_fail(request, "failed",
+			"Could not connect to the PipeWire daemon");
+		goto unlock;
+	}
+
+	if (audiomixer_ensure_controls(audiomixer, 3) < 0) {
+		AFB_REQ_NOTICE(request, "No mixer controls were exposed "
+			"in PipeWire after 3 seconds");
+	}
+
+	ctls = audiomixer_get_active_controls(audiomixer, &n_controls);
+
+	ret_json = json_object_new_array();
+	for (i = 0; i < n_controls; i++) {
+		nest_json = json_object_new_object();
+		json_object_object_add(nest_json, "control",
+				json_object_new_string(ctls[i]->name));
+		json_object_object_add(nest_json, "volume",
+				json_object_new_double(ctls[i]->volume));
+		json_object_object_add(nest_json, "mute",
+				json_object_new_int(ctls[i]->mute));
+		json_object_array_add(ret_json, nest_json);
+	}
+	afb_req_success(request, ret_json, NULL);
+
+unlock:
+	audiomixer_unlock(audiomixer);
+}
+
+static void
+volume_cb(afb_req_t request)
+{
+	json_object *ret_json;
+	const char *control = afb_req_value(request, "control");
+	const char *value = afb_req_value(request, "value");
+	const struct mixer_control *ctl;
+	double volume;
+
+	audiomixer_lock(audiomixer);
+
+	if (!control) {
+		afb_req_fail(request, "failed",
+			"Invalid arguments: missing 'control'");
+		goto unlock;
+	}
+
+	if (audiomixer_ensure_connected(audiomixer, 3) < 0) {
+		afb_req_fail(request, "failed",
+			"Could not connect to the PipeWire daemon");
+		goto unlock;
+	}
+
+	if (audiomixer_ensure_controls(audiomixer, 3) < 0) {
+		AFB_REQ_NOTICE(request, "No mixer controls were exposed "
+			"in PipeWire after 3 seconds");
+	}
+
+	ctl = audiomixer_find_control(audiomixer, control);
+	if (!ctl) {
+		afb_req_fail(request, "failed", "Could not find control");
+		goto unlock;
+	}
+
+	if(value) {
+		char *endptr;
+		volume = strtod(value, &endptr);
+		if (endptr == value || volume < -0.00001 || volume > 1.00001) {
+			afb_req_fail(request, "failed",
+				"Invalid volume value (must be between 0.0 and 1.0)");
+			goto unlock;
+		}
+
+		audiomixer_change_volume(audiomixer, ctl, volume);
+	} else {
+		volume = ctl->volume;
+	}
+
+	ret_json = json_object_new_object();
+	json_object_object_add(ret_json, "volume", json_object_new_double(volume));
+	afb_req_success(request, ret_json, NULL);
+
+unlock:
+	audiomixer_unlock(audiomixer);
+}
+
+static void
+mute_cb(afb_req_t request)
+{
+	json_object *ret_json;
+	const char *control = afb_req_value(request, "control");
+	const char *value = afb_req_value(request, "value");
+	const struct mixer_control *ctl;
+	int mute;
+
+	audiomixer_lock(audiomixer);
+
+	if (!control) {
+		afb_req_fail(request, "failed",
+			"Invalid arguments: missing 'control'");
+		goto unlock;
+	}
+
+	if (audiomixer_ensure_connected(audiomixer, 3) < 0) {
+		afb_req_fail(request, "failed",
+			"Could not connect to the PipeWire daemon");
+		goto unlock;
+	}
+
+	if (audiomixer_ensure_controls(audiomixer, 3) < 0) {
+		AFB_REQ_NOTICE(request, "No mixer controls were exposed "
+			"in PipeWire after 3 seconds");
+	}
+
+	ctl = audiomixer_find_control(audiomixer, control);
+	if (!ctl) {
+		afb_req_fail(request, "failed", "Could not find control");
+		goto unlock;
+	}
+
+	if(value) {
+		char *endptr;
+		mute = (int) strtol(value, &endptr, 10);
+		if (endptr == value || mute < 0 || mute > 1) {
+			afb_req_fail(request, "failed",
+				"Invalid mute value (must be integer 0 or 1)");
+			goto unlock;
+		}
+
+		audiomixer_change_mute(audiomixer, ctl, mute);
+	} else {
+		mute = ctl->mute;
+	}
+
+	ret_json = json_object_new_object();
+	json_object_object_add(ret_json, "mute", json_object_new_int(mute));
+	afb_req_success(request, ret_json, NULL);
+
+unlock:
+	audiomixer_unlock(audiomixer);
+}
+
+static void
+subscribe_cb(afb_req_t request)
+{
+	const char *eventstr = afb_req_value(request, "event");
+	afb_event_t event;
+
+	if (!eventstr) {
+		afb_req_fail(request, "failed",
+			"Invalid arguments: missing 'event'");
+		return;
+	}
+
+	if (!strcmp(eventstr, "controls_changed"))
+		event = controls_changed;
+	else if (!strcmp(eventstr, "volume_changed"))
+		event = volume_changed;
+	else if (!strcmp(eventstr, "mute_changed"))
+		event = mute_changed;
+	else {
+		afb_req_fail(request, "failed", "Invalid event name");
+		return;
+	}
+
+	if (afb_req_subscribe(request, event) != 0)
+		afb_req_fail(request, "failed", "Failed to subscribe to event");
+	else
+		afb_req_success(request, NULL, "Subscribed");
+}
+
+static void
+unsubscribe_cb(afb_req_t request)
+{
+	const char *eventstr = afb_req_value(request, "event");
+	afb_event_t event;
+
+	if (!eventstr) {
+		afb_req_fail(request, "failed",
+			"Invalid arguments: missing 'event'");
+		return;
+	}
+
+	if (!strcmp(eventstr, "controls_changed"))
+		event = controls_changed;
+	else if (!strcmp(eventstr, "volume_changed"))
+		event = volume_changed;
+	else if (!strcmp(eventstr, "mute_changed"))
+		event = mute_changed;
+	else {
+		afb_req_fail(request, "failed", "Invalid event name");
+		return;
+	}
+
+	if (afb_req_unsubscribe(request, event) != 0)
+		afb_req_fail(request, "failed", "Failed to unsubscribe from event");
+	else
+		afb_req_success(request, NULL, "Unsubscribed");
+}
+
+static const afb_verb_t verbs[]= {
+	{ .verb = "list_controls", .callback = list_controls_cb, .info = "List the available controls" },
+	{ .verb = "volume",        .callback = volume_cb,        .info = "Get/Set volume" },
+	{ .verb = "mute",          .callback = mute_cb,          .info = "Get/Set mute" },
+	{ .verb = "subscribe",     .callback = subscribe_cb,     .info = "Subscribe to mixer events" },
+	{ .verb = "unsubscribe",   .callback = unsubscribe_cb,   .info = "Unsubscribe from mixer events" },
+	{ }
+};
+
+const afb_binding_t afbBindingV3 = {
+	.api  = "audiomixer",
+	.specification = "AudioMixer API",
+	.verbs = verbs,
+	.init = init,
+};
diff --git a/binding/audiomixer.c b/binding/audiomixer.c
new file mode 100644
index 0000000..c4ccc12
--- /dev/null
+++ b/binding/audiomixer.c
@@ -0,0 +1,597 @@
+/*
+ * Copyright © 2019 Collabora Ltd.
+ *   @author George Kiagiadakis <george.kiagiadakis@collabora.com>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#include "audiomixer.h"
+#include <pipewire/pipewire.h>
+#include <pipewire/array.h>
+#include <pipewire/extensions/endpoint.h>
+
+#if !defined(BUILDING_APPFW_BINDING)
+#define debug(...) fprintf(stdout, __VA_ARGS__)
+#else
+#include <afb/afb-binding.h>
+#define debug(...) AFB_DEBUG(__VA_ARGS__)
+#endif
+
+struct audiomixer
+{
+	struct pw_thread_loop *main_loop;
+
+	struct pw_core *core;
+	struct pw_remote *remote;
+	struct spa_hook remote_listener;
+
+	struct pw_core_proxy *core_proxy;
+	struct spa_hook remote_core_listener;
+	struct pw_registry_proxy *registry_proxy;
+	struct spa_hook registry_listener;
+
+	struct pw_array endpoints;
+	struct pw_array all_mixer_controls;
+
+	const struct audiomixer_events *events;
+	void *events_data;
+};
+
+enum endpoint_state {
+	EP_STATE_INITIAL,
+	EP_STATE_COLLECT_ENUM_STREAM,
+	EP_STATE_COLLECT_ENUM_CONTROL,
+	EP_STATE_COLLECT_CONTROL,
+	EP_STATE_ACTIVE,
+};
+
+struct endpoint
+{
+	struct audiomixer *audiomixer;
+	struct pw_endpoint_proxy *proxy;
+
+	struct pw_properties *properties;
+	enum endpoint_state state;
+
+	struct spa_hook proxy_listener;
+	struct spa_hook endpoint_listener;
+
+	struct pw_array mixer_controls;
+};
+
+struct mixer_control_impl
+{
+	struct mixer_control pub;
+	struct endpoint *endpoint;
+	uint32_t stream_id;
+	uint32_t volume_control_id;
+	uint32_t mute_control_id;
+};
+
+static void
+emit_controls_changed(struct audiomixer *self)
+{
+	pw_thread_loop_signal(self->main_loop, false);
+
+	if (!self->events || !self->events->controls_changed)
+		return;
+
+	self->events->controls_changed(self->events_data);
+}
+
+static void
+emit_value_changed(struct audiomixer *self,
+	unsigned int change_mask,
+	struct mixer_control *ctl)
+{
+	if (!self->events || !self->events->value_changed)
+		return;
+
+	self->events->value_changed(self->events_data, change_mask, ctl);
+}
+
+static void
+advance_endpoint_state(struct endpoint *endpoint)
+{
+	debug("%p advance endpoint state, was:%d", endpoint, endpoint->state);
+
+	switch (endpoint->state) {
+	case EP_STATE_INITIAL:
+		endpoint->state = EP_STATE_COLLECT_ENUM_STREAM;
+		pw_endpoint_proxy_enum_params(endpoint->proxy, 0,
+			PW_ENDPOINT_PARAM_EnumStream, 0, -1, NULL);
+		pw_proxy_sync((struct pw_proxy *) endpoint->proxy, 0);
+		break;
+	case EP_STATE_COLLECT_ENUM_STREAM:
+		endpoint->state = EP_STATE_COLLECT_ENUM_CONTROL;
+		pw_endpoint_proxy_enum_params(endpoint->proxy, 0,
+			PW_ENDPOINT_PARAM_EnumControl, 0, -1, NULL);
+		pw_proxy_sync((struct pw_proxy *) endpoint->proxy, 0);
+		break;
+	case EP_STATE_COLLECT_ENUM_CONTROL: {
+		uint32_t ids[1] = { PW_ENDPOINT_PARAM_Control };
+
+		endpoint->state = EP_STATE_COLLECT_CONTROL;
+		pw_endpoint_proxy_subscribe_params(endpoint->proxy, ids, 1);
+		pw_proxy_sync((struct pw_proxy *) endpoint->proxy, 0);
+		break;
+	}
+	case EP_STATE_COLLECT_CONTROL: {
+		struct mixer_control_impl *ctl;
+		struct audiomixer *self = endpoint->audiomixer;
+
+		endpoint->state = EP_STATE_ACTIVE;
+		pw_array_for_each(ctl, &endpoint->mixer_controls) {
+			pw_array_add_ptr(&self->all_mixer_controls, ctl);
+		}
+		emit_controls_changed(self);
+		break;
+	}
+	default:
+		break;
+	}
+}
+
+static void
+endpoint_param (void *object, int seq, uint32_t id,
+		uint32_t index, uint32_t next,
+		const struct spa_pod *param)
+{
+	struct endpoint *endpoint = object;
+	struct mixer_control_impl *ctl;
+	const struct spa_pod_prop *prop;
+	struct spa_pod_object *obj = (struct spa_pod_object *) param;
+
+	if (!spa_pod_is_object(param)) {
+		debug("endpoint_param: bad param - not an object");
+		return;
+	}
+
+	switch (id) {
+	case PW_ENDPOINT_PARAM_EnumStream:
+		/* verify conditions */
+		if (endpoint->state != EP_STATE_COLLECT_ENUM_STREAM) {
+			debug("endpoint_param EnumStream: wrong state");
+			return;
+		}
+		if (SPA_POD_OBJECT_TYPE(obj) != PW_ENDPOINT_OBJECT_ParamStream) {
+			debug("endpoint_param EnumStream: invalid param");
+			return;
+		}
+
+		/* create new mixer control */
+		ctl = pw_array_add(&endpoint->mixer_controls, sizeof(*ctl));
+		ctl->endpoint = endpoint;
+
+		SPA_POD_OBJECT_FOREACH(obj, prop) {
+			switch (prop->key) {
+			case PW_ENDPOINT_PARAM_STREAM_id:
+				spa_pod_get_int(&prop->value, &ctl->stream_id);
+				break;
+			case PW_ENDPOINT_PARAM_STREAM_name:
+				spa_pod_copy_string(&prop->value,
+					SPA_N_ELEMENTS(ctl->pub.name),
+					ctl->pub.name);
+				break;
+			default:
+				break;
+			}
+		}
+		break;
+
+	case PW_ENDPOINT_PARAM_EnumControl: {
+		uint32_t tmp_id = -1;
+		const char *name = NULL;
+
+		/* verify conditions */
+		if (endpoint->state != EP_STATE_COLLECT_ENUM_CONTROL) {
+			debug("endpoint_param EnumControl: wrong state");
+			return;
+		}
+		if (SPA_POD_OBJECT_TYPE(obj) != PW_ENDPOINT_OBJECT_ParamControl) {
+			debug("endpoint_param EnumControl: invalid param");
+			return;
+		}
+
+		/* find the mixer control */
+		prop = spa_pod_object_find_prop(obj, NULL,
+			PW_ENDPOINT_PARAM_CONTROL_stream_id);
+		if (prop)
+			spa_pod_get_int(&prop->value, &tmp_id);
+		else {
+			debug("endpoint_param EnumControl: invalid control without stream");
+			return;
+		}
+
+		pw_array_for_each(ctl, &endpoint->mixer_controls) {
+			if (ctl->stream_id == tmp_id)
+				break;
+		}
+
+		/* check if we reached the end of the array
+		 * without finding the stream */
+		if (!pw_array_check(&endpoint->mixer_controls, ctl)) {
+			debug("endpoint_param EnumControl: could not find "
+				"stream id %u", tmp_id);
+			return;
+		}
+
+		/* store the control id based on the control's name */
+		prop = spa_pod_object_find_prop(obj, NULL,
+			PW_ENDPOINT_PARAM_CONTROL_name);
+		if (prop)
+			spa_pod_get_string(&prop->value, &name);
+		else {
+			debug("endpoint_param EnumControl: invalid control without name");
+			return;
+		}
+
+		prop = spa_pod_object_find_prop(obj, NULL,
+			PW_ENDPOINT_PARAM_CONTROL_id);
+		if (!prop) {
+			debug("endpoint_param EnumControl: invalid control without id");
+			return;
+		}
+
+		if (strcmp (name, "volume")) {
+			spa_pod_get_int(&prop->value, &ctl->volume_control_id);
+			prop = spa_pod_object_find_prop(obj, NULL,
+				PW_ENDPOINT_PARAM_CONTROL_type);
+		} else if (strcmp (name, "mute")) {
+			spa_pod_get_int(&prop->value, &ctl->mute_control_id);
+		}
+
+		break;
+	}
+	case PW_ENDPOINT_PARAM_Control: {
+		uint32_t tmp_id = -1;
+
+		/* verify conditions */
+		if (endpoint->state != EP_STATE_COLLECT_CONTROL ||
+		    endpoint->state != EP_STATE_ACTIVE) {
+			debug("endpoint_param Control: wrong state");
+			return;
+		}
+		if (SPA_POD_OBJECT_TYPE(obj) != PW_ENDPOINT_OBJECT_ParamControl) {
+			debug("endpoint_param Control: invalid param");
+			return;
+		}
+
+		/* match the control id and set the value */
+		prop = spa_pod_object_find_prop(obj, NULL,
+			PW_ENDPOINT_PARAM_CONTROL_id);
+		if (prop)
+			spa_pod_get_int(&prop->value, &tmp_id);
+		else {
+			debug("endpoint_param Control: invalid control without id");
+			return;
+		}
+
+		prop = spa_pod_object_find_prop(obj, NULL,
+			PW_ENDPOINT_PARAM_CONTROL_value);
+		if (!prop) {
+			debug("endpoint_param Control: invalid control without value");
+			return;
+		}
+
+		pw_array_for_each(ctl, &endpoint->mixer_controls) {
+			if (ctl->volume_control_id == tmp_id) {
+				spa_pod_get_double(&prop->value, &ctl->pub.volume);
+
+				if (endpoint->state == EP_STATE_ACTIVE) {
+					emit_value_changed(endpoint->audiomixer,
+						MIXER_CONTROL_CHANGE_FLAG_VOLUME,
+						&ctl->pub);
+				}
+				break;
+			} else if (ctl->mute_control_id == tmp_id) {
+				spa_pod_get_bool(&prop->value, &ctl->pub.mute);
+
+				if (endpoint->state == EP_STATE_ACTIVE) {
+					emit_value_changed(endpoint->audiomixer,
+						MIXER_CONTROL_CHANGE_FLAG_MUTE,
+						&ctl->pub);
+				}
+				break;
+			}
+		}
+
+		break;
+	}
+	default:
+		break;
+	}
+}
+
+struct pw_endpoint_proxy_events endpoint_events = {
+	PW_VERSION_ENDPOINT_PROXY_EVENTS,
+	.param = endpoint_param,
+};
+
+static void
+endpoint_proxy_destroyed(void *object)
+{
+	struct endpoint *endpoint = object;
+	struct audiomixer *self = endpoint->audiomixer;
+	struct mixer_control_impl *ctl;
+	struct mixer_control **ctlptr;
+	struct endpoint **epptr;
+
+	debug("%p endpoint destroyed", endpoint);
+
+	if (endpoint->properties)
+		pw_properties_free(endpoint->properties);
+
+	pw_array_for_each(ctl, &endpoint->mixer_controls) {
+		pw_array_for_each(ctlptr, &self->all_mixer_controls) {
+			if (*ctlptr == &ctl->pub) {
+				pw_array_remove(&self->all_mixer_controls, ctlptr);
+				break;
+			}
+		}
+	}
+	emit_controls_changed(self);
+	pw_array_clear(&endpoint->mixer_controls);
+
+	pw_array_for_each(epptr, &self->endpoints) {
+		if (*epptr == endpoint) {
+			pw_array_remove(&self->endpoints, epptr);
+			break;
+		}
+	}
+}
+
+static void
+endpoint_proxy_done(void *object, int seq)
+{
+	struct endpoint *endpoint = object;
+	advance_endpoint_state(endpoint);
+}
+
+struct pw_proxy_events proxy_events = {
+	PW_VERSION_PROXY_EVENTS,
+	.destroy = endpoint_proxy_destroyed,
+	.done = endpoint_proxy_done,
+};
+
+static void
+registry_event_global(void *data, uint32_t id, uint32_t parent_id,
+		uint32_t permissions, uint32_t type, uint32_t version,
+		const struct spa_dict *props)
+{
+	struct audiomixer *self = data;
+	const char *media_class;
+	struct pw_proxy *proxy;
+	struct endpoint *endpoint;
+
+	if (type != PW_TYPE_INTERFACE_Endpoint)
+		return;
+
+	/* we are only interested in mixer endpoints */
+	media_class = props ? spa_dict_lookup(props, "media.class") : NULL;
+	if (!media_class || strcmp(media_class, "Mixer/Audio") != 0)
+		return;
+
+	proxy = pw_registry_proxy_bind(self->registry_proxy,
+		id, type, PW_VERSION_ENDPOINT, sizeof(struct endpoint));
+
+	endpoint = pw_proxy_get_user_data(proxy);
+	endpoint->audiomixer = self;
+	endpoint->proxy = (struct pw_endpoint_proxy *) proxy;
+	endpoint->properties = props ? pw_properties_new_dict(props) : NULL;
+	endpoint->state = EP_STATE_INITIAL;
+	pw_array_init(&endpoint->mixer_controls, 4 * sizeof(struct mixer_control));
+
+	pw_proxy_add_listener(proxy, &endpoint->proxy_listener,
+		&proxy_events, endpoint);
+	pw_endpoint_proxy_add_listener(endpoint->proxy,
+		&endpoint->endpoint_listener,
+		&endpoint_events, endpoint);
+
+	debug("%p added endpoint: %u", endpoint, id);
+
+	pw_array_add_ptr(&self->endpoints, endpoint);
+	advance_endpoint_state(endpoint);
+}
+
+
+static const struct pw_registry_proxy_events registry_events = {
+	PW_VERSION_REGISTRY_PROXY_EVENTS,
+	.global = registry_event_global,
+};
+
+static void
+on_remote_state_changed(void *data, enum pw_remote_state old,
+		enum pw_remote_state state, const char *error)
+{
+	struct audiomixer *self = data;
+
+	if (state == PW_REMOTE_STATE_CONNECTED) {
+		self->core_proxy = pw_remote_get_core_proxy(self->remote);
+		self->registry_proxy = pw_core_proxy_get_registry(
+			self->core_proxy,
+			PW_TYPE_INTERFACE_Registry,
+			PW_VERSION_REGISTRY, 0);
+		pw_registry_proxy_add_listener(self->registry_proxy,
+			&self->registry_listener,
+			&registry_events, self);
+	}
+
+	pw_thread_loop_signal(self->main_loop, false);
+}
+
+static const struct pw_remote_events remote_events = {
+	PW_VERSION_REMOTE_EVENTS,
+	.state_changed = on_remote_state_changed,
+};
+
+struct audiomixer *
+audiomixer_new(void)
+{
+	struct audiomixer *self;
+	struct pw_loop *loop;
+
+	pw_init(NULL, NULL);
+
+	self = calloc(1, sizeof(struct audiomixer));
+	loop = pw_loop_new(NULL);
+	self->main_loop = pw_thread_loop_new(loop, "audiomixer-loop");
+	self->core = pw_core_new(loop, NULL, 0);
+	self->remote = pw_remote_new(self->core, NULL, 0);
+	pw_array_init(&self->endpoints, 1 * sizeof(void*));
+	pw_array_init(&self->all_mixer_controls, 8 * sizeof(void*));
+
+	pw_module_load(self->core, "libpipewire-module-endpoint", NULL, NULL,
+		NULL, NULL);
+	pw_thread_loop_start(self->main_loop);
+
+	return self;
+}
+
+void
+audiomixer_free(struct audiomixer *self)
+{
+	struct pw_loop *loop;
+
+	pw_thread_loop_lock(self->main_loop);
+	self->events = NULL;
+	self->events_data = NULL;
+	pw_remote_disconnect(self->remote);
+	pw_thread_loop_unlock(self->main_loop);
+	pw_thread_loop_stop(self->main_loop);
+
+	pw_array_clear(&self->endpoints);
+	pw_array_clear(&self->all_mixer_controls);
+	pw_remote_destroy(self->remote);
+	pw_core_destroy(self->core);
+
+	loop = pw_thread_loop_get_loop(self->main_loop);
+	pw_thread_loop_destroy(self->main_loop);
+	pw_loop_destroy(loop);
+
+	free(self);
+}
+
+void
+audiomixer_lock(struct audiomixer *self)
+{
+	pw_thread_loop_lock(self->main_loop);
+}
+
+void
+audiomixer_unlock(struct audiomixer *self)
+{
+	pw_thread_loop_unlock(self->main_loop);
+}
+
+int
+audiomixer_ensure_connected(struct audiomixer *self, int timeout_sec)
+{
+	enum pw_remote_state state;
+	int res;
+
+	state = pw_remote_get_state(self->remote, NULL);
+	if (state == PW_REMOTE_STATE_CONNECTED)
+		return 0;
+
+	if ((res = pw_remote_connect(self->remote)) < 0)
+		return res;
+
+	while (true) {
+		state = pw_remote_get_state(self->remote, NULL);
+		if (state == PW_REMOTE_STATE_CONNECTED)
+			return 0;
+		else if (state == PW_REMOTE_STATE_ERROR)
+			return -EIO;
+
+		if (pw_thread_loop_timed_wait(self->main_loop, timeout_sec) != 0)
+			return -ETIMEDOUT;
+	}
+}
+
+int
+audiomixer_ensure_controls(struct audiomixer *self, int timeout_sec)
+{
+	while (pw_array_get_len(&self->all_mixer_controls, void*) == 0) {
+		if (pw_thread_loop_timed_wait(self->main_loop, timeout_sec) != 0)
+			return -ETIMEDOUT;
+	}
+	return 0;
+}
+
+const struct mixer_control **
+audiomixer_get_active_controls(struct audiomixer *self,
+	unsigned int *n_controls)
+{
+	const struct mixer_control **ret;
+
+	*n_controls = pw_array_get_len(&self->all_mixer_controls, void*);
+	ret = (const struct mixer_control **)
+		pw_array_first(&self->all_mixer_controls);
+
+	return ret;
+}
+
+const struct mixer_control *
+audiomixer_find_control(struct audiomixer *self, const char *name)
+{
+	struct mixer_control **ctlptr;
+
+	pw_array_for_each(ctlptr, &self->all_mixer_controls) {
+		if (!strcmp((*ctlptr)->name, name)) {
+			return *ctlptr;
+		}
+	}
+	return NULL;
+}
+
+void
+audiomixer_add_event_listener(struct audiomixer *self,
+	const struct audiomixer_events *events,
+	void *data)
+{
+	self->events = events;
+	self->events_data = data;
+}
+
+void
+audiomixer_change_volume(struct audiomixer *self,
+	const struct mixer_control *control,
+	double volume)
+{
+	const struct mixer_control_impl *impl =
+		(const struct mixer_control_impl *) control;
+	struct endpoint *endpoint = impl->endpoint;
+	char buffer[1024];
+	struct spa_pod_builder b = SPA_POD_BUILDER_INIT(buffer, 1024);
+	struct spa_pod *param;
+
+	param = spa_pod_builder_add_object(&b,
+		PW_ENDPOINT_OBJECT_ParamControl, PW_ENDPOINT_PARAM_Control,
+		PW_ENDPOINT_PARAM_CONTROL_id, SPA_POD_Int(impl->volume_control_id),
+		PW_ENDPOINT_PARAM_CONTROL_value, SPA_POD_Double(volume),
+		NULL);
+	pw_endpoint_proxy_set_param(endpoint->proxy,
+		PW_ENDPOINT_PARAM_Control, 0, param);
+}
+
+void
+audiomixer_change_mute(struct audiomixer *self,
+	const struct mixer_control *control,
+	bool mute)
+{
+	const struct mixer_control_impl *impl =
+		(const struct mixer_control_impl *) control;
+	struct endpoint *endpoint = impl->endpoint;
+	char buffer[1024];
+	struct spa_pod_builder b = SPA_POD_BUILDER_INIT(buffer, 1024);
+	struct spa_pod *param;
+
+	param = spa_pod_builder_add_object(&b,
+		PW_ENDPOINT_OBJECT_ParamControl, PW_ENDPOINT_PARAM_Control,
+		PW_ENDPOINT_PARAM_CONTROL_id, SPA_POD_Int(impl->mute_control_id),
+		PW_ENDPOINT_PARAM_CONTROL_value, SPA_POD_Bool(mute),
+		NULL);
+	pw_endpoint_proxy_set_param(endpoint->proxy,
+		PW_ENDPOINT_PARAM_Control, 0, param);
+}
diff --git a/binding/audiomixer.h b/binding/audiomixer.h
new file mode 100644
index 0000000..f4e83c7
--- /dev/null
+++ b/binding/audiomixer.h
@@ -0,0 +1,60 @@
+/*
+ * Copyright © 2019 Collabora Ltd.
+ *   @author George Kiagiadakis <george.kiagiadakis@collabora.com>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#include <stdbool.h>
+
+struct audiomixer;
+
+struct mixer_control
+{
+	char name[32];
+	double volume;
+	bool mute;
+};
+
+struct audiomixer_events
+{
+	void (*controls_changed) (void *data);
+
+	void (*value_changed) (void *data,
+#define MIXER_CONTROL_CHANGE_FLAG_VOLUME (1<<0)
+#define MIXER_CONTROL_CHANGE_FLAG_MUTE   (1<<1)
+				unsigned int change_mask,
+				const struct mixer_control *control);
+};
+
+struct audiomixer * audiomixer_new(void);
+void audiomixer_free(struct audiomixer *self);
+
+/* locking is required to call any of the methods below
+ * and to access any structure maintained by audiomixer */
+void audiomixer_lock(struct audiomixer *self);
+void audiomixer_unlock(struct audiomixer *self);
+
+int audiomixer_ensure_connected(struct audiomixer *self, int timeout_sec);
+int audiomixer_ensure_controls(struct audiomixer *self, int timeout_sec);
+
+const struct mixer_control ** audiomixer_get_active_controls(
+	struct audiomixer *self,
+	unsigned int *n_controls);
+
+const struct mixer_control * audiomixer_find_control(
+	struct audiomixer *self,
+	const char *name);
+
+void audiomixer_add_event_listener(struct audiomixer *self,
+	const struct audiomixer_events *events,
+	void *data);
+
+void audiomixer_change_volume(struct audiomixer *self,
+	const struct mixer_control *control,
+	double volume);
+
+void audiomixer_change_mute(struct audiomixer *self,
+	const struct mixer_control *control,
+	bool mute);
+