text: /* Spa
   *
   * Copyright © 2020 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 <errno.h>
  #include <stddef.h>
  #include <unistd.h>
  #include <string.h>
  #include <stdio.h>
  
  #include <spa/support/plugin.h>
  #include <spa/support/log.h>
  #include <spa/support/system.h>
  #include <spa/support/loop.h>
  #include <spa/utils/list.h>
  #include <spa/utils/keys.h>
  #include <spa/utils/json.h>
  #include <spa/utils/string.h>
  #include <spa/node/node.h>
  #include <spa/node/utils.h>
  #include <spa/node/io.h>
  #include <spa/node/keys.h>
  #include <spa/param/audio/format-utils.h>
  #include <spa/debug/types.h>
  #include <spa/param/audio/type-info.h>
  #include <spa/param/param.h>
  #include <spa/pod/filter.h>
  #include <spa/control/control.h>
  
  #define NAME "null-audio-sink"
  
  struct props {
  	uint32_t channels;
  	uint32_t rate;
  	uint32_t n_pos;
  	uint32_t pos[SPA_AUDIO_MAX_CHANNELS];
  };
  
  static void reset_props(struct props *props)
  {
  	props->channels = 0;
  	props->rate = 0;
  	props->n_pos = 0;
  }
  
  #define DEFAULT_CHANNELS	2
  #define DEFAULT_RATE		44100
  
  #define MAX_SAMPLES	8192
  #define MAX_BUFFERS	16
  #define MAX_PORTS	1
  
  struct buffer {
  	uint32_t id;
  #define BUFFER_FLAG_OUT	(1<<0)
  	uint32_t flags;
  	struct spa_buffer *outbuf;
  };
  
  struct impl;
  
  struct port {
  	uint64_t info_all;
  	struct spa_port_info info;
  	struct spa_param_info params[5];
  
  	struct spa_io_buffers *io;
  
  	bool have_format;
  	struct spa_audio_info current_format;
  	uint32_t blocks;
  	size_t bpf;
  
  	struct buffer buffers[MAX_BUFFERS];
  	uint32_t n_buffers;
  };
  
  struct impl {
  	struct spa_handle handle;
  	struct spa_node node;
  
  	struct spa_log *log;
  	struct spa_loop *data_loop;
  	struct spa_system *data_system;
  
  	struct props props;
  
  	uint64_t info_all;
  	struct spa_node_info info;
  	struct spa_param_info params[2];
  	struct spa_io_clock *clock;
  	struct spa_io_position *position;
  
  	struct spa_hook_list hooks;
  	struct spa_callbacks callbacks;
  
  	struct port port;
  
  	unsigned int started:1;
  	unsigned int following:1;
  	struct spa_source timer_source;
  	struct itimerspec timerspec;
  	uint64_t next_time;
  };
  
  #define CHECK_PORT(this,d,p)  ((d) == SPA_DIRECTION_INPUT && (p) < MAX_PORTS)
  
  static int impl_node_enum_params(void *object, int seq,
  			uint32_t id, uint32_t start, uint32_t num,
  			const struct spa_pod *filter)
  {
  	struct impl *this = object;
  	struct spa_pod *param;
  	struct spa_pod_builder b = { 0 };
  	uint8_t buffer[1024];
  	struct spa_result_node_params result;
  	uint32_t count = 0;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  	spa_return_val_if_fail(num != 0, -EINVAL);
  
  	result.id = id;
  	result.next = start;
        next:
  	result.index = result.next++;
  
  	spa_pod_builder_init(&b, buffer, sizeof(buffer));
  
  	switch (id) {
  	case SPA_PARAM_IO:
  	{
  		switch (result.index) {
  		case 0:
  			param = spa_pod_builder_add_object(&b,
  					SPA_TYPE_OBJECT_ParamIO, id,
  					SPA_PARAM_IO_id,	SPA_POD_Id(SPA_IO_Clock),
  					SPA_PARAM_IO_size,	SPA_POD_Int(sizeof(struct spa_io_clock)));
  			break;
  		case 1:
  			param = spa_pod_builder_add_object(&b,
  					SPA_TYPE_OBJECT_ParamIO, id,
  					SPA_PARAM_IO_id,	SPA_POD_Id(SPA_IO_Position),
  					SPA_PARAM_IO_size,	SPA_POD_Int(sizeof(struct spa_io_position)));
  			break;
  		default:
  			return 0;
  		}
  		break;
  	}
  	default:
  		return -ENOENT;
  	}
  
  	if (spa_pod_filter(&b, &result.param, param, filter) < 0)
  		goto next;
  
  	spa_node_emit_result(&this->hooks, seq, 0, SPA_RESULT_TYPE_NODE_PARAMS, &result);
  
  	if (++count != num)
  		goto next;
  
  	return 0;
  }
  
  static void set_timeout(struct impl *this, uint64_t next_time)
  {
  	spa_log_trace(this->log, "set timeout %"PRIu64, next_time);
  	this->timerspec.it_value.tv_sec = next_time / SPA_NSEC_PER_SEC;
  	this->timerspec.it_value.tv_nsec = next_time % SPA_NSEC_PER_SEC;
  	spa_system_timerfd_settime(this->data_system,
  			this->timer_source.fd, SPA_FD_TIMER_ABSTIME, &this->timerspec, NULL);
  }
  
  static int set_timers(struct impl *this)
  {
  	struct timespec now;
  	int res;
  
  	if ((res = spa_system_clock_gettime(this->data_system, CLOCK_MONOTONIC, &now)) < 0)
  	    return res;
  	this->next_time = SPA_TIMESPEC_TO_NSEC(&now);
  
  	if (this->following) {
  		set_timeout(this, 0);
  	} else {
  		set_timeout(this, this->next_time);
  	}
  	return 0;
  }
  
  static inline bool is_following(struct impl *this)
  {
  	return this->position && this->clock && this->position->clock.id != this->clock->id;
  }
  
  static int do_reassign_follower(struct spa_loop *loop,
  			    bool async,
  			    uint32_t seq,
  			    const void *data,
  			    size_t size,
  			    void *user_data)
  {
  	struct impl *this = user_data;
  	set_timers(this);
  	return 0;
  }
  
  static int reassign_follower(struct impl *this)
  {
  	bool following;
  
  	if (!this->started)
  		return 0;
  
  	following = is_following(this);
  	if (following != this->following) {
  		spa_log_debug(this->log, NAME" %p: reassign follower %d->%d", this, this->following, following);
  		this->following = following;
  		spa_loop_invoke(this->data_loop, do_reassign_follower, 0, NULL, 0, true, this);
  	}
  	return 0;
  }
  
  static int impl_node_set_io(void *object, uint32_t id, void *data, size_t size)
  {
  	struct impl *this = object;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	switch (id) {
  	case SPA_IO_Clock:
  		if (size > 0 && size < sizeof(struct spa_io_clock))
  			return -EINVAL;
  		this->clock = data;
  		break;
  	case SPA_IO_Position:
  		this->position = data;
  		break;
  	default:
  		return -ENOENT;
  	}
  	reassign_follower(this);
  
  	return 0;
  }
  
  static void on_timeout(struct spa_source *source)
  {
  	struct impl *this = source->data;
  	uint64_t expirations, nsec, duration = 10;
  	uint32_t rate;
  
  	spa_log_trace(this->log, "timeout");
  
  	if (spa_system_timerfd_read(this->data_system,
  				this->timer_source.fd, &expirations) < 0) {
  		if (errno == EAGAIN)
  			return;
  		perror("read timerfd");
  	}
  
  	nsec = this->next_time;
  
  	if (SPA_LIKELY(this->position)) {
  		duration = this->position->clock.duration;
  		rate = this->position->clock.rate.denom;
  	} else {
  		duration = 1024;
  		rate = 48000;
  	}
  
  	this->next_time = nsec + duration * SPA_NSEC_PER_SEC / rate;
  
  	if (SPA_LIKELY(this->clock)) {
  		this->clock->nsec = nsec;
  		this->clock->position += duration;
  		this->clock->duration = duration;
  		this->clock->delay = 0;
  		this->clock->rate_diff = 1.0;
  		this->clock->next_nsec = this->next_time;
  	}
  
  	spa_node_call_ready(&this->callbacks, SPA_STATUS_NEED_DATA);
  
  	set_timeout(this, this->next_time);
  }
  
  static int do_start(struct impl *this)
  {
  	if (this->started)
  		return 0;
  
  	this->following = is_following(this);
  	set_timers(this);
  	this->started = true;
  	return 0;
  }
  
  static int do_stop(struct impl *this)
  {
  	if (!this->started)
  		return 0;
  	this->started = false;
  	set_timeout(this, 0);
  	return 0;
  }
  
  static int impl_node_send_command(void *object, const struct spa_command *command)
  {
  	struct impl *this = object;
  	struct port *port;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  	spa_return_val_if_fail(command != NULL, -EINVAL);
  
  	port = &this->port;
  
  	switch (SPA_NODE_COMMAND_ID(command)) {
  	case SPA_NODE_COMMAND_Start:
  	{
  		if (!port->have_format)
  			return -EIO;
  		if (port->n_buffers == 0)
  			return -EIO;
  
  		do_start(this);
  		break;
  	}
  	case SPA_NODE_COMMAND_Suspend:
  	case SPA_NODE_COMMAND_Pause:
  		do_stop(this);
  		break;
  
  	default:
  		return -ENOTSUP;
  	}
  	return 0;
  }
  
  static const struct spa_dict_item node_info_items[] = {
  	{ SPA_KEY_NODE_DRIVER, "true" },
  };
  
  static void emit_node_info(struct impl *this, bool full)
  {
  	uint64_t old = full ? this->info.change_mask : 0;
  	if (full)
  		this->info.change_mask = this->info_all;
  	if (this->info.change_mask) {
  		this->info.props = &SPA_DICT_INIT_ARRAY(node_info_items);
  		spa_node_emit_info(&this->hooks, &this->info);
  		this->info.change_mask = old;
  	}
  }
  
  static void emit_port_info(struct impl *this, struct port *port, bool full)
  {
  	uint64_t old = full ? port->info.change_mask : 0;
  	if (full)
  		port->info.change_mask = port->info_all;
  	if (port->info.change_mask) {
  		spa_node_emit_port_info(&this->hooks,
  				SPA_DIRECTION_INPUT, 0, &port->info);
  		port->info.change_mask = old;
  	}
  }
  
  static int
  impl_node_add_listener(void *object,
  		struct spa_hook *listener,
  		const struct spa_node_events *events,
  		void *data)
  {
  	struct impl *this = object;
  	struct spa_hook_list save;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	spa_hook_list_isolate(&this->hooks, &save, listener, events, data);
  
  	emit_node_info(this, true);
  	emit_port_info(this, &this->port, true);
  
  	spa_hook_list_join(&this->hooks, &save);
  
  	return 0;
  }
  
  static int
  impl_node_set_callbacks(void *object,
  			const struct spa_node_callbacks *callbacks,
  			void *data)
  {
  	struct impl *this = object;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	this->callbacks = SPA_CALLBACKS_INIT(callbacks, data);
  
  	return 0;
  }
  
  static int
  port_enum_formats(struct impl *this,
  		  enum spa_direction direction, uint32_t port_id,
  		  uint32_t index,
  		  struct spa_pod **param,
  		  struct spa_pod_builder *builder)
  {
  	struct spa_pod_frame f[1];
  
  	switch (index) {
  	case 0:
  		spa_pod_builder_push_object(builder, &f[0],
  			SPA_TYPE_OBJECT_Format, SPA_PARAM_EnumFormat);
  		spa_pod_builder_add(builder,
  			SPA_FORMAT_mediaType,      SPA_POD_Id(SPA_MEDIA_TYPE_audio),
  			SPA_FORMAT_mediaSubtype,   SPA_POD_Id(SPA_MEDIA_SUBTYPE_raw),
  			SPA_FORMAT_AUDIO_format,   SPA_POD_CHOICE_ENUM_Id(3,
  								SPA_AUDIO_FORMAT_F32P,
  								SPA_AUDIO_FORMAT_F32P,
  								SPA_AUDIO_FORMAT_F32),
  			0);
  
  		if (this->props.rate != 0) {
  			spa_pod_builder_add(builder,
  				SPA_FORMAT_AUDIO_rate, SPA_POD_Int(this->props.rate),
  				0);
  		} else {
  			spa_pod_builder_add(builder,
  				SPA_FORMAT_AUDIO_rate, SPA_POD_CHOICE_RANGE_Int(DEFAULT_RATE, 1, INT32_MAX),
  				0);
  		}
  		if (this->props.channels != 0) {
  			spa_pod_builder_add(builder,
  				SPA_FORMAT_AUDIO_channels, SPA_POD_Int(this->props.channels),
  				0);
  		} else {
  			spa_pod_builder_add(builder,
  				SPA_FORMAT_AUDIO_channels, SPA_POD_CHOICE_RANGE_Int(DEFAULT_CHANNELS, 1, INT32_MAX),
  				0);
  		}
  		if (this->props.n_pos != 0) {
  			spa_pod_builder_prop(builder, SPA_FORMAT_AUDIO_position, 0);
  			spa_pod_builder_array(builder, sizeof(uint32_t), SPA_TYPE_Id,
  					this->props.n_pos, this->props.pos);
  		}
  		*param = spa_pod_builder_pop(builder, &f[0]);
  		break;
  	default:
  		return 0;
  	}
  	return 1;
  }
  
  static int
  impl_node_port_enum_params(void *object, int seq,
  			enum spa_direction direction, uint32_t port_id,
  			uint32_t id, uint32_t start, uint32_t num,
  			const struct spa_pod *filter)
  {
  	struct impl *this = object;
  	struct port *port;
  	struct spa_pod_builder b = { 0 };
  	uint8_t buffer[1024];
  	struct spa_pod *param;
  	struct spa_result_node_params result;
  	uint32_t count = 0;
  	int res;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  	spa_return_val_if_fail(num != 0, -EINVAL);
  
  	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), -EINVAL);
  
  	port = &this->port;
  
  	result.id = id;
  	result.next = start;
        next:
  	result.index = result.next++;
  
  	spa_pod_builder_init(&b, buffer, sizeof(buffer));
  
  	switch (id) {
  	case SPA_PARAM_EnumFormat:
  		if ((res = port_enum_formats(this, direction, port_id,
  						result.index, &param, &b)) <= 0)
  			return res;
  		break;
  
  	case SPA_PARAM_Format:
  		if (!port->have_format)
  			return -EIO;
  		if (result.index > 0)
  			return 0;
  
  		param = spa_format_audio_raw_build(&b, id, &port->current_format.info.raw);
  		break;
  
  	case SPA_PARAM_Buffers:
  		if (!port->have_format)
  			return -EIO;
  		if (result.index > 0)
  			return 0;
  
  		param = spa_pod_builder_add_object(&b,
  			SPA_TYPE_OBJECT_ParamBuffers, id,
  			SPA_PARAM_BUFFERS_buffers, SPA_POD_CHOICE_RANGE_Int(1, 1, MAX_BUFFERS),
  			SPA_PARAM_BUFFERS_blocks,  SPA_POD_Int(port->blocks),
  			SPA_PARAM_BUFFERS_size,    SPA_POD_CHOICE_RANGE_Int(
  							MAX_SAMPLES * port->bpf,
  							16 * port->bpf,
  							INT32_MAX),
  			SPA_PARAM_BUFFERS_stride,  SPA_POD_Int(port->bpf),
  			SPA_PARAM_BUFFERS_align,   SPA_POD_Int(16));
  		break;
  	case SPA_PARAM_IO:
  		switch (result.index) {
  		case 0:
  			param = spa_pod_builder_add_object(&b,
  				SPA_TYPE_OBJECT_ParamIO, id,
  				SPA_PARAM_IO_id,   SPA_POD_Id(SPA_IO_Buffers),
  				SPA_PARAM_IO_size, SPA_POD_Int(sizeof(struct spa_io_buffers)));
  			break;
  		default:
  			return 0;
  		}
  		break;
  	default:
  		return -ENOENT;
  	}
  
  	if (spa_pod_filter(&b, &result.param, param, filter) < 0)
  		goto next;
  
  	spa_node_emit_result(&this->hooks, seq, 0, SPA_RESULT_TYPE_NODE_PARAMS, &result);
  
  	if (++count != num)
  		goto next;
  
  	return 0;
  }
  
  static int clear_buffers(struct impl *this, struct port *port)
  {
  	if (port->n_buffers > 0) {
  		spa_log_info(this->log, NAME " %p: clear buffers", this);
  		port->n_buffers = 0;
  		this->started = false;
  	}
  	return 0;
  }
  
  static int
  port_set_format(struct impl *this,
  		enum spa_direction direction,
  		uint32_t port_id,
  		uint32_t flags,
  		const struct spa_pod *format)
  {
  	int res;
  	struct port *port = &this->port;
  
  	if (format == NULL) {
  		port->have_format = false;
  		clear_buffers(this, port);
  	} else {
  		struct spa_audio_info info = { 0 };
  
  		if ((res = spa_format_parse(format, &info.media_type, &info.media_subtype)) < 0)
  			return res;
  
  		if (info.media_type != SPA_MEDIA_TYPE_audio ||
  		    info.media_subtype != SPA_MEDIA_SUBTYPE_raw)
  			return -EINVAL;
  
  		if (spa_format_audio_raw_parse(format, &info.info.raw) < 0)
  			return -EINVAL;
  
  		if (info.info.raw.format == SPA_AUDIO_FORMAT_F32) {
  			port->bpf = 4 * info.info.raw.channels;
  			port->blocks = 1;
  		} else if (info.info.raw.format == SPA_AUDIO_FORMAT_F32P) {
  			port->bpf = 4;
  			port->blocks = info.info.raw.channels;
  		} else
  			return -EINVAL;
  
  		port->current_format = info;
  		port->have_format = true;
  	}
  
  	port->info.change_mask |= SPA_PORT_CHANGE_MASK_PARAMS;
  	if (port->have_format) {
  		port->info.change_mask |= SPA_PORT_CHANGE_MASK_RATE;
  		port->info.rate = SPA_FRACTION(1, port->current_format.info.raw.rate);
  		port->params[1] = SPA_PARAM_INFO(SPA_PARAM_Format, SPA_PARAM_INFO_READWRITE);
  		port->params[3] = SPA_PARAM_INFO(SPA_PARAM_Buffers, SPA_PARAM_INFO_READ);
  	} else {
  		port->params[1] = SPA_PARAM_INFO(SPA_PARAM_Format, SPA_PARAM_INFO_WRITE);
  		port->params[3] = SPA_PARAM_INFO(SPA_PARAM_Buffers, 0);
  	}
  	emit_port_info(this, port, false);
  
  	return 0;
  }
  
  static int
  impl_node_port_set_param(void *object,
  			 enum spa_direction direction, uint32_t port_id,
  			 uint32_t id, uint32_t flags,
  			 const struct spa_pod *param)
  {
  	struct impl *this = object;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), -EINVAL);
  
  	switch (id) {
  	case SPA_PARAM_Format:
  		return port_set_format(this, direction, port_id, flags, param);
  	default:
  		return -ENOENT;
  	}
  	return 0;
  }
  
  static int
  impl_node_port_use_buffers(void *object,
  			   enum spa_direction direction,
  			   uint32_t port_id,
  			   uint32_t flags,
  			   struct spa_buffer **buffers,
  			   uint32_t n_buffers)
  {
  	struct impl *this = object;
  	struct port *port;
  	uint32_t i;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), -EINVAL);
  
  	port = &this->port;
  
  	if (!port->have_format)
  		return -EIO;
  
  	clear_buffers(this, port);
  
  	for (i = 0; i < n_buffers; i++) {
  		struct buffer *b;
  		struct spa_data *d = buffers[i]->datas;
  
  		b = &port->buffers[i];
  		b->id = i;
  		b->flags = 0;
  		b->outbuf = buffers[i];
  
  		if (d[0].data == NULL) {
  			spa_log_error(this->log, NAME " %p: invalid memory on buffer %p", this,
  				      buffers[i]);
  			return -EINVAL;
  		}
  	}
  	port->n_buffers = n_buffers;
  
  	return 0;
  }
  
  static int
  impl_node_port_set_io(void *object,
  		      enum spa_direction direction,
  		      uint32_t port_id,
  		      uint32_t id,
  		      void *data, size_t size)
  {
  	struct impl *this = object;
  	struct port *port;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), -EINVAL);
  
  	port = &this->port;
  
  	switch (id) {
  	case SPA_IO_Buffers:
  		port->io = data;
  		break;
  	default:
  		return -ENOENT;
  	}
  	return 0;
  }
  
  static int impl_node_process(void *object)
  {
  	struct impl *this = object;
  	struct port *port;
  	struct spa_io_buffers *io;
  
  	spa_return_val_if_fail(this != NULL, -EINVAL);
  
  	port = &this->port;
  
  	io = port->io;
  	spa_return_val_if_fail(io != NULL, -EIO);
  
  	if (io->status != SPA_STATUS_HAVE_DATA)
  		return io->status;
  	if (io->buffer_id >= port->n_buffers) {
  		io->status = -EINVAL;
  		return io->status;
  	}
  	io->status = SPA_STATUS_OK;
  	return SPA_STATUS_HAVE_DATA;
  }
  
  static const struct spa_node_methods impl_node = {
  	SPA_VERSION_NODE_METHODS,
  	.add_listener = impl_node_add_listener,
  	.set_callbacks = impl_node_set_callbacks,
  	.enum_params = impl_node_enum_params,
  	.set_io = impl_node_set_io,
  	.send_command = impl_node_send_command,
  	.port_enum_params = impl_node_port_enum_params,
  	.port_set_param = impl_node_port_set_param,
  	.port_use_buffers = impl_node_port_use_buffers,
  	.port_set_io = impl_node_port_set_io,
  	.process = impl_node_process,
  };
  
  static int impl_get_interface(struct spa_handle *handle, const char *type, void **interface)
  {
  	struct impl *this;
  
  	spa_return_val_if_fail(handle != NULL, -EINVAL);
  	spa_return_val_if_fail(interface != NULL, -EINVAL);
  
  	this = (struct impl *) handle;
  
  	if (spa_streq(type, SPA_TYPE_INTERFACE_Node))
  		*interface = &this->node;
  	else
  		return -ENOENT;
  
  	return 0;
  }
  
  static int impl_clear(struct spa_handle *handle)
  {
  	struct impl *this;
  
  	spa_return_val_if_fail(handle != NULL, -EINVAL);
  
  	this = (struct impl *) handle;
  
  	spa_loop_remove_source(this->data_loop, &this->timer_source);
  	spa_system_close(this->data_system, this->timer_source.fd);
  
  	return 0;
  }
  
  static size_t
  impl_get_size(const struct spa_handle_factory *factory,
  	      const struct spa_dict *params)
  {
  	return sizeof(struct impl);
  }
  
  static uint32_t channel_from_name(const char *name)
  {
  	int i;
  	for (i = 0; spa_type_audio_channel[i].name; i++) {
  		if (spa_streq(name, spa_debug_type_short_name(spa_type_audio_channel[i].name)))
  			return spa_type_audio_channel[i].type;
  	}
  	return SPA_AUDIO_CHANNEL_UNKNOWN;
  }
  
  static inline void parse_position(struct impl *this, 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);
  
  	this->props.n_pos = 0;
  	while (spa_json_get_string(&it[1], v, sizeof(v)) > 0 &&
  	    this->props.n_pos < SPA_AUDIO_MAX_CHANNELS) {
  		this->props.pos[this->props.n_pos++] = channel_from_name(v);
  	}
  }
  
  static int
  impl_init(const struct spa_handle_factory *factory,
  	  struct spa_handle *handle,
  	  const struct spa_dict *info,
  	  const struct spa_support *support,
  	  uint32_t n_support)
  {
  	struct impl *this;
  	struct port *port;
  	uint32_t i;
  
  	spa_return_val_if_fail(factory != NULL, -EINVAL);
  	spa_return_val_if_fail(handle != NULL, -EINVAL);
  
  	handle->get_interface = impl_get_interface;
  	handle->clear = impl_clear;
  
  	this = (struct impl *) handle;
  
  	this->log = spa_support_find(support, n_support, SPA_TYPE_INTERFACE_Log);
  	this->data_loop = spa_support_find(support, n_support, SPA_TYPE_INTERFACE_DataLoop);
  	this->data_system = spa_support_find(support, n_support, SPA_TYPE_INTERFACE_DataSystem);
  
  	if (this->data_loop == NULL) {
  		spa_log_error(this->log, "a data_loop is needed");
  		return -EINVAL;
  	}
  	if (this->data_system == NULL) {
  		spa_log_error(this->log, "a data_system is needed");
  		return -EINVAL;
  	}
  
  	spa_hook_list_init(&this->hooks);
  
  	this->node.iface = SPA_INTERFACE_INIT(
  			SPA_TYPE_INTERFACE_Node,
  			SPA_VERSION_NODE,
  			&impl_node, this);
  
  	this->info_all |= SPA_NODE_CHANGE_MASK_FLAGS |
  			SPA_NODE_CHANGE_MASK_PROPS |
  			SPA_NODE_CHANGE_MASK_PARAMS;
  	this->info = SPA_NODE_INFO_INIT();
  	this->info.max_input_ports = 1;
  	this->info.flags = SPA_NODE_FLAG_RT;
  	this->params[0] = SPA_PARAM_INFO(SPA_PARAM_IO, SPA_PARAM_INFO_READ);
  	this->info.params = this->params;
  	this->info.n_params = 1;
  	reset_props(&this->props);
  
  	port = &this->port;
  	port->info_all = SPA_PORT_CHANGE_MASK_FLAGS |
  			SPA_PORT_CHANGE_MASK_PARAMS;
  	port->info = SPA_PORT_INFO_INIT();
  	port->info.flags = SPA_PORT_FLAG_NO_REF |
  			SPA_PORT_FLAG_LIVE;
  	port->params[0] = SPA_PARAM_INFO(SPA_PARAM_EnumFormat, SPA_PARAM_INFO_READ);
  	port->params[1] = SPA_PARAM_INFO(SPA_PARAM_Format, SPA_PARAM_INFO_WRITE);
  	port->params[2] = SPA_PARAM_INFO(SPA_PARAM_IO, SPA_PARAM_INFO_READ);
  	port->params[3] = SPA_PARAM_INFO(SPA_PARAM_Buffers, 0);
  	port->info.params = port->params;
  	port->info.n_params = 4;
  
  	this->timer_source.func = on_timeout;
  	this->timer_source.data = this;
  	this->timer_source.fd = spa_system_timerfd_create(this->data_system, CLOCK_MONOTONIC,
  							  SPA_FD_CLOEXEC | SPA_FD_NONBLOCK);
  	this->timer_source.mask = SPA_IO_IN;
  	this->timer_source.rmask = 0;
  	this->timerspec.it_value.tv_sec = 0;
  	this->timerspec.it_value.tv_nsec = 0;
  	this->timerspec.it_interval.tv_sec = 0;
  	this->timerspec.it_interval.tv_nsec = 0;
  
  	spa_loop_add_source(this->data_loop, &this->timer_source);
  
  	for (i = 0; info && i < info->n_items; i++) {
  		const char *k = info->items[i].key;
  		const char *s = info->items[i].value;
  		if (spa_streq(k, SPA_KEY_AUDIO_CHANNELS)) {
  			this->props.channels = atoi(s);
  		} else if (spa_streq(k, SPA_KEY_AUDIO_RATE)) {
  			this->props.rate = atoi(s);
  		} else if (spa_streq(k, SPA_KEY_AUDIO_POSITION)) {
  			parse_position(this, s, strlen(s));
  		}
  	}
  	if (this->props.n_pos > 0)
  		this->props.channels = this->props.n_pos;
  
  	spa_log_info(this->log, NAME " %p: initialized", this);
  
  	return 0;
  }
  
  static const struct spa_interface_info impl_interfaces[] = {
  	{SPA_TYPE_INTERFACE_Node,},
  };
  
  static int
  impl_enum_interface_info(const struct spa_handle_factory *factory,
  			 const struct spa_interface_info **info,
  			 uint32_t *index)
  {
  	spa_return_val_if_fail(factory != NULL, -EINVAL);
  	spa_return_val_if_fail(info != NULL, -EINVAL);
  	spa_return_val_if_fail(index != NULL, -EINVAL);
  
  	switch (*index) {
  	case 0:
  		*info = &impl_interfaces[*index];
  		break;
  	default:
  		return 0;
  	}
  	(*index)++;
  
  	return 1;
  }
  
  static const struct spa_dict_item info_items[] = {
  	{ SPA_KEY_FACTORY_AUTHOR, "Wim Taymans <wim.taymans@gmail.com>" },
  	{ SPA_KEY_FACTORY_DESCRIPTION, "Consume audio samples" },
  };
  
  static const struct spa_dict info = SPA_DICT_INIT_ARRAY(info_items);
  
  const struct spa_handle_factory spa_support_null_audio_sink_factory = {
  	SPA_VERSION_HANDLE_FACTORY,
  	"support.null-audio-sink",
  	&info,
  	impl_get_size,
  	impl_init,
  	impl_enum_interface_info,
  };
  