pipewire/spa/plugins/v4l2/v4l2-source.c

/* Spa V4l2 Source
 * Copyright (C) 2016 Wim Taymans <wim.taymans@gmail.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include <stddef.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include <linux/videodev2.h>

#include <spa/node.h>
#include <spa/video/format-utils.h>
#include <spa/clock.h>
#include <spa/list.h>
#include <spa/log.h>
#include <spa/loop.h>
#include <spa/param-alloc.h>
#include <spa/type-map.h>
#include <spa/format-builder.h>
#include <lib/debug.h>
#include <lib/props.h>

#define NAME "v4l2-source"

static const char default_device[] = "/dev/video0";

struct props {
	char device[64];
	char device_name[128];
	int device_fd;
};

static void reset_props(struct props *props)
{
	strncpy(props->device, default_device, 64);
}

#define MAX_BUFFERS     64

struct buffer {
	struct spa_buffer *outbuf;
	struct spa_meta_header *h;
	bool outstanding;
	bool allocated;
	struct v4l2_buffer v4l2_buffer;
};

struct type {
	uint32_t node;
	uint32_t clock;
	uint32_t format;
	uint32_t props;
	uint32_t prop_device;
	uint32_t prop_device_name;
	uint32_t prop_device_fd;
	struct spa_type_media_type media_type;
	struct spa_type_media_subtype media_subtype;
	struct spa_type_media_subtype_video media_subtype_video;
	struct spa_type_format_video format_video;
	struct spa_type_video_format video_format;
	struct spa_type_event_node event_node;
	struct spa_type_command_node command_node;
	struct spa_type_param_alloc_buffers param_alloc_buffers;
	struct spa_type_param_alloc_meta_enable param_alloc_meta_enable;
	struct spa_type_meta meta;
	struct spa_type_data data;
};

static inline void init_type(struct type *type, struct spa_type_map *map)
{
	type->node = spa_type_map_get_id(map, SPA_TYPE__Node);
	type->clock = spa_type_map_get_id(map, SPA_TYPE__Clock);
	type->format = spa_type_map_get_id(map, SPA_TYPE__Format);
	type->props = spa_type_map_get_id(map, SPA_TYPE__Props);
	type->prop_device = spa_type_map_get_id(map, SPA_TYPE_PROPS__device);
	type->prop_device_name = spa_type_map_get_id(map, SPA_TYPE_PROPS__deviceName);
	type->prop_device_fd = spa_type_map_get_id(map, SPA_TYPE_PROPS__deviceFd);
	spa_type_media_type_map(map, &type->media_type);
	spa_type_media_subtype_map(map, &type->media_subtype);
	spa_type_media_subtype_video_map(map, &type->media_subtype_video);
	spa_type_format_video_map(map, &type->format_video);
	spa_type_video_format_map(map, &type->video_format);
	spa_type_event_node_map(map, &type->event_node);
	spa_type_command_node_map(map, &type->command_node);
	spa_type_param_alloc_buffers_map(map, &type->param_alloc_buffers);
	spa_type_param_alloc_meta_enable_map(map, &type->param_alloc_meta_enable);
	spa_type_meta_map(map, &type->meta);
	spa_type_data_map(map, &type->data);
}

struct port {
	struct spa_log *log;
	struct spa_loop *main_loop;
	struct spa_loop *data_loop;

	bool export_buf;
	bool started;

	bool next_fmtdesc;
	struct v4l2_fmtdesc fmtdesc;
	bool next_frmsize;
	struct v4l2_frmsizeenum frmsize;
	struct v4l2_frmivalenum frmival;

	bool have_format;
	struct spa_video_info current_format;
	uint8_t format_buffer[1024];

	int fd;
	bool opened;
	struct v4l2_capability cap;
	struct v4l2_format fmt;
	enum v4l2_buf_type type;
	enum v4l2_memory memtype;

	struct buffer buffers[MAX_BUFFERS];
	uint32_t n_buffers;

	bool source_enabled;
	struct spa_source source;

	struct spa_port_info info;
	uint8_t params_buffer[1024];
	struct spa_port_io *io;

	int64_t last_ticks;
	int64_t last_monotonic;
};

struct impl {
	struct spa_handle handle;
	struct spa_node node;
	struct spa_clock clock;

	struct spa_type_map *map;
	struct spa_log *log;
	struct type type;

	uint32_t seq;

	uint8_t props_buffer[512];
	struct props props;

	const struct spa_node_callbacks *callbacks;
	void *callbacks_data;

	struct port out_ports[1];
};

#define CHECK_PORT(this,direction,port_id)  ((direction) == SPA_DIRECTION_OUTPUT && (port_id) == 0)


#define PROP(f,key,type,...)							\
	SPA_POD_PROP (f,key,0,type,1,__VA_ARGS__)
#define PROP_R(f,key,type,...)							\
	SPA_POD_PROP (f,key,SPA_POD_PROP_FLAG_READONLY,type,1,__VA_ARGS__)
#define PROP_MM(f,key,type,...)							\
	SPA_POD_PROP (f,key,SPA_POD_PROP_RANGE_MIN_MAX,type,3,__VA_ARGS__)
#define PROP_U_MM(f,key,type,...)						\
	SPA_POD_PROP (f,key,SPA_POD_PROP_FLAG_UNSET |				\
		SPA_POD_PROP_RANGE_MIN_MAX,type,3,__VA_ARGS__)
#define PROP_EN(f,key,type,n,...)						\
	SPA_POD_PROP (f,key,SPA_POD_PROP_RANGE_ENUM,type,n,__VA_ARGS__)
#define PROP_U_EN(f,key,type,n,...)						\
	SPA_POD_PROP (f,key,SPA_POD_PROP_FLAG_UNSET |				\
		SPA_POD_PROP_RANGE_ENUM,type,n,__VA_ARGS__)
#include "v4l2-utils.c"

static int impl_node_get_props(struct spa_node *node, struct spa_props **props)
{
	struct impl *this;
	struct spa_pod_builder b = { NULL, };
	struct spa_pod_frame f[2];

	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);
	spa_return_val_if_fail(props != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = SPA_CONTAINER_OF(node, struct impl, node);

	spa_pod_builder_init(&b, this->props_buffer, sizeof(this->props_buffer));
	spa_pod_builder_props(&b, &f[0], this->type.props,
		PROP(&f[1], this->type.prop_device, -SPA_POD_TYPE_STRING,
			this->props.device, sizeof(this->props.device)),
		PROP_R(&f[1], this->type.prop_device_name, -SPA_POD_TYPE_STRING,
			this->props.device_name, sizeof(this->props.device_name)),
		PROP_R(&f[1], this->type.prop_device_fd, SPA_POD_TYPE_INT,
			this->props.device_fd));
	*props = SPA_POD_BUILDER_DEREF(&b, f[0].ref, struct spa_props);

	return SPA_RESULT_OK;
}

static int impl_node_set_props(struct spa_node *node, const struct spa_props *props)
{
	struct impl *this;

	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = SPA_CONTAINER_OF(node, struct impl, node);

	if (props == NULL) {
		reset_props(&this->props);
		return SPA_RESULT_OK;
	} else {
		spa_props_query(props, this->type.prop_device, -SPA_POD_TYPE_STRING,
				this->props.device, sizeof(this->props.device), 0);
	}
	return SPA_RESULT_OK;
}

static int do_pause_done(struct spa_loop *loop,
			 bool async,
			 uint32_t seq,
			 size_t size,
			 const void *data,
			 void *user_data)
{
	struct impl *this = user_data;
	int res = *(int*)data;

	if (SPA_RESULT_IS_OK(res))
		res = spa_v4l2_stream_off(this);

	this->callbacks->done(this->callbacks_data, seq, res);

	return SPA_RESULT_OK;
}

static int do_pause(struct spa_loop *loop,
		    bool async,
		    uint32_t seq,
		    size_t size,
		    const void *data,
		    void *user_data)
{
	struct impl *this = user_data;
	int res;
	const struct spa_command *cmd = data;

	res = spa_node_port_send_command(&this->node, SPA_DIRECTION_OUTPUT, 0, cmd);

	if (async) {
		spa_loop_invoke(this->out_ports[0].main_loop,
				do_pause_done,
				seq,
				sizeof(res),
				&res,
				false,
				this);
	}
	return res;
}

static int do_start_done(struct spa_loop *loop,
			 bool async,
			 uint32_t seq,
			 size_t size,
			 const void *data,
			 void *user_data)
{
	struct impl *this = user_data;
	int res = *(int*)data;

	this->callbacks->done(this->callbacks_data, seq, res);

	return SPA_RESULT_OK;
}

static int do_start(struct spa_loop *loop,
		    bool async,
		    uint32_t seq,
		    size_t size,
		    const void *data,
		    void *user_data)
{
	struct impl *this = user_data;
	int res;
	const struct spa_command *cmd = data;

	res = spa_node_port_send_command(&this->node, SPA_DIRECTION_OUTPUT, 0, cmd);

	if (async) {
		spa_loop_invoke(this->out_ports[0].main_loop,
				do_start_done,
				seq,
				sizeof(res),
				&res,
				false,
				this);
	}
	return SPA_RESULT_OK;
}

static int impl_node_send_command(struct spa_node *node, const struct spa_command *command)
{
	struct impl *this;

	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);
	spa_return_val_if_fail(command != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = SPA_CONTAINER_OF(node, struct impl, node);

	if (SPA_COMMAND_TYPE(command) == this->type.command_node.Start) {
		struct port *state = &this->out_ports[0];
		int res;

		if (!state->have_format)
			return SPA_RESULT_NO_FORMAT;

		if (state->n_buffers == 0)
			return SPA_RESULT_NO_BUFFERS;

		if ((res = spa_v4l2_stream_on(this)) < 0)
			return res;

		return spa_loop_invoke(this->out_ports[0].data_loop,
				       do_start,
				       ++this->seq,
				       SPA_POD_SIZE(command),
				       command,
				       false,
				       this);
	} else if (SPA_COMMAND_TYPE(command) == this->type.command_node.Pause) {
		struct port *state = &this->out_ports[0];

		if (!state->have_format)
			return SPA_RESULT_NO_FORMAT;

		if (state->n_buffers == 0)
			return SPA_RESULT_NO_BUFFERS;

		return spa_loop_invoke(this->out_ports[0].data_loop,
				       do_pause,
				       ++this->seq,
				       SPA_POD_SIZE(command),
				       command,
				       false,
				       this);
	} else if (SPA_COMMAND_TYPE(command) == this->type.command_node.ClockUpdate) {
		return SPA_RESULT_OK;
	} else
		return SPA_RESULT_NOT_IMPLEMENTED;
}

static int impl_node_set_callbacks(struct spa_node *node,
				   const struct spa_node_callbacks *callbacks,
				   void *data)
{
	struct impl *this;

	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = SPA_CONTAINER_OF(node, struct impl, node);

	this->callbacks = callbacks;
	this->callbacks_data = data;

	return SPA_RESULT_OK;
}

static int
impl_node_get_n_ports(struct spa_node *node,
		      uint32_t *n_input_ports,
		      uint32_t *max_input_ports,
		      uint32_t *n_output_ports,
		      uint32_t *max_output_ports)
{
	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	if (n_input_ports)
		*n_input_ports = 0;
	if (max_input_ports)
		*max_input_ports = 0;
	if (n_output_ports)
		*n_output_ports = 1;
	if (max_output_ports)
		*max_output_ports = 1;

	return SPA_RESULT_OK;
}

static int impl_node_get_port_ids(struct spa_node *node,
				  uint32_t n_input_ports,
				  uint32_t *input_ids,
				  uint32_t n_output_ports,
				  uint32_t *output_ids)
{
	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	if (n_output_ports > 0 && output_ids != NULL)
		output_ids[0] = 0;

	return SPA_RESULT_OK;
}


static int impl_node_add_port(struct spa_node *node,
			      enum spa_direction direction,
			      uint32_t port_id)
{
	return SPA_RESULT_NOT_IMPLEMENTED;
}

static int impl_node_remove_port(struct spa_node *node,
		                 enum spa_direction direction,
				 uint32_t port_id)
{
	return SPA_RESULT_NOT_IMPLEMENTED;
}

static int
impl_node_port_enum_formats(struct spa_node *node,
			    enum spa_direction direction,
			    uint32_t port_id,
			    struct spa_format **format,
			    const struct spa_format *filter,
			    uint32_t index)
{
	struct impl *this;
	int res;

	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);
	spa_return_val_if_fail(format != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = SPA_CONTAINER_OF(node, struct impl, node);

	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), SPA_RESULT_INVALID_PORT);

	res = spa_v4l2_enum_format(this, format, filter, index);

	return res;
}

static int impl_node_port_set_format(struct spa_node *node,
				     enum spa_direction direction,
				     uint32_t port_id,
				     uint32_t flags,
				     const struct spa_format *format)
{
	struct impl *this;
	struct port *state;
	struct spa_video_info info;

	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = SPA_CONTAINER_OF(node, struct impl, node);

	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), SPA_RESULT_INVALID_PORT);

	state = &this->out_ports[port_id];

	if (format == NULL) {
		spa_v4l2_stream_off(this);
		spa_v4l2_clear_buffers(this);
		spa_v4l2_close(this);
		state->have_format = false;
		return SPA_RESULT_OK;
	} else {
		info.media_type = SPA_FORMAT_MEDIA_TYPE(format);
		info.media_subtype = SPA_FORMAT_MEDIA_SUBTYPE(format);

		if (info.media_type != this->type.media_type.video) {
			spa_log_error(this->log, "media type must be video");
			return SPA_RESULT_INVALID_MEDIA_TYPE;
		}

		if (info.media_subtype == this->type.media_subtype.raw) {
			if (!spa_format_video_raw_parse(format, &info.info.raw, &this->type.format_video)) {
				spa_log_error(this->log, "can't parse video raw");
				return SPA_RESULT_INVALID_MEDIA_TYPE;
			}

			if (state->have_format && info.media_type == state->current_format.media_type &&
			    info.media_subtype == state->current_format.media_subtype &&
			    info.info.raw.format == state->current_format.info.raw.format &&
			    info.info.raw.size.width == state->current_format.info.raw.size.width &&
			    info.info.raw.size.height == state->current_format.info.raw.size.height)
				return SPA_RESULT_OK;
		} else if (info.media_subtype == this->type.media_subtype_video.mjpg) {
			if (!spa_format_video_mjpg_parse(format, &info.info.mjpg, &this->type.format_video))
				return SPA_RESULT_INVALID_MEDIA_TYPE;

			if (state->have_format && info.media_type == state->current_format.media_type &&
			    info.media_subtype == state->current_format.media_subtype &&
			    info.info.mjpg.size.width == state->current_format.info.mjpg.size.width &&
			    info.info.mjpg.size.height == state->current_format.info.mjpg.size.height)
				return SPA_RESULT_OK;
		} else if (info.media_subtype == this->type.media_subtype_video.h264) {
			if (!spa_format_video_h264_parse(format, &info.info.h264, &this->type.format_video))
				return SPA_RESULT_INVALID_MEDIA_TYPE;

			if (state->have_format && info.media_type == state->current_format.media_type &&
			    info.media_subtype == state->current_format.media_subtype &&
			    info.info.h264.size.width == state->current_format.info.h264.size.width &&
			    info.info.h264.size.height == state->current_format.info.h264.size.height)
				return SPA_RESULT_OK;
		}
	}

	if (state->have_format && !(flags & SPA_PORT_FORMAT_FLAG_TEST_ONLY)) {
		spa_v4l2_use_buffers(this, NULL, 0);
		state->have_format = false;
	}

	if (spa_v4l2_set_format(this, &info, flags & SPA_PORT_FORMAT_FLAG_TEST_ONLY) < 0)
		return SPA_RESULT_INVALID_MEDIA_TYPE;

	if (!(flags & SPA_PORT_FORMAT_FLAG_TEST_ONLY)) {
		state->current_format = info;
		state->have_format = true;
	}

	return SPA_RESULT_OK;
}

static int impl_node_port_get_format(struct spa_node *node,
				     enum spa_direction direction,
				     uint32_t port_id,
				     const struct spa_format **format)
{
	struct impl *this;
	struct port *state;
	struct spa_pod_builder b = { NULL, };
	struct spa_pod_frame f[2];

	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);
	spa_return_val_if_fail(format != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = SPA_CONTAINER_OF(node, struct impl, node);

	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), SPA_RESULT_INVALID_PORT);

	state = &this->out_ports[port_id];

	if (!state->have_format)
		return SPA_RESULT_NO_FORMAT;

	b.data = state->format_buffer;
	b.size = sizeof(state->format_buffer);

	spa_pod_builder_push_format(&b, &f[0], this->type.format,
			state->current_format.media_type,
			state->current_format.media_subtype);

	if (state->current_format.media_subtype == this->type.media_subtype.raw) {
		spa_pod_builder_add(&b,
			PROP(&f[1], this->type.format_video.format, SPA_POD_TYPE_ID,
				state->current_format.info.raw.format),
			PROP(&f[1], this->type.format_video.size, -SPA_POD_TYPE_RECTANGLE,
				&state->current_format.info.raw.size),
			PROP(&f[1], this->type.format_video.framerate, -SPA_POD_TYPE_FRACTION,
				&state->current_format.info.raw.framerate), 0);
	} else if (state->current_format.media_subtype == this->type.media_subtype_video.mjpg ||
		   state->current_format.media_subtype == this->type.media_subtype_video.jpeg) {
		spa_pod_builder_add(&b,
			PROP(&f[1], this->type.format_video.size, -SPA_POD_TYPE_RECTANGLE,
				&state->current_format.info.mjpg.size),
			PROP(&f[1], this->type.format_video.framerate, -SPA_POD_TYPE_FRACTION,
				&state->current_format.info.mjpg.framerate), 0);
	} else if (state->current_format.media_subtype == this->type.media_subtype_video.h264) {
		spa_pod_builder_add(&b,
			PROP(&f[1], this->type.format_video.size, -SPA_POD_TYPE_RECTANGLE,
				&state->current_format.info.h264.size),
			PROP(&f[1], this->type.format_video.framerate, -SPA_POD_TYPE_FRACTION,
				&state->current_format.info.h264.framerate), 0);
	} else
		return SPA_RESULT_NO_FORMAT;

	spa_pod_builder_pop(&b, &f[0]);

	*format = SPA_POD_BUILDER_DEREF(&b, f[0].ref, struct spa_format);

	return SPA_RESULT_OK;
}

static int impl_node_port_get_info(struct spa_node *node,
				   enum spa_direction direction,
				   uint32_t port_id,
				   const struct spa_port_info **info)
{
	struct impl *this;

	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);
	spa_return_val_if_fail(info != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = SPA_CONTAINER_OF(node, struct impl, node);

	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), SPA_RESULT_INVALID_PORT);

	*info = &this->out_ports[port_id].info;

	return SPA_RESULT_OK;
}

static int impl_node_port_enum_params(struct spa_node *node,
				      enum spa_direction direction,
				      uint32_t port_id,
				      uint32_t index,
				      struct spa_param **param)
{

	struct impl *this;
	struct port *state;
	struct spa_pod_builder b = { NULL, };
	struct spa_pod_frame f[2];

	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);
	spa_return_val_if_fail(param != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = SPA_CONTAINER_OF(node, struct impl, node);

	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), SPA_RESULT_INVALID_PORT);

	state = &this->out_ports[port_id];

	spa_pod_builder_init(&b, state->params_buffer, sizeof(state->params_buffer));

	switch (index) {
	case 0:
		spa_pod_builder_object(&b, &f[0], 0, this->type.param_alloc_buffers.Buffers,
			PROP(&f[1], this->type.param_alloc_buffers.size, SPA_POD_TYPE_INT,
				state->fmt.fmt.pix.sizeimage),
			PROP(&f[1], this->type.param_alloc_buffers.stride, SPA_POD_TYPE_INT,
				state->fmt.fmt.pix.bytesperline),
			PROP_U_MM(&f[1], this->type.param_alloc_buffers.buffers, SPA_POD_TYPE_INT,
				MAX_BUFFERS, 2, MAX_BUFFERS),
			PROP(&f[1], this->type.param_alloc_buffers.align, SPA_POD_TYPE_INT, 16));
		break;

	case 1:
		spa_pod_builder_object(&b, &f[0], 0, this->type.param_alloc_meta_enable.MetaEnable,
			PROP(&f[1], this->type.param_alloc_meta_enable.type, SPA_POD_TYPE_ID,
				this->type.meta.Header),
			PROP(&f[1], this->type.param_alloc_meta_enable.size, SPA_POD_TYPE_INT,
				sizeof(struct spa_meta_header)));
		break;

	default:
		return SPA_RESULT_NOT_IMPLEMENTED;
	}

	*param = SPA_POD_BUILDER_DEREF(&b, f[0].ref, struct spa_param);

	return SPA_RESULT_OK;
}

static int impl_node_port_set_param(struct spa_node *node,
				    enum spa_direction direction,
				    uint32_t port_id,
				    const struct spa_param *param)
{
	return SPA_RESULT_NOT_IMPLEMENTED;
}

static int impl_node_port_use_buffers(struct spa_node *node,
				      enum spa_direction direction,
				      uint32_t port_id,
				      struct spa_buffer **buffers,
				      uint32_t n_buffers)
{
	struct impl *this;
	struct port *state;
	int res;

	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = SPA_CONTAINER_OF(node, struct impl, node);

	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), SPA_RESULT_INVALID_PORT);

	state = &this->out_ports[port_id];

	if (!state->have_format)
		return SPA_RESULT_NO_FORMAT;

	if (state->n_buffers) {
		spa_v4l2_stream_off(this);
		if ((res = spa_v4l2_clear_buffers(this)) < 0)
			return res;
	}
	if (buffers != NULL) {
		if ((res = spa_v4l2_use_buffers(this, buffers, n_buffers)) < 0)
			return res;
	}
	return SPA_RESULT_OK;
}

static int
impl_node_port_alloc_buffers(struct spa_node *node,
			     enum spa_direction direction,
			     uint32_t port_id,
			     struct spa_param **params,
			     uint32_t n_params,
			     struct spa_buffer **buffers,
			     uint32_t *n_buffers)
{
	struct impl *this;
	struct port *state;
	int res;

	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);
	spa_return_val_if_fail(buffers != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = SPA_CONTAINER_OF(node, struct impl, node);

	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), SPA_RESULT_INVALID_PORT);

	state = &this->out_ports[port_id];

	if (!state->have_format)
		return SPA_RESULT_NO_FORMAT;

	res = spa_v4l2_alloc_buffers(this, params, n_params, buffers, n_buffers);

	return res;
}

static int impl_node_port_set_io(struct spa_node *node,
				 enum spa_direction direction,
				 uint32_t port_id,
				 struct spa_port_io *io)
{
	struct impl *this;

	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = SPA_CONTAINER_OF(node, struct impl, node);

	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), SPA_RESULT_INVALID_PORT);

	this->out_ports[port_id].io = io;

	return SPA_RESULT_OK;
}

static int impl_node_port_reuse_buffer(struct spa_node *node,
				       uint32_t port_id,
				       uint32_t buffer_id)
{
	struct impl *this;
	struct port *state;
	int res;

	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);
	spa_return_val_if_fail(port_id == 0, SPA_RESULT_INVALID_PORT);

	this = SPA_CONTAINER_OF(node, struct impl, node);
	state = &this->out_ports[port_id];

	spa_return_val_if_fail(state->n_buffers > 0, SPA_RESULT_NO_BUFFERS);
	spa_return_val_if_fail(buffer_id < state->n_buffers, SPA_RESULT_INVALID_BUFFER_ID);

	res = spa_v4l2_buffer_recycle(this, buffer_id);

	return res;
}

static int impl_node_port_send_command(struct spa_node *node,
				       enum spa_direction direction,
				       uint32_t port_id,
				       const struct spa_command *command)
{
	struct impl *this;
	int res;

	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = SPA_CONTAINER_OF(node, struct impl, node);

	spa_return_val_if_fail(CHECK_PORT(this, direction, port_id), SPA_RESULT_INVALID_PORT);

	if (SPA_COMMAND_TYPE(command) == this->type.command_node.Pause) {
		res = spa_v4l2_port_set_enabled(this, false);
	} else if (SPA_COMMAND_TYPE(command) == this->type.command_node.Start) {
		res = spa_v4l2_port_set_enabled(this, true);
	} else
		res = SPA_RESULT_NOT_IMPLEMENTED;

	return res;
}

static int impl_node_process_input(struct spa_node *node)
{
	return SPA_RESULT_NOT_IMPLEMENTED;
}

static int impl_node_process_output(struct spa_node *node)
{
	struct impl *this;
	int res = SPA_RESULT_OK;
	struct spa_port_io *io;

	spa_return_val_if_fail(node != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = SPA_CONTAINER_OF(node, struct impl, node);

	io = this->out_ports[0].io;
	spa_return_val_if_fail(io != NULL, SPA_RESULT_WRONG_STATE);

	if (io->status == SPA_RESULT_HAVE_BUFFER)
		return SPA_RESULT_HAVE_BUFFER;

	if (io->buffer_id < this->out_ports[0].n_buffers) {
		res = spa_v4l2_buffer_recycle(this, io->buffer_id);
		io->buffer_id = SPA_ID_INVALID;
	}
	return res;
}

static const struct spa_dict_item info_items[] = {
	{ "media.class", "Video/Source" },
};

static const struct spa_dict info = {
	SPA_N_ELEMENTS(info_items),
	info_items
};

static const struct spa_node impl_node = {
	SPA_VERSION_NODE,
	&info,
	impl_node_get_props,
	impl_node_set_props,
	impl_node_send_command,
	impl_node_set_callbacks,
	impl_node_get_n_ports,
	impl_node_get_port_ids,
	impl_node_add_port,
	impl_node_remove_port,
	impl_node_port_enum_formats,
	impl_node_port_set_format,
	impl_node_port_get_format,
	impl_node_port_get_info,
	impl_node_port_enum_params,
	impl_node_port_set_param,
	impl_node_port_use_buffers,
	impl_node_port_alloc_buffers,
	impl_node_port_set_io,
	impl_node_port_reuse_buffer,
	impl_node_port_send_command,
	impl_node_process_input,
	impl_node_process_output,
};

static int impl_clock_get_props(struct spa_clock *clock, struct spa_props **props)
{
	return SPA_RESULT_NOT_IMPLEMENTED;
}

static int impl_clock_set_props(struct spa_clock *clock, const struct spa_props *props)
{
	return SPA_RESULT_NOT_IMPLEMENTED;
}

static int impl_clock_get_time(struct spa_clock *clock,
			       int32_t *rate,
			       int64_t *ticks,
			       int64_t *monotonic_time)
{
	struct impl *this;
	struct port *state;

	spa_return_val_if_fail(clock != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = SPA_CONTAINER_OF(clock, struct impl, clock);
	state = &this->out_ports[0];

	if (rate)
		*rate = SPA_USEC_PER_SEC;
	if (ticks)
		*ticks = state->last_ticks;
	if (monotonic_time)
		*monotonic_time = state->last_monotonic;

	return SPA_RESULT_OK;
}

static const struct spa_clock impl_clock = {
	SPA_VERSION_CLOCK,
	NULL,
	SPA_CLOCK_STATE_STOPPED,
	impl_clock_get_props,
	impl_clock_set_props,
	impl_clock_get_time,
};

static int impl_get_interface(struct spa_handle *handle, uint32_t interface_id, void **interface)
{
	struct impl *this;

	spa_return_val_if_fail(handle != NULL, SPA_RESULT_INVALID_ARGUMENTS);
	spa_return_val_if_fail(interface != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	this = (struct impl *) handle;

	if (interface_id == this->type.node)
		*interface = &this->node;
	else if (interface_id == this->type.clock)
		*interface = &this->clock;
	else
		return SPA_RESULT_UNKNOWN_INTERFACE;

	return SPA_RESULT_OK;
}

static int impl_clear(struct spa_handle *handle)
{
	return SPA_RESULT_OK;
}

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;
	uint32_t i;
	const char *str;

	spa_return_val_if_fail(factory != NULL, SPA_RESULT_INVALID_ARGUMENTS);
	spa_return_val_if_fail(handle != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	handle->get_interface = impl_get_interface;
	handle->clear = impl_clear, this = (struct impl *) handle;

	for (i = 0; i < n_support; i++) {
		if (strcmp(support[i].type, SPA_TYPE__TypeMap) == 0)
			this->map = support[i].data;
		else if (strcmp(support[i].type, SPA_TYPE__Log) == 0)
			this->log = support[i].data;
		else if (strcmp(support[i].type, SPA_TYPE_LOOP__MainLoop) == 0)
			this->out_ports[0].main_loop = support[i].data;
		else if (strcmp(support[i].type, SPA_TYPE_LOOP__DataLoop) == 0)
			this->out_ports[0].data_loop = support[i].data;
	}
	if (this->map == NULL) {
		spa_log_error(this->log, "a type-map is needed");
		return SPA_RESULT_ERROR;
	}
	if (this->out_ports[0].main_loop == NULL) {
		spa_log_error(this->log, "a main_loop is needed");
		return SPA_RESULT_ERROR;
	}
	if (this->out_ports[0].data_loop == NULL) {
		spa_log_error(this->log, "a data_loop is needed");
		return SPA_RESULT_ERROR;
	}
	init_type(&this->type, this->map);

	this->node = impl_node;
	this->clock = impl_clock;

	reset_props(&this->props);

	this->out_ports[0].log = this->log;
	this->out_ports[0].info.flags = SPA_PORT_INFO_FLAG_LIVE;

	this->out_ports[0].export_buf = true;

	if (info && (str = spa_dict_lookup(info, "device.path"))) {
		strncpy(this->props.device, str, 63);
	}

	return SPA_RESULT_OK;
}

static const struct spa_interface_info impl_interfaces[] = {
	{SPA_TYPE__Node,},
	{SPA_TYPE__Clock,},
};

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, SPA_RESULT_INVALID_ARGUMENTS);
	spa_return_val_if_fail(info != NULL, SPA_RESULT_INVALID_ARGUMENTS);

	if (index >= SPA_N_ELEMENTS(impl_interfaces))
		return SPA_RESULT_ENUM_END;

	*info = &impl_interfaces[index];

	return SPA_RESULT_OK;
}

const struct spa_handle_factory spa_v4l2_source_factory = {
	SPA_VERSION_HANDLE_FACTORY,
	NAME,
	NULL,
	sizeof(struct impl),
	impl_init,
	impl_enum_interface_info,
};