PipeWire 0.3.80
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Exporting and implementing a video sink SPA node, using Core API.

/* PipeWire */
/* SPDX-FileCopyrightText: Copyright © 2018 Wim Taymans */
/* SPDX-License-Identifier: MIT */
Exporting and implementing a video sink SPA node, using \ref api_pw_core.
#include <errno.h>
#include <stdio.h>
#include <sys/mman.h>
#include <spa/param/video/format-utils.h>
#include <spa/node/utils.h>
#include <spa/node/io.h>
#include <spa/pod/filter.h>
#include <spa/debug/pod.h>
#define WIDTH 640
#define HEIGHT 480
#define BPP 3
#include "sdl.h"
#define M_PI_M2 ( M_PI + M_PI )
#define MAX_BUFFERS 64
#define DEFAULT_PARAM 0.1
struct props {
double param;
static void reset_props(struct props *props)
props->param = DEFAULT_PARAM;
struct data {
struct props props;
const char *path;
SDL_Renderer *renderer;
SDL_Window *window;
SDL_Texture *texture;
struct pw_main_loop *loop;
struct pw_context *context;
struct pw_core *core;
struct spa_hook core_listener;
struct spa_node impl_node;
struct spa_hook_list hooks;
struct spa_io_buffers *io;
struct spa_io_sequence *io_notify;
uint32_t io_notify_size;
double param_accum;
uint8_t buffer[1024];
struct spa_video_info_raw format;
int32_t stride;
struct spa_port_info info;
struct spa_param_info params[5];
struct spa_region region;
struct spa_buffer *buffers[MAX_BUFFERS];
uint32_t n_buffers;
static void handle_events(struct data *data)
SDL_Event event;
while (SDL_PollEvent(&event)) {
switch (event.type) {
case SDL_QUIT:
static void update_param(struct data *data)
struct spa_pod_builder b = { 0, };
struct spa_pod_frame f[2];
if (data->io_notify == NULL)
spa_pod_builder_init(&b, data->io_notify, data->io_notify_size);
spa_pod_builder_float(&b, (sin(data->param_accum) * 127.0) + 127.0);
spa_pod_builder_pop(&b, &f[1]);
spa_pod_builder_pop(&b, &f[0]);
data->param_accum += M_PI_M2 / 30.0;
if (data->param_accum >= M_PI_M2)
data->param_accum -= M_PI_M2;
static int impl_send_command(void *object, const struct spa_command *command)
return 0;
static int impl_add_listener(void *object,
struct spa_hook *listener,
const struct spa_node_events *events,
void *data)
struct data *d = object;
struct spa_hook_list save;
uint64_t old;
spa_hook_list_isolate(&d->hooks, &save, listener, events, data);
old = d->info.change_mask;
d->info.change_mask = SPA_PORT_CHANGE_MASK_FLAGS |
spa_node_emit_port_info(&d->hooks, SPA_DIRECTION_INPUT, 0, &d->info);
d->info.change_mask = old;
spa_hook_list_join(&d->hooks, &save);
return 0;
static int impl_set_callbacks(void *object,
const struct spa_node_callbacks *callbacks, void *data)
return 0;
static int impl_set_io(void *object,
uint32_t id, void *data, size_t size)
return 0;
static int impl_port_set_io(void *object,
enum spa_direction direction, uint32_t port_id,
uint32_t id, void *data, size_t size)
struct data *d = object;
switch (id) {
d->io = data;
d->io_notify = data;
d->io_notify_size = size;
return -ENOENT;
return 0;
static int impl_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 data *d = 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;
result.id = id;
result.next = start;
result.index = result.next++;
spa_pod_builder_init(&b, buffer, sizeof(buffer));
switch (id) {
SDL_RendererInfo info;
if (result.index != 0)
return 0;
SDL_GetRendererInfo(d->renderer, &info);
param = sdl_build_formats(&info, &b);
if (result.index != 0 || d->format.format == 0)
return 0;
param = spa_format_video_raw_build(&b, id, &d->format);
if (result.index != 0)
return 0;
SPA_PARAM_BUFFERS_size, SPA_POD_Int(d->stride * d->format.size.height),
switch (result.index) {
case 0:
case 1:
return 0;
switch (result.index) {
case 0:
case 1:
SPA_PARAM_IO_size, SPA_POD_Int(sizeof(struct spa_io_sequence) + 1024));
return 0;
return -ENOENT;
if (spa_pod_filter(&b, &result.param, param, filter) < 0)
goto next;
spa_node_emit_result(&d->hooks, seq, 0, SPA_RESULT_TYPE_NODE_PARAMS, &result);
if (++count != num)
goto next;
return 0;
static int port_set_format(void *object,
enum spa_direction direction, uint32_t port_id,
uint32_t flags, const struct spa_pod *format)
struct data *d = object;
Uint32 sdl_format;
void *dest;
if (format == NULL) {
d->texture = NULL;
} else {
spa_debug_format(0, NULL, format);
spa_format_video_raw_parse(format, &d->format);
sdl_format = id_to_sdl_format(d->format.format);
if (sdl_format == SDL_PIXELFORMAT_UNKNOWN)
return -EINVAL;
if (d->format.size.width == 0 ||
d->format.size.height == 0)
return -EINVAL;
d->texture = SDL_CreateTexture(d->renderer,
SDL_LockTexture(d->texture, NULL, &dest, &d->stride);
d->info.change_mask = SPA_PORT_CHANGE_MASK_PARAMS;
if (format) {
} else {
d->params[4] = SPA_PARAM_INFO(SPA_PARAM_Buffers, 0);
spa_node_emit_port_info(&d->hooks, direction, port_id, &d->info);
d->info.change_mask = 0;
return 0;
static int impl_port_set_param(void *object,
enum spa_direction direction, uint32_t port_id,
uint32_t id, uint32_t flags,
const struct spa_pod *param)
if (id == SPA_PARAM_Format) {
return port_set_format(object, direction, port_id, flags, param);
return -ENOENT;
static int impl_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 data *d = object;
uint32_t i;
if (n_buffers > MAX_BUFFERS)
return -ENOSPC;
for (i = 0; i < n_buffers; i++)
d->buffers[i] = buffers[i];
d->n_buffers = n_buffers;
return 0;
static int do_render(struct spa_loop *loop, bool async, uint32_t seq,
const void *_data, size_t size, void *user_data)
struct data *d = user_data;
const struct spa_buffer *buf = *(struct spa_buffer**)_data;
uint8_t *map;
void *sdata, *ddata;
int sstride, dstride, ostride;
uint32_t i;
uint8_t *src, *dst;
struct spa_meta *m;
struct spa_meta_region *r;
if (buf->datas[0].type == SPA_DATA_MemFd ||
buf->datas[0].type == SPA_DATA_DmaBuf) {
map = mmap(NULL, buf->datas[0].maxsize + buf->datas[0].mapoffset, PROT_READ,
MAP_PRIVATE, buf->datas[0].fd, 0);
sdata = SPA_PTROFF(map, buf->datas[0].mapoffset, uint8_t);
} else if (buf->datas[0].type == SPA_DATA_MemPtr) {
map = NULL;
sdata = buf->datas[0].data;
} else
return -EINVAL;
if (SDL_LockTexture(d->texture, NULL, &ddata, &dstride) < 0) {
fprintf(stderr, "Couldn't lock texture: %s\n", SDL_GetError());
return -EIO;
if (memcmp(&r->region, &d->region, sizeof(struct spa_region)) == 0)
d->region = r->region;
fprintf(stderr, "region %dx%d->%dx%d\n",
sstride = buf->datas[0].chunk->stride;
ostride = SPA_MIN(sstride, dstride);
src = sdata;
dst = ddata;
for (i = 0; i < d->format.size.height; i++) {
memcpy(dst, src, ostride);
src += sstride;
dst += dstride;
SDL_RenderCopy(d->renderer, d->texture, NULL, NULL);
if (map)
munmap(map, buf->datas[0].maxsize + buf->datas[0].mapoffset);
return 0;
static int impl_node_process(void *object)
struct data *d = object;
struct spa_buffer *buf;
int res;
if (d->io->status != SPA_STATUS_HAVE_DATA)
if (d->io->buffer_id >= d->n_buffers)
buf = d->buffers[d->io->buffer_id];
if ((res = pw_loop_invoke(pw_main_loop_get_loop(d->loop), do_render,
SPA_ID_INVALID, &buf, sizeof(struct spa_buffer *),
false, d)) < 0)
return res;
return d->io->status = SPA_STATUS_NEED_DATA;
static const struct spa_node_methods impl_node = {
.add_listener = impl_add_listener,
.set_callbacks = impl_set_callbacks,
.set_io = impl_set_io,
.send_command = impl_send_command,
.port_set_io = impl_port_set_io,
.port_enum_params = impl_port_enum_params,
.port_set_param = impl_port_set_param,
.port_use_buffers = impl_port_use_buffers,
.process = impl_node_process,
static void make_node(struct data *data)
struct pw_properties *props;
if (data->path)
pw_properties_set(props, PW_KEY_MEDIA_CLASS, "Stream/Input/Video");
data->impl_node.iface = SPA_INTERFACE_INIT(
&impl_node, data);
&props->dict, &data->impl_node, 0);
static void set_permissions(struct data *data)
/* an example, set specific permissions on one object, this is the
* core object. */
/* remove WX from all other objects */
static void on_core_error(void *data, uint32_t id, int seq, int res, const char *message)
struct data *d = 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)
static const struct pw_core_events core_events = {
.error = on_core_error,
int main(int argc, char *argv[])
struct data data = { 0, };
pw_init(&argc, &argv);
data.loop = pw_main_loop_new(NULL);
data.context = pw_context_new(pw_main_loop_get_loop(data.loop), NULL, 0);
data.path = argc > 1 ? argv[1] : NULL;
data.info = SPA_PORT_INFO_INIT();
data.info.change_mask = SPA_PORT_CHANGE_MASK_FLAGS;
data.info.flags = 0;
data.info.change_mask |= SPA_PORT_CHANGE_MASK_PARAMS;
data.info.params = data.params;
data.info.n_params = 5;
if (SDL_Init(SDL_INIT_VIDEO) < 0) {
printf("can't initialize SDL: %s\n", SDL_GetError());
return -1;
if (SDL_CreateWindowAndRenderer
(WIDTH, HEIGHT, SDL_WINDOW_RESIZABLE, &data.window, &data.renderer)) {
printf("can't create window: %s\n", SDL_GetError());
return -1;
data.core = pw_context_connect(data.context, NULL, 0);
if (data.core == NULL) {
printf("can't connect: %m\n");
return -1;
pw_core_add_listener(data.core, &data.core_listener, &core_events, &data);
return 0;
#define pw_client_update_permissions(c,...)
Manage the permissions of the global objects for this client.
Definition: client.h:196
void pw_context_destroy(struct pw_context *context)
destroy a context object, all resources except the main_loop will be destroyed
Definition: context.c:384
struct pw_context * pw_context_new(struct pw_loop *main_loop, struct pw_properties *props, size_t user_data_size)
Make a new context object for a given main_loop.
Definition: context.c:172
#define PW_ID_CORE
default ID for the core object after connect
Definition: core.h:62
struct pw_core * pw_context_connect(struct pw_context *context, struct pw_properties *properties, size_t user_data_size)
Connect to a PipeWire instance.
Definition: core.c:390
#define PW_ID_ANY
Definition: core.h:66
struct pw_client * pw_core_get_client(struct pw_core *core)
Get the client proxy of the connected core.
Definition: core.c:253
struct pw_proxy * pw_core_export(struct pw_core *core, const char *type, const struct spa_dict *props, void *object, size_t user_data_size)
Export an object into the PipeWire instance associated with core.
Definition: core.c:265
#define pw_core_add_listener(c,...)
Definition: core.h:364
Definition: core.h:128
Definition: src/pipewire/keys.h:431
node wants to be automatically connected to a compatible node
Definition: src/pipewire/keys.h:201
a target object to link to.
Definition: src/pipewire/keys.h:496
Role: Movie, Music, Camera, Screen, Communication, Game, Notification, DSP, Production,...
Definition: src/pipewire/keys.h:437
Media Category: Playback, Capture, Duplex, Monitor, Manager.
Definition: src/pipewire/keys.h:434
class Ex: "Video/Source"
Definition: src/pipewire/keys.h:442
#define pw_log_error(...)
Definition: src/pipewire/log.h:142
#define pw_loop_invoke(l,...)
Definition: src/pipewire/loop.h:47
int pw_main_loop_quit(struct pw_main_loop *loop)
Quit a main loop.
Definition: main-loop.c:105
void pw_main_loop_destroy(struct pw_main_loop *loop)
Destroy a loop.
Definition: main-loop.c:70
int pw_main_loop_run(struct pw_main_loop *loop)
Run a main loop.
Definition: main-loop.c:119
struct pw_main_loop * pw_main_loop_new(const struct spa_dict *props)
Create a new main loop.
Definition: main-loop.c:60
struct pw_loop * pw_main_loop_get_loop(struct pw_main_loop *loop)
Get the loop implementation.
Definition: main-loop.c:93
#define PW_PERM_X
methods can be called on the object.
Definition: permission.h:36
#define PW_PERM_R
object can be seen and events can be received
Definition: permission.h:32
#define PW_PERMISSION_INIT(id, p)
Definition: permission.h:75
void pw_init(int *argc, char **argv[])
Initialize PipeWire.
Definition: pipewire.c:555
void pw_properties_free(struct pw_properties *properties)
Free a properties object.
Definition: properties.c:350
struct pw_properties * pw_properties_new(const char *key,...) 1
Make a new properties object.
Definition: properties.c:84
int pw_properties_set(struct pw_properties *properties, const char *key, const char *value)
Set a property value.
Definition: properties.c:421
#define spa_meta_region_is_valid
Definition: meta.h:96
static struct spa_meta * spa_buffer_find_meta(const struct spa_buffer *b, uint32_t type)
Find metadata in a buffer.
Definition: buffer/buffer.h:98
#define spa_meta_for_each(pos, meta)
iterate all the items in a metadata
Definition: meta.h:99
@ SPA_META_VideoDamage
array of struct spa_meta_region with damage, where an invalid entry or end-of-array marks the end.
Definition: meta.h:29
@ SPA_META_Header
struct spa_meta_header
Definition: meta.h:27
generic fd, mmap to get to memory
Definition: buffer/buffer.h:35
pointer to memory, the data field in struct spa_data is set.
Definition: buffer/buffer.h:33
fd to dmabuf memory
Definition: buffer/buffer.h:36
@ SPA_CONTROL_Properties
data contains a SPA_TYPE_OBJECT_Props
Definition: spa/include/spa/control/control.h:32
static int spa_debug_format(int indent, const struct spa_type_info *info, const struct spa_pod *format)
Definition: debug/format.h:206
static void spa_hook_list_join(struct spa_hook_list *list, struct spa_hook_list *save)
Definition: hook.h:422
static void spa_hook_list_init(struct spa_hook_list *list)
Initialize a hook list to the empty list.
Definition: hook.h:360
static void spa_hook_list_isolate(struct spa_hook_list *list, struct spa_hook_list *save, struct spa_hook *hook, const void *funcs, void *data)
Definition: hook.h:408
#define SPA_INTERFACE_INIT(_type, _version, _funcs, _data)
Initialize a spa_interface.
Definition: hook.h:157
Definition: spa/include/spa/node/node.h:95
#define spa_node_emit_port_info(hooks,...)
Definition: spa/include/spa/node/utils.h:118
Definition: spa/include/spa/node/node.h:139
Definition: io.h:84
Definition: spa/include/spa/node/node.h:37
Definition: io.h:82
Definition: spa/include/spa/node/node.h:40
Definition: spa/include/spa/node/node.h:101
Definition: spa/include/spa/node/node.h:144
#define spa_node_emit_result(hooks,...)
Definition: spa/include/spa/node/utils.h:119
Definition: spa/include/spa/node/node.h:331
@ SPA_IO_Notify
area for notify messages, struct spa_io_sequence
Definition: io.h:43
@ SPA_IO_Buffers
area to exchange buffers, struct spa_io_buffers
Definition: io.h:38
Definition: param.h:59
Definition: param.h:57
Definition: param.h:61
static struct spa_pod * spa_format_video_raw_build(struct spa_pod_builder *builder, uint32_t id, struct spa_video_info_raw *info)
Definition: video/raw-utils.h:58
static int spa_format_video_raw_parse(const struct spa_pod *format, struct spa_video_info_raw *info)
Definition: video/raw-utils.h:27
#define SPA_PARAM_INFO(id, flags)
Definition: param.h:71
@ SPA_PROP_contrast
Definition: props.h:104
the expected maximum size the meta (Int)
Definition: spa/include/spa/param/buffers.h:39
the metadata, one of enum spa_meta_type (Id enum spa_meta_type)
Definition: spa/include/spa/param/buffers.h:38
@ SPA_PARAM_Format
configured format as SPA_TYPE_OBJECT_Format
Definition: param.h:34
allowed metadata for buffers as SPA_TYPE_OBJECT_ParamMeta
Definition: param.h:36
configurable IO areas as SPA_TYPE_OBJECT_ParamIO
Definition: param.h:37
@ SPA_PARAM_EnumFormat
available formats as SPA_TYPE_OBJECT_Format
Definition: param.h:33
@ SPA_PARAM_Buffers
buffer configurations as SPA_TYPE_OBJECT_ParamBuffers
Definition: param.h:35
type ID, uniquely identifies the io area (Id enum spa_io_type)
Definition: spa/include/spa/param/buffers.h:45
size of the io area (Int)
Definition: spa/include/spa/param/buffers.h:46
size of a data block memory (Int)
Definition: spa/include/spa/param/buffers.h:29
stride of data block memory (Int)
Definition: spa/include/spa/param/buffers.h:30
number of data blocks per buffer (Int)
Definition: spa/include/spa/param/buffers.h:28
number of buffers (Int)
Definition: spa/include/spa/param/buffers.h:27
static int spa_pod_builder_prop(struct spa_pod_builder *builder, uint32_t key, uint32_t flags)
Definition: builder.h:450
static int spa_pod_builder_float(struct spa_pod_builder *builder, float val)
Definition: builder.h:265
#define SPA_POD_CHOICE_RANGE_Int(def, min, max)
Definition: vararg.h:58
static int spa_pod_builder_push_sequence(struct spa_pod_builder *builder, struct spa_pod_frame *frame, uint32_t unit)
Definition: builder.h:460
#define SPA_POD_Id(val)
Definition: vararg.h:49
static void * spa_pod_builder_pop(struct spa_pod_builder *builder, struct spa_pod_frame *frame)
Definition: builder.h:168
static int spa_pod_builder_control(struct spa_pod_builder *builder, uint32_t offset, uint32_t type)
Definition: builder.h:471
#define spa_pod_builder_add_object(b, type, id,...)
Definition: builder.h:659
static void spa_pod_builder_init(struct spa_pod_builder *builder, void *data, uint32_t size)
Definition: builder.h:87
static int spa_pod_builder_push_object(struct spa_pod_builder *builder, struct spa_pod_frame *frame, uint32_t type, uint32_t id)
Definition: builder.h:435
#define SPA_POD_Int(val)
Definition: vararg.h:54
static int spa_pod_filter(struct spa_pod_builder *b, struct spa_pod **result, const struct spa_pod *pod, const struct spa_pod *filter)
Definition: spa/include/spa/pod/filter.h:431
#define spa_strerror(err)
Definition: result.h:49
@ SPA_TYPE_OBJECT_ParamBuffers
Definition: spa/include/spa/utils/type.h:77
Definition: spa/include/spa/utils/type.h:79
Definition: spa/include/spa/utils/type.h:75
Definition: spa/include/spa/utils/type.h:78
#define SPA_MIN(a, b)
Definition: defs.h:151
#define spa_zero(x)
Definition: defs.h:417
Definition: defs.h:228
Definition: defs.h:92
#define SPA_PTROFF(ptr_, offset_, type_)
Return the address (buffer + offset) as pointer of type.
Definition: defs.h:194
Definition: defs.h:93
Core events.
Definition: core.h:126
A main loop object.
Definition: permission.h:69
uint32_t permissions
bitmask of above permissions
Definition: permission.h:71
Definition: properties.h:33
struct spa_dict dict
dictionary of key/values
Definition: properties.h:34
A Buffer.
Definition: buffer/buffer.h:90
struct spa_data * datas
array of data members
Definition: buffer/buffer.h:94
int32_t stride
stride of valid data
Definition: buffer/buffer.h:49
Definition: pod/command.h:29
struct spa_chunk * chunk
valid chunk of memory
Definition: buffer/buffer.h:86
int64_t fd
optional fd for data
Definition: buffer/buffer.h:82
uint32_t mapoffset
offset to map fd at
Definition: buffer/buffer.h:83
void * data
optional data pointer
Definition: buffer/buffer.h:85
uint32_t maxsize
max size of data
Definition: buffer/buffer.h:84
uint32_t type
memory type, one of enum spa_data_type, when allocating memory, the type contains a bitmask of allowe...
Definition: buffer/buffer.h:63
A list of hooks.
Definition: hook.h:339
A hook, contains the structure with functions and the data passed to the functions.
Definition: hook.h:350
IO area to exchange buffers.
Definition: io.h:78
control stream, io area for SPA_IO_Control and SPA_IO_Notify
Definition: io.h:170
Definition: spa/include/spa/support/loop.h:36
Describes essential buffer header metadata such as flags and timestamps.
Definition: meta.h:67
metadata structure for Region or an array of these for RegionArray
Definition: meta.h:89
struct spa_region region
Definition: meta.h:90
A metadata element.
Definition: meta.h:47
Node callbacks.
Definition: spa/include/spa/node/node.h:232
events from the spa_node.
Definition: spa/include/spa/node/node.h:176
Node methods.
Definition: spa/include/spa/node/node.h:327
Definition: spa/include/spa/node/node.h:41
information about a parameter
Definition: param.h:51
Definition: builder.h:53
Definition: iter.h:27
Definition: pod/pod.h:43
int32_t y
Definition: defs.h:111
int32_t x
Definition: defs.h:110
Port information structure.
Definition: spa/include/spa/node/node.h:93
uint32_t width
Definition: defs.h:103
uint32_t height
Definition: defs.h:104
Definition: defs.h:116
struct spa_point position
Definition: defs.h:117
struct spa_rectangle size
Definition: defs.h:118
the result of enum_params or port_enum_params.
Definition: spa/include/spa/node/node.h:152
struct spa_pod * param
the result param
Definition: spa/include/spa/node/node.h:156
uint32_t next
next index of iteration
Definition: spa/include/spa/node/node.h:155
uint32_t id
id of parameter
Definition: spa/include/spa/node/node.h:153
Definition: video/raw.h:176