PipeWire 0.3.80
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Allocating buffer memory and sending fds to the server.

/* PipeWire */
/* SPDX-FileCopyrightText: Copyright © 2018 Wim Taymans */
/* SPDX-License-Identifier: MIT */
Allocating buffer memory and sending fds to the server.
#include "config.h"
#include <stdio.h>
#include <errno.h>
#include <signal.h>
#include <math.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <spa/param/video/format-utils.h>
#define BPP 3
#define CURSOR_WIDTH 64
#define CURSOR_HEIGHT 64
#define CURSOR_BPP 4
#define MAX_BUFFERS 64
#define M_PI_M2 ( M_PI + M_PI )
struct data {
struct pw_thread_loop *loop;
struct spa_source *timer;
struct pw_stream *stream;
struct spa_hook stream_listener;
struct spa_video_info_raw format;
int32_t stride;
int counter;
uint32_t seq;
double crop;
double accumulator;
static void draw_elipse(uint32_t *dst, int width, int height, uint32_t color)
int i, j, r1, r2, r12, r22, r122;
r1 = width/2;
r12 = r1 * r1;
r2 = height/2;
r22 = r2 * r2;
r122 = r12 * r22;
for (i = -r2; i < r2; i++) {
for (j = -r1; j < r1; j++) {
dst[(i + r2)*width+(j+r1)] =
(i * i * r12 + j * j * r22 <= r122) ? color : 0x00000000;
/* called when we should push a new buffer in the queue */
static void on_process(void *userdata)
struct data *data = userdata;
struct pw_buffer *b;
struct spa_buffer *buf;
uint32_t i, j;
uint8_t *p;
struct spa_meta *m;
struct spa_meta_header *h;
struct spa_meta_region *mc;
struct spa_meta_cursor *mcs;
if ((b = pw_stream_dequeue_buffer(data->stream)) == NULL) {
pw_log_warn("out of buffers: %m");
buf = b->buffer;
if ((p = buf->datas[0].data) == NULL)
if ((h = spa_buffer_find_meta_data(buf, SPA_META_Header, sizeof(*h)))) {
#if 0
struct timespec now;
clock_gettime(CLOCK_MONOTONIC, &now);
h->pts = -1;
h->flags = 0;
h->seq = data->seq++;
h->dts_offset = 0;
if (spa_meta_check(r, m)) {
r->region.size = data->format.size;
if (spa_meta_check(r, m))
r->region = SPA_REGION(0,0,0,0);
if ((mc = spa_buffer_find_meta_data(buf, SPA_META_VideoCrop, sizeof(*mc)))) {
data->crop = (sin(data->accumulator) + 1.0) * 32.0;
mc->region.position.x = data->crop;
mc->region.position.y = data->crop;
mc->region.size.width = data->format.size.width - data->crop*2;
mc->region.size.height = data->format.size.height - data->crop*2;
if ((mcs = spa_buffer_find_meta_data(buf, SPA_META_Cursor, sizeof(*mcs)))) {
struct spa_meta_bitmap *mb;
uint32_t *bitmap, color;
mcs->id = 1;
mcs->position.x = (sin(data->accumulator) + 1.0) * 160.0 + 80;
mcs->position.y = (cos(data->accumulator) + 1.0) * 100.0 + 50;
mcs->hotspot.x = 0;
mcs->hotspot.y = 0;
mcs->bitmap_offset = sizeof(struct spa_meta_cursor);
mb = SPA_PTROFF(mcs, mcs->bitmap_offset, struct spa_meta_bitmap);
mb->size.width = CURSOR_WIDTH;
mb->size.height = CURSOR_HEIGHT;
mb->offset = sizeof(struct spa_meta_bitmap);
bitmap = SPA_PTROFF(mb, mb->offset, uint32_t);
color = (cos(data->accumulator) + 1.0) * (1 << 23);
color |= 0xff000000;
draw_elipse(bitmap, mb->size.width, mb->size.height, color);
for (i = 0; i < data->format.size.height; i++) {
for (j = 0; j < data->format.size.width * BPP; j++) {
p[j] = data->counter + j * i;
p += data->stride;
data->counter += 13;
data->accumulator += M_PI_M2 / 50.0;
if (data->accumulator >= M_PI_M2)
data->accumulator -= M_PI_M2;
buf->datas[0].chunk->offset = 0;
buf->datas[0].chunk->size = data->format.size.height * data->stride;
buf->datas[0].chunk->stride = data->stride;
pw_stream_queue_buffer(data->stream, b);
/* trigger the graph when we are a driver */
static void on_timeout(void *userdata, uint64_t expirations)
struct data *data = userdata;
/* when the stream is STREAMING, start the timer at 40ms intervals
* to produce and push a frame. In other states we PAUSE the timer. */
static void on_stream_state_changed(void *_data, enum pw_stream_state old, enum pw_stream_state state,
const char *error)
struct data *data = _data;
printf("stream state: \"%s\"\n", pw_stream_state_as_string(state));
switch (state) {
printf("node id: %d\n", pw_stream_get_node_id(data->stream));
data->timer, NULL, NULL, false);
struct timespec timeout, interval;
timeout.tv_sec = 0;
timeout.tv_nsec = 1;
interval.tv_sec = 0;
interval.tv_nsec = 40 * SPA_NSEC_PER_MSEC;
if (pw_stream_is_driving(data->stream))
data->timer, &timeout, &interval, false);
/* we set the PW_STREAM_FLAG_ALLOC_BUFFERS flag when connecting so we need
* to provide buffer memory. */
static void on_stream_add_buffer(void *_data, struct pw_buffer *buffer)
struct data *data = _data;
struct spa_buffer *buf = buffer->buffer;
struct spa_data *d;
unsigned int seals;
pw_log_info("add buffer %p", buffer);
d = buf->datas;
if ((d[0].type & (1<<SPA_DATA_MemFd)) == 0) {
pw_log_error("unsupported data type %08x", d[0].type);
/* create the memfd on the buffer, set the type and flags */
d[0].fd = memfd_create("video-src-memfd", MFD_CLOEXEC | MFD_ALLOW_SEALING);
d[0].fd = -1;
if (d[0].fd == -1) {
pw_log_error("can't create memfd: %m");
d[0].mapoffset = 0;
d[0].maxsize = data->stride * data->format.size.height;
/* truncate to the right size before we set seals */
if (ftruncate(d[0].fd, d[0].maxsize) < 0) {
pw_log_error("can't truncate to %d: %m", d[0].maxsize);
/* not enforced yet but server might require SEAL_SHRINK later */
if (fcntl(d[0].fd, F_ADD_SEALS, seals) == -1) {
pw_log_warn("Failed to add seals: %m");
/* now mmap so we can write to it in the process function above */
d[0].data = mmap(NULL, d[0].maxsize, PROT_READ|PROT_WRITE,
MAP_SHARED, d[0].fd, d[0].mapoffset);
if (d[0].data == MAP_FAILED) {
pw_log_error("can't mmap memory: %m");
/* close the memfd we set on the buffers here */
static void on_stream_remove_buffer(void *_data, struct pw_buffer *buffer)
struct spa_buffer *buf = buffer->buffer;
struct spa_data *d;
d = buf->datas;
pw_log_info("remove buffer %p", buffer);
munmap(d[0].data, d[0].maxsize);
/* Be notified when the stream param changes. We're only looking at the
* format param.
* We are now supposed to call pw_stream_update_params() with success or
* failure, depending on if we can support the format. Because we gave
* a list of supported formats, this should be ok.
* As part of pw_stream_update_params() we can provide parameters that
* will control the buffer memory allocation. This includes the metadata
* that we would like on our buffer, the size, alignment, etc.
static void
on_stream_param_changed(void *_data, uint32_t id, const struct spa_pod *param)
struct data *data = _data;
struct pw_stream *stream = data->stream;
uint8_t params_buffer[1024];
struct spa_pod_builder b = SPA_POD_BUILDER_INIT(params_buffer, sizeof(params_buffer));
const struct spa_pod *params[5];
if (param == NULL || id != SPA_PARAM_Format)
spa_format_video_raw_parse(param, &data->format);
data->stride = SPA_ROUND_UP_N(data->format.size.width * BPP, 4);
SPA_PARAM_BUFFERS_size, SPA_POD_Int(data->stride * data->format.size.height),
sizeof(struct spa_meta_region) * 16,
sizeof(struct spa_meta_region) * 1,
sizeof(struct spa_meta_region) * 16));
#define CURSOR_META_SIZE(w,h) (sizeof(struct spa_meta_cursor) + \
sizeof(struct spa_meta_bitmap) + w * h * CURSOR_BPP)
pw_stream_update_params(stream, params, 5);
static const struct pw_stream_events stream_events = {
.process = on_process,
.state_changed = on_stream_state_changed,
.param_changed = on_stream_param_changed,
.add_buffer = on_stream_add_buffer,
.remove_buffer = on_stream_remove_buffer,
static void do_quit(void *userdata, int signal_number)
struct data *data = userdata;
pw_thread_loop_signal(data->loop, false);
int main(int argc, char *argv[])
struct data data = { 0, };
const struct spa_pod *params[1];
uint8_t buffer[1024];
struct spa_pod_builder b = SPA_POD_BUILDER_INIT(buffer, sizeof(buffer));
pw_init(&argc, &argv);
/* create a thread loop and start it */
data.loop = pw_thread_loop_new("video-src-alloc", NULL);
/* take the lock around all PipeWire functions. In callbacks, the lock
* is already taken for you but it's ok to lock again because the lock is
* recursive */
/* install some handlers to exit nicely */
/* start after the signal handlers are set */
/* create a simple stream, the simple stream manages the core
* object for you if you don't want to deal with them.
* We're making a new video provider. We need to set the media-class
* property.
* Pass your events and a user_data pointer as the last arguments. This
* will inform you about the stream state. The most important event
* you need to listen to is the process event where you need to provide
* the data.
PW_KEY_MEDIA_CLASS, "Video/Source",
/* make a timer to schedule our frames */
data.timer = pw_loop_add_timer(pw_thread_loop_get_loop(data.loop), on_timeout, &data);
/* build the extra parameter for the connection. Here we make an
* EnumFormat parameter which lists the possible formats we can provide.
* The server will select a format that matches and informs us about this
* in the stream param_changed event.
&SPA_RECTANGLE(320, 240),
&SPA_RECTANGLE(4096, 4096)),
/* now connect the stream, we need a direction (input/output),
* an optional target node to connect to, some flags and parameters.
* Here we pass PW_STREAM_FLAG_ALLOC_BUFFERS. We should in the
* add_buffer callback configure the buffer memory. This should be
* fd backed memory (memfd, dma-buf, ...) that can be shared with
* the server. */
params, 1);
/* unlock, run the loop and wait, this will trigger the callbacks */
/* unlock before stop */
/* destroy after dependent objects are destroyed */
return 0;
#define PW_ID_ANY
Definition: core.h:66
class Ex: "Video/Source"
Definition: src/pipewire/keys.h:442
#define pw_log_trace(...)
Definition: src/pipewire/log.h:146
#define pw_log_warn(...)
Definition: src/pipewire/log.h:143
#define pw_log_error(...)
Definition: src/pipewire/log.h:142
#define pw_log_info(...)
Definition: src/pipewire/log.h:144
#define pw_loop_update_timer(l,...)
Definition: src/pipewire/loop.h:62
#define pw_loop_add_timer(l,...)
Definition: src/pipewire/loop.h:61
#define pw_loop_add_signal(l,...)
Definition: src/pipewire/loop.h:63
void pw_init(int *argc, char **argv[])
Initialize PipeWire.
Definition: pipewire.c:555
void pw_deinit(void)
Deinitialize PipeWire.
Definition: pipewire.c:668
Definition: port.h:50
struct pw_properties * pw_properties_new(const char *key,...) 1
Make a new properties object.
Definition: properties.c:84
int int pw_stream_update_params(struct pw_stream *stream, const struct spa_pod **params, uint32_t n_params)
Update the param exposed on the stream.
Definition: stream.c:2187
int pw_stream_connect(struct pw_stream *stream, enum pw_direction direction, uint32_t target_id, enum pw_stream_flags flags, const struct spa_pod **params, uint32_t n_params)
Connect a stream for input or output on port_path.
Definition: stream.c:1882
struct pw_buffer * pw_stream_dequeue_buffer(struct pw_stream *stream)
Get a buffer that can be filled for playback streams or consumed for capture streams.
Definition: stream.c:2385
uint32_t pw_stream_get_node_id(struct pw_stream *stream)
Get the node ID of the stream.
Definition: stream.c:2147
bool pw_stream_is_driving(struct pw_stream *stream)
Check if the stream is driving.
Definition: stream.c:2494
const char * pw_stream_state_as_string(enum pw_stream_state state)
Convert a stream state to a readable string.
Definition: stream.c:1625
The state of a stream.
Definition: stream.h:184
int pw_stream_trigger_process(struct pw_stream *stream)
Trigger a push/pull on the stream.
Definition: stream.c:2531
int pw_stream_queue_buffer(struct pw_stream *stream, struct pw_buffer *buffer)
Submit a buffer for playback or recycle a buffer for capture.
Definition: stream.c:2413
struct pw_stream * pw_stream_new_simple(struct pw_loop *loop, const char *name, struct pw_properties *props, const struct pw_stream_events *events, void *data)
Definition: stream.c:1581
Definition: stream.h:330
void pw_stream_destroy(struct pw_stream *stream)
Destroy a stream.
Definition: stream.c:1675
be a driver
Definition: stream.h:379
the application will allocate buffer memory.
Definition: stream.h:388
Definition: stream.h:188
Definition: stream.h:189
void pw_thread_loop_unlock(struct pw_thread_loop *loop)
Unlock the loop.
Definition: thread-loop.c:381
int pw_thread_loop_start(struct pw_thread_loop *loop)
Start the thread loop.
Definition: thread-loop.c:316
struct pw_loop * pw_thread_loop_get_loop(struct pw_thread_loop *loop)
Get the loop implementation of the thread loop.
Definition: thread-loop.c:277
void pw_thread_loop_destroy(struct pw_thread_loop *loop)
Destroy a thread loop.
Definition: thread-loop.c:243
void pw_thread_loop_stop(struct pw_thread_loop *loop)
Stop the thread loop.
Definition: thread-loop.c:349
void pw_thread_loop_lock(struct pw_thread_loop *loop)
Lock the loop.
Definition: thread-loop.c:369
struct pw_thread_loop * pw_thread_loop_new(const char *name, const struct spa_dict *props)
Make a new thread loop with the given name and optional properties.
Definition: thread-loop.c:214
void pw_thread_loop_wait(struct pw_thread_loop *loop)
Release the lock and wait until some thread calls pw_thread_loop_signal.
Definition: thread-loop.c:421
void pw_thread_loop_signal(struct pw_thread_loop *loop, bool wait_for_accept)
Signal all threads waiting with pw_thread_loop_wait.
Definition: thread-loop.c:397
Definition: buffer/buffer.h:80
#define spa_meta_first
Definition: meta.h:56
static void * spa_buffer_find_meta_data(const struct spa_buffer *b, uint32_t type, size_t size)
Definition: buffer/buffer.h:109
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_check(p, m)
Definition: meta.h:61
@ 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_Cursor
struct spa_meta_cursor
Definition: meta.h:31
@ SPA_META_VideoCrop
struct spa_meta_region with cropping data
Definition: meta.h:28
@ SPA_META_Header
struct spa_meta_header
Definition: meta.h:27
generic fd, mmap to get to memory
Definition: buffer/buffer.h:35
static int spa_format_video_raw_parse(const struct spa_pod *format, struct spa_video_info_raw *info)
Definition: video/raw-utils.h:27
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
Definition: param/format.h:28
@ 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
@ 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
@ SPA_FORMAT_VIDEO_framerate
frame rate (Fraction)
Definition: param/format.h:124
@ SPA_FORMAT_mediaType
media type (Id enum spa_media_type)
Definition: param/format.h:93
size (Rectangle)
Definition: param/format.h:123
video format (Id enum spa_video_format)
Definition: param/format.h:120
@ SPA_FORMAT_mediaSubtype
media subtype (Id enum spa_media_subtype)
Definition: param/format.h:94
Definition: param/format.h:38
Definition: video/raw.h:58
Definition: video/raw.h:60
possible memory types (Int, mask of enum spa_data_type)
Definition: spa/include/spa/param/buffers.h:32
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
#define SPA_POD_Fraction(val)
Definition: vararg.h:111
#define SPA_POD_CHOICE_RANGE_Int(def, min, max)
Definition: vararg.h:58
#define SPA_POD_Id(val)
Definition: vararg.h:49
#define SPA_POD_BUILDER_INIT(buffer, size)
Definition: builder.h:62
#define SPA_POD_CHOICE_RANGE_Rectangle(def, min, max)
Definition: vararg.h:106
#define spa_pod_builder_add_object(b, type, id,...)
Definition: builder.h:659
#define SPA_POD_Int(val)
Definition: vararg.h:54
#define SPA_POD_CHOICE_FLAGS_Int(flags)
Definition: vararg.h:62
@ SPA_TYPE_OBJECT_ParamBuffers
Definition: spa/include/spa/utils/type.h:77
Definition: spa/include/spa/utils/type.h:78
Definition: spa/include/spa/utils/type.h:76
#define SPA_ROUND_UP_N(num, align)
Definition: defs.h:320
#define SPA_FRACTION(num, denom)
Definition: defs.h:122
Definition: defs.h:233
#define SPA_REGION(x, y, width, height)
Definition: defs.h:115
Definition: defs.h:244
#define SPA_PTROFF(ptr_, offset_, type_)
Return the address (buffer + offset) as pointer of type.
Definition: defs.h:194
#define SPA_POINT(x, y)
Definition: defs.h:108
#define SPA_RECTANGLE(width, height)
Definition: defs.h:101
a buffer structure obtained from pw_stream_dequeue_buffer().
Definition: stream.h:194
struct spa_buffer * buffer
the spa buffer
Definition: stream.h:195
Events for a stream.
Definition: stream.h:328
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
uint32_t size
size of valid data.
Definition: buffer/buffer.h:47
uint32_t offset
offset of valid data.
Definition: buffer/buffer.h:44
Data for a buffer this stays constant for a buffer.
Definition: buffer/buffer.h:62
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
uint32_t flags
data flags
Definition: buffer/buffer.h:81
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 hook, contains the structure with functions and the data passed to the functions.
Definition: hook.h:350
Bitmap information.
Definition: meta.h:113
struct spa_rectangle size
width and height of bitmap
Definition: meta.h:117
uint32_t format
bitmap video format, one of enum spa_video_format.
Definition: meta.h:114
uint32_t offset
offset of bitmap data in this structure.
Definition: meta.h:119
int32_t stride
stride of bitmap data
Definition: meta.h:118
Cursor information.
Definition: meta.h:132
struct spa_point hotspot
offsets for hotspot in bitmap, this field has no meaning when there is no valid bitmap (see below)
Definition: meta.h:137
uint32_t id
cursor id.
Definition: meta.h:133
struct spa_point position
position on screen
Definition: meta.h:136
uint32_t bitmap_offset
offset of bitmap meta in this structure.
Definition: meta.h:139
Describes essential buffer header metadata such as flags and timestamps.
Definition: meta.h:67
uint32_t flags
Definition: meta.h:80
uint64_t seq
sequence number, increments with a media specific frequency
Definition: meta.h:84
int64_t pts
presentation timestamp in nanoseconds
Definition: meta.h:82
int64_t dts_offset
decoding timestamp as a difference with pts
Definition: meta.h:83
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
Definition: builder.h:53
void * data
Definition: builder.h:54
Definition: pod/pod.h:43
int32_t y
Definition: defs.h:111
int32_t x
Definition: defs.h:110
uint32_t width
Definition: defs.h:103
uint32_t height
Definition: defs.h:104
struct spa_point position
Definition: defs.h:117
struct spa_rectangle size
Definition: defs.h:118
Definition: spa/include/spa/support/loop.h:55
Definition: video/raw.h:176