PipeWire  0.3.71
audio-src.c

doc} audio-src.c title
doc} audio-src.c doc

/* PipeWire */
/* SPDX-FileCopyrightText: Copyright © 2018 Wim Taymans */
/* SPDX-License-Identifier: MIT */
/*
[title]
Audio source using \ref pw_stream "pw_stream".
[title]
*/
#include <stdio.h>
#include <errno.h>
#include <math.h>
#include <signal.h>
#define M_PI_M2 ( M_PI + M_PI )
#define DEFAULT_RATE 44100
#define DEFAULT_CHANNELS 2
#define DEFAULT_VOLUME 0.7
struct data {
struct pw_main_loop *loop;
struct pw_stream *stream;
double accumulator;
};
static void fill_f32(struct data *d, void *dest, int n_frames)
{
float *dst = dest, val;
int i, c;
for (i = 0; i < n_frames; i++) {
d->accumulator += M_PI_M2 * 440 / DEFAULT_RATE;
if (d->accumulator >= M_PI_M2)
d->accumulator -= M_PI_M2;
val = sin(d->accumulator) * DEFAULT_VOLUME;
for (c = 0; c < DEFAULT_CHANNELS; c++)
*dst++ = val;
}
}
/* our data processing function is in general:
*
* struct pw_buffer *b;
* b = pw_stream_dequeue_buffer(stream);
*
* .. generate stuff in the buffer ...
*
* pw_stream_queue_buffer(stream, b);
*/
static void on_process(void *userdata)
{
struct data *data = userdata;
struct pw_buffer *b;
struct spa_buffer *buf;
int n_frames, stride;
uint8_t *p;
if ((b = pw_stream_dequeue_buffer(data->stream)) == NULL) {
pw_log_warn("out of buffers: %m");
return;
}
buf = b->buffer;
if ((p = buf->datas[0].data) == NULL)
return;
stride = sizeof(float) * DEFAULT_CHANNELS;
n_frames = SPA_MIN(b->requested, buf->datas[0].maxsize / stride);
fill_f32(data, p, n_frames);
buf->datas[0].chunk->offset = 0;
buf->datas[0].chunk->stride = stride;
buf->datas[0].chunk->size = n_frames * stride;
pw_stream_queue_buffer(data->stream, b);
}
static const struct pw_stream_events stream_events = {
.process = on_process,
};
static void do_quit(void *userdata, int signal_number)
{
struct data *data = userdata;
pw_main_loop_quit(data->loop);
}
int main(int argc, char *argv[])
{
struct data data = { 0, };
const struct spa_pod *params[1];
uint8_t buffer[1024];
struct pw_properties *props;
struct spa_pod_builder b = SPA_POD_BUILDER_INIT(buffer, sizeof(buffer));
pw_init(&argc, &argv);
/* make a main loop. If you already have another main loop, you can add
* the fd of this pipewire mainloop to it. */
data.loop = pw_main_loop_new(NULL);
pw_loop_add_signal(pw_main_loop_get_loop(data.loop), SIGTERM, do_quit, &data);
/* Create a simple stream, the simple stream manages the core and remote
* objects for you if you don't need to deal with them.
*
* If you plan to autoconnect your stream, you need to provide at least
* media, category and role properties.
*
* 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 produce
* the data.
*/
PW_KEY_MEDIA_CATEGORY, "Playback",
NULL);
if (argc > 1)
/* Set stream target if given on command line */
"audio-src",
props,
&stream_events,
&data);
/* Make one parameter with the supported formats. The SPA_PARAM_EnumFormat
* id means that this is a format enumeration (of 1 value). */
.channels = DEFAULT_CHANNELS,
.rate = DEFAULT_RATE ));
/* Now connect this stream. We ask that our process function is
* called in a realtime thread. */
params, 1);
/* and wait while we let things run */
return 0;
}