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/*
[title]
\ref page_tutorial7
[title]
*/
/* [code] */
#include <stdio.h>
#include <errno.h>
#include <math.h>
#include <signal.h>
#include <spa/pod/builder.h>
#include <spa/param/latency-utils.h>
#include <pipewire/pipewire.h>
#include <pipewire/filter.h>
struct data;
struct port {
struct data *data;
};
struct data {
struct pw_main_loop *loop;
struct pw_filter *filter;
struct port *in_port;
struct port *out_port;
};
/* [on_process] */
static void on_process(void *userdata, struct spa_io_position *position)
{
struct data *data = userdata;
float *in, *out;
uint32_t n_samples = position->clock.duration;
pw_log_trace("do process %d", n_samples);
in = pw_filter_get_dsp_buffer(data->in_port, n_samples);
out = pw_filter_get_dsp_buffer(data->out_port, n_samples);
if (in == NULL || out == NULL)
return;
/* Simple passthrough - copy input to output.
* Here you could implement any audio processing:
* - Filters (lowpass, highpass, bandpass)
* - Effects (reverb, delay, distortion)
* - Dynamic processing (compressor, limiter)
* - Equalization
* - etc.
*/
memcpy(out, in, n_samples * sizeof(float));
}
/* [on_process] */
static const struct pw_filter_events filter_events = {
PW_VERSION_FILTER_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];
uint32_t n_params = 0;
uint8_t buffer[1024];
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), SIGINT, do_quit, &data);
pw_loop_add_signal(pw_main_loop_get_loop(data.loop), SIGTERM, do_quit, &data);
/* Create a simple filter, the simple filter manages the core and remote
* objects for you if you don't need to deal with them.
*
* Pass your events and a user_data pointer as the last arguments. This
* will inform you about the filter state. The most important event
* you need to listen to is the process event where you need to process
* the data.
*/
data.filter = pw_filter_new_simple(
pw_main_loop_get_loop(data.loop),
"audio-filter",
pw_properties_new(
PW_KEY_MEDIA_TYPE, "Audio",
PW_KEY_MEDIA_CATEGORY, "Filter",
PW_KEY_MEDIA_ROLE, "DSP",
NULL),
&filter_events,
&data);
/* make an audio DSP input port */
data.in_port = pw_filter_add_port(data.filter,
PW_DIRECTION_INPUT,
PW_FILTER_PORT_FLAG_MAP_BUFFERS,
sizeof(struct port),
pw_properties_new(
PW_KEY_FORMAT_DSP, "32 bit float mono audio",
PW_KEY_PORT_NAME, "input",
NULL),
NULL, 0);
/* make an audio DSP output port */
data.out_port = pw_filter_add_port(data.filter,
PW_DIRECTION_OUTPUT,
PW_FILTER_PORT_FLAG_MAP_BUFFERS,
sizeof(struct port),
pw_properties_new(
PW_KEY_FORMAT_DSP, "32 bit float mono audio",
PW_KEY_PORT_NAME, "output",
NULL),
NULL, 0);
/* Set processing latency information */
params[n_params++] = spa_process_latency_build(&b,
SPA_PARAM_ProcessLatency,
&SPA_PROCESS_LATENCY_INFO_INIT(
.ns = 10 * SPA_NSEC_PER_MSEC
));
/* Now connect this filter. We ask that our process function is
* called in a realtime thread. */
if (pw_filter_connect(data.filter,
PW_FILTER_FLAG_RT_PROCESS,
params, n_params) < 0) {
fprintf(stderr, "can't connect\n");
return -1;
}
/* and wait while we let things run */
pw_main_loop_run(data.loop);
pw_filter_destroy(data.filter);
pw_main_loop_destroy(data.loop);
pw_deinit();
return 0;
}
/* [code] */
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