pipewire/doc/examples/tutorial7.c

/*
  [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] */