guitfx/guitfx.c

#include "pipewire/keys.h"
#include "pipewire/port.h"
#include "spa/pod/iter.h"
#include "spa/utils/defs.h"
#include <stdio.h>
#include <signal.h>

#include <spa/pod/pod.h>
#include <spa/pod/builder.h>
#include <spa/control/control.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 *midi_in_port;
	struct port *out_port;

	//! elapsed time in number of samples
	uint64_t time;
};

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;
	uint64_t frame = data->time;
	data->time += n_samples;

	//printf("do process (%d samples) at %u\n", n_samples, frame);

	struct pw_buffer * b = pw_filter_dequeue_buffer(data->midi_in_port);
	if( b == NULL ) {
	   fprintf(stderr, "on_process(): no buffer for midi_in_port\n");
	   return;
	}

	struct spa_buffer * buf = b->buffer;
	spa_assert(buf->n_datas == 1);
	struct spa_data   * d   = &buf->datas[0];

	if( d->data ) {
	    struct spa_pod * pod =
			spa_pod_from_data(
			    d->data,
				d->maxsize,
				d->chunk->offset,
				d->chunk->size
			);

		if( pod ) {
		    if( spa_pod_is_sequence(pod) ) {
				struct spa_pod_sequence * pod_seq = (struct spa_pod_sequence*) pod;
				struct spa_pod_control * c;
				SPA_POD_SEQUENCE_FOREACH(pod_seq, c) {
				    if( c->type == SPA_CONTROL_Midi ) {
						unsigned sec =
						      (frame + c->offset)
							/ (float) position->clock.rate.denom;
						char * data = SPA_POD_BODY(&c->value);
						unsigned size = SPA_POD_BODY_SIZE(&c->value);

						printf("[%d] MIDI message (%d bytes) : %x, %x, %x\n", sec, size, data[0], data[1], data[2]);
					} else {
					    printf("on_process(): non midi-control\n");
					}
				}
			} else {
			    fprintf(stderr, "on_process(): unexpected POD that is not a sequence (midi_in_port)\n");
			}
		} else {
		    fprintf(stderr, "on_process(): pod is NULL\n");
		}
	} else {
	    fprintf(stderr, "on_process(): no data in buffer of midi_in_port\n");
	}

	pw_filter_queue_buffer(data->midi_in_port, b);


	in = pw_filter_get_dsp_buffer(data->in_port, n_samples);
	out = pw_filter_get_dsp_buffer(data->out_port, n_samples);

	if( in && out ) {
	   memcpy(out, in, n_samples * sizeof(float));
	}
}

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];
	uint8_t buffer[1024];
	struct spa_pod_builder b = SPA_POD_BUILDER_INIT(buffer, sizeof(buffer));

	pw_init(&argc, &argv);

	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);

	data.filter = pw_filter_new_simple(
			pw_main_loop_get_loop(data.loop),
			"Guitar FX",
			pw_properties_new(
				PW_KEY_MEDIA_TYPE, "Audio",
				PW_KEY_MEDIA_CATEGORY, "Filter",
				PW_KEY_MEDIA_ROLE, "DSP",
				NULL),
			&filter_events,
			&data);

	data.midi_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, "8 bit raw midi",
				PW_KEY_PORT_NAME, "midi-input",
				NULL
			),
			NULL, 0
		);

	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, "guitar input",
				NULL),
			NULL, 0);

	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, "guitar output",
				NULL),
			NULL, 0);

	params[0] = spa_process_latency_build(&b,
			SPA_PARAM_ProcessLatency,
			&SPA_PROCESS_LATENCY_INFO_INIT(
				.ns = 10 * SPA_NSEC_PER_MSEC
			));

	if (pw_filter_connect(data.filter,
				PW_FILTER_FLAG_RT_PROCESS,
				params, 1) < 0) {
		fprintf(stderr, "can't connect\n");
		return -1;
	}

	pw_main_loop_run(data.loop);

	pw_filter_destroy(data.filter);
	pw_main_loop_destroy(data.loop);
	pw_deinit();

	return 0;
}