First Program in Jack

first_test.c

#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>

#include <jack/jack.h>
#include <jack/transport.h>

typedef jack_default_audio_sample_t sample_t;


char *client_name;
jack_client_t *client;


int process(jack_nframes_t nframes, void *arg) {
        return 0;
}

bool startClient() {
        jack_status_t status;
        while ((client = jack_client_open(client_name, 0, &status)) == 0) {
                fprintf(stderr, "jack server not running?\n");
                return false;
        }
        printf("Client started\n");
        return true;
}

int main(int argc, char *argv[]) {
        // start jack
        client_name = "Visualizer";
        if (!startClient()) {
                return -1; 
        }

        jack_set_process_callback(client, process, 0); 

        // activate jack
        if (jack_activate(client)) {
                fprintf(stderr, "cannot activate client");
                return 1;
        }
        printf("Jack activated\n");

        // get and print port names
        const char **port_names = jack_get_ports(client, NULL, NULL, 0); 
        for (int j = 0; port_names[j] != NULL; j++) {
                printf("%s\n", port_names[j]);
        }
}