Jack Loop Back Microphone to Speaker.

/*
    Programmer: Shane B.
    Date: 12/12/12
    Purpose: Learn how to minipulate sound packets before looping into the headphone
*/



/*
    === Load Libraries===
*/
#include <stdio.h>
//#include <errno.h>
//#include <unistd.h>
//#include <stdlib.h>
//#include <string.h>

#include <jack/jack.h>


/*
    ===Define Globally set variables/pointers===
*/
jack_port_t *input_port;
jack_port_t *output_port;




/*
    ===Begin Other Helpful Functions===
*/


int
process (jack_nframes_t nframes, void *arg)

{
    jack_default_audio_sample_t *out = (jack_default_audio_sample_t *)
    jack_port_get_buffer (output_port, nframes);

    jack_default_audio_sample_t *in = (jack_default_audio_sample_t *)
    fprintf("%lu", in);
        jack_port_get_buffer (input_port, nframes);

    memcpy (out, in, sizeof (jack_default_audio_sample_t) * nframes);

    return 0;
}

int
srate (jack_nframes_t nframes, void *arg)
{
    printf ("the sample rate is now %lu/sec\n", nframes);
    return 0;
}

void
jack_shutdown (void *arg)
{
    exit (1);
}





/*

    ===Begin Logic Run-time===
*/

int
main (int argc, char *argv[])
{
    /*
        ---------------------------------------------------------------------------------------------------------------
        Here we are attempting to open up a client connectiong with the JACK server
    */

    //Define pointer variable for connecting to the JACK server
    jack_client_t *client;

    //Check if the client can connect to the local jack server
    if ((client = jack_client_new("crypt")) == 0) {
        fprintf (stderr, "jack server not running?\n");
        return 1;
    }


    //Assuming we have connected to the JACK server, estiablish input/output connection ports to open up
    input_port = jack_port_register (client, "input", JACK_DEFAULT_AUDIO_TYPE, JackPortIsInput, 0);
    output_port = jack_port_register (client, "output", JACK_DEFAULT_AUDIO_TYPE, JackPortIsOutput, 0);

    //Lets define some Call back functions that can be triggered during audio runtime
        //When there is work (audio) to be proccessed call the function proccess()
        jack_set_process_callback (client, process, 0);

        //When the sample rate of the audio stream changes call the function srate()
        jack_set_sample_rate_callback (client, srate, 0);

        //When the JACK server stops talking or shuts down, tell the application(local) to close
        jack_on_shutdown (client, jack_shutdown, 0);


    //If we can activate the JACK client then we have a connection, continue running...
    if (jack_activate (client)) {
        fprintf (stderr, "cannot activate client");
        return 1;
    }

    //Define port pointer variable
    const char **ports;

    //Check if physical output ports exist...
    if ((ports = jack_get_ports (client, NULL, NULL, JackPortIsPhysical|JackPortIsOutput)) == NULL) {
        fprintf(stderr, "Cannot find any physical capture ports\n");
        exit(1);
    }

    //Check if we can connect to physical input ports with the client....
    if (jack_connect (client, ports[0], jack_port_name (input_port))) {
        fprintf (stderr, "cannot connect input ports\n");
    }

    //Free port pointer
    free (ports);

    //
    if ((ports = jack_get_ports (client, NULL, NULL, JackPortIsPhysical|JackPortIsInput)) == NULL) {
        fprintf(stderr, "Cannot find any physical playback ports\n");
        exit(1);
    }

    //Connect all known ports....
    int i=0;
    while(ports[i]!=NULL){
      if (jack_connect (client, jack_port_name (output_port), ports[i])) {
        fprintf (stderr, "cannot connect output ports\n");
      }
      i++;
    }

    free (ports);

    for(;;)


    /*KIRBY: Close the client*/
    jack_client_close (client);
    exit (0);
}