example-clients/simple_client.c

   1 /** @file simple_client.c
   2  *
   3  * @brief This simple client demonstrates the basic features of JACK
   4  * as they would be used by many applications.
   5  */
   6
   7 #include <stdio.h>
   8 #include <errno.h>
   9 #include <unistd.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12
  13 #include <jack/jack.h>
  14
  15 jack_port_t *input_port;
  16 jack_port_t *output_port;
  17 jack_client_t *client;
  18
  19 /* a simple state machine for this client */
  20 volatile enum {
  21         Init,
  22         Run,
  23         Exit
  24 } client_state = Init;
  25
  26 /**
  27  * The process callback for this JACK application is called in a
  28  * special realtime thread once for each audio cycle.
  29  *
  30  * This client follows a simple rule: when the JACK transport is
  31  * running, copy the input port to the output.  When it stops, exit.
  32  */
  33 int
  34 process (jack_nframes_t nframes, void *arg)
  35 {
  36         jack_default_audio_sample_t *in, *out;
  37         jack_transport_state_t ts = jack_transport_query(client, NULL);
  38
  39         if (ts == JackTransportRolling) {
  40
  41                 if (client_state == Init)
  42                         client_state = Run;
  43
  44                 in = jack_port_get_buffer (input_port, nframes);
  45                 out = jack_port_get_buffer (output_port, nframes);
  46                 memcpy (out, in,
  47                         sizeof (jack_default_audio_sample_t) * nframes);
  48
  49         } else if (ts == JackTransportStopped) {
  50
  51                 if (client_state == Run)
  52                         client_state = Exit;
  53         }
  54
  55         return 0;
  56 }
  57
  58 /**
  59  * JACK calls this shutdown_callback if the server ever shuts down or
  60  * decides to disconnect the client.
  61  */
  62 void
  63 jack_shutdown (void *arg)
  64 {
  65         exit (1);
  66 }
  67
  68 int
  69 main (int argc, char *argv[])
  70 {
  71         const char **ports;
  72         const char *client_name;
  73         const char *server_name = NULL;
  74         jack_options_t options = JackNullOption;
  75         jack_status_t status;
  76
  77         if (argc >= 2) {                /* client name specified? */
  78                 client_name = argv[1];
  79                 if (argc >= 3) {        /* server name specified? */
  80                         server_name = argv[2];
  81                         options |= JackServerName;
  82                 }
  83         } else {                        /* use basename of argv[0] */
  84                 client_name = strrchr(argv[0], '/');
  85                 if (client_name == 0) {
  86                         client_name = argv[0];
  87                 } else {
  88                         client_name++;
  89                 }
  90         }
  91
  92         /* open a client connection to the JACK server */
  93
  94         client = jack_client_open (client_name, options, &status, server_name);
  95         if (client == NULL) {
  96                 fprintf (stderr, "jack_client_open() failed, "
  97                          "status = 0x%2.0x\n", status);
  98                 if (status & JackServerFailed) {
  99                         fprintf (stderr, "Unable to connect to JACK server\n");
 100                 }
 101                 exit (1);
 102         }
 103         if (status & JackServerStarted) {
 104                 fprintf (stderr, "JACK server started\n");
 105         }
 106         if (status & JackNameNotUnique) {
 107                 client_name = jack_get_client_name(client);
 108                 fprintf (stderr, "unique name `%s' assigned\n", client_name);
 109         }
 110
 111         /* tell the JACK server to call `process()' whenever
 112            there is work to be done.
 113         */
 114
 115         jack_set_process_callback (client, process, 0);
 116
 117         /* tell the JACK server to call `jack_shutdown()' if
 118            it ever shuts down, either entirely, or if it
 119            just decides to stop calling us.
 120         */
 121
 122         jack_on_shutdown (client, jack_shutdown, 0);
 123
 124         /* display the current sample rate.
 125          */
 126
 127         printf ("engine sample rate: %" PRIu32 "\n",
 128                 jack_get_sample_rate (client));
 129
 130         /* create two ports */
 131
 132         input_port = jack_port_register (client, "input",
 133                                          JACK_DEFAULT_AUDIO_TYPE,
 134                                          JackPortIsInput, 0);
 135         output_port = jack_port_register (client, "output",
 136                                           JACK_DEFAULT_AUDIO_TYPE,
 137                                           JackPortIsOutput, 0);
 138
 139         if ((input_port == NULL) || (output_port == NULL)) {
 140                 fprintf(stderr, "no more JACK ports available\n");
 141                 exit (1);
 142         }
 143
 144         /* Tell the JACK server that we are ready to roll.  Our
 145          * process() callback will start running now. */
 146
 147         if (jack_activate (client)) {
 148                 fprintf (stderr, "cannot activate client");
 149                 exit (1);
 150         }
 151
 152         /* Connect the ports.  You can't do this before the client is
 153          * activated, because we can't make connections to clients
 154          * that aren't running.  Note the confusing (but necessary)
 155          * orientation of the driver backend ports: playback ports are
 156          * "input" to the backend, and capture ports are "output" from
 157          * it.
 158          */
 159
 160         ports = jack_get_ports (client, NULL, NULL,
 161                                 JackPortIsPhysical|JackPortIsOutput);
 162         if (ports == NULL) {
 163                 fprintf(stderr, "no physical capture ports\n");
 164                 exit (1);
 165         }
 166
 167         if (jack_connect (client, ports[0], jack_port_name (input_port))) {
 168                 fprintf (stderr, "cannot connect input ports\n");
 169         }
 170
 171         free (ports);
 172
 173         ports = jack_get_ports (client, NULL, NULL,
 174                                 JackPortIsPhysical|JackPortIsInput);
 175         if (ports == NULL) {
 176                 fprintf(stderr, "no physical playback ports\n");
 177                 exit (1);
 178         }
 179
 180         if (jack_connect (client, jack_port_name (output_port), ports[0])) {
 181                 fprintf (stderr, "cannot connect output ports\n");
 182         }
 183
 184         free (ports);
 185
 186         /* keep running until the transport stops */
 187
 188         while (client_state != Exit) {
 189                 sleep (1);
 190         }
 191
 192         jack_client_close (client);
 193         exit (0);
 194 }