example-clients/tw.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)
  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 int
  59 process (jack_nframes_t nframes, void* arg)
  60 {
  61         jack_client_t* client = (jack_client_t*) arg;
  62
  63         while ((nframes = jack_thread_wait (client, _process (nframes))) != 0);
  64 }
  65
  66 /**
  67  * JACK calls this shutdown_callback if the server ever shuts down or
  68  * decides to disconnect the client.
  69  */
  70 void
  71 jack_shutdown (void *arg)
  72 {
  73         exit (1);
  74 }
  75
  76 int
  77 main (int argc, char *argv[])
  78 {
  79         const char **ports;
  80         const char *client_name;
  81         const char *server_name = NULL;
  82         jack_options_t options = JackNullOption;
  83         jack_status_t status;
  84
  85         if (argc >= 2) {                /* client name specified? */
  86                 client_name = argv[1];
  87                 if (argc >= 3) {        /* server name specified? */
  88                         server_name = argv[2];
  89                         options |= JackServerName;
  90                 }
  91         } else {                        /* use basename of argv[0] */
  92                 client_name = strrchr(argv[0], '/');
  93                 if (client_name == 0) {
  94                         client_name = argv[0];
  95                 } else {
  96                         client_name++;
  97                 }
  98         }
  99
 100         /* open a client connection to the JACK server */
 101
 102         client = jack_client_open (client_name, options, &status, server_name);
 103         if (client == NULL) {
 104                 fprintf (stderr, "jack_client_open() failed, "
 105                          "status = 0x%2.0x\n", status);
 106                 if (status & JackServerFailed) {
 107                         fprintf (stderr, "Unable to connect to JACK server\n");
 108                 }
 109                 exit (1);
 110         }
 111         if (status & JackServerStarted) {
 112                 fprintf (stderr, "JACK server started\n");
 113         }
 114         if (status & JackNameNotUnique) {
 115                 client_name = jack_get_client_name(client);
 116                 fprintf (stderr, "unique name `%s' assigned\n", client_name);
 117         }
 118
 119         /* tell the JACK server to call `process()' whenever
 120            there is work to be done.
 121         */
 122
 123         jack_set_process_callback (client, process, client);
 124
 125         /* tell the JACK server to call `jack_shutdown()' if
 126            it ever shuts down, either entirely, or if it
 127            just decides to stop calling us.
 128         */
 129
 130         jack_on_shutdown (client, jack_shutdown, 0);
 131
 132         /* display the current sample rate.
 133          */
 134
 135         printf ("engine sample rate: %" PRIu32 "\n",
 136                 jack_get_sample_rate (client));
 137
 138         /* create two ports */
 139
 140         input_port = jack_port_register (client, "input",
 141                                          JACK_DEFAULT_AUDIO_TYPE,
 142                                          JackPortIsInput, 0);
 143         output_port = jack_port_register (client, "output",
 144                                           JACK_DEFAULT_AUDIO_TYPE,
 145                                           JackPortIsOutput, 0);
 146
 147         if ((input_port == NULL) || (output_port == NULL)) {
 148                 fprintf(stderr, "no more JACK ports available\n");
 149                 exit (1);
 150         }
 151
 152         /* Tell the JACK server that we are ready to roll.  Our
 153          * process() callback will start running now. */
 154
 155         if (jack_activate (client)) {
 156                 fprintf (stderr, "cannot activate client");
 157                 exit (1);
 158         }
 159
 160         /* Connect the ports.  You can't do this before the client is
 161          * activated, because we can't make connections to clients
 162          * that aren't running.  Note the confusing (but necessary)
 163          * orientation of the driver backend ports: playback ports are
 164          * "input" to the backend, and capture ports are "output" from
 165          * it.
 166          */
 167
 168         ports = jack_get_ports (client, NULL, NULL,
 169                                 JackPortIsPhysical|JackPortIsOutput);
 170         if (ports == NULL) {
 171                 fprintf(stderr, "no physical capture ports\n");
 172                 exit (1);
 173         }
 174
 175         if (jack_connect (client, ports[0], jack_port_name (input_port))) {
 176                 fprintf (stderr, "cannot connect input ports\n");
 177         }
 178
 179         free (ports);
 180
 181         ports = jack_get_ports (client, NULL, NULL,
 182                                 JackPortIsPhysical|JackPortIsInput);
 183         if (ports == NULL) {
 184                 fprintf(stderr, "no physical playback ports\n");
 185                 exit (1);
 186         }
 187
 188         if (jack_connect (client, jack_port_name (output_port), ports[0])) {
 189                 fprintf (stderr, "cannot connect output ports\n");
 190         }
 191
 192         free (ports);
 193
 194         /* keep running until the transport stops */
 195
 196         while (client_state != Exit) {
 197                 sleep (1);
 198         }
 199
 200         jack_client_close (client);
 201         exit (0);
 202 }