example-clients/inprocess.c

   1 /** @file inprocess.c
   2  *
   3  * @brief This demonstrates the basic concepts for writing a client
   4  * that runs within the JACK server process.
   5  *
   6  * For the sake of example, a port_pair_t is allocated in
   7  * jack_initialize(), passed to inprocess() as an argument, then freed
   8  * in jack_finish().
   9  */
  10
  11 #include <stdlib.h>
  12 #include <stdio.h>
  13 #include <memory.h>
  14 #include <jack/jack.h>
  15
  16 /**
  17  * For the sake of example, an instance of this struct is allocated in
  18  * jack_initialize(), passed to inprocess() as an argument, then freed
  19  * in jack_finish().
  20  */
  21 typedef struct {
  22         jack_port_t *input_port;
  23         jack_port_t *output_port;
  24 } port_pair_t;
  25
  26 /**
  27  * Called in the realtime thread on every process cycle.  The entry
  28  * point name was passed to jack_set_process_callback() from
  29  * jack_initialize().  Although this is an internal client, its
  30  * process() interface is identical to @ref simple_client.c.
  31  *
  32  * @return 0 if successful; otherwise jack_finish() will be called and
  33  * the client terminated immediately.
  34  */
  35 int
  36 inprocess (jack_nframes_t nframes, void *arg)
  37 {
  38         port_pair_t *pp = arg;
  39         jack_default_audio_sample_t *out =
  40                 jack_port_get_buffer (pp->output_port, nframes);
  41         jack_default_audio_sample_t *in =
  42                 jack_port_get_buffer (pp->input_port, nframes);
  43
  44         memcpy (out, in, sizeof (jack_default_audio_sample_t) * nframes);
  45
  46         return 0;                       /* continue */
  47 }
  48
  49 /**
  50  * This required entry point is called after the client is loaded by
  51  * jack_internal_client_load().
  52  *
  53  * @param client pointer to JACK client structure.
  54  * @param load_init character string passed to the load operation.
  55  *
  56  * @return 0 if successful; otherwise jack_finish() will be called and
  57  * the client terminated immediately.
  58  */
  59 int
  60 jack_initialize (jack_client_t *client, const char *load_init)
  61 {
  62         port_pair_t *pp = malloc (sizeof (port_pair_t));
  63
  64         if (pp == NULL)
  65                 return 1;               /* heap exhausted */
  66
  67         jack_set_process_callback (client, inprocess, pp);
  68
  69         /* create a pair of ports */
  70         pp->input_port = jack_port_register (client, "input",
  71                                              JACK_DEFAULT_AUDIO_TYPE,
  72                                              JackPortIsInput, 0);
  73         pp->output_port = jack_port_register (client, "output",
  74                                               JACK_DEFAULT_AUDIO_TYPE,
  75                                               JackPortIsOutput, 0);
  76
  77         /* join the process() cycle */
  78         jack_activate (client);
  79
  80         /* try to connect to the first physical input & output ports */
  81
  82         if (jack_connect (client, "system:capture_1",
  83                           jack_port_name (pp->input_port))) {
  84                 fprintf (stderr, "cannot connect input port\n");
  85                 return 1;               /* terminate client */
  86         }
  87
  88         if (jack_connect (client, jack_port_name (pp->output_port),
  89                           "system:playback_1")) {
  90                 fprintf (stderr, "cannot connect output port\n");
  91                 return 1;               /* terminate client */
  92         }
  93
  94         return 0;                       /* success */
  95 }
  96
  97 /**
  98  * This required entry point is called immediately before the client
  99  * is unloaded, which could happen due to a call to
 100  * jack_internal_client_unload(), or a nonzero return from either
 101  * jack_initialize() or inprocess().
 102  *
 103  * @param arg the same parameter provided to inprocess().
 104  */
 105 void
 106 jack_finish (void *arg)
 107 {
 108         if (arg)
 109                 free ((port_pair_t *) arg);
 110 }