A skeleton program to get data from Jack Audio Connection Kit: Difference between revisions

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/***************************************************************************
* jack-skeleton
*
* This program is a skeleton program to use to get data from a Jack
* source to process.
*
* Written:
* May 2013
* by Rob Frohne
* e-mail: Rob "dot" Frohne "at sign" wallawalla "dot" edu
*
****************************************************************************/

/* To build this program, you must have jack audio connection kit installed.
* At the command prompt:
* $ gcc jack-skeleton.c -ljack -o jack-skeleton
*/

/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/


#include <jack/jack.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <math.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <getopt.h>
#include <string.h>


/* global jack variables. */
jack_client_t *test_client;
jack_port_t *audio_input_port_left, *audio_input_port_right;

/* To use this command, you need to $ jack-skeleton
* assuming those are the options you want.
* Options are:
* -? for help
* -v or --verbose for verbose response.
*/
/* Flag set by ‘--verbose’. */
static int verbose_flag;
// Specify options and their syntax
static struct option long_options[] =
{
/* These options set a flag. */
{"verbose", no_argument, &verbose_flag, 1},
{"brief", no_argument, &verbose_flag, 0},
/* These options don't set a flag.
We distinguish them by their indices. */
{"help", no_argument, 0, '?'},
{0, 0, 0, 0}
};

/* Close things opened. */
void cleanup(void) {
if(test_client != NULL) {
jack_deactivate(test_client);
jack_client_close(test_client);
}
}

/* This is the function that is called when and if jackd shuts down. */
void jack_shutdown (void *arg)
{
fprintf (stderr, "JACK shutdown\n");
cleanup();
abort();
}
/* This is the callback process that gets data from jack.*/
int process(jack_nframes_t number_of_frames, void *arg)
{ //Use static variables if you want to save things between calls to
// this process.
jack_default_audio_sample_t *sample_buffer_left =
(jack_default_audio_sample_t *) jack_port_get_buffer(audio_input_port_left, number_of_frames);
jack_default_audio_sample_t *sample_buffer_right =
(jack_default_audio_sample_t *) jack_port_get_buffer(audio_input_port_right, number_of_frames);
jack_nframes_t i;
//This is where you get your data in the format that the program using /dev/dsp needs it.
for(i = 0; i < number_of_frames; i++){
// This is where you process your data.
}
return 0;
}


int main (int argc, char *argv[]){
int error;
char * fifo_name = PIPE_NAME;
// Iterate over options and handle each one as appropriate
int c;
// The function getopt_long stores the option index here.
int option_index = 0;

while ( (c = getopt_long ( argc, argv, "v?f:",
long_options, &option_index )) != -1 )
{
switch ( c )
{
case 0:
// If this option set a flag, do nothing else now.
if ( long_options[option_index].flag != 0 )
break;

case 'v':
verbose_flag = 1;
break;

case '?':

default :
printf(
"Options are: \n"
"-v or --verbose for verbose output\n"
"Typing EOF (ctrl-D) (ctrl-capitol D, to be exact) will end the program.\n");
exit ( 0 );
}
}
//Create a new jack client, then make sure everything went ok.
test_client = jack_client_open("Test Client",(jack_options_t)(!JackServerName),NULL);
if (test_client == 0) {
fprintf(stderr,"Cannot connect to the jackd as a client.\n");
cleanup();
return 1;
}
/* Set up Jack */
//Set up the jack shutdown routine in case we want to do something special on shutdown of jack.
jack_on_shutdown (test_client, jack_shutdown, 0);

//Create and register new audio input ports.
audio_input_port_left = jack_port_register(test_client, "Audio FIFO Port_left",
JACK_DEFAULT_AUDIO_TYPE, JackPortIsInput, 0);
if (audio_input_port_left == NULL) {
fprintf(stderr, "Error: jack_port_register returned NULL for left channel.\n");
cleanup();
return 1;
}
audio_input_port_right = jack_port_register(test_client, "Audio FIFO Port_right",
JACK_DEFAULT_AUDIO_TYPE, JackPortIsInput, 0);
if (audio_input_port_right == NULL) {
fprintf(stderr, "Error: jack_port_register returned NULL for right channel.\n");
cleanup();
return 1;
}
//Tell the jackd server what function call when it wants more audio data.
if((error = jack_set_process_callback(test_client, process, &pipe_handle)) != 0) {
fprintf(stderr, "Jack could not set the callback, (error %i).\n", error);
cleanup();
return 1;
}
//Tell jack it's ok to start asking us for audio data.
if((error = jack_activate(test_client)) != 0) {
fprintf(stderr, "Jack could not activate the client (error %i).\n", error);
cleanup();
return 1;
}
else if(verbose_flag) fprintf(stderr,"Activated client.\n");
//Connect the ports.
if (jack_connect (test_client,"system:capture_1", jack_port_name (audio_input_port_left))) {
fprintf (stderr, "cannot connect port: system:capture_1\n");
}
else if(verbose_flag) fprintf(stderr, "Connected to port: system:capture_1\n");
if (jack_connect (test_client,"system:capture_2", jack_port_name (audio_input_port_right))) {
fprintf (stderr, "cannot connect port: system:capture_2\n");
}
else if(verbose_flag) fprintf(stderr, "Connected to port: system:capture_2\n");
while(getchar() != EOF){
//Quit on ctrl-D.
}
/* Close things opened. */
cleanup();

return 0;
}

Latest revision as of 18:34, 19 May 2013

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