[LAD] jack app help

hello, I am trying to develop an app using jack. My first goal is to play a stereo wav. I've used clockloop http://plugin.org.uk/clockloop by Steve Harris as a starting point. It uses libsndfile to open a mono wav. I've reached a point where 2 outputs are created and connected to the first two outputs of the sound card. I managed to send a mono file to both outs. I've opened a stereo file, but I'm having trouble outputting it correctly. I am a bit confused on how to continue. If someone could give me some pointers would be much appreciated. thanks in advance stefanos This is what I have so far: //================ audio.c =============== /* * Copyright (C) 2003 Steve Harris * * 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. */ #include <stdlib.h> #include <jack/jack.h> #include "audio.h" #include <stdio.h> buffer_t *buffers = NULL; unsigned int buffer_size = 0; unsigned int num_buffers = 0; unsigned int play_pos = 0; float gain_inc = 0.01f; float c_gain = 0.1f; jack_client_t *client; jack_port_t *output_port_ML; jack_port_t *output_port_MR; int process(jack_nframes_t nframes, void *arg) { unsigned int i,j; sample_t *outML = (sample_t *)jack_port_get_buffer(output_port_ML, nframes); sample_t *outMR = (sample_t *)jack_port_get_buffer(output_port_MR, nframes); for (j=0; j<nframes; j++) { outML[j] = 0.0f; outMR[j] = 0.0f; } for (i=0; i<num_buffers; i=i++) { if (buffers[i].state == on) { for (j=0; j<nframes; j++) { outML[j] += (buffers[i].data[(play_pos + j) % buffer_size]) * c_gain; outMR[j] += (buffers[i].data[(play_pos + j) % buffer_size]) * c_gain; } } } play_pos = (play_pos + nframes) % buffer_size; return 0; } //====================== audio.h ====================== #ifndef AUDIO_H #define AUDIO_H #include <jack/jack.h> typedef jack_default_audio_sample_t sample_t; typedef enum { off, on, ramp_down, ramp_up, } b_state; typedef struct { float *data; float gain; b_state state; } buffer_t; extern buffer_t *buffers; extern unsigned int buffer_size; extern unsigned int num_buffers; extern jack_client_t *client; extern jack_port_t *output_port_ML; extern jack_port_t *output_port_MR; extern float gain_inc; int process(jack_nframes_t nframes, void *arg); #endif //=================== clockloop.c ======================= /* * Copyright (C) 2003 Steve Harris * * 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. */ #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <alsa/asoundlib.h> #include <sndfile.h> #include "audio.h" void midi_action(snd_seq_t * seq_handle); jack_client_t *client; jack_port_t *output_port_ML; jack_port_t *output_port_MR; int main(int argc, char **argv) { unsigned int i; int count; const char **ports; if (argc < 2) { fprintf(stderr, "Usage: %s <audio-file> ...\n", argv[0]); return 1; } /* JACK stuff */ if ((client = jack_client_new("clock-loop")) == 0) { fprintf (stderr, "jack server not running?\n"); return 1; } jack_set_process_callback (client, process, 0); output_port_ML = jack_port_register (client, "out_Master_Left", JACK_DEFAULT_AUDIO_TYPE, JackPortIsOutput, 0); output_port_MR = jack_port_register (client, "out_Master_Right", JACK_DEFAULT_AUDIO_TYPE, JackPortIsOutput, 0); num_buffers = argc - 1; buffers = malloc(sizeof(buffer_t) * num_buffers * 2); // *2 for stereo buffer_size = 0; for (i = 0; i<num_buffers; i++) { SNDFILE *sf; SF_INFO sfi; sfi.format = 0; sf = sf_open(argv[i + 1], SFM_READ, &sfi); /*if (sfi.channels != 1) { fprintf(stderr, "%s: only works with mono files\n", argv[0]); return 1; }*/ if (!buffer_size) { buffer_size = sfi.frames; gain_inc = (float)jack_get_buffer_size(client) / (buffer_size * 8.0f); buffers[i].state = on; buffers[i].gain = 1.0f; } else { buffers[i].state = off; buffers[i].gain = 0.0f; } if (sfi.frames > buffer_size) { fprintf(stderr, "%s warning: '%s' is %d frames longer than reference file, truncating\n", argv[0], argv[i+1], (int)(sfi.frames - buffer_size)); } buffers[i].data = malloc(buffer_size * sizeof(float)); count = sf_read_float(sf, buffers[i].data, buffer_size); if (count < buffer_size) { fprintf(stderr, "%s warning: only read %d/%d frames from file '%s', zero padding\n", argv[0], count, buffer_size, argv[i+1]); memset(buffers[i].data + count, 0, buffer_size - count); } sf_close(sf); } if (jack_activate(client)) { fprintf (stderr, "cannot activate client"); exit(1); } /* connect the ports*/ if ((ports = jack_get_ports (client, NULL, NULL, JackPortIsPhysical|JackPortIsInput)) == NULL) { fprintf(stderr, "Cannot find any physical playback ports\n"); exit(1); } if (jack_connect (client, jack_port_name (output_port_ML), ports[0])) { fprintf (stderr, "cannot connect output ports\n"); } if (jack_connect (client, jack_port_name (output_port_MR), ports[1])) { fprintf (stderr, "cannot connect output ports\n"); } for(;;) sleep (1); }