src/example3.c

   1 /* Simple example of using SoX libraries
   2  *
   3  * Copyright (c) 2007-9 robs@users.sourceforge.net
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the
   7  * Free Software Foundation; either version 2 of the License, or (at your
   8  * option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
  13  * Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20 #ifdef NDEBUG /* N.B. assert used with active statements so enable always. */
  21 #undef NDEBUG /* Must undef above assert.h or other that might include it. */
  22 #endif
  23
  24 #include "sox.h"
  25 #include "util.h"
  26 #include <stdio.h>
  27 #include <assert.h>
  28
  29 /*
  30  * Example of a custom output message handler.
  31  */
  32 static void output_message(unsigned level, const char *filename, const char *fmt, va_list ap)
  33 {
  34   char const * const str[] = {"FAIL", "WARN", "INFO", "DBUG"};
  35   if (sox_globals.verbosity >= level) {
  36     fprintf(stderr, "%s ", str[min(level - 1, 3)]);
  37     sox_output_message(stderr, filename, fmt, ap);
  38     fprintf(stderr, "\n");
  39   }
  40 }
  41
  42 /*
  43  * On an alsa capable system, plays an audio file starting 10 seconds in.
  44  * Copes with sample-rate and channel change if necessary since its
  45  * common for audio drivers to to support subset of rates and channel
  46  * counts..
  47  * E.g. example3 song2.ogg
  48  *
  49  * Can easily be changed to work with other audio device drivers supported
  50  * by libSoX; e.g. "oss", "ao", "coreaudio", etc.
  51  * See the soxformat(7) manual page.
  52  */
  53 int main(int argc, char * argv[])
  54 {
  55   static sox_format_t * in, * out; /* input and output files */
  56   sox_effects_chain_t * chain;
  57   sox_effect_t * e;
  58   char * args[10];
  59
  60   assert(argc == 2);
  61   sox_globals.output_message_handler = output_message;
  62   sox_globals.verbosity = 1;
  63
  64   assert(sox_init() == SOX_SUCCESS);
  65   assert(in = sox_open_read(argv[1], NULL, NULL, NULL));
  66   /* Change "alsa" in this line to use an alternative audio device driver: */
  67   assert(out= sox_open_write("default", &in->signal, NULL, "alsa", NULL, NULL));
  68
  69   chain = sox_create_effects_chain(&in->encoding, &out->encoding);
  70
  71   e = sox_create_effect(sox_find_effect("input"));
  72   args[0] = (char *)in, assert(sox_effect_options(e, 1, args) == SOX_SUCCESS);
  73   assert(sox_add_effect(chain, e, &in->signal, &in->signal) == SOX_SUCCESS);
  74
  75   e = sox_create_effect(sox_find_effect("trim"));
  76   args[0] = "10", assert(sox_effect_options(e, 1, args) == SOX_SUCCESS);
  77   assert(sox_add_effect(chain, e, &in->signal, &in->signal) == SOX_SUCCESS);
  78
  79   if (in->signal.rate != out->signal.rate) {
  80     e = sox_create_effect(sox_find_effect("rate"));
  81     assert(sox_effect_options(e, 0, NULL) == SOX_SUCCESS);
  82     assert(sox_add_effect(chain, e, &in->signal, &out->signal) == SOX_SUCCESS);
  83   }
  84
  85   if (in->signal.channels != out->signal.channels) {
  86     e = sox_create_effect(sox_find_effect("channels"));
  87     assert(sox_effect_options(e, 0, NULL) == SOX_SUCCESS);
  88     assert(sox_add_effect(chain, e, &in->signal, &out->signal) == SOX_SUCCESS);
  89   }
  90
  91   e = sox_create_effect(sox_find_effect("output"));
  92   args[0] = (char *)out, assert(sox_effect_options(e, 1, args) == SOX_SUCCESS);
  93   assert(sox_add_effect(chain, e, &in->signal, &out->signal) == SOX_SUCCESS);
  94
  95   sox_flow_effects(chain, NULL, NULL);
  96
  97   sox_delete_effects_chain(chain);
  98   sox_close(out);
  99   sox_close(in);
 100   sox_quit();
 101
 102   return 0;
 103 }