src/example4.c

   1 /* Simple example of using SoX libraries
   2  *
   3  * Copyright (c) 2009 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 #include "sox.h"
  21 #include <stdio.h>
  22
  23 /* Concatenate audio files.  Note that the files must have the same number
  24  * of channels and the same sample rate.
  25  *
  26  * Usage: example4 input-1 input-2 [... input-n] output
  27  */
  28
  29 #define check(x) do if (!(x)) { \
  30   fprintf(stderr, "check failed: %s\n", #x); goto error; } while (0)
  31
  32 int main(int argc, char * argv[])
  33 {
  34   sox_format_t * output = NULL;
  35   int i;
  36
  37   check(argc >= 1 + 2 + 1); /* Need at least 2 input files + 1 output file. */
  38   check(sox_init() == SOX_SUCCESS);
  39
  40   /* Defer openning the output file as we want to set its characteristics
  41    * based on those of the input files. */
  42
  43   for (i = 1; i < argc - 1; ++i) { /* For each input file... */
  44     sox_format_t * input;
  45     static sox_signalinfo_t signal; /* static quashes `uninitialised' warning.*/
  46
  47     /* The (maximum) number of samples that we shall read/write at a time;
  48      * chosen as a rough match to typical operating system I/O buffer size: */
  49     #define MAX_SAMPLES (size_t)2048
  50     sox_sample_t samples[MAX_SAMPLES]; /* Temporary store whilst copying. */
  51     size_t number_read;
  52
  53     /* Open this input file: */
  54     check(input = sox_open_read(argv[i], NULL, NULL, NULL));
  55
  56     if (i == 1) { /* If this is the first input file... */
  57
  58       /* Open the output file using the same signal and encoding character-
  59        * istics as the first input file.  Note that here, input->signal.length
  60        * will not be equal to the output file length so we are relying on
  61        * libSoX to set the output length correctly (i.e. non-seekable output
  62        * is not catered for); an alternative would be to first calculate the
  63        * output length by summing the lengths of the input files and modifying
  64        * the second parameter to sox_open_write accordingly. */
  65       check(output = sox_open_write(argv[argc - 1],
  66             &input->signal, &input->encoding, NULL, NULL, NULL));
  67
  68       /* Also, we'll store the signal characteristics of the first file
  69        * so that we can check that these match those of the other inputs: */
  70       signal = input->signal;
  71     }
  72     else { /* Second or subsequent input file... */
  73
  74       /* Check that this input file's signal matches that of the first file: */
  75       check(input->signal.channels == signal.channels);
  76       check(input->signal.rate == signal.rate);
  77     }
  78
  79     /* Copy all of the audio from this input file to the output file: */
  80     while ((number_read = sox_read(input, samples, MAX_SAMPLES)))
  81       check(sox_write(output, samples, number_read) == number_read);
  82
  83     check(sox_close(input) == SOX_SUCCESS); /* Finished with this input file.*/
  84   }
  85
  86   check(sox_close(output) == SOX_SUCCESS); /* Finished with the output file. */
  87   output = NULL;
  88   check(sox_quit() == SOX_SUCCESS);
  89   return 0;
  90
  91 error: /* Truncate output file on error: */
  92   if (output) {
  93     FILE * f;
  94     sox_close(output);
  95     if ((f = fopen(argv[argc - 1], "w"))) fclose(f);
  96   }
  97   return 1;
  98 }