/* Simple example of using SoX libraries * * Copyright (c) 2007-8 robs@users.sourceforge.net * * 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., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ #ifdef NDEBUG /* N.B. assert used with active statements so enable always. */#undef NDEBUG /* Must undef above assert.h or other that might include it. */#endif #include "sox.h"#include <stdlib.h>#include <stdio.h>#include <assert.h> static sox_format_t * in, * out; /* input and output files */ /* The function that will be called to input samples into the effects chain. * In this example, we get samples to process from a SoX-openned audio file. * In a different application, they might be generated or come from a different * part of the application. */static int input_drain(    sox_effect_t * effp, sox_sample_t * obuf, size_t * osamp){  (void)effp;   /* This parameter is not needed in this example */   /* ensure that *osamp is a multiple of the number of channels. */  *osamp -= *osamp % effp->out_signal.channels;   /* Read up to *osamp samples into obuf; store the actual number read   * back to *osamp */  *osamp = sox_read(in, obuf, *osamp);   /* sox_read may return a number that is less than was requested; only if   * 0 samples is returned does it indicate that end-of-file has been reached   * or an error has occurred */  if (!*osamp && in->sox_errno)    fprintf(stderr, "%s: %s\n", in->filename, in->sox_errstr);  return *osamp? SOX_SUCCESS : SOX_EOF;} /* The function that will be called to output samples from the effects chain. * In this example, we store the samples in a SoX-opened audio file. * In a different application, they might perhaps be analysed in some way, * or displayed as a wave-form */static int output_flow(sox_effect_t *effp LSX_UNUSED, sox_sample_t const * ibuf,    sox_sample_t * obuf LSX_UNUSED, size_t * isamp, size_t * osamp){  /* Write out *isamp samples */  size_t len = sox_write(out, ibuf, *isamp);   /* len is the number of samples that were actually written out; if this is   * different to *isamp, then something has gone wrong--most often, it's   * out of disc space */  if (len != *isamp) {    fprintf(stderr, "%s: %s\n", out->filename, out->sox_errstr);    return SOX_EOF;  }   /* Outputting is the last `effect' in the effect chain so always passes   * 0 samples on to the next effect (as there isn't one!) */  *osamp = 0;   (void)effp;   /* This parameter is not needed in this example */   return SOX_SUCCESS; /* All samples output successfully */} /* A `stub' effect handler to handle inputting samples to the effects * chain; the only function needed for this example is `drain' */static sox_effect_handler_t const * input_handler(void){  static sox_effect_handler_t handler = {    "input", NULL, SOX_EFF_MCHAN, NULL, NULL, NULL, input_drain, NULL, NULL, 0  };  return &handler;} /* A `stub' effect handler to handle outputting samples from the effects * chain; the only function needed for this example is `flow' */static sox_effect_handler_t const * output_handler(void){  static sox_effect_handler_t handler = {    "output", NULL, SOX_EFF_MCHAN, NULL, NULL, output_flow, NULL, NULL, NULL, 0  };  return &handler;} /* * Reads input file, applies vol & flanger effects, stores in output file. * E.g. example1 monkey.au monkey.aiff */int main(int argc, char * argv[]){  sox_effects_chain_t * chain;  sox_effect_t * e;  char * vol[] = {"3dB"};   assert(argc == 3);   /* All libSoX applications must start by initialising the SoX library */  assert(sox_init() == SOX_SUCCESS);   /* Open the input file (with default parameters) */  assert((in = sox_open_read(argv[1], NULL, NULL, NULL)));   /* Open the output file; we must specify the output signal characteristics.   * Since we are using only simple effects, they are the same as the input   * file characteristics */  assert((out = sox_open_write(argv[2], &in->signal, NULL, NULL, NULL, NULL)));   /* Create an effects chain; some effects need to know about the input   * or output file encoding so we provide that information here */  chain = sox_create_effects_chain(&in->encoding, &out->encoding);   /* The first effect in the effect chain must be something that can source   * samples; in this case, we have defined an input handler that inputs   * data from an audio file */  e = sox_create_effect(input_handler());  /* This becomes the first `effect' in the chain */  assert(sox_add_effect(chain, e, &in->signal, &in->signal) == SOX_SUCCESS);  free(e);   /* Create the `vol' effect, and initialise it with the desired parameters: */  e = sox_create_effect(sox_find_effect("vol"));  assert(sox_effect_options(e, 1, vol) == SOX_SUCCESS);  /* Add the effect to the end of the effects processing chain: */  assert(sox_add_effect(chain, e, &in->signal, &in->signal) == SOX_SUCCESS);  free(e);   /* Create the `flanger' effect, and initialise it with default parameters: */  e = sox_create_effect(sox_find_effect("flanger"));  assert(sox_effect_options(e, 0, NULL) == SOX_SUCCESS);  /* Add the effect to the end of the effects processing chain: */  assert(sox_add_effect(chain, e, &in->signal, &in->signal) == SOX_SUCCESS);  free(e);   /* The last effect in the effect chain must be something that only consumes   * samples; in this case, we have defined an output handler that outputs   * data to an audio file */  e = sox_create_effect(output_handler());  assert(sox_add_effect(chain, e, &in->signal, &in->signal) == SOX_SUCCESS);  free(e);   /* Flow samples through the effects processing chain until EOF is reached */  sox_flow_effects(chain, NULL, NULL);   /* All done; tidy up: */  sox_delete_effects_chain(chain);  sox_close(out);  sox_close(in);  sox_quit();  return 0;}