add example1.c

app/src/main/cpp/sox/example1.c

@@ -0,0 +1,167 @@
+/* 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;
+}