shithub: sox

ref: f92e29d995bbb207eff1bbaa08f75a66ea5b8398
dir: /src/normalise.c/

/*
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 *
 * This library 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 Lesser
 * General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, write to the Free Software Foundation,
 * Fifth Floor, 51 Franklin Street, Boston, MA 02111-1301, USA.
 */

/* Effect: Normalise   (c) 2008 robs@users.sourceforge.net */

#include "sox_i.h"
#include <math.h>
#include <string.h>

typedef struct norm {
  double        norm0;    /* Multiplier to take to 0dB FSD */
  double        level;    /* Multiplier to take to 'level' */
  sox_sample_t  min, max;
  FILE          * tmp_file;
} * priv_t;

assert_static(sizeof(struct norm) <= SOX_MAX_EFFECT_PRIVSIZE,
              /* else */ norm_PRIVSIZE_too_big);

static int create(sox_effect_t * effp, int argc, char * * argv)
{
  priv_t p = (priv_t)effp->priv;
  char dummy;

  if (argc > 1 || (argc == 1 &&
        (sscanf(*argv, "%lf%c", &p->level, &dummy) != 1 || p->level > 0)))
    return sox_usage(effp);
  p->level = dB_to_linear(p->level);
  return SOX_SUCCESS;
}

static int start(sox_effect_t * effp)
{
  priv_t p = (priv_t)effp->priv;

  p->norm0 = p->max = p->min = 0;
  p->tmp_file = tmpfile();
  if (p->tmp_file == NULL) {
    sox_fail("can't create temporary file: %s", strerror(errno));
    return SOX_EOF;
  }
  return SOX_SUCCESS;
}

static int flow(sox_effect_t * effp, const sox_sample_t * ibuf,
    sox_sample_t * obuf, sox_size_t * isamp, sox_size_t * osamp)
{
  priv_t p = (priv_t)effp->priv;
  sox_size_t len;

  if (fwrite(ibuf, sizeof(*ibuf), *isamp, p->tmp_file) != *isamp) {
    sox_fail("error writing temporary file: %s", strerror(errno));
    return SOX_EOF;
  }
  for (len = *osamp; len; --len, ++ibuf) {
    p->max = max(p->max, *ibuf);
    p->min = min(p->min, *ibuf);
  }
  (void)obuf, *osamp = 0; /* samples not output until drain */
  return SOX_SUCCESS;
}

static int drain(sox_effect_t * effp, sox_sample_t * obuf, sox_size_t * osamp)
{
  priv_t p = (priv_t)effp->priv;
  sox_size_t len;
  int result = SOX_SUCCESS;

  if (!p->norm0) {
    int shift_for_max = (4 - min(effp->outinfo.size, 4)) << 3;
    double max = (SOX_SAMPLE_MAX >> shift_for_max) << shift_for_max;
    p->norm0 = p->level * min(max / p->max, (double)SOX_SAMPLE_MIN / p->min);
    rewind(p->tmp_file);
  }
  len = fread(obuf, sizeof(*obuf), *osamp, p->tmp_file);
  if (len != *osamp && !feof(p->tmp_file)) {
    sox_fail("error reading temporary file: %s", strerror(errno));
    result = SOX_EOF;
  }
  for (*osamp = len; len; --len, ++obuf)
    *obuf = floor(*obuf * p->norm0 + .5);
  return result;
}

static int stop(sox_effect_t * effp)
{
  priv_t p = (priv_t)effp->priv;

  fclose(p->tmp_file); /* auto-deleted by tmpfile */
  return SOX_SUCCESS;
}

sox_effect_handler_t const * sox_norm_effect_fn(void)
{
  static sox_effect_handler_t handler = {
    "norm", "[level]", 0, create, start, flow, drain, stop, NULL
  };
  return &handler;
}