shithub: sox

ref: ffc11e800e271c0ed38284fdd114507253c7112d
dir: /src/crop.c/

/* libSoX effect: Crop ends of audio   (c) 2009 robs@users.sourceforge.net
 *
 * 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 2.1 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,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

/* This is W.I.P. hence marked SOX_EFF_DEPRECATED for now.
 * Need to change uint32_t/INT32_MAX to uint64_t/INT64_MAX (for LFS) and do
 * proper length change tracking through the effects chain.
 */

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

typedef struct {
  int argc;
  struct {sox_bool from_end; char * str; uint32_t at;} pos[2];
} priv_t;

#if 0
uint64_t sox_crop_get_start(sox_effect_t * effp)
{
  priv_t * p = (priv_t *)effp->priv;
  return p->pos[0].at;
}

void sox_crop_clear_start(sox_effect_t * effp)
{
  priv_t * p = (priv_t *)effp->priv;
  p->pos[0].at = 0;
}
#endif

static int parse(sox_effect_t * effp, char * * argv, sox_rate_t rate)
{
  priv_t * p = (priv_t *)effp->priv;
  char const * s;
  int i;

  for (i = p->argc - 1; i == 0 || i == 1; --i) {
    if (argv) /* 1st parse only */
      p->pos[i].str = lsx_strdup(argv[i]);
    s = p->pos[i].str;
    if (*s == '-') {
      p->pos[i].from_end = sox_true;
      ++s;
    }
    if (!lsx_parsesamples(rate, s, &p->pos[i].at, 't'))
      break;
  }
  return i >= 0 ? lsx_usage(effp) : SOX_SUCCESS;
}

static int create(sox_effect_t * effp, int argc, char * * argv)
{
  priv_t * p = (priv_t *)effp->priv;
  --argc, ++argv;
  p->argc = argc;
  return parse(effp, argv, 1e5); /* No rate yet; parse with dummy */
}

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

  p->pos[1].at = INT32_MAX;
  parse(effp, 0, effp->in_signal.rate); /* Re-parse now rate is known */
  for (i = 0; i < 2; ++i) {
    p->pos[i].at *= effp->in_signal.channels;
    if (p->pos[i].from_end) {
      if (effp->in_signal.length == SOX_UNSPEC) {
        lsx_fail("cannot crop from end: audio length is not known");
        return SOX_EOF;
      }
      if (p->pos[i].at > effp->in_signal.length) {
        lsx_fail("cannot crop that much from end: audio is too short");
        return SOX_EOF;
      }
      p->pos[i].at = effp->in_signal.length - p->pos[i].at;
    }
  }
  if (p->pos[0].at > p->pos[1].at) {
    lsx_fail("start position must be less than stop position");
    return SOX_EOF;
  }
  if (!(p->pos[1].at -= p->pos[0].at))
    p->pos[0].at = 0;
  return p->pos[0].at || p->pos[1].at != effp->in_signal.length ? SOX_SUCCESS : SOX_EFF_NULL;
}

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

  p->pos[0].at -= skipped = min(p->pos[0].at, *isamp);
  *osamp = !p->pos[0].at * min(p->pos[1].at, min(*isamp - skipped, *osamp));
  memcpy(obuf, ibuf + skipped, *osamp * sizeof(*obuf));
  *isamp = skipped + *osamp;
  return (p->pos[1].at -= *osamp) ? SOX_SUCCESS : SOX_EOF;
}

static int stop(sox_effect_t * effp)
{
  priv_t * p = (priv_t *)effp->priv;
  if (p->pos[0].at || (p->pos[1].at && p->argc == 2))
    lsx_warn("input audio too short to crop as requested");
  return SOX_SUCCESS;
}

static int kill(sox_effect_t * effp)
{
  priv_t * p = (priv_t *)effp->priv;
  free(p->pos[0].str);
  free(p->pos[1].str);
  return SOX_SUCCESS;
}

sox_effect_handler_t const * lsx_crop_effect_fn(void)
{
  static sox_effect_handler_t handler = {
    "crop", "before [from]",
    SOX_EFF_MCHAN | /* SOX_EFF_LENGTH | */ SOX_EFF_MODIFY | SOX_EFF_DEPRECATED,
    create, start, flow, NULL, stop, kill, sizeof(priv_t)
  };
  return &handler;
}