shithub: sox

ref: 8b4f02ed4de617adb9cab6ebac890882248271f7
dir: /src/pad.c/

/*  Sound Tools Effect: Pad With Silence
 *
 *  (c) 2006 robs@users.sourceforge.net
 *
 *  See LICENSE file for further copyright information.
 */

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

typedef struct pad
{
  int npads;         /* Number of pads requested */
  struct {
    char * str;      /* Comman-line argument to parse for this pad */
    st_size_t start; /* Start padding when in_pos equals this */
    st_size_t pad;   /* Number of samples to pad */
  } * pads;

  st_size_t in_pos;  /* Number of samples read from the input stream */
  int pads_pos;      /* Number of pads completed so far */
  st_size_t pad_pos; /* Number of samples through the current pad */
} * pad_t;

assert_static(sizeof(struct pad) <= ST_MAX_EFFECT_PRIVSIZE,
              /* else */ pad_PRIVSIZE_too_big);

static int parse(eff_t effp, char **argv, st_rate_t rate)
{
  pad_t p = (pad_t) effp->priv;
  char const * next;
  int i;

  for (i = 0; i < p->npads; ++i) {
    if (argv) /* 1st parse only */
      p->pads[i].str = xstrdup(argv[i]);
    next = st_parsesamples(rate, p->pads[i].str, &p->pads[i].pad, 't');
    if (next == NULL) break;
    if (*next == '\0')
      p->pads[i].start = i? ST_SIZE_MAX : 0;
    else {
      if (*next != '@') break;
      next = st_parsesamples(rate, next+1, &p->pads[i].start, 't');
      if (next == NULL || *next != '\0') break;
    }
    if (i > 0 && p->pads[i].start <= p->pads[i-1].start) break;
  }
  if (i < p->npads) {
    st_fail(effp->h->usage);
    return ST_EOF;
  }
  return ST_SUCCESS;
}

static int st_pad_getopts(eff_t effp, int n, char **argv)
{
  pad_t p = (pad_t) effp->priv;
  p->pads = xcalloc(p->npads = n, sizeof(*p->pads));
  return parse(effp, argv, ST_MAXRATE); /* No rate yet, parse with dummy */
}

static int st_pad_start(eff_t effp)
{
  pad_t p = (pad_t) effp->priv;
  int i;

  parse(effp, 0, effp->ininfo.rate); /* Re-parse now rate is known */
  p->in_pos = p->pad_pos = p->pads_pos = 0;
  for (i = 0; i < p->npads; ++i)
    if (p->pads[i].pad)
      return ST_SUCCESS;
  return ST_EFF_NULL;
}

static int st_pad_flow(eff_t effp, const st_sample_t * ibuf, st_sample_t * obuf, st_size_t * isamp, st_size_t * osamp)
{
  pad_t p = (pad_t) effp->priv;
  st_size_t c, idone = 0, odone = 0;
  *isamp /= effp->ininfo.channels;
  *osamp /= effp->ininfo.channels;

  do {
    /* Copying: */
    for (; idone < *isamp && odone < *osamp && !(p->pads_pos != p->npads && p->in_pos == p->pads[p->pads_pos].start); ++idone, ++odone, ++p->in_pos)
      for (c = 0; c < effp->ininfo.channels; ++c) *obuf++ = *ibuf++;

    /* Padding: */
    if (p->pads_pos != p->npads && p->in_pos == p->pads[p->pads_pos].start) {
      for (; odone < *osamp && p->pad_pos < p->pads[p->pads_pos].pad; ++odone, ++p->pad_pos)
        for (c = 0; c < effp->ininfo.channels; ++c) *obuf++ = 0;
      if (p->pad_pos == p->pads[p->pads_pos].pad) { /* Move to next pad? */
        ++p->pads_pos;
        p->pad_pos = 0;
      }
    }
  } while (idone < *isamp && odone < *osamp);

  *isamp = idone * effp->ininfo.channels;
  *osamp = odone * effp->ininfo.channels;
  return ST_SUCCESS;
}

static int st_pad_drain(eff_t effp, st_sample_t * obuf, st_size_t * osamp)
{
  static st_size_t isamp = 0;
  pad_t p = (pad_t) effp->priv;
  if (p->pads_pos != p->npads && p->in_pos != p->pads[p->pads_pos].start)
    p->in_pos = ST_SIZE_MAX;  /* Invoke the final pad (with no given start) */
  return st_pad_flow(effp, 0, obuf, &isamp, osamp);
}

static int st_pad_stop(eff_t effp)
{
  pad_t p = (pad_t) effp->priv;
  if (p->pads_pos != p->npads)
    st_warn("Input audio too short; pads not applied: %i",p->npads-p->pads_pos);
  /* Don't free stuff from getopts; start & stop must be symmetric */
  return ST_SUCCESS;
}

static st_effect_t st_pad_effect = {
  "pad",
  "Usage: pad {length[@position]}",
  ST_EFF_MCHAN,
  st_pad_getopts,
  st_pad_start,
  st_pad_flow,
  st_pad_drain,
  st_pad_stop
};

const st_effect_t *st_pad_effect_fn(void)
{
  return &st_pad_effect;
}