shithub: sox

ref: 00a8871df8151ba4ce8355fa702c78cc129032a8
dir: /src/amr.h/

/*
 * File format: AMR   (c) 2007 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 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.
 */

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

typedef struct amr
{
  void * state;
  unsigned mode;
  short pcm[AMR_FRAME];
  sox_size_t pcm_index;
} * amr_t;

assert_static(sizeof(struct amr) <= SOX_MAX_FILE_PRIVSIZE, AMR_PRIV_TOO_BIG);

static sox_size_t decode_1_frame(ft_t ft)
{
  amr_t amr = (amr_t) ft->priv;
  int block_size_1;
  unsigned char coded[AMR_CODED_MAX];

  if (fread(coded, sizeof(coded[0]), 1, ft->fp) != 1)
    return AMR_FRAME;
  block_size_1 = block_size[(coded[0] >> 3) & 0x0F] - 1;
  if (fread(&coded[1], sizeof(coded[1]), block_size_1, ft->fp) != block_size_1)
    return AMR_FRAME;
  D_IF_decode(amr->state, coded, amr->pcm, 0);
  return 0;
}

static void encode_1_frame(ft_t ft)
{
  amr_t amr = (amr_t) ft->priv;
  unsigned char coded[AMR_CODED_MAX];
  fwrite(coded, 1, (unsigned)E_IF_encode(amr->state, amr->mode, amr->pcm, coded, 1), ft->fp);
}

static void set_format(ft_t ft)
{
  ft->signal.rate = AMR_RATE;
  ft->signal.size = SOX_SIZE_16BIT;
  ft->signal.encoding = AMR_ENCODING;
  ft->signal.channels = 1;
}

static int startread(ft_t ft)
{
  amr_t amr = (amr_t) ft->priv;
  char buffer[sizeof(magic)];

  amr->pcm_index = AMR_FRAME;

  amr->state = D_IF_init();

  fread(buffer, sizeof(char), sizeof(buffer) - 1, ft->fp);
  buffer[sizeof(buffer) - 1] = 0;
  if (strcmp(buffer, magic)) {
    sox_fail("Invalid magic number");
    return SOX_EOF;
  }
  set_format(ft);
  return SOX_SUCCESS;
}

static sox_size_t read(ft_t ft, sox_ssample_t * buf, sox_size_t len)
{
  amr_t amr = (amr_t) ft->priv;
  sox_size_t done;

  for (done = 0; done < len; done++) {
    if (amr->pcm_index >= AMR_FRAME)
      amr->pcm_index = decode_1_frame(ft);
    if (amr->pcm_index >= AMR_FRAME)
      break;
    *buf++ = SOX_SIGNED_16BIT_TO_SAMPLE(amr->pcm[amr->pcm_index++], ft->clips);
  }
  return done;
}

static int stopread(ft_t ft)
{
  amr_t amr = (amr_t) ft->priv;
  D_IF_exit(amr->state);
  return SOX_SUCCESS;
}

static int startwrite(ft_t ft)
{
  amr_t amr = (amr_t) ft->priv;

  if (ft->signal.compression != HUGE_VAL) {
    amr->mode = ft->signal.compression;
    if (amr->mode != ft->signal.compression || amr->mode > AMR_MODE_MAX) {
      sox_fail_errno(ft, SOX_EINVAL, "compression level must be a whole number from 0 to %i", AMR_MODE_MAX);
      return SOX_EOF;
    }
  }
  else amr->mode = 0;

  set_format(ft);
  amr->state = E_IF_init();
  sox_writes(ft, magic);
  amr->pcm_index = 0;
  return SOX_SUCCESS;
}

static sox_size_t write(ft_t ft, const sox_ssample_t * buf, sox_size_t len)
{
  amr_t amr = (amr_t) ft->priv;
  sox_size_t done;

  for (done = 0; done < len; ++done) {
    amr->pcm[amr->pcm_index++] = SOX_SAMPLE_TO_SIGNED_16BIT(*buf++, ft->clips);
    if (amr->pcm_index == AMR_FRAME) {
      amr->pcm_index = 0;
      encode_1_frame(ft);
    }
  }
  return done;
}

static int stopwrite(ft_t ft)
{
  amr_t amr = (amr_t) ft->priv;

  if (amr->pcm_index) {
    do {
      amr->pcm[amr->pcm_index++] = 0;
    } while (amr->pcm_index < AMR_FRAME);
    encode_1_frame(ft);
  }
  E_IF_exit(amr->state);
  return SOX_SUCCESS;
}

const sox_format_t *AMR_FORMAT_FN(void);

const sox_format_t *AMR_FORMAT_FN(void)
{
  static char const * names[] = {AMR_NAMES, NULL};
  static sox_format_t driver = {
    names, 0,
    startread, read, stopread,
    startwrite, write, stopwrite,
    sox_format_nothing_seek
  };
  return &driver;
}