/* libSoX file format: CVSD (see cvsd.c)        (c) 2007-8 SoX contributors * * 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 */ #include "cvsd.h" LSX_FORMAT_HANDLER(cvsd){  static char const * const names[] = {"cvsd", "cvs", NULL};  static unsigned const write_encodings[] = {SOX_ENCODING_CVSD, 1, 0, 0};  static sox_format_handler_t const handler = {SOX_LIB_VERSION_CODE,    "Headerless MIL Std 188 113 Continuously Variable Slope Delta modulation",    names, SOX_FILE_MONO,    lsx_cvsdstartread, lsx_cvsdread, lsx_cvsdstopread,    lsx_cvsdstartwrite, lsx_cvsdwrite, lsx_cvsdstopwrite,    lsx_rawseek, write_encodings, NULL, sizeof(cvsd_priv_t)  };  return &handler;} /* libSoX file format: CVU   (c) 2008 robs@users.sourceforge.net * Unfiltered, therefore, on decode, use with either filter -4k or rate 8k */ typedef struct {  double         sample, step, step_mult, step_add;  unsigned       last_n_bits;  unsigned char  byte;  off_t          bit_count;} priv_t; static int start(sox_format_t * ft){  priv_t *p = (priv_t *) ft->priv;   ft->signal.channels = 1;  lsx_rawstart(ft, sox_true, sox_false, sox_true, SOX_ENCODING_CVSD, 1);  p->last_n_bits = 5; /* 101 */  p->step_mult = exp((-1 / .005 / ft->signal.rate));  p->step_add = (1 - p->step_mult) * (.1 * SOX_SAMPLE_MAX);  lsx_debug("step_mult=%g step_add=%f", p->step_mult, p->step_add);  return SOX_SUCCESS;} static void decode(priv_t * p, int bit){  p->last_n_bits = ((p->last_n_bits << 1) | bit) & 7;   p->step *= p->step_mult;  if (p->last_n_bits == 0 || p->last_n_bits == 7)    p->step += p->step_add;   if (p->last_n_bits & 1)    p->sample = min(p->step_mult * p->sample + p->step, SOX_SAMPLE_MAX);  else    p->sample = max(p->step_mult * p->sample - p->step, SOX_SAMPLE_MIN);} static size_t cvsdread(sox_format_t * ft, sox_sample_t * buf, size_t len){  priv_t *p = (priv_t *) ft->priv;  size_t i;   for (i = 0; i < len; ++i) {    if (!(p->bit_count & 7))      if (lsx_read_b_buf(ft, &p->byte, (size_t)1) != 1)        break;    ++p->bit_count;    decode(p, p->byte & 1);    p->byte >>= 1;    *buf++ = floor(p->sample + .5);  }  return i;} static size_t cvsdwrite(sox_format_t * ft, sox_sample_t const * buf, size_t len){  priv_t *p = (priv_t *) ft->priv;  size_t i;   for (i = 0; i < len; ++i) {    decode(p, *buf++ > p->sample);    p->byte >>= 1;    p->byte |= p->last_n_bits << 7;    if (!(++p->bit_count & 7))      if (lsx_writeb(ft, p->byte) != SOX_SUCCESS)        break;  }  return len;} LSX_FORMAT_HANDLER(cvu){  static char const * const names[] = {"cvu", NULL};  static unsigned const write_encodings[] = {SOX_ENCODING_CVSD, 1, 0, 0};  static sox_format_handler_t const handler = {SOX_LIB_VERSION_CODE,    "Headerless Continuously Variable Slope Delta modulation (unfiltered)",    names, SOX_FILE_MONO, start, cvsdread, NULL, start, cvsdwrite, NULL,    lsx_rawseek, write_encodings, NULL, sizeof(priv_t)  };  return &handler;}