src/adpcm.h

   1 /* adpcm.h  codex functions for MS_ADPCM data
   2  *          (hopefully) provides interoperability with
   3  *          Microsoft's ADPCM format, but, as usual,
   4  *          see LACK-OF-WARRANTY information below.
   5  *
   6  *      Copyright (C) 1999 Stanley J. Brooks <stabro@megsinet.net>
   7  *
   8  * This library is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or (at
  11  * your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful, but
  14  * WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser
  16  * General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this library; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  21  *
  22  */
  23 #include "sox.h"
  24
  25 #ifndef SAMPL
  26 #define SAMPL short
  27 #endif
  28
  29 /* default coef sets */
  30 extern const short lsx_ms_adpcm_i_coef[7][2];
  31
  32 /* lsx_ms_adpcm_block_expand_i() outputs interleaved samples into one output buffer */
  33 extern const char *lsx_ms_adpcm_block_expand_i(
  34         unsigned chans,          /* total channels             */
  35         int nCoef,
  36         const short *coef,
  37         const unsigned char *ibuff,/* input buffer[blockAlign]   */
  38         SAMPL *obuff,       /* output samples, n*chans    */
  39         int n               /* samples to decode PER channel, REQUIRE n % 8 == 1  */
  40 );
  41
  42 extern void lsx_ms_adpcm_block_mash_i(
  43         unsigned chans,          /* total channels */
  44         const SAMPL *ip,    /* ip[n*chans] is interleaved input samples */
  45         int n,              /* samples to encode PER channel, REQUIRE */
  46         int *st,            /* input/output steps, 16<=st[i] */
  47         unsigned char *obuff,      /* output buffer[blockAlign] */
  48         int blockAlign      /* >= 7*chans + n/2          */
  49 );
  50
  51 /* Some helper functions for computing samples/block and blockalign */
  52
  53 /*
  54  * lsx_ms_adpcm_samples_in(dataLen, chans, blockAlign, samplesPerBlock)
  55  *  returns the number of samples/channel which would be
  56  *  in the dataLen, given the other parameters ...
  57  *  if input samplesPerBlock is 0, then returns the max
  58  *  samplesPerBlock which would go into a block of size blockAlign
  59  *  Yes, it is confusing usage.
  60  */
  61 extern size_t lsx_ms_adpcm_samples_in(
  62         size_t dataLen,
  63         size_t chans,
  64         size_t blockAlign,
  65         size_t samplesPerBlock
  66 );
  67
  68 /*
  69  * size_t lsx_ms_adpcm_bytes_per_block(chans, samplesPerBlock)
  70  *   return minimum blocksize which would be required
  71  *   to encode number of chans with given samplesPerBlock
  72  */
  73 extern size_t lsx_ms_adpcm_bytes_per_block(
  74         size_t chans,
  75         size_t samplesPerBlock
  76 );