gst/mve/mveaudiodec.c

/*
 * Copyright (c) 2003 The ffmpeg Project, Mike Melanson
 *
 * 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, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * Interplay compressed audio codec by Mike Melanson (melanson@pcisys.net)
 */

#include <gst/gst.h>

static const short delta_table[256] = {
  0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
  16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
  32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 47, 51, 56, 61,
  66, 72, 79, 86, 94, 102, 112, 122, 133, 145, 158, 173, 189, 206, 225, 245,
  267, 292, 318, 348, 379, 414, 452, 493, 538, 587, 640, 699, 763, 832, 908,
  991,
  1081, 1180, 1288, 1405, 1534, 1673, 1826, 1993, 2175, 2373, 2590, 2826, 3084,
  3365, 3672, 4008,
  4373, 4772, 5208, 5683, 6202, 6767, 7385, 8059, 8794, 9597, 10472, 11428,
  12471, 13609, 14851, 16206,
  17685, 19298, 21060, 22981, 25078, 27367, 29864, 32589, -29973, -26728,
  -23186, -19322, -15105, -10503, -5481, -1,
  1, 1, 5481, 10503, 15105, 19322, 23186, 26728, 29973, -32589, -29864, -27367,
  -25078, -22981, -21060, -19298,
  -17685, -16206, -14851, -13609, -12471, -11428, -10472, -9597, -8794, -8059,
  -7385, -6767, -6202, -5683, -5208, -4772,
  -4373, -4008, -3672, -3365, -3084, -2826, -2590, -2373, -2175, -1993, -1826,
  -1673, -1534, -1405, -1288, -1180,
  -1081, -991, -908, -832, -763, -699, -640, -587, -538, -493, -452, -414, -379,
  -348, -318, -292,
  -267, -245, -225, -206, -189, -173, -158, -145, -133, -122, -112, -102, -94,
  -86, -79, -72,
  -66, -61, -56, -51, -47, -43, -42, -41, -40, -39, -38, -37, -36, -35, -34,
  -33,
  -32, -31, -30, -29, -28, -27, -26, -25, -24, -23, -22, -21, -20, -19, -18,
  -17,
  -16, -15, -14, -13, -12, -11, -10, -9, -8, -7, -6, -5, -4, -3, -2, -1
};

void
ipaudio_uncompress (short *buffer, unsigned short buf_len,
    const unsigned char *data, unsigned char channels)
{
  int i, out = 0;
  int predictor[2];
  int channel_number = 0;

  for (i = 0; i < channels; ++i) {
    predictor[i] = GST_READ_UINT16_LE (data);
    data += 2;
    if (predictor[i] & 0x8000)
      predictor[i] -= 0x10000;
    buffer[out++] = predictor[i];
  }

  /* we count in 16-bit ints, so adjust the buffer size */
  buf_len /= 2;
  while (out < buf_len) {
    predictor[channel_number] += delta_table[*data++];
    if (predictor[channel_number] < -32768)
      predictor[channel_number] = -32768;
    else if (predictor[channel_number] > 32767)
      predictor[channel_number] = 32767;
    buffer[out++] = predictor[channel_number];

    /* toggle channel */
    channel_number ^= channels - 1;
  }
}