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FFmpeg/libavcodec/dpcm.c

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  1. /*

  2.  * Assorted DPCM codecs

  3.  * Copyright (c) 2003 The ffmpeg Project.

  4.  *

  5.  * This library is free software; you can redistribute it and/or

  6.  * modify it under the terms of the GNU Lesser General Public

  7.  * License as published by the Free Software Foundation; either

  8.  * version 2 of the License, or (at your option) any later version.

  9.  *

  10.  * This library is distributed in the hope that it will be useful,

  11.  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  12.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

  13.  * Lesser General Public License for more details.

  14.  *

  15.  * You should have received a copy of the GNU Lesser General Public

  16.  * License along with this library; if not, write to the Free Software

  17.  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

  18.  */

  19. 

  20. /**

  21.  * @file: dpcm.c

  22.  * Assorted DPCM (differential pulse code modulation) audio codecs

  23.  * by Mike Melanson (melanson@pcisys.net)

  24.  * Xan DPCM decoder by Mario Brito (mbrito@student.dei.uc.pt)

  25.  * for more information on the specific data formats, visit:

  26.  *   http://www.pcisys.net/~melanson/codecs/simpleaudio.html

  27.  *

  28.  * Note about using the Xan DPCM decoder: Xan DPCM is used in AVI files

  29.  * found in the Wing Commander IV computer game. These AVI files contain

  30.  * WAVEFORMAT headers which report the audio format as 0x01: raw PCM.

  31.  * Clearly incorrect. To detect Xan DPCM, you will probably have to

  32.  * special-case your AVI demuxer to use Xan DPCM if the file uses 'Xxan'

  33.  * (Xan video) for its video codec. Alternately, such AVI files also contain

  34.  * the fourcc 'Axan' in the 'auds' chunk of the AVI header.

  35.  */

  36. 

  37. #include "avcodec.h"

  38. 

  39. typedef struct DPCMContext {

  40.     int channels;

  41.     short roq_square_array[256];

  42. } DPCMContext;

  43. 

  44. #define SATURATE_S16(x)  if (x < -32768) x = -32768; \

  45.   else if (x > 32767) x = 32767;

  46. #define SE_16BIT(x)  if (x & 0x8000) x -= 0x10000;

  47. 

  48. static int interplay_delta_table[] = {

  49.          0,      1,      2,      3,      4,      5,      6,      7,

  50.          8,      9,     10,     11,     12,     13,     14,     15,

  51.         16,     17,     18,     19,     20,     21,     22,     23,

  52.         24,     25,     26,     27,     28,     29,     30,     31,

  53.         32,     33,     34,     35,     36,     37,     38,     39,

  54.         40,     41,     42,     43,     47,     51,     56,     61,

  55.         66,     72,     79,     86,     94,    102,    112,    122,

  56.        133,    145,    158,    173,    189,    206,    225,    245,

  57.        267,    292,    318,    348,    379,    414,    452,    493,

  58.        538,    587,    640,    699,    763,    832,    908,    991,

  59.       1081,   1180,   1288,   1405,   1534,   1673,   1826,   1993,

  60.       2175,   2373,   2590,   2826,   3084,   3365,   3672,   4008,

  61.       4373,   4772,   5208,   5683,   6202,   6767,   7385,   8059,

  62.       8794,   9597,  10472,  11428,  12471,  13609,  14851,  16206,

  63.      17685,  19298,  21060,  22981,  25078,  27367,  29864,  32589,

  64.     -29973, -26728, -23186, -19322, -15105, -10503,  -5481,     -1,

  65.          1,      1,   5481,  10503,  15105,  19322,  23186,  26728,

  66.      29973, -32589, -29864, -27367, -25078, -22981, -21060, -19298,

  67.     -17685, -16206, -14851, -13609, -12471, -11428, -10472,  -9597,

  68.      -8794,  -8059,  -7385,  -6767,  -6202,  -5683,  -5208,  -4772,

  69.      -4373,  -4008,  -3672,  -3365,  -3084,  -2826,  -2590,  -2373,

  70.      -2175,  -1993,  -1826,  -1673,  -1534,  -1405,  -1288,  -1180,

  71.      -1081,   -991,   -908,   -832,   -763,   -699,   -640,   -587,

  72.       -538,   -493,   -452,   -414,   -379,   -348,   -318,   -292,

  73.       -267,   -245,   -225,   -206,   -189,   -173,   -158,   -145,

  74.       -133,   -122,   -112,   -102,    -94,    -86,    -79,    -72,

  75.        -66,    -61,    -56,    -51,    -47,    -43,    -42,    -41,

  76.        -40,    -39,    -38,    -37,    -36,    -35,    -34,    -33,

  77.        -32,    -31,    -30,    -29,    -28,    -27,    -26,    -25,

  78.        -24,    -23,    -22,    -21,    -20,    -19,    -18,    -17,

  79.        -16,    -15,    -14,    -13,    -12,    -11,    -10,     -9,

  80.         -8,     -7,     -6,     -5,     -4,     -3,     -2,     -1

  81. 

  82. };

  83. 

  84. static int dpcm_decode_init(AVCodecContext *avctx)

  85. {

  86.     DPCMContext *s = avctx->priv_data;

  87.     int i;

  88.     short square;

  89. 

  90.     s->channels = avctx->channels;

  91. 

  92.     switch(avctx->codec->id) {

  93. 

  94.     case CODEC_ID_ROQ_DPCM:

  95.         /* initialize square table */

  96.         for (i = 0; i < 128; i++) {

  97.             square = i * i;

  98.             s->roq_square_array[i] = square;

  99.             s->roq_square_array[i + 128] = -square;

  100.         }

  101.         break;

  102. 

  103.     default:

  104.         break;

  105.     }

  106. 

  107.     return 0;

  108. }

  109. 

  110. static int dpcm_decode_frame(AVCodecContext *avctx,

  111.                              void *data, int *data_size,

  112.                              uint8_t *buf, int buf_size)

  113. {

  114.     DPCMContext *s = avctx->priv_data;

  115.     int in, out = 0;

  116.     int predictor[2];

  117.     int channel_number = 0;

  118.     short *output_samples = data;

  119.     int shift[2];

  120.     unsigned char byte;

  121.     short diff;

  122. 

  123.     if (!buf_size)

  124.         return 0;

  125. 

  126.     switch(avctx->codec->id) {

  127. 

  128.     case CODEC_ID_ROQ_DPCM:

  129.         if (s->channels == 1)

  130.             predictor[0] = LE_16(&buf[6]);

  131.         else {

  132.             predictor[0] = buf[7] << 8;

  133.             predictor[1] = buf[6] << 8;

  134.         }

  135.         SE_16BIT(predictor[0]);

  136.         SE_16BIT(predictor[1]);

  137. 

  138.         /* decode the samples */

  139.         for (in = 8, out = 0; in < buf_size; in++, out++) {

  140.             predictor[channel_number] += s->roq_square_array[buf[in]];

  141.             SATURATE_S16(predictor[channel_number]);

  142.             output_samples[out] = predictor[channel_number];

  143. 

  144.             /* toggle channel */

  145.             channel_number ^= s->channels - 1;

  146.         }

  147.         break;

  148. 

  149.     case CODEC_ID_INTERPLAY_DPCM:

  150.         in = 6;  /* skip over the stream mask and stream length */

  151.         predictor[0] = LE_16(&buf[in]);

  152.         in += 2;

  153.         SE_16BIT(predictor[0])

  154.         output_samples[out++] = predictor[0];

  155.         if (s->channels == 2) {

  156.             predictor[1] = LE_16(&buf[in]);

  157.             in += 2;

  158.             SE_16BIT(predictor[1])

  159.             output_samples[out++] = predictor[1];

  160.         }

  161. 

  162.         while (in < buf_size) {

  163.             predictor[channel_number] += interplay_delta_table[buf[in++]];

  164.             SATURATE_S16(predictor[channel_number]);

  165.             output_samples[out++] = predictor[channel_number];

  166. 

  167.             /* toggle channel */

  168.             channel_number ^= s->channels - 1;

  169.         }

  170. 

  171.         break;

  172. 

  173.     case CODEC_ID_XAN_DPCM:

  174.         in = 0;

  175.         shift[0] = shift[1] = 4;

  176.         predictor[0] = LE_16(&buf[in]);

  177.         in += 2;

  178.         SE_16BIT(predictor[0]);

  179.         if (s->channels == 2) {

  180.             predictor[1] = LE_16(&buf[in]);

  181.             in += 2;

  182.             SE_16BIT(predictor[1]);

  183.         }

  184. 

  185.         while (in < buf_size) {

  186.             byte = buf[in++];

  187.             diff = (byte & 0xFC) << 8;

  188.             if ((byte & 0x03) == 3)

  189.                 shift[channel_number]++;

  190.             else

  191.                 shift[channel_number] -= (2 * (byte & 3));

  192.             /* saturate the shifter to a lower limit of 0 */

  193.             if (shift[channel_number] < 0)

  194.                 shift[channel_number] = 0;

  195. 

  196.             diff >>= shift[channel_number];

  197.             predictor[channel_number] += diff;

  198. 

  199.             SATURATE_S16(predictor[channel_number]);

  200.             output_samples[out++] = predictor[channel_number];

  201. 

  202.             /* toggle channel */

  203.             channel_number ^= s->channels - 1;

  204.         }

  205.         break;

  206.     }

  207. 

  208.     *data_size = out * sizeof(short);

  209.     return buf_size;

  210. }

  211. 

  212. AVCodec roq_dpcm_decoder = {

  213.     "roq_dpcm",

  214.     CODEC_TYPE_AUDIO,

  215.     CODEC_ID_ROQ_DPCM,

  216.     sizeof(DPCMContext),

  217.     dpcm_decode_init,

  218.     NULL,

  219.     NULL,

  220.     dpcm_decode_frame,

  221. };

  222. 

  223. AVCodec interplay_dpcm_decoder = {

  224.     "interplay_dpcm",

  225.     CODEC_TYPE_AUDIO,

  226.     CODEC_ID_INTERPLAY_DPCM,

  227.     sizeof(DPCMContext),

  228.     dpcm_decode_init,

  229.     NULL,

  230.     NULL,

  231.     dpcm_decode_frame,

  232. };

  233. 

  234. AVCodec xan_dpcm_decoder = {

  235.     "xan_dpcm",

  236.     CODEC_TYPE_AUDIO,

  237.     CODEC_ID_XAN_DPCM,

  238.     sizeof(DPCMContext),

  239.     dpcm_decode_init,

  240.     NULL,

  241.     NULL,

  242.     dpcm_decode_frame,

  243. };