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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. #define LE_16(x)  ((((uint8_t*)(x))[1] << 8) | ((uint8_t*)(x))[0])

  48. #define LE_32(x)  ((((uint8_t*)(x))[3] << 24) | \

  49.                    (((uint8_t*)(x))[2] << 16) | \

  50.                    (((uint8_t*)(x))[1] << 8) | \

  51.                     ((uint8_t*)(x))[0])

  52. 

  53. static int interplay_delta_table[] = {

  54.          0,      1,      2,      3,      4,      5,      6,      7,

  55.          8,      9,     10,     11,     12,     13,     14,     15,

  56.         16,     17,     18,     19,     20,     21,     22,     23,

  57.         24,     25,     26,     27,     28,     29,     30,     31,

  58.         32,     33,     34,     35,     36,     37,     38,     39,

  59.         40,     41,     42,     43,     47,     51,     56,     61,

  60.         66,     72,     79,     86,     94,    102,    112,    122,

  61.        133,    145,    158,    173,    189,    206,    225,    245,

  62.        267,    292,    318,    348,    379,    414,    452,    493,

  63.        538,    587,    640,    699,    763,    832,    908,    991,

  64.       1081,   1180,   1288,   1405,   1534,   1673,   1826,   1993,

  65.       2175,   2373,   2590,   2826,   3084,   3365,   3672,   4008,

  66.       4373,   4772,   5208,   5683,   6202,   6767,   7385,   8059,

  67.       8794,   9597,  10472,  11428,  12471,  13609,  14851,  16206,

  68.      17685,  19298,  21060,  22981,  25078,  27367,  29864,  32589,

  69.     -29973, -26728, -23186, -19322, -15105, -10503,  -5481,     -1,

  70.          1,      1,   5481,  10503,  15105,  19322,  23186,  26728,

  71.      29973, -32589, -29864, -27367, -25078, -22981, -21060, -19298,

  72.     -17685, -16206, -14851, -13609, -12471, -11428, -10472,  -9597,

  73.      -8794,  -8059,  -7385,  -6767,  -6202,  -5683,  -5208,  -4772,

  74.      -4373,  -4008,  -3672,  -3365,  -3084,  -2826,  -2590,  -2373,

  75.      -2175,  -1993,  -1826,  -1673,  -1534,  -1405,  -1288,  -1180,

  76.      -1081,   -991,   -908,   -832,   -763,   -699,   -640,   -587,

  77.       -538,   -493,   -452,   -414,   -379,   -348,   -318,   -292,

  78.       -267,   -245,   -225,   -206,   -189,   -173,   -158,   -145,

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

  80.        -66,    -61,    -56,    -51,    -47,    -43,    -42,    -41,

  81.        -40,    -39,    -38,    -37,    -36,    -35,    -34,    -33,

  82.        -32,    -31,    -30,    -29,    -28,    -27,    -26,    -25,

  83.        -24,    -23,    -22,    -21,    -20,    -19,    -18,    -17,

  84.        -16,    -15,    -14,    -13,    -12,    -11,    -10,     -9,

  85.         -8,     -7,     -6,     -5,     -4,     -3,     -2,     -1

  86. 

  87. };

  88. 

  89. static int dpcm_decode_init(AVCodecContext *avctx)

  90. {

  91.     DPCMContext *s = avctx->priv_data;

  92.     int i;

  93.     short square;

  94. 

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

  96. 

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

  98. 

  99.     case CODEC_ID_ROQ_DPCM:

  100.         /* initialize square table */

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

  102.             square = i * i;

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

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

  105.         }

  106.         break;

  107. 

  108.     default:

  109.         break;

  110.     }

  111. 

  112.     return 0;

  113. }

  114. 

  115. static int dpcm_decode_frame(AVCodecContext *avctx,

  116.                              void *data, int *data_size,

  117.                              uint8_t *buf, int buf_size)

  118. {

  119.     DPCMContext *s = avctx->priv_data;

  120.     int in, out = 0;

  121.     int predictor[2];

  122.     int channel_number = 0;

  123.     short *output_samples = data;

  124.     int shift[2];

  125.     unsigned char byte;

  126.     short diff;

  127. 

  128.     if (!buf_size)

  129.         return 0;

  130. 

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

  132. 

  133.     case CODEC_ID_ROQ_DPCM:

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

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

  136.         else {

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

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

  139.         }

  140.         SE_16BIT(predictor[0]);

  141.         SE_16BIT(predictor[1]);

  142. 

  143.         /* decode the samples */

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

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

  146.             SATURATE_S16(predictor[channel_number]);

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

  148. 

  149.             /* toggle channel */

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

  151.         }

  152.         break;

  153. 

  154.     case CODEC_ID_INTERPLAY_DPCM:

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

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

  157.         in += 2;

  158.         SE_16BIT(predictor[0])

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

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

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

  162.             in += 2;

  163.             SE_16BIT(predictor[1])

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

  165.         }

  166. 

  167.         while (in < buf_size) {

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

  169.             SATURATE_S16(predictor[channel_number]);

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

  171. 

  172.             /* toggle channel */

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

  174.         }

  175. 

  176.         break;

  177. 

  178.     case CODEC_ID_XAN_DPCM:

  179.         in = 0;

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

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

  182.         in += 2;

  183.         SE_16BIT(predictor[0]);

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

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

  186.             in += 2;

  187.             SE_16BIT(predictor[1]);

  188.         }

  189. 

  190.         while (in < buf_size) {

  191.             byte = buf[in++];

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

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

  194.                 shift[channel_number]++;

  195.             else

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

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

  198.             if (shift[channel_number] < 0)

  199.                 shift[channel_number] = 0;

  200. 

  201.             diff >>= shift[channel_number];

  202.             predictor[channel_number] += diff;

  203. 

  204.             SATURATE_S16(predictor[channel_number]);

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

  206. 

  207.             /* toggle channel */

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

  209.         }

  210.         break;

  211.     }

  212. 

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

  214.     return buf_size;

  215. }

  216. 

  217. AVCodec roq_dpcm_decoder = {

  218.     "roq_dpcm",

  219.     CODEC_TYPE_AUDIO,

  220.     CODEC_ID_ROQ_DPCM,

  221.     sizeof(DPCMContext),

  222.     dpcm_decode_init,

  223.     NULL,

  224.     NULL,

  225.     dpcm_decode_frame,

  226. };

  227. 

  228. AVCodec interplay_dpcm_decoder = {

  229.     "interplay_dpcm",

  230.     CODEC_TYPE_AUDIO,

  231.     CODEC_ID_INTERPLAY_DPCM,

  232.     sizeof(DPCMContext),

  233.     dpcm_decode_init,

  234.     NULL,

  235.     NULL,

  236.     dpcm_decode_frame,

  237. };

  238. 

  239. AVCodec xan_dpcm_decoder = {

  240.     "xan_dpcm",

  241.     CODEC_TYPE_AUDIO,

  242.     CODEC_ID_XAN_DPCM,

  243.     sizeof(DPCMContext),

  244.     dpcm_decode_init,

  245.     NULL,

  246.     NULL,

  247.     dpcm_decode_frame,

  248. };