codecs/codec_adpcm.c

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Based on frompcm.c and topcm.c from the Emiliano MIPL browser/
   5  * interpreter.  See http://www.bsdtelephony.com.mx
   6  *
   7  * Copyright (c) 2001 - 2005 Digium, Inc.
   8  * All rights reserved.
   9  *
  10  * Karl Sackett <krs@linux-support.net>, 2001-03-21
  11  *
  12  * See http://www.asterisk.org for more information about
  13  * the Asterisk project. Please do not directly contact
  14  * any of the maintainers of this project for assistance;
  15  * the project provides a web site, mailing lists and IRC
  16  * channels for your use.
  17  *
  18  * This program is free software, distributed under the terms of
  19  * the GNU General Public License Version 2. See the LICENSE file
  20  * at the top of the source tree.
  21  */
  22
  23 /*! \file
  24  *
  25  * \brief codec_adpcm.c - translate between signed linear and Dialogic ADPCM
  26  *
  27  * \ingroup codecs
  28  */
  29
  30 #include "asterisk.h"
  31
  32 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  33
  34 #include <fcntl.h>
  35 #include <netinet/in.h>
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <string.h>
  39 #include <unistd.h>
  40
  41 #include "asterisk/lock.h"
  42 #include "asterisk/logger.h"
  43 #include "asterisk/linkedlists.h"
  44 #include "asterisk/module.h"
  45 #include "asterisk/config.h"
  46 #include "asterisk/options.h"
  47 #include "asterisk/translate.h"
  48 #include "asterisk/channel.h"
  49 #include "asterisk/utils.h"
  50
  51 /* define NOT_BLI to use a faster but not bit-level identical version */
  52 /* #define NOT_BLI */
  53
  54 #define BUFFER_SAMPLES   8096   /* size for the translation buffers */
  55
  56 /* Sample frame data */
  57
  58 #include "slin_adpcm_ex.h"
  59 #include "adpcm_slin_ex.h"
  60
  61 /*
  62  * Step size index shift table
  63  */
  64
  65 static int indsft[8] = { -1, -1, -1, -1, 2, 4, 6, 8 };
  66
  67 /*
  68  * Step size table, where stpsz[i]=floor[16*(11/10)^i]
  69  */
  70
  71 static int stpsz[49] = {
  72   16, 17, 19, 21, 23, 25, 28, 31, 34, 37, 41, 45, 50, 55, 60, 66, 73,
  73   80, 88, 97, 107, 118, 130, 143, 157, 173, 190, 209, 230, 253, 279,
  74   307, 337, 371, 408, 449, 494, 544, 598, 658, 724, 796, 876, 963,
  75   1060, 1166, 1282, 1411, 1552
  76 };
  77
  78 /*
  79  * Decoder/Encoder state
  80  *   States for both encoder and decoder are synchronized
  81  */
  82 struct adpcm_state {
  83         int ssindex;
  84         int signal;
  85         int zero_count;
  86         int next_flag;
  87 };
  88
  89 /*
  90  * Decode(encoded)
  91  *  Decodes the encoded nibble from the adpcm file.
  92  *
  93  * Results:
  94  *  Returns the encoded difference.
  95  *
  96  * Side effects:
  97  *  Sets the index to the step size table for the next encode.
  98  */
  99
 100 static inline short decode(int encoded, struct adpcm_state *state)
 101 {
 102         int diff;
 103         int step;
 104         int sign;
 105
 106         step = stpsz[state->ssindex];
 107
 108         sign = encoded & 0x08;
 109         encoded &= 0x07;
 110 #ifdef NOT_BLI
 111         diff = (((encoded << 1) + 1) * step) >> 3;
 112 #else /* BLI code */
 113         diff = step >> 3;
 114         if (encoded & 4)
 115                 diff += step;
 116         if (encoded & 2)
 117                 diff += step >> 1;
 118         if (encoded & 1)
 119                 diff += step >> 2;
 120         if ((encoded >> 1) & step & 0x1)
 121                 diff++;
 122 #endif
 123         if (sign)
 124                 diff = -diff;
 125
 126         if (state->next_flag & 0x1)
 127                 state->signal -= 8;
 128         else if (state->next_flag & 0x2)
 129                 state->signal += 8;
 130
 131         state->signal += diff;
 132
 133         if (state->signal > 2047)
 134                 state->signal = 2047;
 135         else if (state->signal < -2047)
 136                 state->signal = -2047;
 137
 138         state->next_flag = 0;
 139
 140 #ifdef AUTO_RETURN
 141         if (encoded)
 142                 state->zero_count = 0;
 143         else if (++(state->zero_count) == 24) {
 144                 state->zero_count = 0;
 145                 if (state->signal > 0)
 146                         state->next_flag = 0x1;
 147                 else if (state->signal < 0)
 148                         state->next_flag = 0x2;
 149         }
 150 #endif
 151
 152         state->ssindex += indsft[encoded];
 153         if (state->ssindex < 0)
 154                 state->ssindex = 0;
 155         else if (state->ssindex > 48)
 156                 state->ssindex = 48;
 157
 158         return state->signal << 4;
 159 }
 160
 161 /*
 162  * Adpcm
 163  *  Takes a signed linear signal and encodes it as ADPCM
 164  *  For more information see http://support.dialogic.com/appnotes/adpcm.pdf
 165  *
 166  * Results:
 167  *  Foo.
 168  *
 169  * Side effects:
 170  *  signal gets updated with each pass.
 171  */
 172
 173 static inline int adpcm(short csig, struct adpcm_state *state)
 174 {
 175         int diff;
 176         int step;
 177         int encoded;
 178
 179         /*
 180          * Clip csig if too large or too small
 181          */
 182         csig >>= 4;
 183
 184         step = stpsz[state->ssindex];
 185         diff = csig - state->signal;
 186
 187 #ifdef NOT_BLI
 188         if (diff < 0) {
 189                 encoded = (-diff << 2) / step;
 190                 if (encoded > 7)
 191                         encoded = 7;
 192                 encoded |= 0x08;
 193         } else {
 194                 encoded = (diff << 2) / step;
 195                 if (encoded > 7)
 196                         encoded = 7;
 197         }
 198 #else /* BLI code */
 199         if (diff < 0) {
 200                 encoded = 8;
 201                 diff = -diff;
 202         } else
 203                 encoded = 0;
 204         if (diff >= step) {
 205                 encoded |= 4;
 206                 diff -= step;
 207         }
 208         step >>= 1;
 209         if (diff >= step) {
 210                 encoded |= 2;
 211                 diff -= step;
 212         }
 213         step >>= 1;
 214         if (diff >= step)
 215                 encoded |= 1;
 216 #endif /* NOT_BLI */
 217
 218         /* feedback to state */
 219         decode(encoded, state);
 220
 221         return encoded;
 222 }
 223
 224 /*----------------- Asterisk-codec glue ------------*/
 225
 226 /*! \brief Workspace for translating signed linear signals to ADPCM. */
 227 struct adpcm_encoder_pvt {
 228         struct adpcm_state state;
 229         int16_t inbuf[BUFFER_SAMPLES];  /* Unencoded signed linear values */
 230 };
 231
 232 /*! \brief Workspace for translating ADPCM signals to signed linear. */
 233 struct adpcm_decoder_pvt {
 234         struct adpcm_state state;
 235 };
 236
 237 /*! \brief decode 4-bit adpcm frame data and store in output buffer */
 238 static int adpcmtolin_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
 239 {
 240         struct adpcm_decoder_pvt *tmp = pvt->pvt;
 241         int x = f->datalen;
 242         unsigned char *src = f->data;
 243         int16_t *dst = (int16_t *)pvt->outbuf + pvt->samples;
 244
 245         while (x--) {
 246                 *dst++ = decode((*src >> 4) & 0xf, &tmp->state);
 247                 *dst++ = decode(*src++ & 0x0f, &tmp->state);
 248         }
 249         pvt->samples += f->samples;
 250         pvt->datalen += 2*f->samples;
 251         return 0;
 252 }
 253
 254 /*! \brief fill input buffer with 16-bit signed linear PCM values. */
 255 static int lintoadpcm_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
 256 {
 257         struct adpcm_encoder_pvt *tmp = pvt->pvt;
 258
 259         memcpy(&tmp->inbuf[pvt->samples], f->data, f->datalen);
 260         pvt->samples += f->samples;
 261         return 0;
 262 }
 263
 264 /*! \brief convert inbuf and store into frame */
 265 static struct ast_frame *lintoadpcm_frameout(struct ast_trans_pvt *pvt)
 266 {
 267         struct adpcm_encoder_pvt *tmp = pvt->pvt;
 268         struct ast_frame *f;
 269         int i;
 270         int samples = pvt->samples;     /* save original number */
 271
 272         if (samples < 2)
 273                 return NULL;
 274
 275         pvt->samples &= ~1; /* atomic size is 2 samples */
 276
 277         for (i = 0; i < pvt->samples; i += 2) {
 278                 pvt->outbuf[i/2] =
 279                         (adpcm(tmp->inbuf[i  ], &tmp->state) << 4) |
 280                         (adpcm(tmp->inbuf[i+1], &tmp->state)     );
 281         };
 282
 283         f = ast_trans_frameout(pvt, pvt->samples/2, 0);
 284
 285         /*
 286          * If there is a left over sample, move it to the beginning
 287          * of the input buffer.
 288          */
 289
 290         if (samples & 1) {      /* move the leftover sample at beginning */
 291                 tmp->inbuf[0] = tmp->inbuf[samples - 1];
 292                 pvt->samples = 1;
 293         }
 294         return f;
 295 }
 296
 297
 298 /*! \brief AdpcmToLin_Sample */
 299 static struct ast_frame *adpcmtolin_sample(void)
 300 {
 301         static struct ast_frame f;
 302         f.frametype = AST_FRAME_VOICE;
 303         f.subclass = AST_FORMAT_ADPCM;
 304         f.datalen = sizeof(adpcm_slin_ex);
 305         f.samples = sizeof(adpcm_slin_ex) * 2;
 306         f.mallocd = 0;
 307         f.offset = 0;
 308         f.src = __PRETTY_FUNCTION__;
 309         f.data = adpcm_slin_ex;
 310         return &f;
 311 }
 312
 313 /*! \brief LinToAdpcm_Sample */
 314 static struct ast_frame *lintoadpcm_sample(void)
 315 {
 316         static struct ast_frame f;
 317         f.frametype = AST_FRAME_VOICE;
 318         f.subclass = AST_FORMAT_SLINEAR;
 319         f.datalen = sizeof(slin_adpcm_ex);
 320         /* Assume 8000 Hz */
 321         f.samples = sizeof(slin_adpcm_ex) / 2;
 322         f.mallocd = 0;
 323         f.offset = 0;
 324         f.src = __PRETTY_FUNCTION__;
 325         f.data = slin_adpcm_ex;
 326         return &f;
 327 }
 328
 329 static struct ast_translator adpcmtolin = {
 330         .name = "adpcmtolin",
 331         .srcfmt = AST_FORMAT_ADPCM,
 332         .dstfmt = AST_FORMAT_SLINEAR,
 333         .framein = adpcmtolin_framein,
 334         .sample = adpcmtolin_sample,
 335         .desc_size = sizeof(struct adpcm_decoder_pvt),
 336         .buffer_samples = BUFFER_SAMPLES,
 337         .buf_size = BUFFER_SAMPLES * 2,
 338         .plc_samples = 160,
 339 };
 340
 341 static struct ast_translator lintoadpcm = {
 342         .name = "lintoadpcm",
 343         .srcfmt = AST_FORMAT_SLINEAR,
 344         .dstfmt = AST_FORMAT_ADPCM,
 345         .framein = lintoadpcm_framein,
 346         .frameout = lintoadpcm_frameout,
 347         .sample = lintoadpcm_sample,
 348         .desc_size = sizeof (struct adpcm_encoder_pvt),
 349         .buffer_samples = BUFFER_SAMPLES,
 350         .buf_size = BUFFER_SAMPLES/ 2,  /* 2 samples per byte */
 351 };
 352
 353 static void parse_config(void)
 354 {
 355         struct ast_config *cfg = ast_config_load("codecs.conf");
 356         struct ast_variable *var;
 357         if (cfg == NULL)
 358                 return;
 359         for (var = ast_variable_browse(cfg, "plc"); var ; var = var->next) {
 360                 if (!strcasecmp(var->name, "genericplc")) {
 361                         adpcmtolin.useplc = ast_true(var->value) ? 1 : 0;
 362                         if (option_verbose > 2)
 363                                 ast_verbose(VERBOSE_PREFIX_3 "codec_adpcm: %susing generic PLC\n", adpcmtolin.useplc ? "" : "not ");
 364                 }
 365         }
 366         ast_config_destroy(cfg);
 367 }
 368
 369 /*! \brief standard module glue */
 370 static int reload(void)
 371 {
 372         parse_config();
 373         return 0;
 374 }
 375
 376 static int unload_module(void)
 377 {
 378         int res;
 379
 380         res = ast_unregister_translator(&lintoadpcm);
 381         res |= ast_unregister_translator(&adpcmtolin);
 382
 383         return res;
 384 }
 385
 386 static int load_module(void)
 387 {
 388         int res;
 389
 390         parse_config();
 391         res = ast_register_translator(&adpcmtolin);
 392         if (!res)
 393                 res = ast_register_translator(&lintoadpcm);
 394         else
 395                 ast_unregister_translator(&adpcmtolin);
 396
 397         return res;
 398 }
 399
 400 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "Adaptive Differential PCM Coder/Decoder",
 401                 .load = load_module,
 402                 .unload = unload_module,
 403                 .reload = reload,
 404                );