libavcodec/qcelpdec.c

   1 /*
   2  * QCELP decoder
   3  * Copyright (c) 2007 Reynaldo H. Verdejo Pinochet
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file libavcodec/qcelpdec.c
  24  * QCELP decoder
  25  * @author Reynaldo H. Verdejo Pinochet
  26  * @remark FFmpeg merging spearheaded by Kenan Gillet
  27  * @remark Development mentored by Benjamin Larson
  28  */
  29
  30 #include <stddef.h>
  31
  32 #include "avcodec.h"
  33 #include "internal.h"
  34 #include "get_bits.h"
  35
  36 #include "qcelpdata.h"
  37
  38 #include "celp_math.h"
  39 #include "celp_filters.h"
  40 #include "acelp_vectors.h"
  41
  42 #undef NDEBUG
  43 #include <assert.h>
  44
  45 typedef enum
  46 {
  47     I_F_Q = -1,    /*!< insufficient frame quality */
  48     SILENCE,
  49     RATE_OCTAVE,
  50     RATE_QUARTER,
  51     RATE_HALF,
  52     RATE_FULL
  53 } qcelp_packet_rate;
  54
  55 typedef struct
  56 {
  57     GetBitContext     gb;
  58     qcelp_packet_rate bitrate;
  59     QCELPFrame        frame;    /*!< unpacked data frame */
  60
  61     uint8_t  erasure_count;
  62     uint8_t  octave_count;      /*!< count the consecutive RATE_OCTAVE frames */
  63     float    prev_lspf[10];
  64     float    predictor_lspf[10];/*!< LSP predictor for RATE_OCTAVE and I_F_Q */
  65     float    pitch_synthesis_filter_mem[303];
  66     float    pitch_pre_filter_mem[303];
  67     float    rnd_fir_filter_mem[180];
  68     float    formant_mem[170];
  69     float    last_codebook_gain;
  70     int      prev_g1[2];
  71     int      prev_bitrate;
  72     float    pitch_gain[4];
  73     uint8_t  pitch_lag[4];
  74     uint16_t first16bits;
  75     uint8_t  warned_buf_mismatch_bitrate;
  76 } QCELPContext;
  77
  78 /**
  79  * Reconstructs LPC coefficients from the line spectral pair frequencies.
  80  *
  81  * TIA/EIA/IS-733 2.4.3.3.5
  82  */
  83 void ff_celp_lspf2lpc(const double *lspf, float *lpc);
  84
  85 /**
  86  * Initialize the speech codec according to the specification.
  87  *
  88  * TIA/EIA/IS-733 2.4.9
  89  */
  90 static av_cold int qcelp_decode_init(AVCodecContext *avctx)
  91 {
  92     QCELPContext *q = avctx->priv_data;
  93     int i;
  94
  95     avctx->sample_fmt = SAMPLE_FMT_FLT;
  96
  97     for(i=0; i<10; i++)
  98         q->prev_lspf[i] = (i+1)/11.;
  99
 100     return 0;
 101 }
 102
 103 /**
 104  * Decodes the 10 quantized LSP frequencies from the LSPV/LSP
 105  * transmission codes of any bitrate and checks for badly received packets.
 106  *
 107  * @param q the context
 108  * @param lspf line spectral pair frequencies
 109  *
 110  * @return 0 on success, -1 if the packet is badly received
 111  *
 112  * TIA/EIA/IS-733 2.4.3.2.6.2-2, 2.4.8.7.3
 113  */
 114 static int decode_lspf(QCELPContext *q, float *lspf)
 115 {
 116     int i;
 117     float tmp_lspf, smooth, erasure_coeff;
 118     const float *predictors;
 119
 120     if(q->bitrate == RATE_OCTAVE || q->bitrate == I_F_Q)
 121     {
 122         predictors = (q->prev_bitrate != RATE_OCTAVE &&
 123                        q->prev_bitrate != I_F_Q ?
 124                        q->prev_lspf : q->predictor_lspf);
 125
 126         if(q->bitrate == RATE_OCTAVE)
 127         {
 128             q->octave_count++;
 129
 130             for(i=0; i<10; i++)
 131             {
 132                 q->predictor_lspf[i] =
 133                              lspf[i] = (q->frame.lspv[i] ?  QCELP_LSP_SPREAD_FACTOR
 134                                                          : -QCELP_LSP_SPREAD_FACTOR)
 135                                      + predictors[i] * QCELP_LSP_OCTAVE_PREDICTOR
 136                                      + (i + 1) * ((1 - QCELP_LSP_OCTAVE_PREDICTOR)/11);
 137             }
 138             smooth = (q->octave_count < 10 ? .875 : 0.1);
 139         }else
 140         {
 141             erasure_coeff = QCELP_LSP_OCTAVE_PREDICTOR;
 142
 143             assert(q->bitrate == I_F_Q);
 144
 145             if(q->erasure_count > 1)
 146                 erasure_coeff *= (q->erasure_count < 4 ? 0.9 : 0.7);
 147
 148             for(i=0; i<10; i++)
 149             {
 150                 q->predictor_lspf[i] =
 151                              lspf[i] = (i + 1) * ( 1 - erasure_coeff)/11
 152                                      + erasure_coeff * predictors[i];
 153             }
 154             smooth = 0.125;
 155         }
 156
 157         // Check the stability of the LSP frequencies.
 158         lspf[0] = FFMAX(lspf[0], QCELP_LSP_SPREAD_FACTOR);
 159         for(i=1; i<10; i++)
 160             lspf[i] = FFMAX(lspf[i], (lspf[i-1] + QCELP_LSP_SPREAD_FACTOR));
 161
 162         lspf[9] = FFMIN(lspf[9], (1.0 - QCELP_LSP_SPREAD_FACTOR));
 163         for(i=9; i>0; i--)
 164             lspf[i-1] = FFMIN(lspf[i-1], (lspf[i] - QCELP_LSP_SPREAD_FACTOR));
 165
 166         // Low-pass filter the LSP frequencies.
 167         ff_weighted_vector_sumf(lspf, lspf, q->prev_lspf, smooth, 1.0-smooth, 10);
 168     }else
 169     {
 170         q->octave_count = 0;
 171
 172         tmp_lspf = 0.;
 173         for(i=0; i<5 ; i++)
 174         {
 175             lspf[2*i+0] = tmp_lspf += qcelp_lspvq[i][q->frame.lspv[i]][0] * 0.0001;
 176             lspf[2*i+1] = tmp_lspf += qcelp_lspvq[i][q->frame.lspv[i]][1] * 0.0001;
 177         }
 178
 179         // Check for badly received packets.
 180         if(q->bitrate == RATE_QUARTER)
 181         {
 182             if(lspf[9] <= .70 || lspf[9] >=  .97)
 183                 return -1;
 184             for(i=3; i<10; i++)
 185                 if(fabs(lspf[i] - lspf[i-2]) < .08)
 186                     return -1;
 187         }else
 188         {
 189             if(lspf[9] <= .66 || lspf[9] >= .985)
 190                 return -1;
 191             for(i=4; i<10; i++)
 192                 if (fabs(lspf[i] - lspf[i-4]) < .0931)
 193                     return -1;
 194         }
 195     }
 196     return 0;
 197 }
 198
 199 /**
 200  * Converts codebook transmission codes to GAIN and INDEX.
 201  *
 202  * @param q the context
 203  * @param gain array holding the decoded gain
 204  *
 205  * TIA/EIA/IS-733 2.4.6.2
 206  */
 207 static void decode_gain_and_index(QCELPContext  *q,
 208                                   float *gain) {
 209     int   i, subframes_count, g1[16];
 210     float slope;
 211
 212     if(q->bitrate >= RATE_QUARTER)
 213     {
 214         switch(q->bitrate)
 215         {
 216             case RATE_FULL: subframes_count = 16; break;
 217             case RATE_HALF: subframes_count = 4;  break;
 218             default:        subframes_count = 5;
 219         }
 220         for(i=0; i<subframes_count; i++)
 221         {
 222             g1[i] = 4 * q->frame.cbgain[i];
 223             if(q->bitrate == RATE_FULL && !((i+1) & 3))
 224             {
 225                 g1[i] += av_clip((g1[i-1] + g1[i-2] + g1[i-3]) / 3 - 6, 0, 32);
 226             }
 227
 228             gain[i] = qcelp_g12ga[g1[i]];
 229
 230             if(q->frame.cbsign[i])
 231             {
 232                 gain[i] = -gain[i];
 233                 q->frame.cindex[i] = (q->frame.cindex[i]-89) & 127;
 234             }
 235         }
 236
 237         q->prev_g1[0] = g1[i-2];
 238         q->prev_g1[1] = g1[i-1];
 239         q->last_codebook_gain = qcelp_g12ga[g1[i-1]];
 240
 241         if(q->bitrate == RATE_QUARTER)
 242         {
 243             // Provide smoothing of the unvoiced excitation energy.
 244             gain[7] =     gain[4];
 245             gain[6] = 0.4*gain[3] + 0.6*gain[4];
 246             gain[5] =     gain[3];
 247             gain[4] = 0.8*gain[2] + 0.2*gain[3];
 248             gain[3] = 0.2*gain[1] + 0.8*gain[2];
 249             gain[2] =     gain[1];
 250             gain[1] = 0.6*gain[0] + 0.4*gain[1];
 251         }
 252     }else if (q->bitrate != SILENCE)
 253     {
 254         if(q->bitrate == RATE_OCTAVE)
 255         {
 256             g1[0] = 2 * q->frame.cbgain[0]
 257                   + av_clip((q->prev_g1[0] + q->prev_g1[1]) / 2 - 5, 0, 54);
 258             subframes_count = 8;
 259         }else
 260         {
 261             assert(q->bitrate == I_F_Q);
 262
 263             g1[0] = q->prev_g1[1];
 264             switch(q->erasure_count)
 265             {
 266                 case 1 : break;
 267                 case 2 : g1[0] -= 1; break;
 268                 case 3 : g1[0] -= 2; break;
 269                 default: g1[0] -= 6;
 270             }
 271             if(g1[0] < 0)
 272                 g1[0] = 0;
 273             subframes_count = 4;
 274         }
 275         // This interpolation is done to produce smoother background noise.
 276         slope = 0.5*(qcelp_g12ga[g1[0]] - q->last_codebook_gain) / subframes_count;
 277         for(i=1; i<=subframes_count; i++)
 278             gain[i-1] = q->last_codebook_gain + slope * i;
 279
 280         q->last_codebook_gain = gain[i-2];
 281         q->prev_g1[0] = q->prev_g1[1];
 282         q->prev_g1[1] = g1[0];
 283     }
 284 }
 285
 286 /**
 287  * If the received packet is Rate 1/4 a further sanity check is made of the
 288  * codebook gain.
 289  *
 290  * @param cbgain the unpacked cbgain array
 291  * @return -1 if the sanity check fails, 0 otherwise
 292  *
 293  * TIA/EIA/IS-733 2.4.8.7.3
 294  */
 295 static int codebook_sanity_check_for_rate_quarter(const uint8_t *cbgain)
 296 {
 297     int i, diff, prev_diff=0;
 298
 299     for(i=1; i<5; i++)
 300     {
 301         diff = cbgain[i] - cbgain[i-1];
 302         if(FFABS(diff) > 10)
 303             return -1;
 304         else if(FFABS(diff - prev_diff) > 12)
 305             return -1;
 306         prev_diff = diff;
 307     }
 308     return 0;
 309 }
 310
 311 /**
 312  * Computes the scaled codebook vector Cdn From INDEX and GAIN
 313  * for all rates.
 314  *
 315  * The specification lacks some information here.
 316  *
 317  * TIA/EIA/IS-733 has an omission on the codebook index determination
 318  * formula for RATE_FULL and RATE_HALF frames at section 2.4.8.1.1. It says
 319  * you have to subtract the decoded index parameter from the given scaled
 320  * codebook vector index 'n' to get the desired circular codebook index, but
 321  * it does not mention that you have to clamp 'n' to [0-9] in order to get
 322  * RI-compliant results.
 323  *
 324  * The reason for this mistake seems to be the fact they forgot to mention you
 325  * have to do these calculations per codebook subframe and adjust given
 326  * equation values accordingly.
 327  *
 328  * @param q the context
 329  * @param gain array holding the 4 pitch subframe gain values
 330  * @param cdn_vector array for the generated scaled codebook vector
 331  */
 332 static void compute_svector(QCELPContext *q, const float *gain,
 333                             float *cdn_vector)
 334 {
 335     int      i, j, k;
 336     uint16_t cbseed, cindex;
 337     float    *rnd, tmp_gain, fir_filter_value;
 338
 339     switch(q->bitrate)
 340     {
 341         case RATE_FULL:
 342             for(i=0; i<16; i++)
 343             {
 344                 tmp_gain = gain[i] * QCELP_RATE_FULL_CODEBOOK_RATIO;
 345                 cindex = -q->frame.cindex[i];
 346                 for(j=0; j<10; j++)
 347                     *cdn_vector++ = tmp_gain * qcelp_rate_full_codebook[cindex++ & 127];
 348             }
 349         break;
 350         case RATE_HALF:
 351             for(i=0; i<4; i++)
 352             {
 353                 tmp_gain = gain[i] * QCELP_RATE_HALF_CODEBOOK_RATIO;
 354                 cindex = -q->frame.cindex[i];
 355                 for (j = 0; j < 40; j++)
 356                 *cdn_vector++ = tmp_gain * qcelp_rate_half_codebook[cindex++ & 127];
 357             }
 358         break;
 359         case RATE_QUARTER:
 360             cbseed = (0x0003 & q->frame.lspv[4])<<14 |
 361                      (0x003F & q->frame.lspv[3])<< 8 |
 362                      (0x0060 & q->frame.lspv[2])<< 1 |
 363                      (0x0007 & q->frame.lspv[1])<< 3 |
 364                      (0x0038 & q->frame.lspv[0])>> 3 ;
 365             rnd = q->rnd_fir_filter_mem + 20;
 366             for(i=0; i<8; i++)
 367             {
 368                 tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
 369                 for(k=0; k<20; k++)
 370                 {
 371                     cbseed = 521 * cbseed + 259;
 372                     *rnd = (int16_t)cbseed;
 373
 374                     // FIR filter
 375                     fir_filter_value = 0.0;
 376                     for(j=0; j<10; j++)
 377                         fir_filter_value += qcelp_rnd_fir_coefs[j ]
 378                                           * (rnd[-j ] + rnd[-20+j]);
 379
 380                     fir_filter_value += qcelp_rnd_fir_coefs[10] * rnd[-10];
 381                     *cdn_vector++ = tmp_gain * fir_filter_value;
 382                     rnd++;
 383                 }
 384             }
 385             memcpy(q->rnd_fir_filter_mem, q->rnd_fir_filter_mem + 160, 20 * sizeof(float));
 386         break;
 387         case RATE_OCTAVE:
 388             cbseed = q->first16bits;
 389             for(i=0; i<8; i++)
 390             {
 391                 tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
 392                 for(j=0; j<20; j++)
 393                 {
 394                     cbseed = 521 * cbseed + 259;
 395                     *cdn_vector++ = tmp_gain * (int16_t)cbseed;
 396                 }
 397             }
 398         break;
 399         case I_F_Q:
 400             cbseed = -44; // random codebook index
 401             for(i=0; i<4; i++)
 402             {
 403                 tmp_gain = gain[i] * QCELP_RATE_FULL_CODEBOOK_RATIO;
 404                 for(j=0; j<40; j++)
 405                     *cdn_vector++ = tmp_gain * qcelp_rate_full_codebook[cbseed++ & 127];
 406             }
 407         break;
 408         case SILENCE:
 409             memset(cdn_vector, 0, 160 * sizeof(float));
 410         break;
 411     }
 412 }
 413
 414 /**
 415  * Compute the gain control
 416  *
 417  * @param v_in gain-controlled vector
 418  * @param v_ref vector to control gain of
 419  *
 420  * @return gain control
 421  *
 422  * FIXME: If v_ref is a zero vector, it energy is zero
 423  *        and the behavior of the gain control is
 424  *        undefined in the specs.
 425  *
 426  * TIA/EIA/IS-733 2.4.8.3-2/3/4/5, 2.4.8.6
 427  */
 428 static float compute_gain_ctrl(const float *v_ref, const float *v_in, const int len)
 429 {
 430     float scalefactor = ff_dot_productf(v_in, v_in, len);
 431
 432     if(scalefactor)
 433         scalefactor = sqrt(ff_dot_productf(v_ref, v_ref, len) / scalefactor);
 434     else
 435         ff_log_missing_feature(NULL, "Zero energy for gain control", 1);
 436     return scalefactor;
 437 }
 438
 439 /**
 440  * Apply generic gain control.
 441  *
 442  * @param v_out output vector
 443  * @param v_in gain-controlled vector
 444  * @param v_ref vector to control gain of
 445  *
 446  * TIA/EIA/IS-733 2.4.8.3, 2.4.8.6
 447  */
 448 static void apply_gain_ctrl(float *v_out, const float *v_ref,
 449                             const float *v_in)
 450 {
 451     int   i, j, len;
 452     float scalefactor;
 453
 454     for(i=0, j=0; i<4; i++)
 455     {
 456         scalefactor = compute_gain_ctrl(v_ref + j, v_in + j, 40);
 457         for(len=j+40; j<len; j++)
 458             v_out[j] = scalefactor * v_in[j];
 459     }
 460 }
 461
 462 /**
 463  * Apply filter in pitch-subframe steps.
 464  *
 465  * @param memory buffer for the previous state of the filter
 466  *        - must be able to contain 303 elements
 467  *        - the 143 first elements are from the previous state
 468  *        - the next 160 are for output
 469  * @param v_in input filter vector
 470  * @param gain per-subframe gain array, each element is between 0.0 and 2.0
 471  * @param lag per-subframe lag array, each element is
 472  *        - between 16 and 143 if its corresponding pfrac is 0,
 473  *        - between 16 and 139 otherwise
 474  * @param pfrac per-subframe boolean array, 1 if the lag is fractional, 0
 475  *        otherwise
 476  *
 477  * @return filter output vector
 478  */
 479 static const float *do_pitchfilter(float memory[303], const float v_in[160],
 480                                    const float gain[4], const uint8_t *lag,
 481                                    const uint8_t pfrac[4])
 482 {
 483     int         i, j;
 484     float       *v_lag, *v_out;
 485     const float *v_len;
 486
 487     v_out = memory + 143; // Output vector starts at memory[143].
 488
 489     for(i=0; i<4; i++)
 490     {
 491         if(gain[i])
 492         {
 493             v_lag = memory + 143 + 40 * i - lag[i];
 494             for(v_len=v_in+40; v_in<v_len; v_in++)
 495             {
 496                 if(pfrac[i]) // If it is a fractional lag...
 497                 {
 498                     for(j=0, *v_out=0.; j<4; j++)
 499                         *v_out += qcelp_hammsinc_table[j] * (v_lag[j-4] + v_lag[3-j]);
 500                 }else
 501                     *v_out = *v_lag;
 502
 503                 *v_out = *v_in + gain[i] * *v_out;
 504
 505                 v_lag++;
 506                 v_out++;
 507             }
 508         }else
 509         {
 510             memcpy(v_out, v_in, 40 * sizeof(float));
 511             v_in  += 40;
 512             v_out += 40;
 513         }
 514     }
 515
 516     memmove(memory, memory + 160, 143 * sizeof(float));
 517     return memory + 143;
 518 }
 519
 520 /**
 521  * Apply pitch synthesis filter and pitch prefilter to the scaled codebook vector.
 522  * TIA/EIA/IS-733 2.4.5.2, 2.4.8.7.2
 523  *
 524  * @param q the context
 525  * @param cdn_vector the scaled codebook vector
 526  */
 527 static void apply_pitch_filters(QCELPContext *q, float *cdn_vector)
 528 {
 529     int         i;
 530     const float *v_synthesis_filtered, *v_pre_filtered;
 531
 532     if(q->bitrate >= RATE_HALF ||
 533        q->bitrate == SILENCE ||
 534        (q->bitrate == I_F_Q && (q->prev_bitrate >= RATE_HALF)))
 535     {
 536
 537         if(q->bitrate >= RATE_HALF)
 538         {
 539
 540             // Compute gain & lag for the whole frame.
 541             for(i=0; i<4; i++)
 542             {
 543                 q->pitch_gain[i] = q->frame.plag[i] ? (q->frame.pgain[i] + 1) * 0.25 : 0.0;
 544
 545                 q->pitch_lag[i] = q->frame.plag[i] + 16;
 546             }
 547         }else
 548         {
 549             float max_pitch_gain;
 550
 551             if (q->bitrate == I_F_Q)
 552             {
 553                   if (q->erasure_count < 3)
 554                       max_pitch_gain = 0.9 - 0.3 * (q->erasure_count - 1);
 555                   else
 556                       max_pitch_gain = 0.0;
 557             }else
 558             {
 559                 assert(q->bitrate == SILENCE);
 560                 max_pitch_gain = 1.0;
 561             }
 562             for(i=0; i<4; i++)
 563                 q->pitch_gain[i] = FFMIN(q->pitch_gain[i], max_pitch_gain);
 564
 565             memset(q->frame.pfrac, 0, sizeof(q->frame.pfrac));
 566         }
 567
 568         // pitch synthesis filter
 569         v_synthesis_filtered = do_pitchfilter(q->pitch_synthesis_filter_mem,
 570                                               cdn_vector, q->pitch_gain,
 571                                               q->pitch_lag, q->frame.pfrac);
 572
 573         // pitch prefilter update
 574         for(i=0; i<4; i++)
 575             q->pitch_gain[i] = 0.5 * FFMIN(q->pitch_gain[i], 1.0);
 576
 577         v_pre_filtered = do_pitchfilter(q->pitch_pre_filter_mem,
 578                                         v_synthesis_filtered,
 579                                         q->pitch_gain, q->pitch_lag,
 580                                         q->frame.pfrac);
 581
 582         apply_gain_ctrl(cdn_vector, v_synthesis_filtered, v_pre_filtered);
 583     }else
 584     {
 585         memcpy(q->pitch_synthesis_filter_mem, cdn_vector + 17,
 586                143 * sizeof(float));
 587         memcpy(q->pitch_pre_filter_mem, cdn_vector + 17, 143 * sizeof(float));
 588         memset(q->pitch_gain, 0, sizeof(q->pitch_gain));
 589         memset(q->pitch_lag,  0, sizeof(q->pitch_lag));
 590     }
 591 }
 592
 593 /**
 594  * Reconstructs LPC coefficients from the line spectral pair frequencies
 595  * and performs bandwidth expansion.
 596  *
 597  * @param lspf line spectral pair frequencies
 598  * @param lpc linear predictive coding coefficients
 599  *
 600  * @note: bandwith_expansion_coeff could be precalculated into a table
 601  *        but it seems to be slower on x86
 602  *
 603  * TIA/EIA/IS-733 2.4.3.3.5
 604  */
 605 static void lspf2lpc(const float *lspf, float *lpc)
 606 {
 607     double lsf[10];
 608     double bandwith_expansion_coeff = QCELP_BANDWITH_EXPANSION_COEFF;
 609     int   i;
 610
 611     for (i=0; i<10; i++)
 612         lsf[i] = cos(M_PI * lspf[i]);
 613
 614     ff_celp_lspf2lpc(lsf, lpc);
 615
 616     for (i=0; i<10; i++)
 617     {
 618         lpc[i] *= bandwith_expansion_coeff;
 619         bandwith_expansion_coeff *= QCELP_BANDWITH_EXPANSION_COEFF;
 620     }
 621 }
 622
 623 /**
 624  * Interpolates LSP frequencies and computes LPC coefficients
 625  * for a given bitrate & pitch subframe.
 626  *
 627  * TIA/EIA/IS-733 2.4.3.3.4, 2.4.8.7.2
 628  *
 629  * @param q the context
 630  * @param curr_lspf LSP frequencies vector of the current frame
 631  * @param lpc float vector for the resulting LPC
 632  * @param subframe_num frame number in decoded stream
 633  */
 634 void interpolate_lpc(QCELPContext *q, const float *curr_lspf, float *lpc,
 635                      const int subframe_num)
 636 {
 637     float interpolated_lspf[10];
 638     float weight;
 639
 640     if(q->bitrate >= RATE_QUARTER)
 641         weight = 0.25 * (subframe_num + 1);
 642     else if(q->bitrate == RATE_OCTAVE && !subframe_num)
 643         weight = 0.625;
 644     else
 645         weight = 1.0;
 646
 647     if(weight != 1.0)
 648     {
 649         ff_weighted_vector_sumf(interpolated_lspf, curr_lspf, q->prev_lspf,
 650                                 weight, 1.0 - weight, 10);
 651         lspf2lpc(interpolated_lspf, lpc);
 652     }else if(q->bitrate >= RATE_QUARTER ||
 653              (q->bitrate == I_F_Q && !subframe_num))
 654         lspf2lpc(curr_lspf, lpc);
 655     else if(q->bitrate == SILENCE && !subframe_num)
 656         lspf2lpc(q->prev_lspf, lpc);
 657 }
 658
 659 static qcelp_packet_rate buf_size2bitrate(const int buf_size)
 660 {
 661     switch(buf_size)
 662     {
 663         case 35: return RATE_FULL;
 664         case 17: return RATE_HALF;
 665         case  8: return RATE_QUARTER;
 666         case  4: return RATE_OCTAVE;
 667         case  1: return SILENCE;
 668     }
 669
 670     return I_F_Q;
 671 }
 672
 673 /**
 674  * Determine the bitrate from the frame size and/or the first byte of the frame.
 675  *
 676  * @param avctx the AV codec context
 677  * @param buf_size length of the buffer
 678  * @param buf the bufffer
 679  *
 680  * @return the bitrate on success,
 681  *         I_F_Q  if the bitrate cannot be satisfactorily determined
 682  *
 683  * TIA/EIA/IS-733 2.4.8.7.1
 684  */
 685 static qcelp_packet_rate determine_bitrate(AVCodecContext *avctx, const int buf_size,
 686                              const uint8_t **buf)
 687 {
 688     qcelp_packet_rate bitrate;
 689
 690     if((bitrate = buf_size2bitrate(buf_size)) >= 0)
 691     {
 692         if(bitrate > **buf)
 693         {
 694             QCELPContext *q = avctx->priv_data;
 695             if (!q->warned_buf_mismatch_bitrate)
 696             {
 697             av_log(avctx, AV_LOG_WARNING,
 698                    "Claimed bitrate and buffer size mismatch.\n");
 699                 q->warned_buf_mismatch_bitrate = 1;
 700             }
 701             bitrate = **buf;
 702         }else if(bitrate < **buf)
 703         {
 704             av_log(avctx, AV_LOG_ERROR,
 705                    "Buffer is too small for the claimed bitrate.\n");
 706             return I_F_Q;
 707         }
 708         (*buf)++;
 709     }else if((bitrate = buf_size2bitrate(buf_size + 1)) >= 0)
 710     {
 711         av_log(avctx, AV_LOG_WARNING,
 712                "Bitrate byte is missing, guessing the bitrate from packet size.\n");
 713     }else
 714         return I_F_Q;
 715
 716     if(bitrate == SILENCE)
 717     {
 718         //FIXME: Remove experimental warning when tested with samples.
 719         ff_log_ask_for_sample(avctx, "'Blank frame handling is experimental.");
 720     }
 721     return bitrate;
 722 }
 723
 724 static void warn_insufficient_frame_quality(AVCodecContext *avctx,
 725                                             const char *message)
 726 {
 727     av_log(avctx, AV_LOG_WARNING, "Frame #%d, IFQ: %s\n", avctx->frame_number,
 728            message);
 729 }
 730
 731 static int qcelp_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
 732                               AVPacket *avpkt)
 733 {
 734     const uint8_t *buf = avpkt->data;
 735     int buf_size = avpkt->size;
 736     QCELPContext *q = avctx->priv_data;
 737     float *outbuffer = data;
 738     int   i;
 739     float quantized_lspf[10], lpc[10];
 740     float gain[16];
 741     float *formant_mem;
 742
 743     if((q->bitrate = determine_bitrate(avctx, buf_size, &buf)) == I_F_Q)
 744     {
 745         warn_insufficient_frame_quality(avctx, "bitrate cannot be determined.");
 746         goto erasure;
 747     }
 748
 749     if(q->bitrate == RATE_OCTAVE &&
 750        (q->first16bits = AV_RB16(buf)) == 0xFFFF)
 751     {
 752         warn_insufficient_frame_quality(avctx, "Bitrate is 1/8 and first 16 bits are on.");
 753         goto erasure;
 754     }
 755
 756     if(q->bitrate > SILENCE)
 757     {
 758         const QCELPBitmap *bitmaps     = qcelp_unpacking_bitmaps_per_rate[q->bitrate];
 759         const QCELPBitmap *bitmaps_end = qcelp_unpacking_bitmaps_per_rate[q->bitrate]
 760                                        + qcelp_unpacking_bitmaps_lengths[q->bitrate];
 761         uint8_t           *unpacked_data = (uint8_t *)&q->frame;
 762
 763         init_get_bits(&q->gb, buf, 8*buf_size);
 764
 765         memset(&q->frame, 0, sizeof(QCELPFrame));
 766
 767         for(; bitmaps < bitmaps_end; bitmaps++)
 768             unpacked_data[bitmaps->index] |= get_bits(&q->gb, bitmaps->bitlen) << bitmaps->bitpos;
 769
 770         // Check for erasures/blanks on rates 1, 1/4 and 1/8.
 771         if(q->frame.reserved)
 772         {
 773             warn_insufficient_frame_quality(avctx, "Wrong data in reserved frame area.");
 774             goto erasure;
 775         }
 776         if(q->bitrate == RATE_QUARTER &&
 777            codebook_sanity_check_for_rate_quarter(q->frame.cbgain))
 778         {
 779             warn_insufficient_frame_quality(avctx, "Codebook gain sanity check failed.");
 780             goto erasure;
 781         }
 782
 783         if(q->bitrate >= RATE_HALF)
 784         {
 785             for(i=0; i<4; i++)
 786             {
 787                 if(q->frame.pfrac[i] && q->frame.plag[i] >= 124)
 788                 {
 789                     warn_insufficient_frame_quality(avctx, "Cannot initialize pitch filter.");
 790                     goto erasure;
 791                 }
 792             }
 793         }
 794     }
 795
 796     decode_gain_and_index(q, gain);
 797     compute_svector(q, gain, outbuffer);
 798
 799     if(decode_lspf(q, quantized_lspf) < 0)
 800     {
 801         warn_insufficient_frame_quality(avctx, "Badly received packets in frame.");
 802         goto erasure;
 803     }
 804
 805
 806     apply_pitch_filters(q, outbuffer);
 807
 808     if(q->bitrate == I_F_Q)
 809     {
 810 erasure:
 811         q->bitrate = I_F_Q;
 812         q->erasure_count++;
 813         decode_gain_and_index(q, gain);
 814         compute_svector(q, gain, outbuffer);
 815         decode_lspf(q, quantized_lspf);
 816         apply_pitch_filters(q, outbuffer);
 817     }else
 818         q->erasure_count = 0;
 819
 820     formant_mem = q->formant_mem + 10;
 821     for(i=0; i<4; i++)
 822     {
 823         interpolate_lpc(q, quantized_lspf, lpc, i);
 824         ff_celp_lp_synthesis_filterf(formant_mem, lpc, outbuffer + i * 40, 40,
 825                                      10);
 826         formant_mem += 40;
 827     }
 828     memcpy(q->formant_mem, q->formant_mem + 160, 10 * sizeof(float));
 829
 830     // FIXME: postfilter and final gain control should be here.
 831     // TIA/EIA/IS-733 2.4.8.6
 832
 833     formant_mem = q->formant_mem + 10;
 834     for(i=0; i<160; i++)
 835         *outbuffer++ = av_clipf(*formant_mem++, QCELP_CLIP_LOWER_BOUND,
 836                                 QCELP_CLIP_UPPER_BOUND);
 837
 838     memcpy(q->prev_lspf, quantized_lspf, sizeof(q->prev_lspf));
 839     q->prev_bitrate = q->bitrate;
 840
 841     *data_size = 160 * sizeof(*outbuffer);
 842
 843     return *data_size;
 844 }
 845
 846 AVCodec qcelp_decoder =
 847 {
 848     .name   = "qcelp",
 849     .type   = CODEC_TYPE_AUDIO,
 850     .id     = CODEC_ID_QCELP,
 851     .init   = qcelp_decode_init,
 852     .decode = qcelp_decode_frame,
 853     .priv_data_size = sizeof(QCELPContext),
 854     .long_name = NULL_IF_CONFIG_SMALL("QCELP / PureVoice"),
 855 };