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   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 "bitstream.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
 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  * Apply generic gain control.
 416  *
 417  * @param v_out output vector
 418  * @param v_in gain-controlled vector
 419  * @param v_ref vector to control gain of
 420  *
 421  * FIXME: If v_ref is a zero vector, it energy is zero
 422  *        and the behavior of the gain control is
 423  *        undefined in the specs.
 424  *
 425  * TIA/EIA/IS-733 2.4.8.3-2/3/4/5, 2.4.8.6
 426  */
 427 static void apply_gain_ctrl(float *v_out, const float *v_ref,
 428                             const float *v_in)
 429 {
 430     int   i, j, len;
 431     float scalefactor;
 432
 433     for(i=0, j=0; i<4; i++)
 434     {
 435         scalefactor = ff_dot_productf(v_in + j, v_in + j, 40);
 436         if(scalefactor)
 437             scalefactor = sqrt(ff_dot_productf(v_ref + j, v_ref + j, 40)
 438                         / scalefactor);
 439         else
 440             ff_log_missing_feature(NULL, "Zero energy for gain control", 1);
 441         for(len=j+40; j<len; j++)
 442             v_out[j] = scalefactor * v_in[j];
 443     }
 444 }
 445
 446 /**
 447  * Apply filter in pitch-subframe steps.
 448  *
 449  * @param memory buffer for the previous state of the filter
 450  *        - must be able to contain 303 elements
 451  *        - the 143 first elements are from the previous state
 452  *        - the next 160 are for output
 453  * @param v_in input filter vector
 454  * @param gain per-subframe gain array, each element is between 0.0 and 2.0
 455  * @param lag per-subframe lag array, each element is
 456  *        - between 16 and 143 if its corresponding pfrac is 0,
 457  *        - between 16 and 139 otherwise
 458  * @param pfrac per-subframe boolean array, 1 if the lag is fractional, 0
 459  *        otherwise
 460  *
 461  * @return filter output vector
 462  */
 463 static const float *do_pitchfilter(float memory[303], const float v_in[160],
 464                                    const float gain[4], const uint8_t *lag,
 465                                    const uint8_t pfrac[4])
 466 {
 467     int         i, j;
 468     float       *v_lag, *v_out;
 469     const float *v_len;
 470
 471     v_out = memory + 143; // Output vector starts at memory[143].
 472
 473     for(i=0; i<4; i++)
 474     {
 475         if(gain[i])
 476         {
 477             v_lag = memory + 143 + 40 * i - lag[i];
 478             for(v_len=v_in+40; v_in<v_len; v_in++)
 479             {
 480                 if(pfrac[i]) // If it is a fractional lag...
 481                 {
 482                     for(j=0, *v_out=0.; j<4; j++)
 483                         *v_out += qcelp_hammsinc_table[j] * (v_lag[j-4] + v_lag[3-j]);
 484                 }else
 485                     *v_out = *v_lag;
 486
 487                 *v_out = *v_in + gain[i] * *v_out;
 488
 489                 v_lag++;
 490                 v_out++;
 491             }
 492         }else
 493         {
 494             memcpy(v_out, v_in, 40 * sizeof(float));
 495             v_in  += 40;
 496             v_out += 40;
 497         }
 498     }
 499
 500     memmove(memory, memory + 160, 143 * sizeof(float));
 501     return memory + 143;
 502 }
 503
 504 /**
 505  * Apply pitch synthesis filter and pitch prefilter to the scaled codebook vector.
 506  * TIA/EIA/IS-733 2.4.5.2, 2.4.8.7.2
 507  *
 508  * @param q the context
 509  * @param cdn_vector the scaled codebook vector
 510  */
 511 static void apply_pitch_filters(QCELPContext *q, float *cdn_vector)
 512 {
 513     int         i;
 514     const float *v_synthesis_filtered, *v_pre_filtered;
 515
 516     if(q->bitrate >= RATE_HALF ||
 517        q->bitrate == SILENCE ||
 518        (q->bitrate == I_F_Q && (q->prev_bitrate >= RATE_HALF)))
 519     {
 520
 521         if(q->bitrate >= RATE_HALF)
 522         {
 523
 524             // Compute gain & lag for the whole frame.
 525             for(i=0; i<4; i++)
 526             {
 527                 q->pitch_gain[i] = q->frame.plag[i] ? (q->frame.pgain[i] + 1) * 0.25 : 0.0;
 528
 529                 q->pitch_lag[i] = q->frame.plag[i] + 16;
 530             }
 531         }else
 532         {
 533             float max_pitch_gain;
 534
 535             if (q->bitrate == I_F_Q)
 536             {
 537                   if (q->erasure_count < 3)
 538                       max_pitch_gain = 0.9 - 0.3 * (q->erasure_count - 1);
 539                   else
 540                       max_pitch_gain = 0.0;
 541             }else
 542             {
 543                 assert(q->bitrate == SILENCE);
 544                 max_pitch_gain = 1.0;
 545             }
 546             for(i=0; i<4; i++)
 547                 q->pitch_gain[i] = FFMIN(q->pitch_gain[i], max_pitch_gain);
 548
 549             memset(q->frame.pfrac, 0, sizeof(q->frame.pfrac));
 550         }
 551
 552         // pitch synthesis filter
 553         v_synthesis_filtered = do_pitchfilter(q->pitch_synthesis_filter_mem,
 554                                               cdn_vector, q->pitch_gain,
 555                                               q->pitch_lag, q->frame.pfrac);
 556
 557         // pitch prefilter update
 558         for(i=0; i<4; i++)
 559             q->pitch_gain[i] = 0.5 * FFMIN(q->pitch_gain[i], 1.0);
 560
 561         v_pre_filtered = do_pitchfilter(q->pitch_pre_filter_mem,
 562                                         v_synthesis_filtered,
 563                                         q->pitch_gain, q->pitch_lag,
 564                                         q->frame.pfrac);
 565
 566         apply_gain_ctrl(cdn_vector, v_synthesis_filtered, v_pre_filtered);
 567     }else
 568     {
 569         memcpy(q->pitch_synthesis_filter_mem, cdn_vector + 17,
 570                143 * sizeof(float));
 571         memcpy(q->pitch_pre_filter_mem, cdn_vector + 17, 143 * sizeof(float));
 572         memset(q->pitch_gain, 0, sizeof(q->pitch_gain));
 573         memset(q->pitch_lag,  0, sizeof(q->pitch_lag));
 574     }
 575 }
 576
 577 /**
 578  * Reconstructs LPC coefficients from the line spectral pair frequencies
 579  * and performs bandwidth expansion.
 580  *
 581  * @param lspf line spectral pair frequencies
 582  * @param lpc linear predictive coding coefficients
 583  *
 584  * @note: bandwith_expansion_coeff could be precalculated into a table
 585  *        but it seems to be slower on x86
 586  *
 587  * TIA/EIA/IS-733 2.4.3.3.5
 588  */
 589 void lspf2lpc(const float *lspf, float *lpc)
 590 {
 591     double lsf[10];
 592     double bandwith_expansion_coeff = QCELP_BANDWITH_EXPANSION_COEFF;
 593     int   i;
 594
 595     for (i=0; i<10; i++)
 596         lsf[i] = cos(M_PI * lspf[i]);
 597
 598     ff_celp_lspf2lpc(lsf, lpc);
 599
 600     for (i=0; i<10; i++)
 601     {
 602         lpc[i] *= bandwith_expansion_coeff;
 603         bandwith_expansion_coeff *= QCELP_BANDWITH_EXPANSION_COEFF;
 604     }
 605 }
 606
 607 /**
 608  * Interpolates LSP frequencies and computes LPC coefficients
 609  * for a given bitrate & pitch subframe.
 610  *
 611  * TIA/EIA/IS-733 2.4.3.3.4, 2.4.8.7.2
 612  *
 613  * @param q the context
 614  * @param curr_lspf LSP frequencies vector of the current frame
 615  * @param lpc float vector for the resulting LPC
 616  * @param subframe_num frame number in decoded stream
 617  */
 618 void interpolate_lpc(QCELPContext *q, const float *curr_lspf, float *lpc,
 619                      const int subframe_num)
 620 {
 621     float interpolated_lspf[10];
 622     float weight;
 623
 624     if(q->bitrate >= RATE_QUARTER)
 625         weight = 0.25 * (subframe_num + 1);
 626     else if(q->bitrate == RATE_OCTAVE && !subframe_num)
 627         weight = 0.625;
 628     else
 629         weight = 1.0;
 630
 631     if(weight != 1.0)
 632     {
 633         ff_weighted_vector_sumf(interpolated_lspf, curr_lspf, q->prev_lspf,
 634                              weight, 1.0 - weight, 10);
 635         lspf2lpc(interpolated_lspf, lpc);
 636     }else if(q->bitrate >= RATE_QUARTER ||
 637              (q->bitrate == I_F_Q && !subframe_num))
 638         lspf2lpc(curr_lspf, lpc);
 639     else if(q->bitrate == SILENCE && !subframe_num)
 640         lspf2lpc(q->prev_lspf, lpc);
 641 }
 642
 643 static qcelp_packet_rate buf_size2bitrate(const int buf_size)
 644 {
 645     switch(buf_size)
 646     {
 647         case 35: return RATE_FULL;
 648         case 17: return RATE_HALF;
 649         case  8: return RATE_QUARTER;
 650         case  4: return RATE_OCTAVE;
 651         case  1: return SILENCE;
 652     }
 653
 654     return I_F_Q;
 655 }
 656
 657 /**
 658  * Determine the bitrate from the frame size and/or the first byte of the frame.
 659  *
 660  * @param avctx the AV codec context
 661  * @param buf_size length of the buffer
 662  * @param buf the bufffer
 663  *
 664  * @return the bitrate on success,
 665  *         I_F_Q  if the bitrate cannot be satisfactorily determined
 666  *
 667  * TIA/EIA/IS-733 2.4.8.7.1
 668  */
 669 static qcelp_packet_rate determine_bitrate(AVCodecContext *avctx, const int buf_size,
 670                              const uint8_t **buf)
 671 {
 672     qcelp_packet_rate bitrate;
 673
 674     if((bitrate = buf_size2bitrate(buf_size)) >= 0)
 675     {
 676         if(bitrate > **buf)
 677         {
 678             QCELPContext *q = avctx->priv_data;
 679             if (!q->warned_buf_mismatch_bitrate)
 680             {
 681             av_log(avctx, AV_LOG_WARNING,
 682                    "Claimed bitrate and buffer size mismatch.\n");
 683                 q->warned_buf_mismatch_bitrate = 1;
 684             }
 685             bitrate = **buf;
 686         }else if(bitrate < **buf)
 687         {
 688             av_log(avctx, AV_LOG_ERROR,
 689                    "Buffer is too small for the claimed bitrate.\n");
 690             return I_F_Q;
 691         }
 692         (*buf)++;
 693     }else if((bitrate = buf_size2bitrate(buf_size + 1)) >= 0)
 694     {
 695         av_log(avctx, AV_LOG_WARNING,
 696                "Bitrate byte is missing, guessing the bitrate from packet size.\n");
 697     }else
 698         return I_F_Q;
 699
 700     if(bitrate == SILENCE)
 701     {
 702         //FIXME: Remove experimental warning when tested with samples.
 703         ff_log_ask_for_sample(avctx, "'Blank frame handling is experimental.");
 704     }
 705     return bitrate;
 706 }
 707
 708 static void warn_insufficient_frame_quality(AVCodecContext *avctx,
 709                                             const char *message)
 710 {
 711     av_log(avctx, AV_LOG_WARNING, "Frame #%d, IFQ: %s\n", avctx->frame_number,
 712            message);
 713 }
 714
 715 static int qcelp_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
 716                               const uint8_t *buf, int buf_size)
 717 {
 718     QCELPContext *q = avctx->priv_data;
 719     float *outbuffer = data;
 720     int   i;
 721     float quantized_lspf[10], lpc[10];
 722     float gain[16];
 723     float *formant_mem;
 724
 725     if((q->bitrate = determine_bitrate(avctx, buf_size, &buf)) == I_F_Q)
 726     {
 727         warn_insufficient_frame_quality(avctx, "bitrate cannot be determined.");
 728         goto erasure;
 729     }
 730
 731     if(q->bitrate == RATE_OCTAVE &&
 732        (q->first16bits = AV_RB16(buf)) == 0xFFFF)
 733     {
 734         warn_insufficient_frame_quality(avctx, "Bitrate is 1/8 and first 16 bits are on.");
 735         goto erasure;
 736     }
 737
 738     if(q->bitrate > SILENCE)
 739     {
 740         const QCELPBitmap *bitmaps     = qcelp_unpacking_bitmaps_per_rate[q->bitrate];
 741         const QCELPBitmap *bitmaps_end = qcelp_unpacking_bitmaps_per_rate[q->bitrate]
 742                                        + qcelp_unpacking_bitmaps_lengths[q->bitrate];
 743         uint8_t           *unpacked_data = (uint8_t *)&q->frame;
 744
 745         init_get_bits(&q->gb, buf, 8*buf_size);
 746
 747         memset(&q->frame, 0, sizeof(QCELPFrame));
 748
 749         for(; bitmaps < bitmaps_end; bitmaps++)
 750             unpacked_data[bitmaps->index] |= get_bits(&q->gb, bitmaps->bitlen) << bitmaps->bitpos;
 751
 752         // Check for erasures/blanks on rates 1, 1/4 and 1/8.
 753         if(q->frame.reserved)
 754         {
 755             warn_insufficient_frame_quality(avctx, "Wrong data in reserved frame area.");
 756             goto erasure;
 757         }
 758         if(q->bitrate == RATE_QUARTER &&
 759            codebook_sanity_check_for_rate_quarter(q->frame.cbgain))
 760         {
 761             warn_insufficient_frame_quality(avctx, "Codebook gain sanity check failed.");
 762             goto erasure;
 763         }
 764
 765         if(q->bitrate >= RATE_HALF)
 766         {
 767             for(i=0; i<4; i++)
 768             {
 769                 if(q->frame.pfrac[i] && q->frame.plag[i] >= 124)
 770                 {
 771                     warn_insufficient_frame_quality(avctx, "Cannot initialize pitch filter.");
 772                     goto erasure;
 773                 }
 774             }
 775         }
 776     }
 777
 778     decode_gain_and_index(q, gain);
 779     compute_svector(q, gain, outbuffer);
 780
 781     if(decode_lspf(q, quantized_lspf) < 0)
 782     {
 783         warn_insufficient_frame_quality(avctx, "Badly received packets in frame.");
 784         goto erasure;
 785     }
 786
 787
 788     apply_pitch_filters(q, outbuffer);
 789
 790     if(q->bitrate == I_F_Q)
 791     {
 792 erasure:
 793         q->bitrate = I_F_Q;
 794         q->erasure_count++;
 795         decode_gain_and_index(q, gain);
 796         compute_svector(q, gain, outbuffer);
 797         decode_lspf(q, quantized_lspf);
 798         apply_pitch_filters(q, outbuffer);
 799     }else
 800         q->erasure_count = 0;
 801
 802     formant_mem = q->formant_mem + 10;
 803     for(i=0; i<4; i++)
 804     {
 805         interpolate_lpc(q, quantized_lspf, lpc, i);
 806         ff_celp_lp_synthesis_filterf(formant_mem, lpc, outbuffer + i * 40, 40,
 807                                      10);
 808         formant_mem += 40;
 809     }
 810     memcpy(q->formant_mem, q->formant_mem + 160, 10 * sizeof(float));
 811
 812     // FIXME: postfilter and final gain control should be here.
 813     // TIA/EIA/IS-733 2.4.8.6
 814
 815     formant_mem = q->formant_mem + 10;
 816     for(i=0; i<160; i++)
 817         *outbuffer++ = av_clipf(*formant_mem++, QCELP_CLIP_LOWER_BOUND,
 818                                 QCELP_CLIP_UPPER_BOUND);
 819
 820     memcpy(q->prev_lspf, quantized_lspf, sizeof(q->prev_lspf));
 821     q->prev_bitrate = q->bitrate;
 822
 823     *data_size = 160 * sizeof(*outbuffer);
 824
 825     return *data_size;
 826 }
 827
 828 AVCodec qcelp_decoder =
 829 {
 830     .name   = "qcelp",
 831     .type   = CODEC_TYPE_AUDIO,
 832     .id     = CODEC_ID_QCELP,
 833     .init   = qcelp_decode_init,
 834     .decode = qcelp_decode_frame,
 835     .priv_data_size = sizeof(QCELPContext),
 836     .long_name = NULL_IF_CONFIG_SMALL("QCELP / PureVoice"),
 837 };