libavcodec/qcelpdec.c

   1 /*
   2  * QCELP decoder
   3  * Copyright (c) 2007 Reynaldo H. Verdejo Pinochet
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; 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
  24  * QCELP decoder
  25  * @author Reynaldo H. Verdejo Pinochet
  26  * @remark Libav merging spearheaded by Kenan Gillet
  27  * @remark Development mentored by Benjamin Larson
  28  */
  29
  30 #include <stddef.h>
  31
  32 #include "libavutil/channel_layout.h"
  33 #include "libavutil/float_dsp.h"
  34 #include "avcodec.h"
  35 #include "internal.h"
  36 #include "get_bits.h"
  37 #include "qcelpdata.h"
  38 #include "celp_filters.h"
  39 #include "acelp_filters.h"
  40 #include "acelp_vectors.h"
  41 #include "lsp.h"
  42
  43 #undef NDEBUG
  44 #include <assert.h>
  45
  46 typedef enum {
  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     GetBitContext     gb;
  57     qcelp_packet_rate bitrate;
  58     QCELPFrame        frame;    /**< unpacked data frame */
  59
  60     uint8_t  erasure_count;
  61     uint8_t  octave_count;      /**< count the consecutive RATE_OCTAVE frames */
  62     float    prev_lspf[10];
  63     float    predictor_lspf[10];/**< LSP predictor for RATE_OCTAVE and I_F_Q */
  64     float    pitch_synthesis_filter_mem[303];
  65     float    pitch_pre_filter_mem[303];
  66     float    rnd_fir_filter_mem[180];
  67     float    formant_mem[170];
  68     float    last_codebook_gain;
  69     int      prev_g1[2];
  70     int      prev_bitrate;
  71     float    pitch_gain[4];
  72     uint8_t  pitch_lag[4];
  73     uint16_t first16bits;
  74     uint8_t  warned_buf_mismatch_bitrate;
  75
  76     /* postfilter */
  77     float    postfilter_synth_mem[10];
  78     float    postfilter_agc_mem;
  79     float    postfilter_tilt_mem;
  80 } QCELPContext;
  81
  82 /**
  83  * Initialize the speech codec according to the specification.
  84  *
  85  * TIA/EIA/IS-733 2.4.9
  86  */
  87 static av_cold int qcelp_decode_init(AVCodecContext *avctx)
  88 {
  89     QCELPContext *q = avctx->priv_data;
  90     int i;
  91
  92     avctx->channels       = 1;
  93     avctx->channel_layout = AV_CH_LAYOUT_MONO;
  94     avctx->sample_fmt     = AV_SAMPLE_FMT_FLT;
  95
  96     for (i = 0; i < 10; i++)
  97         q->prev_lspf[i] = (i + 1) / 11.;
  98
  99     return 0;
 100 }
 101
 102 /**
 103  * Decode the 10 quantized LSP frequencies from the LSPV/LSP
 104  * transmission codes of any bitrate and check for badly received packets.
 105  *
 106  * @param q the context
 107  * @param lspf line spectral pair frequencies
 108  *
 109  * @return 0 on success, -1 if the packet is badly received
 110  *
 111  * TIA/EIA/IS-733 2.4.3.2.6.2-2, 2.4.8.7.3
 112  */
 113 static int decode_lspf(QCELPContext *q, float *lspf)
 114 {
 115     int i;
 116     float tmp_lspf, smooth, erasure_coeff;
 117     const float *predictors;
 118
 119     if (q->bitrate == RATE_OCTAVE || q->bitrate == I_F_Q) {
 120         predictors = q->prev_bitrate != RATE_OCTAVE &&
 121                      q->prev_bitrate != I_F_Q ? q->prev_lspf
 122                                               : q->predictor_lspf;
 123
 124         if (q->bitrate == RATE_OCTAVE) {
 125             q->octave_count++;
 126
 127             for (i = 0; i < 10; i++) {
 128                 q->predictor_lspf[i] =
 129                              lspf[i] = (q->frame.lspv[i] ?  QCELP_LSP_SPREAD_FACTOR
 130                                                          : -QCELP_LSP_SPREAD_FACTOR) +
 131                                         predictors[i] * QCELP_LSP_OCTAVE_PREDICTOR   +
 132                                         (i + 1) * ((1 - QCELP_LSP_OCTAVE_PREDICTOR) / 11);
 133             }
 134             smooth = q->octave_count < 10 ? .875 : 0.1;
 135         } else {
 136             erasure_coeff = QCELP_LSP_OCTAVE_PREDICTOR;
 137
 138             assert(q->bitrate == I_F_Q);
 139
 140             if (q->erasure_count > 1)
 141                 erasure_coeff *= q->erasure_count < 4 ? 0.9 : 0.7;
 142
 143             for (i = 0; i < 10; i++) {
 144                 q->predictor_lspf[i] =
 145                              lspf[i] = (i + 1) * (1 - erasure_coeff) / 11 +
 146                                        erasure_coeff * predictors[i];
 147             }
 148             smooth = 0.125;
 149         }
 150
 151         // Check the stability of the LSP frequencies.
 152         lspf[0] = FFMAX(lspf[0], QCELP_LSP_SPREAD_FACTOR);
 153         for (i = 1; i < 10; i++)
 154             lspf[i] = FFMAX(lspf[i], lspf[i - 1] + QCELP_LSP_SPREAD_FACTOR);
 155
 156         lspf[9] = FFMIN(lspf[9], 1.0 - QCELP_LSP_SPREAD_FACTOR);
 157         for (i = 9; i > 0; i--)
 158             lspf[i - 1] = FFMIN(lspf[i - 1], lspf[i] - QCELP_LSP_SPREAD_FACTOR);
 159
 160         // Low-pass filter the LSP frequencies.
 161         ff_weighted_vector_sumf(lspf, lspf, q->prev_lspf, smooth, 1.0 - smooth, 10);
 162     } else {
 163         q->octave_count = 0;
 164
 165         tmp_lspf = 0.;
 166         for (i = 0; i < 5; i++) {
 167             lspf[2 * i + 0] = tmp_lspf += qcelp_lspvq[i][q->frame.lspv[i]][0] * 0.0001;
 168             lspf[2 * i + 1] = tmp_lspf += qcelp_lspvq[i][q->frame.lspv[i]][1] * 0.0001;
 169         }
 170
 171         // Check for badly received packets.
 172         if (q->bitrate == RATE_QUARTER) {
 173             if (lspf[9] <= .70 || lspf[9] >= .97)
 174                 return -1;
 175             for (i = 3; i < 10; i++)
 176                 if (fabs(lspf[i] - lspf[i - 2]) < .08)
 177                     return -1;
 178         } else {
 179             if (lspf[9] <= .66 || lspf[9] >= .985)
 180                 return -1;
 181             for (i = 4; i < 10; i++)
 182                 if (fabs(lspf[i] - lspf[i - 4]) < .0931)
 183                     return -1;
 184         }
 185     }
 186     return 0;
 187 }
 188
 189 /**
 190  * Convert codebook transmission codes to GAIN and INDEX.
 191  *
 192  * @param q the context
 193  * @param gain array holding the decoded gain
 194  *
 195  * TIA/EIA/IS-733 2.4.6.2
 196  */
 197 static void decode_gain_and_index(QCELPContext *q, float *gain)
 198 {
 199     int i, subframes_count, g1[16];
 200     float slope;
 201
 202     if (q->bitrate >= RATE_QUARTER) {
 203         switch (q->bitrate) {
 204         case RATE_FULL: subframes_count = 16; break;
 205         case RATE_HALF: subframes_count =  4; break;
 206         default:        subframes_count =  5;
 207         }
 208         for (i = 0; i < subframes_count; i++) {
 209             g1[i] = 4 * q->frame.cbgain[i];
 210             if (q->bitrate == RATE_FULL && !((i + 1) & 3)) {
 211                 g1[i] += av_clip((g1[i - 1] + g1[i - 2] + g1[i - 3]) / 3 - 6, 0, 32);
 212             }
 213
 214             gain[i] = qcelp_g12ga[g1[i]];
 215
 216             if (q->frame.cbsign[i]) {
 217                 gain[i] = -gain[i];
 218                 q->frame.cindex[i] = (q->frame.cindex[i] - 89) & 127;
 219             }
 220         }
 221
 222         q->prev_g1[0]         = g1[i - 2];
 223         q->prev_g1[1]         = g1[i - 1];
 224         q->last_codebook_gain = qcelp_g12ga[g1[i - 1]];
 225
 226         if (q->bitrate == RATE_QUARTER) {
 227             // Provide smoothing of the unvoiced excitation energy.
 228             gain[7] =       gain[4];
 229             gain[6] = 0.4 * gain[3] + 0.6 * gain[4];
 230             gain[5] =       gain[3];
 231             gain[4] = 0.8 * gain[2] + 0.2 * gain[3];
 232             gain[3] = 0.2 * gain[1] + 0.8 * gain[2];
 233             gain[2] =       gain[1];
 234             gain[1] = 0.6 * gain[0] + 0.4 * gain[1];
 235         }
 236     } else if (q->bitrate != SILENCE) {
 237         if (q->bitrate == RATE_OCTAVE) {
 238             g1[0] = 2 * q->frame.cbgain[0] +
 239                     av_clip((q->prev_g1[0] + q->prev_g1[1]) / 2 - 5, 0, 54);
 240             subframes_count = 8;
 241         } else {
 242             assert(q->bitrate == I_F_Q);
 243
 244             g1[0] = q->prev_g1[1];
 245             switch (q->erasure_count) {
 246             case 1 : break;
 247             case 2 : g1[0] -= 1; break;
 248             case 3 : g1[0] -= 2; break;
 249             default: g1[0] -= 6;
 250             }
 251             if (g1[0] < 0)
 252                 g1[0] = 0;
 253             subframes_count = 4;
 254         }
 255         // This interpolation is done to produce smoother background noise.
 256         slope = 0.5 * (qcelp_g12ga[g1[0]] - q->last_codebook_gain) / subframes_count;
 257         for (i = 1; i <= subframes_count; i++)
 258                 gain[i - 1] = q->last_codebook_gain + slope * i;
 259
 260         q->last_codebook_gain = gain[i - 2];
 261         q->prev_g1[0]         = q->prev_g1[1];
 262         q->prev_g1[1]         = g1[0];
 263     }
 264 }
 265
 266 /**
 267  * If the received packet is Rate 1/4 a further sanity check is made of the
 268  * codebook gain.
 269  *
 270  * @param cbgain the unpacked cbgain array
 271  * @return -1 if the sanity check fails, 0 otherwise
 272  *
 273  * TIA/EIA/IS-733 2.4.8.7.3
 274  */
 275 static int codebook_sanity_check_for_rate_quarter(const uint8_t *cbgain)
 276 {
 277     int i, diff, prev_diff = 0;
 278
 279     for (i = 1; i < 5; i++) {
 280         diff = cbgain[i] - cbgain[i-1];
 281         if (FFABS(diff) > 10)
 282             return -1;
 283         else if (FFABS(diff - prev_diff) > 12)
 284             return -1;
 285         prev_diff = diff;
 286     }
 287     return 0;
 288 }
 289
 290 /**
 291  * Compute the scaled codebook vector Cdn From INDEX and GAIN
 292  * for all rates.
 293  *
 294  * The specification lacks some information here.
 295  *
 296  * TIA/EIA/IS-733 has an omission on the codebook index determination
 297  * formula for RATE_FULL and RATE_HALF frames at section 2.4.8.1.1. It says
 298  * you have to subtract the decoded index parameter from the given scaled
 299  * codebook vector index 'n' to get the desired circular codebook index, but
 300  * it does not mention that you have to clamp 'n' to [0-9] in order to get
 301  * RI-compliant results.
 302  *
 303  * The reason for this mistake seems to be the fact they forgot to mention you
 304  * have to do these calculations per codebook subframe and adjust given
 305  * equation values accordingly.
 306  *
 307  * @param q the context
 308  * @param gain array holding the 4 pitch subframe gain values
 309  * @param cdn_vector array for the generated scaled codebook vector
 310  */
 311 static void compute_svector(QCELPContext *q, const float *gain,
 312                             float *cdn_vector)
 313 {
 314     int i, j, k;
 315     uint16_t cbseed, cindex;
 316     float *rnd, tmp_gain, fir_filter_value;
 317
 318     switch (q->bitrate) {
 319     case RATE_FULL:
 320         for (i = 0; i < 16; i++) {
 321             tmp_gain = gain[i] * QCELP_RATE_FULL_CODEBOOK_RATIO;
 322             cindex   = -q->frame.cindex[i];
 323             for (j = 0; j < 10; j++)
 324                 *cdn_vector++ = tmp_gain * qcelp_rate_full_codebook[cindex++ & 127];
 325         }
 326         break;
 327     case RATE_HALF:
 328         for (i = 0; i < 4; i++) {
 329             tmp_gain = gain[i] * QCELP_RATE_HALF_CODEBOOK_RATIO;
 330             cindex   = -q->frame.cindex[i];
 331             for (j = 0; j < 40; j++)
 332                 *cdn_vector++ = tmp_gain * qcelp_rate_half_codebook[cindex++ & 127];
 333         }
 334         break;
 335     case RATE_QUARTER:
 336         cbseed = (0x0003 & q->frame.lspv[4]) << 14 |
 337                  (0x003F & q->frame.lspv[3]) <<  8 |
 338                  (0x0060 & q->frame.lspv[2]) <<  1 |
 339                  (0x0007 & q->frame.lspv[1]) <<  3 |
 340                  (0x0038 & q->frame.lspv[0]) >>  3;
 341         rnd    = q->rnd_fir_filter_mem + 20;
 342         for (i = 0; i < 8; i++) {
 343             tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
 344             for (k = 0; k < 20; k++) {
 345                 cbseed = 521 * cbseed + 259;
 346                 *rnd   = (int16_t) cbseed;
 347
 348                     // FIR filter
 349                 fir_filter_value = 0.0;
 350                 for (j = 0; j < 10; j++)
 351                     fir_filter_value += qcelp_rnd_fir_coefs[j] *
 352                                         (rnd[-j] + rnd[-20+j]);
 353
 354                 fir_filter_value += qcelp_rnd_fir_coefs[10] * rnd[-10];
 355                 *cdn_vector++     = tmp_gain * fir_filter_value;
 356                 rnd++;
 357             }
 358         }
 359         memcpy(q->rnd_fir_filter_mem, q->rnd_fir_filter_mem + 160,
 360                20 * sizeof(float));
 361         break;
 362     case RATE_OCTAVE:
 363         cbseed = q->first16bits;
 364         for (i = 0; i < 8; i++) {
 365             tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
 366             for (j = 0; j < 20; j++) {
 367                 cbseed        = 521 * cbseed + 259;
 368                 *cdn_vector++ = tmp_gain * (int16_t) cbseed;
 369             }
 370         }
 371         break;
 372     case I_F_Q:
 373         cbseed = -44; // random codebook index
 374         for (i = 0; i < 4; i++) {
 375             tmp_gain = gain[i] * QCELP_RATE_FULL_CODEBOOK_RATIO;
 376             for (j = 0; j < 40; j++)
 377                 *cdn_vector++ = tmp_gain * qcelp_rate_full_codebook[cbseed++ & 127];
 378         }
 379         break;
 380     case SILENCE:
 381         memset(cdn_vector, 0, 160 * sizeof(float));
 382         break;
 383     }
 384 }
 385
 386 /**
 387  * Apply generic gain control.
 388  *
 389  * @param v_out output vector
 390  * @param v_in gain-controlled vector
 391  * @param v_ref vector to control gain of
 392  *
 393  * TIA/EIA/IS-733 2.4.8.3, 2.4.8.6
 394  */
 395 static void apply_gain_ctrl(float *v_out, const float *v_ref, const float *v_in)
 396 {
 397     int i;
 398
 399     for (i = 0; i < 160; i += 40) {
 400         float res = avpriv_scalarproduct_float_c(v_ref + i, v_ref + i, 40);
 401         ff_scale_vector_to_given_sum_of_squares(v_out + i, v_in + i, res, 40);
 402     }
 403 }
 404
 405 /**
 406  * Apply filter in pitch-subframe steps.
 407  *
 408  * @param memory buffer for the previous state of the filter
 409  *        - must be able to contain 303 elements
 410  *        - the 143 first elements are from the previous state
 411  *        - the next 160 are for output
 412  * @param v_in input filter vector
 413  * @param gain per-subframe gain array, each element is between 0.0 and 2.0
 414  * @param lag per-subframe lag array, each element is
 415  *        - between 16 and 143 if its corresponding pfrac is 0,
 416  *        - between 16 and 139 otherwise
 417  * @param pfrac per-subframe boolean array, 1 if the lag is fractional, 0
 418  *        otherwise
 419  *
 420  * @return filter output vector
 421  */
 422 static const float *do_pitchfilter(float memory[303], const float v_in[160],
 423                                    const float gain[4], const uint8_t *lag,
 424                                    const uint8_t pfrac[4])
 425 {
 426     int i, j;
 427     float *v_lag, *v_out;
 428     const float *v_len;
 429
 430     v_out = memory + 143; // Output vector starts at memory[143].
 431
 432     for (i = 0; i < 4; i++) {
 433         if (gain[i]) {
 434             v_lag = memory + 143 + 40 * i - lag[i];
 435             for (v_len = v_in + 40; v_in < v_len; v_in++) {
 436                 if (pfrac[i]) { // If it is a fractional lag...
 437                     for (j = 0, *v_out = 0.; j < 4; j++)
 438                         *v_out += qcelp_hammsinc_table[j] * (v_lag[j - 4] + v_lag[3 - j]);
 439                 } else
 440                     *v_out = *v_lag;
 441
 442                 *v_out = *v_in + gain[i] * *v_out;
 443
 444                 v_lag++;
 445                 v_out++;
 446             }
 447         } else {
 448             memcpy(v_out, v_in, 40 * sizeof(float));
 449             v_in  += 40;
 450             v_out += 40;
 451         }
 452     }
 453
 454     memmove(memory, memory + 160, 143 * sizeof(float));
 455     return memory + 143;
 456 }
 457
 458 /**
 459  * Apply pitch synthesis filter and pitch prefilter to the scaled codebook vector.
 460  * TIA/EIA/IS-733 2.4.5.2, 2.4.8.7.2
 461  *
 462  * @param q the context
 463  * @param cdn_vector the scaled codebook vector
 464  */
 465 static void apply_pitch_filters(QCELPContext *q, float *cdn_vector)
 466 {
 467     int i;
 468     const float *v_synthesis_filtered, *v_pre_filtered;
 469
 470     if (q->bitrate >= RATE_HALF || q->bitrate == SILENCE ||
 471         (q->bitrate == I_F_Q && (q->prev_bitrate >= RATE_HALF))) {
 472
 473         if (q->bitrate >= RATE_HALF) {
 474             // Compute gain & lag for the whole frame.
 475             for (i = 0; i < 4; i++) {
 476                 q->pitch_gain[i] = q->frame.plag[i] ? (q->frame.pgain[i] + 1) * 0.25 : 0.0;
 477
 478                 q->pitch_lag[i] = q->frame.plag[i] + 16;
 479             }
 480         } else {
 481             float max_pitch_gain;
 482
 483             if (q->bitrate == I_F_Q) {
 484                   if (q->erasure_count < 3)
 485                       max_pitch_gain = 0.9 - 0.3 * (q->erasure_count - 1);
 486                   else
 487                       max_pitch_gain = 0.0;
 488             } else {
 489                 assert(q->bitrate == SILENCE);
 490                 max_pitch_gain = 1.0;
 491             }
 492             for (i = 0; i < 4; i++)
 493                 q->pitch_gain[i] = FFMIN(q->pitch_gain[i], max_pitch_gain);
 494
 495             memset(q->frame.pfrac, 0, sizeof(q->frame.pfrac));
 496         }
 497
 498         // pitch synthesis filter
 499         v_synthesis_filtered = do_pitchfilter(q->pitch_synthesis_filter_mem,
 500                                               cdn_vector, q->pitch_gain,
 501                                               q->pitch_lag, q->frame.pfrac);
 502
 503         // pitch prefilter update
 504         for (i = 0; i < 4; i++)
 505             q->pitch_gain[i] = 0.5 * FFMIN(q->pitch_gain[i], 1.0);
 506
 507         v_pre_filtered       = do_pitchfilter(q->pitch_pre_filter_mem,
 508                                               v_synthesis_filtered,
 509                                               q->pitch_gain, q->pitch_lag,
 510                                               q->frame.pfrac);
 511
 512         apply_gain_ctrl(cdn_vector, v_synthesis_filtered, v_pre_filtered);
 513     } else {
 514         memcpy(q->pitch_synthesis_filter_mem, cdn_vector + 17, 143 * sizeof(float));
 515         memcpy(q->pitch_pre_filter_mem, cdn_vector + 17, 143 * sizeof(float));
 516         memset(q->pitch_gain, 0, sizeof(q->pitch_gain));
 517         memset(q->pitch_lag,  0, sizeof(q->pitch_lag));
 518     }
 519 }
 520
 521 /**
 522  * Reconstruct LPC coefficients from the line spectral pair frequencies
 523  * and perform bandwidth expansion.
 524  *
 525  * @param lspf line spectral pair frequencies
 526  * @param lpc linear predictive coding coefficients
 527  *
 528  * @note: bandwidth_expansion_coeff could be precalculated into a table
 529  *        but it seems to be slower on x86
 530  *
 531  * TIA/EIA/IS-733 2.4.3.3.5
 532  */
 533 static void lspf2lpc(const float *lspf, float *lpc)
 534 {
 535     double lsp[10];
 536     double bandwidth_expansion_coeff = QCELP_BANDWIDTH_EXPANSION_COEFF;
 537     int i;
 538
 539     for (i = 0; i < 10; i++)
 540         lsp[i] = cos(M_PI * lspf[i]);
 541
 542     ff_acelp_lspd2lpc(lsp, lpc, 5);
 543
 544     for (i = 0; i < 10; i++) {
 545         lpc[i]                    *= bandwidth_expansion_coeff;
 546         bandwidth_expansion_coeff *= QCELP_BANDWIDTH_EXPANSION_COEFF;
 547     }
 548 }
 549
 550 /**
 551  * Interpolate LSP frequencies and compute LPC coefficients
 552  * for a given bitrate & pitch subframe.
 553  *
 554  * TIA/EIA/IS-733 2.4.3.3.4, 2.4.8.7.2
 555  *
 556  * @param q the context
 557  * @param curr_lspf LSP frequencies vector of the current frame
 558  * @param lpc float vector for the resulting LPC
 559  * @param subframe_num frame number in decoded stream
 560  */
 561 static void interpolate_lpc(QCELPContext *q, const float *curr_lspf,
 562                             float *lpc, const int subframe_num)
 563 {
 564     float interpolated_lspf[10];
 565     float weight;
 566
 567     if (q->bitrate >= RATE_QUARTER)
 568         weight = 0.25 * (subframe_num + 1);
 569     else if (q->bitrate == RATE_OCTAVE && !subframe_num)
 570         weight = 0.625;
 571     else
 572         weight = 1.0;
 573
 574     if (weight != 1.0) {
 575         ff_weighted_vector_sumf(interpolated_lspf, curr_lspf, q->prev_lspf,
 576                                 weight, 1.0 - weight, 10);
 577         lspf2lpc(interpolated_lspf, lpc);
 578     } else if (q->bitrate >= RATE_QUARTER ||
 579                (q->bitrate == I_F_Q && !subframe_num))
 580         lspf2lpc(curr_lspf, lpc);
 581     else if (q->bitrate == SILENCE && !subframe_num)
 582         lspf2lpc(q->prev_lspf, lpc);
 583 }
 584
 585 static qcelp_packet_rate buf_size2bitrate(const int buf_size)
 586 {
 587     switch (buf_size) {
 588     case 35: return RATE_FULL;
 589     case 17: return RATE_HALF;
 590     case  8: return RATE_QUARTER;
 591     case  4: return RATE_OCTAVE;
 592     case  1: return SILENCE;
 593     }
 594
 595     return I_F_Q;
 596 }
 597
 598 /**
 599  * Determine the bitrate from the frame size and/or the first byte of the frame.
 600  *
 601  * @param avctx the AV codec context
 602  * @param buf_size length of the buffer
 603  * @param buf the bufffer
 604  *
 605  * @return the bitrate on success,
 606  *         I_F_Q  if the bitrate cannot be satisfactorily determined
 607  *
 608  * TIA/EIA/IS-733 2.4.8.7.1
 609  */
 610 static qcelp_packet_rate determine_bitrate(AVCodecContext *avctx,
 611                                            const int buf_size,
 612                                            const uint8_t **buf)
 613 {
 614     qcelp_packet_rate bitrate;
 615
 616     if ((bitrate = buf_size2bitrate(buf_size)) >= 0) {
 617         if (bitrate > **buf) {
 618             QCELPContext *q = avctx->priv_data;
 619             if (!q->warned_buf_mismatch_bitrate) {
 620             av_log(avctx, AV_LOG_WARNING,
 621                    "Claimed bitrate and buffer size mismatch.\n");
 622                 q->warned_buf_mismatch_bitrate = 1;
 623             }
 624             bitrate = **buf;
 625         } else if (bitrate < **buf) {
 626             av_log(avctx, AV_LOG_ERROR,
 627                    "Buffer is too small for the claimed bitrate.\n");
 628             return I_F_Q;
 629         }
 630         (*buf)++;
 631     } else if ((bitrate = buf_size2bitrate(buf_size + 1)) >= 0) {
 632         av_log(avctx, AV_LOG_WARNING,
 633                "Bitrate byte is missing, guessing the bitrate from packet size.\n");
 634     } else
 635         return I_F_Q;
 636
 637     if (bitrate == SILENCE) {
 638         //FIXME: Remove experimental warning when tested with samples.
 639         av_log_ask_for_sample(avctx, "'Blank frame handling is experimental.");
 640     }
 641     return bitrate;
 642 }
 643
 644 static void warn_insufficient_frame_quality(AVCodecContext *avctx,
 645                                             const char *message)
 646 {
 647     av_log(avctx, AV_LOG_WARNING, "Frame #%d, IFQ: %s\n",
 648            avctx->frame_number, message);
 649 }
 650
 651 static void postfilter(QCELPContext *q, float *samples, float *lpc)
 652 {
 653     static const float pow_0_775[10] = {
 654         0.775000, 0.600625, 0.465484, 0.360750, 0.279582,
 655         0.216676, 0.167924, 0.130141, 0.100859, 0.078166
 656     }, pow_0_625[10] = {
 657         0.625000, 0.390625, 0.244141, 0.152588, 0.095367,
 658         0.059605, 0.037253, 0.023283, 0.014552, 0.009095
 659     };
 660     float lpc_s[10], lpc_p[10], pole_out[170], zero_out[160];
 661     int n;
 662
 663     for (n = 0; n < 10; n++) {
 664         lpc_s[n] = lpc[n] * pow_0_625[n];
 665         lpc_p[n] = lpc[n] * pow_0_775[n];
 666     }
 667
 668     ff_celp_lp_zero_synthesis_filterf(zero_out, lpc_s,
 669                                       q->formant_mem + 10, 160, 10);
 670     memcpy(pole_out, q->postfilter_synth_mem, sizeof(float) * 10);
 671     ff_celp_lp_synthesis_filterf(pole_out + 10, lpc_p, zero_out, 160, 10);
 672     memcpy(q->postfilter_synth_mem, pole_out + 160, sizeof(float) * 10);
 673
 674     ff_tilt_compensation(&q->postfilter_tilt_mem, 0.3, pole_out + 10, 160);
 675
 676     ff_adaptive_gain_control(samples, pole_out + 10,
 677                              avpriv_scalarproduct_float_c(q->formant_mem + 10,
 678                                                           q->formant_mem + 10,
 679                                                           160),
 680                              160, 0.9375, &q->postfilter_agc_mem);
 681 }
 682
 683 static int qcelp_decode_frame(AVCodecContext *avctx, void *data,
 684                               int *got_frame_ptr, AVPacket *avpkt)
 685 {
 686     const uint8_t *buf = avpkt->data;
 687     int buf_size       = avpkt->size;
 688     QCELPContext *q    = avctx->priv_data;
 689     AVFrame *frame     = data;
 690     float *outbuffer;
 691     int   i, ret;
 692     float quantized_lspf[10], lpc[10];
 693     float gain[16];
 694     float *formant_mem;
 695
 696     /* get output buffer */
 697     frame->nb_samples = 160;
 698     if ((ret = ff_get_buffer(avctx, frame)) < 0) {
 699         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 700         return ret;
 701     }
 702     outbuffer = (float *)frame->data[0];
 703
 704     if ((q->bitrate = determine_bitrate(avctx, buf_size, &buf)) == I_F_Q) {
 705         warn_insufficient_frame_quality(avctx, "bitrate cannot be determined.");
 706         goto erasure;
 707     }
 708
 709     if (q->bitrate == RATE_OCTAVE &&
 710         (q->first16bits = AV_RB16(buf)) == 0xFFFF) {
 711         warn_insufficient_frame_quality(avctx, "Bitrate is 1/8 and first 16 bits are on.");
 712         goto erasure;
 713     }
 714
 715     if (q->bitrate > SILENCE) {
 716         const QCELPBitmap *bitmaps     = qcelp_unpacking_bitmaps_per_rate[q->bitrate];
 717         const QCELPBitmap *bitmaps_end = qcelp_unpacking_bitmaps_per_rate[q->bitrate] +
 718                                          qcelp_unpacking_bitmaps_lengths[q->bitrate];
 719         uint8_t *unpacked_data         = (uint8_t *)&q->frame;
 720
 721         init_get_bits(&q->gb, buf, 8 * buf_size);
 722
 723         memset(&q->frame, 0, sizeof(QCELPFrame));
 724
 725         for (; bitmaps < bitmaps_end; bitmaps++)
 726             unpacked_data[bitmaps->index] |= get_bits(&q->gb, bitmaps->bitlen) << bitmaps->bitpos;
 727
 728         // Check for erasures/blanks on rates 1, 1/4 and 1/8.
 729         if (q->frame.reserved) {
 730             warn_insufficient_frame_quality(avctx, "Wrong data in reserved frame area.");
 731             goto erasure;
 732         }
 733         if (q->bitrate == RATE_QUARTER &&
 734             codebook_sanity_check_for_rate_quarter(q->frame.cbgain)) {
 735             warn_insufficient_frame_quality(avctx, "Codebook gain sanity check failed.");
 736             goto erasure;
 737         }
 738
 739         if (q->bitrate >= RATE_HALF) {
 740             for (i = 0; i < 4; i++) {
 741                 if (q->frame.pfrac[i] && q->frame.plag[i] >= 124) {
 742                     warn_insufficient_frame_quality(avctx, "Cannot initialize pitch filter.");
 743                     goto erasure;
 744                 }
 745             }
 746         }
 747     }
 748
 749     decode_gain_and_index(q, gain);
 750     compute_svector(q, gain, outbuffer);
 751
 752     if (decode_lspf(q, quantized_lspf) < 0) {
 753         warn_insufficient_frame_quality(avctx, "Badly received packets in frame.");
 754         goto erasure;
 755     }
 756
 757     apply_pitch_filters(q, outbuffer);
 758
 759     if (q->bitrate == I_F_Q) {
 760 erasure:
 761         q->bitrate = I_F_Q;
 762         q->erasure_count++;
 763         decode_gain_and_index(q, gain);
 764         compute_svector(q, gain, outbuffer);
 765         decode_lspf(q, quantized_lspf);
 766         apply_pitch_filters(q, outbuffer);
 767     } else
 768         q->erasure_count = 0;
 769
 770     formant_mem = q->formant_mem + 10;
 771     for (i = 0; i < 4; i++) {
 772         interpolate_lpc(q, quantized_lspf, lpc, i);
 773         ff_celp_lp_synthesis_filterf(formant_mem, lpc, outbuffer + i * 40, 40, 10);
 774         formant_mem += 40;
 775     }
 776
 777     // postfilter, as per TIA/EIA/IS-733 2.4.8.6
 778     postfilter(q, outbuffer, lpc);
 779
 780     memcpy(q->formant_mem, q->formant_mem + 160, 10 * sizeof(float));
 781
 782     memcpy(q->prev_lspf, quantized_lspf, sizeof(q->prev_lspf));
 783     q->prev_bitrate  = q->bitrate;
 784
 785     *got_frame_ptr = 1;
 786
 787     return buf_size;
 788 }
 789
 790 AVCodec ff_qcelp_decoder = {
 791     .name           = "qcelp",
 792     .type           = AVMEDIA_TYPE_AUDIO,
 793     .id             = AV_CODEC_ID_QCELP,
 794     .init           = qcelp_decode_init,
 795     .decode         = qcelp_decode_frame,
 796     .capabilities   = CODEC_CAP_DR1,
 797     .priv_data_size = sizeof(QCELPContext),
 798     .long_name      = NULL_IF_CONFIG_SMALL("QCELP / PureVoice"),
 799 };