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
  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 "libavutil/avassert.h"
  31 #include "libavutil/channel_layout.h"
  32 #include "libavutil/float_dsp.h"
  33 #include "avcodec.h"
  34 #include "codec_internal.h"
  35 #include "decode.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 typedef enum {
  44     I_F_Q = -1,    /**< insufficient frame quality */
  45     SILENCE,
  46     RATE_OCTAVE,
  47     RATE_QUARTER,
  48     RATE_HALF,
  49     RATE_FULL
  50 } qcelp_packet_rate;
  51
  52 typedef struct QCELPContext {
  53     GetBitContext     gb;
  54     qcelp_packet_rate bitrate;
  55     QCELPFrame        frame;    /**< unpacked data frame */
  56
  57     uint8_t  erasure_count;
  58     uint8_t  octave_count;      /**< count the consecutive RATE_OCTAVE frames */
  59     float    prev_lspf[10];
  60     float    predictor_lspf[10];/**< LSP predictor for RATE_OCTAVE and I_F_Q */
  61     float    pitch_synthesis_filter_mem[303];
  62     float    pitch_pre_filter_mem[303];
  63     float    rnd_fir_filter_mem[180];
  64     float    formant_mem[170];
  65     float    last_codebook_gain;
  66     int      prev_g1[2];
  67     int      prev_bitrate;
  68     float    pitch_gain[4];
  69     uint8_t  pitch_lag[4];
  70     uint16_t first16bits;
  71     uint8_t  warned_buf_mismatch_bitrate;
  72
  73     /* postfilter */
  74     float    postfilter_synth_mem[10];
  75     float    postfilter_agc_mem;
  76     float    postfilter_tilt_mem;
  77 } QCELPContext;
  78
  79 /**
  80  * Initialize the speech codec according to the specification.
  81  *
  82  * TIA/EIA/IS-733 2.4.9
  83  */
  84 static av_cold int qcelp_decode_init(AVCodecContext *avctx)
  85 {
  86     QCELPContext *q = avctx->priv_data;
  87     int i;
  88
  89     av_channel_layout_uninit(&avctx->ch_layout);
  90     avctx->ch_layout      = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;
  91     avctx->sample_fmt     = AV_SAMPLE_FMT_FLT;
  92
  93     for (i = 0; i < 10; i++)
  94         q->prev_lspf[i] = (i + 1) / 11.0;
  95
  96     return 0;
  97 }
  98
  99 /**
 100  * Decode the 10 quantized LSP frequencies from the LSPV/LSP
 101  * transmission codes of any bitrate and check for badly received packets.
 102  *
 103  * @param q the context
 104  * @param lspf line spectral pair frequencies
 105  *
 106  * @return 0 on success, -1 if the packet is badly received
 107  *
 108  * TIA/EIA/IS-733 2.4.3.2.6.2-2, 2.4.8.7.3
 109  */
 110 static int decode_lspf(QCELPContext *q, float *lspf)
 111 {
 112     int i;
 113     float tmp_lspf, smooth, erasure_coeff;
 114     const float *predictors;
 115
 116     if (q->bitrate == RATE_OCTAVE || q->bitrate == I_F_Q) {
 117         predictors = q->prev_bitrate != RATE_OCTAVE &&
 118                      q->prev_bitrate != I_F_Q ? q->prev_lspf
 119                                               : q->predictor_lspf;
 120
 121         if (q->bitrate == RATE_OCTAVE) {
 122             q->octave_count++;
 123
 124             for (i = 0; i < 10; i++) {
 125                 q->predictor_lspf[i] =
 126                              lspf[i] = (q->frame.lspv[i] ?  QCELP_LSP_SPREAD_FACTOR
 127                                                          : -QCELP_LSP_SPREAD_FACTOR) +
 128                                         predictors[i] * QCELP_LSP_OCTAVE_PREDICTOR   +
 129                                         (i + 1) * ((1 - QCELP_LSP_OCTAVE_PREDICTOR) / 11);
 130             }
 131             smooth = q->octave_count < 10 ? .875 : 0.1;
 132         } else {
 133             erasure_coeff = QCELP_LSP_OCTAVE_PREDICTOR;
 134
 135             av_assert2(q->bitrate == I_F_Q);
 136
 137             if (q->erasure_count > 1)
 138                 erasure_coeff *= q->erasure_count < 4 ? 0.9 : 0.7;
 139
 140             for (i = 0; i < 10; i++) {
 141                 q->predictor_lspf[i] =
 142                              lspf[i] = (i + 1) * (1 - erasure_coeff) / 11 +
 143                                        erasure_coeff * predictors[i];
 144             }
 145             smooth = 0.125;
 146         }
 147
 148         // Check the stability of the LSP frequencies.
 149         lspf[0] = FFMAX(lspf[0], QCELP_LSP_SPREAD_FACTOR);
 150         for (i = 1; i < 10; i++)
 151             lspf[i] = FFMAX(lspf[i], lspf[i - 1] + QCELP_LSP_SPREAD_FACTOR);
 152
 153         lspf[9] = FFMIN(lspf[9], 1.0 - QCELP_LSP_SPREAD_FACTOR);
 154         for (i = 9; i > 0; i--)
 155             lspf[i - 1] = FFMIN(lspf[i - 1], lspf[i] - QCELP_LSP_SPREAD_FACTOR);
 156
 157         // Low-pass filter the LSP frequencies.
 158         ff_weighted_vector_sumf(lspf, lspf, q->prev_lspf, smooth, 1.0 - smooth, 10);
 159     } else {
 160         q->octave_count = 0;
 161
 162         tmp_lspf = 0.0;
 163         for (i = 0; i < 5; i++) {
 164             lspf[2 * i + 0] = tmp_lspf += qcelp_lspvq[i][q->frame.lspv[i]][0] * 0.0001;
 165             lspf[2 * i + 1] = tmp_lspf += qcelp_lspvq[i][q->frame.lspv[i]][1] * 0.0001;
 166         }
 167
 168         // Check for badly received packets.
 169         if (q->bitrate == RATE_QUARTER) {
 170             if (lspf[9] <= .70 || lspf[9] >= .97)
 171                 return -1;
 172             for (i = 3; i < 10; i++)
 173                 if (fabs(lspf[i] - lspf[i - 2]) < .08)
 174                     return -1;
 175         } else {
 176             if (lspf[9] <= .66 || lspf[9] >= .985)
 177                 return -1;
 178             for (i = 4; i < 10; i++)
 179                 if (fabs(lspf[i] - lspf[i - 4]) < .0931)
 180                     return -1;
 181         }
 182     }
 183     return 0;
 184 }
 185
 186 /**
 187  * Convert codebook transmission codes to GAIN and INDEX.
 188  *
 189  * @param q the context
 190  * @param gain array holding the decoded gain
 191  *
 192  * TIA/EIA/IS-733 2.4.6.2
 193  */
 194 static void decode_gain_and_index(QCELPContext *q, float *gain)
 195 {
 196     int i, subframes_count, g1[16];
 197     float slope;
 198
 199     if (q->bitrate >= RATE_QUARTER) {
 200         switch (q->bitrate) {
 201         case RATE_FULL: subframes_count = 16; break;
 202         case RATE_HALF: subframes_count =  4; break;
 203         default:        subframes_count =  5;
 204         }
 205         for (i = 0; i < subframes_count; i++) {
 206             g1[i] = 4 * q->frame.cbgain[i];
 207             if (q->bitrate == RATE_FULL && !((i + 1) & 3)) {
 208                 g1[i] += av_clip((g1[i - 1] + g1[i - 2] + g1[i - 3]) / 3 - 6, 0, 32);
 209             }
 210
 211             gain[i] = qcelp_g12ga[g1[i]];
 212
 213             if (q->frame.cbsign[i]) {
 214                 gain[i] = -gain[i];
 215                 q->frame.cindex[i] = (q->frame.cindex[i] - 89) & 127;
 216             }
 217         }
 218
 219         q->prev_g1[0]         = g1[i - 2];
 220         q->prev_g1[1]         = g1[i - 1];
 221         q->last_codebook_gain = qcelp_g12ga[g1[i - 1]];
 222
 223         if (q->bitrate == RATE_QUARTER) {
 224             // Provide smoothing of the unvoiced excitation energy.
 225             gain[7] =       gain[4];
 226             gain[6] = 0.4 * gain[3] + 0.6 * gain[4];
 227             gain[5] =       gain[3];
 228             gain[4] = 0.8 * gain[2] + 0.2 * gain[3];
 229             gain[3] = 0.2 * gain[1] + 0.8 * gain[2];
 230             gain[2] =       gain[1];
 231             gain[1] = 0.6 * gain[0] + 0.4 * gain[1];
 232         }
 233     } else if (q->bitrate != SILENCE) {
 234         if (q->bitrate == RATE_OCTAVE) {
 235             g1[0] = 2 * q->frame.cbgain[0] +
 236                     av_clip((q->prev_g1[0] + q->prev_g1[1]) / 2 - 5, 0, 54);
 237             subframes_count = 8;
 238         } else {
 239             av_assert2(q->bitrate == I_F_Q);
 240
 241             g1[0] = q->prev_g1[1];
 242             switch (q->erasure_count) {
 243             case 1 : break;
 244             case 2 : g1[0] -= 1; break;
 245             case 3 : g1[0] -= 2; break;
 246             default: g1[0] -= 6;
 247             }
 248             if (g1[0] < 0)
 249                 g1[0] = 0;
 250             subframes_count = 4;
 251         }
 252         // This interpolation is done to produce smoother background noise.
 253         slope = 0.5 * (qcelp_g12ga[g1[0]] - q->last_codebook_gain) / subframes_count;
 254         for (i = 1; i <= subframes_count; i++)
 255                 gain[i - 1] = q->last_codebook_gain + slope * i;
 256
 257         q->last_codebook_gain = gain[i - 2];
 258         q->prev_g1[0]         = q->prev_g1[1];
 259         q->prev_g1[1]         = g1[0];
 260     }
 261 }
 262
 263 /**
 264  * If the received packet is Rate 1/4 a further sanity check is made of the
 265  * codebook gain.
 266  *
 267  * @param cbgain the unpacked cbgain array
 268  * @return -1 if the sanity check fails, 0 otherwise
 269  *
 270  * TIA/EIA/IS-733 2.4.8.7.3
 271  */
 272 static int codebook_sanity_check_for_rate_quarter(const uint8_t *cbgain)
 273 {
 274     int i, diff, prev_diff = 0;
 275
 276     for (i = 1; i < 5; i++) {
 277         diff = cbgain[i] - cbgain[i-1];
 278         if (FFABS(diff) > 10)
 279             return -1;
 280         else if (FFABS(diff - prev_diff) > 12)
 281             return -1;
 282         prev_diff = diff;
 283     }
 284     return 0;
 285 }
 286
 287 /**
 288  * Compute the scaled codebook vector Cdn From INDEX and GAIN
 289  * for all rates.
 290  *
 291  * The specification lacks some information here.
 292  *
 293  * TIA/EIA/IS-733 has an omission on the codebook index determination
 294  * formula for RATE_FULL and RATE_HALF frames at section 2.4.8.1.1. It says
 295  * you have to subtract the decoded index parameter from the given scaled
 296  * codebook vector index 'n' to get the desired circular codebook index, but
 297  * it does not mention that you have to clamp 'n' to [0-9] in order to get
 298  * RI-compliant results.
 299  *
 300  * The reason for this mistake seems to be the fact they forgot to mention you
 301  * have to do these calculations per codebook subframe and adjust given
 302  * equation values accordingly.
 303  *
 304  * @param q the context
 305  * @param gain array holding the 4 pitch subframe gain values
 306  * @param cdn_vector array for the generated scaled codebook vector
 307  */
 308 static void compute_svector(QCELPContext *q, const float *gain,
 309                             float *cdn_vector)
 310 {
 311     int i, j, k;
 312     uint16_t cbseed, cindex;
 313     float *rnd, tmp_gain, fir_filter_value;
 314
 315     switch (q->bitrate) {
 316     case RATE_FULL:
 317         for (i = 0; i < 16; i++) {
 318             tmp_gain = gain[i] * QCELP_RATE_FULL_CODEBOOK_RATIO;
 319             cindex   = -q->frame.cindex[i];
 320             for (j = 0; j < 10; j++)
 321                 *cdn_vector++ = tmp_gain *
 322                                 qcelp_rate_full_codebook[cindex++ & 127];
 323         }
 324         break;
 325     case RATE_HALF:
 326         for (i = 0; i < 4; i++) {
 327             tmp_gain = gain[i] * QCELP_RATE_HALF_CODEBOOK_RATIO;
 328             cindex   = -q->frame.cindex[i];
 329             for (j = 0; j < 40; j++)
 330                 *cdn_vector++ = tmp_gain *
 331                                 qcelp_rate_half_codebook[cindex++ & 127];
 332         }
 333         break;
 334     case RATE_QUARTER:
 335         cbseed = (0x0003 & q->frame.lspv[4]) << 14 |
 336                  (0x003F & q->frame.lspv[3]) <<  8 |
 337                  (0x0060 & q->frame.lspv[2]) <<  1 |
 338                  (0x0007 & q->frame.lspv[1]) <<  3 |
 339                  (0x0038 & q->frame.lspv[0]) >>  3;
 340         rnd    = q->rnd_fir_filter_mem + 20;
 341         for (i = 0; i < 8; i++) {
 342             tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
 343             for (k = 0; k < 20; k++) {
 344                 cbseed = 521 * cbseed + 259;
 345                 *rnd   = (int16_t) cbseed;
 346
 347                     // FIR filter
 348                 fir_filter_value = 0.0;
 349                 for (j = 0; j < 10; j++)
 350                     fir_filter_value += qcelp_rnd_fir_coefs[j] *
 351                                         (rnd[-j] + rnd[-20+j]);
 352
 353                 fir_filter_value += qcelp_rnd_fir_coefs[10] * rnd[-10];
 354                 *cdn_vector++     = tmp_gain * fir_filter_value;
 355                 rnd++;
 356             }
 357         }
 358         memcpy(q->rnd_fir_filter_mem, q->rnd_fir_filter_mem + 160,
 359                20 * sizeof(float));
 360         break;
 361     case RATE_OCTAVE:
 362         cbseed = q->first16bits;
 363         for (i = 0; i < 8; i++) {
 364             tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
 365             for (j = 0; j < 20; j++) {
 366                 cbseed        = 521 * cbseed + 259;
 367                 *cdn_vector++ = tmp_gain * (int16_t) cbseed;
 368             }
 369         }
 370         break;
 371     case I_F_Q:
 372         cbseed = -44; // random codebook index
 373         for (i = 0; i < 4; i++) {
 374             tmp_gain = gain[i] * QCELP_RATE_FULL_CODEBOOK_RATIO;
 375             for (j = 0; j < 40; j++)
 376                 *cdn_vector++ = tmp_gain *
 377                                 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 = 0.0; j < 4; j++)
 438                         *v_out += qcelp_hammsinc_table[j] *
 439                                   (v_lag[j - 4] + v_lag[3 - j]);
 440                 } else
 441                     *v_out = *v_lag;
 442
 443                 *v_out = *v_in + gain[i] * *v_out;
 444
 445                 v_lag++;
 446                 v_out++;
 447             }
 448         } else {
 449             memcpy(v_out, v_in, 40 * sizeof(float));
 450             v_in  += 40;
 451             v_out += 40;
 452         }
 453     }
 454
 455     memmove(memory, memory + 160, 143 * sizeof(float));
 456     return memory + 143;
 457 }
 458
 459 /**
 460  * Apply pitch synthesis filter and pitch prefilter to the scaled codebook vector.
 461  * TIA/EIA/IS-733 2.4.5.2, 2.4.8.7.2
 462  *
 463  * @param q the context
 464  * @param cdn_vector the scaled codebook vector
 465  */
 466 static void apply_pitch_filters(QCELPContext *q, float *cdn_vector)
 467 {
 468     int i;
 469     const float *v_synthesis_filtered, *v_pre_filtered;
 470
 471     if (q->bitrate >= RATE_HALF || q->bitrate == SILENCE ||
 472         (q->bitrate == I_F_Q && (q->prev_bitrate >= RATE_HALF))) {
 473
 474         if (q->bitrate >= RATE_HALF) {
 475             // Compute gain & lag for the whole frame.
 476             for (i = 0; i < 4; i++) {
 477                 q->pitch_gain[i] = q->frame.plag[i] ? (q->frame.pgain[i] + 1) * 0.25 : 0.0;
 478
 479                 q->pitch_lag[i] = q->frame.plag[i] + 16;
 480             }
 481         } else {
 482             float max_pitch_gain;
 483
 484             if (q->bitrate == I_F_Q) {
 485                   if (q->erasure_count < 3)
 486                       max_pitch_gain = 0.9 - 0.3 * (q->erasure_count - 1);
 487                   else
 488                       max_pitch_gain = 0.0;
 489             } else {
 490                 av_assert2(q->bitrate == SILENCE);
 491                 max_pitch_gain = 1.0;
 492             }
 493             for (i = 0; i < 4; i++)
 494                 q->pitch_gain[i] = FFMIN(q->pitch_gain[i], max_pitch_gain);
 495
 496             memset(q->frame.pfrac, 0, sizeof(q->frame.pfrac));
 497         }
 498
 499         // pitch synthesis filter
 500         v_synthesis_filtered = do_pitchfilter(q->pitch_synthesis_filter_mem,
 501                                               cdn_vector, q->pitch_gain,
 502                                               q->pitch_lag, q->frame.pfrac);
 503
 504         // pitch prefilter update
 505         for (i = 0; i < 4; i++)
 506             q->pitch_gain[i] = 0.5 * FFMIN(q->pitch_gain[i], 1.0);
 507
 508         v_pre_filtered       = do_pitchfilter(q->pitch_pre_filter_mem,
 509                                               v_synthesis_filtered,
 510                                               q->pitch_gain, q->pitch_lag,
 511                                               q->frame.pfrac);
 512
 513         apply_gain_ctrl(cdn_vector, v_synthesis_filtered, v_pre_filtered);
 514     } else {
 515         memcpy(q->pitch_synthesis_filter_mem,
 516                cdn_vector + 17, 143 * sizeof(float));
 517         memcpy(q->pitch_pre_filter_mem, cdn_vector + 17, 143 * sizeof(float));
 518         memset(q->pitch_gain, 0, sizeof(q->pitch_gain));
 519         memset(q->pitch_lag,  0, sizeof(q->pitch_lag));
 520     }
 521 }
 522
 523 /**
 524  * Reconstruct LPC coefficients from the line spectral pair frequencies
 525  * and perform bandwidth expansion.
 526  *
 527  * @param lspf line spectral pair frequencies
 528  * @param lpc linear predictive coding coefficients
 529  *
 530  * @note: bandwidth_expansion_coeff could be precalculated into a table
 531  *        but it seems to be slower on x86
 532  *
 533  * TIA/EIA/IS-733 2.4.3.3.5
 534  */
 535 static void lspf2lpc(const float *lspf, float *lpc)
 536 {
 537     double lsp[10];
 538     double bandwidth_expansion_coeff = QCELP_BANDWIDTH_EXPANSION_COEFF;
 539     int i;
 540
 541     for (i = 0; i < 10; i++)
 542         lsp[i] = cos(M_PI * lspf[i]);
 543
 544     ff_acelp_lspd2lpc(lsp, lpc, 5);
 545
 546     for (i = 0; i < 10; i++) {
 547         lpc[i]                    *= bandwidth_expansion_coeff;
 548         bandwidth_expansion_coeff *= QCELP_BANDWIDTH_EXPANSION_COEFF;
 549     }
 550 }
 551
 552 /**
 553  * Interpolate LSP frequencies and compute LPC coefficients
 554  * for a given bitrate & pitch subframe.
 555  *
 556  * TIA/EIA/IS-733 2.4.3.3.4, 2.4.8.7.2
 557  *
 558  * @param q the context
 559  * @param curr_lspf LSP frequencies vector of the current frame
 560  * @param lpc float vector for the resulting LPC
 561  * @param subframe_num frame number in decoded stream
 562  */
 563 static void interpolate_lpc(QCELPContext *q, const float *curr_lspf,
 564                             float *lpc, const int subframe_num)
 565 {
 566     float interpolated_lspf[10];
 567     float weight;
 568
 569     if (q->bitrate >= RATE_QUARTER)
 570         weight = 0.25 * (subframe_num + 1);
 571     else if (q->bitrate == RATE_OCTAVE && !subframe_num)
 572         weight = 0.625;
 573     else
 574         weight = 1.0;
 575
 576     if (weight != 1.0) {
 577         ff_weighted_vector_sumf(interpolated_lspf, curr_lspf, q->prev_lspf,
 578                                 weight, 1.0 - weight, 10);
 579         lspf2lpc(interpolated_lspf, lpc);
 580     } else if (q->bitrate >= RATE_QUARTER ||
 581                (q->bitrate == I_F_Q && !subframe_num))
 582         lspf2lpc(curr_lspf, lpc);
 583     else if (q->bitrate == SILENCE && !subframe_num)
 584         lspf2lpc(q->prev_lspf, lpc);
 585 }
 586
 587 static qcelp_packet_rate buf_size2bitrate(const int buf_size)
 588 {
 589     switch (buf_size) {
 590     case 35: return RATE_FULL;
 591     case 17: return RATE_HALF;
 592     case  8: return RATE_QUARTER;
 593     case  4: return RATE_OCTAVE;
 594     case  1: return SILENCE;
 595     }
 596
 597     return I_F_Q;
 598 }
 599
 600 /**
 601  * Determine the bitrate from the frame size and/or the first byte of the frame.
 602  *
 603  * @param avctx the AV codec context
 604  * @param buf_size length of the buffer
 605  * @param buf the buffer
 606  *
 607  * @return the bitrate on success,
 608  *         I_F_Q  if the bitrate cannot be satisfactorily determined
 609  *
 610  * TIA/EIA/IS-733 2.4.8.7.1
 611  */
 612 static qcelp_packet_rate determine_bitrate(AVCodecContext *avctx,
 613                                            const int buf_size,
 614                                            const uint8_t **buf)
 615 {
 616     qcelp_packet_rate bitrate;
 617
 618     if ((bitrate = buf_size2bitrate(buf_size)) >= 0) {
 619         if (bitrate > **buf) {
 620             QCELPContext *q = avctx->priv_data;
 621             if (!q->warned_buf_mismatch_bitrate) {
 622             av_log(avctx, AV_LOG_WARNING,
 623                    "Claimed bitrate and buffer size mismatch.\n");
 624                 q->warned_buf_mismatch_bitrate = 1;
 625             }
 626             bitrate = **buf;
 627         } else if (bitrate < **buf) {
 628             av_log(avctx, AV_LOG_ERROR,
 629                    "Buffer is too small for the claimed bitrate.\n");
 630             return I_F_Q;
 631         }
 632         (*buf)++;
 633     } else if ((bitrate = buf_size2bitrate(buf_size + 1)) >= 0) {
 634         av_log(avctx, AV_LOG_WARNING,
 635                "Bitrate byte missing, guessing bitrate from packet size.\n");
 636     } else
 637         return I_F_Q;
 638
 639     if (bitrate == SILENCE) {
 640         // FIXME: Remove this warning when tested with samples.
 641         avpriv_request_sample(avctx, "Blank frame handling");
 642     }
 643     return bitrate;
 644 }
 645
 646 static void warn_insufficient_frame_quality(AVCodecContext *avctx,
 647                                             const char *message)
 648 {
 649     av_log(avctx, AV_LOG_WARNING, "Frame #%"PRId64", IFQ: %s\n",
 650            avctx->frame_num, message);
 651 }
 652
 653 static void postfilter(QCELPContext *q, float *samples, float *lpc)
 654 {
 655     static const float pow_0_775[10] = {
 656         0.775000, 0.600625, 0.465484, 0.360750, 0.279582,
 657         0.216676, 0.167924, 0.130141, 0.100859, 0.078166
 658     }, pow_0_625[10] = {
 659         0.625000, 0.390625, 0.244141, 0.152588, 0.095367,
 660         0.059605, 0.037253, 0.023283, 0.014552, 0.009095
 661     };
 662     float lpc_s[10], lpc_p[10], pole_out[170], zero_out[160];
 663     int n;
 664
 665     for (n = 0; n < 10; n++) {
 666         lpc_s[n] = lpc[n] * pow_0_625[n];
 667         lpc_p[n] = lpc[n] * pow_0_775[n];
 668     }
 669
 670     ff_celp_lp_zero_synthesis_filterf(zero_out, lpc_s,
 671                                       q->formant_mem + 10, 160, 10);
 672     memcpy(pole_out, q->postfilter_synth_mem, sizeof(float) * 10);
 673     ff_celp_lp_synthesis_filterf(pole_out + 10, lpc_p, zero_out, 160, 10);
 674     memcpy(q->postfilter_synth_mem, pole_out + 160, sizeof(float) * 10);
 675
 676     ff_tilt_compensation(&q->postfilter_tilt_mem, 0.3, pole_out + 10, 160);
 677
 678     ff_adaptive_gain_control(samples, pole_out + 10,
 679                              avpriv_scalarproduct_float_c(q->formant_mem + 10,
 680                                                           q->formant_mem + 10,
 681                                                           160),
 682                              160, 0.9375, &q->postfilter_agc_mem);
 683 }
 684
 685 static int qcelp_decode_frame(AVCodecContext *avctx, AVFrame *frame,
 686                               int *got_frame_ptr, AVPacket *avpkt)
 687 {
 688     const uint8_t *buf = avpkt->data;
 689     int buf_size       = avpkt->size;
 690     QCELPContext *q    = avctx->priv_data;
 691     float *outbuffer;
 692     int   i, ret;
 693     float quantized_lspf[10], lpc[10];
 694     float gain[16];
 695     float *formant_mem;
 696
 697     /* get output buffer */
 698     frame->nb_samples = 160;
 699     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
 700         return ret;
 701     outbuffer = (float *)frame->data[0];
 702
 703     if ((q->bitrate = determine_bitrate(avctx, buf_size, &buf)) == I_F_Q) {
 704         warn_insufficient_frame_quality(avctx, "Bitrate cannot be determined.");
 705         goto erasure;
 706     }
 707
 708     if (q->bitrate == RATE_OCTAVE &&
 709         (q->first16bits = AV_RB16(buf)) == 0xFFFF) {
 710         warn_insufficient_frame_quality(avctx, "Bitrate is 1/8 and first 16 bits are on.");
 711         goto erasure;
 712     }
 713
 714     if (q->bitrate > SILENCE) {
 715         const QCELPBitmap *bitmaps     = qcelp_unpacking_bitmaps_per_rate[q->bitrate];
 716         const QCELPBitmap *bitmaps_end = qcelp_unpacking_bitmaps_per_rate[q->bitrate] +
 717                                          qcelp_unpacking_bitmaps_lengths[q->bitrate];
 718         uint8_t *unpacked_data         = (uint8_t *)&q->frame;
 719
 720         if ((ret = init_get_bits8(&q->gb, buf, buf_size)) < 0)
 721             return ret;
 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,
 774                                      outbuffer + i * 40, 40, 10);
 775         formant_mem += 40;
 776     }
 777
 778     // postfilter, as per TIA/EIA/IS-733 2.4.8.6
 779     postfilter(q, outbuffer, lpc);
 780
 781     memcpy(q->formant_mem, q->formant_mem + 160, 10 * sizeof(float));
 782
 783     memcpy(q->prev_lspf, quantized_lspf, sizeof(q->prev_lspf));
 784     q->prev_bitrate  = q->bitrate;
 785
 786     *got_frame_ptr = 1;
 787
 788     return buf_size;
 789 }
 790
 791 const FFCodec ff_qcelp_decoder = {
 792     .p.name         = "qcelp",
 793     CODEC_LONG_NAME("QCELP / PureVoice"),
 794     .p.type         = AVMEDIA_TYPE_AUDIO,
 795     .p.id           = AV_CODEC_ID_QCELP,
 796     .init           = qcelp_decode_init,
 797     FF_CODEC_DECODE_CB(qcelp_decode_frame),
 798     .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
 799     .priv_data_size = sizeof(QCELPContext),
 800 };