qcelpdec.c
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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 
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_filters.h"
41 #include "acelp_vectors.h"
42 #include "lsp.h"
43 
44 #undef NDEBUG
45 #include <assert.h>
46 
47 typedef enum {
48  I_F_Q = -1,
55 
56 typedef struct {
62  uint8_t erasure_count;
63  uint8_t octave_count;
64  float prev_lspf[10];
65  float predictor_lspf[10];
66  float pitch_synthesis_filter_mem[303];
67  float pitch_pre_filter_mem[303];
68  float rnd_fir_filter_mem[180];
69  float formant_mem[170];
71  int prev_g1[2];
73  float pitch_gain[4];
74  uint8_t pitch_lag[4];
75  uint16_t first16bits;
77 
78  /* postfilter */
79  float postfilter_synth_mem[10];
82 } QCELPContext;
83 
90 {
91  QCELPContext *q = avctx->priv_data;
92  int i;
93 
95 
96  for (i = 0; i < 10; i++)
97  q->prev_lspf[i] = (i + 1) / 11.;
98 
100  avctx->coded_frame = &q->avframe;
101 
102  return 0;
103 }
104 
116 static int decode_lspf(QCELPContext *q, float *lspf)
117 {
118  int i;
119  float tmp_lspf, smooth, erasure_coeff;
120  const float *predictors;
121 
122  if (q->bitrate == RATE_OCTAVE || q->bitrate == I_F_Q) {
123  predictors = q->prev_bitrate != RATE_OCTAVE &&
124  q->prev_bitrate != I_F_Q ? q->prev_lspf
125  : q->predictor_lspf;
126 
127  if (q->bitrate == RATE_OCTAVE) {
128  q->octave_count++;
129 
130  for (i = 0; i < 10; i++) {
131  q->predictor_lspf[i] =
132  lspf[i] = (q->frame.lspv[i] ? QCELP_LSP_SPREAD_FACTOR
134  predictors[i] * QCELP_LSP_OCTAVE_PREDICTOR +
135  (i + 1) * ((1 - QCELP_LSP_OCTAVE_PREDICTOR) / 11);
136  }
137  smooth = q->octave_count < 10 ? .875 : 0.1;
138  } else {
139  erasure_coeff = QCELP_LSP_OCTAVE_PREDICTOR;
140 
141  assert(q->bitrate == I_F_Q);
142 
143  if (q->erasure_count > 1)
144  erasure_coeff *= q->erasure_count < 4 ? 0.9 : 0.7;
145 
146  for (i = 0; i < 10; i++) {
147  q->predictor_lspf[i] =
148  lspf[i] = (i + 1) * (1 - erasure_coeff) / 11 +
149  erasure_coeff * predictors[i];
150  }
151  smooth = 0.125;
152  }
153 
154  // Check the stability of the LSP frequencies.
155  lspf[0] = FFMAX(lspf[0], QCELP_LSP_SPREAD_FACTOR);
156  for (i = 1; i < 10; i++)
157  lspf[i] = FFMAX(lspf[i], lspf[i - 1] + QCELP_LSP_SPREAD_FACTOR);
158 
159  lspf[9] = FFMIN(lspf[9], 1.0 - QCELP_LSP_SPREAD_FACTOR);
160  for (i = 9; i > 0; i--)
161  lspf[i - 1] = FFMIN(lspf[i - 1], lspf[i] - QCELP_LSP_SPREAD_FACTOR);
162 
163  // Low-pass filter the LSP frequencies.
164  ff_weighted_vector_sumf(lspf, lspf, q->prev_lspf, smooth, 1.0 - smooth, 10);
165  } else {
166  q->octave_count = 0;
167 
168  tmp_lspf = 0.;
169  for (i = 0; i < 5; i++) {
170  lspf[2 * i + 0] = tmp_lspf += qcelp_lspvq[i][q->frame.lspv[i]][0] * 0.0001;
171  lspf[2 * i + 1] = tmp_lspf += qcelp_lspvq[i][q->frame.lspv[i]][1] * 0.0001;
172  }
173 
174  // Check for badly received packets.
175  if (q->bitrate == RATE_QUARTER) {
176  if (lspf[9] <= .70 || lspf[9] >= .97)
177  return -1;
178  for (i = 3; i < 10; i++)
179  if (fabs(lspf[i] - lspf[i - 2]) < .08)
180  return -1;
181  } else {
182  if (lspf[9] <= .66 || lspf[9] >= .985)
183  return -1;
184  for (i = 4; i < 10; i++)
185  if (fabs(lspf[i] - lspf[i - 4]) < .0931)
186  return -1;
187  }
188  }
189  return 0;
190 }
191 
200 static void decode_gain_and_index(QCELPContext *q, float *gain)
201 {
202  int i, subframes_count, g1[16];
203  float slope;
204 
205  if (q->bitrate >= RATE_QUARTER) {
206  switch (q->bitrate) {
207  case RATE_FULL: subframes_count = 16; break;
208  case RATE_HALF: subframes_count = 4; break;
209  default: subframes_count = 5;
210  }
211  for (i = 0; i < subframes_count; i++) {
212  g1[i] = 4 * q->frame.cbgain[i];
213  if (q->bitrate == RATE_FULL && !((i + 1) & 3)) {
214  g1[i] += av_clip((g1[i - 1] + g1[i - 2] + g1[i - 3]) / 3 - 6, 0, 32);
215  }
216 
217  gain[i] = qcelp_g12ga[g1[i]];
218 
219  if (q->frame.cbsign[i]) {
220  gain[i] = -gain[i];
221  q->frame.cindex[i] = (q->frame.cindex[i] - 89) & 127;
222  }
223  }
224 
225  q->prev_g1[0] = g1[i - 2];
226  q->prev_g1[1] = g1[i - 1];
227  q->last_codebook_gain = qcelp_g12ga[g1[i - 1]];
228 
229  if (q->bitrate == RATE_QUARTER) {
230  // Provide smoothing of the unvoiced excitation energy.
231  gain[7] = gain[4];
232  gain[6] = 0.4 * gain[3] + 0.6 * gain[4];
233  gain[5] = gain[3];
234  gain[4] = 0.8 * gain[2] + 0.2 * gain[3];
235  gain[3] = 0.2 * gain[1] + 0.8 * gain[2];
236  gain[2] = gain[1];
237  gain[1] = 0.6 * gain[0] + 0.4 * gain[1];
238  }
239  } else if (q->bitrate != SILENCE) {
240  if (q->bitrate == RATE_OCTAVE) {
241  g1[0] = 2 * q->frame.cbgain[0] +
242  av_clip((q->prev_g1[0] + q->prev_g1[1]) / 2 - 5, 0, 54);
243  subframes_count = 8;
244  } else {
245  assert(q->bitrate == I_F_Q);
246 
247  g1[0] = q->prev_g1[1];
248  switch (q->erasure_count) {
249  case 1 : break;
250  case 2 : g1[0] -= 1; break;
251  case 3 : g1[0] -= 2; break;
252  default: g1[0] -= 6;
253  }
254  if (g1[0] < 0)
255  g1[0] = 0;
256  subframes_count = 4;
257  }
258  // This interpolation is done to produce smoother background noise.
259  slope = 0.5 * (qcelp_g12ga[g1[0]] - q->last_codebook_gain) / subframes_count;
260  for (i = 1; i <= subframes_count; i++)
261  gain[i - 1] = q->last_codebook_gain + slope * i;
262 
263  q->last_codebook_gain = gain[i - 2];
264  q->prev_g1[0] = q->prev_g1[1];
265  q->prev_g1[1] = g1[0];
266  }
267 }
268 
278 static int codebook_sanity_check_for_rate_quarter(const uint8_t *cbgain)
279 {
280  int i, diff, prev_diff = 0;
281 
282  for (i = 1; i < 5; i++) {
283  diff = cbgain[i] - cbgain[i-1];
284  if (FFABS(diff) > 10)
285  return -1;
286  else if (FFABS(diff - prev_diff) > 12)
287  return -1;
288  prev_diff = diff;
289  }
290  return 0;
291 }
292 
314 static void compute_svector(QCELPContext *q, const float *gain,
315  float *cdn_vector)
316 {
317  int i, j, k;
318  uint16_t cbseed, cindex;
319  float *rnd, tmp_gain, fir_filter_value;
320 
321  switch (q->bitrate) {
322  case RATE_FULL:
323  for (i = 0; i < 16; i++) {
324  tmp_gain = gain[i] * QCELP_RATE_FULL_CODEBOOK_RATIO;
325  cindex = -q->frame.cindex[i];
326  for (j = 0; j < 10; j++)
327  *cdn_vector++ = tmp_gain * qcelp_rate_full_codebook[cindex++ & 127];
328  }
329  break;
330  case RATE_HALF:
331  for (i = 0; i < 4; i++) {
332  tmp_gain = gain[i] * QCELP_RATE_HALF_CODEBOOK_RATIO;
333  cindex = -q->frame.cindex[i];
334  for (j = 0; j < 40; j++)
335  *cdn_vector++ = tmp_gain * qcelp_rate_half_codebook[cindex++ & 127];
336  }
337  break;
338  case RATE_QUARTER:
339  cbseed = (0x0003 & q->frame.lspv[4]) << 14 |
340  (0x003F & q->frame.lspv[3]) << 8 |
341  (0x0060 & q->frame.lspv[2]) << 1 |
342  (0x0007 & q->frame.lspv[1]) << 3 |
343  (0x0038 & q->frame.lspv[0]) >> 3;
344  rnd = q->rnd_fir_filter_mem + 20;
345  for (i = 0; i < 8; i++) {
346  tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
347  for (k = 0; k < 20; k++) {
348  cbseed = 521 * cbseed + 259;
349  *rnd = (int16_t) cbseed;
350 
351  // FIR filter
352  fir_filter_value = 0.0;
353  for (j = 0; j < 10; j++)
354  fir_filter_value += qcelp_rnd_fir_coefs[j] *
355  (rnd[-j] + rnd[-20+j]);
356 
357  fir_filter_value += qcelp_rnd_fir_coefs[10] * rnd[-10];
358  *cdn_vector++ = tmp_gain * fir_filter_value;
359  rnd++;
360  }
361  }
362  memcpy(q->rnd_fir_filter_mem, q->rnd_fir_filter_mem + 160,
363  20 * sizeof(float));
364  break;
365  case RATE_OCTAVE:
366  cbseed = q->first16bits;
367  for (i = 0; i < 8; i++) {
368  tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
369  for (j = 0; j < 20; j++) {
370  cbseed = 521 * cbseed + 259;
371  *cdn_vector++ = tmp_gain * (int16_t) cbseed;
372  }
373  }
374  break;
375  case I_F_Q:
376  cbseed = -44; // random codebook index
377  for (i = 0; i < 4; i++) {
378  tmp_gain = gain[i] * QCELP_RATE_FULL_CODEBOOK_RATIO;
379  for (j = 0; j < 40; j++)
380  *cdn_vector++ = tmp_gain * qcelp_rate_full_codebook[cbseed++ & 127];
381  }
382  break;
383  case SILENCE:
384  memset(cdn_vector, 0, 160 * sizeof(float));
385  break;
386  }
387 }
388 
398 static void apply_gain_ctrl(float *v_out, const float *v_ref, const float *v_in)
399 {
400  int i;
401 
402  for (i = 0; i < 160; i += 40)
403  ff_scale_vector_to_given_sum_of_squares(v_out + i, v_in + i,
404  ff_dot_productf(v_ref + i,
405  v_ref + i, 40),
406  40);
407 }
408 
426 static const float *do_pitchfilter(float memory[303], const float v_in[160],
427  const float gain[4], const uint8_t *lag,
428  const uint8_t pfrac[4])
429 {
430  int i, j;
431  float *v_lag, *v_out;
432  const float *v_len;
433 
434  v_out = memory + 143; // Output vector starts at memory[143].
435 
436  for (i = 0; i < 4; i++) {
437  if (gain[i]) {
438  v_lag = memory + 143 + 40 * i - lag[i];
439  for (v_len = v_in + 40; v_in < v_len; v_in++) {
440  if (pfrac[i]) { // If it is a fractional lag...
441  for (j = 0, *v_out = 0.; j < 4; j++)
442  *v_out += qcelp_hammsinc_table[j] * (v_lag[j - 4] + v_lag[3 - j]);
443  } else
444  *v_out = *v_lag;
445 
446  *v_out = *v_in + gain[i] * *v_out;
447 
448  v_lag++;
449  v_out++;
450  }
451  } else {
452  memcpy(v_out, v_in, 40 * sizeof(float));
453  v_in += 40;
454  v_out += 40;
455  }
456  }
457 
458  memmove(memory, memory + 160, 143 * sizeof(float));
459  return memory + 143;
460 }
461 
469 static void apply_pitch_filters(QCELPContext *q, float *cdn_vector)
470 {
471  int i;
472  const float *v_synthesis_filtered, *v_pre_filtered;
473 
474  if (q->bitrate >= RATE_HALF || q->bitrate == SILENCE ||
475  (q->bitrate == I_F_Q && (q->prev_bitrate >= RATE_HALF))) {
476 
477  if (q->bitrate >= RATE_HALF) {
478  // Compute gain & lag for the whole frame.
479  for (i = 0; i < 4; i++) {
480  q->pitch_gain[i] = q->frame.plag[i] ? (q->frame.pgain[i] + 1) * 0.25 : 0.0;
481 
482  q->pitch_lag[i] = q->frame.plag[i] + 16;
483  }
484  } else {
485  float max_pitch_gain;
486 
487  if (q->bitrate == I_F_Q) {
488  if (q->erasure_count < 3)
489  max_pitch_gain = 0.9 - 0.3 * (q->erasure_count - 1);
490  else
491  max_pitch_gain = 0.0;
492  } else {
493  assert(q->bitrate == SILENCE);
494  max_pitch_gain = 1.0;
495  }
496  for (i = 0; i < 4; i++)
497  q->pitch_gain[i] = FFMIN(q->pitch_gain[i], max_pitch_gain);
498 
499  memset(q->frame.pfrac, 0, sizeof(q->frame.pfrac));
500  }
501 
502  // pitch synthesis filter
503  v_synthesis_filtered = do_pitchfilter(q->pitch_synthesis_filter_mem,
504  cdn_vector, q->pitch_gain,
505  q->pitch_lag, q->frame.pfrac);
506 
507  // pitch prefilter update
508  for (i = 0; i < 4; i++)
509  q->pitch_gain[i] = 0.5 * FFMIN(q->pitch_gain[i], 1.0);
510 
511  v_pre_filtered = do_pitchfilter(q->pitch_pre_filter_mem,
512  v_synthesis_filtered,
513  q->pitch_gain, q->pitch_lag,
514  q->frame.pfrac);
515 
516  apply_gain_ctrl(cdn_vector, v_synthesis_filtered, v_pre_filtered);
517  } else {
518  memcpy(q->pitch_synthesis_filter_mem, cdn_vector + 17, 143 * sizeof(float));
519  memcpy(q->pitch_pre_filter_mem, cdn_vector + 17, 143 * sizeof(float));
520  memset(q->pitch_gain, 0, sizeof(q->pitch_gain));
521  memset(q->pitch_lag, 0, sizeof(q->pitch_lag));
522  }
523 }
524 
537 static void lspf2lpc(const float *lspf, float *lpc)
538 {
539  double lsp[10];
540  double bandwidth_expansion_coeff = QCELP_BANDWIDTH_EXPANSION_COEFF;
541  int i;
542 
543  for (i = 0; i < 10; i++)
544  lsp[i] = cos(M_PI * lspf[i]);
545 
546  ff_acelp_lspd2lpc(lsp, lpc, 5);
547 
548  for (i = 0; i < 10; i++) {
549  lpc[i] *= bandwidth_expansion_coeff;
550  bandwidth_expansion_coeff *= QCELP_BANDWIDTH_EXPANSION_COEFF;
551  }
552 }
553 
565 static void interpolate_lpc(QCELPContext *q, const float *curr_lspf,
566  float *lpc, const int subframe_num)
567 {
568  float interpolated_lspf[10];
569  float weight;
570 
571  if (q->bitrate >= RATE_QUARTER)
572  weight = 0.25 * (subframe_num + 1);
573  else if (q->bitrate == RATE_OCTAVE && !subframe_num)
574  weight = 0.625;
575  else
576  weight = 1.0;
577 
578  if (weight != 1.0) {
579  ff_weighted_vector_sumf(interpolated_lspf, curr_lspf, q->prev_lspf,
580  weight, 1.0 - weight, 10);
581  lspf2lpc(interpolated_lspf, lpc);
582  } else if (q->bitrate >= RATE_QUARTER ||
583  (q->bitrate == I_F_Q && !subframe_num))
584  lspf2lpc(curr_lspf, lpc);
585  else if (q->bitrate == SILENCE && !subframe_num)
586  lspf2lpc(q->prev_lspf, lpc);
587 }
588 
589 static qcelp_packet_rate buf_size2bitrate(const int buf_size)
590 {
591  switch (buf_size) {
592  case 35: return RATE_FULL;
593  case 17: return RATE_HALF;
594  case 8: return RATE_QUARTER;
595  case 4: return RATE_OCTAVE;
596  case 1: return SILENCE;
597  }
598 
599  return I_F_Q;
600 }
601 
615  const int buf_size,
616  const uint8_t **buf)
617 {
618  qcelp_packet_rate bitrate;
619 
620  if ((bitrate = buf_size2bitrate(buf_size)) >= 0) {
621  if (bitrate > **buf) {
622  QCELPContext *q = avctx->priv_data;
623  if (!q->warned_buf_mismatch_bitrate) {
624  av_log(avctx, AV_LOG_WARNING,
625  "Claimed bitrate and buffer size mismatch.\n");
627  }
628  bitrate = **buf;
629  } else if (bitrate < **buf) {
630  av_log(avctx, AV_LOG_ERROR,
631  "Buffer is too small for the claimed bitrate.\n");
632  return I_F_Q;
633  }
634  (*buf)++;
635  } else if ((bitrate = buf_size2bitrate(buf_size + 1)) >= 0) {
636  av_log(avctx, AV_LOG_WARNING,
637  "Bitrate byte is missing, guessing the bitrate from packet size.\n");
638  } else
639  return I_F_Q;
640 
641  if (bitrate == SILENCE) {
642  //FIXME: Remove experimental warning when tested with samples.
643  av_log_ask_for_sample(avctx, "'Blank frame handling is experimental.");
644  }
645  return bitrate;
646 }
647 
649  const char *message)
650 {
651  av_log(avctx, AV_LOG_WARNING, "Frame #%d, IFQ: %s\n",
652  avctx->frame_number, message);
653 }
654 
655 static void postfilter(QCELPContext *q, float *samples, float *lpc)
656 {
657  static const float pow_0_775[10] = {
658  0.775000, 0.600625, 0.465484, 0.360750, 0.279582,
659  0.216676, 0.167924, 0.130141, 0.100859, 0.078166
660  }, pow_0_625[10] = {
661  0.625000, 0.390625, 0.244141, 0.152588, 0.095367,
662  0.059605, 0.037253, 0.023283, 0.014552, 0.009095
663  };
664  float lpc_s[10], lpc_p[10], pole_out[170], zero_out[160];
665  int n;
666 
667  for (n = 0; n < 10; n++) {
668  lpc_s[n] = lpc[n] * pow_0_625[n];
669  lpc_p[n] = lpc[n] * pow_0_775[n];
670  }
671 
672  ff_celp_lp_zero_synthesis_filterf(zero_out, lpc_s,
673  q->formant_mem + 10, 160, 10);
674  memcpy(pole_out, q->postfilter_synth_mem, sizeof(float) * 10);
675  ff_celp_lp_synthesis_filterf(pole_out + 10, lpc_p, zero_out, 160, 10);
676  memcpy(q->postfilter_synth_mem, pole_out + 160, sizeof(float) * 10);
677 
678  ff_tilt_compensation(&q->postfilter_tilt_mem, 0.3, pole_out + 10, 160);
679 
680  ff_adaptive_gain_control(samples, pole_out + 10,
682  q->formant_mem + 10, 160),
683  160, 0.9375, &q->postfilter_agc_mem);
684 }
685 
686 static int qcelp_decode_frame(AVCodecContext *avctx, void *data,
687  int *got_frame_ptr, AVPacket *avpkt)
688 {
689  const uint8_t *buf = avpkt->data;
690  int buf_size = avpkt->size;
691  QCELPContext *q = avctx->priv_data;
692  float *outbuffer;
693  int i, ret;
694  float quantized_lspf[10], lpc[10];
695  float gain[16];
696  float *formant_mem;
697 
698  /* get output buffer */
699  q->avframe.nb_samples = 160;
700  if ((ret = ff_get_buffer(avctx, &q->avframe)) < 0) {
701  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
702  return ret;
703  }
704  outbuffer = (float *)q->avframe.data[0];
705 
706  if ((q->bitrate = determine_bitrate(avctx, buf_size, &buf)) == I_F_Q) {
707  warn_insufficient_frame_quality(avctx, "bitrate cannot be determined.");
708  goto erasure;
709  }
710 
711  if (q->bitrate == RATE_OCTAVE &&
712  (q->first16bits = AV_RB16(buf)) == 0xFFFF) {
713  warn_insufficient_frame_quality(avctx, "Bitrate is 1/8 and first 16 bits are on.");
714  goto erasure;
715  }
716 
717  if (q->bitrate > SILENCE) {
719  const QCELPBitmap *bitmaps_end = qcelp_unpacking_bitmaps_per_rate[q->bitrate] +
721  uint8_t *unpacked_data = (uint8_t *)&q->frame;
722 
723  init_get_bits(&q->gb, buf, 8 * buf_size);
724 
725  memset(&q->frame, 0, sizeof(QCELPFrame));
726 
727  for (; bitmaps < bitmaps_end; bitmaps++)
728  unpacked_data[bitmaps->index] |= get_bits(&q->gb, bitmaps->bitlen) << bitmaps->bitpos;
729 
730  // Check for erasures/blanks on rates 1, 1/4 and 1/8.
731  if (q->frame.reserved) {
732  warn_insufficient_frame_quality(avctx, "Wrong data in reserved frame area.");
733  goto erasure;
734  }
735  if (q->bitrate == RATE_QUARTER &&
737  warn_insufficient_frame_quality(avctx, "Codebook gain sanity check failed.");
738  goto erasure;
739  }
740 
741  if (q->bitrate >= RATE_HALF) {
742  for (i = 0; i < 4; i++) {
743  if (q->frame.pfrac[i] && q->frame.plag[i] >= 124) {
744  warn_insufficient_frame_quality(avctx, "Cannot initialize pitch filter.");
745  goto erasure;
746  }
747  }
748  }
749  }
750 
751  decode_gain_and_index(q, gain);
752  compute_svector(q, gain, outbuffer);
753 
754  if (decode_lspf(q, quantized_lspf) < 0) {
755  warn_insufficient_frame_quality(avctx, "Badly received packets in frame.");
756  goto erasure;
757  }
758 
759  apply_pitch_filters(q, outbuffer);
760 
761  if (q->bitrate == I_F_Q) {
762 erasure:
763  q->bitrate = I_F_Q;
764  q->erasure_count++;
765  decode_gain_and_index(q, gain);
766  compute_svector(q, gain, outbuffer);
767  decode_lspf(q, quantized_lspf);
768  apply_pitch_filters(q, outbuffer);
769  } else
770  q->erasure_count = 0;
771 
772  formant_mem = q->formant_mem + 10;
773  for (i = 0; i < 4; i++) {
774  interpolate_lpc(q, quantized_lspf, lpc, i);
775  ff_celp_lp_synthesis_filterf(formant_mem, lpc, outbuffer + i * 40, 40, 10);
776  formant_mem += 40;
777  }
778 
779  // postfilter, as per TIA/EIA/IS-733 2.4.8.6
780  postfilter(q, outbuffer, lpc);
781 
782  memcpy(q->formant_mem, q->formant_mem + 160, 10 * sizeof(float));
783 
784  memcpy(q->prev_lspf, quantized_lspf, sizeof(q->prev_lspf));
785  q->prev_bitrate = q->bitrate;
786 
787  *got_frame_ptr = 1;
788  *(AVFrame *)data = q->avframe;
789 
790  return buf_size;
791 }
792 
794  .name = "qcelp",
795  .type = AVMEDIA_TYPE_AUDIO,
796  .id = CODEC_ID_QCELP,
797  .init = qcelp_decode_init,
798  .decode = qcelp_decode_frame,
799  .capabilities = CODEC_CAP_DR1,
800  .priv_data_size = sizeof(QCELPContext),
801  .long_name = NULL_IF_CONFIG_SMALL("QCELP / PureVoice"),
802 };