3 * Copyright (c) 2007 Reynaldo H. Verdejo Pinochet
5 * This file is part of Libav.
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.
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.
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
25 * @author Reynaldo H. Verdejo Pinochet
26 * @remark Libav merging spearheaded by Kenan Gillet
27 * @remark Development mentored by Benjamin Larson
36 #include "qcelpdata.h"
38 #include "celp_math.h"
39 #include "celp_filters.h"
40 #include "acelp_filters.h"
41 #include "acelp_vectors.h"
49 I_F_Q = -1, /**< insufficient frame quality */
61 qcelp_packet_rate bitrate;
62 QCELPFrame frame; /**< unpacked data frame */
64 uint8_t erasure_count;
65 uint8_t octave_count; /**< count the consecutive RATE_OCTAVE frames */
67 float predictor_lspf[10];/**< LSP predictor for RATE_OCTAVE and I_F_Q */
68 float pitch_synthesis_filter_mem[303];
69 float pitch_pre_filter_mem[303];
70 float rnd_fir_filter_mem[180];
71 float formant_mem[170];
72 float last_codebook_gain;
78 uint8_t warned_buf_mismatch_bitrate;
81 float postfilter_synth_mem[10];
82 float postfilter_agc_mem;
83 float postfilter_tilt_mem;
87 * Initialize the speech codec according to the specification.
89 * TIA/EIA/IS-733 2.4.9
91 static av_cold int qcelp_decode_init(AVCodecContext *avctx)
93 QCELPContext *q = avctx->priv_data;
96 avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
99 q->prev_lspf[i] = (i+1)/11.;
101 avcodec_get_frame_defaults(&q->avframe);
102 avctx->coded_frame = &q->avframe;
108 * Decode the 10 quantized LSP frequencies from the LSPV/LSP
109 * transmission codes of any bitrate and check for badly received packets.
111 * @param q the context
112 * @param lspf line spectral pair frequencies
114 * @return 0 on success, -1 if the packet is badly received
116 * TIA/EIA/IS-733 2.4.3.2.6.2-2, 2.4.8.7.3
118 static int decode_lspf(QCELPContext *q, float *lspf)
121 float tmp_lspf, smooth, erasure_coeff;
122 const float *predictors;
124 if (q->bitrate == RATE_OCTAVE || q->bitrate == I_F_Q) {
125 predictors = (q->prev_bitrate != RATE_OCTAVE &&
126 q->prev_bitrate != I_F_Q ?
127 q->prev_lspf : q->predictor_lspf);
129 if (q->bitrate == RATE_OCTAVE) {
132 for (i=0; i<10; i++) {
133 q->predictor_lspf[i] =
134 lspf[i] = (q->frame.lspv[i] ? QCELP_LSP_SPREAD_FACTOR
135 : -QCELP_LSP_SPREAD_FACTOR)
136 + predictors[i] * QCELP_LSP_OCTAVE_PREDICTOR
137 + (i + 1) * ((1 - QCELP_LSP_OCTAVE_PREDICTOR)/11);
139 smooth = (q->octave_count < 10 ? .875 : 0.1);
141 erasure_coeff = QCELP_LSP_OCTAVE_PREDICTOR;
143 assert(q->bitrate == I_F_Q);
145 if(q->erasure_count > 1)
146 erasure_coeff *= (q->erasure_count < 4 ? 0.9 : 0.7);
148 for(i = 0; i < 10; i++) {
149 q->predictor_lspf[i] =
150 lspf[i] = (i + 1) * ( 1 - erasure_coeff)/11
151 + erasure_coeff * predictors[i];
156 // Check the stability of the LSP frequencies.
157 lspf[0] = FFMAX(lspf[0], QCELP_LSP_SPREAD_FACTOR);
159 lspf[i] = FFMAX(lspf[i], (lspf[i-1] + QCELP_LSP_SPREAD_FACTOR));
161 lspf[9] = FFMIN(lspf[9], (1.0 - QCELP_LSP_SPREAD_FACTOR));
163 lspf[i-1] = FFMIN(lspf[i-1], (lspf[i] - QCELP_LSP_SPREAD_FACTOR));
165 // Low-pass filter the LSP frequencies.
166 ff_weighted_vector_sumf(lspf, lspf, q->prev_lspf, smooth, 1.0-smooth, 10);
171 for (i = 0; i < 5; i++) {
172 lspf[2*i+0] = tmp_lspf += qcelp_lspvq[i][q->frame.lspv[i]][0] * 0.0001;
173 lspf[2*i+1] = tmp_lspf += qcelp_lspvq[i][q->frame.lspv[i]][1] * 0.0001;
176 // Check for badly received packets.
177 if (q->bitrate == RATE_QUARTER) {
178 if(lspf[9] <= .70 || lspf[9] >= .97)
181 if(fabs(lspf[i] - lspf[i-2]) < .08)
184 if(lspf[9] <= .66 || lspf[9] >= .985)
187 if (fabs(lspf[i] - lspf[i-4]) < .0931)
195 * Convert codebook transmission codes to GAIN and INDEX.
197 * @param q the context
198 * @param gain array holding the decoded gain
200 * TIA/EIA/IS-733 2.4.6.2
202 static void decode_gain_and_index(QCELPContext *q,
204 int i, subframes_count, g1[16];
207 if (q->bitrate >= RATE_QUARTER) {
208 switch (q->bitrate) {
209 case RATE_FULL: subframes_count = 16; break;
210 case RATE_HALF: subframes_count = 4; break;
211 default: subframes_count = 5;
213 for(i = 0; i < subframes_count; i++) {
214 g1[i] = 4 * q->frame.cbgain[i];
215 if (q->bitrate == RATE_FULL && !((i+1) & 3)) {
216 g1[i] += av_clip((g1[i-1] + g1[i-2] + g1[i-3]) / 3 - 6, 0, 32);
219 gain[i] = qcelp_g12ga[g1[i]];
221 if (q->frame.cbsign[i]) {
223 q->frame.cindex[i] = (q->frame.cindex[i]-89) & 127;
227 q->prev_g1[0] = g1[i-2];
228 q->prev_g1[1] = g1[i-1];
229 q->last_codebook_gain = qcelp_g12ga[g1[i-1]];
231 if (q->bitrate == RATE_QUARTER) {
232 // Provide smoothing of the unvoiced excitation energy.
234 gain[6] = 0.4*gain[3] + 0.6*gain[4];
236 gain[4] = 0.8*gain[2] + 0.2*gain[3];
237 gain[3] = 0.2*gain[1] + 0.8*gain[2];
239 gain[1] = 0.6*gain[0] + 0.4*gain[1];
241 } else if (q->bitrate != SILENCE) {
242 if (q->bitrate == RATE_OCTAVE) {
243 g1[0] = 2 * q->frame.cbgain[0]
244 + av_clip((q->prev_g1[0] + q->prev_g1[1]) / 2 - 5, 0, 54);
247 assert(q->bitrate == I_F_Q);
249 g1[0] = q->prev_g1[1];
250 switch (q->erasure_count) {
252 case 2 : g1[0] -= 1; break;
253 case 3 : g1[0] -= 2; break;
260 // This interpolation is done to produce smoother background noise.
261 slope = 0.5*(qcelp_g12ga[g1[0]] - q->last_codebook_gain) / subframes_count;
262 for(i=1; i<=subframes_count; i++)
263 gain[i-1] = q->last_codebook_gain + slope * i;
265 q->last_codebook_gain = gain[i-2];
266 q->prev_g1[0] = q->prev_g1[1];
267 q->prev_g1[1] = g1[0];
272 * If the received packet is Rate 1/4 a further sanity check is made of the
275 * @param cbgain the unpacked cbgain array
276 * @return -1 if the sanity check fails, 0 otherwise
278 * TIA/EIA/IS-733 2.4.8.7.3
280 static int codebook_sanity_check_for_rate_quarter(const uint8_t *cbgain)
282 int i, diff, prev_diff=0;
285 diff = cbgain[i] - cbgain[i-1];
288 else if(FFABS(diff - prev_diff) > 12)
296 * Compute the scaled codebook vector Cdn From INDEX and GAIN
299 * The specification lacks some information here.
301 * TIA/EIA/IS-733 has an omission on the codebook index determination
302 * formula for RATE_FULL and RATE_HALF frames at section 2.4.8.1.1. It says
303 * you have to subtract the decoded index parameter from the given scaled
304 * codebook vector index 'n' to get the desired circular codebook index, but
305 * it does not mention that you have to clamp 'n' to [0-9] in order to get
306 * RI-compliant results.
308 * The reason for this mistake seems to be the fact they forgot to mention you
309 * have to do these calculations per codebook subframe and adjust given
310 * equation values accordingly.
312 * @param q the context
313 * @param gain array holding the 4 pitch subframe gain values
314 * @param cdn_vector array for the generated scaled codebook vector
316 static void compute_svector(QCELPContext *q, const float *gain,
320 uint16_t cbseed, cindex;
321 float *rnd, tmp_gain, fir_filter_value;
323 switch (q->bitrate) {
325 for (i = 0; i < 16; i++) {
326 tmp_gain = gain[i] * QCELP_RATE_FULL_CODEBOOK_RATIO;
327 cindex = -q->frame.cindex[i];
329 *cdn_vector++ = tmp_gain * qcelp_rate_full_codebook[cindex++ & 127];
333 for (i = 0; i < 4; i++) {
334 tmp_gain = gain[i] * QCELP_RATE_HALF_CODEBOOK_RATIO;
335 cindex = -q->frame.cindex[i];
336 for (j = 0; j < 40; j++)
337 *cdn_vector++ = tmp_gain * qcelp_rate_half_codebook[cindex++ & 127];
341 cbseed = (0x0003 & q->frame.lspv[4])<<14 |
342 (0x003F & q->frame.lspv[3])<< 8 |
343 (0x0060 & q->frame.lspv[2])<< 1 |
344 (0x0007 & q->frame.lspv[1])<< 3 |
345 (0x0038 & q->frame.lspv[0])>> 3 ;
346 rnd = q->rnd_fir_filter_mem + 20;
347 for (i = 0; i < 8; i++) {
348 tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
349 for (k = 0; k < 20; k++) {
350 cbseed = 521 * cbseed + 259;
351 *rnd = (int16_t)cbseed;
354 fir_filter_value = 0.0;
356 fir_filter_value += qcelp_rnd_fir_coefs[j ]
357 * (rnd[-j ] + rnd[-20+j]);
359 fir_filter_value += qcelp_rnd_fir_coefs[10] * rnd[-10];
360 *cdn_vector++ = tmp_gain * fir_filter_value;
364 memcpy(q->rnd_fir_filter_mem, q->rnd_fir_filter_mem + 160, 20 * sizeof(float));
367 cbseed = q->first16bits;
368 for (i = 0; i < 8; i++) {
369 tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
370 for (j = 0; j < 20; j++) {
371 cbseed = 521 * cbseed + 259;
372 *cdn_vector++ = tmp_gain * (int16_t)cbseed;
377 cbseed = -44; // random codebook index
378 for (i = 0; i < 4; i++) {
379 tmp_gain = gain[i] * QCELP_RATE_FULL_CODEBOOK_RATIO;
381 *cdn_vector++ = tmp_gain * qcelp_rate_full_codebook[cbseed++ & 127];
385 memset(cdn_vector, 0, 160 * sizeof(float));
391 * Apply generic gain control.
393 * @param v_out output vector
394 * @param v_in gain-controlled vector
395 * @param v_ref vector to control gain of
397 * TIA/EIA/IS-733 2.4.8.3, 2.4.8.6
399 static void apply_gain_ctrl(float *v_out, const float *v_ref,
404 for (i = 0; i < 160; i += 40)
405 ff_scale_vector_to_given_sum_of_squares(v_out + i, v_in + i,
406 ff_dot_productf(v_ref + i,
412 * Apply filter in pitch-subframe steps.
414 * @param memory buffer for the previous state of the filter
415 * - must be able to contain 303 elements
416 * - the 143 first elements are from the previous state
417 * - the next 160 are for output
418 * @param v_in input filter vector
419 * @param gain per-subframe gain array, each element is between 0.0 and 2.0
420 * @param lag per-subframe lag array, each element is
421 * - between 16 and 143 if its corresponding pfrac is 0,
422 * - between 16 and 139 otherwise
423 * @param pfrac per-subframe boolean array, 1 if the lag is fractional, 0
426 * @return filter output vector
428 static const float *do_pitchfilter(float memory[303], const float v_in[160],
429 const float gain[4], const uint8_t *lag,
430 const uint8_t pfrac[4])
433 float *v_lag, *v_out;
436 v_out = memory + 143; // Output vector starts at memory[143].
438 for (i = 0; i < 4; i++) {
440 v_lag = memory + 143 + 40 * i - lag[i];
441 for (v_len = v_in + 40; v_in < v_len; v_in++) {
442 if (pfrac[i]) { // If it is a fractional lag...
443 for(j=0, *v_out=0.; j<4; j++)
444 *v_out += qcelp_hammsinc_table[j] * (v_lag[j-4] + v_lag[3-j]);
448 *v_out = *v_in + gain[i] * *v_out;
454 memcpy(v_out, v_in, 40 * sizeof(float));
460 memmove(memory, memory + 160, 143 * sizeof(float));
465 * Apply pitch synthesis filter and pitch prefilter to the scaled codebook vector.
466 * TIA/EIA/IS-733 2.4.5.2, 2.4.8.7.2
468 * @param q the context
469 * @param cdn_vector the scaled codebook vector
471 static void apply_pitch_filters(QCELPContext *q, float *cdn_vector)
474 const float *v_synthesis_filtered, *v_pre_filtered;
476 if(q->bitrate >= RATE_HALF ||
477 q->bitrate == SILENCE ||
478 (q->bitrate == I_F_Q && (q->prev_bitrate >= RATE_HALF))) {
480 if(q->bitrate >= RATE_HALF) {
482 // Compute gain & lag for the whole frame.
483 for (i = 0; i < 4; i++) {
484 q->pitch_gain[i] = q->frame.plag[i] ? (q->frame.pgain[i] + 1) * 0.25 : 0.0;
486 q->pitch_lag[i] = q->frame.plag[i] + 16;
489 float max_pitch_gain;
491 if (q->bitrate == I_F_Q) {
492 if (q->erasure_count < 3)
493 max_pitch_gain = 0.9 - 0.3 * (q->erasure_count - 1);
495 max_pitch_gain = 0.0;
497 assert(q->bitrate == SILENCE);
498 max_pitch_gain = 1.0;
501 q->pitch_gain[i] = FFMIN(q->pitch_gain[i], max_pitch_gain);
503 memset(q->frame.pfrac, 0, sizeof(q->frame.pfrac));
506 // pitch synthesis filter
507 v_synthesis_filtered = do_pitchfilter(q->pitch_synthesis_filter_mem,
508 cdn_vector, q->pitch_gain,
509 q->pitch_lag, q->frame.pfrac);
511 // pitch prefilter update
513 q->pitch_gain[i] = 0.5 * FFMIN(q->pitch_gain[i], 1.0);
515 v_pre_filtered = do_pitchfilter(q->pitch_pre_filter_mem,
516 v_synthesis_filtered,
517 q->pitch_gain, q->pitch_lag,
520 apply_gain_ctrl(cdn_vector, v_synthesis_filtered, v_pre_filtered);
522 memcpy(q->pitch_synthesis_filter_mem, cdn_vector + 17,
523 143 * sizeof(float));
524 memcpy(q->pitch_pre_filter_mem, cdn_vector + 17, 143 * sizeof(float));
525 memset(q->pitch_gain, 0, sizeof(q->pitch_gain));
526 memset(q->pitch_lag, 0, sizeof(q->pitch_lag));
531 * Reconstruct LPC coefficients from the line spectral pair frequencies
532 * and perform bandwidth expansion.
534 * @param lspf line spectral pair frequencies
535 * @param lpc linear predictive coding coefficients
537 * @note: bandwidth_expansion_coeff could be precalculated into a table
538 * but it seems to be slower on x86
540 * TIA/EIA/IS-733 2.4.3.3.5
542 static void lspf2lpc(const float *lspf, float *lpc)
545 double bandwidth_expansion_coeff = QCELP_BANDWIDTH_EXPANSION_COEFF;
549 lsp[i] = cos(M_PI * lspf[i]);
551 ff_acelp_lspd2lpc(lsp, lpc, 5);
553 for (i = 0; i < 10; i++) {
554 lpc[i] *= bandwidth_expansion_coeff;
555 bandwidth_expansion_coeff *= QCELP_BANDWIDTH_EXPANSION_COEFF;
560 * Interpolate LSP frequencies and compute LPC coefficients
561 * for a given bitrate & pitch subframe.
563 * TIA/EIA/IS-733 2.4.3.3.4, 2.4.8.7.2
565 * @param q the context
566 * @param curr_lspf LSP frequencies vector of the current frame
567 * @param lpc float vector for the resulting LPC
568 * @param subframe_num frame number in decoded stream
570 static void interpolate_lpc(QCELPContext *q, const float *curr_lspf,
571 float *lpc, const int subframe_num)
573 float interpolated_lspf[10];
576 if(q->bitrate >= RATE_QUARTER)
577 weight = 0.25 * (subframe_num + 1);
578 else if(q->bitrate == RATE_OCTAVE && !subframe_num)
584 ff_weighted_vector_sumf(interpolated_lspf, curr_lspf, q->prev_lspf,
585 weight, 1.0 - weight, 10);
586 lspf2lpc(interpolated_lspf, lpc);
587 }else if(q->bitrate >= RATE_QUARTER ||
588 (q->bitrate == I_F_Q && !subframe_num))
589 lspf2lpc(curr_lspf, lpc);
590 else if(q->bitrate == SILENCE && !subframe_num)
591 lspf2lpc(q->prev_lspf, lpc);
594 static qcelp_packet_rate buf_size2bitrate(const int buf_size)
597 case 35: return RATE_FULL;
598 case 17: return RATE_HALF;
599 case 8: return RATE_QUARTER;
600 case 4: return RATE_OCTAVE;
601 case 1: return SILENCE;
608 * Determine the bitrate from the frame size and/or the first byte of the frame.
610 * @param avctx the AV codec context
611 * @param buf_size length of the buffer
612 * @param buf the bufffer
614 * @return the bitrate on success,
615 * I_F_Q if the bitrate cannot be satisfactorily determined
617 * TIA/EIA/IS-733 2.4.8.7.1
619 static qcelp_packet_rate determine_bitrate(AVCodecContext *avctx, const int buf_size,
622 qcelp_packet_rate bitrate;
624 if ((bitrate = buf_size2bitrate(buf_size)) >= 0) {
625 if (bitrate > **buf) {
626 QCELPContext *q = avctx->priv_data;
627 if (!q->warned_buf_mismatch_bitrate) {
628 av_log(avctx, AV_LOG_WARNING,
629 "Claimed bitrate and buffer size mismatch.\n");
630 q->warned_buf_mismatch_bitrate = 1;
633 } else if (bitrate < **buf) {
634 av_log(avctx, AV_LOG_ERROR,
635 "Buffer is too small for the claimed bitrate.\n");
639 } else if ((bitrate = buf_size2bitrate(buf_size + 1)) >= 0) {
640 av_log(avctx, AV_LOG_WARNING,
641 "Bitrate byte is missing, guessing the bitrate from packet size.\n");
645 if (bitrate == SILENCE) {
646 //FIXME: Remove experimental warning when tested with samples.
647 av_log_ask_for_sample(avctx, "'Blank frame handling is experimental.");
652 static void warn_insufficient_frame_quality(AVCodecContext *avctx,
655 av_log(avctx, AV_LOG_WARNING, "Frame #%d, IFQ: %s\n", avctx->frame_number,
659 static void postfilter(QCELPContext *q, float *samples, float *lpc)
661 static const float pow_0_775[10] = {
662 0.775000, 0.600625, 0.465484, 0.360750, 0.279582,
663 0.216676, 0.167924, 0.130141, 0.100859, 0.078166
665 0.625000, 0.390625, 0.244141, 0.152588, 0.095367,
666 0.059605, 0.037253, 0.023283, 0.014552, 0.009095
668 float lpc_s[10], lpc_p[10], pole_out[170], zero_out[160];
671 for (n = 0; n < 10; n++) {
672 lpc_s[n] = lpc[n] * pow_0_625[n];
673 lpc_p[n] = lpc[n] * pow_0_775[n];
676 ff_celp_lp_zero_synthesis_filterf(zero_out, lpc_s,
677 q->formant_mem + 10, 160, 10);
678 memcpy(pole_out, q->postfilter_synth_mem, sizeof(float) * 10);
679 ff_celp_lp_synthesis_filterf(pole_out + 10, lpc_p, zero_out, 160, 10);
680 memcpy(q->postfilter_synth_mem, pole_out + 160, sizeof(float) * 10);
682 ff_tilt_compensation(&q->postfilter_tilt_mem, 0.3, pole_out + 10, 160);
684 ff_adaptive_gain_control(samples, pole_out + 10,
685 ff_dot_productf(q->formant_mem + 10, q->formant_mem + 10, 160),
686 160, 0.9375, &q->postfilter_agc_mem);
689 static int qcelp_decode_frame(AVCodecContext *avctx, void *data,
690 int *got_frame_ptr, AVPacket *avpkt)
692 const uint8_t *buf = avpkt->data;
693 int buf_size = avpkt->size;
694 QCELPContext *q = avctx->priv_data;
697 float quantized_lspf[10], lpc[10];
701 /* get output buffer */
702 q->avframe.nb_samples = 160;
703 if ((ret = avctx->get_buffer(avctx, &q->avframe)) < 0) {
704 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
707 outbuffer = (float *)q->avframe.data[0];
709 if ((q->bitrate = determine_bitrate(avctx, buf_size, &buf)) == I_F_Q) {
710 warn_insufficient_frame_quality(avctx, "bitrate cannot be determined.");
714 if(q->bitrate == RATE_OCTAVE &&
715 (q->first16bits = AV_RB16(buf)) == 0xFFFF) {
716 warn_insufficient_frame_quality(avctx, "Bitrate is 1/8 and first 16 bits are on.");
720 if (q->bitrate > SILENCE) {
721 const QCELPBitmap *bitmaps = qcelp_unpacking_bitmaps_per_rate[q->bitrate];
722 const QCELPBitmap *bitmaps_end = qcelp_unpacking_bitmaps_per_rate[q->bitrate]
723 + qcelp_unpacking_bitmaps_lengths[q->bitrate];
724 uint8_t *unpacked_data = (uint8_t *)&q->frame;
726 init_get_bits(&q->gb, buf, 8*buf_size);
728 memset(&q->frame, 0, sizeof(QCELPFrame));
730 for(; bitmaps < bitmaps_end; bitmaps++)
731 unpacked_data[bitmaps->index] |= get_bits(&q->gb, bitmaps->bitlen) << bitmaps->bitpos;
733 // Check for erasures/blanks on rates 1, 1/4 and 1/8.
734 if (q->frame.reserved) {
735 warn_insufficient_frame_quality(avctx, "Wrong data in reserved frame area.");
738 if(q->bitrate == RATE_QUARTER &&
739 codebook_sanity_check_for_rate_quarter(q->frame.cbgain)) {
740 warn_insufficient_frame_quality(avctx, "Codebook gain sanity check failed.");
744 if (q->bitrate >= RATE_HALF) {
745 for (i = 0; i < 4; i++) {
746 if (q->frame.pfrac[i] && q->frame.plag[i] >= 124) {
747 warn_insufficient_frame_quality(avctx, "Cannot initialize pitch filter.");
754 decode_gain_and_index(q, gain);
755 compute_svector(q, gain, outbuffer);
757 if (decode_lspf(q, quantized_lspf) < 0) {
758 warn_insufficient_frame_quality(avctx, "Badly received packets in frame.");
763 apply_pitch_filters(q, outbuffer);
765 if (q->bitrate == I_F_Q) {
769 decode_gain_and_index(q, gain);
770 compute_svector(q, gain, outbuffer);
771 decode_lspf(q, quantized_lspf);
772 apply_pitch_filters(q, outbuffer);
774 q->erasure_count = 0;
776 formant_mem = q->formant_mem + 10;
777 for (i = 0; i < 4; i++) {
778 interpolate_lpc(q, quantized_lspf, lpc, i);
779 ff_celp_lp_synthesis_filterf(formant_mem, lpc, outbuffer + i * 40, 40,
784 // postfilter, as per TIA/EIA/IS-733 2.4.8.6
785 postfilter(q, outbuffer, lpc);
787 memcpy(q->formant_mem, q->formant_mem + 160, 10 * sizeof(float));
789 memcpy(q->prev_lspf, quantized_lspf, sizeof(q->prev_lspf));
790 q->prev_bitrate = q->bitrate;
793 *(AVFrame *)data = q->avframe;
798 AVCodec ff_qcelp_decoder =
801 .type = AVMEDIA_TYPE_AUDIO,
802 .id = CODEC_ID_QCELP,
803 .init = qcelp_decode_init,
804 .decode = qcelp_decode_frame,
805 .capabilities = CODEC_CAP_DR1,
806 .priv_data_size = sizeof(QCELPContext),
807 .long_name = NULL_IF_CONFIG_SMALL("QCELP / PureVoice"),