1 /*
2 * Enhanced Variable Rate Codec, Service Option 3 decoder
3 * Copyright (c) 2013 Paul B Mahol
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 * Enhanced Variable Rate Codec, Service Option 3 decoder
25 * @author Paul B Mahol
26 */
27
28 #include "libavutil/channel_layout.h"
29 #include "libavutil/mathematics.h"
30 #include "libavutil/opt.h"
31 #include "avcodec.h"
32 #include "codec_internal.h"
33 #include "internal.h"
34 #include "get_bits.h"
35 #include "evrcdata.h"
36 #include "acelp_vectors.h"
37 #include "lsp.h"
38
39 #define MIN_LSP_SEP (0.05 / (2.0 * M_PI))
40 #define MIN_DELAY 20
41 #define MAX_DELAY 120
42 #define NB_SUBFRAMES 3
43 #define SUBFRAME_SIZE 54
44 #define FILTER_ORDER 10
45 #define ACB_SIZE 128
46
47 typedef enum {
48 RATE_ERRS = -1,
49 SILENCE,
50 RATE_QUANT,
51 RATE_QUARTER,
52 RATE_HALF,
53 RATE_FULL,
54 } evrc_packet_rate;
55
56 /**
57 * EVRC-A unpacked data frame
58 */
59 typedef struct EVRCAFrame {
60 uint8_t lpc_flag; ///< spectral change indicator
61 uint16_t lsp[4]; ///< index into LSP codebook
62 uint8_t pitch_delay; ///< pitch delay for entire frame
63 uint8_t delay_diff; ///< delay difference for entire frame
64 uint8_t acb_gain[3]; ///< adaptive codebook gain
65 uint16_t fcb_shape[3][4]; ///< fixed codebook shape
66 uint8_t fcb_gain[3]; ///< fixed codebook gain index
67 uint8_t energy_gain; ///< frame energy gain index
68 uint8_t tty; ///< tty baud rate bit
69 } EVRCAFrame;
70
71 typedef struct EVRCContext {
72 AVClass *class;
73
74 int postfilter;
75
76 GetBitContext gb;
77 evrc_packet_rate bitrate;
78 evrc_packet_rate last_valid_bitrate;
79 EVRCAFrame frame;
80
81 float lspf[FILTER_ORDER];
82 float prev_lspf[FILTER_ORDER];
83 float synthesis[FILTER_ORDER];
84 float postfilter_fir[FILTER_ORDER];
85 float postfilter_iir[FILTER_ORDER];
86 float postfilter_residual[ACB_SIZE + SUBFRAME_SIZE];
87 float pitch_delay;
88 float prev_pitch_delay;
89 float avg_acb_gain; ///< average adaptive codebook gain
90 float avg_fcb_gain; ///< average fixed codebook gain
91 float pitch[ACB_SIZE + FILTER_ORDER + SUBFRAME_SIZE];
92 float pitch_back[ACB_SIZE];
93 float interpolation_coeffs[136];
94 float energy_vector[NB_SUBFRAMES];
95 float fade_scale;
96 float last;
97
98 uint8_t prev_energy_gain;
99 uint8_t prev_error_flag;
100 uint8_t warned_buf_mismatch_bitrate;
101 } EVRCContext;
102
103 /**
104 * Frame unpacking for RATE_FULL, RATE_HALF and RATE_QUANT
105 *
106 * @param e the context
107 *
108 * TIA/IS-127 Table 4.21-1
109 */
unpack_frame(EVRCContext *e)110 static void unpack_frame(EVRCContext *e)
111 {
112 EVRCAFrame *frame = &e->frame;
113 GetBitContext *gb = &e->gb;
114
115 switch (e->bitrate) {
116 case RATE_FULL:
117 frame->lpc_flag = get_bits1(gb);
118 frame->lsp[0] = get_bits(gb, 6);
119 frame->lsp[1] = get_bits(gb, 6);
120 frame->lsp[2] = get_bits(gb, 9);
121 frame->lsp[3] = get_bits(gb, 7);
122 frame->pitch_delay = get_bits(gb, 7);
123 frame->delay_diff = get_bits(gb, 5);
124 frame->acb_gain[0] = get_bits(gb, 3);
125 frame->fcb_shape[0][0] = get_bits(gb, 8);
126 frame->fcb_shape[0][1] = get_bits(gb, 8);
127 frame->fcb_shape[0][2] = get_bits(gb, 8);
128 frame->fcb_shape[0][3] = get_bits(gb, 11);
129 frame->fcb_gain[0] = get_bits(gb, 5);
130 frame->acb_gain[1] = get_bits(gb, 3);
131 frame->fcb_shape[1][0] = get_bits(gb, 8);
132 frame->fcb_shape[1][1] = get_bits(gb, 8);
133 frame->fcb_shape[1][2] = get_bits(gb, 8);
134 frame->fcb_shape[1][3] = get_bits(gb, 11);
135 frame->fcb_gain [1] = get_bits(gb, 5);
136 frame->acb_gain [2] = get_bits(gb, 3);
137 frame->fcb_shape[2][0] = get_bits(gb, 8);
138 frame->fcb_shape[2][1] = get_bits(gb, 8);
139 frame->fcb_shape[2][2] = get_bits(gb, 8);
140 frame->fcb_shape[2][3] = get_bits(gb, 11);
141 frame->fcb_gain [2] = get_bits(gb, 5);
142 frame->tty = get_bits1(gb);
143 break;
144 case RATE_HALF:
145 frame->lsp [0] = get_bits(gb, 7);
146 frame->lsp [1] = get_bits(gb, 7);
147 frame->lsp [2] = get_bits(gb, 8);
148 frame->pitch_delay = get_bits(gb, 7);
149 frame->acb_gain [0] = get_bits(gb, 3);
150 frame->fcb_shape[0][0] = get_bits(gb, 10);
151 frame->fcb_gain [0] = get_bits(gb, 4);
152 frame->acb_gain [1] = get_bits(gb, 3);
153 frame->fcb_shape[1][0] = get_bits(gb, 10);
154 frame->fcb_gain [1] = get_bits(gb, 4);
155 frame->acb_gain [2] = get_bits(gb, 3);
156 frame->fcb_shape[2][0] = get_bits(gb, 10);
157 frame->fcb_gain [2] = get_bits(gb, 4);
158 break;
159 case RATE_QUANT:
160 frame->lsp [0] = get_bits(gb, 4);
161 frame->lsp [1] = get_bits(gb, 4);
162 frame->energy_gain = get_bits(gb, 8);
163 break;
164 }
165 }
166
buf_size2bitrate(const int buf_size)167 static evrc_packet_rate buf_size2bitrate(const int buf_size)
168 {
169 switch (buf_size) {
170 case 23: return RATE_FULL;
171 case 11: return RATE_HALF;
172 case 6: return RATE_QUARTER;
173 case 3: return RATE_QUANT;
174 case 1: return SILENCE;
175 }
176
177 return RATE_ERRS;
178 }
179
180 /**
181 * Determine the bitrate from the frame size and/or the first byte of the frame.
182 *
183 * @param avctx the AV codec context
184 * @param buf_size length of the buffer
185 * @param buf the bufffer
186 *
187 * @return the bitrate on success,
188 * RATE_ERRS if the bitrate cannot be satisfactorily determined
189 */
determine_bitrate(AVCodecContext *avctx, int *buf_size, const uint8_t **buf)190 static evrc_packet_rate determine_bitrate(AVCodecContext *avctx,
191 int *buf_size,
192 const uint8_t **buf)
193 {
194 evrc_packet_rate bitrate;
195
196 if ((bitrate = buf_size2bitrate(*buf_size)) >= 0) {
197 if (bitrate > **buf) {
198 EVRCContext *e = avctx->priv_data;
199 if (!e->warned_buf_mismatch_bitrate) {
200 av_log(avctx, AV_LOG_WARNING,
201 "Claimed bitrate and buffer size mismatch.\n");
202 e->warned_buf_mismatch_bitrate = 1;
203 }
204 bitrate = **buf;
205 } else if (bitrate < **buf) {
206 av_log(avctx, AV_LOG_ERROR,
207 "Buffer is too small for the claimed bitrate.\n");
208 return RATE_ERRS;
209 }
210 (*buf)++;
211 *buf_size -= 1;
212 } else if ((bitrate = buf_size2bitrate(*buf_size + 1)) >= 0) {
213 av_log(avctx, AV_LOG_DEBUG,
214 "Bitrate byte is missing, guessing the bitrate from packet size.\n");
215 } else
216 return RATE_ERRS;
217
218 return bitrate;
219 }
220
warn_insufficient_frame_quality(AVCodecContext *avctx, const char *message)221 static void warn_insufficient_frame_quality(AVCodecContext *avctx,
222 const char *message)
223 {
224 av_log(avctx, AV_LOG_WARNING, "Frame #%d, %s\n",
225 avctx->frame_number, message);
226 }
227
228 /**
229 * Initialize the speech codec according to the specification.
230 *
231 * TIA/IS-127 5.2
232 */
evrc_decode_init(AVCodecContext *avctx)233 static av_cold int evrc_decode_init(AVCodecContext *avctx)
234 {
235 EVRCContext *e = avctx->priv_data;
236 int i, n, idx = 0;
237 float denom = 2.0 / (2.0 * 8.0 + 1.0);
238
239 av_channel_layout_uninit(&avctx->ch_layout);
240 avctx->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;
241 avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
242
243 for (i = 0; i < FILTER_ORDER; i++) {
244 e->prev_lspf[i] = (i + 1) * 0.048;
245 e->synthesis[i] = 0.0;
246 }
247
248 for (i = 0; i < ACB_SIZE; i++)
249 e->pitch[i] = e->pitch_back[i] = 0.0;
250
251 e->last_valid_bitrate = RATE_QUANT;
252 e->prev_pitch_delay = 40.0;
253 e->fade_scale = 1.0;
254 e->prev_error_flag = 0;
255 e->avg_acb_gain = e->avg_fcb_gain = 0.0;
256
257 for (i = 0; i < 8; i++) {
258 float tt = ((float)i - 8.0 / 2.0) / 8.0;
259
260 for (n = -8; n <= 8; n++, idx++) {
261 float arg1 = M_PI * 0.9 * (tt - n);
262 float arg2 = M_PI * (tt - n);
263
264 e->interpolation_coeffs[idx] = 0.9;
265 if (arg1)
266 e->interpolation_coeffs[idx] *= (0.54 + 0.46 * cos(arg2 * denom)) *
267 sin(arg1) / arg1;
268 }
269 }
270
271 return 0;
272 }
273
274 /**
275 * Decode the 10 vector quantized line spectral pair frequencies from the LSP
276 * transmission codes of any bitrate and check for badly received packets.
277 *
278 * @param e the context
279 *
280 * @return 0 on success, -1 if the packet is badly received
281 *
282 * TIA/IS-127 5.2.1, 5.7.1
283 */
decode_lspf(EVRCContext *e)284 static int decode_lspf(EVRCContext *e)
285 {
286 const float * const *codebooks = evrc_lspq_codebooks[e->bitrate];
287 int i, j, k = 0;
288
289 for (i = 0; i < evrc_lspq_nb_codebooks[e->bitrate]; i++) {
290 int row_size = evrc_lspq_codebooks_row_sizes[e->bitrate][i];
291 const float *codebook = codebooks[i];
292
293 for (j = 0; j < row_size; j++)
294 e->lspf[k++] = codebook[e->frame.lsp[i] * row_size + j];
295 }
296
297 // check for monotonic LSPs
298 for (i = 1; i < FILTER_ORDER; i++)
299 if (e->lspf[i] <= e->lspf[i - 1])
300 return -1;
301
302 // check for minimum separation of LSPs at the splits
303 for (i = 0, k = 0; i < evrc_lspq_nb_codebooks[e->bitrate] - 1; i++) {
304 k += evrc_lspq_codebooks_row_sizes[e->bitrate][i];
305 if (e->lspf[k] - e->lspf[k - 1] <= MIN_LSP_SEP)
306 return -1;
307 }
308
309 return 0;
310 }
311
312 /*
313 * Interpolation of LSP parameters.
314 *
315 * TIA/IS-127 5.2.3.1, 5.7.3.2
316 */
interpolate_lsp(float *ilsp, const float *lsp, const float *prev, int index)317 static void interpolate_lsp(float *ilsp, const float *lsp,
318 const float *prev, int index)
319 {
320 static const float lsp_interpolation_factors[] = { 0.1667, 0.5, 0.8333 };
321 ff_weighted_vector_sumf(ilsp, prev, lsp,
322 1.0 - lsp_interpolation_factors[index],
323 lsp_interpolation_factors[index], FILTER_ORDER);
324 }
325
326 /*
327 * Reconstruction of the delay contour.
328 *
329 * TIA/IS-127 5.2.2.3.2
330 */
interpolate_delay(float *dst, float current, float prev, int index)331 static void interpolate_delay(float *dst, float current, float prev, int index)
332 {
333 static const float d_interpolation_factors[] = { 0, 0.3313, 0.6625, 1, 1 };
334 dst[0] = (1.0 - d_interpolation_factors[index ]) * prev
335 + d_interpolation_factors[index ] * current;
336 dst[1] = (1.0 - d_interpolation_factors[index + 1]) * prev
337 + d_interpolation_factors[index + 1] * current;
338 dst[2] = (1.0 - d_interpolation_factors[index + 2]) * prev
339 + d_interpolation_factors[index + 2] * current;
340 }
341
342 /*
343 * Convert the quantized, interpolated line spectral frequencies,
344 * to prediction coefficients.
345 *
346 * TIA/IS-127 5.2.3.2, 4.7.2.2
347 */
decode_predictor_coeffs(const float *ilspf, float *ilpc)348 static void decode_predictor_coeffs(const float *ilspf, float *ilpc)
349 {
350 double lsp[FILTER_ORDER];
351 float a[FILTER_ORDER / 2 + 1], b[FILTER_ORDER / 2 + 1];
352 float a1[FILTER_ORDER / 2] = { 0 };
353 float a2[FILTER_ORDER / 2] = { 0 };
354 float b1[FILTER_ORDER / 2] = { 0 };
355 float b2[FILTER_ORDER / 2] = { 0 };
356 int i, k;
357
358 ff_acelp_lsf2lspd(lsp, ilspf, FILTER_ORDER);
359
360 for (k = 0; k <= FILTER_ORDER; k++) {
361 a[0] = k < 2 ? 0.25 : 0;
362 b[0] = k < 2 ? k < 1 ? 0.25 : -0.25 : 0;
363
364 for (i = 0; i < FILTER_ORDER / 2; i++) {
365 a[i + 1] = a[i] - 2 * lsp[i * 2 ] * a1[i] + a2[i];
366 b[i + 1] = b[i] - 2 * lsp[i * 2 + 1] * b1[i] + b2[i];
367 a2[i] = a1[i];
368 a1[i] = a[i];
369 b2[i] = b1[i];
370 b1[i] = b[i];
371 }
372
373 if (k)
374 ilpc[k - 1] = 2.0 * (a[FILTER_ORDER / 2] + b[FILTER_ORDER / 2]);
375 }
376 }
377
bl_intrp(EVRCContext *e, float *ex, float delay)378 static void bl_intrp(EVRCContext *e, float *ex, float delay)
379 {
380 float *f;
381 int offset, i, coef_idx;
382 int16_t t;
383
384 offset = lrintf(delay);
385
386 t = (offset - delay + 0.5) * 8.0 + 0.5;
387 if (t == 8) {
388 t = 0;
389 offset--;
390 }
391
392 f = ex - offset - 8;
393
394 coef_idx = t * (2 * 8 + 1);
395
396 ex[0] = 0.0;
397 for (i = 0; i < 2 * 8 + 1; i++)
398 ex[0] += e->interpolation_coeffs[coef_idx + i] * f[i];
399 }
400
401 /*
402 * Adaptive codebook excitation.
403 *
404 * TIA/IS-127 5.2.2.3.3, 4.12.5.2
405 */
acb_excitation(EVRCContext *e, float *excitation, float gain, const float delay[3], int length)406 static void acb_excitation(EVRCContext *e, float *excitation, float gain,
407 const float delay[3], int length)
408 {
409 float denom, locdelay, dpr, invl;
410 int i;
411
412 invl = 1.0 / ((float) length);
413 dpr = length;
414
415 /* first at-most extra samples */
416 denom = (delay[1] - delay[0]) * invl;
417 for (i = 0; i < dpr; i++) {
418 locdelay = delay[0] + i * denom;
419 bl_intrp(e, excitation + i, locdelay);
420 }
421
422 denom = (delay[2] - delay[1]) * invl;
423 /* interpolation */
424 for (i = dpr; i < dpr + 10; i++) {
425 locdelay = delay[1] + (i - dpr) * denom;
426 bl_intrp(e, excitation + i, locdelay);
427 }
428
429 for (i = 0; i < length; i++)
430 excitation[i] *= gain;
431 }
432
decode_8_pulses_35bits(const uint16_t *fixed_index, float *cod)433 static void decode_8_pulses_35bits(const uint16_t *fixed_index, float *cod)
434 {
435 int i, pos1, pos2, offset;
436
437 offset = (fixed_index[3] >> 9) & 3;
438
439 for (i = 0; i < 3; i++) {
440 pos1 = ((fixed_index[i] & 0x7f) / 11) * 5 + ((i + offset) % 5);
441 pos2 = ((fixed_index[i] & 0x7f) % 11) * 5 + ((i + offset) % 5);
442
443 cod[pos1] = (fixed_index[i] & 0x80) ? -1.0 : 1.0;
444
445 if (pos2 < pos1)
446 cod[pos2] = -cod[pos1];
447 else
448 cod[pos2] += cod[pos1];
449 }
450
451 pos1 = ((fixed_index[3] & 0x7f) / 11) * 5 + ((3 + offset) % 5);
452 pos2 = ((fixed_index[3] & 0x7f) % 11) * 5 + ((4 + offset) % 5);
453
454 cod[pos1] = (fixed_index[3] & 0x100) ? -1.0 : 1.0;
455 cod[pos2] = (fixed_index[3] & 0x80 ) ? -1.0 : 1.0;
456 }
457
decode_3_pulses_10bits(uint16_t fixed_index, float *cod)458 static void decode_3_pulses_10bits(uint16_t fixed_index, float *cod)
459 {
460 float sign;
461 int pos;
462
463 sign = (fixed_index & 0x200) ? -1.0 : 1.0;
464
465 pos = ((fixed_index & 0x7) * 7) + 4;
466 cod[pos] += sign;
467 pos = (((fixed_index >> 3) & 0x7) * 7) + 2;
468 cod[pos] -= sign;
469 pos = (((fixed_index >> 6) & 0x7) * 7);
470 cod[pos] += sign;
471 }
472
473 /*
474 * Reconstruction of ACELP fixed codebook excitation for full and half rate.
475 *
476 * TIA/IS-127 5.2.3.7
477 */
fcb_excitation(EVRCContext *e, const uint16_t *codebook, float *excitation, float pitch_gain, int pitch_lag, int subframe_size)478 static void fcb_excitation(EVRCContext *e, const uint16_t *codebook,
479 float *excitation, float pitch_gain,
480 int pitch_lag, int subframe_size)
481 {
482 int i;
483
484 if (e->bitrate == RATE_FULL)
485 decode_8_pulses_35bits(codebook, excitation);
486 else
487 decode_3_pulses_10bits(*codebook, excitation);
488
489 pitch_gain = av_clipf(pitch_gain, 0.2, 0.9);
490
491 for (i = pitch_lag; i < subframe_size; i++)
492 excitation[i] += pitch_gain * excitation[i - pitch_lag];
493 }
494
495 /**
496 * Synthesis of the decoder output signal.
497 *
498 * param[in] in input signal
499 * param[in] filter_coeffs LPC coefficients
500 * param[in/out] memory synthesis filter memory
501 * param buffer_length amount of data to process
502 * param[out] samples output samples
503 *
504 * TIA/IS-127 5.2.3.15, 5.7.3.4
505 */
synthesis_filter(const float *in, const float *filter_coeffs, float *memory, int buffer_length, float *samples)506 static void synthesis_filter(const float *in, const float *filter_coeffs,
507 float *memory, int buffer_length, float *samples)
508 {
509 int i, j;
510
511 for (i = 0; i < buffer_length; i++) {
512 samples[i] = in[i];
513 for (j = FILTER_ORDER - 1; j > 0; j--) {
514 samples[i] -= filter_coeffs[j] * memory[j];
515 memory[j] = memory[j - 1];
516 }
517 samples[i] -= filter_coeffs[0] * memory[0];
518 memory[0] = samples[i];
519 }
520 }
521
bandwidth_expansion(float *coeff, const float *inbuf, float gamma)522 static void bandwidth_expansion(float *coeff, const float *inbuf, float gamma)
523 {
524 double fac = gamma;
525 int i;
526
527 for (i = 0; i < FILTER_ORDER; i++) {
528 coeff[i] = inbuf[i] * fac;
529 fac *= gamma;
530 }
531 }
532
residual_filter(float *output, const float *input, const float *coef, float *memory, int length)533 static void residual_filter(float *output, const float *input,
534 const float *coef, float *memory, int length)
535 {
536 float sum;
537 int i, j;
538
539 for (i = 0; i < length; i++) {
540 sum = input[i];
541
542 for (j = FILTER_ORDER - 1; j > 0; j--) {
543 sum += coef[j] * memory[j];
544 memory[j] = memory[j - 1];
545 }
546 sum += coef[0] * memory[0];
547 memory[0] = input[i];
548 output[i] = sum;
549 }
550 }
551
552 /*
553 * TIA/IS-127 Table 5.9.1-1.
554 */
555 static const struct PfCoeff {
556 float tilt;
557 float ltgain;
558 float p1;
559 float p2;
560 } postfilter_coeffs[5] = {
561 { 0.0 , 0.0 , 0.0 , 0.0 },
562 { 0.0 , 0.0 , 0.57, 0.57 },
563 { 0.0 , 0.0 , 0.0 , 0.0 },
564 { 0.35, 0.50, 0.50, 0.75 },
565 { 0.20, 0.50, 0.57, 0.75 },
566 };
567
568 /*
569 * Adaptive postfilter.
570 *
571 * TIA/IS-127 5.9
572 */
postfilter(EVRCContext *e, float *in, const float *coeff, float *out, int idx, const struct PfCoeff *pfc, int length)573 static void postfilter(EVRCContext *e, float *in, const float *coeff,
574 float *out, int idx, const struct PfCoeff *pfc,
575 int length)
576 {
577 float wcoef1[FILTER_ORDER], wcoef2[FILTER_ORDER],
578 scratch[SUBFRAME_SIZE], temp[SUBFRAME_SIZE],
579 mem[SUBFRAME_SIZE];
580 float sum1 = 0.0, sum2 = 0.0, gamma, gain;
581 float tilt = pfc->tilt;
582 int i, n, best;
583
584 bandwidth_expansion(wcoef1, coeff, pfc->p1);
585 bandwidth_expansion(wcoef2, coeff, pfc->p2);
586
587 /* Tilt compensation filter, TIA/IS-127 5.9.1 */
588 for (i = 0; i < length - 1; i++)
589 sum2 += in[i] * in[i + 1];
590 if (sum2 < 0.0)
591 tilt = 0.0;
592
593 for (i = 0; i < length; i++) {
594 scratch[i] = in[i] - tilt * e->last;
595 e->last = in[i];
596 }
597
598 /* Short term residual filter, TIA/IS-127 5.9.2 */
599 residual_filter(&e->postfilter_residual[ACB_SIZE], scratch, wcoef1, e->postfilter_fir, length);
600
601 /* Long term postfilter */
602 best = idx;
603 for (i = FFMIN(MIN_DELAY, idx - 3); i <= FFMAX(MAX_DELAY, idx + 3); i++) {
604 for (n = ACB_SIZE, sum2 = 0; n < ACB_SIZE + length; n++)
605 sum2 += e->postfilter_residual[n] * e->postfilter_residual[n - i];
606 if (sum2 > sum1) {
607 sum1 = sum2;
608 best = i;
609 }
610 }
611
612 for (i = ACB_SIZE, sum1 = 0; i < ACB_SIZE + length; i++)
613 sum1 += e->postfilter_residual[i - best] * e->postfilter_residual[i - best];
614 for (i = ACB_SIZE, sum2 = 0; i < ACB_SIZE + length; i++)
615 sum2 += e->postfilter_residual[i] * e->postfilter_residual[i - best];
616
617 if (sum2 * sum1 == 0 || e->bitrate == RATE_QUANT) {
618 memcpy(temp, e->postfilter_residual + ACB_SIZE, length * sizeof(float));
619 } else {
620 gamma = sum2 / sum1;
621 if (gamma < 0.5)
622 memcpy(temp, e->postfilter_residual + ACB_SIZE, length * sizeof(float));
623 else {
624 gamma = FFMIN(gamma, 1.0);
625
626 for (i = 0; i < length; i++) {
627 temp[i] = e->postfilter_residual[ACB_SIZE + i] + gamma *
628 pfc->ltgain * e->postfilter_residual[ACB_SIZE + i - best];
629 }
630 }
631 }
632
633 memcpy(scratch, temp, length * sizeof(float));
634 memcpy(mem, e->postfilter_iir, FILTER_ORDER * sizeof(float));
635 synthesis_filter(scratch, wcoef2, mem, length, scratch);
636
637 /* Gain computation, TIA/IS-127 5.9.4-2 */
638 for (i = 0, sum1 = 0, sum2 = 0; i < length; i++) {
639 sum1 += in[i] * in[i];
640 sum2 += scratch[i] * scratch[i];
641 }
642 gain = sum2 ? sqrt(sum1 / sum2) : 1.0;
643
644 for (i = 0; i < length; i++)
645 temp[i] *= gain;
646
647 /* Short term postfilter */
648 synthesis_filter(temp, wcoef2, e->postfilter_iir, length, out);
649
650 memmove(e->postfilter_residual,
651 e->postfilter_residual + length, ACB_SIZE * sizeof(float));
652 }
653
frame_erasure(EVRCContext *e, float *samples)654 static void frame_erasure(EVRCContext *e, float *samples)
655 {
656 float ilspf[FILTER_ORDER], ilpc[FILTER_ORDER], idelay[NB_SUBFRAMES],
657 tmp[SUBFRAME_SIZE + 6], f;
658 int i, j;
659
660 for (i = 0; i < FILTER_ORDER; i++) {
661 if (e->bitrate != RATE_QUANT)
662 e->lspf[i] = e->prev_lspf[i] * 0.875 + 0.125 * (i + 1) * 0.048;
663 else
664 e->lspf[i] = e->prev_lspf[i];
665 }
666
667 if (e->prev_error_flag)
668 e->avg_acb_gain *= 0.75;
669 if (e->bitrate == RATE_FULL)
670 memcpy(e->pitch_back, e->pitch, ACB_SIZE * sizeof(float));
671 if (e->last_valid_bitrate == RATE_QUANT)
672 e->bitrate = RATE_QUANT;
673 else
674 e->bitrate = RATE_FULL;
675
676 if (e->bitrate == RATE_FULL || e->bitrate == RATE_HALF) {
677 e->pitch_delay = e->prev_pitch_delay;
678 } else {
679 float sum = 0;
680
681 idelay[0] = idelay[1] = idelay[2] = MIN_DELAY;
682
683 for (i = 0; i < NB_SUBFRAMES; i++)
684 sum += evrc_energy_quant[e->prev_energy_gain][i];
685 sum /= (float) NB_SUBFRAMES;
686 sum = pow(10, sum);
687 for (i = 0; i < NB_SUBFRAMES; i++)
688 e->energy_vector[i] = sum;
689 }
690
691 if (fabs(e->pitch_delay - e->prev_pitch_delay) > 15)
692 e->prev_pitch_delay = e->pitch_delay;
693
694 for (i = 0; i < NB_SUBFRAMES; i++) {
695 int subframe_size = subframe_sizes[i];
696 int pitch_lag;
697
698 interpolate_lsp(ilspf, e->lspf, e->prev_lspf, i);
699
700 if (e->bitrate != RATE_QUANT) {
701 if (e->avg_acb_gain < 0.3) {
702 idelay[0] = estimation_delay[i];
703 idelay[1] = estimation_delay[i + 1];
704 idelay[2] = estimation_delay[i + 2];
705 } else {
706 interpolate_delay(idelay, e->pitch_delay, e->prev_pitch_delay, i);
707 }
708 }
709
710 pitch_lag = lrintf((idelay[1] + idelay[0]) / 2.0);
711 decode_predictor_coeffs(ilspf, ilpc);
712
713 if (e->bitrate != RATE_QUANT) {
714 acb_excitation(e, e->pitch + ACB_SIZE,
715 e->avg_acb_gain, idelay, subframe_size);
716 for (j = 0; j < subframe_size; j++)
717 e->pitch[ACB_SIZE + j] *= e->fade_scale;
718 e->fade_scale = FFMAX(e->fade_scale - 0.05, 0.0);
719 } else {
720 for (j = 0; j < subframe_size; j++)
721 e->pitch[ACB_SIZE + j] = e->energy_vector[i];
722 }
723
724 memmove(e->pitch, e->pitch + subframe_size, ACB_SIZE * sizeof(float));
725
726 if (e->bitrate != RATE_QUANT && e->avg_acb_gain < 0.4) {
727 f = 0.1 * e->avg_fcb_gain;
728 for (j = 0; j < subframe_size; j++)
729 e->pitch[ACB_SIZE + j] += f;
730 } else if (e->bitrate == RATE_QUANT) {
731 for (j = 0; j < subframe_size; j++)
732 e->pitch[ACB_SIZE + j] = e->energy_vector[i];
733 }
734
735 synthesis_filter(e->pitch + ACB_SIZE, ilpc,
736 e->synthesis, subframe_size, tmp);
737 postfilter(e, tmp, ilpc, samples, pitch_lag,
738 &postfilter_coeffs[e->bitrate], subframe_size);
739
740 samples += subframe_size;
741 }
742 }
743
evrc_decode_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame_ptr, AVPacket *avpkt)744 static int evrc_decode_frame(AVCodecContext *avctx, AVFrame *frame,
745 int *got_frame_ptr, AVPacket *avpkt)
746 {
747 const uint8_t *buf = avpkt->data;
748 EVRCContext *e = avctx->priv_data;
749 int buf_size = avpkt->size;
750 float ilspf[FILTER_ORDER], ilpc[FILTER_ORDER], idelay[NB_SUBFRAMES];
751 float *samples;
752 int i, j, ret, error_flag = 0;
753
754 frame->nb_samples = 160;
755 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
756 return ret;
757 samples = (float *)frame->data[0];
758
759 if ((e->bitrate = determine_bitrate(avctx, &buf_size, &buf)) == RATE_ERRS) {
760 warn_insufficient_frame_quality(avctx, "bitrate cannot be determined.");
761 goto erasure;
762 }
763 if (e->bitrate <= SILENCE || e->bitrate == RATE_QUARTER)
764 goto erasure;
765 if (e->bitrate == RATE_QUANT && e->last_valid_bitrate == RATE_FULL
766 && !e->prev_error_flag)
767 goto erasure;
768
769 if ((ret = init_get_bits8(&e->gb, buf, buf_size)) < 0)
770 return ret;
771 memset(&e->frame, 0, sizeof(EVRCAFrame));
772
773 unpack_frame(e);
774
775 if (e->bitrate != RATE_QUANT) {
776 uint8_t *p = (uint8_t *) &e->frame;
777 for (i = 0; i < sizeof(EVRCAFrame); i++) {
778 if (p[i])
779 break;
780 }
781 if (i == sizeof(EVRCAFrame))
782 goto erasure;
783 } else if (e->frame.lsp[0] == 0xf &&
784 e->frame.lsp[1] == 0xf &&
785 e->frame.energy_gain == 0xff) {
786 goto erasure;
787 }
788
789 if (decode_lspf(e) < 0)
790 goto erasure;
791
792 if (e->bitrate == RATE_FULL || e->bitrate == RATE_HALF) {
793 /* Pitch delay parameter checking as per TIA/IS-127 5.1.5.1 */
794 if (e->frame.pitch_delay > MAX_DELAY - MIN_DELAY)
795 goto erasure;
796
797 e->pitch_delay = e->frame.pitch_delay + MIN_DELAY;
798
799 /* Delay diff parameter checking as per TIA/IS-127 5.1.5.2 */
800 if (e->frame.delay_diff) {
801 int p = e->pitch_delay - e->frame.delay_diff + 16;
802 if (p < MIN_DELAY || p > MAX_DELAY)
803 goto erasure;
804 }
805
806 /* Delay contour reconstruction as per TIA/IS-127 5.2.2.2 */
807 if (e->frame.delay_diff &&
808 e->bitrate == RATE_FULL && e->prev_error_flag) {
809 float delay;
810
811 memcpy(e->pitch, e->pitch_back, ACB_SIZE * sizeof(float));
812
813 delay = e->prev_pitch_delay;
814 e->prev_pitch_delay = delay - e->frame.delay_diff + 16.0;
815
816 if (fabs(e->pitch_delay - delay) > 15)
817 delay = e->pitch_delay;
818
819 for (i = 0; i < NB_SUBFRAMES; i++) {
820 int subframe_size = subframe_sizes[i];
821
822 interpolate_delay(idelay, delay, e->prev_pitch_delay, i);
823 acb_excitation(e, e->pitch + ACB_SIZE, e->avg_acb_gain, idelay, subframe_size);
824 memmove(e->pitch, e->pitch + subframe_size, ACB_SIZE * sizeof(float));
825 }
826 }
827
828 /* Smoothing of the decoded delay as per TIA/IS-127 5.2.2.5 */
829 if (fabs(e->pitch_delay - e->prev_pitch_delay) > 15)
830 e->prev_pitch_delay = e->pitch_delay;
831
832 e->avg_acb_gain = e->avg_fcb_gain = 0.0;
833 } else {
834 idelay[0] = idelay[1] = idelay[2] = MIN_DELAY;
835
836 /* Decode frame energy vectors as per TIA/IS-127 5.7.2 */
837 for (i = 0; i < NB_SUBFRAMES; i++)
838 e->energy_vector[i] = pow(10, evrc_energy_quant[e->frame.energy_gain][i]);
839 e->prev_energy_gain = e->frame.energy_gain;
840 }
841
842 for (i = 0; i < NB_SUBFRAMES; i++) {
843 float tmp[SUBFRAME_SIZE + 6] = { 0 };
844 int subframe_size = subframe_sizes[i];
845 int pitch_lag;
846
847 interpolate_lsp(ilspf, e->lspf, e->prev_lspf, i);
848
849 if (e->bitrate != RATE_QUANT)
850 interpolate_delay(idelay, e->pitch_delay, e->prev_pitch_delay, i);
851
852 pitch_lag = lrintf((idelay[1] + idelay[0]) / 2.0);
853 decode_predictor_coeffs(ilspf, ilpc);
854
855 /* Bandwidth expansion as per TIA/IS-127 5.2.3.3 */
856 if (e->frame.lpc_flag && e->prev_error_flag)
857 bandwidth_expansion(ilpc, ilpc, 0.75);
858
859 if (e->bitrate != RATE_QUANT) {
860 float acb_sum, f;
861
862 f = exp((e->bitrate == RATE_HALF ? 0.5 : 0.25)
863 * (e->frame.fcb_gain[i] + 1));
864 acb_sum = pitch_gain_vq[e->frame.acb_gain[i]];
865 e->avg_acb_gain += acb_sum / NB_SUBFRAMES;
866 e->avg_fcb_gain += f / NB_SUBFRAMES;
867
868 acb_excitation(e, e->pitch + ACB_SIZE,
869 acb_sum, idelay, subframe_size);
870 fcb_excitation(e, e->frame.fcb_shape[i], tmp,
871 acb_sum, pitch_lag, subframe_size);
872
873 /* Total excitation generation as per TIA/IS-127 5.2.3.9 */
874 for (j = 0; j < subframe_size; j++)
875 e->pitch[ACB_SIZE + j] += f * tmp[j];
876 e->fade_scale = FFMIN(e->fade_scale + 0.2, 1.0);
877 } else {
878 for (j = 0; j < subframe_size; j++)
879 e->pitch[ACB_SIZE + j] = e->energy_vector[i];
880 }
881
882 memmove(e->pitch, e->pitch + subframe_size, ACB_SIZE * sizeof(float));
883
884 synthesis_filter(e->pitch + ACB_SIZE, ilpc,
885 e->synthesis, subframe_size,
886 e->postfilter ? tmp : samples);
887 if (e->postfilter)
888 postfilter(e, tmp, ilpc, samples, pitch_lag,
889 &postfilter_coeffs[e->bitrate], subframe_size);
890
891 samples += subframe_size;
892 }
893
894 if (error_flag) {
895 erasure:
896 error_flag = 1;
897 av_log(avctx, AV_LOG_WARNING, "frame erasure\n");
898 frame_erasure(e, samples);
899 }
900
901 memcpy(e->prev_lspf, e->lspf, sizeof(e->prev_lspf));
902 e->prev_error_flag = error_flag;
903 e->last_valid_bitrate = e->bitrate;
904
905 if (e->bitrate != RATE_QUANT)
906 e->prev_pitch_delay = e->pitch_delay;
907
908 samples = (float *)frame->data[0];
909 for (i = 0; i < 160; i++)
910 samples[i] /= 32768;
911
912 *got_frame_ptr = 1;
913
914 return avpkt->size;
915 }
916
917 #define OFFSET(x) offsetof(EVRCContext, x)
918 #define AD AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_DECODING_PARAM
919
920 static const AVOption options[] = {
921 { "postfilter", "enable postfilter", OFFSET(postfilter), AV_OPT_TYPE_BOOL, {.i64 = 1}, 0, 1, AD },
922 { NULL }
923 };
924
925 static const AVClass evrcdec_class = {
926 .class_name = "evrc",
927 .item_name = av_default_item_name,
928 .option = options,
929 .version = LIBAVUTIL_VERSION_INT,
930 };
931
932 const FFCodec ff_evrc_decoder = {
933 .p.name = "evrc",
934 .p.long_name = NULL_IF_CONFIG_SMALL("EVRC (Enhanced Variable Rate Codec)"),
935 .p.type = AVMEDIA_TYPE_AUDIO,
936 .p.id = AV_CODEC_ID_EVRC,
937 .init = evrc_decode_init,
938 FF_CODEC_DECODE_CB(evrc_decode_frame),
939 .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
940 .priv_data_size = sizeof(EVRCContext),
941 .p.priv_class = &evrcdec_class,
942 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
943 };
944