FFmpeg coverage

Line	Branch	Exec	Source
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 "decode.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			*/
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
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			*/
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
221		✗	static void warn_insufficient_frame_quality(AVCodecContext *avctx,
222			const char *message)
223			{
224		✗	av_log(avctx, AV_LOG_WARNING, "Frame #%"PRId64", %s\n",
225			avctx->frame_num, message);
226		✗	}
227
228			/**
229			* Initialize the speech codec according to the specification.
230			*
231			* TIA/IS-127 5.2
232			*/
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			*/
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			*/
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			*/
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			*/
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
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			*/
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
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
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			*/
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			*/
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
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
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			*/
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
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
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			CODEC_LONG_NAME("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			};
943