Change to file description suggested by Michael
[libav.git] / libavcodec / 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 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 * @file qcelpdec.c
23 * QCELP decoder
24 * @author Reynaldo H. Verdejo Pinochet
25 */
26
27#include <stddef.h>
28
29#include "avcodec.h"
30#include "bitstream.h"
31
32#include "qcelp.h"
33#include "qcelpdata.h"
34
35#include "celp_math.h"
36#include "celp_filters.h"
37
38#undef NDEBUG
39#include <assert.h>
40
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41static void weighted_vector_sumf(float *out,
42 const float *in_a,
43 const float *in_b,
44 float weight_coeff_a,
45 float weight_coeff_b,
46 int length) {
47 int i;
48
49 for (i = 0; i < length; i++)
50 out[i] = weight_coeff_a * in_a[i]
51 + weight_coeff_b * in_b[i];
52}
53
cb377ec5 54/**
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55 * Initialize the speech codec according to the specification.
56 *
57 * TIA/EIA/IS-733 2.4.9
58 */
59static av_cold int qcelp_decode_init(AVCodecContext *avctx) {
60 QCELPContext *q = avctx->priv_data;
61 int i;
62
63 avctx->sample_fmt = SAMPLE_FMT_FLT;
64
65 for (i = 0; i < 10; i++)
66 q->prev_lspf[i] = (i + 1) / 11.;
67
68 return 0;
69}
70
71/**
72 * Computes the scaled codebook vector Cdn From INDEX and GAIN
73 * for all rates.
74 *
75 * The specification lacks some information here.
76 *
77 * TIA/EIA/IS-733 has an omission on the codebook index determination
78 * formula for RATE_FULL and RATE_HALF frames at section 2.4.8.1.1. It says
79 * you have to subtract the decoded index parameter from the given scaled
80 * codebook vector index 'n' to get the desired circular codebook index, but
81 * it does not mention that you have to clamp 'n' to [0-9] in order to get
82 * RI-compliant results.
83 *
84 * The reason for this mistake seems to be the fact they forgot to mention you
85 * have to do these calculations per codebook subframe and adjust given
86 * equation values accordingly.
87 *
88 * @param q the context
89 * @param gain array holding the 4 pitch subframe gain values
90 * @param cdn_vector array for the generated scaled codebook vector
91 */
92static void compute_svector(const QCELPContext *q,
93 const float *gain,
94 float *cdn_vector) {
95 int i, j, k;
96 uint16_t cbseed, cindex;
97 float *rnd, tmp_gain, fir_filter_value;
98
99 switch (q->framerate) {
100 case RATE_FULL:
101 for (i = 0; i < 16; i++) {
102 tmp_gain = gain[i] * QCELP_RATE_FULL_CODEBOOK_RATIO;
103 cindex = -q->cindex[i];
104 for (j = 0; j < 10; j++)
105 *cdn_vector++ = tmp_gain * qcelp_rate_full_codebook[cindex++ & 127];
106 }
107 break;
108 case RATE_HALF:
109 for (i = 0; i < 4; i++) {
110 tmp_gain = gain[i] * QCELP_RATE_HALF_CODEBOOK_RATIO;
111 cindex = -q->cindex[i];
112 for (j = 0; j < 40; j++)
113 *cdn_vector++ = tmp_gain * qcelp_rate_half_codebook[cindex++ & 127];
114 }
115 break;
116 case RATE_QUARTER:
117 cbseed = (0x0003 & q->lspv[4])<<14 |
118 (0x003F & q->lspv[3])<< 8 |
119 (0x0060 & q->lspv[2])<< 1 |
120 (0x0007 & q->lspv[1])<< 3 |
121 (0x0038 & q->lspv[0])>> 3 ;
122 rnd = q->rnd_fir_filter_mem + 20;
123 for (i = 0; i < 8; i++) {
124 tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
125 for (k = 0; k < 20; k++) {
126 cbseed = 521 * cbseed + 259;
127 *rnd = (int16_t)cbseed;
128
129 // FIR filter
130 fir_filter_value = 0.0;
131 for (j = 0; j < 10; j++)
132 fir_filter_value += qcelp_rnd_fir_coefs[j ] * (rnd[-j ] + rnd[-20+j]);
133 fir_filter_value += qcelp_rnd_fir_coefs[10] * rnd[-10];
134
135 *cdn_vector++ = tmp_gain * fir_filter_value;
136 rnd++;
137 }
138 }
139 memcpy(q->rnd_fir_filter_mem, q->rnd_fir_filter_mem + 160, 20 * sizeof(float));
140 break;
141 case RATE_OCTAVE:
142 cbseed = q->first16bits;
143 for (i = 0; i < 8; i++) {
144 tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
145 for (j = 0; j < 20; j++) {
146 cbseed = 521 * cbseed + 259;
147 *cdn_vector++ = tmp_gain * (int16_t)cbseed;
148 }
149 }
150 break;
151 case I_F_Q:
152 cbseed = -44; // random codebook index
153 for (i = 0; i < 4; i++) {
154 tmp_gain = gain[i] * QCELP_RATE_FULL_CODEBOOK_RATIO;
155 for (j = 0; j < 40; j++)
156 *cdn_vector++ = tmp_gain * qcelp_rate_full_codebook[cbseed++ & 127];
157 }
158 break;
159 }
160}
161
162/**
163 * Apply generic gain control.
164 *
165 * @param v_out output vector
166 * @param v_in gain-controlled vector
167 * @param v_ref vector to control gain of
168 *
169 * FIXME: If v_ref is a zero vector, it energy is zero
170 * and the behavior of the gain control is
171 * undefined in the specs.
172 *
173 * TIA/EIA/IS-733 2.4.8.3-2/3/4/5, 2.4.8.6
174 */
175static void apply_gain_ctrl(float *v_out,
176 const float *v_ref,
177 const float *v_in) {
178 int i, j, len;
179 float scalefactor;
180
181 for (i = 0, j = 0; i < 4; i++) {
182 scalefactor = ff_dot_productf(v_in + j, v_in + j, 40);
183 if (scalefactor)
184 scalefactor = sqrt(ff_dot_productf(v_ref + j, v_ref + j, 40) / scalefactor);
185 else
186 av_log_missing_feature(NULL, "Zero energy for gain control", 1);
187 for (len = j + 40; j < len; j++)
188 v_out[j] = scalefactor * v_in[j];
189 }
190}
191
192/**
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193 * Apply filter in pitch-subframe steps.
194 *
195 * @param memory buffer for the previous state of the filter
196 * - must be able to contain 303 elements
197 * - the 143 first elements are from the previous state
198 * - the next 160 are for output
199 * @param v_in input filter vector
200 * @param gain per-subframe gain array, each element is between 0.0 and 2.0
201 * @param lag per-subframe lag array, each element is
202 * - between 16 and 143 if its corresponding pfrac is 0,
203 * - between 16 and 139 otherwise
204 * @param pfrac per-subframe boolean array, 1 if the lag is fractional, 0 otherwise
205 *
206 * @return filter output vector
207 */
208static const float *do_pitchfilter(float memory[303],
209 const float v_in[160],
210 const float gain[4],
211 const uint8_t *lag,
212 const uint8_t pfrac[4]) {
213 int i, j;
214 float *v_lag, *v_out;
215 const float *v_len;
216
217 v_out = memory + 143; // Output vector starts at memory[143].
218
219 for (i = 0; i < 4; i++)
220 if (gain[i]) {
221 v_lag = memory + 143 + 40 * i - lag[i];
222 for (v_len = v_in + 40; v_in < v_len; v_in++) {
223 if (pfrac[i]) { // If it is a fractional lag...
224 for (j = 0, *v_out = 0.; j < 4; j++)
225 *v_out += qcelp_hammsinc_table[j] * (v_lag[j-4] + v_lag[3-j]);
226 } else
227 *v_out = *v_lag;
228
229 *v_out = *v_in + gain[i] * *v_out;
230
231 v_lag++;
232 v_out++;
233 }
234 } else {
235 memcpy(v_out, v_in, 40 * sizeof(float));
236 v_in += 40;
237 v_out += 40;
238 }
239
240 memmove(memory, memory + 160, 143 * sizeof(float));
241 return memory + 143;
242}
243
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244/**
245 * Interpolates LSP frequencies and computes LPC coefficients
246 * for a given framerate & pitch subframe.
247 *
248 * TIA/EIA/IS-733 2.4.3.3.4
249 *
250 * @param q the context
251 * @param curr_lspf LSP frequencies vector of the current frame
252 * @param lpc float vector for the resulting LPC
253 * @param subframe_num frame number in decoded stream
254 */
255void interpolate_lpc(QCELPContext *q,
256 const float *curr_lspf,
257 float *lpc,
258 const int subframe_num) {
259 float interpolated_lspf[10];
260 float weight;
261
262 if (q->framerate >= RATE_QUARTER) {
263 weight = 0.25 * (subframe_num + 1);
264 } else if (q->framerate == RATE_OCTAVE && !subframe_num) {
265 weight = 0.625;
266 } else {
267 weight = 1.0;
268 }
269
270 if (weight != 1.0) {
271 weighted_vector_sumf(interpolated_lspf, curr_lspf, q->prev_lspf, weight, 1.0 - weight, 10);
39ded680 272 qcelp_lspf2lpc(interpolated_lspf, lpc);
200de8c6 273 } else if (q->framerate >= RATE_QUARTER || (q->framerate == I_F_Q && !subframe_num))
39ded680 274 qcelp_lspf2lpc(curr_lspf, lpc);
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275}
276
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277static int buf_size2framerate(const int buf_size) {
278 switch (buf_size) {
279 case 35:
280 return RATE_FULL;
281 case 17:
282 return RATE_HALF;
283 case 8:
284 return RATE_QUARTER;
285 case 4:
286 return RATE_OCTAVE;
287 case 1:
288 return SILENCE;
289 }
290 return -1;
291}
292
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293static void warn_insufficient_frame_quality(AVCodecContext *avctx,
294 const char *message) {
295 av_log(avctx, AV_LOG_WARNING, "Frame #%d, IFQ: %s\n", avctx->frame_number, message);
296}
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297
298AVCodec qcelp_decoder =
299{
300 .name = "qcelp",
301 .type = CODEC_TYPE_AUDIO,
302 .id = CODEC_ID_QCELP,
303 .init = qcelp_decode_init,
304 .decode = qcelp_decode_frame,
305 .priv_data_size = sizeof(QCELPContext),
306 .long_name = NULL_IF_CONFIG_SMALL("QCELP / PureVoice"),
307};