FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/lpc.c
Date: 2021-09-23 20:34:37
Exec Total Coverage
Lines: 137 150 91.3%
Branches: 75 88 85.2%

Line Branch Exec Source
1 /*
2 * LPC utility code
3 * Copyright (c) 2006 Justin Ruggles <justin.ruggles@gmail.com>
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 #include "libavutil/common.h"
23 #include "libavutil/lls.h"
24 #include "libavutil/mem_internal.h"
25
26 #define LPC_USE_DOUBLE
27 #include "lpc.h"
28 #include "libavutil/avassert.h"
29
30
31 /**
32 * Apply Welch window function to audio block
33 */
34 3969 static void lpc_apply_welch_window_c(const int32_t *data, int len,
35 double *w_data)
36 {
37 int i, n2;
38 double w;
39 double c;
40
41 3969 n2 = (len >> 1);
42 3969 c = 2.0 / (len - 1.0);
43
44
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3969 if (len & 1) {
45
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1050 for(i=0; i<n2; i++) {
46 1048 w = c - i - 1.0;
47 1048 w = 1.0 - (w * w);
48 1048 w_data[i] = data[i] * w;
49 1048 w_data[len-1-i] = data[len-1-i] * w;
50 }
51 2 return;
52 }
53
54 3967 w_data+=n2;
55 3967 data+=n2;
56
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9253857 for(i=0; i<n2; i++) {
57 9249890 w = c - n2 + i;
58 9249890 w = 1.0 - (w * w);
59 9249890 w_data[-i-1] = data[-i-1] * w;
60 9249890 w_data[+i ] = data[+i ] * w;
61 }
62 }
63
64 /**
65 * Calculate autocorrelation data from audio samples
66 * A Welch window function is applied before calculation.
67 */
68 6116 static void lpc_compute_autocorr_c(const double *data, int len, int lag,
69 double *autoc)
70 {
71 int i, j;
72
73
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46495 for(j=0; j<lag; j+=2){
74 40379 double sum0 = 1.0, sum1 = 1.0;
75
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135340869 for(i=j; i<len; i++){
76 135300490 sum0 += data[i] * data[i-j];
77 135300490 sum1 += data[i] * data[i-j-1];
78 }
79 40379 autoc[j ] = sum0;
80 40379 autoc[j+1] = sum1;
81 }
82
83
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6116 if(j==lag){
84 5820 double sum = 1.0;
85
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9806155 for(i=j-1; i<len; i+=2){
86 9800335 sum += data[i ] * data[i-j ]
87 9800335 + data[i+1] * data[i-j+1];
88 }
89 5820 autoc[j] = sum;
90 }
91 6116 }
92
93 /**
94 * Quantize LPC coefficients
95 */
96 11765 static void quantize_lpc_coefs(double *lpc_in, int order, int precision,
97 int32_t *lpc_out, int *shift, int min_shift,
98 int max_shift, int zero_shift)
99 {
100 int i;
101 double cmax, error;
102 int32_t qmax;
103 int sh;
104
105 /* define maximum levels */
106 11765 qmax = (1 << (precision - 1)) - 1;
107
108 /* find maximum coefficient value */
109 11765 cmax = 0.0;
110
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69630 for(i=0; i<order; i++) {
111
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57865 cmax= FFMAX(cmax, fabs(lpc_in[i]));
112 }
113
114 /* if maximum value quantizes to zero, return all zeros */
115
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11765 if(cmax * (1 << max_shift) < 1.0) {
116 *shift = zero_shift;
117 memset(lpc_out, 0, sizeof(int32_t) * order);
118 return;
119 }
120
121 /* calculate level shift which scales max coeff to available bits */
122 11765 sh = max_shift;
123
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32239 while((cmax * (1 << sh) > qmax) && (sh > min_shift)) {
124 20474 sh--;
125 }
126
127 /* since negative shift values are unsupported in decoder, scale down
128 coefficients instead */
129
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11765 if(sh == 0 && cmax > qmax) {
130 double scale = ((double)qmax) / cmax;
131 for(i=0; i<order; i++) {
132 lpc_in[i] *= scale;
133 }
134 }
135
136 /* output quantized coefficients and level shift */
137 11765 error=0;
138
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69630 for(i=0; i<order; i++) {
139 57865 error -= lpc_in[i] * (1 << sh);
140 57865 lpc_out[i] = av_clip(lrintf(error), -qmax, qmax);
141 57865 error -= lpc_out[i];
142 }
143 11765 *shift = sh;
144 }
145
146 8933 static int estimate_best_order(double *ref, int min_order, int max_order)
147 {
148 int i, est;
149
150 8933 est = min_order;
151
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64596 for(i=max_order-1; i>=min_order-1; i--) {
152
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64422 if(ref[i] > 0.10) {
153 8759 est = i+1;
154 8759 break;
155 }
156 }
157 8933 return est;
158 }
159
160 int ff_lpc_calc_ref_coefs(LPCContext *s,
161 const int32_t *samples, int order, double *ref)
162 {
163 double autoc[MAX_LPC_ORDER + 1];
164
165 s->lpc_apply_welch_window(samples, s->blocksize, s->windowed_samples);
166 s->lpc_compute_autocorr(s->windowed_samples, s->blocksize, order, autoc);
167 compute_ref_coefs(autoc, order, ref, NULL);
168
169 return order;
170 }
171
172 2147 double ff_lpc_calc_ref_coefs_f(LPCContext *s, const float *samples, int len,
173 int order, double *ref)
174 {
175 int i;
176 2147 double signal = 0.0f, avg_err = 0.0f;
177 2147 double autoc[MAX_LPC_ORDER+1] = {0}, error[MAX_LPC_ORDER+1] = {0};
178 2147 const double a = 0.5f, b = 1.0f - a;
179
180 /* Apply windowing */
181
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602762 for (i = 0; i <= len / 2; i++) {
182 600615 double weight = a - b*cos((2*M_PI*i)/(len - 1));
183 600615 s->windowed_samples[i] = weight*samples[i];
184 600615 s->windowed_samples[len-1-i] = weight*samples[len-1-i];
185 }
186
187 2147 s->lpc_compute_autocorr(s->windowed_samples, len, order, autoc);
188 2147 signal = autoc[0];
189 2147 compute_ref_coefs(autoc, order, ref, error);
190
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26431 for (i = 0; i < order; i++)
191 24284 avg_err = (avg_err + error[i])/2.0f;
192
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2147 return avg_err ? signal/avg_err : NAN;
193 }
194
195 /**
196 * Calculate LPC coefficients for multiple orders
197 *
198 * @param lpc_type LPC method for determining coefficients,
199 * see #FFLPCType for details
200 */
201 9169 int ff_lpc_calc_coefs(LPCContext *s,
202 const int32_t *samples, int blocksize, int min_order,
203 int max_order, int precision,
204 int32_t coefs[][MAX_LPC_ORDER], int *shift,
205 enum FFLPCType lpc_type, int lpc_passes,
206 int omethod, int min_shift, int max_shift, int zero_shift)
207 {
208 double autoc[MAX_LPC_ORDER+1];
209 9169 double ref[MAX_LPC_ORDER] = { 0 };
210 double lpc[MAX_LPC_ORDER][MAX_LPC_ORDER];
211 9169 int i, j, pass = 0;
212 int opt_order;
213
214 av_assert2(max_order >= MIN_LPC_ORDER && max_order <= MAX_LPC_ORDER &&
215 lpc_type > FF_LPC_TYPE_FIXED);
216
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9169 av_assert0(lpc_type == FF_LPC_TYPE_CHOLESKY || lpc_type == FF_LPC_TYPE_LEVINSON);
217
218 /* reinit LPC context if parameters have changed */
219
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9169 if (blocksize != s->blocksize || max_order != s->max_order ||
220
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9156 lpc_type != s->lpc_type) {
221 14 ff_lpc_end(s);
222 14 ff_lpc_init(s, blocksize, max_order, lpc_type);
223 }
224
225
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9169 if(lpc_passes <= 0)
226 2589 lpc_passes = 2;
227
228
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9169 if (lpc_type == FF_LPC_TYPE_LEVINSON || (lpc_type == FF_LPC_TYPE_CHOLESKY && lpc_passes > 1)) {
229 9169 s->lpc_apply_welch_window(samples, blocksize, s->windowed_samples);
230
231 9169 s->lpc_compute_autocorr(s->windowed_samples, blocksize, max_order, autoc);
232
233 9169 compute_lpc_coefs(autoc, max_order, &lpc[0][0], MAX_LPC_ORDER, 0, 1);
234
235
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106947 for(i=0; i<max_order; i++)
236 97778 ref[i] = fabs(lpc[i][i]);
237
238 9169 pass++;
239 }
240
241
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9169 if (lpc_type == FF_LPC_TYPE_CHOLESKY) {
242 182 LLSModel *m = s->lls_models;
243 182 LOCAL_ALIGNED(32, double, var, [FFALIGN(MAX_LPC_ORDER+1,4)]);
244 182 double av_uninit(weight);
245 182 memset(var, 0, FFALIGN(MAX_LPC_ORDER+1,4)*sizeof(*var));
246
247
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1638 for(j=0; j<max_order; j++)
248 1456 m[0].coeff[max_order-1][j] = -lpc[max_order-1][j];
249
250
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364 for(; pass<lpc_passes; pass++){
251 182 avpriv_init_lls(&m[pass&1], max_order);
252
253 182 weight=0;
254
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836626 for(i=max_order; i<blocksize; i++){
255
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8364440 for(j=0; j<=max_order; j++)
256 7527996 var[j]= samples[i-j];
257
258
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836444 if(pass){
259 double eval, inv, rinv;
260 836444 eval= m[pass&1].evaluate_lls(&m[(pass-1)&1], var+1, max_order-1);
261 836444 eval= (512>>pass) + fabs(eval - var[0]);
262 836444 inv = 1/eval;
263 836444 rinv = sqrt(inv);
264
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8364440 for(j=0; j<=max_order; j++)
265 7527996 var[j] *= rinv;
266 836444 weight += inv;
267 }else
268 weight++;
269
270 836444 m[pass&1].update_lls(&m[pass&1], var);
271 }
272 182 avpriv_solve_lls(&m[pass&1], 0.001, 0);
273 }
274
275
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1638 for(i=0; i<max_order; i++){
276
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13104 for(j=0; j<max_order; j++)
277 11648 lpc[i][j]=-m[(pass-1)&1].coeff[i][j];
278 1456 ref[i]= sqrt(m[(pass-1)&1].variance[i] / weight) * (blocksize - max_order) / 4000;
279 }
280
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1456 for(i=max_order-1; i>0; i--)
281 1274 ref[i] = ref[i-1] - ref[i];
282 }
283
284 9169 opt_order = max_order;
285
286
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9169 if(omethod == ORDER_METHOD_EST) {
287 8933 opt_order = estimate_best_order(ref, min_order, max_order);
288 8933 i = opt_order-1;
289 8933 quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i],
290 min_shift, max_shift, zero_shift);
291 } else {
292
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3068 for(i=min_order-1; i<max_order; i++) {
293 2832 quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i],
294 min_shift, max_shift, zero_shift);
295 }
296 }
297
298 9169 return opt_order;
299 }
300
301 66 av_cold int ff_lpc_init(LPCContext *s, int blocksize, int max_order,
302 enum FFLPCType lpc_type)
303 {
304 66 s->blocksize = blocksize;
305 66 s->max_order = max_order;
306 66 s->lpc_type = lpc_type;
307
308 66 s->windowed_buffer = av_mallocz((blocksize + 2 + FFALIGN(max_order, 4)) *
309 sizeof(*s->windowed_samples));
310
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66 if (!s->windowed_buffer)
311 return AVERROR(ENOMEM);
312 66 s->windowed_samples = s->windowed_buffer + FFALIGN(max_order, 4);
313
314 66 s->lpc_apply_welch_window = lpc_apply_welch_window_c;
315 66 s->lpc_compute_autocorr = lpc_compute_autocorr_c;
316
317 if (ARCH_X86)
318 66 ff_lpc_init_x86(s);
319
320 66 return 0;
321 }
322
323 66 av_cold void ff_lpc_end(LPCContext *s)
324 {
325 66 av_freep(&s->windowed_buffer);
326 66 }
327