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1 | /* |
2 | * audio resampling | |
3 | * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at> | |
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 | * audio resampling | |
25 | * @author Michael Niedermayer <michaelni@gmx.at> | |
26 | */ | |
27 | ||
28 | #include "libavutil/avassert.h" | |
29 | #include "avcodec.h" | |
30 | #include "libavutil/common.h" | |
31 | ||
32 | #if FF_API_AVCODEC_RESAMPLE | |
33 | ||
34 | #ifndef CONFIG_RESAMPLE_HP | |
35 | #define FILTER_SHIFT 15 | |
36 | ||
37 | #define FELEM int16_t | |
38 | #define FELEM2 int32_t | |
39 | #define FELEML int64_t | |
40 | #define FELEM_MAX INT16_MAX | |
41 | #define FELEM_MIN INT16_MIN | |
42 | #define WINDOW_TYPE 9 | |
43 | #elif !defined(CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE) | |
44 | #define FILTER_SHIFT 30 | |
45 | ||
46 | #define FELEM int32_t | |
47 | #define FELEM2 int64_t | |
48 | #define FELEML int64_t | |
49 | #define FELEM_MAX INT32_MAX | |
50 | #define FELEM_MIN INT32_MIN | |
51 | #define WINDOW_TYPE 12 | |
52 | #else | |
53 | #define FILTER_SHIFT 0 | |
54 | ||
55 | #define FELEM double | |
56 | #define FELEM2 double | |
57 | #define FELEML double | |
58 | #define WINDOW_TYPE 24 | |
59 | #endif | |
60 | ||
61 | ||
62 | typedef struct AVResampleContext{ | |
63 | const AVClass *av_class; | |
64 | FELEM *filter_bank; | |
65 | int filter_length; | |
66 | int ideal_dst_incr; | |
67 | int dst_incr; | |
68 | int index; | |
69 | int frac; | |
70 | int src_incr; | |
71 | int compensation_distance; | |
72 | int phase_shift; | |
73 | int phase_mask; | |
74 | int linear; | |
75 | }AVResampleContext; | |
76 | ||
77 | /** | |
78 | * 0th order modified bessel function of the first kind. | |
79 | */ | |
80 | static double bessel(double x){ | |
81 | double v=1; | |
82 | double lastv=0; | |
83 | double t=1; | |
84 | int i; | |
85 | ||
86 | x= x*x/4; | |
87 | for(i=1; v != lastv; i++){ | |
88 | lastv=v; | |
89 | t *= x/(i*i); | |
90 | v += t; | |
91 | } | |
92 | return v; | |
93 | } | |
94 | ||
95 | /** | |
96 | * Build a polyphase filterbank. | |
97 | * @param factor resampling factor | |
98 | * @param scale wanted sum of coefficients for each filter | |
99 | * @param type 0->cubic, 1->blackman nuttall windowed sinc, 2..16->kaiser windowed sinc beta=2..16 | |
100 | * @return 0 on success, negative on error | |
101 | */ | |
102 | static int build_filter(FELEM *filter, double factor, int tap_count, int phase_count, int scale, int type){ | |
103 | int ph, i; | |
104 | double x, y, w; | |
105 | double *tab = av_malloc_array(tap_count, sizeof(*tab)); | |
106 | const int center= (tap_count-1)/2; | |
107 | ||
108 | if (!tab) | |
109 | return AVERROR(ENOMEM); | |
110 | ||
111 | /* if upsampling, only need to interpolate, no filter */ | |
112 | if (factor > 1.0) | |
113 | factor = 1.0; | |
114 | ||
115 | for(ph=0;ph<phase_count;ph++) { | |
116 | double norm = 0; | |
117 | for(i=0;i<tap_count;i++) { | |
118 | x = M_PI * ((double)(i - center) - (double)ph / phase_count) * factor; | |
119 | if (x == 0) y = 1.0; | |
120 | else y = sin(x) / x; | |
121 | switch(type){ | |
122 | case 0:{ | |
123 | const float d= -0.5; //first order derivative = -0.5 | |
124 | x = fabs(((double)(i - center) - (double)ph / phase_count) * factor); | |
125 | if(x<1.0) y= 1 - 3*x*x + 2*x*x*x + d*( -x*x + x*x*x); | |
126 | else y= d*(-4 + 8*x - 5*x*x + x*x*x); | |
127 | break;} | |
128 | case 1: | |
129 | w = 2.0*x / (factor*tap_count) + M_PI; | |
130 | y *= 0.3635819 - 0.4891775 * cos(w) + 0.1365995 * cos(2*w) - 0.0106411 * cos(3*w); | |
131 | break; | |
132 | default: | |
133 | w = 2.0*x / (factor*tap_count*M_PI); | |
134 | y *= bessel(type*sqrt(FFMAX(1-w*w, 0))); | |
135 | break; | |
136 | } | |
137 | ||
138 | tab[i] = y; | |
139 | norm += y; | |
140 | } | |
141 | ||
142 | /* normalize so that an uniform color remains the same */ | |
143 | for(i=0;i<tap_count;i++) { | |
144 | #ifdef CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE | |
145 | filter[ph * tap_count + i] = tab[i] / norm; | |
146 | #else | |
147 | filter[ph * tap_count + i] = av_clip(lrintf(tab[i] * scale / norm), FELEM_MIN, FELEM_MAX); | |
148 | #endif | |
149 | } | |
150 | } | |
151 | #if 0 | |
152 | { | |
153 | #define LEN 1024 | |
154 | int j,k; | |
155 | double sine[LEN + tap_count]; | |
156 | double filtered[LEN]; | |
157 | double maxff=-2, minff=2, maxsf=-2, minsf=2; | |
158 | for(i=0; i<LEN; i++){ | |
159 | double ss=0, sf=0, ff=0; | |
160 | for(j=0; j<LEN+tap_count; j++) | |
161 | sine[j]= cos(i*j*M_PI/LEN); | |
162 | for(j=0; j<LEN; j++){ | |
163 | double sum=0; | |
164 | ph=0; | |
165 | for(k=0; k<tap_count; k++) | |
166 | sum += filter[ph * tap_count + k] * sine[k+j]; | |
167 | filtered[j]= sum / (1<<FILTER_SHIFT); | |
168 | ss+= sine[j + center] * sine[j + center]; | |
169 | ff+= filtered[j] * filtered[j]; | |
170 | sf+= sine[j + center] * filtered[j]; | |
171 | } | |
172 | ss= sqrt(2*ss/LEN); | |
173 | ff= sqrt(2*ff/LEN); | |
174 | sf= 2*sf/LEN; | |
175 | maxff= FFMAX(maxff, ff); | |
176 | minff= FFMIN(minff, ff); | |
177 | maxsf= FFMAX(maxsf, sf); | |
178 | minsf= FFMIN(minsf, sf); | |
179 | if(i%11==0){ | |
180 | av_log(NULL, AV_LOG_ERROR, "i:%4d ss:%f ff:%13.6e-%13.6e sf:%13.6e-%13.6e\n", i, ss, maxff, minff, maxsf, minsf); | |
181 | minff=minsf= 2; | |
182 | maxff=maxsf= -2; | |
183 | } | |
184 | } | |
185 | } | |
186 | #endif | |
187 | ||
188 | av_free(tab); | |
189 | return 0; | |
190 | } | |
191 | ||
192 | AVResampleContext *av_resample_init(int out_rate, int in_rate, int filter_size, int phase_shift, int linear, double cutoff){ | |
193 | AVResampleContext *c= av_mallocz(sizeof(AVResampleContext)); | |
194 | double factor= FFMIN(out_rate * cutoff / in_rate, 1.0); | |
195 | int phase_count= 1<<phase_shift; | |
196 | ||
197 | if (!c) | |
198 | return NULL; | |
199 | ||
200 | c->phase_shift= phase_shift; | |
201 | c->phase_mask= phase_count-1; | |
202 | c->linear= linear; | |
203 | ||
204 | c->filter_length= FFMAX((int)ceil(filter_size/factor), 1); | |
205 | c->filter_bank= av_mallocz_array(c->filter_length, (phase_count+1)*sizeof(FELEM)); | |
206 | if (!c->filter_bank) | |
207 | goto error; | |
208 | if (build_filter(c->filter_bank, factor, c->filter_length, phase_count, 1<<FILTER_SHIFT, WINDOW_TYPE)) | |
209 | goto error; | |
210 | memcpy(&c->filter_bank[c->filter_length*phase_count+1], c->filter_bank, (c->filter_length-1)*sizeof(FELEM)); | |
211 | c->filter_bank[c->filter_length*phase_count]= c->filter_bank[c->filter_length - 1]; | |
212 | ||
213 | if(!av_reduce(&c->src_incr, &c->dst_incr, out_rate, in_rate * (int64_t)phase_count, INT32_MAX/2)) | |
214 | goto error; | |
215 | c->ideal_dst_incr= c->dst_incr; | |
216 | ||
217 | c->index= -phase_count*((c->filter_length-1)/2); | |
218 | ||
219 | return c; | |
220 | error: | |
221 | av_free(c->filter_bank); | |
222 | av_free(c); | |
223 | return NULL; | |
224 | } | |
225 | ||
226 | void av_resample_close(AVResampleContext *c){ | |
227 | av_freep(&c->filter_bank); | |
228 | av_freep(&c); | |
229 | } | |
230 | ||
231 | void av_resample_compensate(AVResampleContext *c, int sample_delta, int compensation_distance){ | |
232 | // sample_delta += (c->ideal_dst_incr - c->dst_incr)*(int64_t)c->compensation_distance / c->ideal_dst_incr; | |
233 | c->compensation_distance= compensation_distance; | |
234 | c->dst_incr = c->ideal_dst_incr - c->ideal_dst_incr * (int64_t)sample_delta / compensation_distance; | |
235 | } | |
236 | ||
237 | int av_resample(AVResampleContext *c, short *dst, short *src, int *consumed, int src_size, int dst_size, int update_ctx){ | |
238 | int dst_index, i; | |
239 | int index= c->index; | |
240 | int frac= c->frac; | |
241 | int dst_incr_frac= c->dst_incr % c->src_incr; | |
242 | int dst_incr= c->dst_incr / c->src_incr; | |
243 | int compensation_distance= c->compensation_distance; | |
244 | ||
245 | if(compensation_distance == 0 && c->filter_length == 1 && c->phase_shift==0){ | |
246 | int64_t index2= ((int64_t)index)<<32; | |
247 | int64_t incr= (1LL<<32) * c->dst_incr / c->src_incr; | |
248 | dst_size= FFMIN(dst_size, (src_size-1-index) * (int64_t)c->src_incr / c->dst_incr); | |
249 | ||
250 | for(dst_index=0; dst_index < dst_size; dst_index++){ | |
251 | dst[dst_index] = src[index2>>32]; | |
252 | index2 += incr; | |
253 | } | |
254 | index += dst_index * dst_incr; | |
255 | index += (frac + dst_index * (int64_t)dst_incr_frac) / c->src_incr; | |
256 | frac = (frac + dst_index * (int64_t)dst_incr_frac) % c->src_incr; | |
257 | }else{ | |
258 | for(dst_index=0; dst_index < dst_size; dst_index++){ | |
259 | FELEM *filter= c->filter_bank + c->filter_length*(index & c->phase_mask); | |
260 | int sample_index= index >> c->phase_shift; | |
261 | FELEM2 val=0; | |
262 | ||
263 | if(sample_index < 0){ | |
264 | for(i=0; i<c->filter_length; i++) | |
265 | val += src[FFABS(sample_index + i) % src_size] * filter[i]; | |
266 | }else if(sample_index + c->filter_length > src_size){ | |
267 | break; | |
268 | }else if(c->linear){ | |
269 | FELEM2 v2=0; | |
270 | for(i=0; i<c->filter_length; i++){ | |
271 | val += src[sample_index + i] * (FELEM2)filter[i]; | |
272 | v2 += src[sample_index + i] * (FELEM2)filter[i + c->filter_length]; | |
273 | } | |
274 | val+=(v2-val)*(FELEML)frac / c->src_incr; | |
275 | }else{ | |
276 | for(i=0; i<c->filter_length; i++){ | |
277 | val += src[sample_index + i] * (FELEM2)filter[i]; | |
278 | } | |
279 | } | |
280 | ||
281 | #ifdef CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE | |
282 | dst[dst_index] = av_clip_int16(lrintf(val)); | |
283 | #else | |
284 | val = (val + (1<<(FILTER_SHIFT-1)))>>FILTER_SHIFT; | |
285 | dst[dst_index] = (unsigned)(val + 32768) > 65535 ? (val>>31) ^ 32767 : val; | |
286 | #endif | |
287 | ||
288 | frac += dst_incr_frac; | |
289 | index += dst_incr; | |
290 | if(frac >= c->src_incr){ | |
291 | frac -= c->src_incr; | |
292 | index++; | |
293 | } | |
294 | ||
295 | if(dst_index + 1 == compensation_distance){ | |
296 | compensation_distance= 0; | |
297 | dst_incr_frac= c->ideal_dst_incr % c->src_incr; | |
298 | dst_incr= c->ideal_dst_incr / c->src_incr; | |
299 | } | |
300 | } | |
301 | } | |
302 | *consumed= FFMAX(index, 0) >> c->phase_shift; | |
303 | if(index>=0) index &= c->phase_mask; | |
304 | ||
305 | if(compensation_distance){ | |
306 | compensation_distance -= dst_index; | |
307 | av_assert2(compensation_distance > 0); | |
308 | } | |
309 | if(update_ctx){ | |
310 | c->frac= frac; | |
311 | c->index= index; | |
312 | c->dst_incr= dst_incr_frac + c->src_incr*dst_incr; | |
313 | c->compensation_distance= compensation_distance; | |
314 | } | |
315 | ||
316 | return dst_index; | |
317 | } | |
318 | ||
319 | #endif |