| 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 |