libavcodec/resample2.c

   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 libavcodec/resample2.c
  24  * audio resampling
  25  * @author Michael Niedermayer <michaelni@gmx.at>
  26  */
  27
  28 #include "avcodec.h"
  29 #include "dsputil.h"
  30
  31 #ifndef CONFIG_RESAMPLE_HP
  32 #define FILTER_SHIFT 15
  33
  34 #define FELEM int16_t
  35 #define FELEM2 int32_t
  36 #define FELEML int64_t
  37 #define FELEM_MAX INT16_MAX
  38 #define FELEM_MIN INT16_MIN
  39 #define WINDOW_TYPE 9
  40 #elif !defined(CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE)
  41 #define FILTER_SHIFT 30
  42
  43 #define FELEM int32_t
  44 #define FELEM2 int64_t
  45 #define FELEML int64_t
  46 #define FELEM_MAX INT32_MAX
  47 #define FELEM_MIN INT32_MIN
  48 #define WINDOW_TYPE 12
  49 #else
  50 #define FILTER_SHIFT 0
  51
  52 #define FELEM double
  53 #define FELEM2 double
  54 #define FELEML double
  55 #define WINDOW_TYPE 24
  56 #endif
  57
  58
  59 typedef struct AVResampleContext{
  60     const AVClass *av_class;
  61     FELEM *filter_bank;
  62     int filter_length;
  63     int ideal_dst_incr;
  64     int dst_incr;
  65     int index;
  66     int frac;
  67     int src_incr;
  68     int compensation_distance;
  69     int phase_shift;
  70     int phase_mask;
  71     int linear;
  72 }AVResampleContext;
  73
  74 /**
  75  * 0th order modified bessel function of the first kind.
  76  */
  77 static double bessel(double x){
  78     double v=1;
  79     double t=1;
  80     int i;
  81
  82     x= x*x/4;
  83     for(i=1; i<50; i++){
  84         t *= x/(i*i);
  85         v += t;
  86     }
  87     return v;
  88 }
  89
  90 /**
  91  * builds a polyphase filterbank.
  92  * @param factor resampling factor
  93  * @param scale wanted sum of coefficients for each filter
  94  * @param type 0->cubic, 1->blackman nuttall windowed sinc, 2..16->kaiser windowed sinc beta=2..16
  95  */
  96 void av_build_filter(FELEM *filter, double factor, int tap_count, int phase_count, int scale, int type){
  97     int ph, i;
  98     double x, y, w, tab[tap_count];
  99     const int center= (tap_count-1)/2;
 100
 101     /* if upsampling, only need to interpolate, no filter */
 102     if (factor > 1.0)
 103         factor = 1.0;
 104
 105     for(ph=0;ph<phase_count;ph++) {
 106         double norm = 0;
 107         for(i=0;i<tap_count;i++) {
 108             x = M_PI * ((double)(i - center) - (double)ph / phase_count) * factor;
 109             if (x == 0) y = 1.0;
 110             else        y = sin(x) / x;
 111             switch(type){
 112             case 0:{
 113                 const float d= -0.5; //first order derivative = -0.5
 114                 x = fabs(((double)(i - center) - (double)ph / phase_count) * factor);
 115                 if(x<1.0) y= 1 - 3*x*x + 2*x*x*x + d*(            -x*x + x*x*x);
 116                 else      y=                       d*(-4 + 8*x - 5*x*x + x*x*x);
 117                 break;}
 118             case 1:
 119                 w = 2.0*x / (factor*tap_count) + M_PI;
 120                 y *= 0.3635819 - 0.4891775 * cos(w) + 0.1365995 * cos(2*w) - 0.0106411 * cos(3*w);
 121                 break;
 122             default:
 123                 w = 2.0*x / (factor*tap_count*M_PI);
 124                 y *= bessel(type*sqrt(FFMAX(1-w*w, 0)));
 125                 break;
 126             }
 127
 128             tab[i] = y;
 129             norm += y;
 130         }
 131
 132         /* normalize so that an uniform color remains the same */
 133         for(i=0;i<tap_count;i++) {
 134 #ifdef CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE
 135             filter[ph * tap_count + i] = tab[i] / norm;
 136 #else
 137             filter[ph * tap_count + i] = av_clip(lrintf(tab[i] * scale / norm), FELEM_MIN, FELEM_MAX);
 138 #endif
 139         }
 140     }
 141 #if 0
 142     {
 143 #define LEN 1024
 144         int j,k;
 145         double sine[LEN + tap_count];
 146         double filtered[LEN];
 147         double maxff=-2, minff=2, maxsf=-2, minsf=2;
 148         for(i=0; i<LEN; i++){
 149             double ss=0, sf=0, ff=0;
 150             for(j=0; j<LEN+tap_count; j++)
 151                 sine[j]= cos(i*j*M_PI/LEN);
 152             for(j=0; j<LEN; j++){
 153                 double sum=0;
 154                 ph=0;
 155                 for(k=0; k<tap_count; k++)
 156                     sum += filter[ph * tap_count + k] * sine[k+j];
 157                 filtered[j]= sum / (1<<FILTER_SHIFT);
 158                 ss+= sine[j + center] * sine[j + center];
 159                 ff+= filtered[j] * filtered[j];
 160                 sf+= sine[j + center] * filtered[j];
 161             }
 162             ss= sqrt(2*ss/LEN);
 163             ff= sqrt(2*ff/LEN);
 164             sf= 2*sf/LEN;
 165             maxff= FFMAX(maxff, ff);
 166             minff= FFMIN(minff, ff);
 167             maxsf= FFMAX(maxsf, sf);
 168             minsf= FFMIN(minsf, sf);
 169             if(i%11==0){
 170                 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);
 171                 minff=minsf= 2;
 172                 maxff=maxsf= -2;
 173             }
 174         }
 175     }
 176 #endif
 177 }
 178
 179 AVResampleContext *av_resample_init(int out_rate, int in_rate, int filter_size, int phase_shift, int linear, double cutoff){
 180     AVResampleContext *c= av_mallocz(sizeof(AVResampleContext));
 181     double factor= FFMIN(out_rate * cutoff / in_rate, 1.0);
 182     int phase_count= 1<<phase_shift;
 183
 184     c->phase_shift= phase_shift;
 185     c->phase_mask= phase_count-1;
 186     c->linear= linear;
 187
 188     c->filter_length= FFMAX((int)ceil(filter_size/factor), 1);
 189     c->filter_bank= av_mallocz(c->filter_length*(phase_count+1)*sizeof(FELEM));
 190     av_build_filter(c->filter_bank, factor, c->filter_length, phase_count, 1<<FILTER_SHIFT, WINDOW_TYPE);
 191     memcpy(&c->filter_bank[c->filter_length*phase_count+1], c->filter_bank, (c->filter_length-1)*sizeof(FELEM));
 192     c->filter_bank[c->filter_length*phase_count]= c->filter_bank[c->filter_length - 1];
 193
 194     c->src_incr= out_rate;
 195     c->ideal_dst_incr= c->dst_incr= in_rate * phase_count;
 196     c->index= -phase_count*((c->filter_length-1)/2);
 197
 198     return c;
 199 }
 200
 201 void av_resample_close(AVResampleContext *c){
 202     av_freep(&c->filter_bank);
 203     av_freep(&c);
 204 }
 205
 206 void av_resample_compensate(AVResampleContext *c, int sample_delta, int compensation_distance){
 207 //    sample_delta += (c->ideal_dst_incr - c->dst_incr)*(int64_t)c->compensation_distance / c->ideal_dst_incr;
 208     c->compensation_distance= compensation_distance;
 209     c->dst_incr = c->ideal_dst_incr - c->ideal_dst_incr * (int64_t)sample_delta / compensation_distance;
 210 }
 211
 212 int av_resample(AVResampleContext *c, short *dst, short *src, int *consumed, int src_size, int dst_size, int update_ctx){
 213     int dst_index, i;
 214     int index= c->index;
 215     int frac= c->frac;
 216     int dst_incr_frac= c->dst_incr % c->src_incr;
 217     int dst_incr=      c->dst_incr / c->src_incr;
 218     int compensation_distance= c->compensation_distance;
 219
 220   if(compensation_distance == 0 && c->filter_length == 1 && c->phase_shift==0){
 221         int64_t index2= ((int64_t)index)<<32;
 222         int64_t incr= (1LL<<32) * c->dst_incr / c->src_incr;
 223         dst_size= FFMIN(dst_size, (src_size-1-index) * (int64_t)c->src_incr / c->dst_incr);
 224
 225         for(dst_index=0; dst_index < dst_size; dst_index++){
 226             dst[dst_index] = src[index2>>32];
 227             index2 += incr;
 228         }
 229         frac += dst_index * dst_incr_frac;
 230         index += dst_index * dst_incr;
 231         index += frac / c->src_incr;
 232         frac %= c->src_incr;
 233   }else{
 234     for(dst_index=0; dst_index < dst_size; dst_index++){
 235         FELEM *filter= c->filter_bank + c->filter_length*(index & c->phase_mask);
 236         int sample_index= index >> c->phase_shift;
 237         FELEM2 val=0;
 238
 239         if(sample_index < 0){
 240             for(i=0; i<c->filter_length; i++)
 241                 val += src[FFABS(sample_index + i) % src_size] * filter[i];
 242         }else if(sample_index + c->filter_length > src_size){
 243             break;
 244         }else if(c->linear){
 245             FELEM2 v2=0;
 246             for(i=0; i<c->filter_length; i++){
 247                 val += src[sample_index + i] * (FELEM2)filter[i];
 248                 v2  += src[sample_index + i] * (FELEM2)filter[i + c->filter_length];
 249             }
 250             val+=(v2-val)*(FELEML)frac / c->src_incr;
 251         }else{
 252             for(i=0; i<c->filter_length; i++){
 253                 val += src[sample_index + i] * (FELEM2)filter[i];
 254             }
 255         }
 256
 257 #ifdef CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE
 258         dst[dst_index] = av_clip_int16(lrintf(val));
 259 #else
 260         val = (val + (1<<(FILTER_SHIFT-1)))>>FILTER_SHIFT;
 261         dst[dst_index] = (unsigned)(val + 32768) > 65535 ? (val>>31) ^ 32767 : val;
 262 #endif
 263
 264         frac += dst_incr_frac;
 265         index += dst_incr;
 266         if(frac >= c->src_incr){
 267             frac -= c->src_incr;
 268             index++;
 269         }
 270
 271         if(dst_index + 1 == compensation_distance){
 272             compensation_distance= 0;
 273             dst_incr_frac= c->ideal_dst_incr % c->src_incr;
 274             dst_incr=      c->ideal_dst_incr / c->src_incr;
 275         }
 276     }
 277   }
 278     *consumed= FFMAX(index, 0) >> c->phase_shift;
 279     if(index>=0) index &= c->phase_mask;
 280
 281     if(compensation_distance){
 282         compensation_distance -= dst_index;
 283         assert(compensation_distance > 0);
 284     }
 285     if(update_ctx){
 286         c->frac= frac;
 287         c->index= index;
 288         c->dst_incr= dst_incr_frac + c->src_incr*dst_incr;
 289         c->compensation_distance= compensation_distance;
 290     }
 291 #if 0
 292     if(update_ctx && !c->compensation_distance){
 293 #undef rand
 294         av_resample_compensate(c, rand() % (8000*2) - 8000, 8000*2);
 295 av_log(NULL, AV_LOG_DEBUG, "%d %d %d\n", c->dst_incr, c->ideal_dst_incr, c->compensation_distance);
 296     }
 297 #endif
 298
 299     return dst_index;
 300 }