libavcodec/resample2.c

   1 /*
   2  * audio resampling
   3  * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav 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  * Libav 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 Libav; 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 "avcodec.h"
  29 #include "dsputil.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(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(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     c->src_incr= out_rate;
 214     c->ideal_dst_incr= c->dst_incr= in_rate * phase_count;
 215     c->index= -phase_count*((c->filter_length-1)/2);
 216
 217     return c;
 218 error:
 219     av_free(c->filter_bank);
 220     av_free(c);
 221     return NULL;
 222 }
 223
 224 void av_resample_close(AVResampleContext *c){
 225     av_freep(&c->filter_bank);
 226     av_freep(&c);
 227 }
 228
 229 void av_resample_compensate(AVResampleContext *c, int sample_delta, int compensation_distance){
 230 //    sample_delta += (c->ideal_dst_incr - c->dst_incr)*(int64_t)c->compensation_distance / c->ideal_dst_incr;
 231     c->compensation_distance= compensation_distance;
 232     c->dst_incr = c->ideal_dst_incr - c->ideal_dst_incr * (int64_t)sample_delta / compensation_distance;
 233 }
 234
 235 int av_resample(AVResampleContext *c, short *dst, short *src, int *consumed, int src_size, int dst_size, int update_ctx){
 236     int dst_index, i;
 237     int index= c->index;
 238     int frac= c->frac;
 239     int dst_incr_frac= c->dst_incr % c->src_incr;
 240     int dst_incr=      c->dst_incr / c->src_incr;
 241     int compensation_distance= c->compensation_distance;
 242
 243   if(compensation_distance == 0 && c->filter_length == 1 && c->phase_shift==0){
 244         int64_t index2= ((int64_t)index)<<32;
 245         int64_t incr= (1LL<<32) * c->dst_incr / c->src_incr;
 246         dst_size= FFMIN(dst_size, (src_size-1-index) * (int64_t)c->src_incr / c->dst_incr);
 247
 248         for(dst_index=0; dst_index < dst_size; dst_index++){
 249             dst[dst_index] = src[index2>>32];
 250             index2 += incr;
 251         }
 252         frac += dst_index * dst_incr_frac;
 253         index += dst_index * dst_incr;
 254         index += frac / c->src_incr;
 255         frac %= c->src_incr;
 256   }else{
 257     for(dst_index=0; dst_index < dst_size; dst_index++){
 258         FELEM *filter= c->filter_bank + c->filter_length*(index & c->phase_mask);
 259         int sample_index= index >> c->phase_shift;
 260         FELEM2 val=0;
 261
 262         if(sample_index < 0){
 263             for(i=0; i<c->filter_length; i++)
 264                 val += src[FFABS(sample_index + i) % src_size] * filter[i];
 265         }else if(sample_index + c->filter_length > src_size){
 266             break;
 267         }else if(c->linear){
 268             FELEM2 v2=0;
 269             for(i=0; i<c->filter_length; i++){
 270                 val += src[sample_index + i] * (FELEM2)filter[i];
 271                 v2  += src[sample_index + i] * (FELEM2)filter[i + c->filter_length];
 272             }
 273             val+=(v2-val)*(FELEML)frac / c->src_incr;
 274         }else{
 275             for(i=0; i<c->filter_length; i++){
 276                 val += src[sample_index + i] * (FELEM2)filter[i];
 277             }
 278         }
 279
 280 #ifdef CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE
 281         dst[dst_index] = av_clip_int16(lrintf(val));
 282 #else
 283         val = (val + (1<<(FILTER_SHIFT-1)))>>FILTER_SHIFT;
 284         dst[dst_index] = (unsigned)(val + 32768) > 65535 ? (val>>31) ^ 32767 : val;
 285 #endif
 286
 287         frac += dst_incr_frac;
 288         index += dst_incr;
 289         if(frac >= c->src_incr){
 290             frac -= c->src_incr;
 291             index++;
 292         }
 293
 294         if(dst_index + 1 == compensation_distance){
 295             compensation_distance= 0;
 296             dst_incr_frac= c->ideal_dst_incr % c->src_incr;
 297             dst_incr=      c->ideal_dst_incr / c->src_incr;
 298         }
 299     }
 300   }
 301     *consumed= FFMAX(index, 0) >> c->phase_shift;
 302     if(index>=0) index &= c->phase_mask;
 303
 304     if(compensation_distance){
 305         compensation_distance -= dst_index;
 306         assert(compensation_distance > 0);
 307     }
 308     if(update_ctx){
 309         c->frac= frac;
 310         c->index= index;
 311         c->dst_incr= dst_incr_frac + c->src_incr*dst_incr;
 312         c->compensation_distance= compensation_distance;
 313     }
 314 #if 0
 315     if(update_ctx && !c->compensation_distance){
 316 #undef rand
 317         av_resample_compensate(c, rand() % (8000*2) - 8000, 8000*2);
 318 av_log(NULL, AV_LOG_DEBUG, "%d %d %d\n", c->dst_incr, c->ideal_dst_incr, c->compensation_distance);
 319     }
 320 #endif
 321
 322     return dst_index;
 323 }
 324
 325 #endif