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libavcodec/resample2.c

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00001 /*
00002  * audio resampling
00003  * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00028 #include "avcodec.h"
00029 #include "dsputil.h"
00030 
00031 #ifndef CONFIG_RESAMPLE_HP
00032 #define FILTER_SHIFT 15
00033 
00034 #define FELEM int16_t
00035 #define FELEM2 int32_t
00036 #define FELEML int64_t
00037 #define FELEM_MAX INT16_MAX
00038 #define FELEM_MIN INT16_MIN
00039 #define WINDOW_TYPE 9
00040 #elif !defined(CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE)
00041 #define FILTER_SHIFT 30
00042 
00043 #define FELEM int32_t
00044 #define FELEM2 int64_t
00045 #define FELEML int64_t
00046 #define FELEM_MAX INT32_MAX
00047 #define FELEM_MIN INT32_MIN
00048 #define WINDOW_TYPE 12
00049 #else
00050 #define FILTER_SHIFT 0
00051 
00052 #define FELEM double
00053 #define FELEM2 double
00054 #define FELEML double
00055 #define WINDOW_TYPE 24
00056 #endif
00057 
00058 
00059 typedef struct AVResampleContext{
00060     const AVClass *av_class;
00061     FELEM *filter_bank;
00062     int filter_length;
00063     int ideal_dst_incr;
00064     int dst_incr;
00065     int index;
00066     int frac;
00067     int src_incr;
00068     int compensation_distance;
00069     int phase_shift;
00070     int phase_mask;
00071     int linear;
00072 }AVResampleContext;
00073 
00077 static double bessel(double x){
00078     double v=1;
00079     double lastv=0;
00080     double t=1;
00081     int i;
00082 
00083     x= x*x/4;
00084     for(i=1; v != lastv; i++){
00085         lastv=v;
00086         t *= x/(i*i);
00087         v += t;
00088     }
00089     return v;
00090 }
00091 
00098 static void build_filter(FELEM *filter, double factor, int tap_count, int phase_count, int scale, int type){
00099     int ph, i;
00100     double x, y, w, tab[tap_count];
00101     const int center= (tap_count-1)/2;
00102 
00103     /* if upsampling, only need to interpolate, no filter */
00104     if (factor > 1.0)
00105         factor = 1.0;
00106 
00107     for(ph=0;ph<phase_count;ph++) {
00108         double norm = 0;
00109         for(i=0;i<tap_count;i++) {
00110             x = M_PI * ((double)(i - center) - (double)ph / phase_count) * factor;
00111             if (x == 0) y = 1.0;
00112             else        y = sin(x) / x;
00113             switch(type){
00114             case 0:{
00115                 const float d= -0.5; //first order derivative = -0.5
00116                 x = fabs(((double)(i - center) - (double)ph / phase_count) * factor);
00117                 if(x<1.0) y= 1 - 3*x*x + 2*x*x*x + d*(            -x*x + x*x*x);
00118                 else      y=                       d*(-4 + 8*x - 5*x*x + x*x*x);
00119                 break;}
00120             case 1:
00121                 w = 2.0*x / (factor*tap_count) + M_PI;
00122                 y *= 0.3635819 - 0.4891775 * cos(w) + 0.1365995 * cos(2*w) - 0.0106411 * cos(3*w);
00123                 break;
00124             default:
00125                 w = 2.0*x / (factor*tap_count*M_PI);
00126                 y *= bessel(type*sqrt(FFMAX(1-w*w, 0)));
00127                 break;
00128             }
00129 
00130             tab[i] = y;
00131             norm += y;
00132         }
00133 
00134         /* normalize so that an uniform color remains the same */
00135         for(i=0;i<tap_count;i++) {
00136 #ifdef CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE
00137             filter[ph * tap_count + i] = tab[i] / norm;
00138 #else
00139             filter[ph * tap_count + i] = av_clip(lrintf(tab[i] * scale / norm), FELEM_MIN, FELEM_MAX);
00140 #endif
00141         }
00142     }
00143 #if 0
00144     {
00145 #define LEN 1024
00146         int j,k;
00147         double sine[LEN + tap_count];
00148         double filtered[LEN];
00149         double maxff=-2, minff=2, maxsf=-2, minsf=2;
00150         for(i=0; i<LEN; i++){
00151             double ss=0, sf=0, ff=0;
00152             for(j=0; j<LEN+tap_count; j++)
00153                 sine[j]= cos(i*j*M_PI/LEN);
00154             for(j=0; j<LEN; j++){
00155                 double sum=0;
00156                 ph=0;
00157                 for(k=0; k<tap_count; k++)
00158                     sum += filter[ph * tap_count + k] * sine[k+j];
00159                 filtered[j]= sum / (1<<FILTER_SHIFT);
00160                 ss+= sine[j + center] * sine[j + center];
00161                 ff+= filtered[j] * filtered[j];
00162                 sf+= sine[j + center] * filtered[j];
00163             }
00164             ss= sqrt(2*ss/LEN);
00165             ff= sqrt(2*ff/LEN);
00166             sf= 2*sf/LEN;
00167             maxff= FFMAX(maxff, ff);
00168             minff= FFMIN(minff, ff);
00169             maxsf= FFMAX(maxsf, sf);
00170             minsf= FFMIN(minsf, sf);
00171             if(i%11==0){
00172                 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);
00173                 minff=minsf= 2;
00174                 maxff=maxsf= -2;
00175             }
00176         }
00177     }
00178 #endif
00179 }
00180 
00181 AVResampleContext *av_resample_init(int out_rate, int in_rate, int filter_size, int phase_shift, int linear, double cutoff){
00182     AVResampleContext *c= av_mallocz(sizeof(AVResampleContext));
00183     double factor= FFMIN(out_rate * cutoff / in_rate, 1.0);
00184     int phase_count= 1<<phase_shift;
00185 
00186     c->phase_shift= phase_shift;
00187     c->phase_mask= phase_count-1;
00188     c->linear= linear;
00189 
00190     c->filter_length= FFMAX((int)ceil(filter_size/factor), 1);
00191     c->filter_bank= av_mallocz(c->filter_length*(phase_count+1)*sizeof(FELEM));
00192     build_filter(c->filter_bank, factor, c->filter_length, phase_count, 1<<FILTER_SHIFT, WINDOW_TYPE);
00193     memcpy(&c->filter_bank[c->filter_length*phase_count+1], c->filter_bank, (c->filter_length-1)*sizeof(FELEM));
00194     c->filter_bank[c->filter_length*phase_count]= c->filter_bank[c->filter_length - 1];
00195 
00196     c->src_incr= out_rate;
00197     c->ideal_dst_incr= c->dst_incr= in_rate * phase_count;
00198     c->index= -phase_count*((c->filter_length-1)/2);
00199 
00200     return c;
00201 }
00202 
00203 void av_resample_close(AVResampleContext *c){
00204     av_freep(&c->filter_bank);
00205     av_freep(&c);
00206 }
00207 
00208 void av_resample_compensate(AVResampleContext *c, int sample_delta, int compensation_distance){
00209 //    sample_delta += (c->ideal_dst_incr - c->dst_incr)*(int64_t)c->compensation_distance / c->ideal_dst_incr;
00210     c->compensation_distance= compensation_distance;
00211     c->dst_incr = c->ideal_dst_incr - c->ideal_dst_incr * (int64_t)sample_delta / compensation_distance;
00212 }
00213 
00214 int av_resample(AVResampleContext *c, short *dst, short *src, int *consumed, int src_size, int dst_size, int update_ctx){
00215     int dst_index, i;
00216     int index= c->index;
00217     int frac= c->frac;
00218     int dst_incr_frac= c->dst_incr % c->src_incr;
00219     int dst_incr=      c->dst_incr / c->src_incr;
00220     int compensation_distance= c->compensation_distance;
00221 
00222   if(compensation_distance == 0 && c->filter_length == 1 && c->phase_shift==0){
00223         int64_t index2= ((int64_t)index)<<32;
00224         int64_t incr= (1LL<<32) * c->dst_incr / c->src_incr;
00225         dst_size= FFMIN(dst_size, (src_size-1-index) * (int64_t)c->src_incr / c->dst_incr);
00226 
00227         for(dst_index=0; dst_index < dst_size; dst_index++){
00228             dst[dst_index] = src[index2>>32];
00229             index2 += incr;
00230         }
00231         frac += dst_index * dst_incr_frac;
00232         index += dst_index * dst_incr;
00233         index += frac / c->src_incr;
00234         frac %= c->src_incr;
00235   }else{
00236     for(dst_index=0; dst_index < dst_size; dst_index++){
00237         FELEM *filter= c->filter_bank + c->filter_length*(index & c->phase_mask);
00238         int sample_index= index >> c->phase_shift;
00239         FELEM2 val=0;
00240 
00241         if(sample_index < 0){
00242             for(i=0; i<c->filter_length; i++)
00243                 val += src[FFABS(sample_index + i) % src_size] * filter[i];
00244         }else if(sample_index + c->filter_length > src_size){
00245             break;
00246         }else if(c->linear){
00247             FELEM2 v2=0;
00248             for(i=0; i<c->filter_length; i++){
00249                 val += src[sample_index + i] * (FELEM2)filter[i];
00250                 v2  += src[sample_index + i] * (FELEM2)filter[i + c->filter_length];
00251             }
00252             val+=(v2-val)*(FELEML)frac / c->src_incr;
00253         }else{
00254             for(i=0; i<c->filter_length; i++){
00255                 val += src[sample_index + i] * (FELEM2)filter[i];
00256             }
00257         }
00258 
00259 #ifdef CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE
00260         dst[dst_index] = av_clip_int16(lrintf(val));
00261 #else
00262         val = (val + (1<<(FILTER_SHIFT-1)))>>FILTER_SHIFT;
00263         dst[dst_index] = (unsigned)(val + 32768) > 65535 ? (val>>31) ^ 32767 : val;
00264 #endif
00265 
00266         frac += dst_incr_frac;
00267         index += dst_incr;
00268         if(frac >= c->src_incr){
00269             frac -= c->src_incr;
00270             index++;
00271         }
00272 
00273         if(dst_index + 1 == compensation_distance){
00274             compensation_distance= 0;
00275             dst_incr_frac= c->ideal_dst_incr % c->src_incr;
00276             dst_incr=      c->ideal_dst_incr / c->src_incr;
00277         }
00278     }
00279   }
00280     *consumed= FFMAX(index, 0) >> c->phase_shift;
00281     if(index>=0) index &= c->phase_mask;
00282 
00283     if(compensation_distance){
00284         compensation_distance -= dst_index;
00285         assert(compensation_distance > 0);
00286     }
00287     if(update_ctx){
00288         c->frac= frac;
00289         c->index= index;
00290         c->dst_incr= dst_incr_frac + c->src_incr*dst_incr;
00291         c->compensation_distance= compensation_distance;
00292     }
00293 #if 0
00294     if(update_ctx && !c->compensation_distance){
00295 #undef rand
00296         av_resample_compensate(c, rand() % (8000*2) - 8000, 8000*2);
00297 av_log(NULL, AV_LOG_DEBUG, "%d %d %d\n", c->dst_incr, c->ideal_dst_incr, c->compensation_distance);
00298     }
00299 #endif
00300 
00301     return dst_index;
00302 }

Generated on Fri Sep 16 2011 17:17:42 for FFmpeg by  doxygen 1.7.1