Libav
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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 }