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 FELEM *filter_bank; 00061 int filter_length; 00062 int ideal_dst_incr; 00063 int dst_incr; 00064 int index; 00065 int frac; 00066 int src_incr; 00067 int compensation_distance; 00068 int phase_shift; 00069 int phase_mask; 00070 int linear; 00071 }AVResampleContext; 00072 00076 static double bessel(double x){ 00077 double v=1; 00078 double t=1; 00079 int i; 00080 00081 x= x*x/4; 00082 for(i=1; i<50; i++){ 00083 t *= x/(i*i); 00084 v += t; 00085 } 00086 return v; 00087 } 00088 00095 void av_build_filter(FELEM *filter, double factor, int tap_count, int phase_count, int scale, int type){ 00096 int ph, i; 00097 double x, y, w, tab[tap_count]; 00098 const int center= (tap_count-1)/2; 00099 00100 /* if upsampling, only need to interpolate, no filter */ 00101 if (factor > 1.0) 00102 factor = 1.0; 00103 00104 for(ph=0;ph<phase_count;ph++) { 00105 double norm = 0; 00106 for(i=0;i<tap_count;i++) { 00107 x = M_PI * ((double)(i - center) - (double)ph / phase_count) * factor; 00108 if (x == 0) y = 1.0; 00109 else y = sin(x) / x; 00110 switch(type){ 00111 case 0:{ 00112 const float d= -0.5; //first order derivative = -0.5 00113 x = fabs(((double)(i - center) - (double)ph / phase_count) * factor); 00114 if(x<1.0) y= 1 - 3*x*x + 2*x*x*x + d*( -x*x + x*x*x); 00115 else y= d*(-4 + 8*x - 5*x*x + x*x*x); 00116 break;} 00117 case 1: 00118 w = 2.0*x / (factor*tap_count) + M_PI; 00119 y *= 0.3635819 - 0.4891775 * cos(w) + 0.1365995 * cos(2*w) - 0.0106411 * cos(3*w); 00120 break; 00121 default: 00122 w = 2.0*x / (factor*tap_count*M_PI); 00123 y *= bessel(type*sqrt(FFMAX(1-w*w, 0))); 00124 break; 00125 } 00126 00127 tab[i] = y; 00128 norm += y; 00129 } 00130 00131 /* normalize so that an uniform color remains the same */ 00132 for(i=0;i<tap_count;i++) { 00133 #ifdef CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE 00134 filter[ph * tap_count + i] = tab[i] / norm; 00135 #else 00136 filter[ph * tap_count + i] = av_clip(lrintf(tab[i] * scale / norm), FELEM_MIN, FELEM_MAX); 00137 #endif 00138 } 00139 } 00140 #if 0 00141 { 00142 #define LEN 1024 00143 int j,k; 00144 double sine[LEN + tap_count]; 00145 double filtered[LEN]; 00146 double maxff=-2, minff=2, maxsf=-2, minsf=2; 00147 for(i=0; i<LEN; i++){ 00148 double ss=0, sf=0, ff=0; 00149 for(j=0; j<LEN+tap_count; j++) 00150 sine[j]= cos(i*j*M_PI/LEN); 00151 for(j=0; j<LEN; j++){ 00152 double sum=0; 00153 ph=0; 00154 for(k=0; k<tap_count; k++) 00155 sum += filter[ph * tap_count + k] * sine[k+j]; 00156 filtered[j]= sum / (1<<FILTER_SHIFT); 00157 ss+= sine[j + center] * sine[j + center]; 00158 ff+= filtered[j] * filtered[j]; 00159 sf+= sine[j + center] * filtered[j]; 00160 } 00161 ss= sqrt(2*ss/LEN); 00162 ff= sqrt(2*ff/LEN); 00163 sf= 2*sf/LEN; 00164 maxff= FFMAX(maxff, ff); 00165 minff= FFMIN(minff, ff); 00166 maxsf= FFMAX(maxsf, sf); 00167 minsf= FFMIN(minsf, sf); 00168 if(i%11==0){ 00169 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); 00170 minff=minsf= 2; 00171 maxff=maxsf= -2; 00172 } 00173 } 00174 } 00175 #endif 00176 } 00177 00178 AVResampleContext *av_resample_init(int out_rate, int in_rate, int filter_size, int phase_shift, int linear, double cutoff){ 00179 AVResampleContext *c= av_mallocz(sizeof(AVResampleContext)); 00180 double factor= FFMIN(out_rate * cutoff / in_rate, 1.0); 00181 int phase_count= 1<<phase_shift; 00182 00183 c->phase_shift= phase_shift; 00184 c->phase_mask= phase_count-1; 00185 c->linear= linear; 00186 00187 c->filter_length= FFMAX((int)ceil(filter_size/factor), 1); 00188 c->filter_bank= av_mallocz(c->filter_length*(phase_count+1)*sizeof(FELEM)); 00189 av_build_filter(c->filter_bank, factor, c->filter_length, phase_count, 1<<FILTER_SHIFT, WINDOW_TYPE); 00190 memcpy(&c->filter_bank[c->filter_length*phase_count+1], c->filter_bank, (c->filter_length-1)*sizeof(FELEM)); 00191 c->filter_bank[c->filter_length*phase_count]= c->filter_bank[c->filter_length - 1]; 00192 00193 if(!av_reduce(&c->src_incr, &c->dst_incr, out_rate, in_rate * (int64_t)phase_count, INT32_MAX/2)) 00194 return NULL; 00195 c->ideal_dst_incr= c->dst_incr; 00196 00197 c->index= -phase_count*((c->filter_length-1)/2); 00198 00199 return c; 00200 } 00201 00202 void av_resample_close(AVResampleContext *c){ 00203 av_freep(&c->filter_bank); 00204 av_freep(&c); 00205 } 00206 00207 void av_resample_compensate(AVResampleContext *c, int sample_delta, int compensation_distance){ 00208 // sample_delta += (c->ideal_dst_incr - c->dst_incr)*(int64_t)c->compensation_distance / c->ideal_dst_incr; 00209 c->compensation_distance= compensation_distance; 00210 c->dst_incr = c->ideal_dst_incr - c->ideal_dst_incr * (int64_t)sample_delta / compensation_distance; 00211 } 00212 00213 int av_resample(AVResampleContext *c, short *dst, short *src, int *consumed, int src_size, int dst_size, int update_ctx){ 00214 int dst_index, i; 00215 int index= c->index; 00216 int frac= c->frac; 00217 int dst_incr_frac= c->dst_incr % c->src_incr; 00218 int dst_incr= c->dst_incr / c->src_incr; 00219 int compensation_distance= c->compensation_distance; 00220 00221 if(compensation_distance == 0 && c->filter_length == 1 && c->phase_shift==0){ 00222 int64_t index2= ((int64_t)index)<<32; 00223 int64_t incr= (1LL<<32) * c->dst_incr / c->src_incr; 00224 dst_size= FFMIN(dst_size, (src_size-1-index) * (int64_t)c->src_incr / c->dst_incr); 00225 00226 for(dst_index=0; dst_index < dst_size; dst_index++){ 00227 dst[dst_index] = src[index2>>32]; 00228 index2 += incr; 00229 } 00230 index += dst_index * dst_incr; 00231 index += (frac + dst_index * (int64_t)dst_incr_frac) / c->src_incr; 00232 frac = (frac + dst_index * (int64_t)dst_incr_frac) % c->src_incr; 00233 }else{ 00234 for(dst_index=0; dst_index < dst_size; dst_index++){ 00235 FELEM *filter= c->filter_bank + c->filter_length*(index & c->phase_mask); 00236 int sample_index= index >> c->phase_shift; 00237 FELEM2 val=0; 00238 00239 if(sample_index < 0){ 00240 for(i=0; i<c->filter_length; i++) 00241 val += src[FFABS(sample_index + i) % src_size] * filter[i]; 00242 }else if(sample_index + c->filter_length > src_size){ 00243 break; 00244 }else if(c->linear){ 00245 FELEM2 v2=0; 00246 for(i=0; i<c->filter_length; i++){ 00247 val += src[sample_index + i] * (FELEM2)filter[i]; 00248 v2 += src[sample_index + i] * (FELEM2)filter[i + c->filter_length]; 00249 } 00250 val+=(v2-val)*(FELEML)frac / c->src_incr; 00251 }else{ 00252 for(i=0; i<c->filter_length; i++){ 00253 val += src[sample_index + i] * (FELEM2)filter[i]; 00254 } 00255 } 00256 00257 #ifdef CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE 00258 dst[dst_index] = av_clip_int16(lrintf(val)); 00259 #else 00260 val = (val + (1<<(FILTER_SHIFT-1)))>>FILTER_SHIFT; 00261 dst[dst_index] = (unsigned)(val + 32768) > 65535 ? (val>>31) ^ 32767 : val; 00262 #endif 00263 00264 frac += dst_incr_frac; 00265 index += dst_incr; 00266 if(frac >= c->src_incr){ 00267 frac -= c->src_incr; 00268 index++; 00269 } 00270 00271 if(dst_index + 1 == compensation_distance){ 00272 compensation_distance= 0; 00273 dst_incr_frac= c->ideal_dst_incr % c->src_incr; 00274 dst_incr= c->ideal_dst_incr / c->src_incr; 00275 } 00276 } 00277 } 00278 *consumed= FFMAX(index, 0) >> c->phase_shift; 00279 if(index>=0) index &= c->phase_mask; 00280 00281 if(compensation_distance){ 00282 compensation_distance -= dst_index; 00283 assert(compensation_distance > 0); 00284 } 00285 if(update_ctx){ 00286 c->frac= frac; 00287 c->index= index; 00288 c->dst_incr= dst_incr_frac + c->src_incr*dst_incr; 00289 c->compensation_distance= compensation_distance; 00290 } 00291 #if 0 00292 if(update_ctx && !c->compensation_distance){ 00293 #undef rand 00294 av_resample_compensate(c, rand() % (8000*2) - 8000, 8000*2); 00295 av_log(NULL, AV_LOG_DEBUG, "%d %d %d\n", c->dst_incr, c->ideal_dst_incr, c->compensation_distance); 00296 } 00297 #endif 00298 00299 return dst_index; 00300 }