yading@10: /*
yading@10:  * audio resampling
yading@10:  * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: /**
yading@10:  * @file
yading@10:  * audio resampling
yading@10:  * @author Michael Niedermayer <michaelni@gmx.at>
yading@10:  */
yading@10: 
yading@10: #include "libavutil/avassert.h"
yading@10: #include "avcodec.h"
yading@10: #include "libavutil/common.h"
yading@10: 
yading@10: #if FF_API_AVCODEC_RESAMPLE
yading@10: 
yading@10: #ifndef CONFIG_RESAMPLE_HP
yading@10: #define FILTER_SHIFT 15
yading@10: 
yading@10: #define FELEM int16_t
yading@10: #define FELEM2 int32_t
yading@10: #define FELEML int64_t
yading@10: #define FELEM_MAX INT16_MAX
yading@10: #define FELEM_MIN INT16_MIN
yading@10: #define WINDOW_TYPE 9
yading@10: #elif !defined(CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE)
yading@10: #define FILTER_SHIFT 30
yading@10: 
yading@10: #define FELEM int32_t
yading@10: #define FELEM2 int64_t
yading@10: #define FELEML int64_t
yading@10: #define FELEM_MAX INT32_MAX
yading@10: #define FELEM_MIN INT32_MIN
yading@10: #define WINDOW_TYPE 12
yading@10: #else
yading@10: #define FILTER_SHIFT 0
yading@10: 
yading@10: #define FELEM double
yading@10: #define FELEM2 double
yading@10: #define FELEML double
yading@10: #define WINDOW_TYPE 24
yading@10: #endif
yading@10: 
yading@10: 
yading@10: typedef struct AVResampleContext{
yading@10:     const AVClass *av_class;
yading@10:     FELEM *filter_bank;
yading@10:     int filter_length;
yading@10:     int ideal_dst_incr;
yading@10:     int dst_incr;
yading@10:     int index;
yading@10:     int frac;
yading@10:     int src_incr;
yading@10:     int compensation_distance;
yading@10:     int phase_shift;
yading@10:     int phase_mask;
yading@10:     int linear;
yading@10: }AVResampleContext;
yading@10: 
yading@10: /**
yading@10:  * 0th order modified bessel function of the first kind.
yading@10:  */
yading@10: static double bessel(double x){
yading@10:     double v=1;
yading@10:     double lastv=0;
yading@10:     double t=1;
yading@10:     int i;
yading@10: 
yading@10:     x= x*x/4;
yading@10:     for(i=1; v != lastv; i++){
yading@10:         lastv=v;
yading@10:         t *= x/(i*i);
yading@10:         v += t;
yading@10:     }
yading@10:     return v;
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Build a polyphase filterbank.
yading@10:  * @param factor resampling factor
yading@10:  * @param scale wanted sum of coefficients for each filter
yading@10:  * @param type 0->cubic, 1->blackman nuttall windowed sinc, 2..16->kaiser windowed sinc beta=2..16
yading@10:  * @return 0 on success, negative on error
yading@10:  */
yading@10: static int build_filter(FELEM *filter, double factor, int tap_count, int phase_count, int scale, int type){
yading@10:     int ph, i;
yading@10:     double x, y, w;
yading@10:     double *tab = av_malloc(tap_count * sizeof(*tab));
yading@10:     const int center= (tap_count-1)/2;
yading@10: 
yading@10:     if (!tab)
yading@10:         return AVERROR(ENOMEM);
yading@10: 
yading@10:     /* if upsampling, only need to interpolate, no filter */
yading@10:     if (factor > 1.0)
yading@10:         factor = 1.0;
yading@10: 
yading@10:     for(ph=0;ph<phase_count;ph++) {
yading@10:         double norm = 0;
yading@10:         for(i=0;i<tap_count;i++) {
yading@10:             x = M_PI * ((double)(i - center) - (double)ph / phase_count) * factor;
yading@10:             if (x == 0) y = 1.0;
yading@10:             else        y = sin(x) / x;
yading@10:             switch(type){
yading@10:             case 0:{
yading@10:                 const float d= -0.5; //first order derivative = -0.5
yading@10:                 x = fabs(((double)(i - center) - (double)ph / phase_count) * factor);
yading@10:                 if(x<1.0) y= 1 - 3*x*x + 2*x*x*x + d*(            -x*x + x*x*x);
yading@10:                 else      y=                       d*(-4 + 8*x - 5*x*x + x*x*x);
yading@10:                 break;}
yading@10:             case 1:
yading@10:                 w = 2.0*x / (factor*tap_count) + M_PI;
yading@10:                 y *= 0.3635819 - 0.4891775 * cos(w) + 0.1365995 * cos(2*w) - 0.0106411 * cos(3*w);
yading@10:                 break;
yading@10:             default:
yading@10:                 w = 2.0*x / (factor*tap_count*M_PI);
yading@10:                 y *= bessel(type*sqrt(FFMAX(1-w*w, 0)));
yading@10:                 break;
yading@10:             }
yading@10: 
yading@10:             tab[i] = y;
yading@10:             norm += y;
yading@10:         }
yading@10: 
yading@10:         /* normalize so that an uniform color remains the same */
yading@10:         for(i=0;i<tap_count;i++) {
yading@10: #ifdef CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE
yading@10:             filter[ph * tap_count + i] = tab[i] / norm;
yading@10: #else
yading@10:             filter[ph * tap_count + i] = av_clip(lrintf(tab[i] * scale / norm), FELEM_MIN, FELEM_MAX);
yading@10: #endif
yading@10:         }
yading@10:     }
yading@10: #if 0
yading@10:     {
yading@10: #define LEN 1024
yading@10:         int j,k;
yading@10:         double sine[LEN + tap_count];
yading@10:         double filtered[LEN];
yading@10:         double maxff=-2, minff=2, maxsf=-2, minsf=2;
yading@10:         for(i=0; i<LEN; i++){
yading@10:             double ss=0, sf=0, ff=0;
yading@10:             for(j=0; j<LEN+tap_count; j++)
yading@10:                 sine[j]= cos(i*j*M_PI/LEN);
yading@10:             for(j=0; j<LEN; j++){
yading@10:                 double sum=0;
yading@10:                 ph=0;
yading@10:                 for(k=0; k<tap_count; k++)
yading@10:                     sum += filter[ph * tap_count + k] * sine[k+j];
yading@10:                 filtered[j]= sum / (1<<FILTER_SHIFT);
yading@10:                 ss+= sine[j + center] * sine[j + center];
yading@10:                 ff+= filtered[j] * filtered[j];
yading@10:                 sf+= sine[j + center] * filtered[j];
yading@10:             }
yading@10:             ss= sqrt(2*ss/LEN);
yading@10:             ff= sqrt(2*ff/LEN);
yading@10:             sf= 2*sf/LEN;
yading@10:             maxff= FFMAX(maxff, ff);
yading@10:             minff= FFMIN(minff, ff);
yading@10:             maxsf= FFMAX(maxsf, sf);
yading@10:             minsf= FFMIN(minsf, sf);
yading@10:             if(i%11==0){
yading@10:                 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);
yading@10:                 minff=minsf= 2;
yading@10:                 maxff=maxsf= -2;
yading@10:             }
yading@10:         }
yading@10:     }
yading@10: #endif
yading@10: 
yading@10:     av_free(tab);
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: AVResampleContext *av_resample_init(int out_rate, int in_rate, int filter_size, int phase_shift, int linear, double cutoff){
yading@10:     AVResampleContext *c= av_mallocz(sizeof(AVResampleContext));
yading@10:     double factor= FFMIN(out_rate * cutoff / in_rate, 1.0);
yading@10:     int phase_count= 1<<phase_shift;
yading@10: 
yading@10:     if (!c)
yading@10:         return NULL;
yading@10: 
yading@10:     c->phase_shift= phase_shift;
yading@10:     c->phase_mask= phase_count-1;
yading@10:     c->linear= linear;
yading@10: 
yading@10:     c->filter_length= FFMAX((int)ceil(filter_size/factor), 1);
yading@10:     c->filter_bank= av_mallocz(c->filter_length*(phase_count+1)*sizeof(FELEM));
yading@10:     if (!c->filter_bank)
yading@10:         goto error;
yading@10:     if (build_filter(c->filter_bank, factor, c->filter_length, phase_count, 1<<FILTER_SHIFT, WINDOW_TYPE))
yading@10:         goto error;
yading@10:     memcpy(&c->filter_bank[c->filter_length*phase_count+1], c->filter_bank, (c->filter_length-1)*sizeof(FELEM));
yading@10:     c->filter_bank[c->filter_length*phase_count]= c->filter_bank[c->filter_length - 1];
yading@10: 
yading@10:     if(!av_reduce(&c->src_incr, &c->dst_incr, out_rate, in_rate * (int64_t)phase_count, INT32_MAX/2))
yading@10:         goto error;
yading@10:     c->ideal_dst_incr= c->dst_incr;
yading@10: 
yading@10:     c->index= -phase_count*((c->filter_length-1)/2);
yading@10: 
yading@10:     return c;
yading@10: error:
yading@10:     av_free(c->filter_bank);
yading@10:     av_free(c);
yading@10:     return NULL;
yading@10: }
yading@10: 
yading@10: void av_resample_close(AVResampleContext *c){
yading@10:     av_freep(&c->filter_bank);
yading@10:     av_freep(&c);
yading@10: }
yading@10: 
yading@10: void av_resample_compensate(AVResampleContext *c, int sample_delta, int compensation_distance){
yading@10: //    sample_delta += (c->ideal_dst_incr - c->dst_incr)*(int64_t)c->compensation_distance / c->ideal_dst_incr;
yading@10:     c->compensation_distance= compensation_distance;
yading@10:     c->dst_incr = c->ideal_dst_incr - c->ideal_dst_incr * (int64_t)sample_delta / compensation_distance;
yading@10: }
yading@10: 
yading@10: int av_resample(AVResampleContext *c, short *dst, short *src, int *consumed, int src_size, int dst_size, int update_ctx){
yading@10:     int dst_index, i;
yading@10:     int index= c->index;
yading@10:     int frac= c->frac;
yading@10:     int dst_incr_frac= c->dst_incr % c->src_incr;
yading@10:     int dst_incr=      c->dst_incr / c->src_incr;
yading@10:     int compensation_distance= c->compensation_distance;
yading@10: 
yading@10:   if(compensation_distance == 0 && c->filter_length == 1 && c->phase_shift==0){
yading@10:         int64_t index2= ((int64_t)index)<<32;
yading@10:         int64_t incr= (1LL<<32) * c->dst_incr / c->src_incr;
yading@10:         dst_size= FFMIN(dst_size, (src_size-1-index) * (int64_t)c->src_incr / c->dst_incr);
yading@10: 
yading@10:         for(dst_index=0; dst_index < dst_size; dst_index++){
yading@10:             dst[dst_index] = src[index2>>32];
yading@10:             index2 += incr;
yading@10:         }
yading@10:         index += dst_index * dst_incr;
yading@10:         index += (frac + dst_index * (int64_t)dst_incr_frac) / c->src_incr;
yading@10:         frac   = (frac + dst_index * (int64_t)dst_incr_frac) % c->src_incr;
yading@10:   }else{
yading@10:     for(dst_index=0; dst_index < dst_size; dst_index++){
yading@10:         FELEM *filter= c->filter_bank + c->filter_length*(index & c->phase_mask);
yading@10:         int sample_index= index >> c->phase_shift;
yading@10:         FELEM2 val=0;
yading@10: 
yading@10:         if(sample_index < 0){
yading@10:             for(i=0; i<c->filter_length; i++)
yading@10:                 val += src[FFABS(sample_index + i) % src_size] * filter[i];
yading@10:         }else if(sample_index + c->filter_length > src_size){
yading@10:             break;
yading@10:         }else if(c->linear){
yading@10:             FELEM2 v2=0;
yading@10:             for(i=0; i<c->filter_length; i++){
yading@10:                 val += src[sample_index + i] * (FELEM2)filter[i];
yading@10:                 v2  += src[sample_index + i] * (FELEM2)filter[i + c->filter_length];
yading@10:             }
yading@10:             val+=(v2-val)*(FELEML)frac / c->src_incr;
yading@10:         }else{
yading@10:             for(i=0; i<c->filter_length; i++){
yading@10:                 val += src[sample_index + i] * (FELEM2)filter[i];
yading@10:             }
yading@10:         }
yading@10: 
yading@10: #ifdef CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE
yading@10:         dst[dst_index] = av_clip_int16(lrintf(val));
yading@10: #else
yading@10:         val = (val + (1<<(FILTER_SHIFT-1)))>>FILTER_SHIFT;
yading@10:         dst[dst_index] = (unsigned)(val + 32768) > 65535 ? (val>>31) ^ 32767 : val;
yading@10: #endif
yading@10: 
yading@10:         frac += dst_incr_frac;
yading@10:         index += dst_incr;
yading@10:         if(frac >= c->src_incr){
yading@10:             frac -= c->src_incr;
yading@10:             index++;
yading@10:         }
yading@10: 
yading@10:         if(dst_index + 1 == compensation_distance){
yading@10:             compensation_distance= 0;
yading@10:             dst_incr_frac= c->ideal_dst_incr % c->src_incr;
yading@10:             dst_incr=      c->ideal_dst_incr / c->src_incr;
yading@10:         }
yading@10:     }
yading@10:   }
yading@10:     *consumed= FFMAX(index, 0) >> c->phase_shift;
yading@10:     if(index>=0) index &= c->phase_mask;
yading@10: 
yading@10:     if(compensation_distance){
yading@10:         compensation_distance -= dst_index;
yading@10:         av_assert2(compensation_distance > 0);
yading@10:     }
yading@10:     if(update_ctx){
yading@10:         c->frac= frac;
yading@10:         c->index= index;
yading@10:         c->dst_incr= dst_incr_frac + c->src_incr*dst_incr;
yading@10:         c->compensation_distance= compensation_distance;
yading@10:     }
yading@10: 
yading@10:     return dst_index;
yading@10: }
yading@10: 
yading@10: #endif