Subversion Repositories Kolibri OS

Rev

Blame | Last modification | View Log | RSS feed

  1. /*
  2.  * audio resampling
  3.  * Copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg 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.  * FFmpeg 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 FFmpeg; 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 "libavutil/avassert.h"
  29. #include "avcodec.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.     if(!av_reduce(&c->src_incr, &c->dst_incr, out_rate, in_rate * (int64_t)phase_count, INT32_MAX/2))
  214.         goto error;
  215.     c->ideal_dst_incr= c->dst_incr;
  216.  
  217.     c->index= -phase_count*((c->filter_length-1)/2);
  218.  
  219.     return c;
  220. error:
  221.     av_free(c->filter_bank);
  222.     av_free(c);
  223.     return NULL;
  224. }
  225.  
  226. void av_resample_close(AVResampleContext *c){
  227.     av_freep(&c->filter_bank);
  228.     av_freep(&c);
  229. }
  230.  
  231. void av_resample_compensate(AVResampleContext *c, int sample_delta, int compensation_distance){
  232. //    sample_delta += (c->ideal_dst_incr - c->dst_incr)*(int64_t)c->compensation_distance / c->ideal_dst_incr;
  233.     c->compensation_distance= compensation_distance;
  234.     c->dst_incr = c->ideal_dst_incr - c->ideal_dst_incr * (int64_t)sample_delta / compensation_distance;
  235. }
  236.  
  237. int av_resample(AVResampleContext *c, short *dst, short *src, int *consumed, int src_size, int dst_size, int update_ctx){
  238.     int dst_index, i;
  239.     int index= c->index;
  240.     int frac= c->frac;
  241.     int dst_incr_frac= c->dst_incr % c->src_incr;
  242.     int dst_incr=      c->dst_incr / c->src_incr;
  243.     int compensation_distance= c->compensation_distance;
  244.  
  245.   if(compensation_distance == 0 && c->filter_length == 1 && c->phase_shift==0){
  246.         int64_t index2= ((int64_t)index)<<32;
  247.         int64_t incr= (1LL<<32) * c->dst_incr / c->src_incr;
  248.         dst_size= FFMIN(dst_size, (src_size-1-index) * (int64_t)c->src_incr / c->dst_incr);
  249.  
  250.         for(dst_index=0; dst_index < dst_size; dst_index++){
  251.             dst[dst_index] = src[index2>>32];
  252.             index2 += incr;
  253.         }
  254.         index += dst_index * dst_incr;
  255.         index += (frac + dst_index * (int64_t)dst_incr_frac) / c->src_incr;
  256.         frac   = (frac + dst_index * (int64_t)dst_incr_frac) % c->src_incr;
  257.   }else{
  258.     for(dst_index=0; dst_index < dst_size; dst_index++){
  259.         FELEM *filter= c->filter_bank + c->filter_length*(index & c->phase_mask);
  260.         int sample_index= index >> c->phase_shift;
  261.         FELEM2 val=0;
  262.  
  263.         if(sample_index < 0){
  264.             for(i=0; i<c->filter_length; i++)
  265.                 val += src[FFABS(sample_index + i) % src_size] * filter[i];
  266.         }else if(sample_index + c->filter_length > src_size){
  267.             break;
  268.         }else if(c->linear){
  269.             FELEM2 v2=0;
  270.             for(i=0; i<c->filter_length; i++){
  271.                 val += src[sample_index + i] * (FELEM2)filter[i];
  272.                 v2  += src[sample_index + i] * (FELEM2)filter[i + c->filter_length];
  273.             }
  274.             val+=(v2-val)*(FELEML)frac / c->src_incr;
  275.         }else{
  276.             for(i=0; i<c->filter_length; i++){
  277.                 val += src[sample_index + i] * (FELEM2)filter[i];
  278.             }
  279.         }
  280.  
  281. #ifdef CONFIG_RESAMPLE_AUDIOPHILE_KIDDY_MODE
  282.         dst[dst_index] = av_clip_int16(lrintf(val));
  283. #else
  284.         val = (val + (1<<(FILTER_SHIFT-1)))>>FILTER_SHIFT;
  285.         dst[dst_index] = (unsigned)(val + 32768) > 65535 ? (val>>31) ^ 32767 : val;
  286. #endif
  287.  
  288.         frac += dst_incr_frac;
  289.         index += dst_incr;
  290.         if(frac >= c->src_incr){
  291.             frac -= c->src_incr;
  292.             index++;
  293.         }
  294.  
  295.         if(dst_index + 1 == compensation_distance){
  296.             compensation_distance= 0;
  297.             dst_incr_frac= c->ideal_dst_incr % c->src_incr;
  298.             dst_incr=      c->ideal_dst_incr / c->src_incr;
  299.         }
  300.     }
  301.   }
  302.     *consumed= FFMAX(index, 0) >> c->phase_shift;
  303.     if(index>=0) index &= c->phase_mask;
  304.  
  305.     if(compensation_distance){
  306.         compensation_distance -= dst_index;
  307.         av_assert2(compensation_distance > 0);
  308.     }
  309.     if(update_ctx){
  310.         c->frac= frac;
  311.         c->index= index;
  312.         c->dst_incr= dst_incr_frac + c->src_incr*dst_incr;
  313.         c->compensation_distance= compensation_distance;
  314.     }
  315.  
  316.     return dst_index;
  317. }
  318.  
  319. #endif
  320.