lib/envelope.c

   1 /********************************************************************
   2  *                                                                  *
   3  * THIS FILE IS PART OF THE Ogg Vorbis SOFTWARE CODEC SOURCE CODE.  *
   4  * USE, DISTRIBUTION AND REPRODUCTION OF THIS SOURCE IS GOVERNED BY *
   5  * THE GNU PUBLIC LICENSE 2, WHICH IS INCLUDED WITH THIS SOURCE.    *
   6  * PLEASE READ THESE TERMS DISTRIBUTING.                            *
   7  *                                                                  *
   8  * THE OggSQUISH SOURCE CODE IS (C) COPYRIGHT 1994-2000             *
   9  * by Monty <monty@xiph.org> and The XIPHOPHORUS Company            *
  10  * http://www.xiph.org/                                             *
  11  *                                                                  *
  12  ********************************************************************
  13
  14  function: PCM data envelope analysis and manipulation
  15  last mod: $Id: envelope.c,v 1.20 2000/07/12 09:36:17 xiphmont Exp $
  16
  17  Preecho calculation.
  18
  19  ********************************************************************/
  20
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <stdio.h>
  24 #include <math.h>
  25 #include "vorbis/codec.h"
  26
  27 #include "os.h"
  28 #include "scales.h"
  29 #include "envelope.h"
  30 #include "bitwise.h"
  31 #include "misc.h"
  32
  33 /* We use a Chebyshev bandbass for the preecho trigger bandpass; it's
  34    close enough for sample rates 32000-48000 Hz (corner frequencies at
  35    6k/14k assuming sample rate of 44.1kHz) */
  36
  37 /* Digital filter designed by mkfilter/mkshape/gencode A.J. Fisher
  38    Command line: /www/usr/fisher/helpers/mkfilter -Ch \
  39    -6.0000000000e+00 -Bp -o 5 -a 1.3605442177e-01 3.1746031746e-01 -l */
  40
  41 static int    cheb_bandpass_stages=10;
  42 static double cheb_bandpass_gain=5.589612458e+01;
  43 /* z^-stage, z^-stage+1... */
  44 static double cheb_bandpass_B[]={-1.,0.,5.,0.,-10.,0.,10.,0.,-5.,0.,1};
  45 static double cheb_bandpass_A[]={
  46   -0.1917409386,
  47   0.0078657069,
  48   -0.7126903444,
  49   0.0266343467,
  50   -1.4047174730,
  51   0.0466964232,
  52   -1.9032773429,
  53   0.0451493360,
  54   -1.4471447397,
  55   0.0303413711};
  56
  57 static int    cheb_highpass_stages=10;
  58 static double cheb_highpass_gain= 5.291963434e+01;
  59 /* z^-stage, z^-stage+1... */
  60 static double cheb_highpass_B[]={1,-10,45,-120,210,-252,210,-120,45,-10,1};
  61 static double cheb_highpass_A[]={
  62   -0.1247628029,
  63   0.1334086523,
  64   -0.3997715614,
  65   0.3213011089,
  66   -1.1131924119,
  67   1.7692446626,
  68   -3.6241199038,
  69   4.1950871291,
  70   -4.2771757867,
  71   2.3920318913};
  72
  73 void _ve_envelope_init(envelope_lookup *e,vorbis_info *vi){
  74   long rate=vi->rate;
  75   int ch=vi->channels;
  76   int window=vi->envelopesa;
  77   int i;
  78   e->winlength=window;
  79   e->iir=calloc(ch,sizeof(IIR_state));
  80   e->filtered=calloc(ch,sizeof(double *));
  81   e->ch=ch;
  82   e->storage=128;
  83   for(i=0;i<ch;i++){
  84     IIR_init(e->iir+i,cheb_highpass_stages,cheb_highpass_gain,
  85              cheb_highpass_A,cheb_highpass_B);
  86     e->filtered[i]=calloc(e->storage,sizeof(double));
  87   }
  88
  89   drft_init(&e->drft,window);
  90   e->window=malloc(e->winlength*sizeof(double));
  91   /* We just use a straight sin(x) window for this */
  92   for(i=0;i<e->winlength;i++)
  93     e->window[i]=sin((i+.5)/e->winlength*M_PI);
  94 }
  95
  96 void _ve_envelope_clear(envelope_lookup *e){
  97   int i;
  98   for(i=0;i<e->ch;i++){
  99     IIR_clear((e->iir+i));
 100     free(e->filtered[i]);
 101   }
 102   drft_clear(&e->drft);
 103   free(e->window);
 104   free(e->filtered);
 105   memset(e,0,sizeof(envelope_lookup));
 106 }
 107
 108 /*static int frameno=0;*/
 109
 110 static void smooth_noise(long n,double *f,double *noise){
 111   long i;
 112   long lo=0,hi=0;
 113   double acc=0.;
 114
 115   for(i=0;i<n;i++){
 116     long newhi=i*1.0442718740+5;
 117     long newlo=i*.8781245150-5;
 118     if(newhi>n)newhi=n;
 119
 120     for(;lo<newlo;lo++)
 121       acc-=f[lo]*f[lo];
 122     for(;hi<newhi;hi++)
 123       acc+=f[hi]*f[hi];
 124     noise[i]=todB(sqrt(acc/(hi-lo)));
 125   }
 126 }
 127
 128 static double _ve_deltai(envelope_lookup *ve,IIR_state *iir,
 129                       double *pre,double *post){
 130   long no=ve->winlength/3; /* past the highpass rollon! */
 131   long n2=ve->winlength*2;
 132   long n=ve->winlength;
 133
 134   double *workA=alloca(sizeof(double)*n2),A=0.;
 135   double *workB=alloca(sizeof(double)*n2),B=0.;
 136   long i;
 137
 138   /*_analysis_output("A",frameno,pre,n,0,0);
 139     _analysis_output("B",frameno,post,n,0,0);*/
 140
 141   for(i=0;i<n;i++){
 142     workA[i]=pre[i]*ve->window[i];
 143     workB[i]=post[i]*ve->window[i];
 144   }
 145
 146   /*_analysis_output("Awin",frameno,workA,n,0,0);
 147     _analysis_output("Bwin",frameno,workB,n,0,0);*/
 148
 149   drft_forward(&ve->drft,workA);
 150   drft_forward(&ve->drft,workB);
 151   /*_analysis_output("Afft",frameno,workA,n,0,0);
 152     _analysis_output("Bfft",frameno,workB,n,0,0);*/
 153
 154   for(i=0;i<n;i++){
 155     A+=workA[i]*workA[i];
 156     B+=workB[i]*workB[i];
 157   }
 158
 159   A=todB(A);
 160   B=todB(B);
 161
 162   return(B-A);
 163 }
 164
 165 long _ve_envelope_search(vorbis_dsp_state *v,long searchpoint){
 166   vorbis_info *vi=v->vi;
 167   envelope_lookup *ve=v->ve;
 168   long i,j;
 169
 170   /* make sure we have enough storage to match the PCM */
 171   if(v->pcm_storage>ve->storage){
 172     ve->storage=v->pcm_storage;
 173     for(i=0;i<ve->ch;i++)
 174       ve->filtered[i]=realloc(ve->filtered[i],ve->storage*sizeof(double));
 175   }
 176
 177   /* catch up the highpass to match the pcm */
 178   for(i=0;i<ve->ch;i++){
 179     double *filtered=ve->filtered[i];
 180     double *pcm=v->pcm[i];
 181     IIR_state *iir=ve->iir+i;
 182
 183     for(j=ve->current;j<v->pcm_current;j++)
 184       filtered[j]=IIR_filter(iir,pcm[j]);
 185   }
 186   ve->current=v->pcm_current;
 187
 188   /* Now search through our cached highpass data for breaking points */
 189   /* starting point */
 190   if(v->W)
 191     j=v->centerW+vi->blocksizes[1]/4-vi->blocksizes[0]/4;
 192   else
 193     j=v->centerW;
 194
 195   while(j+ve->winlength<=v->pcm_current){
 196     for(i=0;i<ve->ch;i++){
 197       double *filtered=ve->filtered[i]+j;
 198       IIR_state *iir=ve->iir+i;
 199       double m=_ve_deltai(ve,iir,filtered-ve->winlength,filtered);
 200
 201       if(m>vi->preecho_thresh){
 202         /*frameno++;*/
 203         return(0);
 204       }
 205       /*frameno++;*/
 206     }
 207
 208     j+=vi->blocksizes[0]/2;
 209     if(j>=searchpoint)return(1);
 210   }
 211
 212   return(-1);
 213 }
 214
 215 void _ve_envelope_shift(envelope_lookup *e,long shift){
 216   int i;
 217   for(i=0;i<e->ch;i++)
 218     memmove(e->filtered[i],e->filtered[i]+shift,(e->current-shift)*
 219             sizeof(double));
 220   e->current-=shift;
 221 }
 222
 223