lib/envelope.c

   1 /********************************************************************
   2  *                                                                  *
   3  * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE.   *
   4  * USE, DISTRIBUTION AND REPRODUCTION OF THIS SOURCE IS GOVERNED BY *
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   6  * THIS SOURCE. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.        *
   7  *                                                                  *
   8  * THE OggVorbis 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 1.25 2000/11/07 09:51:42 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 <ogg/ogg.h>
  26 #include "vorbis/codec.h"
  27 #include "codec_internal.h"
  28
  29 #include "os.h"
  30 #include "scales.h"
  31 #include "envelope.h"
  32 #include "misc.h"
  33
  34 /* We use a Chebyshev bandbass for the preecho trigger bandpass; it's
  35    close enough for sample rates 32000-48000 Hz (corner frequencies at
  36    6k/14k assuming sample rate of 44.1kHz) */
  37
  38 /* Digital filter designed by mkfilter/mkshape/gencode A.J. Fisher
  39    Command line: /www/usr/fisher/helpers/mkfilter -Ch \
  40    -6.0000000000e+00 -Bp -o 5 -a 1.3605442177e-01 3.1746031746e-01 -l */
  41
  42 #if 0
  43 static int    cheb_bandpass_stages=10;
  44 static float cheb_bandpass_gain=5.589612458e+01;
  45 static float cheb_bandpass_B[]={-1.,0.,5.,0.,-10.,0.,10.,0.,-5.,0.,1};
  46 static float cheb_bandpass_A[]={
  47   -0.1917409386,
  48   0.0078657069,
  49   -0.7126903444,
  50   0.0266343467,
  51   -1.4047174730,
  52   0.0466964232,
  53   -1.9032773429,
  54   0.0451493360,
  55   -1.4471447397,
  56   0.0303413711};
  57 #endif
  58
  59 static int    cheb_highpass_stages=10;
  60 static float cheb_highpass_gain= 5.291963434e+01;
  61 /* z^-stage, z^-stage+1... */
  62 static float cheb_highpass_B[]={1,-10,45,-120,210,-252,210,-120,45,-10,1};
  63 static float cheb_highpass_A[]={
  64   -0.1247628029,
  65   0.1334086523,
  66   -0.3997715614,
  67   0.3213011089,
  68   -1.1131924119,
  69   1.7692446626,
  70   -3.6241199038,
  71   4.1950871291,
  72   -4.2771757867,
  73   2.3920318913};
  74
  75 void _ve_envelope_init(envelope_lookup *e,vorbis_info *vi){
  76   codec_setup_info *ci=vi->codec_setup;
  77   int ch=vi->channels;
  78   int window=ci->envelopesa;
  79   int i;
  80   e->winlength=window;
  81   e->minenergy=fromdB(ci->preecho_minenergy);
  82   e->iir=_ogg_calloc(ch,sizeof(IIR_state));
  83   e->filtered=_ogg_calloc(ch,sizeof(float *));
  84   e->ch=ch;
  85   e->storage=128;
  86   for(i=0;i<ch;i++){
  87     IIR_init(e->iir+i,cheb_highpass_stages,cheb_highpass_gain,
  88              cheb_highpass_A,cheb_highpass_B);
  89     e->filtered[i]=_ogg_calloc(e->storage,sizeof(float));
  90   }
  91
  92   drft_init(&e->drft,window);
  93   e->window=_ogg_malloc(e->winlength*sizeof(float));
  94   /* We just use a straight sin(x) window for this */
  95   for(i=0;i<e->winlength;i++)
  96     e->window[i]=sin((i+.5)/e->winlength*M_PI);
  97 }
  98
  99 void _ve_envelope_clear(envelope_lookup *e){
 100   int i;
 101   for(i=0;i<e->ch;i++){
 102     IIR_clear((e->iir+i));
 103     free(e->filtered[i]);
 104   }
 105   drft_clear(&e->drft);
 106   free(e->window);
 107   free(e->filtered);
 108   memset(e,0,sizeof(envelope_lookup));
 109 }
 110
 111 static float _ve_deltai(envelope_lookup *ve,IIR_state *iir,
 112                       float *pre,float *post){
 113   long n2=ve->winlength*2;
 114   long n=ve->winlength;
 115
 116   float *workA=alloca(sizeof(float)*n2),A=0.;
 117   float *workB=alloca(sizeof(float)*n2),B=0.;
 118   long i;
 119
 120   /*_analysis_output("A",granulepos,pre,n,0,0);
 121     _analysis_output("B",granulepos,post,n,0,0);*/
 122
 123   for(i=0;i<n;i++){
 124     workA[i]=pre[i]*ve->window[i];
 125     workB[i]=post[i]*ve->window[i];
 126   }
 127
 128   /*_analysis_output("Awin",granulepos,workA,n,0,0);
 129     _analysis_output("Bwin",granulepos,workB,n,0,0);*/
 130
 131   drft_forward(&ve->drft,workA);
 132   drft_forward(&ve->drft,workB);
 133
 134   /* we want to have a 'minimum bar' for energy, else we're just
 135      basing blocks on quantization noise that outweighs the signal
 136      itself (for low power signals) */
 137   {
 138     float min=ve->minenergy;
 139     for(i=0;i<n;i++){
 140       if(fabs(workA[i])<min)workA[i]=min;
 141       if(fabs(workB[i])<min)workB[i]=min;
 142     }
 143   }
 144
 145   /*_analysis_output("Afft",granulepos,workA,n,0,0);
 146     _analysis_output("Bfft",granulepos,workB,n,0,0);*/
 147
 148   for(i=0;i<n;i++){
 149     A+=workA[i]*workA[i];
 150     B+=workB[i]*workB[i];
 151   }
 152
 153   A=todB(A);
 154   B=todB(B);
 155
 156   return(B-A);
 157 }
 158
 159 long _ve_envelope_search(vorbis_dsp_state *v,long searchpoint){
 160   vorbis_info *vi=v->vi;
 161   codec_setup_info *ci=vi->codec_setup;
 162   envelope_lookup *ve=((backend_lookup_state *)(v->backend_state))->ve;
 163   long i,j;
 164
 165   /* make sure we have enough storage to match the PCM */
 166   if(v->pcm_storage>ve->storage){
 167     ve->storage=v->pcm_storage;
 168     for(i=0;i<ve->ch;i++)
 169       ve->filtered[i]=_ogg_realloc(ve->filtered[i],ve->storage*sizeof(float));
 170   }
 171
 172   /* catch up the highpass to match the pcm */
 173   for(i=0;i<ve->ch;i++){
 174     float *filtered=ve->filtered[i];
 175     float *pcm=v->pcm[i];
 176     IIR_state *iir=ve->iir+i;
 177     int flag=1;
 178
 179     for(j=ve->current;j<v->pcm_current;j++){
 180       filtered[j]=IIR_filter(iir,pcm[j]);
 181       if(pcm[j])flag=0;
 182     }
 183     if(flag && ve->current+64<v->pcm_current)IIR_reset(iir);
 184   }
 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+ci->blocksizes[1]/4-ci->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       float *filtered=ve->filtered[i]+j;
 198       IIR_state *iir=ve->iir+i;
 199       float m=_ve_deltai(ve,iir,filtered-ve->winlength,filtered);
 200
 201       if(m>ci->preecho_thresh){
 202         /*granulepos++;*/
 203         return(0);
 204       }
 205       /*granulepos++;*/
 206     }
 207
 208     j+=ci->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(float));
 220   e->current-=shift;
 221 }
 222
 223