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 *
   5  * THE GNU LESSER/LIBRARY PUBLIC LICENSE, WHICH IS INCLUDED WITH    *
   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 1.30 2001/01/31 23:58:49 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 /* Digital filter designed by mkfilter/mkshape/gencode A.J. Fisher
  35    Command line: /www/usr/fisher/helpers/mkfilter -Ch \
  36    -6.0000000000e+00 -Bp -o 5 -a 1.3605442177e-01 3.1746031746e-01 -l */
  37
  38 #if 0
  39 static int    cheb_bandpass_stages=10;
  40 static float cheb_bandpass_gain=5.589612458e+01f;
  41 static float cheb_bandpass_B[]={-1.f,0.f,5.f,0.f,-10.f,0.f,
  42                                 10.f,0.f,-5.f,0.f,1f};
  43 static float cheb_bandpass_A[]={
  44   -0.1917409386f,
  45   0.0078657069f,
  46   -0.7126903444f,
  47   0.0266343467f,
  48   -1.4047174730f,
  49   0.0466964232f,
  50   -1.9032773429f,
  51   0.0451493360f,
  52   -1.4471447397f,
  53   0.0303413711f};
  54 #endif
  55
  56 /* 4kHz Chebyshev highpass */
  57 static int    cheb_highpass_stages=10;
  58 static float cheb_highpass_gain= 1.314337427e+01f;
  59 /* z^-stage, z^-stage+1... */
  60 static float cheb_highpass_B[]={1.f,-10.f,45.f,-120.f,210.f,
  61                                 -252.f,210.f,-120.f,45.f,-10.f,1.f};
  62 static float cheb_highpass_A[]={
  63   -0.1013448254f,
  64   0.4524819695f,
  65   -1.3268091670f,
  66   3.2875726855f,
  67   -7.2782468961f,
  68   13.0298867474f,
  69   -17.6698599469f,
  70   17.2757670409f,
  71   -11.6207967046f,
  72   4.8672119675f};
  73
  74 #if 0
  75 /* 6kHz Chebyshev highpass */
  76 static int    cheb_highpass_stages=10;
  77 static float cheb_highpass_gain= 5.291963434e+01f;
  78 /* z^-stage, z^-stage+1... */
  79 static float cheb_highpass_B[]={1.f,-10.f,45.f,-120.f,210.f,
  80                                 -252.f,210.f,-120.f,45.f,-10.f,1.f};
  81 static float cheb_highpass_A[]={
  82   -0.1247628029f,
  83   0.1334086523f,
  84   -0.3997715614f,
  85   0.3213011089f,
  86   -1.1131924119f,
  87   1.7692446626f,
  88   -3.6241199038f,
  89   4.1950871291f,
  90   -4.2771757867f,
  91   2.3920318913f};
  92 #endif
  93
  94 void _ve_envelope_init(envelope_lookup *e,vorbis_info *vi){
  95   codec_setup_info *ci=vi->codec_setup;
  96   int ch=vi->channels;
  97   int window=ci->envelopesa;
  98   int i;
  99   e->winlength=window;
 100   e->minenergy=fromdB(ci->preecho_minenergy);
 101   e->iir=_ogg_calloc(ch,sizeof(IIR_state));
 102   e->filtered=_ogg_calloc(ch,sizeof(float *));
 103   e->ch=ch;
 104   e->storage=128;
 105   for(i=0;i<ch;i++){
 106     IIR_init(e->iir+i,cheb_highpass_stages,cheb_highpass_gain,
 107              cheb_highpass_A,cheb_highpass_B);
 108     e->filtered[i]=_ogg_calloc(e->storage,sizeof(float));
 109   }
 110
 111   drft_init(&e->drft,window);
 112   e->window=_ogg_malloc(e->winlength*sizeof(float));
 113   /* We just use a straight sin(x) window for this */
 114   for(i=0;i<e->winlength;i++)
 115     e->window[i]=sin((i+.5)/e->winlength*M_PI);
 116 }
 117
 118 void _ve_envelope_clear(envelope_lookup *e){
 119   int i;
 120   for(i=0;i<e->ch;i++){
 121     IIR_clear((e->iir+i));
 122     _ogg_free(e->filtered[i]);
 123   }
 124   drft_clear(&e->drft);
 125   _ogg_free(e->window);
 126   _ogg_free(e->filtered);
 127   _ogg_free(e->iir);
 128   memset(e,0,sizeof(envelope_lookup));
 129 }
 130
 131 /* straight threshhold based until we find something that works better
 132    and isn't patented */
 133 static float _ve_deltai(envelope_lookup *ve,float *pre,float *post){
 134   long n=ve->winlength;
 135
 136   long i;
 137
 138   /* we want to have a 'minimum bar' for energy, else we're just
 139      basing blocks on quantization noise that outweighs the signal
 140      itself (for low power signals) */
 141
 142   float min=ve->minenergy;
 143   float A=min*min*n;
 144   float B=A;
 145
 146   /*_analysis_output("A",granulepos,pre,n,0,0);
 147     _analysis_output("B",granulepos,post,n,0,0);*/
 148
 149   for(i=0;i<n;i++){
 150     A+=pre[i]*pre[i];
 151     B+=post[i]*post[i];
 152   }
 153
 154   A=todB(A);
 155   B=todB(B);
 156
 157   return(B-A);
 158 }
 159
 160 static float _ve_ampi(envelope_lookup *ve,float *pre){
 161   long n=ve->winlength;
 162
 163   long i;
 164
 165   /* we want to have a 'minimum bar' for energy, else we're just
 166      basing blocks on quantization noise that outweighs the signal
 167      itself (for low power signals) */
 168
 169   float min=ve->minenergy;
 170   float A=min*min*n;
 171
 172   for(i=0;i<n;i++){
 173     A+=pre[i]*pre[i];
 174   }
 175
 176   A=todB(A);
 177   return(A);
 178 }
 179
 180 long _ve_envelope_search(vorbis_dsp_state *v,long searchpoint){
 181   vorbis_info *vi=v->vi;
 182   codec_setup_info *ci=vi->codec_setup;
 183   envelope_lookup *ve=((backend_lookup_state *)(v->backend_state))->ve;
 184   long i,j,k;
 185   float *work=alloca(sizeof(float)*ve->winlength*2);
 186
 187   /* make sure we have enough storage to match the PCM */
 188   if(v->pcm_storage>ve->storage){
 189     ve->storage=v->pcm_storage;
 190     for(i=0;i<ve->ch;i++)
 191       ve->filtered[i]=_ogg_realloc(ve->filtered[i],ve->storage*sizeof(float));
 192   }
 193
 194   /* catch up the highpass to match the pcm */
 195   for(i=0;i<ve->ch;i++){
 196     float *filtered=ve->filtered[i];
 197     float *pcm=v->pcm[i];
 198     IIR_state *iir=ve->iir+i;
 199     int flag=1;
 200
 201     for(j=ve->current;j<v->pcm_current;j++){
 202       filtered[j]=IIR_filter(iir,pcm[j]);
 203       if(pcm[j])flag=0;
 204     }
 205     if(flag && ve->current+64<v->pcm_current)IIR_reset(iir);
 206   }
 207
 208   ve->current=v->pcm_current;
 209
 210   /* Now search through our cached highpass data for breaking points */
 211   /* starting point */
 212   if(v->W)
 213     j=v->centerW+ci->blocksizes[1]/4-ci->blocksizes[0]/4;
 214   else
 215     j=v->centerW;
 216
 217   while(j+ve->winlength<=v->pcm_current){
 218     for(i=0;i<ve->ch;i++){
 219       float *filtered=ve->filtered[i]+j;
 220       float m=_ve_deltai(ve,filtered-ve->winlength,filtered);
 221
 222       if(m>ci->preecho_thresh){
 223         /*granulepos++;*/
 224         return(0);
 225       }
 226       if(m<ci->postecho_thresh){
 227         /*granulepos++;*/
 228         return(0);
 229       }
 230       /*granulepos++;*/
 231     }
 232
 233     /* look also for preecho in coupled channel pairs with the center
 234        subtracted out (A-B) */
 235     for(i=1;i<ve->ch;i+=2){
 236       float *filteredA=ve->filtered[i-1]+j-ve->winlength;
 237       float *filteredB=ve->filtered[i]+j-ve->winlength;
 238       float m;
 239
 240       for(k=0;k<ve->winlength*2;k++)
 241         work[k]=filteredA[k]-filteredB[k];
 242
 243       m=_ve_deltai(ve,work,work+ve->winlength);
 244
 245       if(m>ci->preecho_thresh){
 246         /*granulepos++;*/
 247         return(0);
 248       }
 249       if(m<ci->postecho_thresh){
 250         /*granulepos++;*/
 251         return(0);
 252       }
 253       /*granulepos++;*/
 254     }
 255
 256
 257     j+=min(ci->blocksizes[0],ve->winlength)/2;
 258
 259     if(j>=searchpoint){
 260       return(1);
 261     }
 262   }
 263
 264   return(-1);
 265 }
 266
 267 void _ve_envelope_shift(envelope_lookup *e,long shift){
 268   int i;
 269   for(i=0;i<e->ch;i++)
 270     memmove(e->filtered[i],e->filtered[i]+shift,(e->current-shift)*
 271             sizeof(float));
 272   e->current-=shift;
 273 }
 274
 275