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 1.29 2001/01/22 01:38:24 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+01f;
  45 static float cheb_bandpass_B[]={-1.f,0.f,5.f,0.f,-10.f,0.f,
  46                                 10.f,0.f,-5.f,0.f,1f};
  47 static float cheb_bandpass_A[]={
  48   -0.1917409386f,
  49   0.0078657069f,
  50   -0.7126903444f,
  51   0.0266343467f,
  52   -1.4047174730f,
  53   0.0466964232f,
  54   -1.9032773429f,
  55   0.0451493360f,
  56   -1.4471447397f,
  57   0.0303413711f};
  58 #endif
  59
  60 static int    cheb_highpass_stages=10;
  61 static float cheb_highpass_gain= 5.291963434e+01f;
  62 /* z^-stage, z^-stage+1... */
  63 static float cheb_highpass_B[]={1.f,-10.f,45.f,-120.f,210.f,
  64                                 -252.f,210.f,-120.f,45.f,-10.f,1.f};
  65 static float cheb_highpass_A[]={
  66   -0.1247628029f,
  67   0.1334086523f,
  68   -0.3997715614f,
  69   0.3213011089f,
  70   -1.1131924119f,
  71   1.7692446626f,
  72   -3.6241199038f,
  73   4.1950871291f,
  74   -4.2771757867f,
  75   2.3920318913f};
  76
  77 void _ve_envelope_init(envelope_lookup *e,vorbis_info *vi){
  78   codec_setup_info *ci=vi->codec_setup;
  79   int ch=vi->channels;
  80   int window=ci->envelopesa;
  81   int i;
  82   e->winlength=window;
  83   e->minenergy=fromdB(ci->preecho_minenergy);
  84   e->iir=_ogg_calloc(ch,sizeof(IIR_state));
  85   e->filtered=_ogg_calloc(ch,sizeof(float *));
  86   e->ch=ch;
  87   e->storage=128;
  88   for(i=0;i<ch;i++){
  89     IIR_init(e->iir+i,cheb_highpass_stages,cheb_highpass_gain,
  90              cheb_highpass_A,cheb_highpass_B);
  91     e->filtered[i]=_ogg_calloc(e->storage,sizeof(float));
  92   }
  93
  94   drft_init(&e->drft,window);
  95   e->window=_ogg_malloc(e->winlength*sizeof(float));
  96   /* We just use a straight sin(x) window for this */
  97   for(i=0;i<e->winlength;i++)
  98     e->window[i]=sin((i+.5)/e->winlength*M_PI);
  99 }
 100
 101 void _ve_envelope_clear(envelope_lookup *e){
 102   int i;
 103   for(i=0;i<e->ch;i++){
 104     IIR_clear((e->iir+i));
 105     _ogg_free(e->filtered[i]);
 106   }
 107   drft_clear(&e->drft);
 108   _ogg_free(e->window);
 109   _ogg_free(e->filtered);
 110   _ogg_free(e->iir);
 111   memset(e,0,sizeof(envelope_lookup));
 112 }
 113
 114 /* straight threshhold based until we find something that works better
 115    and isn't patented */
 116 static float _ve_deltai(envelope_lookup *ve,float *pre,float *post){
 117   long n=ve->winlength;
 118
 119   long i;
 120
 121   /* we want to have a 'minimum bar' for energy, else we're just
 122      basing blocks on quantization noise that outweighs the signal
 123      itself (for low power signals) */
 124
 125   float min=ve->minenergy;
 126   float A=min*min*n;
 127   float B=A;
 128
 129   /*_analysis_output("A",granulepos,pre,n,0,0);
 130     _analysis_output("B",granulepos,post,n,0,0);*/
 131
 132   for(i=0;i<n;i++){
 133     A+=pre[i]*pre[i];
 134     B+=post[i]*post[i];
 135   }
 136
 137   A=todB(A);
 138   B=todB(B);
 139
 140   return(B-A);
 141 }
 142
 143 static float _ve_ampi(envelope_lookup *ve,float *pre){
 144   long n=ve->winlength;
 145
 146   long i;
 147
 148   /* we want to have a 'minimum bar' for energy, else we're just
 149      basing blocks on quantization noise that outweighs the signal
 150      itself (for low power signals) */
 151
 152   float min=ve->minenergy;
 153   float A=min*min*n;
 154
 155   for(i=0;i<n;i++){
 156     A+=pre[i]*pre[i];
 157   }
 158
 159   A=todB(A);
 160   return(A);
 161 }
 162
 163 long _ve_envelope_search(vorbis_dsp_state *v,long searchpoint){
 164   vorbis_info *vi=v->vi;
 165   codec_setup_info *ci=vi->codec_setup;
 166   envelope_lookup *ve=((backend_lookup_state *)(v->backend_state))->ve;
 167   long i,j;
 168
 169   /* make sure we have enough storage to match the PCM */
 170   if(v->pcm_storage>ve->storage){
 171     ve->storage=v->pcm_storage;
 172     for(i=0;i<ve->ch;i++)
 173       ve->filtered[i]=_ogg_realloc(ve->filtered[i],ve->storage*sizeof(float));
 174   }
 175
 176   /* catch up the highpass to match the pcm */
 177   for(i=0;i<ve->ch;i++){
 178     float *filtered=ve->filtered[i];
 179     float *pcm=v->pcm[i];
 180     IIR_state *iir=ve->iir+i;
 181     int flag=1;
 182
 183     for(j=ve->current;j<v->pcm_current;j++){
 184       filtered[j]=IIR_filter(iir,pcm[j]);
 185       if(pcm[j])flag=0;
 186     }
 187     if(flag && ve->current+64<v->pcm_current)IIR_reset(iir);
 188   }
 189
 190   ve->current=v->pcm_current;
 191
 192   /* Now search through our cached highpass data for breaking points */
 193   /* starting point */
 194   if(v->W)
 195     j=v->centerW+ci->blocksizes[1]/4-ci->blocksizes[0]/4;
 196   else
 197     j=v->centerW;
 198
 199   while(j+ve->winlength<=v->pcm_current){
 200     for(i=0;i<ve->ch;i++){
 201       float *filtered=ve->filtered[i]+j;
 202       float m=_ve_deltai(ve,filtered-ve->winlength,filtered);
 203
 204       if(m>ci->preecho_thresh){
 205         /*granulepos++;*/
 206         return(0);
 207       }
 208       if(m<ci->postecho_thresh){
 209         /*granulepos++;*/
 210         return(0);
 211       }
 212       /*granulepos++;*/
 213     }
 214
 215     j+=min(ci->blocksizes[0],ve->winlength)/2;
 216
 217     if(j>=searchpoint){
 218       return(1);
 219     }
 220   }
 221
 222   return(-1);
 223 }
 224
 225 void _ve_envelope_shift(envelope_lookup *e,long shift){
 226   int i;
 227   for(i=0;i<e->ch;i++)
 228     memmove(e->filtered[i],e->filtered[i]+shift,(e->current-shift)*
 229             sizeof(float));
 230   e->current-=shift;
 231 }
 232
 233