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 1.28 2000/12/21 21:04:39 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 static float _ve_deltai(envelope_lookup *ve,
 115                       float *pre,float *post){
 116   long n2=ve->winlength*2;
 117   long n=ve->winlength;
 118
 119   float *workA=alloca(sizeof(float)*n2),A=0.f;
 120   float *workB=alloca(sizeof(float)*n2),B=0.f;
 121   long i;
 122
 123   /*_analysis_output("A",granulepos,pre,n,0,0);
 124     _analysis_output("B",granulepos,post,n,0,0);*/
 125
 126   for(i=0;i<n;i++){
 127     workA[i]=pre[i]*ve->window[i];
 128     workB[i]=post[i]*ve->window[i];
 129   }
 130
 131   /*_analysis_output("Awin",granulepos,workA,n,0,0);
 132     _analysis_output("Bwin",granulepos,workB,n,0,0);*/
 133
 134   drft_forward(&ve->drft,workA);
 135   drft_forward(&ve->drft,workB);
 136
 137   /* we want to have a 'minimum bar' for energy, else we're just
 138      basing blocks on quantization noise that outweighs the signal
 139      itself (for low power signals) */
 140   {
 141     float min=ve->minenergy;
 142     for(i=0;i<n;i++){
 143       if(fabs(workA[i])<min)workA[i]=min;
 144       if(fabs(workB[i])<min)workB[i]=min;
 145     }
 146   }
 147
 148   /*_analysis_output("Afft",granulepos,workA,n,0,0);
 149     _analysis_output("Bfft",granulepos,workB,n,0,0);*/
 150
 151   for(i=0;i<n;i++){
 152     A+=workA[i]*workA[i];
 153     B+=workB[i]*workB[i];
 154   }
 155
 156   A=todB(A);
 157   B=todB(B);
 158
 159   return(B-A);
 160 }
 161
 162 long _ve_envelope_search(vorbis_dsp_state *v,long searchpoint){
 163   vorbis_info *vi=v->vi;
 164   codec_setup_info *ci=vi->codec_setup;
 165   envelope_lookup *ve=((backend_lookup_state *)(v->backend_state))->ve;
 166   long i,j;
 167
 168   /* make sure we have enough storage to match the PCM */
 169   if(v->pcm_storage>ve->storage){
 170     ve->storage=v->pcm_storage;
 171     for(i=0;i<ve->ch;i++)
 172       ve->filtered[i]=_ogg_realloc(ve->filtered[i],ve->storage*sizeof(float));
 173   }
 174
 175   /* catch up the highpass to match the pcm */
 176   for(i=0;i<ve->ch;i++){
 177     float *filtered=ve->filtered[i];
 178     float *pcm=v->pcm[i];
 179     IIR_state *iir=ve->iir+i;
 180     int flag=1;
 181
 182     for(j=ve->current;j<v->pcm_current;j++){
 183       filtered[j]=IIR_filter(iir,pcm[j]);
 184       if(pcm[j])flag=0;
 185     }
 186     if(flag && ve->current+64<v->pcm_current)IIR_reset(iir);
 187   }
 188
 189   ve->current=v->pcm_current;
 190
 191   /* Now search through our cached highpass data for breaking points */
 192   /* starting point */
 193   if(v->W)
 194     j=v->centerW+ci->blocksizes[1]/4-ci->blocksizes[0]/4;
 195   else
 196     j=v->centerW;
 197
 198   while(j+ve->winlength<=v->pcm_current){
 199     for(i=0;i<ve->ch;i++){
 200       float *filtered=ve->filtered[i]+j;
 201       float m=_ve_deltai(ve,filtered-ve->winlength,filtered);
 202
 203       if(m>ci->preecho_thresh){
 204         /*granulepos++;*/
 205         return(0);
 206       }
 207       /*granulepos++;*/
 208     }
 209
 210     j+=ci->blocksizes[0]/2;
 211     if(j>=searchpoint)return(1);
 212   }
 213
 214   return(-1);
 215 }
 216
 217 void _ve_envelope_shift(envelope_lookup *e,long shift){
 218   int i;
 219   for(i=0;i<e->ch;i++)
 220     memmove(e->filtered[i],e->filtered[i]+shift,(e->current-shift)*
 221             sizeof(float));
 222   e->current-=shift;
 223 }
 224
 225