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 1.23 2000/10/12 03:12:52 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
  28 #include "os.h"
  29 #include "scales.h"
  30 #include "envelope.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 #if 0
  42 static int    cheb_bandpass_stages=10;
  43 static float cheb_bandpass_gain=5.589612458e+01;
  44 static float cheb_bandpass_B[]={-1.,0.,5.,0.,-10.,0.,10.,0.,-5.,0.,1};
  45 static float 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 #endif
  57
  58 static int    cheb_highpass_stages=10;
  59 static float cheb_highpass_gain= 5.291963434e+01;
  60 /* z^-stage, z^-stage+1... */
  61 static float cheb_highpass_B[]={1,-10,45,-120,210,-252,210,-120,45,-10,1};
  62 static float cheb_highpass_A[]={
  63   -0.1247628029,
  64   0.1334086523,
  65   -0.3997715614,
  66   0.3213011089,
  67   -1.1131924119,
  68   1.7692446626,
  69   -3.6241199038,
  70   4.1950871291,
  71   -4.2771757867,
  72   2.3920318913};
  73
  74 void _ve_envelope_init(envelope_lookup *e,vorbis_info *vi){
  75   int ch=vi->channels;
  76   int window=vi->envelopesa;
  77   int i;
  78   e->winlength=window;
  79   e->minenergy=fromdB(vi->preecho_minenergy);
  80   e->iir=calloc(ch,sizeof(IIR_state));
  81   e->filtered=calloc(ch,sizeof(float *));
  82   e->ch=ch;
  83   e->storage=128;
  84   for(i=0;i<ch;i++){
  85     IIR_init(e->iir+i,cheb_highpass_stages,cheb_highpass_gain,
  86              cheb_highpass_A,cheb_highpass_B);
  87     e->filtered[i]=calloc(e->storage,sizeof(float));
  88   }
  89
  90   drft_init(&e->drft,window);
  91   e->window=malloc(e->winlength*sizeof(float));
  92   /* We just use a straight sin(x) window for this */
  93   for(i=0;i<e->winlength;i++)
  94     e->window[i]=sin((i+.5)/e->winlength*M_PI);
  95 }
  96
  97 void _ve_envelope_clear(envelope_lookup *e){
  98   int i;
  99   for(i=0;i<e->ch;i++){
 100     IIR_clear((e->iir+i));
 101     free(e->filtered[i]);
 102   }
 103   drft_clear(&e->drft);
 104   free(e->window);
 105   free(e->filtered);
 106   memset(e,0,sizeof(envelope_lookup));
 107 }
 108
 109 static float _ve_deltai(envelope_lookup *ve,IIR_state *iir,
 110                       float *pre,float *post){
 111   long n2=ve->winlength*2;
 112   long n=ve->winlength;
 113
 114   float *workA=alloca(sizeof(float)*n2),A=0.;
 115   float *workB=alloca(sizeof(float)*n2),B=0.;
 116   long i;
 117
 118   /*_analysis_output("A",granulepos,pre,n,0,0);
 119     _analysis_output("B",granulepos,post,n,0,0);*/
 120
 121   for(i=0;i<n;i++){
 122     workA[i]=pre[i]*ve->window[i];
 123     workB[i]=post[i]*ve->window[i];
 124   }
 125
 126   /*_analysis_output("Awin",granulepos,workA,n,0,0);
 127     _analysis_output("Bwin",granulepos,workB,n,0,0);*/
 128
 129   drft_forward(&ve->drft,workA);
 130   drft_forward(&ve->drft,workB);
 131
 132   /* we want to have a 'minimum bar' for energy, else we're just
 133      basing blocks on quantization noise that outweighs the signal
 134      itself (for low power signals) */
 135   {
 136     float min=ve->minenergy;
 137     for(i=0;i<n;i++){
 138       if(fabs(workA[i])<min)workA[i]=min;
 139       if(fabs(workB[i])<min)workB[i]=min;
 140     }
 141   }
 142
 143   /*_analysis_output("Afft",granulepos,workA,n,0,0);
 144     _analysis_output("Bfft",granulepos,workB,n,0,0);*/
 145
 146   for(i=0;i<n;i++){
 147     A+=workA[i]*workA[i];
 148     B+=workB[i]*workB[i];
 149   }
 150
 151   A=todB(A);
 152   B=todB(B);
 153
 154   return(B-A);
 155 }
 156
 157 long _ve_envelope_search(vorbis_dsp_state *v,long searchpoint){
 158   vorbis_info *vi=v->vi;
 159   envelope_lookup *ve=v->ve;
 160   long i,j;
 161
 162   /* make sure we have enough storage to match the PCM */
 163   if(v->pcm_storage>ve->storage){
 164     ve->storage=v->pcm_storage;
 165     for(i=0;i<ve->ch;i++)
 166       ve->filtered[i]=realloc(ve->filtered[i],ve->storage*sizeof(float));
 167   }
 168
 169   /* catch up the highpass to match the pcm */
 170   for(i=0;i<ve->ch;i++){
 171     float *filtered=ve->filtered[i];
 172     float *pcm=v->pcm[i];
 173     IIR_state *iir=ve->iir+i;
 174
 175     for(j=ve->current;j<v->pcm_current;j++)
 176       filtered[j]=IIR_filter(iir,pcm[j]);
 177   }
 178   ve->current=v->pcm_current;
 179
 180   /* Now search through our cached highpass data for breaking points */
 181   /* starting point */
 182   if(v->W)
 183     j=v->centerW+vi->blocksizes[1]/4-vi->blocksizes[0]/4;
 184   else
 185     j=v->centerW;
 186
 187   while(j+ve->winlength<=v->pcm_current){
 188     for(i=0;i<ve->ch;i++){
 189       float *filtered=ve->filtered[i]+j;
 190       IIR_state *iir=ve->iir+i;
 191       float m=_ve_deltai(ve,iir,filtered-ve->winlength,filtered);
 192
 193       if(m>vi->preecho_thresh){
 194         /*granulepos++;*/
 195         return(0);
 196       }
 197       /*granulepos++;*/
 198     }
 199
 200     j+=vi->blocksizes[0]/2;
 201     if(j>=searchpoint)return(1);
 202   }
 203
 204   return(-1);
 205 }
 206
 207 void _ve_envelope_shift(envelope_lookup *e,long shift){
 208   int i;
 209   for(i=0;i<e->ch;i++)
 210     memmove(e->filtered[i],e->filtered[i]+shift,(e->current-shift)*
 211             sizeof(float));
 212   e->current-=shift;
 213 }
 214
 215