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 1.18 2000/06/14 01:38:31 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 "vorbis/codec.h"
  26
  27 #include "os.h"
  28 #include "mdct.h"
  29 #include "envelope.h"
  30 #include "bitwise.h"
  31 #include "window.h"
  32 #include "misc.h"
  33
  34 void _ve_envelope_init(envelope_lookup *e,int samples_per){
  35   int i;
  36
  37   e->winlen=samples_per;
  38   e->window=malloc(e->winlen*sizeof(double));
  39   mdct_init(&e->mdct,e->winlen);
  40
  41   /* We just use a straight sin^2(x) window for this */
  42   for(i=0;i<e->winlen;i++){
  43     e->window[i]=sin((i+.5)/e->winlen*M_PI);
  44     e->window[i]*=e->window[i];
  45   }
  46 }
  47
  48 void _ve_envelope_clear(envelope_lookup *e){
  49   if(e->window)free(e->window);
  50   mdct_clear(&e->mdct);
  51   memset(e,0,sizeof(envelope_lookup));
  52 }
  53
  54 /* use MDCT for spectral power estimation */
  55
  56 static void _ve_deltas(double *deltas,double *pcm,int n,double *window,
  57                        int winsize,mdct_lookup *m){
  58   int i,j;
  59   double *out=alloca(sizeof(double)*winsize);
  60
  61   for(j=0;j<n;j++){
  62     double acc=0.;
  63
  64     memcpy(out,pcm+j*winsize,winsize*sizeof(double));
  65     for(i=0;i<winsize;i++)
  66       out[i]*=window[i];
  67
  68     mdct_forward(m,out,out);
  69
  70     for(i=winsize/10;i<winsize/2;i++)
  71       acc+=fabs(out[i]);
  72     if(deltas[j]<acc)deltas[j]=acc;
  73   }
  74 }
  75
  76 void _ve_envelope_deltas(vorbis_dsp_state *v){
  77   vorbis_info *vi=v->vi;
  78   int step=vi->envelopesa;
  79
  80   int dtotal=v->pcm_current/vi->envelopesa;
  81   int dcurr=v->envelope_current;
  82   int pch;
  83
  84   if(dtotal>dcurr){
  85     double *mult=v->multipliers+dcurr;
  86     memset(mult,0,sizeof(double)*(dtotal-dcurr));
  87
  88     for(pch=0;pch<vi->channels;pch++){
  89       double *pcm=v->pcm[pch]+dcurr*step;
  90       _ve_deltas(mult,pcm,dtotal-dcurr,v->ve.window,v->ve.winlen,&v->ve.mdct);
  91     }
  92     v->envelope_current=dtotal;
  93
  94   }
  95 }
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