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/********************************************************************
* *
* THIS FILE IS PART OF THE Ogg Vorbis SOFTWARE CODEC SOURCE CODE. *
* USE, DISTRIBUTION AND REPRODUCTION OF THIS SOURCE IS GOVERNED BY *
* THE GNU PUBLIC LICENSE 2, WHICH IS INCLUDED WITH THIS SOURCE. *
* PLEASE READ THESE TERMS DISTRIBUTING. *
* *
* THE OggSQUISH SOURCE CODE IS (C) COPYRIGHT 1994-2000 *
* by Monty <monty@xiph.org> and The XIPHOPHORUS Company *
* http://www.xiph.org/ *
* *
********************************************************************
function: PCM data envelope analysis and manipulation
last mod: $Id: envelope.c,v 1.15.4.1 2000/05/08 08:25:42 xiphmont Exp $
Preecho calculation.
********************************************************************/
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <math.h>
#include "vorbis/codec.h"
#include "os.h"
#include "mdct.h"
#include "envelope.h"
#include "bitwise.h"
#include "window.h"
void _ve_envelope_init(envelope_lookup *e,int samples_per){
int i;
e->winlen=samples_per;
e->window=malloc(e->winlen*sizeof(double));
mdct_init(&e->mdct,e->winlen);
/* We just use a straight sin(x) window for this */
for(i=0;i<e->winlen;i++)
e->window[i]=sin((i+.5)/e->winlen*M_PI);
}
void _ve_envelope_clear(envelope_lookup *e){
if(e->window)free(e->window);
mdct_clear(&e->mdct);
memset(e,0,sizeof(envelope_lookup));
}
/* use MDCT for spectral power estimation */
static void _ve_deltas(double *deltas,double *pcm,int n,double *window,
int winsize,mdct_lookup *m){
int i,j;
double *out=alloca(sizeof(double)*winsize);
for(j=0;j<n;j++){
double acc=0.;
memcpy(out,pcm+j*winsize,winsize*sizeof(double));
for(i=0;i<winsize;i++)
out[i]*=window[i];
mdct_forward(m,out,out);
for(i=winsize/10;i<winsize/2;i++)
acc+=fabs(out[i]);
if(deltas[j]<acc)deltas[j]=acc;
}
}
void _ve_envelope_deltas(vorbis_dsp_state *v){
vorbis_info *vi=v->vi;
int step=vi->envelopesa;
int dtotal=v->pcm_current/vi->envelopesa;
int dcurr=v->envelope_current;
int pch;
if(dtotal>dcurr){
double *mult=v->multipliers+dcurr;
memset(mult,0,sizeof(double)*(dtotal-dcurr));
for(pch=0;pch<vi->channels;pch++){
double *pcm=v->pcm[pch]+dcurr*step;
_ve_deltas(mult,pcm,dtotal-dcurr,v->ve.window,v->ve.winlen,&v->ve.mdct);
}
v->envelope_current=dtotal;
}
}
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