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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 1.21.2.2.2.2 2000/09/26 18:45:33 jack Exp $
Preecho calculation.
********************************************************************/
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <math.h>
#include <ogg/ogg.h>
#include "vorbis/codec.h"
#include "os.h"
#include "scales.h"
#include "envelope.h"
#include "misc.h"
/* We use a Chebyshev bandbass for the preecho trigger bandpass; it's
close enough for sample rates 32000-48000 Hz (corner frequencies at
6k/14k assuming sample rate of 44.1kHz) */
/* Digital filter designed by mkfilter/mkshape/gencode A.J. Fisher
Command line: /www/usr/fisher/helpers/mkfilter -Ch \
-6.0000000000e+00 -Bp -o 5 -a 1.3605442177e-01 3.1746031746e-01 -l */
#if 0
static int cheb_bandpass_stages=10;
static float cheb_bandpass_gain=5.589612458e+01;
static float cheb_bandpass_B[]={-1.,0.,5.,0.,-10.,0.,10.,0.,-5.,0.,1};
static float cheb_bandpass_A[]={
-0.1917409386,
0.0078657069,
-0.7126903444,
0.0266343467,
-1.4047174730,
0.0466964232,
-1.9032773429,
0.0451493360,
-1.4471447397,
0.0303413711};
#endif
static int cheb_highpass_stages=10;
static float cheb_highpass_gain= 5.291963434e+01;
/* z^-stage, z^-stage+1... */
static float cheb_highpass_B[]={1,-10,45,-120,210,-252,210,-120,45,-10,1};
static float cheb_highpass_A[]={
-0.1247628029,
0.1334086523,
-0.3997715614,
0.3213011089,
-1.1131924119,
1.7692446626,
-3.6241199038,
4.1950871291,
-4.2771757867,
2.3920318913};
void _ve_envelope_init(envelope_lookup *e,vorbis_info *vi){
int ch=vi->channels;
int window=vi->envelopesa;
int i;
e->winlength=window;
e->minenergy=fromdB(vi->preecho_minenergy);
e->iir=calloc(ch,sizeof(IIR_state));
e->filtered=calloc(ch,sizeof(float *));
e->ch=ch;
e->storage=128;
for(i=0;i<ch;i++){
IIR_init(e->iir+i,cheb_highpass_stages,cheb_highpass_gain,
cheb_highpass_A,cheb_highpass_B);
e->filtered[i]=calloc(e->storage,sizeof(float));
}
drft_init(&e->drft,window);
e->window=malloc(e->winlength*sizeof(float));
/* We just use a straight sin(x) window for this */
for(i=0;i<e->winlength;i++)
e->window[i]=sin((i+.5)/e->winlength*M_PI);
}
void _ve_envelope_clear(envelope_lookup *e){
int i;
for(i=0;i<e->ch;i++){
IIR_clear((e->iir+i));
free(e->filtered[i]);
}
drft_clear(&e->drft);
free(e->window);
free(e->filtered);
memset(e,0,sizeof(envelope_lookup));
}
static float _ve_deltai(envelope_lookup *ve,IIR_state *iir,
float *pre,float *post){
long n2=ve->winlength*2;
long n=ve->winlength;
float *workA=alloca(sizeof(float)*n2),A=0.;
float *workB=alloca(sizeof(float)*n2),B=0.;
long i;
/*_analysis_output("A",granulepos,pre,n,0,0);
_analysis_output("B",granulepos,post,n,0,0);*/
for(i=0;i<n;i++){
workA[i]=pre[i]*ve->window[i];
workB[i]=post[i]*ve->window[i];
}
/*_analysis_output("Awin",granulepos,workA,n,0,0);
_analysis_output("Bwin",granulepos,workB,n,0,0);*/
drft_forward(&ve->drft,workA);
drft_forward(&ve->drft,workB);
/* we want to have a 'minimum bar' for energy, else we're just
basing blocks on quantization noise that outweighs the signal
itself (for low power signals) */
{
float min=ve->minenergy;
for(i=0;i<n;i++){
if(fabs(workA[i])<min)workA[i]=min;
if(fabs(workB[i])<min)workB[i]=min;
}
}
/*_analysis_output("Afft",granulepos,workA,n,0,0);
_analysis_output("Bfft",granulepos,workB,n,0,0);*/
for(i=0;i<n;i++){
A+=workA[i]*workA[i];
B+=workB[i]*workB[i];
}
A=todB(A);
B=todB(B);
return(B-A);
}
long _ve_envelope_search(vorbis_dsp_state *v,long searchpoint){
vorbis_info *vi=v->vi;
envelope_lookup *ve=v->ve;
long i,j;
/* make sure we have enough storage to match the PCM */
if(v->pcm_storage>ve->storage){
ve->storage=v->pcm_storage;
for(i=0;i<ve->ch;i++)
ve->filtered[i]=realloc(ve->filtered[i],ve->storage*sizeof(float));
}
/* catch up the highpass to match the pcm */
for(i=0;i<ve->ch;i++){
float *filtered=ve->filtered[i];
float *pcm=v->pcm[i];
IIR_state *iir=ve->iir+i;
for(j=ve->current;j<v->pcm_current;j++)
filtered[j]=IIR_filter(iir,pcm[j]);
}
ve->current=v->pcm_current;
/* Now search through our cached highpass data for breaking points */
/* starting point */
if(v->W)
j=v->centerW+vi->blocksizes[1]/4-vi->blocksizes[0]/4;
else
j=v->centerW;
while(j+ve->winlength<=v->pcm_current){
for(i=0;i<ve->ch;i++){
float *filtered=ve->filtered[i]+j;
IIR_state *iir=ve->iir+i;
float m=_ve_deltai(ve,iir,filtered-ve->winlength,filtered);
if(m>vi->preecho_thresh){
/*granulepos++;*/
return(0);
}
/*granulepos++;*/
}
j+=vi->blocksizes[0]/2;
if(j>=searchpoint)return(1);
}
return(-1);
}
void _ve_envelope_shift(envelope_lookup *e,long shift){
int i;
for(i=0;i<e->ch;i++)
memmove(e->filtered[i],e->filtered[i]+shift,(e->current-shift)*
sizeof(float));
e->current-=shift;
}
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