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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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