ref: 4f1e884b74dcb205d224c70c1b2cd31ffda49d6d
dir: /winswitch.c/
/*
* Window switching module
* Most of this has been taken from NTT source code in the MPEG-4
* Verification Model.
*
* TODO:
* - better multi-channel support
*/
#include <math.h>
#include "tf_main.h"
#include "winswitch.h"
#define ntt_N_SUP_MAX 2
int num_channel;
int winSwitch(/* Input */
double sig[], /* input signal */
/* Output */
enum WINDOW_TYPE *w_type, /* code index for block type */
/* Control */
int InitFlag)/* initialization flag */
{
/*--- Variables ---*/
int s_attack;
int ratio;
/*--- A.Jin 1997.10.19 ---*/
ratio = checkAttack(sig, &s_attack, InitFlag);
getWindowType( s_attack, w_type, InitFlag );
return ratio;
}
void getWindowType(int flag, /* Input : trigger for short block length */
enum WINDOW_TYPE *w_type, /* Output : code index for block type */
int InitFlag ) /* Control : initialization flag */
{
static int w_type_pre;
static int flag_pre;
if ( InitFlag ){
flag_pre = 0;
w_type_pre = ONLY_LONG_WINDOW;
}
if (InitFlag){
if (flag) *w_type = ONLY_SHORT_WINDOW;
else *w_type = ONLY_LONG_WINDOW;
}
else{
switch( w_type_pre ){
case ONLY_LONG_WINDOW:
if ( flag ) *w_type = LONG_SHORT_WINDOW;
else *w_type = ONLY_LONG_WINDOW;
break;
case LONG_SHORT_WINDOW:
*w_type = ONLY_SHORT_WINDOW;
break;
case SHORT_LONG_WINDOW:
if ( flag ) *w_type = LONG_SHORT_WINDOW;
else *w_type = ONLY_LONG_WINDOW;
break;
case ONLY_SHORT_WINDOW:
if (flag || flag_pre) *w_type = ONLY_SHORT_WINDOW;
else *w_type = SHORT_LONG_WINDOW;
}
}
w_type_pre = *w_type;
flag_pre = flag;
}
#define ST_CHKATK (BLOCK_LEN_LONG/2+BLOCK_LEN_SHORT/2)
#define N_BLK_MAX 4096
#define N_SFT_MAX 256
#define N_LPC_MAX 2
__inline void ZeroMem(int n, double xx[])
{
int i = n;
while(i-- != 0)
*(xx++) = 0.0;
}
void LagWindow(/* Output */
double wdw[], /* lag window data */
/* Input */
int n, /* dimension of wdw[.] */
double h) /* ratio of window half value band width to sampling frequency */
{
int i;
double pi=3.14159265358979323846264338327959288419716939;
double a,b,w;
if(h<=0.0) for(i=0;i<=n;i++) wdw[i]=1.0;
else
{
a=log(0.5)*0.5/log(cos(0.5*pi*h));
a=(double)((int)a);
w=1.0; b=a; wdw[0]=1.0;
for(i=1;i<=n;i++)
{
b+=1.0; w*=a/b; wdw[i]=w; a-=1.0;
}
}
}
void HammingWindow(/* Output */
double wdw[], /* Hamming window data */
int n) /* window length */
{
int i;
double d,pi=3.14159265358979323846264338327950288419716939;
if(n>0)
{
d=2.0*pi/n;
for(i=0;i<n;i++)
wdw[i]=0.54-0.46*cos(d*i);
}
}
__inline void ntt_cutfr(int st, /* Input --- Start point */
int len, /* Input --- Block length */
int ich, /* Input --- Channel number */
double frm[], /* Input --- Input frame */
double buf[]) /* Output --- Output data buffer */
{
/*--- Variables ---*/
int stb, sts, edb, nblk, iblk, ibuf, ifrmb, ifrms;
stb = (st/BLOCK_LEN_LONG)*num_channel + ich; /* start block */
sts = st % BLOCK_LEN_LONG; /* start sample */
edb = ((st+len)/BLOCK_LEN_LONG)*num_channel + ich; /* end block */
nblk = (edb-stb)/num_channel; /* number of overflow */
ibuf=0; ifrmb=stb; ifrms=sts;
for ( iblk=0; iblk<nblk; iblk++ ){
while( ifrms < BLOCK_LEN_LONG ) buf[ibuf++] = frm[(ifrms++)+ifrmb*BLOCK_LEN_LONG];
ifrms = 0;
ifrmb += num_channel;
}
while( ibuf < len )
buf[ibuf++] = frm[(ifrms++)+ifrmb*BLOCK_LEN_LONG];
}
__inline void CopyMem(int n, double xx[], double yy[])
{
int i = n;
if (i <= 0)
return;
do {
*(yy++) = *(xx++);
} while(--i);
}
__inline double DotProd(/* Input */
int n, /* dimension of data */
double xx[],
double yy[])
{
int i;
double s;
s=0.0;
for(i=0;i<n;i++)
s+=xx[i]*yy[i];
return(s);
}
__inline void ntt_mulddd(/* Input */
int n, /* dimension of data */
double xx[],
double yy[],
/* Output */
double zz[])
{
int i;
for (i=0; i<n; i++ )
zz[i] = xx[i]*yy[i];
}
__inline void AutoCorr(double *sig, /* Input : signal sample sequence */
int n, /* Input : length of sample sequence*/
double *_pow,/* Output : power */
double cor[],/* Output : autocorrelation coefficients */
int p)
{
int k;
register double sqsum,c, dsqsum;
if (n>0) {
sqsum = DotProd(n, sig, sig)+1.e-35;
dsqsum = 1./sqsum;
k=p;
do {
c = DotProd(n-k, sig, sig+k);
cor[k] = c*dsqsum;
}while(--k);
}
*_pow = (sqsum-1.e-35)/(double)n;
}
__inline void Corr2Ref(int p, /* Input : LPC analysis order */
double cor[], /* Input : correlation coefficients */
double alf[], /* Output : linear predictive coefficients */
double ref[], /* Output : reflection coefficients */
double *resid_) /* Output : normalized residual power */
{
int i,j,k;
double resid,r,a;
if(p>0) {
ref[1]=cor[1];
alf[1]= -ref[1];
resid=(1.0-ref[1])*(1.0+ref[1]);
for(i=2;i<=p;i++) {
r=cor[i];
for(j=1;j<i;j++)
r+=alf[j]*cor[i-j];
alf[i]= -(ref[i]=(r/=resid));
j=0; k=i;
while(++j<=--k) {
a=alf[j];
alf[j]-=r*alf[k];
if(j<k) alf[k]-=r*a;
}
resid*=(1.0-r)*(1.0+r);
}
*resid_=resid;
}
else
*resid_=1.0;
}
int checkAttack(double in[], /* Input signal */
int *flag, /* flag for attack */
int InitFlag) /* Initialization Flag */
{
/*--- Variables ---*/
int n_div, iblk, ismp, ich;
double bufin[N_SFT_MAX];
static double sig[ntt_N_SUP_MAX][N_BLK_MAX+N_LPC_MAX];
double wsig[N_BLK_MAX];
static double wdw[N_BLK_MAX];
static double wlag[N_LPC_MAX+1];
double cor[N_LPC_MAX+1],ref[N_LPC_MAX+1],alf[N_LPC_MAX+1];
static double prev_alf[ntt_N_SUP_MAX][N_LPC_MAX+1];
double resid, wpowfr;
double long_power;
double synth, resid2;
static int N_BLK, N_SFT, S_POW, L_POW, N_LPC;
double ratio, sum, product;
/*--- Initialization ---*/
if ( InitFlag ){
/* Set parameters */
N_BLK = BLOCK_LEN_LONG;
N_SFT = BLOCK_LEN_SHORT;
S_POW = BLOCK_LEN_SHORT;
L_POW = BLOCK_LEN_LONG;
N_LPC = 1;
/* clear buffers */
for ( ich=0; ich<num_channel; ich++ ){
ZeroMem( N_LPC+N_BLK, sig[ich] );
ZeroMem( N_LPC+1, prev_alf[ich] );
}
/* set windows */
LagWindow( wlag, N_LPC, 0.02 );
HammingWindow( wdw, N_BLK );
}
n_div = BLOCK_LEN_LONG/N_SFT;
*flag = 0;
sum=0.0;
product=1.0;
for ( ich=0; ich<num_channel; ich++ ){
for ( iblk=0; iblk<n_div; iblk++ ){
ntt_cutfr( ST_CHKATK+iblk*N_SFT, N_SFT, ich, in, bufin );
CopyMem(N_SFT,bufin,&sig[ich][N_LPC+N_BLK-N_SFT]);
/*--- Calculate long power ---*/
long_power =
(DotProd( L_POW, &sig[ich][N_BLK-L_POW], &sig[ich][N_BLK-L_POW] )+0.1)
/ L_POW;
long_power = sqrt(long_power);
/*--- Calculate alpha parameter ---*/
ntt_mulddd( N_BLK, &sig[ich][N_LPC], wdw, wsig );
AutoCorr( wsig, N_BLK, &wpowfr, cor, N_LPC ); cor[0] = 1.0;
ntt_mulddd( N_LPC+1, cor, wlag, cor );
Corr2Ref( N_LPC, cor, alf, ref, &resid );
/*--- Get residual signal and its power ---*/
resid2 = 0.;
for ( ismp=N_BLK-S_POW; ismp<N_BLK; ismp++ ){
synth = sig[ich][ismp]+
prev_alf[ich][1]*sig[ich][ismp-1];
resid2 += synth*synth;
}
resid2 /= long_power;
resid2 = sqrt(resid2);
sum += resid2+0.0001;
product *= (resid2+0.0001);
CopyMem( N_LPC, &alf[1], &prev_alf[ich][1] );
CopyMem( N_BLK-N_SFT, &sig[ich][N_LPC+N_SFT], &sig[ich][N_LPC] );
}
}
/* ratio = sum/(n_div*num_channel)/pow(product, 1./(double)(n_div*num_channel)); */
/* This below is a bit different than the commented line above here,
but I like it better this way, because it gives higher values,
that are better to tune. */
ratio = pow(product, 1./(double)(n_div*num_channel));
ratio = (n_div*num_channel)/ratio;
ratio = sum/ratio;
if(ratio > 8000) {
*flag = 1;
} else {
*flag = 0;
}
return (int)(ratio+0.5);
}
void winSwitchInit(int max_ch)
{
num_channel = max_ch;
}