ref: f5a6ef57b3baa4c671defdc987bc0aa583251c58
dir: /rateconv.c/
/**********************************************************************
audio sample rate converter
$Id: rateconv.c,v 1.2 2000/01/31 08:00:38 lenox Exp $
Source file: rateconv.c
Authors:
NM Nikolaus Meine, Uni Hannover (c/o Heiko Purnhagen)
HP Heiko Purnhagen, Uni Hannover <purnhage@tnt.uni-hannover.de>
Changes:
xx-jun-98 NM resamp.c
18-sep-98 HP converted into module
03-aug-99 NM now even faster ...
04-nov-99 NM/HP double ratio, htaps1 /= 2
11-nov-99 HP improved RateConvInit() debuglevel
**********************************************************************/
/*
* Sample-rate converter
*
* Realized in three steps:
*
* 1. Upsampling by factor two while doing appropriate lowpass-filtering.
* This is done by using an FFT-based convolution algorithm with a multi-tap
* Kaiser-windowed lowpass filter.
* If the cotoff-frequency is less than 0.5, only lowpass-filtering without
* the upsampling is done.
* 2. Upsampling by factor 128 using a 15 tap Kaiser-windowed lowpass filter
* (alpha=12.5) and conventional convolution algorithm.
* Two values (the next neighbours) are computed for every sample needed.
* 3. Linear interpolation between the two bounding values.
*
* Stereo and mono data is supported.
* Up- and downsampling of any ratio is possible.
* Input and output file format is Sun-audio.
*
* Written by N.Meine, 1998
*
*/
/* Multi channel data is interleaved: l0 r0 l1 r1 ... */
/* Total number of samples (over all channels) is used. */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "aacenc.h"
#include "rateconv.h"
/* ---------- declarations ---------- */
#ifndef min
#define min(a,b) ((a) < (b) ? (a) : (b))
#endif
#ifndef min
#define max(a,b) ((a) > (b) ? (a) : (b))
#endif
/* ---------- declarations (structures) ---------- */
#define real double /* float seems to be precise enough, but it */
/* doesn't run much faster than double */
typedef struct {
real re,im;
} complex;
struct RCBufStruct /* buffer handle */
{
int numChannel; /* number of channels */
long currentSampleIn; /* number of input samples */
long currentSampleOut; /* number of output samples */
real *wtab;
complex *x;
real *tp1;
real *tp2;
complex *ibuf;
long nfn;
long adv;
long istart;
long numode;
long fm;
double p1;
double d1;
long outSize;
float *out;
};
/* ---------- variables ---------- */
int RCdebugLevel = 0; /* debug level */
#define deftaps1 485
#define ov2exp 7 /* Oversampling exponent in the second step */
#define ov2fac (1<<ov2exp) /* Oversampling factor in the second step */
#define htaps2 7 /* Num. taps of the 2nd filter: 2*htaps2+1 */
#define alpha2 12.5 /* Kaiser-parameter for the second filter */
#define cutoff2 0.97 /* cutoff-frequency for the second filter */
#define cexp (CACHE1-(sizeof(real)==4 ? 3 : 4 ))
#define cache (1<<cexp)
#define pi 3.1415926535897932
#define zpi 6.2831853071795965
/* ---------- local functions ---------- */
void mkeiwutab(real *st,long fn)
{
register int i,k;
register double phi;
for (k=fn; k; k>>=1)
{
phi = zpi/((double) k);
for (i=0; i<k; i++) st[i]=(real) sin(phi*((double) i));
st+=k;
}
}
void r4fftstep(register real *x0,register long n,register real *t)
{
register long n4 = n/4;
register real *x1 = x0+2*n4;
register real *x2 = x1+2*n4;
register real *x3 = x2+2*n4;
register real *y;
register real wr,wi,ar,ai,br,bi,cr,ci,dr,di,hr,hi;
register long i;
if ( n>16 )
{
y=t+6*n4;
r4fftstep(x0,n4,y);
r4fftstep(x1,n4,y);
r4fftstep(x2,n4,y);
r4fftstep(x3,n4,y);
}
else
{
if ( n==8 )
{
for (y=x0; y<x0+16; y+=4)
{
ar=y[0]; ai=y[1];
br=y[2]; bi=y[3];
y[0]=ar+br;
y[1]=ai+bi;
y[2]=ar-br;
y[3]=ai-bi;
}
}
else
{
for (y=x0; y<x0+32; y+=8)
{
ar=y[0]; ai=y[1];
br=y[2]; bi=y[3];
cr=y[4]; ci=y[5];
dr=y[6]; di=y[7];
hr=ar+cr; wr=ar-cr; hi=ai+ci; wi=ai-ci;
ar=br+dr; cr=br-dr; ai=bi+di; ci=bi-di;
y[0]=hr+ar; y[1]=hi+ai;
y[2]=wr+ci; y[3]=wi-cr;
y[4]=hr-ar; y[5]=hi-ai;
y[6]=wr-ci; y[7]=wi+cr;
}
}
}
y=t+n4;
for (i=0; i<n4; i++)
{
ar=x0[0]; ai=x0[1];
wr=y[ i]; wi=t[ i]; hr=x1[0]; hi=x1[1]; br=wr*hr+wi*hi; bi=wr*hi-wi*hr;
wr=y[2*i]; wi=t[2*i]; hr=x2[0]; hi=x2[1]; cr=wr*hr+wi*hi; ci=wr*hi-wi*hr;
wr=y[3*i]; wi=t[3*i]; hr=x3[0]; hi=x3[1]; dr=wr*hr+wi*hi; di=wr*hi-wi*hr;
hr=ar+cr; wr=ar-cr; hi=ai+ci; wi=ai-ci;
ar=br+dr; cr=br-dr; ai=bi+di; ci=bi-di;
x0[0]=hr+ar; x0[1]=hi+ai;
x1[0]=wr+ci; x1[1]=wi-cr;
x2[0]=hr-ar; x2[1]=hi-ai;
x3[0]=wr-ci; x3[1]=wi+cr;
x0+=2; x1+=2; x2+=2; x3+=2;
}
}
void r4ifftstep(register real *x0,register long n,register real *t)
{
register long n4 = n/4;
register real *x1 = x0+2*n4;
register real *x2 = x1+2*n4;
register real *x3 = x2+2*n4;
register real *y;
register real wr,wi,ar,ai,br,bi,cr,ci,dr,di,hr,hi;
register long i;
if ( n>16 )
{
y=t+6*n4;
r4ifftstep(x0,n4,y);
r4ifftstep(x1,n4,y);
r4ifftstep(x2,n4,y);
r4ifftstep(x3,n4,y);
}
else
{
if ( n==8 )
{
for (y=x0; y<x0+16; y+=4)
{
ar=y[0]; ai=y[1];
br=y[2]; bi=y[3];
y[0]=ar+br;
y[1]=ai+bi;
y[2]=ar-br;
y[3]=ai-bi;
}
}
else
{
for (y=x0; y<x0+32; y+=8)
{
ar=y[0]; ai=y[1];
br=y[2]; bi=y[3];
cr=y[4]; ci=y[5];
dr=y[6]; di=y[7];
hr=ar+cr; wr=ar-cr; hi=ai+ci; wi=ai-ci;
ar=br+dr; cr=br-dr; ai=bi+di; ci=bi-di;
y[0]=hr+ar; y[1]=hi+ai;
y[2]=wr-ci; y[3]=wi+cr;
y[4]=hr-ar; y[5]=hi-ai;
y[6]=wr+ci; y[7]=wi-cr;
}
}
}
y=t+n4;
for (i=0; i<n4; i++)
{
ar=x0[0]; ai=x0[1];
wr=y[ i]; wi=t[ i]; hr=x1[0]; hi=x1[1]; br=wr*hr-wi*hi; bi=wr*hi+wi*hr;
wr=y[2*i]; wi=t[2*i]; hr=x2[0]; hi=x2[1]; cr=wr*hr-wi*hi; ci=wr*hi+wi*hr;
wr=y[3*i]; wi=t[3*i]; hr=x3[0]; hi=x3[1]; dr=wr*hr-wi*hi; di=wr*hi+wi*hr;
hr=ar+cr; wr=ar-cr; hi=ai+ci; wi=ai-ci;
ar=br+dr; cr=br-dr; ai=bi+di; ci=bi-di;
x0[0]=hr+ar; x0[1]=hi+ai;
x1[0]=wr-ci; x1[1]=wi+cr;
x2[0]=hr-ar; x2[1]=hi-ai;
x3[0]=wr+ci; x3[1]=wi-cr;
x0+=2; x1+=2; x2+=2; x3+=2;
}
}
void perm4(real *x,long p)
{
register real a,b,c,d;
register long i,j,k,l;
l=1<<(p-1);
for (i=j=0; i<(2<<p); i+=2)
{
if ( j>i )
{
a=x[i]; b=x[i+1]; c=x[j]; d=x[j+1]; x[j]=a; x[j+1]=b; x[i]=c; x[i+1]=d;
}
j+=l;
for (k=l<<2; j&k; k>>=2) j=(j^=k)+(k>>4);
}
}
void perm42(real *x,long p)
{
register real *y,*z;
register long i,n;
n=1<<p;
perm4(x ,p-1);
perm4(x+n,p-1);
y=x+2*n;
z=x+n;
for (i=0; i<n; i+=2)
{
y[2*i ]=x[i ];
y[2*i+1]=x[i+1];
y[2*i+2]=z[i ];
y[2*i+3]=z[i+1];
x[i ]=y[i ];
x[i+1]=y[i+1];
}
for (; i<2*n; i+=2)
{
x[i ]=y[i ];
x[i+1]=y[i+1];
}
}
void r4fft(real *t,real *x,long p)
{
register long n = 1<<p;
if ( p&1 ) perm42(x,p); else perm4(x,p);
r4fftstep(x,n,t);
}
void r4ifft(real *t,real *x,long p)
{
register long n = 1<<p;
if ( p&1 ) perm42(x,p); else perm4(x,p);
r4ifftstep(x,n,t);
}
double bessel(double x)
{
register double p,s,ds,k;
x*=0.5;
k=0.0;
p=s=1.0;
do
{
k+=1.0;
p*=x/k;
ds=p*p;
s+=ds;
}
while ( ds>1.0e-17*s );
return s;
}
void mktp1(complex *y,double fg,double a,long fn,long htaps1)
{
register long i;
register double f,g,x,px;
y[0].re=fg;
y[0].im=0.0;
f=1.0/bessel(a);
g=1.0/(htaps1+0.5);
g*=g;
for (i=1; i<=htaps1; i++)
{
x=(double) i;
px=pi*x;
y[i].re=(real) f*bessel(a*sqrt(1.0-g*x*x))*sin(fg*px)/px;
y[i].im=(real) 0.0;
y[fn-i]=y[i];
}
for (; i<fn-htaps1; i++) y[i].re=y[i].im=0.0;
}
void mktp2(real *y,double fg,double a)
{
register long i;
register double f,g,x,px;
y[0]=fg;
f=1.0/bessel(a);
g=1.0/(((double) ((htaps2+1)*ov2fac))-0.5);
g*=g;
for (i=1; i<(htaps2+1)*ov2fac; i++)
{
x=(double) i;
px=(pi/ov2fac)*x;
y[i]=(real) f*bessel(a*sqrt(1.0-g*x*x))*sin(fg*px)/px;
}
for (; i<(htaps2+2)*ov2fac; i++) y[i]=0.0;
}
void ctp2_m(real *x,double p,real *k,float **out)
{
register long n,i,j;
register double h,l,r;
register real *ka,*kb;
register real *xa,*xb;
h=ov2fac*p;
i=(long) h;
h-=(double) i;
j=i&(ov2fac-1); i>>=ov2exp;
l=r=0.0;
ka=k+j; kb=k+ov2fac-j;
i<<=1;
xa=x+i; xb=x+i+2;
n=htaps2+1;
do
{
l+=xa[0]*ka[ 0] + xb[0]*kb[ 0];
r+=xa[0]*ka[ 1] + xb[0]*kb[-1];
ka+=ov2fac;
kb+=ov2fac;
xa-=2;
xb+=2;
}
while (--n);
*(*out)++ = (float) (l+h*(r-l));
}
void ctp2_s(complex *x,double p,real *k,float **out)
{
register long n,i,j;
register double h,l0,l1,r0,r1;
register real *ka,*kb;
register complex *xa,*xb;
h=ov2fac*p;
i=(long) h;
h-=(double) i;
j=i&(ov2fac-1); i>>=ov2exp;
l0=l1=r0=r1=0.0;
ka=k+j; kb=k+ov2fac-j;
xa=x+i; xb=x+i+1;
n=htaps2+1;
do
{
l0+=xa[0].re*ka[ 0] + xb[0].re*kb[ 0];
l1+=xa[0].im*ka[ 0] + xb[0].im*kb[ 0];
r0+=xa[0].re*ka[ 1] + xb[0].re*kb[-1];
r1+=xa[0].im*ka[ 1] + xb[0].im*kb[-1];
ka+=ov2fac;
kb+=ov2fac;
xa--;
xb++;
}
while (--n);
*(*out)++ = (float) (l0+h*(r0-l0));
*(*out)++ = (float) (l1+h*(r1-l1));
}
void ctp1_1(complex *x,real *tp1,real *wtab,long fm)
{
register long i,fn2;
fn2=1<<(fm-1);
r4fft(wtab,(real *) x,fm);
for (i=0; i<fn2; i++)
{
x[i+fn2].re*=tp1[fn2-i];
x[i+fn2].im*=tp1[fn2-i];
x[i ].re*=tp1[i ];
x[i ].im*=tp1[i ];
}
r4ifft(wtab,(real *) x,fm);
}
void ctp1_2(complex *x,real *tp1,real *wtab,long fm)
{
register long i,fn2;
fn2=1<<(fm-1);
r4fft(wtab+(1<<fm),(real *) x,fm-1);
for (i=0; i<fn2; i++)
{
x[i+fn2].re=x[i].re*tp1[fn2-i];
x[i+fn2].im=x[i].im*tp1[fn2-i];
x[i].re*=tp1[i];
x[i].im*=tp1[i];
}
r4ifft(wtab,(real *) x,fm);
}
/* ---------- functions ---------- */
/* RateConvInit() */
/* Init audio sample rate conversion. */
RCBuf *RateConvInit (
int debugLevel, /* in: debug level */
/* 0=off 1=basic 2=full */
double ratio, /* in: outputRate / inputRate */
int numChannel, /* in: number of channels */
int htaps1, /* in: num taps */
/* -1 = auto */
float a1, /* in: alpha for Kaiser window */
/* -1 = auto */
float fc, /* in: 6dB cutoff freq / input bandwidth */
/* -1 = auto */
float fd, /* in: 100dB cutoff freq / input bandwidth */
/* -1 = auto */
long *numSampleIn) /* out: num input samples / frame */
/* returns: */
/* buffer (handle) */
/* or NULL if error */
{
real *wtab;
complex *x;
real *tp1;
real *tp2;
complex *ibuf;
long nfn;
long adv;
long istart;
long numode;
long fm;
double p1;
double d1;
double sf2;
double trw2;
long fn;
long fn2;
long i;
double h;
double a;
RCBuf *buf;
RCdebugLevel = debugLevel;
if (RCdebugLevel)
printf("RateConvInit: debugLevel=%d ratio=%f numChannel=%d\n"
"htaps1=%d a1=%f fc=%f fd=%f\n",
RCdebugLevel,ratio,numChannel,htaps1,a1,fc,fd);
buf=(RCBuf*)malloc(sizeof(RCBuf));
// if (!(buf=(RCBuf*)malloc(sizeof(RCBuf))))
// CommonExit(-1,"RateConvInit: Can not allocate memory");
buf->currentSampleIn = 0;
buf->currentSampleOut = 0;
buf->numChannel = numChannel;
if (htaps1<0)
htaps1 = deftaps1;
htaps1 /= 2; /* NM 991104 */
if (a1<0)
a1 = 10.0;
numode = 0;
for (fm=2; (1<<fm)<8*htaps1; fm+=2);
fn=1<<fm;
fn2=fn/2;
wtab=(real *) malloc((4*fn + fn2+1 + (htaps2+2)*ov2fac)*sizeof(real));
// if (!(wtab=
// (real *) malloc((4*fn + fn2+1 + (htaps2+2)*ov2fac)*sizeof(real))))
// CommonExit(-1,"RateConvInit: Can not allocate memory");
x=((complex *) wtab)+fn;
tp1=(real *) (x+fn);
tp2=tp1+fn2+1;
mkeiwutab(wtab,fn);
mktp1(x,0.5,a1,fn,htaps1);
r4fft(wtab,(real *) x,fm);
h=x[0].re*x[0].re*1.0e-10;
for (i=fn/2; x[i].re*x[i].re<h; i--);
trw2=((double) (i-(fn2/2)))/((double) (fn2/2));
sf2 = ratio;
if ( sf2<0.0 ) sf2=1.0;
d1=1.0/sf2;
p1=htaps1+htaps2+2; /* delay compensation */
if ( fc<0.0 )
{
if ( fd<0.0 )
{
fc=1.0/d1-trw2;
if ( fc<0.5-0.5*trw2 ) { numode=1; fc=2.0/d1-trw2; }
if ( fc>1.0-trw2 ) fc=1.0-trw2;
}
else
{
fc=fd-trw2;
if ( fd<=0.5 ) { numode=1; fc=2.0*fd-trw2; }
}
}
else
{
if ( fc<0.5-trw2 ) { numode=1; fc+=fc; }
}
if ( fc>2.0 ) fc=2.0;
if ( fc<=0.0 ) {
// CommonWarning("RateConvInit: cutoff frequency to low: %f %f %f\n",
// fc,fd,trw2);
free(wtab);
free(buf);
return NULL;
}
nfn=fn;
adv=fn-2*(htaps1+htaps2+2);
istart=htaps1+htaps2+2;
if ( !numode ) { nfn>>=1; adv>>=1; d1+=d1; }
mktp1(x,0.5*fc,a1,fn,htaps1);
r4fft(wtab,(real *) x,fm);
a=1.0/((double) (((1+numode)*fn2)));
for (i=0; i<=fn2 ; i++) tp1[i]=a*x[i].re;
mktp2(tp2,cutoff2,alpha2);
*numSampleIn = 2*adv;
buf->outSize = (long)((2*adv+4)*ratio+4);
buf->out=(float*)malloc(buf->outSize*sizeof(float));
// if (!(buf->out=(float*)malloc(buf->outSize*sizeof(float))))
// CommonExit(-1,"RateConvInit: Can not allocate memory");
ibuf = (complex *) malloc((nfn-adv)*sizeof(complex));
// if (!(ibuf = (complex *) malloc((nfn-adv)*sizeof(complex))))
// CommonExit(-1,"RateConvInit: Can not allocate memory");
if ( buf->numChannel==1 ) {
/* ibuf[?].im not used ... */
for (i=0; i<(nfn-adv)/2; i++)
ibuf[i].re=0.0;
for ( ; i<(nfn-adv) ; i++)
ibuf[i].re=0.0;
/* ibuf[i].re=(real) dataIn[idxIn++]; */
}
else {
for (i=0; i< (nfn-adv); i++)
((real *) ibuf)[i]=0.0;
for ( ; i<2*(nfn-adv); i++)
((real *) ibuf)[i]=0.0;
/* ((real *) ibuf)[i]=(real) dataIn[idxIn++]; */
}
if (RCdebugLevel)
printf("RateConvInit: inSize=%ld outSize=%ld\n"
" output/input ratio : %8.2f\n"
" cutoff frequency : %10.4f\n"
" Kaiser parameter : %10.4f\n"
" filter 1 taps : %5li\n"
" filter 1 transition: %10.4f\n"
" FFT length : %5li\n"
" oversampling factor: %5li\n",
2*adv,buf->outSize,
sf2,fc/(1+numode),a1,(long)2*htaps1+1,0.5*trw2,
fn,ov2fac*(2-numode));
buf->wtab = wtab;
buf->x= x;
buf->tp1 = tp1;
buf->tp2 = tp2;
buf->ibuf = ibuf;
buf->nfn = nfn;
buf->adv = adv;
buf->istart = istart;
buf->numode = numode;
buf->fm = fm;
buf->p1 = p1;
buf->d1 = d1;
return buf;
}
/* RateConv() */
/* Convert sample rate for one frame of audio data. */
long RateConv (
RCBuf *buf, /* in: buffer (handle) */
short *dataIn, /* in: input data[] */
long numSampleIn, /* in: number of input samples */
float **dataOut) /* out: output data[] */
/* returns: */
/* numSampleOut */
{
real *wtab = buf->wtab;
complex *x = buf->x;
real *tp1 = buf->tp1;
real *tp2 = buf->tp2;
complex *ibuf = buf->ibuf;
long nfn = buf->nfn;
long adv = buf->adv;
long istart = buf->istart;
long numode = buf->numode;
long fm = buf->fm;
double p1 = buf->p1;
double d1 = buf->d1;
long i;
double p,h;
long idxIn,numOut;
float *out;
if (RCdebugLevel)
printf("RateConv: numSampleIn=%ld\n",numSampleIn);
// if (numSampleIn != 2*adv)
// CommonExit(-1,"RateConv: wrong numSampleIn");
idxIn = 0;
out = buf->out;
if ( buf->numChannel==1 ) {
/* ibuf[?].im not used ... */
for (i=0 ; i<nfn-adv; i++)
x[i].re=ibuf[i].re;
for ( ; i< adv; i++)
x[i].re=(real) dataIn[idxIn++];
for ( ; i< nfn; i++)
x[i].re=x[i-adv].im=(real) dataIn[idxIn++];
for (i=nfn-adv; i< adv; i++)
x[i].im=(real) dataIn[idxIn++];
for ( ; i< nfn; i++)
x[i].im=ibuf[i-adv].re=(real) dataIn[idxIn++];
if ( numode )
ctp1_1(x,tp1,wtab,fm);
else
ctp1_2(x,tp1,wtab,fm);
i=adv;
h=(double) ((2*i)>>numode);
for (p=p1; p<h; p+=d1) ctp2_m(&(x[istart].re),p,tp2,&out);
p1=p-h;
i=adv;
h=(double) ((2*i)>>numode);
for (p=p1; p<h; p+=d1) ctp2_m(&(x[istart].im),p,tp2,&out);
p1=p-h;
}
else {
for (i=0; i<nfn-adv; i++)
x[i]=ibuf[i];
for (; i<adv; i++) {
x[i].re=(real) dataIn[idxIn++];
x[i].im=(real) dataIn[idxIn++];
}
for (; i<nfn; i++) {
x[i].re=ibuf[i-adv].re=(real) dataIn[idxIn++];
x[i].im=ibuf[i-adv].im=(real) dataIn[idxIn++];
}
if ( numode )
ctp1_1(x,tp1,wtab,fm);
else
ctp1_2(x,tp1,wtab,fm);
i=2*adv;
h=(double) (i>>numode);
for (p=p1; p<h; p+=d1) ctp2_s(x+istart,p,tp2,&out);
p1=p-h;
}
buf->p1 = p1;
*dataOut = buf->out;
numOut = out - buf->out;
// if (numOut > buf->outSize)
// CommonExit(-1,"RateConv: output buffer size troubles");
buf->currentSampleIn += 2*adv;
buf->currentSampleOut += numOut;
return numOut;
}
/* RateConvFree() */
/* Free RateConv buffers. */
void RateConvFree (
RCBuf *buf) /* in: buffer (handle) */
{
if (RCdebugLevel)
printf("RateConvFree: sampleIn=%ld sampleOut=%ld\n",
buf->currentSampleIn,buf->currentSampleOut);
free(buf->out);
free(buf->wtab);
free(buf->ibuf);
free(buf);
}
/* end of rateconv.c */