ref: 8a0e3345c6cd8904923cf58c0bbd12ac027ec839
dir: /libfaac/psych.c/
/*
* FAAC - Freeware Advanced Audio Coder
* Copyright (C) 2001 Menno Bakker
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Id: psych.c,v 1.14 2001/09/28 18:36:06 menno Exp $
*/
#include <stdlib.h>
#include <memory.h>
#include <math.h>
#if defined(_DEBUG)
#include <stdio.h>
#endif
#include "psych.h"
#include "coder.h"
#include "fft.h"
#include "util.h"
void PsyInit(GlobalPsyInfo *gpsyInfo, PsyInfo *psyInfo, unsigned int numChannels,
unsigned int sampleRate, int *cb_width_long, int num_cb_long,
int *cb_width_short, int num_cb_short)
{
unsigned int channel;
int i, j, b, bb, high, low, size;
double tmpx,tmpy,tmp,x,b1,b2;
double bval[MAX_SCFAC_BANDS];
gpsyInfo->ath = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
gpsyInfo->athS = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
gpsyInfo->rnorm = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
gpsyInfo->rnormS = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
gpsyInfo->mld = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
gpsyInfo->mldS = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
gpsyInfo->hannWindow = (double*)AllocMemory(2*BLOCK_LEN_LONG*sizeof(double));
gpsyInfo->hannWindowS = (double*)AllocMemory(2*BLOCK_LEN_SHORT*sizeof(double));
for(i = 0; i < BLOCK_LEN_LONG*2; i++)
gpsyInfo->hannWindow[i] = 0.5 * (1-cos(2.0*M_PI*(i+0.5)/(BLOCK_LEN_LONG*2)));
for(i = 0; i < BLOCK_LEN_SHORT*2; i++)
gpsyInfo->hannWindowS[i] = 0.5 * (1-cos(2.0*M_PI*(i+0.5)/(BLOCK_LEN_SHORT*2)));
gpsyInfo->sampleRate = (double)sampleRate;
size = BLOCK_LEN_LONG;
for (channel = 0; channel < numChannels; channel++) {
psyInfo[channel].size = size;
psyInfo[channel].lastPe = 0.0;
psyInfo[channel].lastEnr = 0.0;
psyInfo[channel].threeInARow = 0;
psyInfo[channel].cw = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].maskThr = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].maskEn = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].maskThrNext = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].maskEnNext = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].maskThrMS = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].maskEnMS = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].maskThrNextMS = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].maskEnNextMS = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].prevSamples = (double*)AllocMemory(size*sizeof(double));
memset(psyInfo[channel].prevSamples, 0, size*sizeof(double));
psyInfo[channel].lastNb = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].lastNbMS = (double*)AllocMemory(size*sizeof(double));
for (j = 0; j < size; j++) {
psyInfo[channel].lastNb[j] = 2.;
psyInfo[channel].lastNbMS[j] = 2.;
}
psyInfo[channel].fftMagPlus2 = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftMagPlus1 = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftMag = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftMagMin1 = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftMagMin2 = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftPhPlus2 = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftPhPlus1 = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftPh = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftPhMin1 = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftPhMin2 = (double*)AllocMemory(size*sizeof(double));
}
size = BLOCK_LEN_SHORT;
for (channel = 0; channel < numChannels; channel++) {
psyInfo[channel].sizeS = size;
psyInfo[channel].prevSamplesS = (double*)AllocMemory(size*sizeof(double));
memset(psyInfo[channel].prevSamplesS, 0, size*sizeof(double));
for (j = 0; j < 8; j++) {
psyInfo[channel].cwS[j] = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].maskThrS[j] = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].maskEnS[j] = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].maskThrNextS[j] = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].maskEnNextS[j] = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].maskThrSMS[j] = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].maskEnSMS[j] = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].maskThrNextSMS[j] = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].maskEnNextSMS[j] = (double*)AllocMemory(MAX_SCFAC_BANDS*sizeof(double));
psyInfo[channel].fftMagPlus2S[j] = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftMagPlus1S[j] = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftMagS[j] = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftMagMin1S[j] = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftPhPlus2S[j] = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftPhPlus1S[j] = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftPhS[j] = (double*)AllocMemory(size*sizeof(double));
psyInfo[channel].fftPhMin1S[j] = (double*)AllocMemory(size*sizeof(double));
}
}
size = BLOCK_LEN_LONG;
high = 0;
for(b = 0; b < num_cb_long; b++) {
low = high;
high += cb_width_long[b];
bval[b] = 0.5 * (freq2bark(gpsyInfo->sampleRate*low/(2*size)) +
freq2bark(gpsyInfo->sampleRate*(high-1)/(2*size)));
}
for(b = 0; b < num_cb_long; b++) {
b2 = bval[b];
for(bb = 0; bb < num_cb_long; bb++) {
b1 = bval[bb];
if (b>=bb) tmpx = (b2 - b1)*3.0;
else tmpx = (b2 - b1)*1.5;
if(tmpx>=0.5 && tmpx<=2.5)
{
tmp = tmpx - 0.5;
x = 8.0 * (tmp*tmp - 2.0 * tmp);
}
else x = 0.0;
tmpx += 0.474;
tmpy = 15.811389 + 7.5*tmpx - 17.5*sqrt(1.0+tmpx*tmpx);
if (tmpy <= -100.0) gpsyInfo->spreading[b][bb] = 0.0;
else gpsyInfo->spreading[b][bb] = exp((x + tmpy)*0.2302585093);
}
}
for( b = 0; b < num_cb_long; b++){
tmp = 0.0;
for( bb = 0; bb < num_cb_long; bb++)
tmp += gpsyInfo->spreading[bb][b];
gpsyInfo->rnorm[b] = 1.0/tmp;
}
j = 0;
for( b = 0; b < num_cb_long; b++){
gpsyInfo->ath[b] = 1.e37;
for (bb = 0; bb < cb_width_long[b]; bb++, j++) {
double freq = gpsyInfo->sampleRate*j/(1000.0*2*size);
double level;
level = ATHformula(freq*1000) - 20;
level = pow(10., 0.1*level);
level *= cb_width_long[b];
if (level < gpsyInfo->ath[b])
gpsyInfo->ath[b] = level;
}
}
low = 0;
for (b = 0; b < num_cb_long; b++) {
tmp = freq2bark(gpsyInfo->sampleRate*low/(2*size));
tmp = (min(tmp, 15.5)/15.5);
gpsyInfo->mld[b] = pow(10.0, 1.25*(1-cos(M_PI*tmp))-2.5);
low += cb_width_long[b];
}
size = BLOCK_LEN_SHORT;
high = 0;
for(b = 0; b < num_cb_short; b++) {
low = high;
high += cb_width_short[b];
bval[b] = 0.5 * (freq2bark(gpsyInfo->sampleRate*low/(2*size)) +
freq2bark(gpsyInfo->sampleRate*(high-1)/(2*size)));
}
for(b = 0; b < num_cb_short; b++) {
b2 = bval[b];
for(bb = 0; bb < num_cb_short; bb++) {
b1 = bval[bb];
if (b>=bb) tmpx = (b2 - b1)*3.0;
else tmpx = (b2 - b1)*1.5;
if(tmpx>=0.5 && tmpx<=2.5)
{
tmp = tmpx - 0.5;
x = 8.0 * (tmp*tmp - 2.0 * tmp);
}
else x = 0.0;
tmpx += 0.474;
tmpy = 15.811389 + 7.5*tmpx - 17.5*sqrt(1.0+tmpx*tmpx);
if (tmpy <= -100.0) gpsyInfo->spreadingS[b][bb] = 0.0;
else gpsyInfo->spreadingS[b][bb] = exp((x + tmpy)*0.2302585093);
}
}
j = 0;
for( b = 0; b < num_cb_short; b++){
gpsyInfo->athS[b] = 1.e37;
for (bb = 0; bb < cb_width_short[b]; bb++, j++) {
double freq = gpsyInfo->sampleRate*j/(1000.0*2*size);
double level;
level = ATHformula(freq*1000) - 20;
level = pow(10., 0.1*level);
level *= cb_width_short[b];
if (level < gpsyInfo->athS[b])
gpsyInfo->athS[b] = level;
}
}
for( b = 0; b < num_cb_short; b++){
tmp = 0.0;
for( bb = 0; bb < num_cb_short; bb++)
tmp += gpsyInfo->spreadingS[bb][b];
gpsyInfo->rnormS[b] = 1.0/tmp;
}
low = 0;
for (b = 0; b < num_cb_short; b++) {
tmp = freq2bark(gpsyInfo->sampleRate*low/(2*size));
tmp = (min(tmp, 15.5)/15.5);
gpsyInfo->mldS[b] = pow(10.0, 1.25*(1-cos(M_PI*tmp))-2.5);
low += cb_width_short[b];
}
}
void PsyEnd(GlobalPsyInfo *gpsyInfo, PsyInfo *psyInfo, unsigned int numChannels)
{
unsigned int channel;
int j;
if (gpsyInfo->ath) FreeMemory(gpsyInfo->ath);
if (gpsyInfo->athS) FreeMemory(gpsyInfo->athS);
if (gpsyInfo->rnorm) FreeMemory(gpsyInfo->rnorm);
if (gpsyInfo->rnormS) FreeMemory(gpsyInfo->rnormS);
if (gpsyInfo->mld) FreeMemory(gpsyInfo->mld);
if (gpsyInfo->mldS) FreeMemory(gpsyInfo->mldS);
if (gpsyInfo->hannWindow) FreeMemory(gpsyInfo->hannWindow);
if (gpsyInfo->hannWindowS) FreeMemory(gpsyInfo->hannWindowS);
for (channel = 0; channel < numChannels; channel++) {
if (psyInfo[channel].prevSamples) FreeMemory(psyInfo[channel].prevSamples);
if (psyInfo[channel].cw) FreeMemory(psyInfo[channel].cw);
if (psyInfo[channel].maskThr) FreeMemory(psyInfo[channel].maskThr);
if (psyInfo[channel].maskEn) FreeMemory(psyInfo[channel].maskEn);
if (psyInfo[channel].maskThrNext) FreeMemory(psyInfo[channel].maskThrNext);
if (psyInfo[channel].maskEnNext) FreeMemory(psyInfo[channel].maskEnNext);
if (psyInfo[channel].maskThrMS) FreeMemory(psyInfo[channel].maskThrMS);
if (psyInfo[channel].maskEnMS) FreeMemory(psyInfo[channel].maskEnMS);
if (psyInfo[channel].maskThrNextMS) FreeMemory(psyInfo[channel].maskThrNextMS);
if (psyInfo[channel].maskEnNextMS) FreeMemory(psyInfo[channel].maskEnNextMS);
if (psyInfo[channel].lastNb) FreeMemory(psyInfo[channel].lastNb);
if (psyInfo[channel].lastNbMS) FreeMemory(psyInfo[channel].lastNbMS);
if (psyInfo[channel].fftMagPlus2) FreeMemory(psyInfo[channel].fftMagPlus2);
if (psyInfo[channel].fftMagPlus1) FreeMemory(psyInfo[channel].fftMagPlus1);
if (psyInfo[channel].fftMag) FreeMemory(psyInfo[channel].fftMag);
if (psyInfo[channel].fftMagMin1) FreeMemory(psyInfo[channel].fftMagMin1);
if (psyInfo[channel].fftMagMin2) FreeMemory(psyInfo[channel].fftMagMin2);
if (psyInfo[channel].fftPhPlus2) FreeMemory(psyInfo[channel].fftPhPlus2);
if (psyInfo[channel].fftPhPlus1) FreeMemory(psyInfo[channel].fftPhPlus1);
if (psyInfo[channel].fftPh) FreeMemory(psyInfo[channel].fftPh);
if (psyInfo[channel].fftPhMin1) FreeMemory(psyInfo[channel].fftPhMin1);
if (psyInfo[channel].fftPhMin2) FreeMemory(psyInfo[channel].fftPhMin2);
}
for (channel = 0; channel < numChannels; channel++) {
if(psyInfo[channel].prevSamplesS) FreeMemory(psyInfo[channel].prevSamplesS);
for (j = 0; j < 8; j++) {
if (psyInfo[channel].cwS[j]) FreeMemory(psyInfo[channel].cwS[j]);
if (psyInfo[channel].maskThrS[j]) FreeMemory(psyInfo[channel].maskThrS[j]);
if (psyInfo[channel].maskEnS[j]) FreeMemory(psyInfo[channel].maskEnS[j]);
if (psyInfo[channel].maskThrNextS[j]) FreeMemory(psyInfo[channel].maskThrNextS[j]);
if (psyInfo[channel].maskEnNextS[j]) FreeMemory(psyInfo[channel].maskEnNextS[j]);
if (psyInfo[channel].maskThrSMS[j]) FreeMemory(psyInfo[channel].maskThrSMS[j]);
if (psyInfo[channel].maskEnSMS[j]) FreeMemory(psyInfo[channel].maskEnSMS[j]);
if (psyInfo[channel].maskThrNextSMS[j]) FreeMemory(psyInfo[channel].maskThrNextSMS[j]);
if (psyInfo[channel].maskEnNextSMS[j]) FreeMemory(psyInfo[channel].maskEnNextSMS[j]);
if (psyInfo[channel].fftMagPlus2S[j]) FreeMemory(psyInfo[channel].fftMagPlus2S[j]);
if (psyInfo[channel].fftMagPlus1S[j]) FreeMemory(psyInfo[channel].fftMagPlus1S[j]);
if (psyInfo[channel].fftMagS[j]) FreeMemory(psyInfo[channel].fftMagS[j]);
if (psyInfo[channel].fftMagMin1S[j]) FreeMemory(psyInfo[channel].fftMagMin1S[j]);
if (psyInfo[channel].fftPhPlus2S[j]) FreeMemory(psyInfo[channel].fftPhPlus2S[j]);
if (psyInfo[channel].fftPhPlus1S[j]) FreeMemory(psyInfo[channel].fftPhPlus1S[j]);
if (psyInfo[channel].fftPhS[j]) FreeMemory(psyInfo[channel].fftPhS[j]);
if (psyInfo[channel].fftPhMin1S[j]) FreeMemory(psyInfo[channel].fftPhMin1S[j]);
}
}
}
/* Do psychoacoustical analysis */
void PsyCalculate(ChannelInfo *channelInfo, GlobalPsyInfo *gpsyInfo, PsyInfo *psyInfo,
int *cb_width_long, int num_cb_long, int *cb_width_short,
int num_cb_short, unsigned int numChannels)
{
unsigned int channel;
for (channel = 0; channel < numChannels; channel++) {
if (channelInfo[channel].present) {
if (channelInfo[channel].cpe &&
channelInfo[channel].ch_is_left) { /* CPE */
int leftChan = channel;
int rightChan = channelInfo[channel].paired_ch;
/* Calculate the unpredictability */
PsyUnpredictability(&psyInfo[leftChan]);
PsyUnpredictability(&psyInfo[rightChan]);
/* Calculate the threshold */
PsyThreshold(gpsyInfo, &psyInfo[leftChan], cb_width_long, num_cb_long,
cb_width_short, num_cb_short);
PsyThreshold(gpsyInfo, &psyInfo[rightChan], cb_width_long, num_cb_long,
cb_width_short, num_cb_short);
/* And for MS */
PsyThresholdMS(&channelInfo[leftChan], gpsyInfo, &psyInfo[leftChan],
&psyInfo[rightChan], cb_width_long, num_cb_long, cb_width_short,
num_cb_short);
} else if (!channelInfo[channel].cpe &&
channelInfo[channel].lfe) { /* LFE */
/* NOT FINISHED */
} else if (!channelInfo[channel].cpe) { /* SCE */
/* Calculate the unpredictability */
PsyUnpredictability(&psyInfo[channel]);
/* Calculate the threshold */
PsyThreshold(gpsyInfo, &psyInfo[channel], cb_width_long, num_cb_long,
cb_width_short, num_cb_short);
}
}
}
}
static void Hann(GlobalPsyInfo *gpsyInfo, double *inSamples, int size)
{
int i;
/* Applying Hann window */
if (size == BLOCK_LEN_LONG*2) {
for(i = 0; i < size; i++)
inSamples[i] *= gpsyInfo->hannWindow[i];
} else {
for(i = 0; i < size; i++)
inSamples[i] *= gpsyInfo->hannWindowS[i];
}
}
void PsyBufferUpdate(GlobalPsyInfo *gpsyInfo, PsyInfo *psyInfo, double *newSamples)
{
int i, j;
double a, b;
double *transBuff, *transBuffS, *tmp;
transBuff = (double*)AllocMemory(2*psyInfo->size*sizeof(double));
memcpy(transBuff, psyInfo->prevSamples, psyInfo->size*sizeof(double));
memcpy(transBuff + psyInfo->size, newSamples, psyInfo->size*sizeof(double));
/* In 2 frames this will be the frequencies where
the psychoacoustics are calculated for */
Hann(gpsyInfo, transBuff, 2*psyInfo->size);
rsfft(transBuff, 11);
/* shift all buffers 1 frame ahead */
tmp = psyInfo->fftMagMin2;
psyInfo->fftMagMin2 = psyInfo->fftMagMin1;
psyInfo->fftMagMin1 = psyInfo->fftMag;
psyInfo->fftMag = psyInfo->fftMagPlus1;
psyInfo->fftMagPlus1 = psyInfo->fftMagPlus2;
psyInfo->fftMagPlus2 = tmp;
tmp = psyInfo->fftPhMin2;
psyInfo->fftPhMin2 = psyInfo->fftPhMin1;
psyInfo->fftPhMin1 = psyInfo->fftPh;
psyInfo->fftPh = psyInfo->fftPhPlus1;
psyInfo->fftPhPlus1 = psyInfo->fftPhPlus2;
psyInfo->fftPhPlus2 = tmp;
/* Calculate magnitude and phase of new data */
for (i = 0; i < psyInfo->size; i++) {
a = transBuff[i];
b = transBuff[i + psyInfo->size];
psyInfo->fftMagPlus2[i] = sqrt(a*a + b*b);
if(a > 0.0){
if(b >= 0.0)
psyInfo->fftPhPlus2[i] = atan2(b, a);
else
psyInfo->fftPhPlus2[i] = atan2(b, a) + M_PI * 2.0;
} else if(a < 0.0) {
psyInfo->fftPhPlus2[i] = atan2(b, a) + M_PI;
} else {
if(b > 0.0)
psyInfo->fftPhPlus2[i] = M_PI * 0.5;
else if( b < 0.0 )
psyInfo->fftPhPlus2[i] = M_PI * 1.5;
else
psyInfo->fftPhPlus2[i] = 0.0;
}
}
transBuffS = (double*)AllocMemory(2*psyInfo->sizeS*sizeof(double));
memcpy(transBuff, psyInfo->prevSamples, psyInfo->size*sizeof(double));
memcpy(transBuff + psyInfo->size, newSamples, psyInfo->size*sizeof(double));
for (j = 0; j < 8; j++) {
memcpy(transBuffS, transBuff+(j*128)+(1024-128), 2*psyInfo->sizeS*sizeof(double));
/* In 2 frames this will be the frequencies where
the psychoacoustics are calculated for */
Hann(gpsyInfo, transBuffS, 2*psyInfo->sizeS);
rsfft(transBuffS, 8);
/* shift all buffers 1 frame ahead */
tmp = psyInfo->fftMagMin1S[j];
psyInfo->fftMagMin1S[j] = psyInfo->fftMagS[j];
psyInfo->fftMagS[j] = psyInfo->fftMagPlus1S[j];
psyInfo->fftMagPlus1S[j] = psyInfo->fftMagPlus2S[j];
psyInfo->fftMagPlus2S[j] = tmp;
tmp = psyInfo->fftPhMin1S[j];
psyInfo->fftPhMin1S[j] = psyInfo->fftPhS[j];
psyInfo->fftPhS[j] = psyInfo->fftPhPlus1S[j];
psyInfo->fftPhPlus1S[j] = psyInfo->fftPhPlus2S[j];
psyInfo->fftPhPlus2S[j] = tmp;
/* Calculate magnitude and phase of new data */
for (i = 0; i < psyInfo->sizeS; i++) {
a = transBuffS[i];
b = transBuffS[i + psyInfo->sizeS];
psyInfo->fftMagPlus2S[j][i] = sqrt(a*a + b*b);
if(a > 0.0){
if(b >= 0.0)
psyInfo->fftPhPlus2S[j][i] = atan2(b, a);
else
psyInfo->fftPhPlus2S[j][i] = atan2(b, a) + M_PI * 2.0;
} else if(a < 0.0) {
psyInfo->fftPhPlus2S[j][i] = atan2(b, a) + M_PI;
} else {
if(b > 0.0)
psyInfo->fftPhPlus2S[j][i] = M_PI * 0.5;
else if( b < 0.0 )
psyInfo->fftPhPlus2S[j][i] = M_PI * 1.5;
else
psyInfo->fftPhPlus2S[j][i] = 0.0;
}
}
}
memcpy(psyInfo->prevSamples, newSamples, psyInfo->size*sizeof(double));
if (transBuff) FreeMemory(transBuff);
if (transBuffS) FreeMemory(transBuffS);
}
static void PsyUnpredictability(PsyInfo *psyInfo)
{
int i, j;
double predMagMin, predMagPlus, predMag, mag;
double predPhMin, predPhPlus, predPh, ph;
for (i = 0; i < psyInfo->size; i++)
{
predMagMin = 2.0 * psyInfo->fftMagMin1[i] - psyInfo->fftMagMin2[i];
predMagPlus = 2.0 * psyInfo->fftMagPlus1[i] - psyInfo->fftMagPlus2[i];
predPhMin = 2.0 * psyInfo->fftPhMin1[i] - psyInfo->fftPhMin2[i];
predPhPlus = 2.0 * psyInfo->fftPhPlus1[i] - psyInfo->fftPhPlus2[i];
if ((predMagMin != 0.0) && (predMagPlus != 0.0)) {
if ((psyInfo->fftMag[i] - predMagMin) < (psyInfo->fftMag[i] - predMagPlus)) {
predMag = predMagMin;
predPh = predPhMin;
} else {
predMag = predMagPlus;
predPh = predPhPlus;
}
} else if (predMagMin == 0.0) {
predMag = predMagPlus;
predPh = predPhPlus;
} else { /* predMagPlus == 0.0 */
predMag = predMagMin;
predPh = predPhMin;
}
mag = psyInfo->fftMag[i];
ph = psyInfo->fftPh[i];
/* unpredictability */
psyInfo->cw[i] =
sqrt(mag*mag+predMag*predMag-2*mag*predMag*cos(ph+predPh))/(mag+fabs(predMag));
}
for (i = 0; i < psyInfo->sizeS; i++)
{
predMagMin = 2.0 * psyInfo->fftMagMin1S[7][i] - psyInfo->fftMagMin1S[6][i];
predMagPlus = 2.0 * psyInfo->fftMagS[1][i] - psyInfo->fftMagS[2][i];
predPhMin = 2.0 * psyInfo->fftPhMin1S[7][i] - psyInfo->fftPhMin1S[6][i];
predPhPlus = 2.0 * psyInfo->fftPhS[1][i] - psyInfo->fftPhS[2][i];
if ((predMagMin != 0.0) && (predMagPlus != 0.0)) {
if ((psyInfo->fftMagS[0][i] - predMagMin) < (psyInfo->fftMagS[0][i] - predMagPlus)) {
predMag = predMagMin;
predPh = predPhMin;
} else {
predMag = predMagPlus;
predPh = predPhPlus;
}
} else if (predMagMin == 0.0) {
predMag = predMagPlus;
predPh = predPhPlus;
} else { /* predMagPlus == 0.0 */
predMag = predMagMin;
predPh = predPhMin;
}
mag = psyInfo->fftMagS[0][i];
ph = psyInfo->fftPhS[0][i];
/* unpredictability */
psyInfo->cwS[0][i] =
sqrt(mag*mag+predMag*predMag-2*mag*predMag*cos(ph+predPh))/(mag+fabs(predMag));
}
for (i = 0; i < psyInfo->sizeS; i++)
{
predMagMin = 2.0 * psyInfo->fftMagS[0][i] - psyInfo->fftMagMin1S[7][i];
predMagPlus = 2.0 * psyInfo->fftMagS[2][i] - psyInfo->fftMagS[3][i];
predPhMin = 2.0 * psyInfo->fftPhS[0][i] - psyInfo->fftPhMin1S[7][i];
predPhPlus = 2.0 * psyInfo->fftPhS[2][i] - psyInfo->fftPhS[3][i];
if ((predMagMin != 0.0) && (predMagPlus != 0.0)) {
if ((psyInfo->fftMagS[1][i] - predMagMin) < (psyInfo->fftMagS[1][i] - predMagPlus)) {
predMag = predMagMin;
predPh = predPhMin;
} else {
predMag = predMagPlus;
predPh = predPhPlus;
}
} else if (predMagMin == 0.0) {
predMag = predMagPlus;
predPh = predPhPlus;
} else { /* predMagPlus == 0.0 */
predMag = predMagMin;
predPh = predPhMin;
}
mag = psyInfo->fftMagS[1][i];
ph = psyInfo->fftPhS[1][i];
/* unpredictability */
psyInfo->cwS[1][i] =
sqrt(mag*mag+predMag*predMag-2*mag*predMag*cos(ph+predPh))/(mag+fabs(predMag));
}
for (j = 2; j < 6; j++) {
for (i = 0; i < psyInfo->sizeS; i++)
{
predMagMin = 2.0 * psyInfo->fftMagS[j-1][i] - psyInfo->fftMagS[j-2][i];
predMagPlus = 2.0 * psyInfo->fftMagS[j+1][i] - psyInfo->fftMagS[j+2][i];
predPhMin = 2.0 * psyInfo->fftPhS[j-1][i] - psyInfo->fftPhS[j-2][i];
predPhPlus = 2.0 * psyInfo->fftPhS[j+1][i] - psyInfo->fftPhS[j+2][i];
if ((predMagMin != 0.0) && (predMagPlus != 0.0)) {
if ((psyInfo->fftMagS[j][i] - predMagMin) < (psyInfo->fftMagS[j][i] - predMagPlus)) {
predMag = predMagMin;
predPh = predPhMin;
} else {
predMag = predMagPlus;
predPh = predPhPlus;
}
} else if (predMagMin == 0.0) {
predMag = predMagPlus;
predPh = predPhPlus;
} else { /* predMagPlus == 0.0 */
predMag = predMagMin;
predPh = predPhMin;
}
mag = psyInfo->fftMagS[j][i];
ph = psyInfo->fftPhS[j][i];
/* unpredictability */
psyInfo->cwS[j][i] =
sqrt(mag*mag+predMag*predMag-2*mag*predMag*cos(ph+predPh))/(mag+fabs(predMag));
}
}
for (i = 0; i < psyInfo->sizeS; i++)
{
predMagMin = 2.0 * psyInfo->fftMagS[5][i] - psyInfo->fftMagS[4][i];
predMagPlus = 2.0 * psyInfo->fftMagS[7][i] - psyInfo->fftMagPlus1S[0][i];
predPhMin = 2.0 * psyInfo->fftPhS[5][i] - psyInfo->fftPhS[4][i];
predPhPlus = 2.0 * psyInfo->fftPhS[7][i] - psyInfo->fftPhPlus1S[0][i];
if ((predMagMin != 0.0) && (predMagPlus != 0.0)) {
if ((psyInfo->fftMagS[6][i] - predMagMin) < (psyInfo->fftMagS[6][i] - predMagPlus)) {
predMag = predMagMin;
predPh = predPhMin;
} else {
predMag = predMagPlus;
predPh = predPhPlus;
}
} else if (predMagMin == 0.0) {
predMag = predMagPlus;
predPh = predPhPlus;
} else { /* predMagPlus == 0.0 */
predMag = predMagMin;
predPh = predPhMin;
}
mag = psyInfo->fftMagS[6][i];
ph = psyInfo->fftPhS[6][i];
/* unpredictability */
psyInfo->cwS[6][i] =
sqrt(mag*mag+predMag*predMag-2*mag*predMag*cos(ph+predPh))/(mag+fabs(predMag));
}
for (i = 0; i < psyInfo->sizeS; i++)
{
predMagMin = 2.0 * psyInfo->fftMagS[6][i] - psyInfo->fftMagMin1S[5][i];
predMagPlus = 2.0 * psyInfo->fftMagPlus1S[0][i] - psyInfo->fftMagPlus1S[1][i];
predPhMin = 2.0 * psyInfo->fftPhS[6][i] - psyInfo->fftPhS[5][i];
predPhPlus = 2.0 * psyInfo->fftPhPlus1S[0][i] - psyInfo->fftPhPlus1S[1][i];
if ((predMagMin != 0.0) && (predMagPlus != 0.0)) {
if ((psyInfo->fftMagS[7][i] - predMagMin) < (psyInfo->fftMagS[7][i] - predMagPlus)) {
predMag = predMagMin;
predPh = predPhMin;
} else {
predMag = predMagPlus;
predPh = predPhPlus;
}
} else if (predMagMin == 0.0) {
predMag = predMagPlus;
predPh = predPhPlus;
} else { /* predMagPlus == 0.0 */
predMag = predMagMin;
predPh = predPhMin;
}
mag = psyInfo->fftMagS[7][i];
ph = psyInfo->fftPhS[7][i];
/* unpredictability */
psyInfo->cwS[7][i] =
sqrt(mag*mag+predMag*predMag-2*mag*predMag*cos(ph+predPh))/(mag+fabs(predMag));
}
}
static void PsyThreshold(GlobalPsyInfo *gpsyInfo, PsyInfo *psyInfo, int *cb_width_long,
int num_cb_long, int *cb_width_short, int num_cb_short)
{
int b, bb, w, low, high, j;
double tmp, ct, ecb, cb;
double tb, snr, bc, en, nb;
double e[MAX_SCFAC_BANDS];
double c[MAX_SCFAC_BANDS];
double tot, mx, estot[8];
double pe = 0.0;
/* Energy in each partition and weighted unpredictability */
high = 0;
for (b = 0; b < num_cb_long; b++)
{
low = high;
high += cb_width_long[b];
e[b] = 0.0;
c[b] = 0.0;
for (w = low; w < high; w++)
{
tmp = psyInfo->fftMag[w];
tmp *= tmp;
e[b] += tmp;
c[b] += tmp * psyInfo->cw[w];
}
}
/* Convolve the partitioned energy and unpredictability
with the spreading function */
for (b = 0; b < num_cb_long; b++)
{
ecb = 0.0;
ct = 0.0;
for (bb = 0; bb < num_cb_long; bb++)
{
ecb += e[bb] * gpsyInfo->spreading[bb][b];
ct += c[bb] * gpsyInfo->spreading[bb][b];
}
if (ecb != 0.0) cb = ct / ecb;
else cb = 0.0;
en = ecb * gpsyInfo->rnorm[b];
/* Get the tonality index */
tb = -0.299 - 0.43*log(cb);
tb = max(min(tb,1),0);
/* Calculate the required SNR in each partition */
snr = tb * 18.0 + (1-tb) * 6.0;
/* Power ratio */
bc = pow(10.0, 0.1*(-snr));
/* Actual energy threshold */
nb = en * bc;
nb = max(min(nb, psyInfo->lastNb[b]*2), gpsyInfo->ath[b]);
psyInfo->lastNb[b] = en * bc;
/* Perceptual entropy */
tmp = cb_width_long[b]
* log((nb + 0.0000000001)
/ (e[b] + 0.0000000001));
tmp = min(0,tmp);
pe -= tmp;
psyInfo->maskThr[b] = psyInfo->maskThrNext[b];
psyInfo->maskEn[b] = psyInfo->maskEnNext[b];
psyInfo->maskThrNext[b] = nb;
psyInfo->maskEnNext[b] = en;
}
/* Short windows */
for (j = 0; j < 8; j++)
{
/* Energy in each partition and weighted unpredictability */
high = 0;
for (b = 0; b < num_cb_short; b++)
{
low = high;
high += cb_width_short[b];
e[b] = 0.0;
c[b] = 0.0;
for (w = low; w < high; w++)
{
tmp = psyInfo->fftMagS[j][w];
tmp *= tmp;
e[b] += tmp;
c[b] += tmp * psyInfo->cwS[j][w];
}
}
estot[j] = 0.0;
/* Convolve the partitioned energy and unpredictability
with the spreading function */
for (b = 0; b < num_cb_short; b++)
{
ecb = 0.0;
ct = 0.0;
for (bb = 0; bb < num_cb_short; bb++)
{
ecb += e[bb] * gpsyInfo->spreadingS[bb][b];
ct += c[bb] * gpsyInfo->spreadingS[bb][b];
}
if (ecb != 0.0) cb = ct / ecb;
else cb = 0.0;
en = ecb * gpsyInfo->rnormS[b];
/* Get the tonality index */
tb = -0.299 - 0.43*log(cb);
tb = max(min(tb,1),0);
/* Calculate the required SNR in each partition */
snr = tb * 18.0 + (1-tb) * 6.0;
/* Power ratio */
bc = pow(10.0, 0.1*(-snr));
/* Actual energy threshold */
nb = en * bc;
nb = max(nb, gpsyInfo->athS[b]);
estot[j] += e[b];
psyInfo->maskThrS[j][b] = psyInfo->maskThrNextS[j][b];
psyInfo->maskEnS[j][b] = psyInfo->maskEnNextS[j][b];
psyInfo->maskThrNextS[j][b] = nb;
psyInfo->maskEnNextS[j][b] = en;
}
if (estot[j] != 0.0)
estot[j] /= num_cb_short;
}
tot = mx = estot[0];
for (j = 1; j < 8; j++) {
tot += estot[j];
mx = max(mx, estot[j]);
}
tot = max(tot, 1.e-12);
if (((mx/tot) > 0.25) && (pe > 1100.0) || ((mx/tot) > 0.5)) {
psyInfo->block_type = ONLY_SHORT_WINDOW;
psyInfo->threeInARow++;
} else if ((psyInfo->lastEnr > 0.35) && (psyInfo->lastPe > 1000.0)) {
psyInfo->block_type = ONLY_SHORT_WINDOW;
psyInfo->threeInARow++;
} else if (psyInfo->threeInARow >= 3) {
psyInfo->block_type = ONLY_SHORT_WINDOW;
psyInfo->threeInARow = 0;
} else
psyInfo->block_type = ONLY_LONG_WINDOW;
psyInfo->lastEnr = mx/tot;
psyInfo->lastPe = pe;
}
static void PsyThresholdMS(ChannelInfo *channelInfoL, GlobalPsyInfo *gpsyInfo,
PsyInfo *psyInfoL, PsyInfo *psyInfoR,
int *cb_width_long, int num_cb_long, int *cb_width_short,
int num_cb_short)
{
int b, bb, w, low, high, j;
double tmp, ct, ecb, cb;
double tb, snr, bc, enM, enS, nbM, nbS;
double eM[MAX_SCFAC_BANDS];
double eS[MAX_SCFAC_BANDS];
double cM[MAX_SCFAC_BANDS];
double cS[MAX_SCFAC_BANDS];
double x1, x2, db, mld;
#ifdef _DEBUG
int ms_used = 0;
int ms_usedS = 0;
#endif
/* Energy in each partition and weighted unpredictability */
high = 0;
for (b = 0; b < num_cb_long; b++)
{
low = high;
high += cb_width_long[b];
eM[b] = 0.0;
cM[b] = 0.0;
eS[b] = 0.0;
cS[b] = 0.0;
for (w = low; w < high; w++)
{
tmp = (psyInfoL->fftMag[w] + psyInfoR->fftMag[w]) * 0.5;
tmp *= tmp;
eM[b] += tmp;
cM[b] += tmp * min(psyInfoL->cw[w], psyInfoR->cw[w]);
tmp = (psyInfoL->fftMag[w] - psyInfoR->fftMag[w]) * 0.5;
tmp *= tmp;
eS[b] += tmp;
cS[b] += tmp * min(psyInfoL->cw[w], psyInfoR->cw[w]);
}
}
/* Convolve the partitioned energy and unpredictability
with the spreading function */
for (b = 0; b < num_cb_long; b++)
{
/* Mid channel */
ecb = 0.0;
ct = 0.0;
for (bb = 0; bb < num_cb_long; bb++)
{
ecb += eM[bb] * gpsyInfo->spreading[bb][b];
ct += cM[bb] * gpsyInfo->spreading[bb][b];
}
if (ecb != 0.0) cb = ct / ecb;
else cb = 0.0;
enM = ecb * gpsyInfo->rnorm[b];
/* Get the tonality index */
tb = -0.299 - 0.43*log(cb);
tb = max(min(tb,1),0);
/* Calculate the required SNR in each partition */
snr = tb * 18.0 + (1-tb) * 6.0;
/* Power ratio */
bc = pow(10.0, 0.1*(-snr));
/* Actual energy threshold */
nbM = enM * bc;
nbM = max(min(nbM, psyInfoL->lastNbMS[b]*2), gpsyInfo->ath[b]);
psyInfoL->lastNbMS[b] = enM * bc;
/* Side channel */
ecb = 0.0;
ct = 0.0;
for (bb = 0; bb < num_cb_long; bb++)
{
ecb += eS[bb] * gpsyInfo->spreading[bb][b];
ct += cS[bb] * gpsyInfo->spreading[bb][b];
}
if (ecb != 0.0) cb = ct / ecb;
else cb = 0.0;
enS = ecb * gpsyInfo->rnorm[b];
/* Get the tonality index */
tb = -0.299 - 0.43*log(cb);
tb = max(min(tb,1),0);
/* Calculate the required SNR in each partition */
snr = tb * 18.0 + (1-tb) * 6.0;
/* Power ratio */
bc = pow(10.0, 0.1*(-snr));
/* Actual energy threshold */
nbS = enS * bc;
nbS = max(min(nbS, psyInfoR->lastNbMS[b]*2), gpsyInfo->ath[b]);
psyInfoR->lastNbMS[b] = enS * bc;
psyInfoL->maskThrMS[b] = psyInfoL->maskThrNextMS[b];
psyInfoR->maskThrMS[b] = psyInfoR->maskThrNextMS[b];
psyInfoL->maskEnMS[b] = psyInfoL->maskEnNextMS[b];
psyInfoR->maskEnMS[b] = psyInfoR->maskEnNextMS[b];
psyInfoL->maskThrNextMS[b] = nbM;
psyInfoR->maskThrNextMS[b] = nbS;
psyInfoL->maskEnNextMS[b] = enM;
psyInfoR->maskEnNextMS[b] = enS;
if (psyInfoL->maskThr[b] <= 1.58*psyInfoR->maskThr[b]
&& psyInfoR->maskThr[b] <= 1.58*psyInfoL->maskThr[b]) {
mld = gpsyInfo->mld[b]*enM;
psyInfoL->maskThrMS[b] = max(psyInfoL->maskThrMS[b],
min(psyInfoR->maskThrMS[b],mld));
mld = gpsyInfo->mld[b]*enS;
psyInfoR->maskThrMS[b] = max(psyInfoR->maskThrMS[b],
min(psyInfoL->maskThrMS[b],mld));
}
x1 = min(psyInfoL->maskThr[b], psyInfoR->maskThr[b]);
x2 = max(psyInfoL->maskThr[b], psyInfoR->maskThr[b]);
/* thresholds difference in db */
if (x2 >= 1000*x1) db=3;
else db = log10(x2/x1);
if (db < 0.25) {
#ifdef _DEBUG
ms_used++;
#endif
channelInfoL->msInfo.ms_used[b] = 1;
} else {
channelInfoL->msInfo.ms_used[b] = 0;
}
}
#ifdef _DEBUG
printf("%d\t", ms_used);
#endif
/* Short windows */
for (j = 0; j < 8; j++)
{
/* Energy in each partition and weighted unpredictability */
high = 0;
for (b = 0; b < num_cb_short; b++)
{
low = high;
high += cb_width_short[b];
eM[b] = 0.0;
eS[b] = 0.0;
cM[b] = 0.0;
cS[b] = 0.0;
for (w = low; w < high; w++)
{
tmp = (psyInfoL->fftMagS[j][w] + psyInfoR->fftMagS[j][w]) * 0.5;
tmp *= tmp;
eM[b] += tmp;
cM[b] += tmp * min(psyInfoL->cwS[j][w], psyInfoR->cwS[j][w]);
tmp = (psyInfoL->fftMagS[j][w] - psyInfoR->fftMagS[j][w]) * 0.5;
tmp *= tmp;
eS[b] += tmp;
cS[b] += tmp * min(psyInfoL->cwS[j][w], psyInfoR->cwS[j][w]);
}
}
/* Convolve the partitioned energy and unpredictability
with the spreading function */
for (b = 0; b < num_cb_short; b++)
{
/* Mid channel */
ecb = 0.0;
ct = 0.0;
for (bb = 0; bb < num_cb_short; bb++)
{
ecb += eM[bb] * gpsyInfo->spreadingS[bb][b];
ct += cM[bb] * gpsyInfo->spreadingS[bb][b];
}
if (ecb != 0.0) cb = ct / ecb;
else cb = 0.0;
enM = ecb * gpsyInfo->rnormS[b];
/* Get the tonality index */
tb = -0.299 - 0.43*log(cb);
tb = max(min(tb,1),0);
/* Calculate the required SNR in each partition */
snr = tb * 18.0 + (1-tb) * 6.0;
/* Power ratio */
bc = pow(10.0, 0.1*(-snr));
/* Actual energy threshold */
nbM = enM * bc;
nbM = max(nbM, gpsyInfo->athS[b]);
/* Side channel */
ecb = 0.0;
ct = 0.0;
for (bb = 0; bb < num_cb_short; bb++)
{
ecb += eS[bb] * gpsyInfo->spreadingS[bb][b];
ct += cS[bb] * gpsyInfo->spreadingS[bb][b];
}
if (ecb != 0.0) cb = ct / ecb;
else cb = 0.0;
enS = ecb * gpsyInfo->rnormS[b];
/* Get the tonality index */
tb = -0.299 - 0.43*log(cb);
tb = max(min(tb,1),0);
/* Calculate the required SNR in each partition */
snr = tb * 18.0 + (1-tb) * 6.0;
/* Power ratio */
bc = pow(10.0, 0.1*(-snr));
/* Actual energy threshold */
nbS = enS * bc;
nbS = max(nbS, gpsyInfo->athS[b]);
psyInfoL->maskThrSMS[j][b] = psyInfoL->maskThrNextSMS[j][b];
psyInfoR->maskThrSMS[j][b] = psyInfoR->maskThrNextSMS[j][b];
psyInfoL->maskEnSMS[j][b] = psyInfoL->maskEnNextSMS[j][b];
psyInfoR->maskEnSMS[j][b] = psyInfoR->maskEnNextSMS[j][b];
psyInfoL->maskThrNextSMS[j][b] = nbM;
psyInfoR->maskThrNextSMS[j][b] = nbS;
psyInfoL->maskEnNextSMS[j][b] = enM;
psyInfoR->maskEnNextSMS[j][b] = enS;
if (psyInfoL->maskThrS[j][b] <= 1.58*psyInfoR->maskThrS[j][b]
&& psyInfoR->maskThrS[j][b] <= 1.58*psyInfoL->maskThrS[j][b]) {
mld = gpsyInfo->mldS[b]*enM;
psyInfoL->maskThrSMS[j][b] = max(psyInfoL->maskThrSMS[j][b],
min(psyInfoR->maskThrSMS[j][b],mld));
mld = gpsyInfo->mldS[b]*enS;
psyInfoR->maskThrSMS[j][b] = max(psyInfoR->maskThrSMS[j][b],
min(psyInfoL->maskThrSMS[j][b],mld));
}
x1 = min(psyInfoL->maskThrS[j][b], psyInfoR->maskThrS[j][b]);
x2 = max(psyInfoL->maskThrS[j][b], psyInfoR->maskThrS[j][b]);
/* thresholds difference in db */
if (x2 >= 1000*x1) db = 3;
else db = log10(x2/x1);
if (db < 0.25) {
#ifdef _DEBUG
ms_usedS++;
#endif
channelInfoL->msInfo.ms_usedS[j][b] = 1;
} else {
channelInfoL->msInfo.ms_usedS[j][b] = 0;
}
}
}
#ifdef _DEBUG
printf("%d\t", ms_usedS);
#endif
}
void BlockSwitch(CoderInfo *coderInfo, PsyInfo *psyInfo, unsigned int numChannels)
{
unsigned int channel;
int desire = ONLY_LONG_WINDOW;
/* Use the same block type for all channels
If there is 1 channel that wants a short block,
use a short block on all channels.
*/
for (channel = 0; channel < numChannels; channel++)
{
if (psyInfo[channel].block_type == ONLY_SHORT_WINDOW)
desire = ONLY_SHORT_WINDOW;
}
for (channel = 0; channel < numChannels; channel++)
{
if ((coderInfo[channel].block_type == ONLY_SHORT_WINDOW) ||
(coderInfo[channel].block_type == LONG_SHORT_WINDOW) ) {
if ((coderInfo[channel].desired_block_type==ONLY_LONG_WINDOW) &&
(desire == ONLY_LONG_WINDOW) ) {
coderInfo[channel].block_type = SHORT_LONG_WINDOW;
} else {
coderInfo[channel].block_type = ONLY_SHORT_WINDOW;
}
} else if (desire == ONLY_SHORT_WINDOW) {
coderInfo[channel].block_type = LONG_SHORT_WINDOW;
} else {
coderInfo[channel].block_type = ONLY_LONG_WINDOW;
}
coderInfo[channel].desired_block_type = desire;
}
}
static double freq2bark(double freq)
{
double bark;
if(freq > 200.0)
bark = 26.81 / (1 + (1960 / freq)) - 0.53;
else
bark = freq / 102.9;
return (bark);
}
static double ATHformula(double f)
{
double ath;
f /= 1000; // convert to khz
f = max(0.01, f);
f = min(18.0,f);
/* from Painter & Spanias, 1997 */
/* minimum: (i=77) 3.3kHz = -5db */
ath = 3.640 * pow(f,-0.8)
- 6.500 * exp(-0.6*pow(f-3.3,2.0))
+ 0.001 * pow(f,4.0);
return ath;
}