ref: d04af1ccc8ae96d05a18d4742206712d24a02d38
dir: /libfaac/tns.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: tns.c,v 1.6 2001/04/19 13:20:34 menno Exp $
*/
#include <math.h>
#include "frame.h"
#include "coder.h"
#include "bitstream.h"
#include "tns.h"
#include "util.h"
/***********************************************/
/* TNS Profile/Frequency Dependent Parameters */
/***********************************************/
static unsigned long tnsSupportedSamplingRates[13] =
{ 96000,88200,64000,48000,44100,32000,24000,22050,16000,12000,11025,8000,0 };
/* Limit bands to > 2.0 kHz */
static unsigned short tnsMinBandNumberLong[12] =
{ 11, 12, 15, 16, 17, 20, 25, 26, 24, 28, 30, 31 };
static unsigned short tnsMinBandNumberShort[12] =
{ 2, 2, 2, 3, 3, 4, 6, 6, 8, 10, 10, 12 };
/**************************************/
/* Main/Low Profile TNS Parameters */
/**************************************/
static unsigned short tnsMaxBandsLongMainLow[12] =
{ 31, 31, 34, 40, 42, 51, 46, 46, 42, 42, 42, 39 };
static unsigned short tnsMaxBandsShortMainLow[12] =
{ 9, 9, 10, 14, 14, 14, 14, 14, 14, 14, 14, 14 };
static unsigned short tnsMaxOrderLongMain = 20;
static unsigned short tnsMaxOrderLongLow = 12;
static unsigned short tnsMaxOrderShortMainLow = 7;
/*****************************************************/
/* InitTns: */
/*****************************************************/
void TnsInit(faacEncHandle hEncoder)
{
unsigned int channel;
int fsIndex = hEncoder->sampleRateIdx;
int profile = hEncoder->config.aacObjectType;
for (channel = 0; channel < hEncoder->numChannels; channel++) {
TnsInfo *tnsInfo = &hEncoder->coderInfo[channel].tnsInfo;
switch( profile ) {
case MAIN:
case LTP:
tnsInfo->tnsMaxBandsLong = tnsMaxBandsLongMainLow[fsIndex];
tnsInfo->tnsMaxBandsShort = tnsMaxBandsShortMainLow[fsIndex];
if (hEncoder->config.mpegVersion == 1) { /* MPEG2 */
tnsInfo->tnsMaxOrderLong = tnsMaxOrderLongMain;
} else { /* MPEG4 */
if (fsIndex <= 5) /* fs > 32000Hz */
tnsInfo->tnsMaxOrderLong = 12;
else
tnsInfo->tnsMaxOrderLong = 20;
}
tnsInfo->tnsMaxOrderShort = tnsMaxOrderShortMainLow;
break;
case LOW :
tnsInfo->tnsMaxBandsLong = tnsMaxBandsLongMainLow[fsIndex];
tnsInfo->tnsMaxBandsShort = tnsMaxBandsShortMainLow[fsIndex];
if (hEncoder->config.mpegVersion == 1) { /* MPEG2 */
tnsInfo->tnsMaxOrderLong = tnsMaxOrderLongLow;
} else { /* MPEG4 */
if (fsIndex <= 5) /* fs > 32000Hz */
tnsInfo->tnsMaxOrderLong = 12;
else
tnsInfo->tnsMaxOrderLong = 20;
}
tnsInfo->tnsMaxOrderShort = tnsMaxOrderShortMainLow;
break;
}
tnsInfo->tnsMinBandNumberLong = tnsMinBandNumberLong[fsIndex];
tnsInfo->tnsMinBandNumberShort = tnsMinBandNumberShort[fsIndex];
}
}
/*****************************************************/
/* TnsEncode: */
/*****************************************************/
void TnsEncode(TnsInfo* tnsInfo, /* TNS info */
int numberOfBands, /* Number of bands per window */
int maxSfb, /* max_sfb */
enum WINDOW_TYPE blockType, /* block type */
int* sfbOffsetTable, /* Scalefactor band offset table */
double* spec) /* Spectral data array */
{
int numberOfWindows,windowSize;
int startBand,stopBand,order; /* Bands over which to apply TNS */
int lengthInBands; /* Length to filter, in bands */
int w;
int startIndex,length;
double gain;
switch( blockType ) {
case ONLY_SHORT_WINDOW :
/* TNS not used for short blocks currently */
tnsInfo->tnsDataPresent = 0;
return;
numberOfWindows = MAX_SHORT_WINDOWS;
windowSize = BLOCK_LEN_SHORT;
startBand = tnsInfo->tnsMinBandNumberShort;
stopBand = numberOfBands;
lengthInBands = stopBand-startBand;
order = tnsInfo->tnsMaxOrderShort;
startBand = min(startBand,tnsInfo->tnsMaxBandsShort);
stopBand = min(stopBand,tnsInfo->tnsMaxBandsShort);
break;
default:
numberOfWindows = 1;
windowSize = BLOCK_LEN_SHORT;
startBand = tnsInfo->tnsMinBandNumberLong;
stopBand = numberOfBands;
lengthInBands = stopBand - startBand;
order = tnsInfo->tnsMaxOrderLong;
startBand = min(startBand,tnsInfo->tnsMaxBandsLong);
stopBand = min(stopBand,tnsInfo->tnsMaxBandsLong);
break;
}
/* Make sure that start and stop bands < maxSfb */
/* Make sure that start and stop bands >= 0 */
startBand = min(startBand,maxSfb);
stopBand = min(stopBand,maxSfb);
startBand = max(startBand,0);
stopBand = max(stopBand,0);
tnsInfo->tnsDataPresent = 0; /* default TNS not used */
/* Perform analysis and filtering for each window */
for (w=0;w<numberOfWindows;w++) {
TnsWindowData* windowData = &tnsInfo->windowData[w];
TnsFilterData* tnsFilter = windowData->tnsFilter;
double* k = tnsFilter->kCoeffs; /* reflection coeffs */
double* a = tnsFilter->aCoeffs; /* prediction coeffs */
windowData->numFilters=0;
windowData->coefResolution = DEF_TNS_COEFF_RES;
startIndex = w * windowSize + sfbOffsetTable[startBand];
length = sfbOffsetTable[stopBand] - sfbOffsetTable[startBand];
gain = LevinsonDurbin(order,length,&spec[startIndex],k);
if (gain>DEF_TNS_GAIN_THRESH) { /* Use TNS */
int truncatedOrder;
windowData->numFilters++;
tnsInfo->tnsDataPresent=1;
tnsFilter->direction = 0;
tnsFilter->coefCompress = 0;
tnsFilter->length = lengthInBands;
QuantizeReflectionCoeffs(order,DEF_TNS_COEFF_RES,k,tnsFilter->index);
truncatedOrder = TruncateCoeffs(order,DEF_TNS_COEFF_THRESH,k);
tnsFilter->order = truncatedOrder;
StepUp(truncatedOrder,k,a); /* Compute predictor coefficients */
TnsInvFilter(length,&spec[startIndex],tnsFilter); /* Filter */
}
}
}
/*****************************************************/
/* TnsEncodeFilterOnly: */
/* This is a stripped-down version of TnsEncode() */
/* which performs TNS analysis filtering only */
/*****************************************************/
void TnsEncodeFilterOnly(TnsInfo* tnsInfo, /* TNS info */
int numberOfBands, /* Number of bands per window */
int maxSfb, /* max_sfb */
enum WINDOW_TYPE blockType, /* block type */
int* sfbOffsetTable, /* Scalefactor band offset table */
double* spec) /* Spectral data array */
{
int numberOfWindows,windowSize;
int startBand,stopBand; /* Bands over which to apply TNS */
int w;
int startIndex,length;
switch( blockType ) {
case ONLY_SHORT_WINDOW :
numberOfWindows = MAX_SHORT_WINDOWS;
windowSize = BLOCK_LEN_SHORT;
startBand = tnsInfo->tnsMinBandNumberShort;
stopBand = numberOfBands;
startBand = min(startBand,tnsInfo->tnsMaxBandsShort);
stopBand = min(stopBand,tnsInfo->tnsMaxBandsShort);
break;
default:
numberOfWindows = 1;
windowSize = BLOCK_LEN_LONG;
startBand = tnsInfo->tnsMinBandNumberLong;
stopBand = numberOfBands;
startBand = min(startBand,tnsInfo->tnsMaxBandsLong);
stopBand = min(stopBand,tnsInfo->tnsMaxBandsLong);
break;
}
/* Make sure that start and stop bands < maxSfb */
/* Make sure that start and stop bands >= 0 */
startBand = min(startBand,maxSfb);
stopBand = min(stopBand,maxSfb);
startBand = max(startBand,0);
stopBand = max(stopBand,0);
/* Perform filtering for each window */
for(w=0;w<numberOfWindows;w++)
{
TnsWindowData* windowData = &tnsInfo->windowData[w];
TnsFilterData* tnsFilter = windowData->tnsFilter;
startIndex = w * windowSize + sfbOffsetTable[startBand];
length = sfbOffsetTable[stopBand] - sfbOffsetTable[startBand];
if (tnsInfo->tnsDataPresent && windowData->numFilters) { /* Use TNS */
TnsInvFilter(length,&spec[startIndex],tnsFilter);
}
}
}
/*****************************************************/
/* TnsDecodeFilterOnly: */
/* This is a stripped-down version of TnsEncode() */
/* which performs TNS synthesis filtering only */
/*****************************************************/
void TnsDecodeFilterOnly(TnsInfo* tnsInfo, /* TNS info */
int numberOfBands, /* Number of bands per window */
int maxSfb, /* max_sfb */
enum WINDOW_TYPE blockType, /* block type */
int* sfbOffsetTable, /* Scalefactor band offset table */
double* spec) /* Spectral data array */
{
int numberOfWindows,windowSize;
int startBand,stopBand; /* Bands over which to apply TNS */
int w;
int startIndex,length;
switch( blockType ) {
case ONLY_SHORT_WINDOW :
numberOfWindows = MAX_SHORT_WINDOWS;
windowSize = BLOCK_LEN_SHORT;
startBand = tnsInfo->tnsMinBandNumberShort;
stopBand = numberOfBands;
startBand = min(startBand,tnsInfo->tnsMaxBandsShort);
stopBand = min(stopBand,tnsInfo->tnsMaxBandsShort);
break;
default:
numberOfWindows = 1;
windowSize = BLOCK_LEN_LONG;
startBand = tnsInfo->tnsMinBandNumberLong;
stopBand = numberOfBands;
startBand = min(startBand,tnsInfo->tnsMaxBandsLong);
stopBand = min(stopBand,tnsInfo->tnsMaxBandsLong);
break;
}
/* Make sure that start and stop bands < maxSfb */
/* Make sure that start and stop bands >= 0 */
startBand = min(startBand,maxSfb);
stopBand = min(stopBand,maxSfb);
startBand = max(startBand,0);
stopBand = max(stopBand,0);
/* Perform filtering for each window */
for(w=0;w<numberOfWindows;w++)
{
TnsWindowData* windowData = &tnsInfo->windowData[w];
TnsFilterData* tnsFilter = windowData->tnsFilter;
startIndex = w * windowSize + sfbOffsetTable[startBand];
length = sfbOffsetTable[stopBand] - sfbOffsetTable[startBand];
if (tnsInfo->tnsDataPresent && windowData->numFilters) { /* Use TNS */
TnsFilter(length,&spec[startIndex],tnsFilter);
}
}
}
/*****************************************************/
/* TnsFilter: */
/* Filter the given spec with specified length */
/* using the coefficients specified in filter. */
/* Not that the order and direction are specified */
/* withing the TNS_FILTER_DATA structure. */
/*****************************************************/
static void TnsFilter(int length,double* spec,TnsFilterData* filter)
{
int i,j,k=0;
int order=filter->order;
double* a=filter->aCoeffs;
/* Determine loop parameters for given direction */
if (filter->direction) {
/* Startup, initial state is zero */
for (i=length-2;i>(length-1-order);i--) {
k++;
for (j=1;j<=k;j++) {
spec[i]-=spec[i+j]*a[j];
}
}
/* Now filter completely inplace */
for (i=length-1-order;i>=0;i--) {
for (j=1;j<=order;j++) {
spec[i]-=spec[i+j]*a[j];
}
}
} else {
/* Startup, initial state is zero */
for (i=1;i<order;i++) {
for (j=1;j<=i;j++) {
spec[i]-=spec[i-j]*a[j];
}
}
/* Now filter completely inplace */
for (i=order;i<length;i++) {
for (j=1;j<=order;j++) {
spec[i]-=spec[i-j]*a[j];
}
}
}
}
/********************************************************/
/* TnsInvFilter: */
/* Inverse filter the given spec with specified */
/* length using the coefficients specified in filter. */
/* Not that the order and direction are specified */
/* withing the TNS_FILTER_DATA structure. */
/********************************************************/
static void TnsInvFilter(int length,double* spec,TnsFilterData* filter)
{
int i,j,k=0;
int order=filter->order;
double* a=filter->aCoeffs;
double* temp;
temp = (double *)AllocMemory(length * sizeof (double));
/* Determine loop parameters for given direction */
if (filter->direction) {
/* Startup, initial state is zero */
temp[length-1]=spec[length-1];
for (i=length-2;i>(length-1-order);i--) {
temp[i]=spec[i];
k++;
for (j=1;j<=k;j++) {
spec[i]+=temp[i+j]*a[j];
}
}
/* Now filter the rest */
for (i=length-1-order;i>=0;i--) {
temp[i]=spec[i];
for (j=1;j<=order;j++) {
spec[i]+=temp[i+j]*a[j];
}
}
} else {
/* Startup, initial state is zero */
temp[0]=spec[0];
for (i=1;i<order;i++) {
temp[i]=spec[i];
for (j=1;j<=i;j++) {
spec[i]+=temp[i-j]*a[j];
}
}
/* Now filter the rest */
for (i=order;i<length;i++) {
temp[i]=spec[i];
for (j=1;j<=order;j++) {
spec[i]+=temp[i-j]*a[j];
}
}
}
if (temp) FreeMemory(temp);
}
/*****************************************************/
/* TruncateCoeffs: */
/* Truncate the given reflection coeffs by zeroing */
/* coefficients in the tail with absolute value */
/* less than the specified threshold. Return the */
/* truncated filter order. */
/*****************************************************/
static int TruncateCoeffs(int fOrder,double threshold,double* kArray)
{
int i;
for (i = fOrder; i >= 0; i--) {
kArray[i] = (fabs(kArray[i])>threshold) ? kArray[i] : 0.0;
if (kArray[i]!=0.0) return i;
}
return 0;
}
/*****************************************************/
/* QuantizeReflectionCoeffs: */
/* Quantize the given array of reflection coeffs */
/* to the specified resolution in bits. */
/*****************************************************/
static void QuantizeReflectionCoeffs(int fOrder,
int coeffRes,
double* kArray,
int* indexArray)
{
double iqfac,iqfac_m;
int i;
iqfac = ((1<<(coeffRes-1))-0.5)/(M_PI/2);
iqfac_m = ((1<<(coeffRes-1))+0.5)/(M_PI/2);
/* Quantize and inverse quantize */
for (i=1;i<=fOrder;i++) {
indexArray[i] = (int)(0.5+(asin(kArray[i])*((kArray[i]>=0)?iqfac:iqfac_m)));
kArray[i] = sin((double)indexArray[i]/((indexArray[i]>=0)?iqfac:iqfac_m));
}
}
/*****************************************************/
/* Autocorrelation, */
/* Compute the autocorrelation function */
/* estimate for the given data. */
/*****************************************************/
static void Autocorrelation(int maxOrder, /* Maximum autocorr order */
int dataSize, /* Size of the data array */
double* data, /* Data array */
double* rArray) /* Autocorrelation array */
{
int order,index;
for (order=0;order<=maxOrder;order++) {
rArray[order]=0.0;
for (index=0;index<dataSize;index++) {
rArray[order]+=data[index]*data[index+order];
}
dataSize--;
}
}
/*****************************************************/
/* LevinsonDurbin: */
/* Compute the reflection coefficients for the */
/* given data using LevinsonDurbin recursion. */
/* Return the prediction gain. */
/*****************************************************/
static double LevinsonDurbin(int fOrder, /* Filter order */
int dataSize, /* Size of the data array */
double* data, /* Data array */
double* kArray) /* Reflection coeff array */
{
int order,i;
double signal;
double error, kTemp; /* Prediction error */
double aArray1[TNS_MAX_ORDER+1]; /* Predictor coeff array */
double aArray2[TNS_MAX_ORDER+1]; /* Predictor coeff array 2 */
double rArray[TNS_MAX_ORDER+1]; /* Autocorrelation coeffs */
double* aPtr = aArray1; /* Ptr to aArray1 */
double* aLastPtr = aArray2; /* Ptr to aArray2 */
double* aTemp;
/* Compute autocorrelation coefficients */
Autocorrelation(fOrder,dataSize,data,rArray);
signal=rArray[0]; /* signal energy */
/* Set up pointers to current and last iteration */
/* predictor coefficients. */
aPtr = aArray1;
aLastPtr = aArray2;
/* If there is no signal energy, return */
if (!signal) {
kArray[0]=1.0;
for (order=1;order<=fOrder;order++) {
kArray[order]=0.0;
}
return 0;
} else {
/* Set up first iteration */
kArray[0]=1.0;
aPtr[0]=1.0; /* Ptr to predictor coeffs, current iteration*/
aLastPtr[0]=1.0; /* Ptr to predictor coeffs, last iteration */
error=rArray[0];
/* Now perform recursion */
for (order=1;order<=fOrder;order++) {
kTemp = aLastPtr[0]*rArray[order-0];
for (i=1;i<order;i++) {
kTemp += aLastPtr[i]*rArray[order-i];
}
kTemp = -kTemp/error;
kArray[order]=kTemp;
aPtr[order]=kTemp;
for (i=1;i<order;i++) {
aPtr[i] = aLastPtr[i] + kTemp*aLastPtr[order-i];
}
error = error * (1 - kTemp*kTemp);
/* Now make current iteration the last one */
aTemp=aLastPtr;
aLastPtr=aPtr; /* Current becomes last */
aPtr=aTemp; /* Last becomes current */
}
return signal/error; /* return the gain */
}
}
/*****************************************************/
/* StepUp: */
/* Convert reflection coefficients into */
/* predictor coefficients. */
/*****************************************************/
static void StepUp(int fOrder,double* kArray,double* aArray)
{
double aTemp[TNS_MAX_ORDER+2];
int i,order;
aArray[0]=1.0;
aTemp[0]=1.0;
for (order=1;order<=fOrder;order++) {
aArray[order]=0.0;
for (i=1;i<=order;i++) {
aTemp[i] = aArray[i] + kArray[order]*aArray[order-i];
}
for (i=1;i<=order;i++) {
aArray[i]=aTemp[i];
}
}
}