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sfklLPC.cpp
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sfklLPC.cpp
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// sfArkLib LPC
// copyright 1998-2000, Andy Inman
// Contact via: http://netgenius.co.uk or http://melodymachine.com
// This file is part of sfArkLib.
//
// sfArkLib 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 3 of the License, or
// (at your option) any later version.
//
// sfArkLib 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 sfArkLib. If not, see <http://www.gnu.org/licenses/>.
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include "wcc.h"
#include "zlib.h"
void LPCinit();
#define REFINT 1 // Integers for Reflection Coefficients (faster)
#define LPCWIN 4096
#define PMAX 128 // Max allowed nc
#define ZWINMIN 128 // 128 or 256 best. Smaller - slightly slower
#define ZWINMAX ZWINMIN
#if (LPCWIN / ZWINMIN) > 32 // Check use of 32bit *Flags
#error Invalid LPCWIN / ZWINMIN
#endif
// The following parameters determine the history sized used for LPC analysis (little impact on speed)
// The history is the amount of prev
#define HISTSIZE (4*128/ZWINMIN) // Multiple of number of ZWINs to use as history size (seems best value)
typedef LAWORD LPC_WORD; // LPC_WORD must have (slightly) greater range than AWORD
// There are compatibility issues in floating point calculations between Intel and Mac versions. Not sure if this
// is a compiler issue or a processor issue -- in short on Windows it seems that calculations performed on float
// datatype get done in double precision. So, we need to force the correct precision when used on Mac.
// Better longterm solution is to force single precision for all calculations (for the compressor also) but
// that would require a version update.
#if 0 // Use double for datatypes, convert to single before storage (doesn't work!)
typedef double LPC_FLOAT;
#else // Use single for datatypes, convert to double for calculations (works)
typedef float LPC_FLOAT;
#endif
typedef double XPN; // eXtra PrecisioN during calculations
typedef float LPN; // Lower PrecisioN to store results of calculations
#define ISCALE_BITS 14 // Fixed scale seems to work fine in practice
#define ISCALE (1 << ISCALE_BITS)
#if REFINT == 1
typedef long LPC_PRAM;
#else
typedef LPC_FLOAT LPC_PRAM;
#endif
typedef LPC_FLOAT LPC_CORR;
typedef LPC_FLOAT LPC_CORR2; // Holds LPC_CORR*LPC_CORR
// ======================================================================
LPC_CORR schur( // returns the minimum mean square error
LPC_CORR const * ac, // in: [0...p] autocorrelation values
int nc, // in: number of ref. coeff
LPC_PRAM * ref) // out: [0...p-1] reflection coefficients
{
int i, m;
LPC_CORR2 error, r;
LPC_CORR2 Gen0[PMAX], Gen1[PMAX];
if (ac[0] == 0)
{
for (i = 0; i < nc; i++) ref[i] = 0;
return 0;
}
// Initialize the rows of the generator matrix G to ac[1...p].
error = ac[0];
for (i = 0; i < nc; i++)
Gen0[i] = Gen1[i] = ac[i + 1];
// static int blk = 0;
for (i = 0;;)
{
// Calculate this iteration's reflection coefficient and error.
r = - (LPN) ((XPN)Gen1[0] / (XPN)error);
error = (LPN) ( (XPN)error + ((XPN)Gen1[0] * (XPN)r) );
#if REFINT == 1
ref[i] = (LPC_PRAM) ( (LPN)((XPN)r * ISCALE)) ; // Scale-up to avoid loss of precision
#else
ref[i] = r;
#endif
if (++i >= nc) break;
// Update the generator matrix.
for (m = 0; m < nc - i; m++)
{
// Gen1[m] = (XPN) Gen1[m + 1] + ((XPN) r * (XPN) Gen0[m]);
// Gen0[m] = (XPN) Gen0[m] + ((XPN) r * (XPN) Gen1[m + 1]);
Gen1[m] = (LPN) ( (XPN) Gen1[m + 1] + ((XPN) r * (XPN) Gen0[m]) );
Gen0[m] = (LPN) ( (XPN) Gen0[m] + ((XPN) r * (XPN) Gen1[m + 1]) );
}
}
// blk++;
return error;
}
// ======================================================================
// Compute the autocorrelation
void autocorrelation(int n, LPC_WORD const *ibuf, int nc, LPC_CORR *ac)
{
int i;
// Copy integer data to float -- speeds things up slightly...
LPC_FLOAT buf[ZWINMAX];
for (i = 0; i < n ; i++) buf[i] = (LPC_FLOAT) ibuf[i];
while (nc--)
{
LPC_CORR c = 0;
LPC_FLOAT const *lbuf = buf + nc; // Points to current sample + nc
#define CI(I) ( ((XPN)buf[I] * (XPN)lbuf[I]) )
//#define CI(I) (buf[I] * lbuf[I])
int istop = n - nc - 15; // Process 16 steps at a time for speed...
for (i = 0; i < istop; i += 16)
c = (LPN) ((XPN) c + CI(i+0) + CI(i+1) + CI(i+2) + CI(i+3) + CI(i+4) + CI(i+5) + CI(i+6) + CI(i+7)
+ CI(i+8) + CI(i+9) + CI(i+10)+ CI(i+11)+ CI(i+12)+ CI(i+13)+ CI(i+14)+ CI(i+15) );
istop = n - nc; // Process any remainder, one step at a time...
for (; i < istop; i++)
c = (LPN) ( (XPN) c + CI(i) );
ac[nc] = c;
#undef CI
}
}
// ======================================================================
// Add the autocorrelation for the end section of previous Window / start of current window
void AddAC (LPC_WORD const *hbuf, LPC_WORD const *ibuf, int nc, LPC_CORR *ac)
{
int i;
// Copy integer data to float -- speeds things up slightly...
LPC_FLOAT buf[PMAX*2];
int n = nc-1; // Number of samples is always one less than nc value
for (i = 0; i < n ; i++)
{
buf[i] = (LPC_FLOAT) hbuf[i];
buf[i + n] = (LPC_FLOAT) ibuf[i];
}
while (nc-- > 1)
{
LPC_CORR c = 0;
LPC_FLOAT const *lbuf = buf + nc; // Points to current sample + nc
int istop;
#define CI(I) ( ((XPN)buf[I] * (XPN)lbuf[I]) )
//#define CI(I) (buf[I] * lbuf[I])
istop = n - 15; // Process 16 steps at a time for speed...
i = n - nc;
for (; i < istop; i += 16)
c = (LPN) ( (XPN) c + CI(i+0) + CI(i+1) + CI(i+2) + CI(i+3) + CI(i+4) + CI(i+5) + CI(i+6) + CI(i+7)
+ CI(i+8) + CI(i+9) + CI(i+10)+ CI(i+11)+ CI(i+12)+ CI(i+13)+ CI(i+14)+ CI(i+15) );
istop = n; // Process any remainder, one step at a time...
for (; i < istop; i++)
c = (LPN) ( (XPN) c + (XPN) CI(i) );
ac[nc] = (LPN) ( (XPN) ac[nc] + (XPN) c );
#undef CI
}
}
// ======================================================================
static void LPCdecode(
LPC_PRAM const *ref, // in: [0...p-1] reflection coefficients
int nc, // in: number of coefficients
int n, // # of samples
LPC_WORD const *in, // [0...n-1] residual input
LPC_WORD *out) // out: [0...n-1] short-term signal
{
LPC_WORD s;
static LPC_WORD u[PMAX+1]; // NB: Intermediate values here can be out of range of AWORD
int i;
if (in == LAW_NULL) // Initialise?
{
for (i = 0; i < PMAX; i++) u[i] = 0;
return;
}
while (n--)
{
s = *in++;
#if REFINT == 1 //22.4 8gm
// ------------------------------------------------------
#define LPC_AN1(I) \
s -= SDIV(refp[I] * up[I], ISCALE_BITS); \
up[I+1] = up[I] + SDIV(refp[I] * s, ISCALE_BITS); \
// ------------------------------------------------------
LPC_PRAM const *refp = ref+nc-1;
LPC_WORD *up = u+nc-1;
while(refp >= ref)
{
LPC_AN1(0) ; LPC_AN1(-1); LPC_AN1(-2); LPC_AN1(-3);
LPC_AN1(-4); LPC_AN1(-5); LPC_AN1(-6); LPC_AN1(-7);
up -= 8; refp -= 8;
}
#undef LPC_AN1
#else
for (i = nc; i--;)
{
#if REFINT == 1
#if 1 // Use SDIV
long m;
m = ( ref[i] * u[i] );
s = ( s - SDIV(m, ISCALE_BITS) );
m = ( ref[i] * s );
u[i+1] = ( u[i] + SDIV(m, ISCALE_BITS) );
#else
s = s - ref[i] * u[i] / ISCALE;
u[i+1] = u[i] + (ref[i] * s / ISCALE);
#endif
#else // Use floating point, convert to int...
s = s - (int) (ref[i] * u[i]);
u[i+1] = u[i] + (int) (ref[i] * s);
#endif
}
#endif
*out++ = u[0] = s;
}
}
// ======================================================================
// UnLPC2() is called by UnLPC() -- process one LPCWIN sized chunk
long UnLPC2(LPC_WORD *OutBuf, LPC_WORD *InBuf, short bufsize, short nc, ULONG *Flags)
{
static LPC_WORD HistBuf[PMAX*2];
static LPC_CORR AcHist[HISTSIZE][PMAX+1];
static int HistNum;
LPC_PRAM ref[PMAX];
LPC_CORR ac[PMAX+1];
int i, k;
ULONG FlagMask = 1;
int zwin = ZWINMIN;
if (nc > zwin) zwin = ZWINMAX;
if (InBuf == LAW_NULL) // Initialise?
{
HistNum = 0;
for (i = 0; i < nc; i++) ref[i] = 0;
for (i = 0; i < PMAX*2; i++) HistBuf[i] = 0;
for (i = 0; i < PMAX+1; i++)
for (int j = 0; j < HISTSIZE; j++)
AcHist[j][i] = 0;
// LPCdecode(LAW_NULL, nc, 0, LAW_NULL, LAW_NULL);
LPCdecode(NULL, nc, 0, NULL, NULL);
return 0;
}
//if ((bufsize % zwin) != 0) return -3;
for (i = 0; i < bufsize; i += zwin)
{
#if HISTSIZE == 4
for (k = 0; k < nc+1; k++)
ac[k] = (XPN)AcHist[0][k] + (XPN)AcHist[1][k] + (XPN)AcHist[2][k] + (XPN)AcHist[3][k];
#else
for (k = 0; k < nc+1; k++)
{
ac[k] = 0;
for (int h = 0; h < HISTSIZE; h++)
ac[k] = (XPN)ac[k] + (XPN)AcHist[h][k];
}
#endif
// Decode...
if ((*Flags & FlagMask) == 0)
{
schur(ac, nc, ref);
LPCdecode(ref, nc, zwin, InBuf+i, OutBuf+i);
}
else
{
LPCinit(); // Re-initialise
for (int j = 0; j < zwin; j++) OutBuf[i+j] = InBuf[i+j]; // Copy input to output
}
FlagMask <<= 1;
// Update the AutoCorrelation history data...
AddAC(HistBuf, OutBuf+i, nc+1, AcHist[HistNum]); // Process overlap of prev. & current buffer
if (++HistNum == HISTSIZE) HistNum = 0; // Increment History counter, wrap-around if needed
autocorrelation(zwin, OutBuf+i, nc+1, AcHist[HistNum]); // Update AcHist with current buffer
for (k = 0; k < nc; k++) HistBuf[k] = OutBuf[i+k]; // Store beginning of current buffer for next AddAC()
}
return 0;
}
// ======================================================================
void LPCinit()
{
UnLPC2(LAW_NULL, LAW_NULL, 0, 0, (ULONG *)0);
}
// ======================================================================
long UnLPC(AWORD *OutBuf, AWORD *InBuf, short bufsize, short nc, ULONG *Flags)
{
long OutBits = 0;
LPC_WORD lInBuf[MAX_BUFSIZE], lOutBuf[MAX_BUFSIZE];
LPC_WORD *inp = lInBuf, *bufend = inp + bufsize, *outp = lOutBuf;
int i;
// Copy 16 bit data to 32 bits...
while (inp < bufend) *inp++ = *InBuf++;
inp = lInBuf;
short WinSize = LPCWIN;
if (WinSize > bufsize) WinSize = bufsize;
int WordsLeft = bufsize;
do {
if (WordsLeft < ZWINMIN)
{
for (i = 0; i < WordsLeft; i++)
outp[i] = inp[i];
}
else
{
long LPCout = UnLPC2(outp, inp, WinSize, nc, Flags);
if (LPCout < 0) return LPCout;
OutBits += LPCout;
}
inp += WinSize;
outp += WinSize;
WordsLeft -= WinSize;
} while (inp < bufend);
// Copy 32 bit data to 16 bits...
outp = lOutBuf; bufend = outp + bufsize;
while (outp < bufend)
*OutBuf++ = (AWORD) *outp++;
return 0;
}
// ======================================================================