ref: bfebf824addf8027ae60dee6ef271980b283a9c1
dir: /celt/celt_lpc.c/
/* Copyright (c) 2009-2010 Xiph.Org Foundation
Written by Jean-Marc Valin */
/*
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
- Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "celt_lpc.h"
#include "stack_alloc.h"
#include "mathops.h"
#include "pitch.h"
void _celt_lpc(
opus_val16 *_lpc, /* out: [0...p-1] LPC coefficients */
const opus_val32 *ac, /* in: [0...p] autocorrelation values */
int p
)
{
int i, j;
opus_val32 r;
opus_val32 error = ac[0];
#ifdef FIXED_POINT
opus_val32 lpc[LPC_ORDER];
#else
float *lpc = _lpc;
#endif
OPUS_CLEAR(lpc, p);
#ifdef FIXED_POINT
if (ac[0] != 0)
#else
if (ac[0] > 1e-10f)
#endif
{
for (i = 0; i < p; i++) {
/* Sum up this iteration's reflection coefficient */
opus_val32 rr = 0;
for (j = 0; j < i; j++)
rr += MULT32_32_Q31(lpc[j],ac[i - j]);
rr += SHR32(ac[i + 1],6);
r = -frac_div32(SHL32(rr,6), error);
/* Update LPC coefficients and total error */
lpc[i] = SHR32(r,6);
for (j = 0; j < (i+1)>>1; j++)
{
opus_val32 tmp1, tmp2;
tmp1 = lpc[j];
tmp2 = lpc[i-1-j];
lpc[j] = tmp1 + MULT32_32_Q31(r,tmp2);
lpc[i-1-j] = tmp2 + MULT32_32_Q31(r,tmp1);
}
error = error - MULT32_32_Q31(MULT32_32_Q31(r,r),error);
/* Bail out once we get 30 dB gain */
#ifdef FIXED_POINT
if (error<=SHR32(ac[0],10))
break;
#else
if (error<=.001f*ac[0])
break;
#endif
}
}
#ifdef FIXED_POINT
{
/* Convert the int32 lpcs to int16 and ensure there are no wrap-arounds.
This reuses the logic in silk_LPC_fit() and silk_bwexpander_32(). Any bug
fixes should also be applied there. */
int iter, idx = 0;
opus_val32 maxabs, absval, chirp_Q16, chirp_minus_one_Q16;
for (iter = 0; iter < 10; iter++) {
maxabs = 0;
for (i = 0; i < p; i++) {
absval = ABS32(lpc[i]);
if (absval > maxabs) {
maxabs = absval;
idx = i;
}
}
maxabs = PSHR32(maxabs, 13); /* Q25->Q12 */
if (maxabs > 32767) {
maxabs = MIN32(maxabs, 163838);
chirp_Q16 = QCONST32(0.999, 16) - DIV32(SHL32(maxabs - 32767, 14),
SHR32(MULT32_32_32(maxabs, idx + 1), 2));
chirp_minus_one_Q16 = chirp_Q16 - 65536;
/* Apply bandwidth expansion. */
for (i = 0; i < p - 1; i++) {
lpc[i] = MULT32_32_Q16(chirp_Q16, lpc[i]);
chirp_Q16 += PSHR32(MULT32_32_32(chirp_Q16, chirp_minus_one_Q16), 16);
}
lpc[p - 1] = MULT32_32_Q16(chirp_Q16, lpc[p - 1]);
} else {
break;
}
}
if (iter == 10) {
/* If the coeffs still do not fit into the 16 bit range after 10 iterations,
fall back to the A(z)=1 filter. */
OPUS_CLEAR(lpc, p);
_lpc[0] = 4096; /* Q12 */
} else {
for (i = 0; i < p; i++) {
_lpc[i] = EXTRACT16(PSHR32(lpc[i], 13)); /* Q25->Q12 */
}
}
}
#endif
}
void celt_fir_c(
const opus_val16 *x,
const opus_val16 *num,
opus_val16 *y,
int N,
int ord,
int arch)
{
int i,j;
VARDECL(opus_val16, rnum);
SAVE_STACK;
celt_assert(x != y);
ALLOC(rnum, ord, opus_val16);
for(i=0;i<ord;i++)
rnum[i] = num[ord-i-1];
for (i=0;i<N-3;i+=4)
{
opus_val32 sum[4];
sum[0] = SHL32(EXTEND32(x[i ]), SIG_SHIFT);
sum[1] = SHL32(EXTEND32(x[i+1]), SIG_SHIFT);
sum[2] = SHL32(EXTEND32(x[i+2]), SIG_SHIFT);
sum[3] = SHL32(EXTEND32(x[i+3]), SIG_SHIFT);
xcorr_kernel(rnum, x+i-ord, sum, ord, arch);
y[i ] = ROUND16(sum[0], SIG_SHIFT);
y[i+1] = ROUND16(sum[1], SIG_SHIFT);
y[i+2] = ROUND16(sum[2], SIG_SHIFT);
y[i+3] = ROUND16(sum[3], SIG_SHIFT);
}
for (;i<N;i++)
{
opus_val32 sum = SHL32(EXTEND32(x[i]), SIG_SHIFT);
for (j=0;j<ord;j++)
sum = MAC16_16(sum,rnum[j],x[i+j-ord]);
y[i] = ROUND16(sum, SIG_SHIFT);
}
RESTORE_STACK;
}
void celt_iir(const opus_val32 *_x,
const opus_val16 *den,
opus_val32 *_y,
int N,
int ord,
opus_val16 *mem,
int arch)
{
#ifdef SMALL_FOOTPRINT
int i,j;
(void)arch;
for (i=0;i<N;i++)
{
opus_val32 sum = _x[i];
for (j=0;j<ord;j++)
{
sum -= MULT16_16(den[j],mem[j]);
}
for (j=ord-1;j>=1;j--)
{
mem[j]=mem[j-1];
}
mem[0] = SROUND16(sum, SIG_SHIFT);
_y[i] = sum;
}
#else
int i,j;
VARDECL(opus_val16, rden);
VARDECL(opus_val16, y);
SAVE_STACK;
celt_assert((ord&3)==0);
ALLOC(rden, ord, opus_val16);
ALLOC(y, N+ord, opus_val16);
for(i=0;i<ord;i++)
rden[i] = den[ord-i-1];
for(i=0;i<ord;i++)
y[i] = -mem[ord-i-1];
for(;i<N+ord;i++)
y[i]=0;
for (i=0;i<N-3;i+=4)
{
/* Unroll by 4 as if it were an FIR filter */
opus_val32 sum[4];
sum[0]=_x[i];
sum[1]=_x[i+1];
sum[2]=_x[i+2];
sum[3]=_x[i+3];
xcorr_kernel(rden, y+i, sum, ord, arch);
/* Patch up the result to compensate for the fact that this is an IIR */
y[i+ord ] = -SROUND16(sum[0],SIG_SHIFT);
_y[i ] = sum[0];
sum[1] = MAC16_16(sum[1], y[i+ord ], den[0]);
y[i+ord+1] = -SROUND16(sum[1],SIG_SHIFT);
_y[i+1] = sum[1];
sum[2] = MAC16_16(sum[2], y[i+ord+1], den[0]);
sum[2] = MAC16_16(sum[2], y[i+ord ], den[1]);
y[i+ord+2] = -SROUND16(sum[2],SIG_SHIFT);
_y[i+2] = sum[2];
sum[3] = MAC16_16(sum[3], y[i+ord+2], den[0]);
sum[3] = MAC16_16(sum[3], y[i+ord+1], den[1]);
sum[3] = MAC16_16(sum[3], y[i+ord ], den[2]);
y[i+ord+3] = -SROUND16(sum[3],SIG_SHIFT);
_y[i+3] = sum[3];
}
for (;i<N;i++)
{
opus_val32 sum = _x[i];
for (j=0;j<ord;j++)
sum -= MULT16_16(rden[j],y[i+j]);
y[i+ord] = SROUND16(sum,SIG_SHIFT);
_y[i] = sum;
}
for(i=0;i<ord;i++)
mem[i] = _y[N-i-1];
RESTORE_STACK;
#endif
}
int _celt_autocorr(
const opus_val16 *x, /* in: [0...n-1] samples x */
opus_val32 *ac, /* out: [0...lag-1] ac values */
const opus_val16 *window,
int overlap,
int lag,
int n,
int arch
)
{
opus_val32 d;
int i, k;
int fastN=n-lag;
int shift;
const opus_val16 *xptr;
VARDECL(opus_val16, xx);
SAVE_STACK;
ALLOC(xx, n, opus_val16);
celt_assert(n>0);
celt_assert(overlap>=0);
if (overlap == 0)
{
xptr = x;
} else {
for (i=0;i<n;i++)
xx[i] = x[i];
for (i=0;i<overlap;i++)
{
xx[i] = MULT16_16_Q15(x[i],window[i]);
xx[n-i-1] = MULT16_16_Q15(x[n-i-1],window[i]);
}
xptr = xx;
}
shift=0;
#ifdef FIXED_POINT
{
opus_val32 ac0;
ac0 = 1+(n<<7);
if (n&1) ac0 += SHR32(MULT16_16(xptr[0],xptr[0]),9);
for(i=(n&1);i<n;i+=2)
{
ac0 += SHR32(MULT16_16(xptr[i],xptr[i]),9);
ac0 += SHR32(MULT16_16(xptr[i+1],xptr[i+1]),9);
}
shift = celt_ilog2(ac0)-30+10;
shift = (shift)/2;
if (shift>0)
{
for(i=0;i<n;i++)
xx[i] = PSHR32(xptr[i], shift);
xptr = xx;
} else
shift = 0;
}
#endif
celt_pitch_xcorr(xptr, xptr, ac, fastN, lag+1, arch);
for (k=0;k<=lag;k++)
{
for (i = k+fastN, d = 0; i < n; i++)
d = MAC16_16(d, xptr[i], xptr[i-k]);
ac[k] += d;
}
#ifdef FIXED_POINT
shift = 2*shift;
if (shift<=0)
ac[0] += SHL32((opus_int32)1, -shift);
if (ac[0] < 268435456)
{
int shift2 = 29 - EC_ILOG(ac[0]);
for (i=0;i<=lag;i++)
ac[i] = SHL32(ac[i], shift2);
shift -= shift2;
} else if (ac[0] >= 536870912)
{
int shift2=1;
if (ac[0] >= 1073741824)
shift2++;
for (i=0;i<=lag;i++)
ac[i] = SHR32(ac[i], shift2);
shift += shift2;
}
#endif
RESTORE_STACK;
return shift;
}