ref: 2b98bdf53253b6b85fffe7f1bfa9141ae9b09e61
dir: /libcelt/pitch.c/
/* Copyright (c) 2007-2008 CSIRO
Copyright (c) 2007-2009 Xiph.Org Foundation
Written by Jean-Marc Valin */
/**
@file pitch.c
@brief Pitch analysis
*/
/*
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 FOUNDATION 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 "pitch.h"
#include "os_support.h"
#include "modes.h"
#include "stack_alloc.h"
#include "mathops.h"
static void find_best_pitch(opus_val32 *xcorr, opus_val32 maxcorr, opus_val16 *y,
int yshift, int len, int max_pitch, int *best_pitch)
{
int i, j;
opus_val32 Syy=1;
opus_val16 best_num[2];
opus_val32 best_den[2];
#ifdef FIXED_POINT
int xshift;
xshift = celt_ilog2(maxcorr)-14;
#endif
best_num[0] = -1;
best_num[1] = -1;
best_den[0] = 0;
best_den[1] = 0;
best_pitch[0] = 0;
best_pitch[1] = 1;
for (j=0;j<len;j++)
Syy = MAC16_16(Syy, y[j],y[j]);
for (i=0;i<max_pitch;i++)
{
if (xcorr[i]>0)
{
opus_val16 num;
opus_val32 xcorr16;
xcorr16 = EXTRACT16(VSHR32(xcorr[i], xshift));
num = MULT16_16_Q15(xcorr16,xcorr16);
if (MULT16_32_Q15(num,best_den[1]) > MULT16_32_Q15(best_num[1],Syy))
{
if (MULT16_32_Q15(num,best_den[0]) > MULT16_32_Q15(best_num[0],Syy))
{
best_num[1] = best_num[0];
best_den[1] = best_den[0];
best_pitch[1] = best_pitch[0];
best_num[0] = num;
best_den[0] = Syy;
best_pitch[0] = i;
} else {
best_num[1] = num;
best_den[1] = Syy;
best_pitch[1] = i;
}
}
}
Syy += SHR32(MULT16_16(y[i+len],y[i+len]),yshift) - SHR32(MULT16_16(y[i],y[i]),yshift);
Syy = MAX32(1, Syy);
}
}
#include "plc.h"
void pitch_downsample(celt_sig * restrict x[], opus_val16 * restrict x_lp,
int len, int _C)
{
int i;
opus_val32 ac[5];
opus_val16 tmp=Q15ONE;
opus_val16 lpc[4], mem[4]={0,0,0,0};
const int C = CHANNELS(_C);
for (i=1;i<len>>1;i++)
x_lp[i] = SHR32(HALF32(HALF32(x[0][(2*i-1)]+x[0][(2*i+1)])+x[0][2*i]), SIG_SHIFT+3);
x_lp[0] = SHR32(HALF32(HALF32(x[0][1])+x[0][0]), SIG_SHIFT+3);
if (C==2)
{
for (i=1;i<len>>1;i++)
x_lp[i] += SHR32(HALF32(HALF32(x[1][(2*i-1)]+x[1][(2*i+1)])+x[1][2*i]), SIG_SHIFT+3);
x_lp[0] += SHR32(HALF32(HALF32(x[1][1])+x[1][0]), SIG_SHIFT+3);
}
_celt_autocorr(x_lp, ac, NULL, 0,
4, len>>1);
/* Noise floor -40 dB */
#ifdef FIXED_POINT
ac[0] += SHR32(ac[0],13);
#else
ac[0] *= 1.0001f;
#endif
/* Lag windowing */
for (i=1;i<=4;i++)
{
/*ac[i] *= exp(-.5*(2*M_PI*.002*i)*(2*M_PI*.002*i));*/
#ifdef FIXED_POINT
ac[i] -= MULT16_32_Q15(2*i*i, ac[i]);
#else
ac[i] -= ac[i]*(.008f*i)*(.008f*i);
#endif
}
_celt_lpc(lpc, ac, 4);
for (i=0;i<4;i++)
{
tmp = MULT16_16_Q15(QCONST16(.9f,15), tmp);
lpc[i] = MULT16_16_Q15(lpc[i], tmp);
}
fir(x_lp, lpc, x_lp, len>>1, 4, mem);
mem[0]=0;
lpc[0]=QCONST16(.8f,12);
fir(x_lp, lpc, x_lp, len>>1, 1, mem);
}
void pitch_search(const opus_val16 * restrict x_lp, opus_val16 * restrict y,
int len, int max_pitch, int *pitch)
{
int i, j;
int lag;
int best_pitch[2]={0,0};
VARDECL(opus_val16, x_lp4);
VARDECL(opus_val16, y_lp4);
VARDECL(opus_val32, xcorr);
opus_val32 maxcorr=1;
int offset;
int shift=0;
SAVE_STACK;
lag = len+max_pitch;
ALLOC(x_lp4, len>>2, opus_val16);
ALLOC(y_lp4, lag>>2, opus_val16);
ALLOC(xcorr, max_pitch>>1, opus_val32);
/* Downsample by 2 again */
for (j=0;j<len>>2;j++)
x_lp4[j] = x_lp[2*j];
for (j=0;j<lag>>2;j++)
y_lp4[j] = y[2*j];
#ifdef FIXED_POINT
shift = celt_ilog2(MAX16(1, MAX16(celt_maxabs16(x_lp4, len>>2), celt_maxabs16(y_lp4, lag>>2))))-11;
if (shift>0)
{
for (j=0;j<len>>2;j++)
x_lp4[j] = SHR16(x_lp4[j], shift);
for (j=0;j<lag>>2;j++)
y_lp4[j] = SHR16(y_lp4[j], shift);
/* Use double the shift for a MAC */
shift *= 2;
} else {
shift = 0;
}
#endif
/* Coarse search with 4x decimation */
for (i=0;i<max_pitch>>2;i++)
{
opus_val32 sum = 0;
for (j=0;j<len>>2;j++)
sum = MAC16_16(sum, x_lp4[j],y_lp4[i+j]);
xcorr[i] = MAX32(-1, sum);
maxcorr = MAX32(maxcorr, sum);
}
find_best_pitch(xcorr, maxcorr, y_lp4, 0, len>>2, max_pitch>>2, best_pitch);
/* Finer search with 2x decimation */
maxcorr=1;
for (i=0;i<max_pitch>>1;i++)
{
opus_val32 sum=0;
xcorr[i] = 0;
if (abs(i-2*best_pitch[0])>2 && abs(i-2*best_pitch[1])>2)
continue;
for (j=0;j<len>>1;j++)
sum += SHR32(MULT16_16(x_lp[j],y[i+j]), shift);
xcorr[i] = MAX32(-1, sum);
maxcorr = MAX32(maxcorr, sum);
}
find_best_pitch(xcorr, maxcorr, y, shift, len>>1, max_pitch>>1, best_pitch);
/* Refine by pseudo-interpolation */
if (best_pitch[0]>0 && best_pitch[0]<(max_pitch>>1)-1)
{
opus_val32 a, b, c;
a = xcorr[best_pitch[0]-1];
b = xcorr[best_pitch[0]];
c = xcorr[best_pitch[0]+1];
if ((c-a) > MULT16_32_Q15(QCONST16(.7f,15),b-a))
offset = 1;
else if ((a-c) > MULT16_32_Q15(QCONST16(.7f,15),b-c))
offset = -1;
else
offset = 0;
} else {
offset = 0;
}
*pitch = 2*best_pitch[0]-offset;
RESTORE_STACK;
}
static const int second_check[16] = {0, 0, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2};
opus_val16 remove_doubling(opus_val16 *x, int maxperiod, int minperiod,
int N, int *_T0, int prev_period, opus_val16 prev_gain)
{
int k, i, T, T0;
opus_val16 g, g0;
opus_val16 pg;
opus_val32 xy,xx,yy;
opus_val32 xcorr[3];
opus_val32 best_xy, best_yy;
int offset;
int minperiod0;
minperiod0 = minperiod;
maxperiod /= 2;
minperiod /= 2;
*_T0 /= 2;
prev_period /= 2;
N /= 2;
x += maxperiod;
if (*_T0>=maxperiod)
*_T0=maxperiod-1;
T = T0 = *_T0;
xx=xy=yy=0;
for (i=0;i<N;i++)
{
xy = MAC16_16(xy, x[i], x[i-T0]);
xx = MAC16_16(xx, x[i], x[i]);
yy = MAC16_16(yy, x[i-T0],x[i-T0]);
}
best_xy = xy;
best_yy = yy;
#ifdef FIXED_POINT
{
opus_val32 x2y2;
int sh, t;
x2y2 = 1+HALF32(MULT32_32_Q31(xx,yy));
sh = celt_ilog2(x2y2)>>1;
t = VSHR32(x2y2, 2*(sh-7));
g = g0 = VSHR32(MULT16_32_Q15(celt_rsqrt_norm(t), xy),sh+1);
}
#else
g = g0 = xy/celt_sqrt(1+xx*yy);
#endif
/* Look for any pitch at T/k */
for (k=2;k<=15;k++)
{
int T1, T1b;
opus_val16 g1;
opus_val16 cont=0;
T1 = (2*T0+k)/(2*k);
if (T1 < minperiod)
break;
/* Look for another strong correlation at T1b */
if (k==2)
{
if (T1+T0>maxperiod)
T1b = T0;
else
T1b = T0+T1;
} else
{
T1b = (2*second_check[k]*T0+k)/(2*k);
}
xy=yy=0;
for (i=0;i<N;i++)
{
xy = MAC16_16(xy, x[i], x[i-T1]);
yy = MAC16_16(yy, x[i-T1], x[i-T1]);
xy = MAC16_16(xy, x[i], x[i-T1b]);
yy = MAC16_16(yy, x[i-T1b], x[i-T1b]);
}
#ifdef FIXED_POINT
{
opus_val32 x2y2;
int sh, t;
x2y2 = 1+MULT32_32_Q31(xx,yy);
sh = celt_ilog2(x2y2)>>1;
t = VSHR32(x2y2, 2*(sh-7));
g1 = VSHR32(MULT16_32_Q15(celt_rsqrt_norm(t), xy),sh+1);
}
#else
g1 = xy/celt_sqrt(1+2.f*xx*1.f*yy);
#endif
if (abs(T1-prev_period)<=1)
cont = prev_gain;
else if (abs(T1-prev_period)<=2 && 5*k*k < T0)
cont = HALF32(prev_gain);
else
cont = 0;
if (g1 > QCONST16(.3f,15) + MULT16_16_Q15(QCONST16(.4f,15),g0)-cont)
{
best_xy = xy;
best_yy = yy;
T = T1;
g = g1;
}
}
if (best_yy <= best_xy)
pg = Q15ONE;
else
pg = SHR32(frac_div32(best_xy,best_yy+1),16);
for (k=0;k<3;k++)
{
int T1 = T+k-1;
xy = 0;
for (i=0;i<N;i++)
xy = MAC16_16(xy, x[i], x[i-T1]);
xcorr[k] = xy;
}
if ((xcorr[2]-xcorr[0]) > MULT16_32_Q15(QCONST16(.7f,15),xcorr[1]-xcorr[0]))
offset = 1;
else if ((xcorr[0]-xcorr[2]) > MULT16_32_Q15(QCONST16(.7f,15),xcorr[1]-xcorr[2]))
offset = -1;
else
offset = 0;
if (pg > g)
pg = g;
*_T0 = 2*T+offset;
if (*_T0<minperiod0)
*_T0=minperiod0;
return pg;
}