ref: f18acee4a6206eb66894ba078df1f8708139fd48
dir: /celt/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 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 "pitch.h"
#include "os_support.h"
#include "modes.h"
#include "stack_alloc.h"
#include "mathops.h"
#include "celt_lpc.h"
static void find_best_pitch(opus_val32 *xcorr, opus_val16 *y, int len,
int max_pitch, int *best_pitch
#ifdef FIXED_POINT
, int yshift, opus_val32 maxcorr
#endif
)
{
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 = ADD32(Syy, SHR32(MULT16_16(y[j],y[j]), yshift));
for (i=0;i<max_pitch;i++)
{
if (xcorr[i]>0)
{
opus_val16 num;
opus_val32 xcorr16;
xcorr16 = EXTRACT16(VSHR32(xcorr[i], xshift));
#ifndef FIXED_POINT
/* Considering the range of xcorr16, this should avoid both underflows
and overflows (inf) when squaring xcorr16 */
xcorr16 *= 1e-12f;
#endif
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);
}
}
void pitch_downsample(celt_sig * OPUS_RESTRICT x[], opus_val16 * OPUS_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};
#ifdef FIXED_POINT
int shift;
opus_val32 maxabs = celt_maxabs32(x[0], len);
if (C==2)
{
opus_val32 maxabs_1 = celt_maxabs32(x[1], len);
maxabs = MAX32(maxabs, maxabs_1);
}
if (maxabs<1)
maxabs=1;
shift = celt_ilog2(maxabs)-10;
if (shift<0)
shift=0;
if (C==2)
shift++;
#endif
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]), shift);
x_lp[0] = SHR32(HALF32(HALF32(x[0][1])+x[0][0]), shift);
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]), shift);
x_lp[0] += SHR32(HALF32(HALF32(x[1][1])+x[1][0]), shift);
}
_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);
}
celt_fir(x_lp, lpc, x_lp, len>>1, 4, mem);
mem[0]=0;
lpc[0]=QCONST16(.8f,12);
celt_fir(x_lp, lpc, x_lp, len>>1, 1, mem);
}
void pitch_search(const opus_val16 * OPUS_RESTRICT x_lp, opus_val16 * OPUS_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);
#ifdef FIXED_POINT
opus_val32 maxcorr=1;
opus_val16 xmax, ymax;
int shift=0;
#endif
int offset;
SAVE_STACK;
celt_assert(len>0);
celt_assert(max_pitch>0);
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
xmax = celt_maxabs16(x_lp4, len>>2);
ymax = celt_maxabs16(y_lp4, lag>>2);
shift = celt_ilog2(MAX16(1, MAX16(xmax, ymax)))-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);
#ifdef FIXED_POINT
maxcorr = MAX32(maxcorr, sum);
#endif
}
find_best_pitch(xcorr, y_lp4, len>>2, max_pitch>>2, best_pitch
#ifdef FIXED_POINT
, 0, maxcorr
#endif
);
/* Finer search with 2x decimation */
#ifdef FIXED_POINT
maxcorr=1;
#endif
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);
#ifdef FIXED_POINT
maxcorr = MAX32(maxcorr, sum);
#endif
}
find_best_pitch(xcorr, y, len>>1, max_pitch>>1, best_pitch
#ifdef FIXED_POINT
, shift+1, maxcorr
#endif
);
/* 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;
opus_val16 thresh;
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;
thresh = MAX16(QCONST16(.3f,15), MULT16_16_Q15(QCONST16(.7f,15),g0)-cont);
/* Bias against very high pitch (very short period) to avoid false-positives
due to short-term correlation */
if (T1<3*minperiod)
thresh = MAX16(QCONST16(.4f,15), MULT16_16_Q15(QCONST16(.85f,15),g0)-cont);
else if (T1<2*minperiod)
thresh = MAX16(QCONST16(.5f,15), MULT16_16_Q15(QCONST16(.9f,15),g0)-cont);
if (g1 > thresh)
{
best_xy = xy;
best_yy = yy;
T = T1;
g = g1;
}
}
best_xy = MAX32(0, best_xy);
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;
}