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);

}

#if 0 /* This is a simple version of the pitch correlation that should work
         well on DSPs like Blackfin and TI C5x/C6x */

static void pitch_xcorr(opus_val16 *x, opus_val16 *y, opus_val32 *xcorr, int len, int max_pitch
#ifdef FIXED_POINT
      ,opus_val32 *maxval
#endif
      )
{
   int i, j;
#ifdef FIXED_POINT
   opus_val32 maxcorr=1;
#endif
   for (i=0;i<max_pitch;i++)
   {
      opus_val32 sum = 0;
      for (j=0;j<len;j++)
         sum = MAC16_16(sum, x[j],y[i+j]);
      xcorr[i] = MAX32(-1, sum);
#ifdef FIXED_POINT
      maxcorr = MAX32(maxcorr, sum);
#endif
   }
#ifdef FIXED_POINT
   *maxval = maxcorr;
#endif
}

#else /* Unrolled version of the pitch correlation -- runs faster on x86 and ARM */

static void pitch_xcorr(opus_val16 *_x, opus_val16 *_y, opus_val32 *xcorr, int len, int max_pitch
#ifdef FIXED_POINT
      ,opus_val32 *maxval
#endif
      )
{
   int i,j;
#ifdef FIXED_POINT
   opus_val32 maxcorr=1;
#endif
   /* Truncate slightly if len is not a multiple of 4. */
   len -= len&3;
   for (i=0;i<max_pitch-3;i+=4)
   {
      /* Compute correlation*/
      /*corr[nb_pitch-1-i]=inner_prod(x, _y+i, len);*/
      opus_val32 sum1=0;
      opus_val32 sum2=0;
      opus_val32 sum3=0;
      opus_val32 sum4=0;
      const opus_val16 *y = _y+i;
      const opus_val16 *x = _x;
      opus_val16 y0, y1, y2, y3;
      /*y0=y[0];y1=y[1];y2=y[2];y3=y[3];*/
      y0=*y++;
      y1=*y++;
      y2=*y++;
      for (j=0;j<len;j+=4)
      {
         opus_val16 tmp;
         tmp = *x++;
         y3=*y++;
         sum1 = MAC16_16(sum1,tmp,y0);
         sum2 = MAC16_16(sum2,tmp,y1);
         sum3 = MAC16_16(sum3,tmp,y2);
         sum4 = MAC16_16(sum4,tmp,y3);
         tmp=*x++;
         y0=*y++;
         sum1 = MAC16_16(sum1,tmp,y1);
         sum2 = MAC16_16(sum2,tmp,y2);
         sum3 = MAC16_16(sum3,tmp,y3);
         sum4 = MAC16_16(sum4,tmp,y0);
         tmp=*x++;
         y1=*y++;
         sum1 = MAC16_16(sum1,tmp,y2);
         sum2 = MAC16_16(sum2,tmp,y3);
         sum3 = MAC16_16(sum3,tmp,y0);
         sum4 = MAC16_16(sum4,tmp,y1);
         tmp=*x++;
         y2=*y++;
         sum1 = MAC16_16(sum1,tmp,y3);
         sum2 = MAC16_16(sum2,tmp,y0);
         sum3 = MAC16_16(sum3,tmp,y1);
         sum4 = MAC16_16(sum4,tmp,y2);
      }
      xcorr[i]=MAX32(-1, sum1);
      xcorr[i+1]=MAX32(-1, sum2);
      xcorr[i+2]=MAX32(-1, sum3);
      xcorr[i+3]=MAX32(-1, sum4);
#ifdef FIXED_POINT
      sum1 = MAX32(sum1, sum2);
      sum3 = MAX32(sum3, sum4);
      sum1 = MAX32(sum1, sum3);
      maxcorr = MAX32(maxcorr, sum1);
#endif
   }
   /* In case max_pitch isn't a multiple of 4, do non-unrolled version. */
   for (;i<max_pitch;i++)
   {
      opus_val32 sum = 0;
      for (j=0;j<len;j++)
         sum = MAC16_16(sum, _x[j],_y[i+j]);
      xcorr[i] = MAX32(-1, sum);
#ifdef FIXED_POINT
      maxcorr = MAX32(maxcorr, sum);
#endif
   }
#ifdef FIXED_POINT
   *maxval = maxcorr;
#endif
}

#endif
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;
   opus_val32 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(MAX32(1, MAX32(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 */

   pitch_xcorr(x_lp4, y_lp4, xcorr, len>>2, max_pitch>>2
#ifdef FIXED_POINT
         ,&maxcorr
#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;
}