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[2])
{
   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};
   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;
}