filters.c

语音滤波源代码

      yi = EXTRACT16(PSHR32(SATURATE(x[i] + SHL32(mem[0],1),536870911),SIG_SHIFT));
      for (j=0;j<ord-1;j++)
      {
         mem[j] = MAC16_16(mem[j+1], num[j],xi);
      }
      mem[ord-1] = MULT16_16(num[ord-1],xi);
      y[i] = SHL32(EXTEND32(yi),SIG_SHIFT);
   }
}
#else
void fir_mem2(const spx_sig_t *x, const spx_coef_t *num, spx_sig_t *y, int N, int ord, spx_mem_t *mem)
{
   int i,j;
   spx_word32_t xi,yi;

   for (i=0;i<N;i++)
   {
      xi=SATURATE(x[i],805306368);
      yi = xi + SHL32(mem[0],2);
      for (j=0;j<ord-1;j++)
      {
         mem[j] = MAC16_32_Q15(mem[j+1], num[j],xi);
      }
      mem[ord-1] = MULT16_32_Q15(num[ord-1],xi);
      y[i] = SATURATE(yi,805306368);
   }
}
#endif
#endif








void syn_percep_zero(const spx_sig_t *xx, const spx_coef_t *ak, const spx_coef_t *awk1, const spx_coef_t *awk2, spx_sig_t *y, int N, int ord, char *stack)
{
   int i;
   VARDECL(spx_mem_t *mem);
   ALLOC(mem, ord, spx_mem_t);
   for (i=0;i<ord;i++)
     mem[i]=0;
   iir_mem2(xx, ak, y, N, ord, mem);
   for (i=0;i<ord;i++)
      mem[i]=0;
   filter_mem2(y, awk1, awk2, y, N, ord, mem);
}

void residue_percep_zero(const spx_sig_t *xx, const spx_coef_t *ak, const spx_coef_t *awk1, const spx_coef_t *awk2, spx_sig_t *y, int N, int ord, char *stack)
{
   int i;
   VARDECL(spx_mem_t *mem);
   ALLOC(mem, ord, spx_mem_t);
   for (i=0;i<ord;i++)
      mem[i]=0;
   filter_mem2(xx, ak, awk1, y, N, ord, mem);
   for (i=0;i<ord;i++)
     mem[i]=0;
   fir_mem2(y, awk2, y, N, ord, mem);
}

#ifndef OVERRIDE_COMPUTE_IMPULSE_RESPONSE
void compute_impulse_response(const spx_coef_t *ak, const spx_coef_t *awk1, const spx_coef_t *awk2, spx_word16_t *y, int N, int ord, char *stack)
{
   int i,j;
   spx_word16_t y1, ny1i, ny2i;
   VARDECL(spx_mem_t *mem1);
   VARDECL(spx_mem_t *mem2);
   ALLOC(mem1, ord, spx_mem_t);
   ALLOC(mem2, ord, spx_mem_t);
   
   y[0] = LPC_SCALING;
   for (i=0;i<ord;i++)
      y[i+1] = awk1[i];
   i++;
   for (;i<N;i++)
      y[i] = VERY_SMALL;
   
   for (i=0;i<ord;i++)
      mem1[i] = mem2[i] = 0;
   for (i=0;i<N;i++)
   {
      y1 = ADD16(y[i], EXTRACT16(PSHR32(mem1[0],LPC_SHIFT)));
      ny1i = NEG16(y1);
      y[i] = ADD16(SHL16(y1,1), EXTRACT16(PSHR32(mem2[0],LPC_SHIFT)));
      ny2i = NEG16(y[i]);
      for (j=0;j<ord-1;j++)
      {
         mem1[j] = MAC16_16(mem1[j+1], awk2[j],ny1i);
         mem2[j] = MAC16_16(mem2[j+1], ak[j],ny2i);
      }
      mem1[ord-1] = MULT16_16(awk2[ord-1],ny1i);
      mem2[ord-1] = MULT16_16(ak[ord-1],ny2i);
   }
}
#endif

void qmf_decomp(const spx_word16_t *xx, const spx_word16_t *aa, spx_sig_t *y1, spx_sig_t *y2, int N, int M, spx_word16_t *mem, char *stack)
{
   int i,j,k,M2;
   VARDECL(spx_word16_t *a);
   VARDECL(spx_word16_t *x);
   spx_word16_t *x2;
   
   ALLOC(a, M, spx_word16_t);
   ALLOC(x, N+M-1, spx_word16_t);
   x2=x+M-1;
   M2=M>>1;
   for (i=0;i<M;i++)
      a[M-i-1]= aa[i];

   for (i=0;i<M-1;i++)
      x[i]=mem[M-i-2];
   for (i=0;i<N;i++)
      x[i+M-1]=SATURATE(PSHR(xx[i],1),16383);
   for (i=0,k=0;i<N;i+=2,k++)
   {
      y1[k]=0;
      y2[k]=0;
      for (j=0;j<M2;j++)
      {
         y1[k]=ADD32(y1[k],SHR(MULT16_16(a[j],ADD16(x[i+j],x2[i-j])),1));
         y2[k]=SUB32(y2[k],SHR(MULT16_16(a[j],SUB16(x[i+j],x2[i-j])),1));
         j++;
         y1[k]=ADD32(y1[k],SHR(MULT16_16(a[j],ADD16(x[i+j],x2[i-j])),1));
         y2[k]=ADD32(y2[k],SHR(MULT16_16(a[j],SUB16(x[i+j],x2[i-j])),1));
      }
   }
   for (i=0;i<M-1;i++)
     mem[i]=SATURATE(PSHR(xx[N-i-1],1),16383);
}


/* By segher */
void fir_mem_up(const spx_sig_t *x, const spx_word16_t *a, spx_sig_t *y, int N, int M, spx_word32_t *mem, char *stack)
   /* assumptions:
      all odd x[i] are zero -- well, actually they are left out of the array now
      N and M are multiples of 4 */
{
   int i, j;
   VARDECL(spx_word16_t *xx);
   
   ALLOC(xx, M+N-1, spx_word16_t);

   for (i = 0; i < N/2; i++)
      xx[2*i] = SHR(x[N/2-1-i],SIG_SHIFT+1);
   for (i = 0; i < M - 1; i += 2)
      xx[N+i] = mem[i+1];

   for (i = 0; i < N; i += 4) {
      spx_sig_t y0, y1, y2, y3;
      spx_word16_t x0;

      y0 = y1 = y2 = y3 = 0;
      x0 = xx[N-4-i];

      for (j = 0; j < M; j += 4) {
         spx_word16_t x1;
         spx_word16_t a0, a1;

         a0 = a[j];
         a1 = a[j+1];
         x1 = xx[N-2+j-i];

         y0 = ADD32(y0,SHR(MULT16_16(a0, x1),1));
         y1 = ADD32(y1,SHR(MULT16_16(a1, x1),1));
         y2 = ADD32(y2,SHR(MULT16_16(a0, x0),1));
         y3 = ADD32(y3,SHR(MULT16_16(a1, x0),1));

         a0 = a[j+2];
         a1 = a[j+3];
         x0 = xx[N+j-i];

         y0 = ADD32(y0,SHR(MULT16_16(a0, x0),1));
         y1 = ADD32(y1,SHR(MULT16_16(a1, x0),1));
         y2 = ADD32(y2,SHR(MULT16_16(a0, x1),1));
         y3 = ADD32(y3,SHR(MULT16_16(a1, x1),1));
      }
      y[i] = y0;
      y[i+1] = y1;
      y[i+2] = y2;
      y[i+3] = y3;
   }

   for (i = 0; i < M - 1; i += 2)
      mem[i+1] = xx[i];
}

void comb_filter_mem_init (CombFilterMem *mem)
{
   mem->last_pitch=0;
   mem->last_pitch_gain[0]=mem->last_pitch_gain[1]=mem->last_pitch_gain[2]=0;
   mem->smooth_gain=1;
}

#ifdef FIXED_POINT
#define COMB_STEP 32767
#else
#define COMB_STEP 1.0
#endif

void comb_filter(
spx_sig_t *exc,          /*decoded excitation*/
spx_sig_t *new_exc,      /*enhanced excitation*/
spx_coef_t *ak,           /*LPC filter coefs*/
int p,               /*LPC order*/
int nsf,             /*sub-frame size*/
int pitch,           /*pitch period*/
spx_word16_t *pitch_gain,   /*pitch gain (3-tap)*/
spx_word16_t  comb_gain,    /*gain of comb filter*/
CombFilterMem *mem
)
{
   int i;
   spx_word16_t exc_energy=0, new_exc_energy=0;
   spx_word16_t gain;
   spx_word16_t step;
   spx_word16_t fact;

   /*Compute excitation amplitude prior to enhancement*/
   exc_energy = compute_rms(exc, nsf);
   /*for (i=0;i<nsf;i++)
     exc_energy+=((float)exc[i])*exc[i];*/

   /*Some gain adjustment if pitch is too high or if unvoiced*/
#ifdef FIXED_POINT
   {
      spx_word16_t g = gain_3tap_to_1tap(pitch_gain)+gain_3tap_to_1tap(mem->last_pitch_gain);
      if (g > 166)
         comb_gain = MULT16_16_Q15(DIV32_16(SHL32(EXTEND32(165),15),g), comb_gain);
      if (g < 64)
         comb_gain = MULT16_16_Q15(SHL16(g, 9), comb_gain);
   }
#else
   {
      float g=0;
      g = GAIN_SCALING_1*.5*(gain_3tap_to_1tap(pitch_gain)+gain_3tap_to_1tap(mem->last_pitch_gain));
      if (g>1.3)
         comb_gain*=1.3/g;
      if (g<.5)
         comb_gain*=2.*g;
   }
#endif
   step = DIV32(COMB_STEP, nsf);
   fact=0;

   /*Apply pitch comb-filter (filter out noise between pitch harmonics)*/
   for (i=0;i<nsf;i++)
   {
      spx_word32_t exc1, exc2;

      fact = ADD16(fact,step);
      
      exc1 = SHL32(MULT16_32_Q15(SHL16(pitch_gain[0],7),exc[i-pitch+1]) +
                 MULT16_32_Q15(SHL16(pitch_gain[1],7),exc[i-pitch]) +
                 MULT16_32_Q15(SHL16(pitch_gain[2],7),exc[i-pitch-1]) , 2);
      exc2 = SHL32(MULT16_32_Q15(SHL16(mem->last_pitch_gain[0],7),exc[i-mem->last_pitch+1]) +
                 MULT16_32_Q15(SHL16(mem->last_pitch_gain[1],7),exc[i-mem->last_pitch]) +
                 MULT16_32_Q15(SHL16(mem->last_pitch_gain[2],7),exc[i-mem->last_pitch-1]),2);

      new_exc[i] = exc[i] + MULT16_32_Q15(comb_gain, ADD32(MULT16_32_Q15(fact,exc1), MULT16_32_Q15(SUB16(COMB_STEP,fact), exc2)));
   }

   mem->last_pitch_gain[0] = pitch_gain[0];
   mem->last_pitch_gain[1] = pitch_gain[1];
   mem->last_pitch_gain[2] = pitch_gain[2];
   mem->last_pitch = pitch;

   /*Amplitude after enhancement*/
   new_exc_energy = compute_rms(new_exc, nsf);

   if (exc_energy > new_exc_energy)
      exc_energy = new_exc_energy;
   
   gain = DIV32_16(SHL32(EXTEND32(exc_energy),15),ADD16(1,new_exc_energy));

#ifdef FIXED_POINT
   if (gain < 16384)
      gain = 16384;
#else
   if (gain < .5)
      gain=.5;
#endif

#ifdef FIXED_POINT
   for (i=0;i<nsf;i++)
   {
      mem->smooth_gain = ADD16(MULT16_16_Q15(31457,mem->smooth_gain), MULT16_16_Q15(1311,gain));
      new_exc[i] = MULT16_32_Q15(mem->smooth_gain, new_exc[i]);
   }
#else
   for (i=0;i<nsf;i++)
   {
      mem->smooth_gain = .96*mem->smooth_gain + .04*gain;
      new_exc[i] *= mem->smooth_gain;
   }
#endif
}