www.pudn.com > g729_audio_encode.rar > pitch.c
/*
ITU-T G.729 Speech Coder ANSI-C Source Code
Version 3.3 Last modified: December 26, 1995
Copyright (c) 1996,
AT&T, France Telecom, NTT, Universite de Sherbrooke, Lucent Technologies
All rights reserved.
*/
/*---------------------------------------------------------------------------*
* procedure Pitch_ol *
* ~~~~~~~~~~~~~~~~~~ *
* Compute the open loop pitch lag. *
* *
*---------------------------------------------------------------------------*/
#include "typedef.h"
#include "basic_op.h"
#include "oper_32b.h"
#include "ld8k.h"
#include "tab_ld8k.h"
/* local function */
static Word16 Lag_max( /* output: lag found */
Word16 signal[], /* input : signal used to compute the open loop pitch */
Word16 L_frame, /* input : length of frame to compute pitch */
Word16 lag_max, /* input : maximum lag */
Word16 lag_min, /* input : minimum lag */
Word16 *cor_max); /* output: normalized correlation of selected lag */
Word16 Pitch_ol( /* output: open loop pitch lag */
Word16 signal[], /* input : signal used to compute the open loop pitch */
/* signal[-pit_max] to signal[-1] should be known */
Word16 pit_min, /* input : minimum pitch lag */
Word16 pit_max, /* input : maximum pitch lag */
Word16 L_frame /* input : length of frame to compute pitch */
)
{
Word16 i, j;
Word16 max1, max2, max3;
Word16 p_max1, p_max2, p_max3;
Word32 t0, L_temp;
/* Scaled signal */
Word16 scaled_signal[L_FRAME+PIT_MAX];
Word16 *scal_sig;
scal_sig = &scaled_signal[pit_max];
/*--------------------------------------------------------*
* Verification for risk of overflow. *
*--------------------------------------------------------*/
Overflow = 0;
t0 = 0;
for(i= -pit_max; i< L_frame; i++)
t0 = L_mac(t0, signal[i], signal[i]);
/*--------------------------------------------------------*
* Scaling of input signal. *
* *
* if Overflow -> scal_sig[i] = signal[i]>>3 *
* else if t0 < 1^20 -> scal_sig[i] = signal[i]<<3 *
* else -> scal_sig[i] = signal[i] *
*--------------------------------------------------------*/
if(Overflow == 1)
{
for(i=-pit_max; i= lag_min; i--)
{
p = signal;
p1 = &signal[-i];
t0 = 0;
for (j=0; j= 0L)
{
max = t0;
p_max = i;
}
}
/* compute energy */
t0 = 0;
p = &signal[-p_max];
for(i=0; i= 0)
{
max = corr[i];
lag = i;
}
}
/* If first subframe and lag > 84 do not search fractional pitch */
if( (i_subfr == 0) && (sub(lag, 84) > 0) )
{
*pit_frac = 0;
return(lag);
}
/* Test the fractions around T0 and choose the one which maximizes */
/* the interpolated normalized correlation. */
max = Interpol_3(&corr[lag], -2);
frac = -2;
for (i = -1; i <= 2; i++)
{
corr_int = Interpol_3(&corr[lag], i);
if (sub(corr_int, max) > 0)
{
max = corr_int;
frac = i;
}
}
/* limit the fraction value between -1 and 1 */
if (sub(frac, -2) == 0)
{
frac = 1;
lag = sub(lag, 1);
}
if (sub(frac, 2) == 0)
{
frac = -1;
lag = add(lag, 1);
}
*pit_frac = frac;
return(lag);
}
/*---------------------------------------------------------------------------*
* Function Norm_Corr() *
* ~~~~~~~~~~~~~~~~~~~~ *
* Find the normalized correlation between the target vector and the *
* filtered past excitation. *
*---------------------------------------------------------------------------*
* Input arguments: *
* exc[] : excitation buffer *
* xn[] : target vector *
* h[] : impulse response of synthesis and weighting filters (Q12) *
* L_subfr : Length of subframe *
* t_min : minimum value of pitch lag. *
* t_max : maximum value of pitch lag. *
* *
* Output arguments: *
* corr_norm[]: normalized correlation (correlation between target and *
* filtered excitation divided by the square root of *
* energy of filtered excitation) *
*--------------------------------------------------------------------------*/
static void Norm_Corr(Word16 exc[], Word16 xn[], Word16 h[], Word16 L_subfr,
Word16 t_min, Word16 t_max, Word16 corr_norm[])
{
Word16 i,j,k;
Word16 corr_h, corr_l, norm_h, norm_l;
Word32 s, L_temp;
Word16 excf[L_SUBFR];
Word16 scaling, h_fac, *s_excf, scaled_excf[L_SUBFR];
k = negate(t_min);
/* compute the filtered excitation for the first delay t_min */
Convolve(&exc[k], h, excf, L_subfr);
/* scaled "excf[]" to avoid overflow */
for(j=0; j 0; j--)
{
s = L_mult(exc[k], h[j]);
s = L_shl(s, h_fac); /* h is in Q(12-scaling) */
s_excf[j] = add(extract_h(s), s_excf[j-1]);
}
s_excf[0] = shr(exc[k], scaling);
}
}
return;
}
/*---------------------------------------------------------------------*
* Function G_pitch: *
* ~~~~~~~~ *
*---------------------------------------------------------------------*
* Compute correlations and to use in gains quantizer. *
* Also compute the gain of pitch. Result in Q14 *
* if (gain < 0) gain =0 *
* if (gain >1.2) gain =1.2 *
*---------------------------------------------------------------------*/
Word16 G_pitch( /* (o) Q14 : Gain of pitch lag saturated to 1.2 */
Word16 xn[], /* (i) : Pitch target. */
Word16 y1[], /* (i) : Filtered adaptive codebook. */
Word16 g_coeff[], /* (i) : Correlations need for gain quantization. */
Word16 L_subfr /* (i) : Length of subframe. */
)
{
Word16 i;
Word16 xy, yy, exp_xy, exp_yy, gain;
Word32 s;
Word16 scaled_y1[L_SUBFR];
/* divide "y1[]" by 4 to avoid overflow */
for(i=0; i */
Overflow = 0;
s = 1; /* Avoid case of all zeros */
for(i=0; i */
Overflow = 0;
s = 0;
for(i=0; i 1.99 in Q14 */
/* if(gain >1.2) gain = 1.2 in Q14 */
if( sub(gain, 19661) > 0)
{
gain = 19661;
}
return(gain);
}
/*----------------------------------------------------------------------*
* Function Enc_lag3 *
* ~~~~~~~~ *
* Encoding of fractional pitch lag with 1/3 resolution. *
*----------------------------------------------------------------------*
* The pitch range for the first subframe is divided as follows: *
* 19 1/3 to 84 2/3 resolution 1/3 *
* 85 to 143 resolution 1 *
* *
* The period in the first subframe is encoded with 8 bits. *
* For the range with fractions: *
* index = (T-19)*3 + frac - 1; where T=[19..85] and frac=[-1,0,1] *
* and for the integer only range *
* index = (T - 85) + 197; where T=[86..143] *
*----------------------------------------------------------------------*
* For the second subframe a resolution of 1/3 is always used, and the *
* search range is relative to the lag in the first subframe. *
* If t0 is the lag in the first subframe then *
* t_min=t0-5 and t_max=t0+4 and the range is given by *
* t_min - 2/3 to t_max + 2/3 *
* *
* The period in the 2nd subframe is encoded with 5 bits: *
* index = (T-(t_min-1))*3 + frac - 1; where T[t_min-1 .. t_max+1] *
*----------------------------------------------------------------------*/
Word16 Enc_lag3( /* output: Return index of encoding */
Word16 T0, /* input : Pitch delay */
Word16 T0_frac, /* input : Fractional pitch delay */
Word16 *T0_min, /* in/out: Minimum search delay */
Word16 *T0_max, /* in/out: Maximum search delay */
Word16 pit_min, /* input : Minimum pitch delay */
Word16 pit_max, /* input : Maximum pitch delay */
Word16 pit_flag /* input : Flag for 1st subframe */
)
{
Word16 index, i;
if (pit_flag == 0) /* if 1st subframe */
{
/* encode pitch delay (with fraction) */
if (sub(T0, 85) <= 0)
{
/* index = t0*3 - 58 + t0_frac */
i = add(add(T0, T0), T0);
index = add(sub(i, 58), T0_frac);
}
else {
index = add(T0, 112);
}
/* find T0_min and T0_max for second (or fourth) subframe */
*T0_min = sub(T0, 5);
if (sub(*T0_min, pit_min) < 0)
{
*T0_min = pit_min;
}
*T0_max = add(*T0_min, 9);
if (sub(*T0_max, pit_max) > 0)
{
*T0_max = pit_max;
*T0_min = sub(*T0_max, 9);
}
}
else /* if second subframe */
{
/* i = t0 - t0_min; */
/* index = i*3 + 2 + t0_frac; */
i = sub(T0, *T0_min);
i = add(add(i, i), i);
index = add(add(i, 2), T0_frac);
}
return index;
}
/*---------------------------------------------------------------------------*
* Procedure Interpol_3() *
* ~~~~~~~~~~~~~~~~~~~~~~ *
* For interpolating the normalized correlation with 1/3 resolution. *
*--------------------------------------------------------------------------*/
Word16 Interpol_3( /* (o) : interpolated value */
Word16 *x, /* (i) : input vector */
Word16 frac /* (i) : fraction */
)
{
Word16 i, k;
Word16 *x1, *x2, *c1, *c2;
Word32 s;
if(frac < 0)
{
frac = add(frac, UP_SAMP);
x--;
}
x1 = &x[0];
x2 = &x[1];
c1 = &inter_3[frac];
c2 = &inter_3[sub(UP_SAMP,frac)];
s = 0;
for(i=0, k=0; i< L_INTER4; i++, k+=UP_SAMP)
{
s = L_mac(s, x1[-i], c1[k]);
s = L_mac(s, x2[i], c2[k]);
}
return round(s);
}