FreeCalypso > hg > gsm-codec-lib
view libgsmefr/pitch_f6.c @ 110:913fe3c11890
libgsmefr/vad.c: initial import from ETSI code
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Tue, 29 Nov 2022 03:01:38 +0000 |
parents | e0e53bfe1a8a |
children | d714168fb6dc |
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/************************************************************************* * * FUNCTION: Pitch_fr6() * * PURPOSE: Find the pitch period with 1/6 subsample resolution (closed loop). * * DESCRIPTION: * - find the normalized correlation between the target and filtered * past excitation in the search range. * - select the delay with maximum normalized correlation. * - interpolate the normalized correlation at fractions -3/6 to 3/6 * with step 1/6 around the chosen delay. * - The fraction which gives the maximum interpolated value is chosen. * *************************************************************************/ #include "gsm_efr.h" #include "typedef.h" #include "namespace.h" #include "basic_op.h" #include "oper_32b.h" #include "no_count.h" #include "sig_proc.h" #include "codec.h" /* L_inter = Length for fractional interpolation = nb.coeff/2 */ #define L_inter 4 /* Local functions */ static void Norm_Corr (Word16 exc[], Word16 xn[], Word16 h[], Word16 L_subfr, Word16 t_min, Word16 t_max, Word16 corr_norm[]); Word16 Pitch_fr6 ( /* (o) : pitch period. */ Word16 exc[], /* (i) : excitation buffer */ Word16 xn[], /* (i) : target vector */ Word16 h[], /* (i) : impulse response of synthesis and weighting filters */ Word16 L_subfr, /* (i) : Length of subframe */ Word16 t0_min, /* (i) : minimum value in the searched range. */ Word16 t0_max, /* (i) : maximum value in the searched range. */ Word16 i_subfr, /* (i) : indicator for first subframe. */ Word16 *pit_frac /* (o) : chosen fraction. */ ) { Word16 i; Word16 t_min, t_max; Word16 max, lag, frac; Word16 *corr; Word16 corr_int; Word16 corr_v[40]; /* Total length = t0_max-t0_min+1+2*L_inter */ /* Find interval to compute normalized correlation */ t_min = sub (t0_min, L_inter); t_max = add (t0_max, L_inter); corr = &corr_v[-t_min]; move16 (); /* Compute normalized correlation between target and filtered excitation */ Norm_Corr (exc, xn, h, L_subfr, t_min, t_max, corr); /* Find integer pitch */ max = corr[t0_min]; move16 (); lag = t0_min; move16 (); for (i = t0_min + 1; i <= t0_max; i++) { test (); if (sub (corr[i], max) >= 0) { max = corr[i]; move16 (); lag = i; move16 (); } } /* If first subframe and lag > 94 do not search fractional pitch */ test (); test (); if ((i_subfr == 0) && (sub (lag, 94) > 0)) { *pit_frac = 0; move16 (); return (lag); } /* Test the fractions around T0 and choose the one which maximizes */ /* the interpolated normalized correlation. */ max = Interpol_6 (&corr[lag], -3); frac = -3; move16 (); for (i = -2; i <= 3; i++) { corr_int = Interpol_6 (&corr[lag], i); move16 (); test (); if (sub (corr_int, max) > 0) { max = corr_int; move16 (); frac = i; move16 (); } } /* Limit the fraction value in the interval [-2,-1,0,1,2,3] */ test (); if (sub (frac, -3) == 0) { frac = 3; move16 (); lag = sub (lag, 1); } *pit_frac = frac; move16 (); return (lag); } /************************************************************************* * * FUNCTION: Norm_Corr() * * PURPOSE: Find the normalized correlation between the target vector * and the filtered past excitation. * * DESCRIPTION: * The normalized correlation is given by the correlation between the * target and filtered past excitation divided by the square root of * the energy of filtered excitation. * corr[k] = <x[], y_k[]>/sqrt(y_k[],y_k[]) * where x[] is the target vector and y_k[] is the filtered past * excitation at delay k. * *************************************************************************/ 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; /* Usally dynamic allocation of (L_subfr) */ Word16 excf[80]; Word16 scaling, h_fac, *s_excf, scaled_excf[80]; k = -t_min; move16 (); /* compute the filtered excitation for the first delay t_min */ Convolve (&exc[k], h, excf, L_subfr); /* scale "excf[]" to avoid overflow */ for (j = 0; j < L_subfr; j++) { scaled_excf[j] = shr (excf[j], 2); move16 (); } /* Compute 1/sqrt(energy of excf[]) */ s = 0; move32 (); for (j = 0; j < L_subfr; j++) { s = L_mac (s, excf[j], excf[j]); } test (); if (L_sub (s, 67108864L) <= 0) /* if (s <= 2^26) */ { s_excf = excf; move16 (); h_fac = 15 - 12; move16 (); scaling = 0; move16 (); } else { /* "excf[]" is divided by 2 */ s_excf = scaled_excf; move16 (); h_fac = 15 - 12 - 2; move16 (); scaling = 2; move16 (); } /* loop for every possible period */ for (i = t_min; i <= t_max; i++) { /* Compute 1/sqrt(energy of excf[]) */ s = 0; move32 (); for (j = 0; j < L_subfr; j++) { s = L_mac (s, s_excf[j], s_excf[j]); } s = Inv_sqrt (s); move16 (); L_Extract (s, &norm_h, &norm_l); /* Compute correlation between xn[] and excf[] */ s = 0; move32 (); for (j = 0; j < L_subfr; j++) { s = L_mac (s, xn[j], s_excf[j]); } L_Extract (s, &corr_h, &corr_l); /* Normalize correlation = correlation * (1/sqrt(energy)) */ s = Mpy_32 (corr_h, corr_l, norm_h, norm_l); corr_norm[i] = extract_h (L_shl (s, 16)); move16 (); /* modify the filtered excitation excf[] for the next iteration */ test (); if (sub (i, t_max) != 0) { k--; for (j = L_subfr - 1; j > 0; j--) { s = L_mult (exc[k], h[j]); s = L_shl (s, h_fac); s_excf[j] = add (extract_h (s), s_excf[j - 1]); move16 (); } s_excf[0] = shr (exc[k], scaling); move16 (); } } return; }