FreeCalypso > hg > gsm-codec-lib
view libgsmefr/pitch_ol.c @ 489:f036e1de5b05
libgsmhr1: starting with API definition
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Sat, 15 Jun 2024 04:51:30 +0000 |
parents | b4531e7227ca |
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/************************************************************************* * * FUNCTION: Pitch_ol * * PURPOSE: Compute the open loop pitch lag. * * DESCRIPTION: * The open-loop pitch lag is determined based on the perceptually * weighted speech signal. This is done in the following steps: * - find three maxima of the correlation <sw[n],sw[n-T]> in the * follwing three ranges of T : [18,35], [36,71], and [72, 143] * - divide each maximum by <sw[n-t], sw[n-t]> where t is the delay at * that maximum correlation. * - select the delay of maximum normalized correlation (among the * three candidates) while favoring the lower delay ranges. * *************************************************************************/ #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" #define THRESHOLD 27853 /* local function */ static Word16 Lag_max ( /* output: lag found */ Word16 scal_sig[], /* input : scaled signal */ Word16 scal_fac, /* input : scaled signal factor */ 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; /* Scaled signal */ /* Can be allocated with memory allocation of(pit_max+L_frame) */ Word16 scaled_signal[512]; Word16 *scal_sig, scal_fac; scal_sig = &scaled_signal[pit_max]; move16 (); t0 = 0L; move32 (); 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]>>2 * * else if t0 < 1^22 -> scal_sig[i] = signal[i]<<2 * * else -> scal_sig[i] = signal[i] * *--------------------------------------------------------*/ /*--------------------------------------------------------* * Verification for risk of overflow. * *--------------------------------------------------------*/ test (); test (); if (t0 == MAX_32) /* Test for overflow */ { for (i = -pit_max; i < L_frame; i++) { scal_sig[i] = shr (signal[i], 3); move16 (); } scal_fac = 3; move16 (); } else if (t0 < (Word32) 1048576L) /* if (t0 < 2^20) */ { for (i = -pit_max; i < L_frame; i++) { scal_sig[i] = shl (signal[i], 3); move16 (); } scal_fac = -3; move16 (); } else { for (i = -pit_max; i < L_frame; i++) { scal_sig[i] = signal[i]; move16 (); } scal_fac = 0; move16 (); } /*--------------------------------------------------------------------* * The pitch lag search is divided in three sections. * * Each section cannot have a pitch multiple. * * We find a maximum for each section. * * We compare the maximum of each section by favoring small lags. * * * * First section: lag delay = pit_max downto 4*pit_min * * Second section: lag delay = 4*pit_min-1 downto 2*pit_min * * Third section: lag delay = 2*pit_min-1 downto pit_min * *-------------------------------------------------------------------*/ j = shl (pit_min, 2); p_max1 = Lag_max (scal_sig, scal_fac, L_frame, pit_max, j, &max1); i = sub (j, 1); j = shl (pit_min, 1); p_max2 = Lag_max (scal_sig, scal_fac, L_frame, i, j, &max2); i = sub (j, 1); p_max3 = Lag_max (scal_sig, scal_fac, L_frame, i, pit_min, &max3); /*--------------------------------------------------------------------* * Compare the 3 sections maximum, and favor small lag. * *-------------------------------------------------------------------*/ test (); if (mult (max1, THRESHOLD) < max2) { max1 = max2; move16 (); p_max1 = p_max2; move16 (); } test (); if (mult (max1, THRESHOLD) < max3) { p_max1 = p_max3; move16 (); } return (p_max1); } /************************************************************************* * * FUNCTION: Lag_max * * PURPOSE: Find the lag that has maximum correlation of scal_sig[] in a * given delay range. * * DESCRIPTION: * The correlation is given by * cor[t] = <scal_sig[n],scal_sig[n-t]>, t=lag_min,...,lag_max * The functions outputs the maximum correlation after normalization * and the corresponding lag. * *************************************************************************/ static Word16 Lag_max ( /* output: lag found */ Word16 scal_sig[], /* input : scaled signal. */ Word16 scal_fac, /* input : scaled signal factor. */ 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 i, j; Word16 *p, *p1; Word32 max, t0; Word16 max_h, max_l, ener_h, ener_l; Word16 p_max; max = MIN_32; move32 (); for (i = lag_max; i >= lag_min; i--) { p = scal_sig; move16 (); p1 = &scal_sig[-i]; move16 (); t0 = 0; move32 (); for (j = 0; j < L_frame; j++, p++, p1++) { t0 = L_mac (t0, *p, *p1); } test (); if (t0 >= max) { max = t0; move32 (); p_max = i; move16 (); } } /* compute energy */ t0 = 0; move32 (); p = &scal_sig[-p_max]; move16 (); for (i = 0; i < L_frame; i++, p++) { t0 = L_mac (t0, *p, *p); } /* 1/sqrt(energy) */ t0 = Inv_sqrt (t0); t0 = L_shl (t0, 1); /* max = max/sqrt(energy) */ L_Extract (max, &max_h, &max_l); L_Extract (t0, &ener_h, &ener_l); t0 = Mpy_32 (max_h, max_l, ener_h, ener_l); t0 = L_shr (t0, scal_fac); *cor_max = extract_h (L_shl (t0, 15)); move16 (); /* divide by 2 */ return (p_max); }