FreeCalypso > hg > gsm-codec-lib
view libgsmefr/dtx_enc.c @ 254:f931e704adc5
libtwamr: bits and parameter packing
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Fri, 05 Apr 2024 07:41:31 +0000 |
parents | cf39a90f5196 |
children |
line wrap: on
line source
/* * This file is a product of splitting ETSI EFR dtx.c into parts; * the present module is the encoder-specific part. */ #include "gsm_efr.h" #include "typedef.h" #include "namespace.h" #include "basic_op.h" #include "cnst.h" #include "sig_proc.h" #include "memops.h" #include "no_count.h" #include "dtx.h" #include "dtx_defs.h" #include "enc_state.h" /************************************************************************* * * FUNCTION NAME: reset_tx_dtx * * PURPOSE: Resets the static variables of the TX DTX handler to their * initial values * *************************************************************************/ void reset_tx_dtx (struct EFR_encoder_state *st) { Word16 i; /* suppose infinitely long speech period before start */ st->txdtx_hangover = DTX_HANGOVER; st->txdtx_N_elapsed = 0x7fff; st->txdtx_ctrl = TX_SP_FLAG | TX_VAD_FLAG; for (i = 0; i < 6; i++) { st->old_CN_mem_tx[i] = 0; } for (i = 0; i < DTX_HANGOVER; i++) { st->lsf_old_tx[i][0] = 1384; st->lsf_old_tx[i][1] = 2077; st->lsf_old_tx[i][2] = 3420; st->lsf_old_tx[i][3] = 5108; st->lsf_old_tx[i][4] = 6742; st->lsf_old_tx[i][5] = 8122; st->lsf_old_tx[i][6] = 9863; st->lsf_old_tx[i][7] = 11092; st->lsf_old_tx[i][8] = 12714; st->lsf_old_tx[i][9] = 13701; } for (i = 0; i < 4 * DTX_HANGOVER; i++) { st->gain_code_old_tx[i] = 0; } st->L_pn_seed_tx = PN_INITIAL_SEED; st->buf_p_tx = 0; return; } /************************************************************************* * * FUNCTION NAME: tx_dtx * * PURPOSE: DTX handler of the speech encoder. Determines when to add * the hangover period to the end of the speech burst, and * also determines when to use old SID parameters, and when * to update the SID parameters. This function also initializes * the pseudo noise generator shift register. * * Operation of the TX DTX handler is based on the VAD flag * given as input from the speech encoder. * * INPUTS: VAD_flag Voice activity decision * *txdtx_ctrl Old encoder DTX control word * * OUTPUTS: *txdtx_ctrl Updated encoder DTX control word * L_pn_seed_tx Initialized pseudo noise generator shift * register (global variable) * * RETURN VALUE: none * *************************************************************************/ void tx_dtx ( struct EFR_encoder_state *st, Word16 VAD_flag ) { /* N_elapsed (frames since last SID update) is incremented. If SID is updated N_elapsed is cleared later in this function */ st->txdtx_N_elapsed = add (st->txdtx_N_elapsed, 1); /* If voice activity was detected, reset hangover counter */ if (VAD_flag == 1) { st->txdtx_hangover = DTX_HANGOVER; st->txdtx_ctrl = TX_SP_FLAG | TX_VAD_FLAG; } else { if (st->txdtx_hangover == 0) { /* Hangover period is over, SID should be updated */ st->txdtx_N_elapsed = 0; /* Check if this is the first frame after hangover period */ if ((st->txdtx_ctrl & TX_HANGOVER_ACTIVE) != 0) { st->txdtx_ctrl = TX_PREV_HANGOVER_ACTIVE | TX_SID_UPDATE; st->L_pn_seed_tx = PN_INITIAL_SEED; } else { st->txdtx_ctrl = TX_SID_UPDATE; } } else { /* Hangover period is not over, update hangover counter */ st->txdtx_hangover--; /* Check if elapsed time from last SID update is greater than threshold. If not, set SP=0 (although hangover period is not over) and use old SID parameters for new SID frame. N_elapsed counter must be summed with hangover counter in order to avoid erroneus SP=1 decision in case when N_elapsed is grown bigger than threshold and hangover period is still active */ if (add (st->txdtx_N_elapsed, st->txdtx_hangover) < DTX_ELAPSED_THRESHOLD) { /* old SID frame should be used */ st->txdtx_ctrl = TX_USE_OLD_SID; } else { if ((st->txdtx_ctrl & TX_HANGOVER_ACTIVE) != 0) { st->txdtx_ctrl = TX_PREV_HANGOVER_ACTIVE | TX_HANGOVER_ACTIVE | TX_SP_FLAG; } else { st->txdtx_ctrl = TX_HANGOVER_ACTIVE | TX_SP_FLAG; } } } } return; } /************************************************************************* * * FUNCTION NAME: CN_encoding * * PURPOSE: Encoding of the comfort noise parameters into a SID frame. * Use old SID parameters if necessary. Set the parameter * indices not used by comfort noise parameters to zero. * * INPUTS: params[0..56] Comfort noise parameter frame from the * speech encoder * txdtx_ctrl TX DTX handler control word * * OUTPUTS: params[0..56] Comfort noise encoded parameter frame * * RETURN VALUE: none * *************************************************************************/ void CN_encoding ( struct EFR_encoder_state *st, Word16 params[], Word16 txdtx_ctrl ) { Word16 i; if ((txdtx_ctrl & TX_SID_UPDATE) != 0) { /* Store new CN parameters in memory to be used later as old CN parameters */ /* LPC parameter indices */ for (i = 0; i < 5; i++) { st->old_CN_mem_tx[i] = params[i]; } /* Codebook index computed in last subframe */ st->old_CN_mem_tx[5] = params[56]; } if ((txdtx_ctrl & TX_USE_OLD_SID) != 0) { /* Use old CN parameters previously stored in memory */ for (i = 0; i < 5; i++) { params[i] = st->old_CN_mem_tx[i]; } params[17] = st->old_CN_mem_tx[5]; params[30] = st->old_CN_mem_tx[5]; params[43] = st->old_CN_mem_tx[5]; params[56] = st->old_CN_mem_tx[5]; } /* Set all the rest of the parameters to zero (SID codeword will be written later) */ for (i = 0; i < 12; i++) { params[i + 5] = 0; params[i + 18] = 0; params[i + 31] = 0; params[i + 44] = 0; } return; } /************************************************************************* * * FUNCTION NAME: aver_lsf_history * * PURPOSE: Compute the averaged LSF parameter vector. Computation is * performed by averaging the LSF parameter vectors which exist * in the LSF parameter history, together with the LSF * parameter vectors of the current frame. * * INPUTS: lsf_old[0..DTX_HANGOVER-1][0..M-1] * LSF parameter history * lsf1[0..M-1] LSF vector of the 1st half of the frame * lsf2[0..M-1] LSF vector of the 2nd half of the frame * * OUTPUTS: lsf_aver[0..M-1] Averaged LSF parameter vector * * RETURN VALUE: none * *************************************************************************/ void aver_lsf_history ( Word16 lsf_old[DTX_HANGOVER][M], Word16 lsf1[M], Word16 lsf2[M], Word16 lsf_aver[M] ) { Word16 i, j; Word32 L_temp; for (j = 0; j < M; j++) { L_temp = L_mult (0x3fff, lsf1[j]); L_temp = L_mac (L_temp, 0x3fff, lsf2[j]); L_temp = L_mult (INV_DTX_HANGOVER_P1, extract_h (L_temp)); for (i = 0; i < DTX_HANGOVER; i++) { L_temp = L_mac (L_temp, INV_DTX_HANGOVER_P1, lsf_old[i][j]); } lsf_aver[j] = extract_h (L_temp); move16 (); } return; } /************************************************************************* * * FUNCTION NAME: update_gain_code_history_tx * * PURPOSE: Update the fixed codebook gain parameter history of the * encoder. The fixed codebook gain parameters kept in the buffer * are used later for computing the reference fixed codebook * gain parameter value and the averaged fixed codebook gain * parameter value. * * INPUTS: new_gain_code New fixed codebook gain value * * gain_code_old_tx[0..4*DTX_HANGOVER-1] * Old fixed codebook gain history of encoder * * OUTPUTS: gain_code_old_tx[0..4*DTX_HANGOVER-1] * Updated fixed codebook gain history of encoder * * RETURN VALUE: none * *************************************************************************/ void update_gain_code_history_tx ( struct EFR_encoder_state *st, Word16 new_gain_code ) { /* Circular buffer */ st->gain_code_old_tx[st->buf_p_tx] = new_gain_code; if (st->buf_p_tx == (4 * DTX_HANGOVER - 1)) { st->buf_p_tx = 0; } else { st->buf_p_tx++; } return; } /************************************************************************* * * FUNCTION NAME: compute_CN_excitation_gain * * PURPOSE: Compute the unquantized fixed codebook gain. Computation is * based on the energy of the Linear Prediction residual signal. * * INPUTS: res2[0..39] Linear Prediction residual signal * * OUTPUTS: none * * RETURN VALUE: Unquantized fixed codebook gain * *************************************************************************/ Word16 compute_CN_excitation_gain ( Word16 res2[L_SUBFR] ) { Word16 i, norm, norm1, temp, overfl; Word32 L_temp; /* Compute the energy of the LP residual signal */ norm = 0; move16 (); do { overfl = 0; move16 (); L_temp = 0L; move32 (); for (i = 0; i < L_SUBFR; i++) { temp = shr (res2[i], norm); L_temp = L_mac (L_temp, temp, temp); } test (); if (L_temp == MAX_32) { norm = add (norm, 1); overfl = 1; move16 (); /* Set the overflow flag */ } test (); } while (overfl != 0); L_temp = L_add (L_temp, 1L); /* Avoid the case of all zeros */ /* Take the square root of the obtained energy value (sqroot is a 2nd order Taylor series approximation) */ norm1 = norm_l (L_temp); temp = extract_h (L_shl (L_temp, norm1)); L_temp = L_mult (temp, temp); L_temp = L_sub (805306368L, L_shr (L_temp, 3)); L_temp = L_add (L_temp, L_mult (24576, temp)); temp = extract_h (L_temp); test (); logic16 (); if ((norm1 & 0x0001) != 0) { temp = mult_r (temp, 23170); norm1 = sub (norm1, 1); } /* Divide the result of sqroot operation by sqroot(10) */ temp = mult_r (temp, 10362); /* Re-scale to get the final value */ norm1 = shr (norm1, 1); norm1 = sub (norm1, norm); test (); if (norm1 >= 0) { temp = shr (temp, norm1); } else { temp = shl (temp, abs_s (norm1)); } return temp; } /************************************************************************* * * FUNCTION NAME: aver_gain_code_history * * PURPOSE: Compute the averaged fixed codebook gain parameter value. * Computation is performed by averaging the fixed codebook * gain parameter values which exist in the fixed codebook * gain parameter history, together with the fixed codebook * gain parameter value of the current subframe. * * INPUTS: CN_excitation_gain * Unquantized fixed codebook gain value * of the current subframe * gain_code_old[0..4*DTX_HANGOVER-1] * fixed codebook gain parameter history * * OUTPUTS: none * * RETURN VALUE: Averaged fixed codebook gain value * *************************************************************************/ Word16 aver_gain_code_history ( Word16 CN_excitation_gain, Word16 gain_code_old[4 * DTX_HANGOVER] ) { Word16 i; Word32 L_ret; L_ret = L_mult (0x470, CN_excitation_gain); for (i = 0; i < (4 * DTX_HANGOVER); i++) { L_ret = L_mac (L_ret, 0x470, gain_code_old[i]); } return extract_h (L_ret); }