FreeCalypso > hg > gsm-codec-lib
view libgsmefr/dtx.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 | 58b64224d4ac |
children |
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/*************************************************************************** * * File Name: dtx.c * * Purpose: Contains functions for performing DTX operation and comfort * noise generation. * * Below is a listing of all the functions appearing in the file. * The functions are arranged according to their purpose. Under * each heading, the ordering is hierarchical. * * Resetting of static variables of TX DTX: * reset_tx_dtx() * Resetting of static variables of RX DTX: * reset_rx_dtx() * * TX DTX handler (called by the speech encoder): * tx_dtx() * RX DTX handler (called by the speech decoder): * rx_dtx() * Encoding of comfort noise parameters into SID frame: * CN_encoding() * Encoding of SID codeword into SID frame: * sid_codeword_encoding() * Detecting of SID codeword from a frame: * sid_frame_detection() * Update the LSF parameter history: * update_lsf_history() * Update the reference LSF parameter vector: * update_lsf_p_CN() * Compute the averaged LSF parameter vector: * aver_lsf_history() * Update the fixed codebook gain parameter history of the encoder: * update_gain_code_history_tx() * Update the fixed codebook gain parameter history of the decoder: * update_gain_code_history_rx() * Compute the unquantized fixed codebook gain: * compute_CN_excitation_gain() * Update the reference fixed codebook gain: * update_gcode0_CN() * Compute the averaged fixed codebook gain: * aver_gain_code_history() * Compute the comfort noise fixed codebook excitation: * build_CN_code() * Generate a random integer value: * pseudonoise() * Interpolate a comfort noise parameter value over the comfort noise * update period: * interpolate_CN_param() * Interpolate comfort noise LSF pparameter values over the comfort * noise update period: * interpolate_CN_lsf() * interpolate_CN_param() * **************************************************************************/ #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 "enc_state.h" #include "dec_state.h" /* Inverse values of DTX hangover period and DTX hangover period + 1 */ #define INV_DTX_HANGOVER (0x7fff / DTX_HANGOVER) #define INV_DTX_HANGOVER_P1 (0x7fff / (DTX_HANGOVER+1)) #define NB_PULSE 10 /* Number of pulses in fixed codebook excitation */ /* Constant DTX_ELAPSED_THRESHOLD is used as threshold for allowing SID frame updating without hangover period in case when elapsed time measured from previous SID update is below 24 */ #define DTX_ELAPSED_THRESHOLD (24 + DTX_HANGOVER - 1) /************************************************************************* * * 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: reset_rx_dtx * * PURPOSE: Resets the static variables of the RX DTX handler to their * initial values * *************************************************************************/ void reset_rx_dtx (struct EFR_decoder_state *st) { Word16 i; /* suppose infinitely long speech period before start */ st->rxdtx_aver_period = DTX_HANGOVER; st->rxdtx_N_elapsed = 0x7fff; st->rxdtx_ctrl = RX_SP_FLAG; for (i = 0; i < DTX_HANGOVER; i++) { st->lsf_old_rx[i][0] = 1384; st->lsf_old_rx[i][1] = 2077; st->lsf_old_rx[i][2] = 3420; st->lsf_old_rx[i][3] = 5108; st->lsf_old_rx[i][4] = 6742; st->lsf_old_rx[i][5] = 8122; st->lsf_old_rx[i][6] = 9863; st->lsf_old_rx[i][7] = 11092; st->lsf_old_rx[i][8] = 12714; st->lsf_old_rx[i][9] = 13701; } for (i = 0; i < 4 * DTX_HANGOVER; i++) { st->gain_code_old_rx[i] = 0; } st->L_pn_seed_rx = PN_INITIAL_SEED; st->rx_dtx_state = CN_INT_PERIOD - 1; st->prev_SID_frames_lost = 0; st->buf_p_rx = 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 (sub (VAD_flag, 1) == 0) { 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 = sub (st->txdtx_hangover, 1); /* 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 (sub (add (st->txdtx_N_elapsed, st->txdtx_hangover), DTX_ELAPSED_THRESHOLD) < 0) { /* 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: rx_dtx * * PURPOSE: DTX handler of the speech decoder. Determines when to update * the reference comfort noise parameters (LSF and gain) at the * end of the speech burst. Also classifies the incoming frames * according to SID flag and BFI flag * and determines when the transmission is active during comfort * noise insertion. This function also initializes the pseudo * noise generator shift register. * * Operation of the RX DTX handler is based on measuring the * lengths of speech bursts and the lengths of the pauses between * speech bursts to determine when there exists a hangover period * at the end of a speech burst. The idea is to keep in sync with * the TX DTX handler to be able to update the reference comfort * noise parameters at the same time instances. * * INPUTS: *rxdtx_ctrl Old decoder DTX control word * TAF Time alignment flag * bfi Bad frame indicator flag * SID_flag Silence descriptor flag * * OUTPUTS: *rxdtx_ctrl Updated decoder DTX control word * rx_dtx_state Updated state of comfort noise interpolation * period (global variable) * L_pn_seed_rx Initialized pseudo noise generator shift * register (global variable) * * RETURN VALUE: none * *************************************************************************/ void rx_dtx ( struct EFR_decoder_state *st, Word16 TAF, Word16 bfi, Word16 SID_flag ) { Word16 frame_type; /* Frame classification according to bfi-flag and ternary-valued SID flag. The frames between SID updates (not actually trans- mitted) are also classified here; they will be discarded later and provided with "NO TRANSMISSION"-flag */ if ((sub (SID_flag, 2) == 0) && (bfi == 0)) { frame_type = VALID_SID_FRAME; move16 (); } else if ((SID_flag == 0) && (bfi == 0)) { frame_type = GOOD_SPEECH_FRAME; move16 (); } else if ((SID_flag == 0) && (bfi != 0)) { frame_type = UNUSABLE_FRAME; move16 (); } else { frame_type = INVALID_SID_FRAME; move16 (); } /* Update of decoder state */ /* Previous frame was classified as a speech frame */ if ((st->rxdtx_ctrl & RX_SP_FLAG) != 0) { if (sub (frame_type, VALID_SID_FRAME) == 0) { st->rxdtx_ctrl = RX_FIRST_SID_UPDATE; } else if (sub (frame_type, INVALID_SID_FRAME) == 0) { st->rxdtx_ctrl = RX_FIRST_SID_UPDATE | RX_INVALID_SID_FRAME; } else if (sub (frame_type, UNUSABLE_FRAME) == 0) { st->rxdtx_ctrl = RX_SP_FLAG; } else if (sub (frame_type, GOOD_SPEECH_FRAME) == 0) { st->rxdtx_ctrl = RX_SP_FLAG; } } else { if (sub (frame_type, VALID_SID_FRAME) == 0) { st->rxdtx_ctrl = RX_CONT_SID_UPDATE; } else if (sub (frame_type, INVALID_SID_FRAME) == 0) { st->rxdtx_ctrl = RX_CONT_SID_UPDATE | RX_INVALID_SID_FRAME; } else if (sub (frame_type, UNUSABLE_FRAME) == 0) { st->rxdtx_ctrl = RX_CNI_BFI; } else if (sub (frame_type, GOOD_SPEECH_FRAME) == 0) { /* If the previous frame (during CNI period) was muted, raise the RX_PREV_DTX_MUTING flag */ if ((st->rxdtx_ctrl & RX_DTX_MUTING) != 0) { st->rxdtx_ctrl = RX_SP_FLAG | RX_FIRST_SP_FLAG | RX_PREV_DTX_MUTING; } else { st->rxdtx_ctrl = RX_SP_FLAG | RX_FIRST_SP_FLAG; } } } if ((st->rxdtx_ctrl & RX_SP_FLAG) != 0) { st->prev_SID_frames_lost = 0; st->rx_dtx_state = CN_INT_PERIOD - 1; } else { /* First SID frame */ if ((st->rxdtx_ctrl & RX_FIRST_SID_UPDATE) != 0) { st->prev_SID_frames_lost = 0; st->rx_dtx_state = CN_INT_PERIOD - 1; } /* SID frame detected, but not the first SID */ if ((st->rxdtx_ctrl & RX_CONT_SID_UPDATE) != 0) { st->prev_SID_frames_lost = 0; if (sub (frame_type, VALID_SID_FRAME) == 0) { st->rx_dtx_state = 0; } else if (sub (frame_type, INVALID_SID_FRAME) == 0) { if (sub(st->rx_dtx_state, (CN_INT_PERIOD - 1)) < 0) { st->rx_dtx_state = add(st->rx_dtx_state, 1); } } } /* Bad frame received in CNI mode */ if ((st->rxdtx_ctrl & RX_CNI_BFI) != 0) { if (sub (st->rx_dtx_state, (CN_INT_PERIOD - 1)) < 0) { st->rx_dtx_state = add (st->rx_dtx_state, 1); } /* If an unusable frame is received during CNI period when TAF == 1, the frame is classified as a lost SID frame */ if (sub (TAF, 1) == 0) { st->rxdtx_ctrl = st->rxdtx_ctrl | RX_LOST_SID_FRAME; st->prev_SID_frames_lost = add (st->prev_SID_frames_lost, 1); } else /* No transmission occurred */ { st->rxdtx_ctrl = st->rxdtx_ctrl | RX_NO_TRANSMISSION; } if (sub (st->prev_SID_frames_lost, 1) > 0) { st->rxdtx_ctrl = st->rxdtx_ctrl | RX_DTX_MUTING; } } } /* N_elapsed (frames since last SID update) is incremented. If SID is updated N_elapsed is cleared later in this function */ st->rxdtx_N_elapsed = add (st->rxdtx_N_elapsed, 1); if ((st->rxdtx_ctrl & RX_SP_FLAG) != 0) { st->rxdtx_aver_period = DTX_HANGOVER; } else { if (sub (st->rxdtx_N_elapsed, DTX_ELAPSED_THRESHOLD) > 0) { st->rxdtx_ctrl |= RX_UPD_SID_QUANT_MEM; st->rxdtx_N_elapsed = 0; st->rxdtx_aver_period = 0; st->L_pn_seed_rx = PN_INITIAL_SEED; } else if (st->rxdtx_aver_period == 0) { st->rxdtx_N_elapsed = 0; } else { st->rxdtx_aver_period = sub (st->rxdtx_aver_period, 1); } } 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: update_lsf_history * * PURPOSE: Update the LSF parameter history. The LSF parameters kept * in the buffer are used later for computing the reference * LSF parameter vector and the averaged LSF parameter vector. * * INPUTS: lsf1[0..9] LSF vector of the 1st half of the frame * lsf2[0..9] LSF vector of the 2nd half of the frame * lsf_old[0..DTX_HANGOVER-1][0..M-1] * Old LSF history * * OUTPUTS: lsf_old[0..DTX_HANGOVER-1][0..M-1] * Updated LSF history * * RETURN VALUE: none * *************************************************************************/ void update_lsf_history ( Word16 lsf1[M], Word16 lsf2[M], Word16 lsf_old[DTX_HANGOVER][M] ) { Word16 i, j, temp; /* shift LSF data to make room for LSFs from current frame */ /* This can also be implemented by using circular buffering */ for (i = DTX_HANGOVER - 1; i > 0; i--) { for (j = 0; j < M; j++) { lsf_old[i][j] = lsf_old[i - 1][j]; move16 (); } } /* Store new LSF data to lsf_old buffer */ for (i = 0; i < M; i++) { temp = add (shr (lsf1[i], 1), shr (lsf2[i], 1)); lsf_old[0][i] = temp; move16 (); } return; } /************************************************************************* * * FUNCTION NAME: update_lsf_p_CN * * PURPOSE: Update the reference LSF parameter vector. The reference * vector is computed by averaging the quantized LSF parameter * vectors which exist in the LSF parameter history. * * INPUTS: lsf_old[0..DTX_HANGOVER-1][0..M-1] * LSF parameter history * * OUTPUTS: lsf_p_CN[0..9] Computed reference LSF parameter vector * * RETURN VALUE: none * *************************************************************************/ void update_lsf_p_CN ( Word16 lsf_old[DTX_HANGOVER][M], Word16 lsf_p_CN[M] ) { Word16 i, j; Word32 L_temp; for (j = 0; j < M; j++) { L_temp = L_mult (INV_DTX_HANGOVER, lsf_old[0][j]); for (i = 1; i < DTX_HANGOVER; i++) { L_temp = L_mac (L_temp, INV_DTX_HANGOVER, lsf_old[i][j]); } lsf_p_CN[j] = round (L_temp); move16 (); } 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 (sub (st->buf_p_tx, (4 * DTX_HANGOVER - 1)) == 0) { st->buf_p_tx = 0; } else { st->buf_p_tx = add (st->buf_p_tx, 1); } return; } /************************************************************************* * * FUNCTION NAME: update_gain_code_history_rx * * PURPOSE: Update the fixed codebook gain parameter history of the * decoder. The fixed codebook gain parameters kept in the buffer * are used later for computing the reference 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 decoder * * OUTPUTS: gain_code_old_tx[0..4*DTX_HANGOVER-1] * Updated fixed codebk gain history of decoder * * RETURN VALUE: none * *************************************************************************/ void update_gain_code_history_rx ( struct EFR_decoder_state *st, Word16 new_gain_code ) { /* Circular buffer */ st->gain_code_old_rx[st->buf_p_rx] = new_gain_code; if (sub (st->buf_p_rx, (4 * DTX_HANGOVER - 1)) == 0) { st->buf_p_rx = 0; } else { st->buf_p_rx = add (st->buf_p_rx, 1); } 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_sub (L_temp, MAX_32) == 0) { 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: update_gcode0_CN * * PURPOSE: Update the reference fixed codebook gain parameter value. * The reference value is computed by averaging the quantized * fixed codebook gain parameter values which exist in the * fixed codebook gain parameter history. * * INPUTS: gain_code_old[0..4*DTX_HANGOVER-1] * fixed codebook gain parameter history * * OUTPUTS: none * * RETURN VALUE: Computed reference fixed codebook gain * *************************************************************************/ Word16 update_gcode0_CN ( Word16 gain_code_old[4 * DTX_HANGOVER] ) { Word16 i, j; Word32 L_temp, L_ret; L_ret = 0L; move32 (); for (i = 0; i < DTX_HANGOVER; i++) { L_temp = L_mult (0x1fff, gain_code_old[4 * i]); for (j = 1; j < 4; j++) { L_temp = L_mac (L_temp, 0x1fff, gain_code_old[4 * i + j]); } L_ret = L_mac (L_ret, INV_DTX_HANGOVER, extract_h (L_temp)); } return extract_h (L_ret); } /************************************************************************* * * 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); } /************************************************************************* * * FUNCTION NAME: build_CN_code * * PURPOSE: Compute the comfort noise fixed codebook excitation. The * gains of the pulses are always +/-1. * * INPUTS: *seed Old CN generator shift register state * * OUTPUTS: cod[0..39] Generated comfort noise fixed codebook vector * *seed Updated CN generator shift register state * * RETURN VALUE: none * *************************************************************************/ void build_CN_code ( Word16 cod[], Word32 *seed ) { Word16 i, j, k; for (i = 0; i < L_SUBFR; i++) { cod[i] = 0; move16 (); } for (k = 0; k < NB_PULSE; k++) { i = pseudonoise (seed, 2); /* generate pulse position */ i = shr (extract_l (L_mult (i, 10)), 1); i = add (i, k); j = pseudonoise (seed, 1); /* generate sign */ test (); if (j > 0) { cod[i] = 4096; move16 (); } else { cod[i] = -4096; move16 (); } } return; } /************************************************************************* * * FUNCTION NAME: pseudonoise * * PURPOSE: Generate a random integer value to use in comfort noise * generation. The algorithm uses polynomial x^31 + x^3 + 1 * (length of PN sequence is 2^31 - 1). * * INPUTS: *shift_reg Old CN generator shift register state * * * OUTPUTS: *shift_reg Updated CN generator shift register state * * RETURN VALUE: Generated random integer value * *************************************************************************/ Word16 pseudonoise ( Word32 *shift_reg, Word16 no_bits ) { Word16 noise_bits, Sn, i; noise_bits = 0; move16 (); for (i = 0; i < no_bits; i++) { /* State n == 31 */ test (); logic32 (); if ((*shift_reg & 0x00000001L) != 0) { Sn = 1; move16 (); } else { Sn = 0; move16 (); } /* State n == 3 */ test (); logic32 (); if ((*shift_reg & 0x10000000L) != 0) { Sn = Sn ^ 1; logic16 (); } else { Sn = Sn ^ 0; logic16 (); } noise_bits = shl (noise_bits, 1); noise_bits = noise_bits | (extract_l (*shift_reg) & 1); logic16 (); logic16 (); *shift_reg = L_shr (*shift_reg, 1); move32 (); test (); logic16 (); if (Sn & 1) { *shift_reg = *shift_reg | 0x40000000L; move32 (); logic32 (); } } return noise_bits; } /************************************************************************* * * FUNCTION NAME: interpolate_CN_param * * PURPOSE: Interpolate a comfort noise parameter value over the comfort * noise update period. * * INPUTS: old_param The older parameter of the interpolation * (the endpoint the interpolation is started * from) * new_param The newer parameter of the interpolation * (the endpoint the interpolation is ended to) * rx_dtx_state State of the comfort noise insertion period * * OUTPUTS: none * * RETURN VALUE: Interpolated CN parameter value * *************************************************************************/ Word16 interpolate_CN_param ( Word16 old_param, Word16 new_param, Word16 rx_dtx_state ) { static const Word16 interp_factor[CN_INT_PERIOD] = { 0x0555, 0x0aaa, 0x1000, 0x1555, 0x1aaa, 0x2000, 0x2555, 0x2aaa, 0x3000, 0x3555, 0x3aaa, 0x4000, 0x4555, 0x4aaa, 0x5000, 0x5555, 0x5aaa, 0x6000, 0x6555, 0x6aaa, 0x7000, 0x7555, 0x7aaa, 0x7fff}; Word16 temp; Word32 L_temp; L_temp = L_mult (interp_factor[rx_dtx_state], new_param); temp = sub (0x7fff, interp_factor[rx_dtx_state]); temp = add (temp, 1); L_temp = L_mac (L_temp, temp, old_param); temp = round (L_temp); return temp; } /************************************************************************* * * FUNCTION NAME: interpolate_CN_lsf * * PURPOSE: Interpolate comfort noise LSF parameter vector over the comfort * noise update period. * * INPUTS: lsf_old_CN[0..9] * The older LSF parameter vector of the * interpolation (the endpoint the interpolation * is started from) * lsf_new_CN[0..9] * The newer LSF parameter vector of the * interpolation (the endpoint the interpolation * is ended to) * rx_dtx_state State of the comfort noise insertion period * * OUTPUTS: lsf_interp_CN[0..9] * Interpolated LSF parameter vector * * RETURN VALUE: none * *************************************************************************/ void interpolate_CN_lsf ( Word16 lsf_old_CN[M], Word16 lsf_new_CN[M], Word16 lsf_interp_CN[M], Word16 rx_dtx_state ) { Word16 i; for (i = 0; i < M; i++) { lsf_interp_CN[i] = interpolate_CN_param (lsf_old_CN[i], lsf_new_CN[i], rx_dtx_state); move16 (); } return; }