ref: c77b96333b471c7b8a89852ee941e6a8987751b4
dir: /silk/SKP_Silk_CNG.c/
/***********************************************************************
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***********************************************************************/
#include "SKP_Silk_main.h"
/* Generates excitation for CNG LPC synthesis */
SKP_INLINE void SKP_Silk_CNG_exc(
SKP_int16 residual[], /* O CNG residual signal Q0 */
SKP_int32 exc_buf_Q10[], /* I Random samples buffer Q10 */
SKP_int32 Gain_Q16, /* I Gain to apply */
SKP_int length, /* I Length */
SKP_int32 *rand_seed /* I/O Seed to random index generator */
)
{
SKP_int32 seed;
SKP_int i, idx, exc_mask;
exc_mask = CNG_BUF_MASK_MAX;
while( exc_mask > length ) {
exc_mask = SKP_RSHIFT( exc_mask, 1 );
}
seed = *rand_seed;
for( i = 0; i < length; i++ ) {
seed = SKP_RAND( seed );
idx = ( SKP_int )( SKP_RSHIFT( seed, 24 ) & exc_mask );
SKP_assert( idx >= 0 );
SKP_assert( idx <= CNG_BUF_MASK_MAX );
residual[ i ] = ( SKP_int16 )SKP_SAT16( SKP_RSHIFT_ROUND( SKP_SMULWW( exc_buf_Q10[ idx ], Gain_Q16 ), 10 ) );
}
*rand_seed = seed;
}
void SKP_Silk_CNG_Reset(
SKP_Silk_decoder_state *psDec /* I/O Decoder state */
)
{
SKP_int i, NLSF_step_Q15, NLSF_acc_Q15;
NLSF_step_Q15 = SKP_DIV32_16( SKP_int16_MAX, psDec->LPC_order + 1 );
NLSF_acc_Q15 = 0;
for( i = 0; i < psDec->LPC_order; i++ ) {
NLSF_acc_Q15 += NLSF_step_Q15;
psDec->sCNG.CNG_smth_NLSF_Q15[ i ] = NLSF_acc_Q15;
}
psDec->sCNG.CNG_smth_Gain_Q16 = 0;
psDec->sCNG.rand_seed = 3176576;
}
/* Updates CNG estimate, and applies the CNG when packet was lost */
void SKP_Silk_CNG(
SKP_Silk_decoder_state *psDec, /* I/O Decoder state */
SKP_Silk_decoder_control *psDecCtrl, /* I/O Decoder control */
SKP_int16 signal[], /* I/O Signal */
SKP_int length /* I Length of residual */
)
{
SKP_int i, subfr;
SKP_int32 tmp_32, Gain_Q26, max_Gain_Q16;
SKP_int16 LPC_buf[ MAX_LPC_ORDER ];
SKP_int16 CNG_sig[ MAX_FRAME_LENGTH ];
SKP_Silk_CNG_struct *psCNG;
psCNG = &psDec->sCNG;
if( psDec->fs_kHz != psCNG->fs_kHz ) {
/* Reset state */
SKP_Silk_CNG_Reset( psDec );
psCNG->fs_kHz = psDec->fs_kHz;
}
if( psDec->lossCnt == 0 && psDec->prevSignalType == TYPE_NO_VOICE_ACTIVITY ) {
/* Update CNG parameters */
/* Smoothing of LSF's */
for( i = 0; i < psDec->LPC_order; i++ ) {
psCNG->CNG_smth_NLSF_Q15[ i ] += SKP_SMULWB( psDec->prevNLSF_Q15[ i ] - psCNG->CNG_smth_NLSF_Q15[ i ], CNG_NLSF_SMTH_Q16 );
}
/* Find the subframe with the highest gain */
max_Gain_Q16 = 0;
subfr = 0;
for( i = 0; i < psDec->nb_subfr; i++ ) {
if( psDecCtrl->Gains_Q16[ i ] > max_Gain_Q16 ) {
max_Gain_Q16 = psDecCtrl->Gains_Q16[ i ];
subfr = i;
}
}
/* Update CNG excitation buffer with excitation from this subframe */
SKP_memmove( &psCNG->CNG_exc_buf_Q10[ psDec->subfr_length ], psCNG->CNG_exc_buf_Q10, ( psDec->nb_subfr - 1 ) * psDec->subfr_length * sizeof( SKP_int32 ) );
SKP_memcpy( psCNG->CNG_exc_buf_Q10, &psDec->exc_Q10[ subfr * psDec->subfr_length ], psDec->subfr_length * sizeof( SKP_int32 ) );
/* Smooth gains */
for( i = 0; i < psDec->nb_subfr; i++ ) {
psCNG->CNG_smth_Gain_Q16 += SKP_SMULWB( psDecCtrl->Gains_Q16[ i ] - psCNG->CNG_smth_Gain_Q16, CNG_GAIN_SMTH_Q16 );
}
}
/* Add CNG when packet is lost and / or when low speech activity */
if( psDec->lossCnt ) {
/* Generate CNG excitation */
SKP_Silk_CNG_exc( CNG_sig, psCNG->CNG_exc_buf_Q10,
psCNG->CNG_smth_Gain_Q16, length, &psCNG->rand_seed );
/* Convert CNG NLSF to filter representation */
SKP_Silk_NLSF2A_stable( LPC_buf, psCNG->CNG_smth_NLSF_Q15, psDec->LPC_order );
Gain_Q26 = ( SKP_int32 )1 << 26; /* 1.0 */
/* Generate CNG signal, by synthesis filtering */
if( psDec->LPC_order == 16 ) {
SKP_Silk_LPC_synthesis_order16( CNG_sig, LPC_buf,
Gain_Q26, psCNG->CNG_synth_state, CNG_sig, length );
} else {
SKP_Silk_LPC_synthesis_filter( CNG_sig, LPC_buf,
Gain_Q26, psCNG->CNG_synth_state, CNG_sig, length, psDec->LPC_order );
}
/* Mix with signal */
for( i = 0; i < length; i++ ) {
tmp_32 = signal[ i ] + CNG_sig[ i ];
signal[ i ] = SKP_SAT16( tmp_32 );
}
} else {
SKP_memset( psCNG->CNG_synth_state, 0, psDec->LPC_order * sizeof( SKP_int32 ) );
}
}