SKP_int SKP_Silk_init_decoder(
SKP_Silk_decoder_state *psDec /* I/O Decoder state pointer */
)
{
SKP_memset( psDec, 0, sizeof( SKP_Silk_decoder_state ) );
/* Set sampling rate to 24 kHz, and init non-zero values */
SKP_Silk_decoder_set_fs( psDec, 24 );
/* Used to deactivate e.g. LSF interpolation and fluctuation reduction */
psDec->first_frame_after_reset = 1;
psDec->prev_inv_gain_Q16 = 65536;
/* Reset CNG state */
SKP_Silk_CNG_Reset( psDec );
SKP_Silk_PLC_Reset( psDec );
return(0);
}
/* 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->vadFlag == 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 < 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, ( 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 < 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 ) {//|| psDec->vadFlag == NO_VOICE_ACTIVITY ) {
/* 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 ) );
}
}
