opus/silk/decoder_set_fs.c

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#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "main.h"

static const int dec_delay_matrix[3][5] = {
/*SILK API 8  12  16  24  48 */
/* 8 */   {3, 0, 2, 0, 0},
/*12 */   {0, 8, 5, 7, 5},
/*16 */   {0, 0, 8, 5, 5}
};

/* Set decoder sampling rate */
opus_int silk_decoder_set_fs(
    silk_decoder_state          *psDec,                         /* I/O  Decoder state pointer                       */
    opus_int                    fs_kHz,                         /* I    Sampling frequency (kHz)                    */
    opus_int                    fs_API_Hz                       /* I    API Sampling frequency (Hz)                 */
)
{
    opus_int frame_length, ret = 0;

    silk_assert( fs_kHz == 8 || fs_kHz == 12 || fs_kHz == 16 );
    silk_assert( psDec->nb_subfr == MAX_NB_SUBFR || psDec->nb_subfr == MAX_NB_SUBFR/2 );

    /* New (sub)frame length */
    psDec->subfr_length = silk_SMULBB( SUB_FRAME_LENGTH_MS, fs_kHz );
    frame_length = silk_SMULBB( psDec->nb_subfr, psDec->subfr_length );

    /* Initialize resampler when switching internal or external sampling frequency */
    if( psDec->fs_kHz != fs_kHz || psDec->fs_API_hz != fs_API_Hz ) {
        /* Allocate worst case space for temporary upsampling, 8 to 48 kHz, so a factor 6 */
        opus_int16 temp_buf[ MAX_FRAME_LENGTH_MS * MAX_API_FS_KHZ ];
        silk_resampler_state_struct  temp_resampler_state;

        /* New delay value */
        psDec->delay = dec_delay_matrix[ rateID( silk_SMULBB( fs_kHz, 1000 ) ) ][ rateID( fs_API_Hz ) ];
        silk_assert( psDec->delay <= MAX_DECODER_DELAY );

        if( psDec->fs_kHz != fs_kHz && psDec->fs_kHz > 0 ) {
            /* Initialize resampler for temporary resampling of outBuf data to the new internal sampling rate */
            ret += silk_resampler_init( &temp_resampler_state, silk_SMULBB( psDec->fs_kHz, 1000 ), silk_SMULBB( fs_kHz, 1000 ) );

            /* Temporary resampling of outBuf data to the new internal sampling rate */
            silk_memcpy( temp_buf, psDec->outBuf, psDec->frame_length * sizeof( opus_int16 ) );
            ret += silk_resampler( &temp_resampler_state, psDec->outBuf, temp_buf, psDec->frame_length );
        }

        /* Initialize the resampler for dec_API.c preparing resampling from fs_kHz to API_fs_Hz */
        ret += silk_resampler_init( &psDec->resampler_state, silk_SMULBB( fs_kHz, 1000 ), fs_API_Hz );

        /* Correct resampler state by resampling buffered data from fs_kHz to API_fs_Hz */
        ret += silk_resampler( &psDec->resampler_state, temp_buf, psDec->outBuf, frame_length );

        psDec->fs_API_hz = fs_API_Hz;
    }

    if( psDec->fs_kHz != fs_kHz || frame_length != psDec->frame_length ) {
        if( fs_kHz == 8 ) {
            if( psDec->nb_subfr == MAX_NB_SUBFR ) {
                psDec->pitch_contour_iCDF = silk_pitch_contour_NB_iCDF;
            } else {
                psDec->pitch_contour_iCDF = silk_pitch_contour_10_ms_NB_iCDF;
            }
        } else {
            if( psDec->nb_subfr == MAX_NB_SUBFR ) {
                psDec->pitch_contour_iCDF = silk_pitch_contour_iCDF;
            } else {
                psDec->pitch_contour_iCDF = silk_pitch_contour_10_ms_iCDF;
            }
        }
        if( psDec->fs_kHz != fs_kHz ) {
            psDec->ltp_mem_length = silk_SMULBB( LTP_MEM_LENGTH_MS, fs_kHz );
            if( fs_kHz == 8 || fs_kHz == 12 ) {
                psDec->LPC_order = MIN_LPC_ORDER;
                psDec->psNLSF_CB = &silk_NLSF_CB_NB_MB;
            } else {
                psDec->LPC_order = MAX_LPC_ORDER;
                psDec->psNLSF_CB = &silk_NLSF_CB_WB;
            }
            if( fs_kHz == 16 ) {
                psDec->pitch_lag_low_bits_iCDF = silk_uniform8_iCDF;
            } else if( fs_kHz == 12 ) {
                psDec->pitch_lag_low_bits_iCDF = silk_uniform6_iCDF;
            } else if( fs_kHz == 8 ) {
                psDec->pitch_lag_low_bits_iCDF = silk_uniform4_iCDF;
            } else {
                /* unsupported sampling rate */
                silk_assert( 0 );
            }
            psDec->first_frame_after_reset = 1;
            psDec->lagPrev                 = 100;
            psDec->LastGainIndex           = 10;
            psDec->prevSignalType          = TYPE_NO_VOICE_ACTIVITY;
        }

        psDec->fs_kHz       = fs_kHz;
        psDec->frame_length = frame_length;
    }

    /* Check that settings are valid */
    silk_assert( psDec->frame_length > 0 && psDec->frame_length <= MAX_FRAME_LENGTH );

    return ret;
}